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authorLinus Torvalds <torvalds@linux-foundation.org>2018-08-15 21:16:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-15 21:16:02 -0700
commit99a2c789ddeb703cf7b0a3d889ab1a25cf4cbbaf (patch)
tree3a653ba4bfb2db0c8fc52fbb5a2f0dc2e817e513 /lib
parentfa3b39cdafbfd5d9b1d064f5cf63cf0314f1d070 (diff)
parent9a47249d444d344051c7c0e909fad0e88515a5c2 (diff)
Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random
Pull random updates from Ted Ts'o: "Some changes to trust cpu-based hwrng (such as RDRAND) for initializing hashed pointers and (optionally, controlled by a config option) to initialize the CRNG to avoid boot hangs" * tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random: random: Make crng state queryable random: remove preempt disabled region random: add a config option to trust the CPU's hwrng vsprintf: Add command line option debug_boot_weak_hash vsprintf: Use hw RNG for ptr_key random: Return nbytes filled from hw RNG random: Fix whitespace pre random-bytes work
Diffstat (limited to 'lib')
-rw-r--r--lib/vsprintf.c27
1 files changed, 26 insertions, 1 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index cda186230287..d5b3a3f95c01 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1651,6 +1651,17 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
return widen_string(buf, buf - buf_start, end, spec);
}
+/* Make pointers available for printing early in the boot sequence. */
+static int debug_boot_weak_hash __ro_after_init;
+
+static int __init debug_boot_weak_hash_enable(char *str)
+{
+ debug_boot_weak_hash = 1;
+ pr_info("debug_boot_weak_hash enabled\n");
+ return 0;
+}
+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;
@@ -1675,8 +1686,16 @@ static struct random_ready_callback random_ready = {
static int __init initialize_ptr_random(void)
{
- int ret = add_random_ready_callback(&random_ready);
+ 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(&not_filled_random_ptr_key);
+ return 0;
+ }
+
+ ret = add_random_ready_callback(&random_ready);
if (!ret) {
return 0;
} else if (ret == -EALREADY) {
@@ -1695,6 +1714,12 @@ static char *ptr_to_id(char *buf, char *end, void *ptr, struct printf_spec spec)
const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)";
unsigned long hashval;
+ /* When debugging early boot use non-cryptographically secure hash. */
+ if (unlikely(debug_boot_weak_hash)) {
+ hashval = hash_long((unsigned long)ptr, 32);
+ return pointer_string(buf, end, (const void *)hashval, spec);
+ }
+
if (static_branch_unlikely(&not_filled_random_ptr_key)) {
spec.field_width = 2 * sizeof(ptr);
/* string length must be less than default_width */