diff options
Diffstat (limited to 'arch/x86')
-rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 50 |
1 files changed, 11 insertions, 39 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 06f8c17f5484..9de0b5476b0c 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -8,12 +8,10 @@ * as published by the Free Software Foundation; version 2 * of the License. */ -#include <linux/moduleloader.h> -#include <asm/cacheflush.h> #include <linux/netdevice.h> #include <linux/filter.h> #include <linux/if_vlan.h> -#include <linux/random.h> +#include <asm/cacheflush.h> int bpf_jit_enable __read_mostly; @@ -109,39 +107,6 @@ static inline void bpf_flush_icache(void *start, void *end) #define CHOOSE_LOAD_FUNC(K, func) \ ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset) -struct bpf_binary_header { - unsigned int pages; - /* Note : for security reasons, bpf code will follow a randomly - * sized amount of int3 instructions - */ - u8 image[]; -}; - -static struct bpf_binary_header *bpf_alloc_binary(unsigned int proglen, - u8 **image_ptr) -{ - unsigned int sz, hole; - struct bpf_binary_header *header; - - /* Most of BPF filters are really small, - * but if some of them fill a page, allow at least - * 128 extra bytes to insert a random section of int3 - */ - sz = round_up(proglen + sizeof(*header) + 128, PAGE_SIZE); - header = module_alloc(sz); - if (!header) - return NULL; - - memset(header, 0xcc, sz); /* fill whole space with int3 instructions */ - - header->pages = sz / PAGE_SIZE; - hole = min(sz - (proglen + sizeof(*header)), PAGE_SIZE - sizeof(*header)); - - /* insert a random number of int3 instructions before BPF code */ - *image_ptr = &header->image[prandom_u32() % hole]; - return header; -} - /* pick a register outside of BPF range for JIT internal work */ #define AUX_REG (MAX_BPF_REG + 1) @@ -206,6 +171,12 @@ static inline u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg) return byte + reg2hex[dst_reg] + (reg2hex[src_reg] << 3); } +static void jit_fill_hole(void *area, unsigned int size) +{ + /* fill whole space with int3 instructions */ + memset(area, 0xcc, size); +} + struct jit_context { unsigned int cleanup_addr; /* epilogue code offset */ bool seen_ld_abs; @@ -959,7 +930,7 @@ void bpf_int_jit_compile(struct bpf_prog *prog) if (proglen <= 0) { image = NULL; if (header) - module_free(NULL, header); + bpf_jit_binary_free(header); goto out; } if (image) { @@ -969,7 +940,8 @@ void bpf_int_jit_compile(struct bpf_prog *prog) break; } if (proglen == oldproglen) { - header = bpf_alloc_binary(proglen, &image); + header = bpf_jit_binary_alloc(proglen, &image, + 1, jit_fill_hole); if (!header) goto out; } @@ -998,7 +970,7 @@ void bpf_jit_free(struct bpf_prog *fp) goto free_filter; set_memory_rw(addr, header->pages); - module_free(NULL, header); + bpf_jit_binary_free(header); free_filter: bpf_prog_unlock_free(fp); |