diff options
35 files changed, 784 insertions, 1355 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 1144ea3229a3..e9c18dabc552 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -994,6 +994,9 @@ This is a directory, with the following entries: * ``boot_id``: a UUID generated the first time this is retrieved, and unvarying after that; +* ``uuid``: a UUID generated every time this is retrieved (this can + thus be used to generate UUIDs at will); + * ``entropy_avail``: the pool's entropy count, in bits; * ``poolsize``: the entropy pool size, in bits; @@ -1001,10 +1004,7 @@ This is a directory, with the following entries: * ``urandom_min_reseed_secs``: obsolete (used to determine the minimum number of seconds between urandom pool reseeding). This file is writable for compatibility purposes, but writing to it has no effect - on any RNG behavior. - -* ``uuid``: a UUID generated every time this is retrieved (this can - thus be used to generate UUIDs at will); + on any RNG behavior; * ``write_wakeup_threshold``: when the entropy count drops below this (as a number of bits), processes waiting to write to ``/dev/random`` diff --git a/arch/alpha/include/asm/timex.h b/arch/alpha/include/asm/timex.h index b565cc6f408e..f89798da8a14 100644 --- a/arch/alpha/include/asm/timex.h +++ b/arch/alpha/include/asm/timex.h @@ -28,5 +28,6 @@ static inline cycles_t get_cycles (void) __asm__ __volatile__ ("rpcc %0" : "=r"(ret)); return ret; } +#define get_cycles get_cycles #endif diff --git a/arch/arm/include/asm/timex.h b/arch/arm/include/asm/timex.h index 7c3b3671d6c2..6d1337c169cd 100644 --- a/arch/arm/include/asm/timex.h +++ b/arch/arm/include/asm/timex.h @@ -11,5 +11,6 @@ typedef unsigned long cycles_t; #define get_cycles() ({ cycles_t c; read_current_timer(&c) ? 0 : c; }) +#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback()) #endif diff --git a/arch/ia64/include/asm/timex.h b/arch/ia64/include/asm/timex.h index 869a3ac6bf23..7ccc077a60be 100644 --- a/arch/ia64/include/asm/timex.h +++ b/arch/ia64/include/asm/timex.h @@ -39,6 +39,7 @@ get_cycles (void) ret = ia64_getreg(_IA64_REG_AR_ITC); return ret; } +#define get_cycles get_cycles extern void ia64_cpu_local_tick (void); extern unsigned long long ia64_native_sched_clock (void); diff --git a/arch/m68k/include/asm/timex.h b/arch/m68k/include/asm/timex.h index 6a21d9358280..f4a7a340f4ca 100644 --- a/arch/m68k/include/asm/timex.h +++ b/arch/m68k/include/asm/timex.h @@ -35,7 +35,7 @@ static inline unsigned long random_get_entropy(void) { if (mach_random_get_entropy) return mach_random_get_entropy(); - return 0; + return random_get_entropy_fallback(); } #define random_get_entropy random_get_entropy diff --git a/arch/mips/include/asm/timex.h b/arch/mips/include/asm/timex.h index 8026baf46e72..2e107886f97a 100644 --- a/arch/mips/include/asm/timex.h +++ b/arch/mips/include/asm/timex.h @@ -76,25 +76,24 @@ static inline cycles_t get_cycles(void) else return 0; /* no usable counter */ } +#define get_cycles get_cycles /* * Like get_cycles - but where c0_count is not available we desperately * use c0_random in an attempt to get at least a little bit of entropy. - * - * R6000 and R6000A neither have a count register nor a random register. - * That leaves no entropy source in the CPU itself. */ static inline unsigned long random_get_entropy(void) { - unsigned int prid = read_c0_prid(); - unsigned int imp = prid & PRID_IMP_MASK; + unsigned int c0_random; - if (can_use_mips_counter(prid)) + if (can_use_mips_counter(read_c0_prid())) return read_c0_count(); - else if (likely(imp != PRID_IMP_R6000 && imp != PRID_IMP_R6000A)) - return read_c0_random(); + + if (cpu_has_3kex) + c0_random = (read_c0_random() >> 8) & 0x3f; else - return 0; /* no usable register */ + c0_random = read_c0_random() & 0x3f; + return (random_get_entropy_fallback() << 6) | (0x3f - c0_random); } #define random_get_entropy random_get_entropy diff --git a/arch/nios2/include/asm/timex.h b/arch/nios2/include/asm/timex.h index a769f871b28d..40a1adc9bd03 100644 --- a/arch/nios2/include/asm/timex.h +++ b/arch/nios2/include/asm/timex.h @@ -8,5 +8,8 @@ typedef unsigned long cycles_t; extern cycles_t get_cycles(void); +#define get_cycles get_cycles + +#define random_get_entropy() (((unsigned long)get_cycles()) ?: random_get_entropy_fallback()) #endif diff --git a/arch/openrisc/include/asm/timex.h b/arch/openrisc/include/asm/timex.h index d52b4e536e3f..5487fa93dd9b 100644 --- a/arch/openrisc/include/asm/timex.h +++ b/arch/openrisc/include/asm/timex.h @@ -23,6 +23,7 @@ static inline cycles_t get_cycles(void) { return mfspr(SPR_TTCR); } +#define get_cycles get_cycles /* This isn't really used any more */ #define CLOCK_TICK_RATE 1000 diff --git a/arch/openrisc/kernel/head.S b/arch/openrisc/kernel/head.S index 15f1b38dfe03..2fa6cefa62ca 100644 --- a/arch/openrisc/kernel/head.S +++ b/arch/openrisc/kernel/head.S @@ -521,6 +521,15 @@ _start: l.ori r3,r0,0x1 l.mtspr r0,r3,SPR_SR + /* + * Start the TTCR as early as possible, so that the RNG can make use of + * measurements of boot time from the earliest opportunity. Especially + * important is that the TTCR does not return zero by the time we reach + * random_init(). + */ + l.movhi r3,hi(SPR_TTMR_CR) + l.mtspr r0,r3,SPR_TTMR + CLEAR_GPR(r1) CLEAR_GPR(r2) CLEAR_GPR(r3) diff --git a/arch/parisc/include/asm/timex.h b/arch/parisc/include/asm/timex.h index 06b510f8172e..b4622cb06a75 100644 --- a/arch/parisc/include/asm/timex.h +++ b/arch/parisc/include/asm/timex.h @@ -13,9 +13,10 @@ typedef unsigned long cycles_t; -static inline cycles_t get_cycles (void) +static inline cycles_t get_cycles(void) { return mfctl(16); } +#define get_cycles get_cycles #endif diff --git a/arch/powerpc/include/asm/timex.h b/arch/powerpc/include/asm/timex.h index fa2e76e4093a..14b4489de52c 100644 --- a/arch/powerpc/include/asm/timex.h +++ b/arch/powerpc/include/asm/timex.h @@ -19,6 +19,7 @@ static inline cycles_t get_cycles(void) { return mftb(); } +#define get_cycles get_cycles #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_TIMEX_H */ diff --git a/arch/riscv/include/asm/timex.h b/arch/riscv/include/asm/timex.h index 507cae273bc6..d6a7428f6248 100644 --- a/arch/riscv/include/asm/timex.h +++ b/arch/riscv/include/asm/timex.h @@ -41,7 +41,7 @@ static inline u32 get_cycles_hi(void) static inline unsigned long random_get_entropy(void) { if (unlikely(clint_time_val == NULL)) - return 0; + return random_get_entropy_fallback(); return get_cycles(); } #define random_get_entropy() random_get_entropy() diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h index 2cfce42aa7fc..ce878e85b6e4 100644 --- a/arch/s390/include/asm/timex.h +++ b/arch/s390/include/asm/timex.h @@ -197,6 +197,7 @@ static inline cycles_t get_cycles(void) { return (cycles_t) get_tod_clock() >> 2; } +#define get_cycles get_cycles int get_phys_clock(unsigned long *clock); void init_cpu_timer(void); diff --git a/arch/sparc/include/asm/timex_32.h b/arch/sparc/include/asm/timex_32.h index 542915b46209..f86326a6f89e 100644 --- a/arch/sparc/include/asm/timex_32.h +++ b/arch/sparc/include/asm/timex_32.h @@ -9,8 +9,6 @@ #define CLOCK_TICK_RATE 1193180 /* Underlying HZ */ -/* XXX Maybe do something better at some point... -DaveM */ -typedef unsigned long cycles_t; -#define get_cycles() (0) +#include <asm-generic/timex.h> #endif diff --git a/arch/um/include/asm/timex.h b/arch/um/include/asm/timex.h index e392a9a5bc9b..9f27176adb26 100644 --- a/arch/um/include/asm/timex.h +++ b/arch/um/include/asm/timex.h @@ -2,13 +2,8 @@ #ifndef __UM_TIMEX_H #define __UM_TIMEX_H -typedef unsigned long cycles_t; - -static inline cycles_t get_cycles (void) -{ - return 0; -} - #define CLOCK_TICK_RATE (HZ) +#include <asm-generic/timex.h> + #endif diff --git a/arch/x86/include/asm/timex.h b/arch/x86/include/asm/timex.h index a4a8b1b16c0c..956e4145311b 100644 --- a/arch/x86/include/asm/timex.h +++ b/arch/x86/include/asm/timex.h @@ -5,6 +5,15 @@ #include <asm/processor.h> #include <asm/tsc.h> +static inline unsigned long random_get_entropy(void) +{ + if (!IS_ENABLED(CONFIG_X86_TSC) && + !cpu_feature_enabled(X86_FEATURE_TSC)) + return random_get_entropy_fallback(); + return rdtsc(); +} +#define random_get_entropy random_get_entropy + /* Assume we use the PIT time source for the clock tick */ #define CLOCK_TICK_RATE PIT_TICK_RATE diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h index 01a300a9700b..fbdc3d951494 100644 --- a/arch/x86/include/asm/tsc.h +++ b/arch/x86/include/asm/tsc.h @@ -20,13 +20,12 @@ extern void disable_TSC(void); static inline cycles_t get_cycles(void) { -#ifndef CONFIG_X86_TSC - if (!boot_cpu_has(X86_FEATURE_TSC)) + if (!IS_ENABLED(CONFIG_X86_TSC) && + !cpu_feature_enabled(X86_FEATURE_TSC)) return 0; -#endif - return rdtsc(); } +#define get_cycles get_cycles extern struct system_counterval_t convert_art_to_tsc(u64 art); extern struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns); diff --git a/arch/xtensa/include/asm/timex.h b/arch/xtensa/include/asm/timex.h index 233ec75e60c6..3f2462f2d027 100644 --- a/arch/xtensa/include/asm/timex.h +++ b/arch/xtensa/include/asm/timex.h @@ -29,10 +29,6 @@ extern unsigned long ccount_freq; -typedef unsigned long long cycles_t; - -#define get_cycles() (0) - void local_timer_setup(unsigned cpu); /* @@ -59,4 +55,6 @@ static inline void set_linux_timer (unsigned long ccompare) xtensa_set_sr(ccompare, SREG_CCOMPARE + LINUX_TIMER); } +#include <asm-generic/timex.h> + #endif /* _XTENSA_TIMEX_H */ diff --git a/drivers/char/random.c b/drivers/char/random.c index 4c9adb4f3d5d..b691b9d59503 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -15,14 +15,12 @@ * - Sysctl interface. * * The high level overview is that there is one input pool, into which - * various pieces of data are hashed. Some of that data is then "credited" as - * having a certain number of bits of entropy. When enough bits of entropy are - * available, the hash is finalized and handed as a key to a stream cipher that - * expands it indefinitely for various consumers. This key is periodically - * refreshed as the various entropy collectors, described below, add data to the - * input pool and credit it. There is currently no Fortuna-like scheduler - * involved, which can lead to malicious entropy sources causing a premature - * reseed, and the entropy estimates are, at best, conservative guesses. + * various pieces of data are hashed. Prior to initialization, some of that + * data is then "credited" as having a certain number of bits of entropy. + * When enough bits of entropy are available, the hash is finalized and + * handed as a key to a stream cipher that expands it indefinitely for + * various consumers. This key is periodically refreshed as the various + * entropy collectors, described below, add data to the input pool. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt @@ -53,6 +51,8 @@ #include <linux/completion.h> #include <linux/uuid.h> #include <linux/uaccess.h> +#include <linux/suspend.h> +#include <linux/siphash.h> #include <crypto/chacha.h> #include <crypto/blake2s.h> #include <asm/processor.h> @@ -71,27 +71,25 @@ *********************************************************************/ /* - * crng_init = 0 --> Uninitialized - * 1 --> Initialized - * 2 --> Initialized from input_pool - * * crng_init is protected by base_crng->lock, and only increases - * its value (from 0->1->2). + * its value (from empty->early->ready). */ -static int crng_init = 0; -#define crng_ready() (likely(crng_init > 1)) -/* Various types of waiters for crng_init->2 transition. */ +static enum { + CRNG_EMPTY = 0, /* Little to no entropy collected */ + CRNG_EARLY = 1, /* At least POOL_EARLY_BITS collected */ + CRNG_READY = 2 /* Fully initialized with POOL_READY_BITS collected */ +} crng_init __read_mostly = CRNG_EMPTY; +static DEFINE_STATIC_KEY_FALSE(crng_is_ready); +#define crng_ready() (static_branch_likely(&crng_is_ready) || crng_init >= CRNG_READY) +/* Various types of waiters for crng_init->CRNG_READY transition. */ static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); static struct fasync_struct *fasync; -static DEFINE_SPINLOCK(random_ready_chain_lock); -static RAW_NOTIFIER_HEAD(random_ready_chain); /* Control how we warn userspace. */ -static struct ratelimit_state unseeded_warning = - RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3); static struct ratelimit_state urandom_warning = RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3); -static int ratelimit_disable __read_mostly; +static int ratelimit_disable __read_mostly = + IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM); module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); @@ -110,6 +108,11 @@ bool rng_is_initialized(void) } EXPORT_SYMBOL(rng_is_initialized); +static void __cold crng_set_ready(struct work_struct *work) +{ + static_branch_enable(&crng_is_ready); +} + /* Used by wait_for_random_bytes(), and considered an entropy collector, below. */ static void try_to_generate_entropy(void); @@ -137,73 +140,10 @@ int wait_for_random_bytes(void) } EXPORT_SYMBOL(wait_for_random_bytes); -/* - * Add a callback function that will be invoked when the input - * pool is initialised. - * - * returns: 0 if callback is successfully added - * -EALREADY if pool is already initialised (callback not called) - */ -int register_random_ready_notifier(struct notifier_block *nb) -{ - unsigned long flags; - int ret = -EALREADY; - - if (crng_ready()) - return ret; - - spin_lock_irqsave(&random_ready_chain_lock, flags); - if (!crng_ready()) - ret = raw_notifier_chain_register(&random_ready_chain, nb); - spin_unlock_irqrestore(&random_ready_chain_lock, flags); - return ret; -} - -/* - * Delete a previously registered readiness callback function. - */ -int unregister_random_ready_notifier(struct notifier_block *nb) -{ - unsigned long flags; - int ret; - - spin_lock_irqsave(&random_ready_chain_lock, flags); - ret = raw_notifier_chain_unregister(&random_ready_chain, nb); - spin_unlock_irqrestore(&random_ready_chain_lock, flags); - return ret; -} - -static void process_random_ready_list(void) -{ - unsigned long flags; - - spin_lock_irqsave(&random_ready_chain_lock, flags); - raw_notifier_call_chain(&random_ready_chain, 0, NULL); - spin_unlock_irqrestore(&random_ready_chain_lock, flags); -} - -#define warn_unseeded_randomness(previous) \ - _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous)) - -static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous) -{ -#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM - const bool print_once = false; -#else - static bool print_once __read_mostly; -#endif - - if (print_once || crng_ready() || - (previous && (caller == READ_ONCE(*previous)))) - return; - WRITE_ONCE(*previous, caller); -#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM - print_once = true; -#endif - if (__ratelimit(&unseeded_warning)) - printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", - func_name, caller, crng_init); -} +#define warn_unseeded_randomness() \ + if (IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM) && !crng_ready()) \ + printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", \ + __func__, (void *)_RET_IP_, crng_init) /********************************************************************* @@ -216,7 +156,7 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller, void * * There are a few exported interfaces for use by other drivers: * - * void get_random_bytes(void *buf, size_t nbytes) + * void get_random_bytes(void *buf, size_t len) * u32 get_random_u32() * u64 get_random_u64() * unsigned int get_random_int() @@ -232,8 +172,8 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller, void *********************************************************************/ enum { - CRNG_RESEED_INTERVAL = 300 * HZ, - CRNG_INIT_CNT_THRESH = 2 * CHACHA_KEY_SIZE + CRNG_RESEED_START_INTERVAL = HZ, + CRNG_RESEED_INTERVAL = 60 * HZ }; static struct { @@ -256,24 +196,17 @@ static DEFINE_PER_CPU(struct crng, crngs) = { .lock = INIT_LOCAL_LOCK(crngs.lock), }; -/* Used by crng_reseed() to extract a new seed from the input pool. */ -static bool drain_entropy(void *buf, size_t nbytes, bool force); +/* Used by crng_reseed() and crng_make_state() to extract a new seed from the input pool. */ +static void extract_entropy(void *buf, size_t len); -/* - * This extracts a new crng key from the input pool, but only if there is a - * sufficient amount of entropy available or force is true, in order to - * mitigate bruteforcing of newly added bits. - */ -static void crng_reseed(bool force) +/* This extracts a new crng key from the input pool. */ +static void crng_reseed(void) { unsigned long flags; unsigned long next_gen; u8 key[CHACHA_KEY_SIZE]; - bool finalize_init = false; - /* Only reseed if we can, to prevent brute forcing a small amount of new bits. */ - if (!drain_entropy(key, sizeof(key), force)) - return; + extract_entropy(key, sizeof(key)); /* * We copy the new key into the base_crng, overwriting the old one, @@ -288,28 +221,10 @@ static void crng_reseed(bool force) ++next_gen; WRITE_ONCE(base_crng.generation, next_gen); WRITE_ONCE(base_crng.birth, jiffies); - if (!crng_ready()) { - crng_init = 2; - finalize_init = true; - } + if (!static_branch_likely(&crng_is_ready)) + crng_init = CRNG_READY; spin_unlock_irqrestore(&base_crng.lock, flags); memzero_explicit(key, sizeof(key)); - if (finalize_init) { - process_random_ready_list(); - wake_up_interruptible(&crng_init_wait); - kill_fasync(&fasync, SIGIO, POLL_IN); - pr_notice("crng init done\n"); - if (unseeded_warning.missed) { - pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n", - unseeded_warning.missed); - unseeded_warning.missed = 0; - } - if (urandom_warning.missed) { - pr_notice("%d urandom warning(s) missed due to ratelimiting\n", - urandom_warning.missed); - urandom_warning.missed = 0; - } - } } /* @@ -345,10 +260,10 @@ static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE], } /* - * Return whether the crng seed is considered to be sufficiently - * old that a reseeding might be attempted. This happens if the last - * reseeding was CRNG_RESEED_INTERVAL ago, or during early boot, at - * an interval proportional to the uptime. + * Return whether the crng seed is considered to be sufficiently old + * that a reseeding is needed. This happens if the last reseeding + * was CRNG_RESEED_INTERVAL ago, or during early boot, at an interval + * proportional to the uptime. */ static bool crng_has_old_seed(void) { @@ -360,10 +275,10 @@ static bool crng_has_old_seed(void) if (uptime >= CRNG_RESEED_INTERVAL / HZ * 2) WRITE_ONCE(early_boot, false); else - interval = max_t(unsigned int, 5 * HZ, + interval = max_t(unsigned int, CRNG_RESEED_START_INTERVAL, (unsigned int)uptime / 2 * HZ); } - return time_after(jiffies, READ_ONCE(base_crng.birth) + interval); + return time_is_before_jiffies(READ_ONCE(base_crng.birth) + interval); } /* @@ -382,28 +297,31 @@ static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS], /* * For the fast path, we check whether we're ready, unlocked first, and * then re-check once locked later. In the case where we're really not - * ready, we do fast key erasure with the base_crng directly, because - * this is what crng_pre_init_inject() mutates during early init. + * ready, we do fast key erasure with the base_crng directly, extracting + * when crng_init is CRNG_EMPTY. */ if (!crng_ready()) { bool ready; spin_lock_irqsave(&base_crng.lock, flags); ready = crng_ready(); - if (!ready) + if (!ready) { + if (crng_init == CRNG_EMPTY) + extract_entropy(base_crng.key, sizeof(base_crng.key)); crng_fast_key_erasure(base_crng.key, chacha_state, random_data, random_data_len); + } spin_unlock_irqrestore(&base_crng.lock, flags); if (!ready) return; } /* - * If the base_crng is old enough, we try to reseed, which in turn - * bumps the generation counter that we check below. + * If the base_crng is old enough, we reseed, which in turn bumps the + * generation counter that we check below. */ if (unlikely(crng_has_old_seed())) - crng_reseed(false); + crng_reseed(); local_lock_irqsave(&crngs.lock, flags); crng = raw_cpu_ptr(&crngs); @@ -433,68 +351,24 @@ static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS], local_unlock_irqrestore(&crngs.lock, flags); } -/* - * This function is for crng_init == 0 only. It loads entropy directly - * into the crng's key, without going through the input pool. It is, - * generally speaking, not very safe, but we use this only at early - * boot time when it's better to have something there rather than - * nothing. - * - * If account is set, then the crng_init_cnt counter is incremented. - * This shouldn't be set by functions like add_device_randomness(), - * where we can't trust the buffer passed to it is guaranteed to be - * unpredictable (so it might not have any entropy at all). - */ -static void crng_pre_init_inject(const void *input, size_t len, bool account) -{ - static int crng_init_cnt = 0; - struct blake2s_state hash; - unsigned long flags; - - blake2s_init(&hash, sizeof(base_crng.key)); - - spin_lock_irqsave(&base_crng.lock, flags); - if (crng_init != 0) { - spin_unlock_irqrestore(&base_crng.lock, flags); - return; - } - - blake2s_update(&hash, base_crng.key, sizeof(base_crng.key)); - blake2s_update(&hash, input, len); - blake2s_final(&hash, base_crng.key); - - if (account) { - crng_init_cnt += min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt); - if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) { - ++base_crng.generation; - crng_init = 1; - } - } - - spin_unlock_irqrestore(&base_crng.lock, flags); - - if (crng_init == 1) - pr_notice("fast init done\n"); -} - -static void _get_random_bytes(void *buf, size_t nbytes) +static void _get_random_bytes(void *buf, size_t len) { u32 chacha_state[CHACHA_STATE_WORDS]; u8 tmp[CHACHA_BLOCK_SIZE]; - size_t len; + size_t first_block_len; - if (!nbytes) + if (!len) return; - len = min_t(size_t, 32, nbytes); - crng_make_state(chacha_state, buf, len); - nbytes -= len; - buf += len; + first_block_len = min_t(size_t, 32, len); + crng_make_state(chacha_state, buf, first_block_len); + len -= first_block_len; + buf += first_block_len; - while (nbytes) { - if (nbytes < CHACHA_BLOCK_SIZE) { + while (len) { + if (len < CHACHA_BLOCK_SIZE) { chacha20_block(chacha_state, tmp); - memcpy(buf, tmp, nbytes); + memcpy(buf, tmp, len); memzero_explicit(tmp, sizeof(tmp)); break; } @@ -502,7 +376,7 @@ static void _get_random_bytes(void *buf, size_t nbytes) chacha20_block(chacha_state, buf); if (unlikely(chacha_state[12] == 0)) ++chacha_state[13]; - nbytes -= CHACHA_BLOCK_SIZE; + len -= CHACHA_BLOCK_SIZE; buf += CHACHA_BLOCK_SIZE; } @@ -512,29 +386,24 @@ static void _get_random_bytes(void *buf, size_t nbytes) /* * This function is the exported kernel interface. It returns some * number of good random numbers, suitable for key generation, seeding - * TCP sequence numbers, etc. It does not rely on the hardware random - * number generator. For random bytes direct from the hardware RNG - * (when available), use get_random_bytes_arch(). In order to ensure - * that the randomness provided by this function is okay, the function - * wait_for_random_bytes() should be called and return 0 at least once - * at any point prior. + * TCP sequence numbers, etc. In order to ensure that the randomness + * by this function is okay, the function wait_for_random_bytes() + * should be called and return 0 at least once at any point prior. */ -void get_random_bytes(void *buf, size_t nbytes) +void get_random_bytes(void *buf, size_t len) { - static void *previous; - - warn_unseeded_randomness(&previous); - _get_random_bytes(buf, nbytes); + warn_unseeded_randomness(); + _get_random_bytes(buf, len); } EXPORT_SYMBOL(get_random_bytes); -static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes) +static ssize_t get_random_bytes_user(struct iov_iter *iter) { - size_t len, left, ret = 0; u32 chacha_state[CHACHA_STATE_WORDS]; - u8 output[CHACHA_BLOCK_SIZE]; + u8 block[CHACHA_BLOCK_SIZE]; + size_t ret = 0, copied; - if (!nbytes) + if (unlikely(!iov_iter_count(iter))) return 0; /* @@ -548,30 +417,22 @@ static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes) * use chacha_state after, so we can simply return those bytes to * the user directly. */ - if (nbytes <= CHACHA_KEY_SIZE) { - ret = nbytes - copy_to_user(buf, &chacha_state[4], nbytes); + if (iov_iter_count(iter) <= CHACHA_KEY_SIZE) { + ret = copy_to_iter(&chacha_state[4], CHACHA_KEY_SIZE, iter); goto out_zero_chacha; } for (;;) { - chacha20_block(chacha_state, output); + chacha20_block(chacha_state, block); if (unlikely(chacha_state[12] == 0)) ++chacha_state[13]; - len = min_t(size_t, nbytes, CHACHA_BLOCK_SIZE); - left = copy_to_user(buf, output, len); - if (left) { - ret += len - left; - break; - } - - buf += len; - ret += len; - nbytes -= len; - if (!nbytes) + copied = copy_to_iter(block, sizeof(block), iter); + ret += copied; + if (!iov_iter_count(iter) || copied != sizeof(block)) break; - BUILD_BUG_ON(PAGE_SIZE % CHACHA_BLOCK_SIZE != 0); + BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0); if (ret % PAGE_SIZE == 0) { if (signal_pending(current)) break; @@ -579,7 +440,7 @@ static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes) } } - memzero_explicit(output, sizeof(output)); + memzero_explicit(block, sizeof(block)); out_zero_chacha: memzero_explicit(chacha_state, sizeof(chacha_state)); return ret ? ret : -EFAULT; @@ -591,98 +452,69 @@ out_zero_chacha: * provided by this function is okay, the function wait_for_random_bytes() * should be called and return 0 at least once at any point prior. */ -struct batched_entropy { - union { - /* - * We make this 1.5x a ChaCha block, so that we get the - * remaining 32 bytes from fast key erasure, plus one full - * block from the detached ChaCha state. We can increase - * the size of this later if needed so long as we keep the - * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE. - */ - u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))]; - u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))]; - }; - local_lock_t lock; - unsigned long generation; - unsigned int position; -}; - -static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = { - .lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock), - .position = UINT_MAX -}; - -u64 get_random_u64(void) -{ - u64 ret; - unsigned long flags; - struct batched_entropy *batch; - static void *previous; - unsigned long next_gen; - - warn_unseeded_randomness(&previous); - - local_lock_irqsave(&batched_entropy_u64.lock, flags); - batch = raw_cpu_ptr(&batched_entropy_u64); - - next_gen = READ_ONCE(base_crng.generation); - if (batch->position >= ARRAY_SIZE(batch->entropy_u64) || - next_gen != batch->generation) { - _get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64)); - batch->position = 0; - batch->generation = next_gen; - } - - ret = batch->entropy_u64[batch->position]; - batch->entropy_u64[batch->position] = 0; - ++batch->position; - local_unlock_irqrestore(&batched_entropy_u64.lock, flags); - return ret; -} -EXPORT_SYMBOL(get_random_u64); - -static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = { - .lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock), - .position = UINT_MAX -}; - -u32 get_random_u32(void) -{ - u32 ret; - unsigned long flags; - struct batched_entropy *batch; - static void *previous; - unsigned long next_gen; - - warn_unseeded_randomness(&previous); - - local_lock_irqsave(&batched_entropy_u32.lock, flags); - batch = raw_cpu_ptr(&batched_entropy_u32); - - next_gen = READ_ONCE(base_crng.generation); - if (batch->position >= ARRAY_SIZE(batch->entropy_u32) || - next_gen != batch->generation) { - _get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32)); - batch->position = 0; - batch->generation = next_gen; - } - - ret = batch->entropy_u32[batch->position]; - batch->entropy_u32[batch->position] = 0; - ++batch->position; - local_unlock_irqrestore(&batched_entropy_u32.lock, flags); - return ret; -} -EXPORT_SYMBOL(get_random_u32); +#define DEFINE_BATCHED_ENTROPY(type) \ +struct batch_ ##type { \ + /* \ + * We make this 1.5x a ChaCha block, so that we get the \ + * remaining 32 bytes from fast key erasure, plus one full \ + * block from the detached ChaCha state. We can increase \ + * the size of this later if needed so long as we keep the \ + * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE. \ + */ \ + type entropy[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(type))]; \ + local_lock_t lock; \ + unsigned long generation; \ + unsigned int position; \ +}; \ + \ +static DEFINE_PER_CPU(struct batch_ ##type, batched_entropy_ ##type) = { \ + .lock = INIT_LOCAL_LOCK(batched_entropy_ ##type.lock), \ + .position = UINT_MAX \ +}; \ + \ +type get_random_ ##type(void) \ +{ \ + type ret; \ + unsigned long flags; \ + struct batch_ ##type *batch; \ + unsigned long next_gen; \ + \ + warn_unseeded_randomness(); \ + \ + if (!crng_ready()) { \ + _get_random_bytes(&ret, sizeof(ret)); \ + return ret; \ + } \ + \ + local_lock_irqsave(&batched_entropy_ ##type.lock, flags); \ + batch = raw_cpu_ptr(&batched_entropy_##type); \ + \ + next_gen = READ_ONCE(base_crng.generation); \ + if (batch->position >= ARRAY_SIZE(batch->entropy) || \ + next_gen != batch->generation) { \ + _get_random_bytes(batch->entropy, sizeof(batch->entropy)); \ + batch->position = 0; \ + batch->generation = next_gen; \ + } \ + \ + ret = batch->entropy[batch->position]; \ + batch->entropy[batch->position] = 0; \ + ++batch->position; \ + local_unlock_irqrestore(&batched_entropy_ ##type.lock, flags); \ + return ret; \ +} \ +EXPORT_SYMBOL(get_random_ ##type); + +DEFINE_BATCHED_ENTROPY(u64) +DEFINE_BATCHED_ENTROPY(u32) #ifdef CONFIG_SMP /* * This function is called when the CPU is coming up, with entry * CPUHP_RANDOM_PREPARE, which comes before CPUHP_WORKQUEUE_PREP. */ -int random_prepare_cpu(unsigned int cpu) +int __cold random_prepare_cpu(unsigned int cpu) { /* * When the cpu comes back online, immediately invalidate both @@ -696,65 +528,6 @@ int random_prepare_cpu(unsigned int cpu) } #endif -/** - * randomize_page - Generate a random, page aligned address - * @start: The smallest acceptable address the caller will take. - * @range: The size of the area, starting at @start, within which the - * random address must fall. - * - * If @start + @range would overflow, @range is capped. - * - * NOTE: Historical use of randomize_range, which this replaces, presumed that - * @start was already page aligned. We now align it regardless. - * - * Return: A page aligned address within [start, start + range). On error, - * @start is returned. - */ -unsigned long randomize_page(unsigned long start, unsigned long range) -{ - if (!PAGE_ALIGNED(start)) { - range -= PAGE_ALIGN(start) - start; - start = PAGE_ALIGN(start); - } - - if (start > ULONG_MAX - range) - range = ULONG_MAX - start; - - range >>= PAGE_SHIFT; - - if (range == 0) - return start; - - return start + (get_random_long() % range << PAGE_SHIFT); -} - -/* - * This function will use the architecture-specific hardware random - * number generator if it is available. It is not recommended for - * use. Use get_random_bytes() instead. It returns the number of - * bytes filled in. - */ -size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes) -{ - size_t left = nbytes; - u8 *p = buf; - - while (left) { - unsigned long v; - size_t chunk = min_t(size_t, left, sizeof(unsigned long)); - - if (!arch_get_random_long(&v)) - break; - - memcpy(p, &v, chunk); - p += chunk; - left -= chunk; - } - - return nbytes - left; -} -EXPORT_SYMBOL(get_random_bytes_arch); - /********************************************************************** * @@ -762,33 +535,28 @@ EXPORT_SYMBOL(get_random_bytes_arch); * * Callers may add entropy via: * - * static void mix_pool_bytes(const void *in, size_t nbytes) + * static void mix_pool_bytes(const void *buf, size_t len) * * After which, if added entropy should be credited: * - * static void credit_entropy_bits(size_t nbits) + * static void credit_init_bits(size_t bits) * - * Finally, extract entropy via these two, with the latter one - * setting the entropy count to zero and extracting only if there - * is POOL_MIN_BITS entropy credited prior or force is true: + * Finally, extract entropy via: * - * static void extract_entropy(void *buf, size_t nbytes) - * static bool drain_entropy(void *buf, size_t nbytes, bool force) + * static void extract_entropy(void *buf, size_t len) * **********************************************************************/ enum { POOL_BITS = BLAKE2S_HASH_SIZE * 8, - POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */ + POOL_READY_BITS = POOL_BITS, /* When crng_init->CRNG_READY */ + POOL_EARLY_BITS = POOL_READY_BITS / 2 /* When crng_init->CRNG_EARLY */ }; -/* For notifying userspace should write into /dev/random. */ -static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); - static struct { struct blake2s_state hash; spinlock_t lock; - unsigned int entropy_count; + unsigned int init_bits; } input_pool = { .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE), BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4, @@ -797,48 +565,30 @@ static struct { .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), }; -static void _mix_pool_bytes(const void *in, size_t nbytes) +static void _mix_pool_bytes(const void *buf, size_t len) { - blake2s_update(&input_pool.hash, in, nbytes); + blake2s_update(&input_pool.hash, buf, len); } /* - * This function adds bytes into the entropy "pool". It does not - * update the entropy estimate. The caller should call - * credit_entropy_bits if this is appropriate. + * This function adds bytes into the input pool. It does not + * update the initialization bit counter; the caller should call + * credit_init_bits if this is appropriate. */ -static void mix_pool_bytes(const void *in, size_t nbytes) +static void mix_pool_bytes(const void *buf, size_t len) { unsigned long flags; spin_lock_irqsave(&input_pool.lock, flags); - _mix_pool_bytes(in, nbytes); + _mix_pool_bytes(buf, len); spin_unlock_irqrestore(&input_pool.lock, flags); } -static void credit_entropy_bits(size_t nbits) -{ - unsigned int entropy_count, orig, add; - - if (!nbits) - return; - - add = min_t(size_t, nbits, POOL_BITS); - - do { - orig = READ_ONCE(input_pool.entropy_count); - entropy_count = min_t(unsigned int, POOL_BITS, orig + add); - } while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig); - - if (!crng_ready() && entropy_count >= POOL_MIN_BITS) - crng_reseed(false); -} - /* * This is an HKDF-like construction for using the hashed collected entropy * as a PRF key, that's then expanded block-by-block. */ -static void extract_entropy(void *buf, size_t nbytes) +static void extract_entropy(void *buf, size_t len) { unsigned long flags; u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE]; @@ -867,12 +617,12 @@ static void extract_entropy(void *buf, size_t nbytes) spin_unlock_irqrestore(&input_pool.lock, flags); memzero_explicit(next_key, sizeof(next_key)); - while (nbytes) { - i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE); + while (len) { + i = min_t(size_t, len, BLAKE2S_HASH_SIZE); /* output = HASHPRF(seed, RDSEED || ++counter) */ ++block.counter; blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed)); - nbytes -= i; + len -= i; buf += i; } @@ -880,23 +630,42 @@ static void extract_entropy(void *buf, size_t nbytes) memzero_explicit(&block, sizeof(block)); } -/* - * First we make sure we have POOL_MIN_BITS of entropy in the pool unless force - * is true, and then we set the entropy count to zero (but don't actually touch - * any data). Only then can we extract a new key with extract_entropy(). - */ -static bool drain_entropy(void *buf, size_t nbytes, bool force) +#define credit_init_bits(bits) if (!crng_ready()) _credit_init_bits(bits) + +static void __cold _credit_init_bits(size_t bits) { - unsigned int entropy_count; + static struct execute_work set_ready; + unsigned int new, orig, add; + unsigned long flags; + + if (!bits) + return; + + add = min_t(size_t, bits, POOL_BITS); + do { - entropy_count = READ_ONCE(input_pool.entropy_count); - if (!force && entropy_count < POOL_MIN_BITS) - return false; - } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count); - extract_entropy(buf, nbytes); - wake_up_interruptible(&random_write_wait); - kill_fasync(&fasync, SIGIO, POLL_OUT); - return true; + orig = READ_ONCE(input_pool.init_bits); + new = min_t(unsigned int, POOL_BITS, orig + add); + } while (cmpxchg(&input_pool.init_bits, orig, new) != orig); + + if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) { + crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */ + execute_in_process_context(crng_set_ready, &set_ready); + wake_up_interruptible(&crng_init_wait); + kill_fasync(&fasync, SIGIO, POLL_IN); + pr_notice("crng init done\n"); + if (urandom_warning.missed) + pr_notice("%d urandom warning(s) missed due to ratelimiting\n", + urandom_warning.missed); + } else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) { + spin_lock_irqsave(&base_crng.lock, flags); + /* Check if crng_init is CRNG_EMPTY, to avoid race with crng_reseed(). */ + if (crng_init == CRNG_EMPTY) { + extract_entropy(base_crng.key, sizeof(base_crng.key)); + crng_init = CRNG_EARLY; + } + spin_unlock_irqrestore(&base_crng.lock, flags); + } } @@ -907,15 +676,13 @@ static bool drain_entropy(void *buf, size_t nbytes, bool force) * The following exported functions are used for pushing entropy into * the above entropy accumulation routines: * - * void add_device_randomness(const void *buf, size_t size); - * void add_input_randomness(unsigned int type, unsigned int code, - * unsigned int value); - * void add_disk_randomness(struct gendisk *disk); - * void add_hwgenerator_randomness(const void *buffer, size_t count, - * size_t entropy); - * void add_bootloader_randomness(const void *buf, size_t size); - * void add_vmfork_randomness(const void *unique_vm_id, size_t size); + * void add_device_randomness(const void *buf, size_t len); + * void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy); + * void add_bootloader_randomness(const void *buf, size_t len); + * void add_vmfork_randomness(const void *unique_vm_id, size_t len); * void add_interrupt_randomness(int irq); + * void add_input_randomness(unsigned int type, unsigned int code, unsigned int value); + * void add_disk_randomness(struct gendisk *disk); * * add_device_randomness() adds data to the input pool that * is likely to differ between two devices (or possibly even per boot). @@ -925,26 +692,13 @@ static bool drain_entropy(void *buf, size_t nbytes, bool force) * that might otherwise be identical and have very little entropy * available to them (particularly common in the embedded world). * - * add_input_randomness() uses the input layer interrupt timing, as well - * as the event type information from the hardware. - * - * add_disk_randomness() uses what amounts to the seek time of block - * layer request events, on a per-disk_devt basis, as input to the - * entropy pool. Note that high-speed solid state drives with very low - * seek times do not make for good sources of entropy, as their seek - * times are usually fairly consistent. - * - * The above two routines try to estimate how many bits of entropy - * to credit. They do this by keeping track of the first and second - * order deltas of the event timings. - * * add_hwgenerator_randomness() is for true hardware RNGs, and will credit * entropy as specified by the caller. If the entropy pool is full it will * block until more entropy is needed. * - * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or - * add_device_randomness(), depending on whether or not the configuration - * option CONFIG_RANDOM_TRUST_BOOTLOADER is set. + * add_bootloader_randomness() is called by bootloader drivers, such as EFI + * and device tree, and credits its input depending on whether or not the + * configuration option CONFIG_RANDOM_TRUST_BOOTLOADER is set. * * add_vmfork_randomness() adds a unique (but not necessarily secret) ID * representing the current instance of a VM to the pool, without crediting, @@ -955,8 +709,22 @@ static bool drain_entropy(void *buf, size_t nbytes, bool force) * as inputs, it feeds the input pool roughly once a second or after 64 * interrupts, crediting 1 bit of entropy for whichever comes first. * + * add_input_randomness() uses the input layer interrupt timing, as well + * as the event type information from the hardware. + * + * add_disk_randomness() uses what amounts to the seek time of block + * layer request events, on a per-disk_devt basis, as input to the + * entropy pool. Note that high-speed solid state drives with very low + * seek times do not make for good sources of entropy, as their seek + * times are usually fairly consistent. + * + * The last two routines try to estimate how many bits of entropy + * to credit. They do this by keeping track of the first and second + * order deltas of the event timings. + * **********************************************************************/ +static bool used_arch_random; static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); static bool trust_bootloader __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER); static int __init parse_trust_cpu(char *arg) @@ -970,52 +738,91 @@ static int __init parse_trust_bootloader(char *arg) early_param("random.trust_cpu", parse_trust_cpu); early_param("random.trust_bootloader", parse_trust_bootloader); +static int random_pm_notification(struct notifier_block *nb, unsigned long action, void *data) +{ + unsigned long flags, entropy = random_get_entropy(); + + /* + * Encode a representation of how long the system has been suspended, + * in a way that is distinct from prior system suspends. + */ + ktime_t stamps[] = { ktime_get(), ktime_get_boottime(), ktime_get_real() }; + + spin_lock_irqsave(&input_pool.lock, flags); + _mix_pool_bytes(&action, sizeof(action)); + _mix_pool_bytes(stamps, sizeof(stamps)); + _mix_pool_bytes(&entropy, sizeof(entropy)); + spin_unlock_irqrestore(&input_pool.lock, flags); + + if (crng_ready() && (action == PM_RESTORE_PREPARE || + (action == PM_POST_SUSPEND && + !IS_ENABLED(CONFIG_PM_AUTOSLEEP) && !IS_ENABLED(CONFIG_ANDROID)))) { + crng_reseed(); + pr_notice("crng reseeded on system resumption\n"); + } + return 0; +} + +static struct notifier_block pm_notifier = { .notifier_call = random_pm_notification }; + /* * The first collection of entropy occurs at system boot while interrupts - * are still turned off. Here we push in RDSEED, a timestamp, and utsname(). - * Depending on the above configuration knob, RDSEED may be considered - * sufficient for initialization. Note that much earlier setup may already - * have pushed entropy into the input pool by the time we get here. + * are still turned off. Here we push in latent entropy, RDSEED, a timestamp, + * utsname(), and the command line. Depending on the above configuration knob, + * RDSEED may be considered sufficient for initialization. Note that much + * earlier setup may already have pushed entropy into the input pool by the + * time we get here. */ -int __init rand_initialize(void) +int __init random_init(const char *command_line) { - size_t i; ktime_t now = ktime_get_real(); - bool arch_init = true; - unsigned long rv; + unsigned int i, arch_bytes; + unsigned long entropy; #if defined(LATENT_ENTROPY_PLUGIN) static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy; _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed)); #endif - for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) { - if (!arch_get_random_seed_long_early(&rv) && - !arch_get_random_long_early(&rv)) { - rv = random_get_entropy(); - arch_init = false; + for (i = 0, arch_bytes = BLAKE2S_BLOCK_SIZE; + i < BLAKE2S_BLOCK_SIZE; i += sizeof(entropy)) { + if (!arch_get_random_seed_long_early(&entropy) && + !arch_get_random_long_early(&entropy)) { + entropy = random_get_entropy(); + arch_bytes -= sizeof(entropy); } - _mix_pool_bytes(&rv, sizeof(rv)); + _mix_pool_bytes(&entropy, sizeof(entropy)); } _mix_pool_bytes(&now, sizeof(now)); _mix_pool_bytes(utsname(), sizeof(*(utsname()))); + _mix_pool_bytes(command_line, strlen(command_line)); + add_latent_entropy(); - extract_entropy(base_crng.key, sizeof(base_crng.key)); - ++base_crng.generation; + if (crng_ready()) + crng_reseed(); + else if (trust_cpu) + credit_init_bits(arch_bytes * 8); + used_arch_random = arch_bytes * 8 >= POOL_READY_BITS; - if (arch_init && trust_cpu && !crng_ready()) { - crng_init = 2; - pr_notice("crng init done (trusting CPU's manufacturer)\n"); - } + WARN_ON(register_pm_notifier(&pm_notifier)); - if (ratelimit_disable) { - urandom_warning.interval = 0; - unseeded_warning.interval = 0; - } + WARN(!random_get_entropy(), "Missing cycle counter and fallback timer; RNG " + "entropy collection will consequently suffer."); return 0; } /* + * Returns whether arch randomness has been mixed into the initial + * state of the RNG, regardless of whether or not that randomness + * was credited. Knowing this is only good for a very limited set + * of uses, such as early init printk pointer obfuscation. + */ +bool rng_has_arch_random(void) +{ + return used_arch_random; +} + +/* * Add device- or boot-specific data to the input pool to help * initialize it. * @@ -1023,164 +830,46 @@ int __init rand_initialize(void) * the entropy pool having similar initial state across largely * identical devices. */ -void add_device_randomness(const void *buf, size_t size) +void add_device_randomness(const void *buf, size_t len) { - unsigned long cycles = random_get_entropy(); - unsigned long flags, now = jiffies; - - if (crng_init == 0 && size) - crng_pre_init_inject(buf, size, false); + unsigned long entropy = random_get_entropy(); + unsigned long flags; spin_lock_irqsave(&input_pool.lock, flags); - _mix_pool_bytes(&cycles, sizeof(cycles)); - _mix_pool_bytes(&now, sizeof(now)); - _mix_pool_bytes(buf, size); + _mix_pool_bytes(&entropy, sizeof(entropy)); + _mix_pool_bytes(buf, len); spin_unlock_irqrestore(&input_pool.lock, flags); } EXPORT_SYMBOL(add_device_randomness); -/* There is one of these per entropy source */ -struct timer_rand_state { - unsigned long last_time; - long last_delta, last_delta2; -}; - -/* - * This function adds entropy to the entropy "pool" by using timing - * delays. It uses the timer_rand_state structure to make an estimate - * of how many bits of entropy this call has added to the pool. - * - * The number "num" is also added to the pool - it should somehow describe - * the type of event which just happened. This is currently 0-255 for - * keyboard scan codes, and 256 upwards for interrupts. - */ -static void add_timer_randomness(struct timer_rand_state *state, unsigned int num) -{ - unsigned long cycles = random_get_entropy(), now = jiffies, flags; - long delta, delta2, delta3; - - spin_lock_irqsave(&input_pool.lock, flags); - _mix_pool_bytes(&cycles, sizeof(cycles)); - _mix_pool_bytes(&now, sizeof(now)); - _mix_pool_bytes(&num, sizeof(num)); - spin_unlock_irqrestore(&input_pool.lock, flags); - - /* - * Calculate number of bits of randomness we probably added. - * We take into account the first, second and third-order deltas - * in order to make our estimate. - */ - delta = now - READ_ONCE(state->last_time); - WRITE_ONCE(state->last_time, now); - - delta2 = delta - READ_ONCE(state->last_delta); - WRITE_ONCE(state->last_delta, delta); - - delta3 = delta2 - READ_ONCE(state->last_delta2); - WRITE_ONCE(state->last_delta2, delta2); - - if (delta < 0) - delta = -delta; - if (delta2 < 0) - delta2 = -delta2; - if (delta3 < 0) - delta3 = -delta3; - if (delta > delta2) - delta = delta2; - if (delta > delta3) - delta = delta3; - - /* - * delta is now minimum absolute delta. - * Round down by 1 bit on general principles, - * and limit entropy estimate to 12 bits. - */ - credit_entropy_bits(min_t(unsigned int, fls(delta >> 1), 11)); -} - -void add_input_randomness(unsigned int type, unsigned int code, - unsigned int value) -{ - static unsigned char last_value; - static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES }; - - /* Ignore autorepeat and the like. */ - if (value == last_value) - return; - - last_value = value; - add_timer_randomness(&input_timer_state, - (type << 4) ^ code ^ (code >> 4) ^ value); -} -EXPORT_SYMBOL_GPL(add_input_randomness); - -#ifdef CONFIG_BLOCK -void add_disk_randomness(struct gendisk *disk) -{ - if (!disk || !disk->random) - return; - /* First major is 1, so we get >= 0x200 here. */ - add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); -} -EXPORT_SYMBOL_GPL(add_disk_randomness); - -void rand_initialize_disk(struct gendisk *disk) -{ - struct timer_rand_state *state; - - /* - * If kzalloc returns null, we just won't use that entropy - * source. - */ - state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); - if (state) { - state->last_time = INITIAL_JIFFIES; - disk->random = state; - } -} -#endif - /* * Interface for in-kernel drivers of true hardware RNGs. * Those devices may produce endless random bits and will be throttled * when our pool is full. */ -void add_hwgenerator_randomness(const void *buffer, size_t count, - size_t entropy) +void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy) { - if (unlikely(crng_init == 0 && entropy < POOL_MIN_BITS)) { - crng_pre_init_inject(buffer, count, true); - mix_pool_bytes(buffer, count); - return; - } + mix_pool_bytes(buf, len); + credit_init_bits(entropy); /* - * Throttle writing if we're above the trickle threshold. - * We'll be woken up again once below POOL_MIN_BITS, when - * the calling thread is about to terminate, or once - * CRNG_RESEED_INTERVAL has elapsed. + * Throttle writing to once every CRNG_RESEED_INTERVAL, unless + * we're not yet initialized. */ - wait_event_interruptible_timeout(random_write_wait, - !system_wq || kthread_should_stop() || - input_pool.entropy_count < POOL_MIN_BITS, - CRNG_RESEED_INTERVAL); - mix_pool_bytes(buffer, count); - credit_entropy_bits(entropy); + if (!kthread_should_stop() && crng_ready()) + schedule_timeout_interruptible(CRNG_RESEED_INTERVAL); } EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); /* - * Handle random seed passed by bootloader. - * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise - * it would be regarded as device data. - * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. + * Handle random seed passed by bootloader, and credit it if + * CONFIG_RANDOM_TRUST_BOOTLOADER is set. */ -void add_bootloader_randomness(const void *buf, size_t size) +void __cold add_bootloader_randomness(const void *buf, size_t len) { + mix_pool_bytes(buf, len); if (trust_bootloader) - add_hwgenerator_randomness(buf, size, size * 8); - else - add_device_randomness(buf, size); + credit_init_bits(len * 8); } EXPORT_SYMBOL_GPL(add_bootloader_randomness); @@ -1192,11 +881,11 @@ static BLOCKING_NOTIFIER_HEAD(vmfork_chain); * don't credit it, but we do immediately force a reseed after so * that it's used by the crng posthaste. */ -void add_vmfork_randomness(const void *unique_vm_id, size_t size) +void __cold add_vmfork_randomness(const void *unique_vm_id, size_t len) { - add_device_randomness(unique_vm_id, size); + add_device_randomness(unique_vm_id, len); if (crng_ready()) { - crng_reseed(true); + crng_reseed(); pr_notice("crng reseeded due to virtual machine fork\n"); } blocking_notifier_call_chain(&vmfork_chain, 0, NULL); @@ -1205,13 +894,13 @@ void add_vmfork_randomness(const void *unique_vm_id, size_t size) EXPORT_SYMBOL_GPL(add_vmfork_randomness); #endif -int register_random_vmfork_notifier(struct notifier_block *nb) +int __cold register_random_vmfork_notifier(struct notifier_block *nb) { return blocking_notifier_chain_register(&vmfork_chain, nb); } EXPORT_SYMBOL_GPL(register_random_vmfork_notifier); -int unregister_random_vmfork_notifier(struct notifier_block *nb) +int __cold unregister_random_vmfork_notifier(struct notifier_block *nb) { return blocking_notifier_chain_unregister(&vmfork_chain, nb); } @@ -1223,17 +912,15 @@ struct fast_pool { unsigned long pool[4]; unsigned long last; unsigned int count; - u16 reg_idx; }; static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = { #ifdef CONFIG_64BIT - /* SipHash constants */ - .pool = { 0x736f6d6570736575UL, 0x646f72616e646f6dUL, - 0x6c7967656e657261UL, 0x7465646279746573UL } +#define FASTMIX_PERM SIPHASH_PERMUTATION + .pool = { SIPHASH_CONST_0, SIPHASH_CONST_1, SIPHASH_CONST_2, SIPHASH_CONST_3 } #else - /* HalfSipHash constants */ - .pool = { 0, 0, 0x6c796765U, 0x74656462U } +#define FASTMIX_PERM HSIPHASH_PERMUTATION + .pool = { HSIPHASH_CONST_0, HSIPHASH_CONST_1, HSIPHASH_CONST_2, HSIPHASH_CONST_3 } #endif }; @@ -1241,27 +928,16 @@ static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = { * This is [Half]SipHash-1-x, starting from an empty key. Because * the key is fixed, it assumes that its inputs are non-malicious, * and therefore this has no security on its own. s represents the - * 128 or 256-bit SipHash state, while v represents a 128-bit input. + * four-word SipHash state, while v represents a two-word input. */ -static void fast_mix(unsigned long s[4], const unsigned long *v) +static void fast_mix(unsigned long s[4], unsigned long v1, unsigned long v2) { - size_t i; - - for (i = 0; i < 16 / sizeof(long); ++i) { - s[3] ^= v[i]; -#ifdef CONFIG_64BIT - s[0] += s[1]; s[1] = rol64(s[1], 13); s[1] ^= s[0]; s[0] = rol64(s[0], 32); - s[2] += s[3]; s[3] = rol64(s[3], 16); s[3] ^= s[2]; - s[0] += s[3]; s[3] = rol64(s[3], 21); s[3] ^= s[0]; - s[2] += s[1]; s[1] = rol64(s[1], 17); s[1] ^= s[2]; s[2] = rol64(s[2], 32); -#else - s[0] += s[1]; s[1] = rol32(s[1], 5); s[1] ^= s[0]; s[0] = rol32(s[0], 16); - s[2] += s[3]; s[3] = rol32(s[3], 8); s[3] ^= s[2]; - s[0] += s[3]; s[3] = rol32(s[3], 7); s[3] ^= s[0]; - s[2] += s[1]; s[1] = rol32(s[1], 13); s[1] ^= s[2]; s[2] = rol32(s[2], 16); -#endif - s[0] ^= v[i]; - } + s[3] ^= v1; + FASTMIX_PERM(s[0], s[1], s[2], s[3]); + s[0] ^= v1; + s[3] ^= v2; + FASTMIX_PERM(s[0], s[1], s[2], s[3]); + s[0] ^= v2; } #ifdef CONFIG_SMP @@ -1269,7 +945,7 @@ static void fast_mix(unsigned long s[4], const unsigned long *v) * This function is called when the CPU has just come online, with * entry CPUHP_AP_RANDOM_ONLINE, just after CPUHP_AP_WORKQUEUE_ONLINE. */ -int random_online_cpu(unsigned int cpu) +int __cold random_online_cpu(unsigned int cpu) { /* * During CPU shutdown and before CPU onlining, add_interrupt_ @@ -1287,33 +963,18 @@ int random_online_cpu(unsigned int cpu) } #endif -static unsigned long get_reg(struct fast_pool *f, struct pt_regs *regs) -{ - unsigned long *ptr = (unsigned long *)regs; - unsigned int idx; - - if (regs == NULL) - return 0; - idx = READ_ONCE(f->reg_idx); - if (idx >= sizeof(struct pt_regs) / sizeof(unsigned long)) - idx = 0; - ptr += idx++; - WRITE_ONCE(f->reg_idx, idx); - return *ptr; -} - static void mix_interrupt_randomness(struct work_struct *work) { struct fast_pool *fast_pool = container_of(work, struct fast_pool, mix); /* - * The size of the copied stack pool is explicitly 16 bytes so that we - * tax mix_pool_byte()'s compression function the same amount on all - * platforms. This means on 64-bit we copy half the pool into this, - * while on 32-bit we copy all of it. The entropy is supposed to be - * sufficiently dispersed between bits that in the sponge-like - * half case, on average we don't wind up "losing" some. + * The size of the copied stack pool is explicitly 2 longs so that we + * only ever ingest half of the siphash output each time, retaining + * the other half as the next "key" that carries over. The entropy is + * supposed to be sufficiently dispersed between bits so on average + * we don't wind up "losing" some. */ - u8 pool[16]; + unsigned long pool[2]; + unsigned int count; /* Check to see if we're running on the wrong CPU due to hotplug. */ local_irq_disable(); @@ -1327,17 +988,13 @@ static void mix_interrupt_randomness(struct work_struct *work) * consistent view, before we reenable irqs again. */ memcpy(pool, fast_pool->pool, sizeof(pool)); + count = fast_pool->count; fast_pool->count = 0; fast_pool->last = jiffies; local_irq_enable(); - if (unlikely(crng_init == 0)) { - crng_pre_init_inject(pool, sizeof(pool), true); - mix_pool_bytes(pool, sizeof(pool)); - } else { - mix_pool_bytes(pool, sizeof(pool)); - credit_entropy_bits(1); - } + mix_pool_bytes(pool, sizeof(pool)); + credit_init_bits(max(1u, (count & U16_MAX) / 64)); memzero_explicit(pool, sizeof(pool)); } @@ -1345,37 +1002,19 @@ static void mix_interrupt_randomness(struct work_struct *work) void add_interrupt_randomness(int irq) { enum { MIX_INFLIGHT = 1U << 31 }; - unsigned long cycles = random_get_entropy(), now = jiffies; + unsigned long entropy = random_get_entropy(); struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); struct pt_regs *regs = get_irq_regs(); unsigned int new_count; - union { - u32 u32[4]; - u64 u64[2]; - unsigned long longs[16 / sizeof(long)]; - } irq_data; - - if (cycles == 0) - cycles = get_reg(fast_pool, regs); - - if (sizeof(unsigned long) == 8) { - irq_data.u64[0] = cycles ^ rol64(now, 32) ^ irq; - irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_; - } else { - irq_data.u32[0] = cycles ^ irq; - irq_data.u32[1] = now; - irq_data.u32[2] = regs ? instruction_pointer(regs) : _RET_IP_; - irq_data.u32[3] = get_reg(fast_pool, regs); - } - fast_mix(fast_pool->pool, irq_data.longs); + fast_mix(fast_pool->pool, entropy, + (regs ? instruction_pointer(regs) : _RET_IP_) ^ swab(irq)); new_count = ++fast_pool->count; if (new_count & MIX_INFLIGHT) return; - if (new_count < 64 && (!time_after(now, fast_pool->last + HZ) || - unlikely(crng_init == 0))) + if (new_count < 64 && !time_is_before_jiffies(fast_pool->last + HZ)) return; if (unlikely(!fast_pool->mix.func)) @@ -1385,6 +1024,132 @@ void add_interrupt_randomness(int irq) } EXPORT_SYMBOL_GPL(add_interrupt_randomness); +/* There is one of these per entropy source */ +struct timer_rand_state { + unsigned long last_time; + long last_delta, last_delta2; +}; + +/* + * This function adds entropy to the entropy "pool" by using timing + * delays. It uses the timer_rand_state structure to make an estimate + * of how many bits of entropy this call has added to the pool. The + * value "num" is also added to the pool; it should somehow describe + * the type of event that just happened. + */ +static void add_timer_randomness(struct timer_rand_state *state, unsigned int num) +{ + unsigned long entropy = random_get_entropy(), now = jiffies, flags; + long delta, delta2, delta3; + unsigned int bits; + + /* + * If we're in a hard IRQ, add_interrupt_randomness() will be called + * sometime after, so mix into the fast pool. + */ + if (in_hardirq()) { + fast_mix(this_cpu_ptr(&irq_randomness)->pool, entropy, num); + } else { + spin_lock_irqsave(&input_pool.lock, flags); + _mix_pool_bytes(&entropy, sizeof(entropy)); + _mix_pool_bytes(&num, sizeof(num)); + spin_unlock_irqrestore(&input_pool.lock, flags); + } + + if (crng_ready()) + return; + + /* + * Calculate number of bits of randomness we probably added. + * We take into account the first, second and third-order deltas + * in order to make our estimate. + */ + delta = now - READ_ONCE(state->last_time); + WRITE_ONCE(state->last_time, now); + + delta2 = delta - READ_ONCE(state->last_delta); + WRITE_ONCE(state->last_delta, delta); + + delta3 = delta2 - READ_ONCE(state->last_delta2); + WRITE_ONCE(state->last_delta2, delta2); + + if (delta < 0) + delta = -delta; + if (delta2 < 0) + delta2 = -delta2; + if (delta3 < 0) + delta3 = -delta3; + if (delta > delta2) + delta = delta2; + if (delta > delta3) + delta = delta3; + + /* + * delta is now minimum absolute delta. Round down by 1 bit + * on general principles, and limit entropy estimate to 11 bits. + */ + bits = min(fls(delta >> 1), 11); + + /* + * As mentioned above, if we're in a hard IRQ, add_interrupt_randomness() + * will run after this, which uses a different crediting scheme of 1 bit + * per every 64 interrupts. In order to let that function do accounting + * close to the one in this function, we credit a full 64/64 bit per bit, + * and then subtract one to account for the extra one added. + */ + if (in_hardirq()) + this_cpu_ptr(&irq_randomness)->count += max(1u, bits * 64) - 1; + else + _credit_init_bits(bits); +} + +void add_input_randomness(unsigned int type, unsigned int code, unsigned int value) +{ + static unsigned char last_value; + static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES }; + + /* Ignore autorepeat and the like. */ + if (value == last_value) + return; + + last_value = value; + add_timer_randomness(&input_timer_state, + (type << 4) ^ code ^ (code >> 4) ^ value); +} +EXPORT_SYMBOL_GPL(add_input_randomness); + +#ifdef CONFIG_BLOCK +void add_disk_randomness(struct gendisk *disk) +{ + if (!disk || !disk->random) + return; + /* First major is 1, so we get >= 0x200 here. */ + add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); +} +EXPORT_SYMBOL_GPL(add_disk_randomness); + +void __cold rand_initialize_disk(struct gendisk *disk) +{ + struct timer_rand_state *state; + + /* + * If kzalloc returns null, we just won't use that entropy + * source. + */ + state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); + if (state) { + state->last_time = INITIAL_JIFFIES; + disk->random = state; + } +} +#endif + +struct entropy_timer_state { + unsigned long entropy; + struct timer_list timer; + unsigned int samples, samples_per_bit; +}; + /* * Each time the timer fires, we expect that we got an unpredictable * jump in the cycle counter. Even if the timer is running on another @@ -1398,40 +1163,50 @@ EXPORT_SYMBOL_GPL(add_interrupt_randomness); * * So the re-arming always happens in the entropy loop itself. */ -static void entropy_timer(struct timer_list *t) +static void __cold entropy_timer(struct timer_list *timer) { - credit_entropy_bits(1); + struct entropy_timer_state *state = container_of(timer, struct entropy_timer_state, timer); + + if (++state->samples == state->samples_per_bit) { + credit_init_bits(1); + state->samples = 0; + } } /* * If we have an actual cycle counter, see if we can * generate enough entropy with timing noise */ -static void try_to_generate_entropy(void) +static void __cold try_to_generate_entropy(void) { - struct { - unsigned long cycles; - struct timer_list timer; - } stack; - - stack.cycles = random_get_entropy(); - - /* Slow counter - or none. Don't even bother */ - if (stack.cycles == random_get_entropy()) + enum { NUM_TRIAL_SAMPLES = 8192, MAX_SAMPLES_PER_BIT = 32 }; + struct entropy_timer_state stack; + unsigned int i, num_different = 0; + unsigned long last = random_get_entropy(); + + for (i = 0; i < NUM_TRIAL_SAMPLES - 1; ++i) { + stack.entropy = random_get_entropy(); + if (stack.entropy != last) + ++num_different; + last = stack.entropy; + } + stack.samples_per_bit = DIV_ROUND_UP(NUM_TRIAL_SAMPLES, num_different + 1); + if (stack.samples_per_bit > MAX_SAMPLES_PER_BIT) return; + stack.samples = 0; timer_setup_on_stack(&stack.timer, entropy_timer, 0); while (!crng_ready() && !signal_pending(current)) { if (!timer_pending(&stack.timer)) mod_timer(&stack.timer, jiffies + 1); - mix_pool_bytes(&stack.cycles, sizeof(stack.cycles)); + mix_pool_bytes(&stack.entropy, sizeof(stack.entropy)); schedule(); - stack.cycles = random_get_entropy(); + stack.entropy = random_get_entropy(); } del_timer_sync(&stack.timer); destroy_timer_on_stack(&stack.timer); - mix_pool_bytes(&stack.cycles, sizeof(stack.cycles)); + mix_pool_bytes(&stack.entropy, sizeof(stack.entropy)); } @@ -1463,9 +1238,12 @@ static void try_to_generate_entropy(void) * **********************************************************************/ -SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int, - flags) +SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags) { + struct iov_iter iter; + struct iovec iov; + int ret; + if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) return -EINVAL; @@ -1476,72 +1254,60 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int, if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM)) return -EINVAL; - if (count > INT_MAX) - count = INT_MAX; - - if (!(flags & GRND_INSECURE) && !crng_ready()) { - int ret; - + if (!crng_ready() && !(flags & GRND_INSECURE)) { if (flags & GRND_NONBLOCK) return -EAGAIN; ret = wait_for_random_bytes(); if (unlikely(ret)) return ret; } - return get_random_bytes_user(buf, count); + + ret = import_single_range(READ, ubuf, len, &iov, &iter); + if (unlikely(ret)) + return ret; + return get_random_bytes_user(&iter); } static __poll_t random_poll(struct file *file, poll_table *wait) { - __poll_t mask; - poll_wait(file, &crng_init_wait, wait); - poll_wait(file, &random_write_wait, wait); - mask = 0; - if (crng_ready()) - mask |= EPOLLIN | EPOLLRDNORM; - if (input_pool.entropy_count < POOL_MIN_BITS) - mask |= EPOLLOUT | EPOLLWRNORM; - return mask; + return crng_ready() ? EPOLLIN | EPOLLRDNORM : EPOLLOUT | EPOLLWRNORM; } -static int write_pool(const char __user *ubuf, size_t count) +static ssize_t write_pool_user(struct iov_iter *iter) { - size_t len; - int ret = 0; u8 block[BLAKE2S_BLOCK_SIZE]; + ssize_t ret = 0; + size_t copied; + + if (unlikely(!iov_iter_count(iter))) + return 0; + + for (;;) { + copied = copy_from_iter(block, sizeof(block), iter); + ret += copied; + mix_pool_bytes(block, copied); + if (!iov_iter_count(iter) || copied != sizeof(block)) + break; - while (count) { - len = min(count, sizeof(block)); - if (copy_from_user(block, ubuf, len)) { - ret = -EFAULT; - goto out; + BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0); + if (ret % PAGE_SIZE == 0) { + if (signal_pending(current)) + break; + cond_resched(); } - count -= len; - ubuf += len; - mix_pool_bytes(block, len); - cond_resched(); } -out: memzero_explicit(block, sizeof(block)); - return ret; + return ret ? ret : -EFAULT; } -static ssize_t random_write(struct file *file, const char __user *buffer, - size_t count, loff_t *ppos) +static ssize_t random_write_iter(struct kiocb *kiocb, struct iov_iter *iter) { - int ret; - - ret = write_pool(buffer, count); - if (ret) - return ret; - - return (ssize_t)count; + return write_pool_user(iter); } -static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes, - loff_t *ppos) +static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *iter) { static int maxwarn = 10; @@ -1552,37 +1318,38 @@ static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes, if (!crng_ready()) try_to_generate_entropy(); - if (!crng_ready() && maxwarn > 0) { - maxwarn--; - if (__ratelimit(&urandom_warning)) - pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", - current->comm, nbytes); + if (!crng_ready()) { + if (!ratelimit_disable && maxwarn <= 0) + ++urandom_warning.missed; + else if (ratelimit_disable || __ratelimit(&urandom_warning)) { + --maxwarn; + pr_notice("%s: uninitialized urandom read (%zu bytes read)\n", + current->comm, iov_iter_count(iter)); + } } - return get_random_bytes_user(buf, nbytes); + return get_random_bytes_user(iter); } -static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes, - loff_t *ppos) +static ssize_t random_read_iter(struct kiocb *kiocb, struct iov_iter *iter) { int ret; ret = wait_for_random_bytes(); if (ret != 0) return ret; - return get_random_bytes_user(buf, nbytes); + return get_random_bytes_user(iter); } static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) { - int size, ent_count; int __user *p = (int __user *)arg; - int retval; + int ent_count; switch (cmd) { case RNDGETENTCNT: /* Inherently racy, no point locking. */ - if (put_user(input_pool.entropy_count, p)) + if (put_user(input_pool.init_bits, p)) return -EFAULT; return 0; case RNDADDTOENTCNT: @@ -1592,41 +1359,46 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) return -EFAULT; if (ent_count < 0) return -EINVAL; - credit_entropy_bits(ent_count); + credit_init_bits(ent_count); return 0; - case RNDADDENTROPY: + case RNDADDENTROPY: { + struct iov_iter iter; + struct iovec iov; + ssize_t ret; + int len; + if (!capable(CAP_SYS_ADMIN)) return -EPERM; if (get_user(ent_count, p++)) return -EFAULT; if (ent_count < 0) return -EINVAL; - if (get_user(size, p++)) + if (get_user(len, p++)) return -EFAULT; - retval = write_pool((const char __user *)p, size); - if (retval < 0) - return retval; - credit_entropy_bits(ent_count); + ret = import_single_range(WRITE, p, len, &iov, &iter); + if (unlikely(ret)) + return ret; + ret = write_pool_user(&iter); + if (unlikely(ret < 0)) + return ret; + /* Since we're crediting, enforce that it was all written into the pool. */ + if (unlikely(ret != len)) + return -EFAULT; + credit_init_bits(ent_count); return 0; + } case RNDZAPENTCNT: case RNDCLEARPOOL: - /* - * Clear the entropy pool counters. We no longer clear - * the entropy pool, as that's silly. - */ + /* No longer has any effect. */ if (!capable(CAP_SYS_ADMIN)) return -EPERM; - if (xchg(&input_pool.entropy_count, 0) >= POOL_MIN_BITS) { - wake_up_interruptible(&random_write_wait); - kill_fasync(&fasync, SIGIO, POLL_OUT); - } return 0; case RNDRESEEDCRNG: if (!capable(CAP_SYS_ADMIN)) return -EPERM; if (!crng_ready()) return -ENODATA; - crng_reseed(false); + crng_reseed(); return 0; default: return -EINVAL; @@ -1639,22 +1411,26 @@ static int random_fasync(int fd, struct file *filp, int on) } const struct file_operations random_fops = { - .read = random_read, - .write = random_write, + .read_iter = random_read_iter, + .write_iter = random_write_iter, .poll = random_poll, .unlocked_ioctl = random_ioctl, .compat_ioctl = compat_ptr_ioctl, .fasync = random_fasync, .llseek = noop_llseek, + .splice_read = generic_file_splice_read, + .splice_write = iter_file_splice_write, }; const struct file_operations urandom_fops = { - .read = urandom_read, - .write = random_write, + .read_iter = urandom_read_iter, + .write_iter = random_write_iter, .unlocked_ioctl = random_ioctl, .compat_ioctl = compat_ptr_ioctl, .fasync = random_fasync, .llseek = noop_llseek, + .splice_read = generic_file_splice_read, + .splice_write = iter_file_splice_write, }; @@ -1678,7 +1454,7 @@ const struct file_operations urandom_fops = { * * - write_wakeup_threshold - the amount of entropy in the input pool * below which write polls to /dev/random will unblock, requesting - * more entropy, tied to the POOL_MIN_BITS constant. It is writable + * more entropy, tied to the POOL_READY_BITS constant. It is writable * to avoid breaking old userspaces, but writing to it does not * change any behavior of the RNG. * @@ -1693,7 +1469,7 @@ const struct file_operations urandom_fops = { #include <linux/sysctl.h> static int sysctl_random_min_urandom_seed = CRNG_RESEED_INTERVAL / HZ; -static int sysctl_random_write_wakeup_bits = POOL_MIN_BITS; +static int sysctl_random_write_wakeup_bits = POOL_READY_BITS; static int sysctl_poolsize = POOL_BITS; static u8 sysctl_bootid[UUID_SIZE]; @@ -1702,7 +1478,7 @@ static u8 sysctl_bootid[UUID_SIZE]; * UUID. The difference is in whether table->data is NULL; if it is, * then a new UUID is generated and returned to the user. */ -static int proc_do_uuid(struct ctl_table *table, int write, void *buffer, +static int proc_do_uuid(struct ctl_table *table, int write, void *buf, size_t *lenp, loff_t *ppos) { u8 tmp_uuid[UUID_SIZE], *uuid; @@ -1729,14 +1505,14 @@ static int proc_do_uuid(struct ctl_table *table, int write, void *buffer, } snprintf(uuid_string, sizeof(uuid_string), "%pU", uuid); - return proc_dostring(&fake_table, 0, buffer, lenp, ppos); + return proc_dostring(&fake_table, 0, buf, lenp, ppos); } /* The same as proc_dointvec, but writes don't change anything. */ -static int proc_do_rointvec(struct ctl_table *table, int write, void *buffer, +static int proc_do_rointvec(struct ctl_table *table, int write, void *buf, size_t *lenp, loff_t *ppos) { - return write ? 0 : proc_dointvec(table, 0, buffer, lenp, ppos); + return write ? 0 : proc_dointvec(table, 0, buf, lenp, ppos); } static struct ctl_table random_table[] = { @@ -1749,7 +1525,7 @@ static struct ctl_table random_table[] = { }, { .procname = "entropy_avail", - .data = &input_pool.entropy_count, + .data = &input_pool.init_bits, .maxlen = sizeof(int), .mode = 0444, .proc_handler = proc_dointvec, @@ -1783,8 +1559,8 @@ static struct ctl_table random_table[] = { }; /* - * rand_initialize() is called before sysctl_init(), - * so we cannot call register_sysctl_init() in rand_initialize() + * random_init() is called before sysctl_init(), + * so we cannot call register_sysctl_init() in random_init() */ static int __init random_sysctls_init(void) { diff --git a/include/linux/mm.h b/include/linux/mm.h index 9f44254af8ce..b0183450e484 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2677,6 +2677,7 @@ extern int install_special_mapping(struct mm_struct *mm, unsigned long flags, struct page **pages); unsigned long randomize_stack_top(unsigned long stack_top); +unsigned long randomize_page(unsigned long start, unsigned long range); extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); diff --git a/include/linux/prandom.h b/include/linux/prandom.h index 056d31317e49..deace5fb4e62 100644 --- a/include/linux/prandom.h +++ b/include/linux/prandom.h @@ -10,62 +10,16 @@ #include <linux/types.h> #include <linux/percpu.h> +#include <linux/random.h> -u32 prandom_u32(void); -void prandom_bytes(void *buf, size_t nbytes); -void prandom_seed(u32 seed); -void prandom_reseed_late(void); - -DECLARE_PER_CPU(unsigned long, net_rand_noise); - -#define PRANDOM_ADD_NOISE(a, b, c, d) \ - prandom_u32_add_noise((unsigned long)(a), (unsigned long)(b), \ - (unsigned long)(c), (unsigned long)(d)) - -#if BITS_PER_LONG == 64 -/* - * The core SipHash round function. Each line can be executed in - * parallel given enough CPU resources. - */ -#define PRND_SIPROUND(v0, v1, v2, v3) ( \ - v0 += v1, v1 = rol64(v1, 13), v2 += v3, v3 = rol64(v3, 16), \ - v1 ^= v0, v0 = rol64(v0, 32), v3 ^= v2, \ - v0 += v3, v3 = rol64(v3, 21), v2 += v1, v1 = rol64(v1, 17), \ - v3 ^= v0, v1 ^= v2, v2 = rol64(v2, 32) \ -) - -#define PRND_K0 (0x736f6d6570736575 ^ 0x6c7967656e657261) -#define PRND_K1 (0x646f72616e646f6d ^ 0x7465646279746573) - -#elif BITS_PER_LONG == 32 -/* - * On 32-bit machines, we use HSipHash, a reduced-width version of SipHash. - * This is weaker, but 32-bit machines are not used for high-traffic - * applications, so there is less output for an attacker to analyze. - */ -#define PRND_SIPROUND(v0, v1, v2, v3) ( \ - v0 += v1, v1 = rol32(v1, 5), v2 += v3, v3 = rol32(v3, 8), \ - v1 ^= v0, v0 = rol32(v0, 16), v3 ^= v2, \ - v0 += v3, v3 = rol32(v3, 7), v2 += v1, v1 = rol32(v1, 13), \ - v3 ^= v0, v1 ^= v2, v2 = rol32(v2, 16) \ -) -#define PRND_K0 0x6c796765 -#define PRND_K1 0x74656462 - -#else -#error Unsupported BITS_PER_LONG -#endif +static inline u32 prandom_u32(void) +{ + return get_random_u32(); +} -static inline void prandom_u32_add_noise(unsigned long a, unsigned long b, - unsigned long c, unsigned long d) +static inline void prandom_bytes(void *buf, size_t nbytes) { - /* - * This is not used cryptographically; it's just - * a convenient 4-word hash function. (3 xor, 2 add, 2 rol) - */ - a ^= raw_cpu_read(net_rand_noise); - PRND_SIPROUND(a, b, c, d); - raw_cpu_write(net_rand_noise, d); + return get_random_bytes(buf, nbytes); } struct rnd_state { @@ -117,7 +71,6 @@ static inline void prandom_seed_state(struct rnd_state *state, u64 seed) state->s2 = __seed(i, 8U); state->s3 = __seed(i, 16U); state->s4 = __seed(i, 128U); - PRANDOM_ADD_NOISE(state, i, 0, 0); } /* Pseudo random number generator from numerical recipes. */ diff --git a/include/linux/random.h b/include/linux/random.h index f673fbb838b3..fae0c84027fd 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -12,45 +12,32 @@ struct notifier_block; -extern void add_device_randomness(const void *, size_t); -extern void add_bootloader_randomness(const void *, size_t); +void add_device_randomness(const void *buf, size_t len); +void add_bootloader_randomness(const void *buf, size_t len); +void add_input_randomness(unsigned int type, unsigned int code, + unsigned int value) __latent_entropy; +void add_interrupt_randomness(int irq) __latent_entropy; +void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy); #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__) static inline void add_latent_entropy(void) { - add_device_randomness((const void *)&latent_entropy, - sizeof(latent_entropy)); + add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy)); } #else -static inline void add_latent_entropy(void) {} +static inline void add_latent_entropy(void) { } #endif -extern void add_input_randomness(unsigned int type, unsigned int code, - unsigned int value) __latent_entropy; -extern void add_interrupt_randomness(int irq) __latent_entropy; -extern void add_hwgenerator_randomness(const void *buffer, size_t count, - size_t entropy); #if IS_ENABLED(CONFIG_VMGENID) -extern void add_vmfork_randomness(const void *unique_vm_id, size_t size); -extern int register_random_vmfork_notifier(struct notifier_block *nb); -extern int unregister_random_vmfork_notifier(struct notifier_block *nb); +void add_vmfork_randomness(const void *unique_vm_id, size_t len); +int register_random_vmfork_notifier(struct notifier_block *nb); +int unregister_random_vmfork_notifier(struct notifier_block *nb); #else static inline int register_random_vmfork_notifier(struct notifier_block *nb) { return 0; } static inline int unregister_random_vmfork_notifier(struct notifier_block *nb) { return 0; } #endif -extern void get_random_bytes(void *buf, size_t nbytes); -extern int wait_for_random_bytes(void); -extern int __init rand_initialize(void); -extern bool rng_is_initialized(void); -extern int register_random_ready_notifier(struct notifier_block *nb); -extern int unregister_random_ready_notifier(struct notifier_block *nb); -extern size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes); - -#ifndef MODULE -extern const struct file_operations random_fops, urandom_fops; -#endif - +void get_random_bytes(void *buf, size_t len); u32 get_random_u32(void); u64 get_random_u64(void); static inline unsigned int get_random_int(void) @@ -82,11 +69,14 @@ static inline unsigned long get_random_long(void) static inline unsigned long get_random_canary(void) { - unsigned long val = get_random_long(); - - return val & CANARY_MASK; + return get_random_long() & CANARY_MASK; } +int __init random_init(const char *command_line); +bool rng_is_initialized(void); +bool rng_has_arch_random(void); +int wait_for_random_bytes(void); + /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes). * Returns the result of the call to wait_for_random_bytes. */ static inline int get_random_bytes_wait(void *buf, size_t nbytes) @@ -96,22 +86,20 @@ static inline int get_random_bytes_wait(void *buf, size_t nbytes) return ret; } -#define declare_get_random_var_wait(var) \ - static inline int get_random_ ## var ## _wait(var *out) { \ +#define declare_get_random_var_wait(name, ret_type) \ + static inline int get_random_ ## name ## _wait(ret_type *out) { \ int ret = wait_for_random_bytes(); \ if (unlikely(ret)) \ return ret; \ - *out = get_random_ ## var(); \ + *out = get_random_ ## name(); \ return 0; \ } -declare_get_random_var_wait(u32) -declare_get_random_var_wait(u64) -declare_get_random_var_wait(int) -declare_get_random_var_wait(long) +declare_get_random_var_wait(u32, u32) +declare_get_random_var_wait(u64, u32) +declare_get_random_var_wait(int, unsigned int) +declare_get_random_var_wait(long, unsigned long) #undef declare_get_random_var -unsigned long randomize_page(unsigned long start, unsigned long range); - /* * This is designed to be standalone for just prandom * users, but for now we include it from <linux/random.h> @@ -122,22 +110,10 @@ unsigned long randomize_page(unsigned long start, unsigned long range); #ifdef CONFIG_ARCH_RANDOM # include <asm/archrandom.h> #else -static inline bool __must_check arch_get_random_long(unsigned long *v) -{ - return false; -} -static inline bool __must_check arch_get_random_int(unsigned int *v) -{ - return false; -} -static inline bool __must_check arch_get_random_seed_long(unsigned long *v) -{ - return false; -} -static inline bool __must_check arch_get_random_seed_int(unsigned int *v) -{ - return false; -} +static inline bool __must_check arch_get_random_long(unsigned long *v) { return false; } +static inline bool __must_check arch_get_random_int(unsigned int *v) { return false; } +static inline bool __must_check arch_get_random_seed_long(unsigned long *v) { return false; } +static inline bool __must_check arch_get_random_seed_int(unsigned int *v) { return false; } #endif /* @@ -161,8 +137,12 @@ static inline bool __init arch_get_random_long_early(unsigned long *v) #endif #ifdef CONFIG_SMP -extern int random_prepare_cpu(unsigned int cpu); -extern int random_online_cpu(unsigned int cpu); +int random_prepare_cpu(unsigned int cpu); +int random_online_cpu(unsigned int cpu); +#endif + +#ifndef MODULE +extern const struct file_operations random_fops, urandom_fops; #endif #endif /* _LINUX_RANDOM_H */ diff --git a/include/linux/siphash.h b/include/linux/siphash.h index cce8a9acc76c..3af1428da559 100644 --- a/include/linux/siphash.h +++ b/include/linux/siphash.h @@ -138,4 +138,32 @@ static inline u32 hsiphash(const void *data, size_t len, return ___hsiphash_aligned(data, len, key); } +/* + * These macros expose the raw SipHash and HalfSipHash permutations. + * Do not use them directly! If you think you have a use for them, + * be sure to CC the maintainer of this file explaining why. + */ + +#define SIPHASH_PERMUTATION(a, b, c, d) ( \ + (a) += (b), (b) = rol64((b), 13), (b) ^= (a), (a) = rol64((a), 32), \ + (c) += (d), (d) = rol64((d), 16), (d) ^= (c), \ + (a) += (d), (d) = rol64((d), 21), (d) ^= (a), \ + (c) += (b), (b) = rol64((b), 17), (b) ^= (c), (c) = rol64((c), 32)) + +#define SIPHASH_CONST_0 0x736f6d6570736575ULL +#define SIPHASH_CONST_1 0x646f72616e646f6dULL +#define SIPHASH_CONST_2 0x6c7967656e657261ULL +#define SIPHASH_CONST_3 0x7465646279746573ULL + +#define HSIPHASH_PERMUTATION(a, b, c, d) ( \ + (a) += (b), (b) = rol32((b), 5), (b) ^= (a), (a) = rol32((a), 16), \ + (c) += (d), (d) = rol32((d), 8), (d) ^= (c), \ + (a) += (d), (d) = rol32((d), 7), (d) ^= (a), \ + (c) += (b), (b) = rol32((b), 13), (b) ^= (c), (c) = rol32((c), 16)) + +#define HSIPHASH_CONST_0 0U +#define HSIPHASH_CONST_1 0U +#define HSIPHASH_CONST_2 0x6c796765U +#define HSIPHASH_CONST_3 0x74656462U + #endif /* _LINUX_SIPHASH_H */ diff --git a/include/linux/timex.h b/include/linux/timex.h index 5745c90c8800..3871b06bd302 100644 --- a/include/linux/timex.h +++ b/include/linux/timex.h @@ -62,6 +62,8 @@ #include <linux/types.h> #include <linux/param.h> +unsigned long random_get_entropy_fallback(void); + #include <asm/timex.h> #ifndef random_get_entropy @@ -74,8 +76,14 @@ * * By default we use get_cycles() for this purpose, but individual * architectures may override this in their asm/timex.h header file. + * If a given arch does not have get_cycles(), then we fallback to + * using random_get_entropy_fallback(). */ +#ifdef get_cycles #define random_get_entropy() ((unsigned long)get_cycles()) +#else +#define random_get_entropy() random_get_entropy_fallback() +#endif #endif /* diff --git a/init/main.c b/init/main.c index 98182c3c2c4b..f057c49f1d9d 100644 --- a/init/main.c +++ b/init/main.c @@ -1035,21 +1035,18 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) softirq_init(); timekeeping_init(); kfence_init(); + time_init(); /* * For best initial stack canary entropy, prepare it after: * - setup_arch() for any UEFI RNG entropy and boot cmdline access - * - timekeeping_init() for ktime entropy used in rand_initialize() - * - rand_initialize() to get any arch-specific entropy like RDRAND - * - add_latent_entropy() to get any latent entropy - * - adding command line entropy + * - timekeeping_init() for ktime entropy used in random_init() + * - time_init() for making random_get_entropy() work on some platforms + * - random_init() to initialize the RNG from from early entropy sources */ - rand_initialize(); - add_latent_entropy(); - add_device_randomness(command_line, strlen(command_line)); + random_init(command_line); boot_init_stack_canary(); - time_init(); perf_event_init(); profile_init(); call_function_init(); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 4ab9949772d5..8e4b3c32fcf9 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -17,6 +17,7 @@ #include <linux/clocksource.h> #include <linux/jiffies.h> #include <linux/time.h> +#include <linux/timex.h> #include <linux/tick.h> #include <linux/stop_machine.h> #include <linux/pvclock_gtod.h> @@ -2397,6 +2398,20 @@ static int timekeeping_validate_timex(const struct __kernel_timex *txc) return 0; } +/** + * random_get_entropy_fallback - Returns the raw clock source value, + * used by random.c for platforms with no valid random_get_entropy(). + */ +unsigned long random_get_entropy_fallback(void) +{ + struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono; + struct clocksource *clock = READ_ONCE(tkr->clock); + + if (unlikely(timekeeping_suspended || !clock)) + return 0; + return clock->read(clock); +} +EXPORT_SYMBOL_GPL(random_get_entropy_fallback); /** * do_adjtimex() - Accessor function to NTP __do_adjtimex function diff --git a/kernel/time/timer.c b/kernel/time/timer.c index a0666d948147..717fcb9fb14a 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1833,8 +1833,6 @@ void update_process_times(int user_tick) { struct task_struct *p = current; - PRANDOM_ADD_NOISE(jiffies, user_tick, p, 0); - /* Note: this timer irq context must be accounted for as well. */ account_process_tick(p, user_tick); run_local_timers(); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 55b9acb2f524..a30d5279efda 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1617,8 +1617,7 @@ config WARN_ALL_UNSEEDED_RANDOM so architecture maintainers really need to do what they can to get the CRNG seeded sooner after the system is booted. However, since users cannot do anything actionable to - address this, by default the kernel will issue only a single - warning for the first use of unseeded randomness. + address this, by default this option is disabled. Say Y here if you want to receive warnings for all uses of unseeded randomness. This will be of use primarily for diff --git a/lib/random32.c b/lib/random32.c index 976632003ec6..d5d9029362cb 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -245,25 +245,13 @@ static struct prandom_test2 { { 407983964U, 921U, 728767059U }, }; -static u32 __extract_hwseed(void) -{ - unsigned int val = 0; - - (void)(arch_get_random_seed_int(&val) || - arch_get_random_int(&val)); - - return val; -} - -static void prandom_seed_early(struct rnd_state *state, u32 seed, - bool mix_with_hwseed) +static void prandom_state_selftest_seed(struct rnd_state *state, u32 seed) { #define LCG(x) ((x) * 69069U) /* super-duper LCG */ -#define HWSEED() (mix_with_hwseed ? __extract_hwseed() : 0) - state->s1 = __seed(HWSEED() ^ LCG(seed), 2U); - state->s2 = __seed(HWSEED() ^ LCG(state->s1), 8U); - state->s3 = __seed(HWSEED() ^ LCG(state->s2), 16U); - state->s4 = __seed(HWSEED() ^ LCG(state->s3), 128U); + state->s1 = __seed(LCG(seed), 2U); + state->s2 = __seed(LCG(state->s1), 8U); + state->s3 = __seed(LCG(state->s2), 16U); + state->s4 = __seed(LCG(state->s3), 128U); } static int __init prandom_state_selftest(void) @@ -274,7 +262,7 @@ static int __init prandom_state_selftest(void) for (i = 0; i < ARRAY_SIZE(test1); i++) { struct rnd_state state; - prandom_seed_early(&state, test1[i].seed, false); + prandom_state_selftest_seed(&state, test1[i].seed); prandom_warmup(&state); if (test1[i].result != prandom_u32_state(&state)) @@ -289,7 +277,7 @@ static int __init prandom_state_selftest(void) for (i = 0; i < ARRAY_SIZE(test2); i++) { struct rnd_state state; - prandom_seed_early(&state, test2[i].seed, false); + prandom_state_selftest_seed(&state, test2[i].seed); prandom_warmup(&state); for (j = 0; j < test2[i].iteration - 1; j++) @@ -310,324 +298,3 @@ static int __init prandom_state_selftest(void) } core_initcall(prandom_state_selftest); #endif - -/* - * The prandom_u32() implementation is now completely separate from the - * prandom_state() functions, which are retained (for now) for compatibility. - * - * Because of (ab)use in the networking code for choosing random TCP/UDP port - * numbers, which open DoS possibilities if guessable, we want something - * stronger than a standard PRNG. But the performance requirements of - * the network code do not allow robust crypto for this application. - * - * So this is a homebrew Junior Spaceman implementation, based on the - * lowest-latency trustworthy crypto primitive available, SipHash. - * (The authors of SipHash have not been consulted about this abuse of - * their work.) - * - * Standard SipHash-2-4 uses 2n+4 rounds to hash n words of input to - * one word of output. This abbreviated version uses 2 rounds per word - * of output. - */ - -struct siprand_state { - unsigned long v0; - unsigned long v1; - unsigned long v2; - unsigned long v3; -}; - -static DEFINE_PER_CPU(struct siprand_state, net_rand_state) __latent_entropy; -DEFINE_PER_CPU(unsigned long, net_rand_noise); -EXPORT_PER_CPU_SYMBOL(net_rand_noise); - -/* - * This is the core CPRNG function. As "pseudorandom", this is not used - * for truly valuable things, just intended to be a PITA to guess. - * For maximum speed, we do just two SipHash rounds per word. This is - * the same rate as 4 rounds per 64 bits that SipHash normally uses, - * so hopefully it's reasonably secure. - * - * There are two changes from the official SipHash finalization: - * - We omit some constants XORed with v2 in the SipHash spec as irrelevant; - * they are there only to make the output rounds distinct from the input - * rounds, and this application has no input rounds. - * - Rather than returning v0^v1^v2^v3, return v1+v3. - * If you look at the SipHash round, the last operation on v3 is - * "v3 ^= v0", so "v0 ^ v3" just undoes that, a waste of time. - * Likewise "v1 ^= v2". (The rotate of v2 makes a difference, but - * it still cancels out half of the bits in v2 for no benefit.) - * Second, since the last combining operation was xor, continue the - * pattern of alternating xor/add for a tiny bit of extra non-linearity. - */ -static inline u32 siprand_u32(struct siprand_state *s) -{ - unsigned long v0 = s->v0, v1 = s->v1, v2 = s->v2, v3 = s->v3; - unsigned long n = raw_cpu_read(net_rand_noise); - - v3 ^= n; - PRND_SIPROUND(v0, v1, v2, v3); - PRND_SIPROUND(v0, v1, v2, v3); - v0 ^= n; - s->v0 = v0; s->v1 = v1; s->v2 = v2; s->v3 = v3; - return v1 + v3; -} - - -/** - * prandom_u32 - pseudo random number generator - * - * A 32 bit pseudo-random number is generated using a fast - * algorithm suitable for simulation. This algorithm is NOT - * considered safe for cryptographic use. - */ -u32 prandom_u32(void) -{ - struct siprand_state *state = get_cpu_ptr(&net_rand_state); - u32 res = siprand_u32(state); - - put_cpu_ptr(&net_rand_state); - return res; -} -EXPORT_SYMBOL(prandom_u32); - -/** - * prandom_bytes - get the requested number of pseudo-random bytes - * @buf: where to copy the pseudo-random bytes to - * @bytes: the requested number of bytes - */ -void prandom_bytes(void *buf, size_t bytes) -{ - struct siprand_state *state = get_cpu_ptr(&net_rand_state); - u8 *ptr = buf; - - while (bytes >= sizeof(u32)) { - put_unaligned(siprand_u32(state), (u32 *)ptr); - ptr += sizeof(u32); - bytes -= sizeof(u32); - } - - if (bytes > 0) { - u32 rem = siprand_u32(state); - - do { - *ptr++ = (u8)rem; - rem >>= BITS_PER_BYTE; - } while (--bytes > 0); - } - put_cpu_ptr(&net_rand_state); -} -EXPORT_SYMBOL(prandom_bytes); - -/** - * prandom_seed - add entropy to pseudo random number generator - * @entropy: entropy value - * - * Add some additional seed material to the prandom pool. - * The "entropy" is actually our IP address (the only caller is - * the network code), not for unpredictability, but to ensure that - * different machines are initialized differently. - */ -void prandom_seed(u32 entropy) -{ - int i; - - add_device_randomness(&entropy, sizeof(entropy)); - - for_each_possible_cpu(i) { - struct siprand_state *state = per_cpu_ptr(&net_rand_state, i); - unsigned long v0 = state->v0, v1 = state->v1; - unsigned long v2 = state->v2, v3 = state->v3; - - do { - v3 ^= entropy; - PRND_SIPROUND(v0, v1, v2, v3); - PRND_SIPROUND(v0, v1, v2, v3); - v0 ^= entropy; - } while (unlikely(!v0 || !v1 || !v2 || !v3)); - - WRITE_ONCE(state->v0, v0); - WRITE_ONCE(state->v1, v1); - WRITE_ONCE(state->v2, v2); - WRITE_ONCE(state->v3, v3); - } -} -EXPORT_SYMBOL(prandom_seed); - -/* - * Generate some initially weak seeding values to allow - * the prandom_u32() engine to be started. - */ -static int __init prandom_init_early(void) -{ - int i; - unsigned long v0, v1, v2, v3; - - if (!arch_get_random_long(&v0)) - v0 = jiffies; - if (!arch_get_random_long(&v1)) - v1 = random_get_entropy(); - v2 = v0 ^ PRND_K0; - v3 = v1 ^ PRND_K1; - - for_each_possible_cpu(i) { - struct siprand_state *state; - - v3 ^= i; - PRND_SIPROUND(v0, v1, v2, v3); - PRND_SIPROUND(v0, v1, v2, v3); - v0 ^= i; - - state = per_cpu_ptr(&net_rand_state, i); - state->v0 = v0; state->v1 = v1; - state->v2 = v2; state->v3 = v3; - } - - return 0; -} -core_initcall(prandom_init_early); - - -/* Stronger reseeding when available, and periodically thereafter. */ -static void prandom_reseed(struct timer_list *unused); - -static DEFINE_TIMER(seed_timer, prandom_reseed); - -static void prandom_reseed(struct timer_list *unused) -{ - unsigned long expires; - int i; - - /* - * Reinitialize each CPU's PRNG with 128 bits of key. - * No locking on the CPUs, but then somewhat random results are, - * well, expected. - */ - for_each_possible_cpu(i) { - struct siprand_state *state; - unsigned long v0 = get_random_long(), v2 = v0 ^ PRND_K0; - unsigned long v1 = get_random_long(), v3 = v1 ^ PRND_K1; -#if BITS_PER_LONG == 32 - int j; - - /* - * On 32-bit machines, hash in two extra words to - * approximate 128-bit key length. Not that the hash - * has that much security, but this prevents a trivial - * 64-bit brute force. - */ - for (j = 0; j < 2; j++) { - unsigned long m = get_random_long(); - - v3 ^= m; - PRND_SIPROUND(v0, v1, v2, v3); - PRND_SIPROUND(v0, v1, v2, v3); - v0 ^= m; - } -#endif - /* - * Probably impossible in practice, but there is a - * theoretical risk that a race between this reseeding - * and the target CPU writing its state back could - * create the all-zero SipHash fixed point. - * - * To ensure that never happens, ensure the state - * we write contains no zero words. - */ - state = per_cpu_ptr(&net_rand_state, i); - WRITE_ONCE(state->v0, v0 ? v0 : -1ul); - WRITE_ONCE(state->v1, v1 ? v1 : -1ul); - WRITE_ONCE(state->v2, v2 ? v2 : -1ul); - WRITE_ONCE(state->v3, v3 ? v3 : -1ul); - } - - /* reseed every ~60 seconds, in [40 .. 80) interval with slack */ - expires = round_jiffies(jiffies + 40 * HZ + prandom_u32_max(40 * HZ)); - mod_timer(&seed_timer, expires); -} - -/* - * The random ready callback can be called from almost any interrupt. - * To avoid worrying about whether it's safe to delay that interrupt - * long enough to seed all CPUs, just schedule an immediate timer event. - */ -static int prandom_timer_start(struct notifier_block *nb, - unsigned long action, void *data) -{ - mod_timer(&seed_timer, jiffies); - return 0; -} - -#ifdef CONFIG_RANDOM32_SELFTEST -/* Principle: True 32-bit random numbers will all have 16 differing bits on - * average. For each 32-bit number, there are 601M numbers differing by 16 - * bits, and 89% of the numbers differ by at least 12 bits. Note that more - * than 16 differing bits also implies a correlation with inverted bits. Thus - * we take 1024 random numbers and compare each of them to the other ones, - * counting the deviation of correlated bits to 16. Constants report 32, - * counters 32-log2(TEST_SIZE), and pure randoms, around 6 or lower. With the - * u32 total, TEST_SIZE may be as large as 4096 samples. - */ -#define TEST_SIZE 1024 -static int __init prandom32_state_selftest(void) -{ - unsigned int x, y, bits, samples; - u32 xor, flip; - u32 total; - u32 *data; - - data = kmalloc(sizeof(*data) * TEST_SIZE, GFP_KERNEL); - if (!data) - return 0; - - for (samples = 0; samples < TEST_SIZE; samples++) - data[samples] = prandom_u32(); - - flip = total = 0; - for (x = 0; x < samples; x++) { - for (y = 0; y < samples; y++) { - if (x == y) - continue; - xor = data[x] ^ data[y]; - flip |= xor; - bits = hweight32(xor); - total += (bits - 16) * (bits - 16); - } - } - - /* We'll return the average deviation as 2*sqrt(corr/samples), which - * is also sqrt(4*corr/samples) which provides a better resolution. - */ - bits = int_sqrt(total / (samples * (samples - 1)) * 4); - if (bits > 6) - pr_warn("prandom32: self test failed (at least %u bits" - " correlated, fixed_mask=%#x fixed_value=%#x\n", - bits, ~flip, data[0] & ~flip); - else - pr_info("prandom32: self test passed (less than %u bits" - " correlated)\n", - bits+1); - kfree(data); - return 0; -} -core_initcall(prandom32_state_selftest); -#endif /* CONFIG_RANDOM32_SELFTEST */ - -/* - * Start periodic full reseeding as soon as strong - * random numbers are available. - */ -static int __init prandom_init_late(void) -{ - static struct notifier_block random_ready = { - .notifier_call = prandom_timer_start - }; - int ret = register_random_ready_notifier(&random_ready); - - if (ret == -EALREADY) { - prandom_timer_start(&random_ready, 0, NULL); - ret = 0; - } - return ret; -} -late_initcall(prandom_init_late); diff --git a/lib/siphash.c b/lib/siphash.c index 72b9068ab57b..71d315a6ad62 100644 --- a/lib/siphash.c +++ b/lib/siphash.c @@ -18,19 +18,13 @@ #include <asm/word-at-a-time.h> #endif -#define SIPROUND \ - do { \ - v0 += v1; v1 = rol64(v1, 13); v1 ^= v0; v0 = rol64(v0, 32); \ - v2 += v3; v3 = rol64(v3, 16); v3 ^= v2; \ - v0 += v3; v3 = rol64(v3, 21); v3 ^= v0; \ - v2 += v1; v1 = rol64(v1, 17); v1 ^= v2; v2 = rol64(v2, 32); \ - } while (0) +#define SIPROUND SIPHASH_PERMUTATION(v0, v1, v2, v3) #define PREAMBLE(len) \ - u64 v0 = 0x736f6d6570736575ULL; \ - u64 v1 = 0x646f72616e646f6dULL; \ - u64 v2 = 0x6c7967656e657261ULL; \ - u64 v3 = 0x7465646279746573ULL; \ + u64 v0 = SIPHASH_CONST_0; \ + u64 v1 = SIPHASH_CONST_1; \ + u64 v2 = SIPHASH_CONST_2; \ + u64 v3 = SIPHASH_CONST_3; \ u64 b = ((u64)(len)) << 56; \ v3 ^= key->key[1]; \ v2 ^= key->key[0]; \ @@ -389,19 +383,13 @@ u32 hsiphash_4u32(const u32 first, const u32 second, const u32 third, } EXPORT_SYMBOL(hsiphash_4u32); #else -#define HSIPROUND \ - do { \ - v0 += v1; v1 = rol32(v1, 5); v1 ^= v0; v0 = rol32(v0, 16); \ - v2 += v3; v3 = rol32(v3, 8); v3 ^= v2; \ - v0 += v3; v3 = rol32(v3, 7); v3 ^= v0; \ - v2 += v1; v1 = rol32(v1, 13); v1 ^= v2; v2 = rol32(v2, 16); \ - } while (0) +#define HSIPROUND HSIPHASH_PERMUTATION(v0, v1, v2, v3) #define HPREAMBLE(len) \ - u32 v0 = 0; \ - u32 v1 = 0; \ - u32 v2 = 0x6c796765U; \ - u32 v3 = 0x74656462U; \ + u32 v0 = HSIPHASH_CONST_0; \ + u32 v1 = HSIPHASH_CONST_1; \ + u32 v2 = HSIPHASH_CONST_2; \ + u32 v3 = HSIPHASH_CONST_3; \ u32 b = ((u32)(len)) << 24; \ v3 ^= key->key[1]; \ v2 ^= key->key[0]; \ diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 40d26a07a133..fb77f7bfd126 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -750,61 +750,38 @@ static int __init debug_boot_weak_hash_enable(char *str) } early_param("debug_boot_weak_hash", debug_boot_weak_hash_enable); -static DEFINE_STATIC_KEY_TRUE(not_filled_random_ptr_key); -static siphash_key_t ptr_key __read_mostly; +static DEFINE_STATIC_KEY_FALSE(filled_random_ptr_key); static void enable_ptr_key_workfn(struct work_struct *work) { - get_random_bytes(&ptr_key, sizeof(ptr_key)); - /* Needs to run from preemptible context */ - static_branch_disable(¬_filled_random_ptr_key); + static_branch_enable(&filled_random_ptr_key); } -static DECLARE_WORK(enable_ptr_key_work, enable_ptr_key_workfn); - -static int fill_random_ptr_key(struct notifier_block *nb, - unsigned long action, void *data) -{ - /* This may be in an interrupt handler. */ - queue_work(system_unbound_wq, &enable_ptr_key_work); - return 0; -} - -static struct notifier_block random_ready = { - .notifier_call = fill_random_ptr_key -}; - -static int __init initialize_ptr_random(void) -{ - int key_size = sizeof(ptr_key); - int ret; - - /* Use hw RNG if available. */ - if (get_random_bytes_arch(&ptr_key, key_size) == key_size) { - static_branch_disable(¬_filled_random_ptr_key); - return 0; - } - - ret = register_random_ready_notifier(&random_ready); - if (!ret) { - return 0; - } else if (ret == -EALREADY) { - /* This is in preemptible context */ - enable_ptr_key_workfn(&enable_ptr_key_work); - return 0; - } - - return ret; -} -early_initcall(initialize_ptr_random); - /* Maps a pointer to a 32 bit unique identifier. */ static inline int __ptr_to_hashval(const void *ptr, unsigned long *hashval_out) { + static siphash_key_t ptr_key __read_mostly; unsigned long hashval; - if (static_branch_unlikely(¬_filled_random_ptr_key)) - return -EAGAIN; + if (!static_branch_likely(&filled_random_ptr_key)) { + static bool filled = false; + static DEFINE_SPINLOCK(filling); + static DECLARE_WORK(enable_ptr_key_work, enable_ptr_key_workfn); + unsigned long flags; + + if (!system_unbound_wq || + (!rng_is_initialized() && !rng_has_arch_random()) || + !spin_trylock_irqsave(&filling, flags)) + return -EAGAIN; + + if (!filled) { + get_random_bytes(&ptr_key, sizeof(ptr_key)); + queue_work(system_unbound_wq, &enable_ptr_key_work); + filled = true; + } + spin_unlock_irqrestore(&filling, flags); + } + #ifdef CONFIG_64BIT hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key); diff --git a/mm/util.c b/mm/util.c index 3492a9e81aa3..ac63e5ca8b21 100644 --- a/mm/util.c +++ b/mm/util.c @@ -343,6 +343,38 @@ unsigned long randomize_stack_top(unsigned long stack_top) #endif } +/** + * randomize_page - Generate a random, page aligned address + * @start: The smallest acceptable address the caller will take. + * @range: The size of the area, starting at @start, within which the + * random address must fall. + * + * If @start + @range would overflow, @range is capped. + * + * NOTE: Historical use of randomize_range, which this replaces, presumed that + * @start was already page aligned. We now align it regardless. + * + * Return: A page aligned address within [start, start + range). On error, + * @start is returned. + */ +unsigned long randomize_page(unsigned long start, unsigned long range) +{ + if (!PAGE_ALIGNED(start)) { + range -= PAGE_ALIGN(start) - start; + start = PAGE_ALIGN(start); + } + + if (start > ULONG_MAX - range) + range = ULONG_MAX - start; + + range >>= PAGE_SHIFT; + + if (range == 0) + return start; + + return start + (get_random_long() % range << PAGE_SHIFT); +} + #ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT unsigned long arch_randomize_brk(struct mm_struct *mm) { diff --git a/net/core/dev.c b/net/core/dev.c index 2771fd22dc6a..191ec76d4c3b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3527,7 +3527,6 @@ static int xmit_one(struct sk_buff *skb, struct net_device *dev, dev_queue_xmit_nit(skb, dev); len = skb->len; - PRANDOM_ADD_NOISE(skb, dev, txq, len + jiffies); trace_net_dev_start_xmit(skb, dev); rc = netdev_start_xmit(skb, dev, txq, more); trace_net_dev_xmit(skb, rc, dev, len); @@ -4168,7 +4167,6 @@ static int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) if (!skb) goto out; - PRANDOM_ADD_NOISE(skb, dev, txq, jiffies); HARD_TX_LOCK(dev, txq, cpu); if (!netif_xmit_stopped(txq)) { @@ -4234,7 +4232,6 @@ int __dev_direct_xmit(struct sk_buff *skb, u16 queue_id) skb_set_queue_mapping(skb, queue_id); txq = skb_get_tx_queue(dev, skb); - PRANDOM_ADD_NOISE(skb, dev, txq, jiffies); local_bh_disable(); diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index 53a6b14dc50a..3d6d33ac20cc 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -536,10 +536,8 @@ static int __inet_insert_ifa(struct in_ifaddr *ifa, struct nlmsghdr *nlh, return ret; } - if (!(ifa->ifa_flags & IFA_F_SECONDARY)) { - prandom_seed((__force u32) ifa->ifa_local); + if (!(ifa->ifa_flags & IFA_F_SECONDARY)) ifap = last_primary; - } rcu_assign_pointer(ifa->ifa_next, *ifap); rcu_assign_pointer(*ifap, ifa); diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index b22504176588..e7c68fa12fae 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -3972,8 +3972,6 @@ static void addrconf_dad_begin(struct inet6_ifaddr *ifp) addrconf_join_solict(dev, &ifp->addr); - prandom_seed((__force u32) ifp->addr.s6_addr32[3]); - read_lock_bh(&idev->lock); spin_lock(&ifp->lock); if (ifp->state == INET6_IFADDR_STATE_DEAD) |