diff options
| -rw-r--r-- | arch/s390/net/bpf_jit_comp.c | 45 | ||||
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 50 | ||||
| -rw-r--r-- | include/linux/filter.h | 13 | ||||
| -rw-r--r-- | kernel/bpf/core.c | 39 |
4 files changed, 72 insertions, 75 deletions
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index f2833c5b218a..b734f975c22e 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -5,11 +5,9 @@ * * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> */ -#include <linux/moduleloader.h> #include <linux/netdevice.h> #include <linux/if_vlan.h> #include <linux/filter.h> -#include <linux/random.h> #include <linux/init.h> #include <asm/cacheflush.h> #include <asm/facility.h> @@ -148,6 +146,12 @@ struct bpf_jit { ret; \ }) +static void bpf_jit_fill_hole(void *area, unsigned int size) +{ + /* Fill whole space with illegal instructions */ + memset(area, 0, size); +} + static void bpf_jit_prologue(struct bpf_jit *jit) { /* Save registers and create stack frame if necessary */ @@ -780,38 +784,6 @@ out: return -1; } -/* - * Note: for security reasons, bpf code will follow a randomly - * sized amount of illegal instructions. - */ -struct bpf_binary_header { - unsigned int pages; - u8 image[]; -}; - -static struct bpf_binary_header *bpf_alloc_binary(unsigned int bpfsize, - u8 **image_ptr) -{ - struct bpf_binary_header *header; - unsigned int sz, hole; - - /* Most BPF filters are really small, but if some of them fill a page, - * allow at least 128 extra bytes for illegal instructions. - */ - sz = round_up(bpfsize + sizeof(*header) + 128, PAGE_SIZE); - header = module_alloc(sz); - if (!header) - return NULL; - memset(header, 0, sz); - header->pages = sz / PAGE_SIZE; - hole = min(sz - (bpfsize + sizeof(*header)), PAGE_SIZE - sizeof(*header)); - /* Insert random number of illegal instructions before BPF code - * and make sure the first instruction starts at an even address. - */ - *image_ptr = &header->image[(prandom_u32() % hole) & -2]; - return header; -} - void bpf_jit_compile(struct bpf_prog *fp) { struct bpf_binary_header *header = NULL; @@ -850,7 +822,8 @@ void bpf_jit_compile(struct bpf_prog *fp) size = prg_len + lit_len; if (size >= BPF_SIZE_MAX) goto out; - header = bpf_alloc_binary(size, &jit.start); + header = bpf_jit_binary_alloc(size, &jit.start, + 2, bpf_jit_fill_hole); if (!header) goto out; jit.prg = jit.mid = jit.start + prg_len; @@ -884,7 +857,7 @@ 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); 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); diff --git a/include/linux/filter.h b/include/linux/filter.h index 8f82ef3f1cdd..868764fcffb8 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -289,6 +289,11 @@ struct sock_fprog_kern { struct sock_filter *filter; }; +struct bpf_binary_header { + unsigned int pages; + u8 image[]; +}; + struct bpf_work_struct { struct bpf_prog *prog; struct work_struct work; @@ -358,6 +363,14 @@ struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size, gfp_t gfp_extra_flags); void __bpf_prog_free(struct bpf_prog *fp); +typedef void (*bpf_jit_fill_hole_t)(void *area, unsigned int size); + +struct bpf_binary_header * +bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, + unsigned int alignment, + bpf_jit_fill_hole_t bpf_fill_ill_insns); +void bpf_jit_binary_free(struct bpf_binary_header *hdr); + static inline void bpf_prog_unlock_free(struct bpf_prog *fp) { bpf_prog_unlock_ro(fp); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 2c2bfaacce66..8ee520f0ec70 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -20,9 +20,12 @@ * Andi Kleen - Fix a few bad bugs and races. * Kris Katterjohn - Added many additional checks in bpf_check_classic() */ + #include <linux/filter.h> #include <linux/skbuff.h> #include <linux/vmalloc.h> +#include <linux/random.h> +#include <linux/moduleloader.h> #include <asm/unaligned.h> /* Registers */ @@ -125,6 +128,42 @@ void __bpf_prog_free(struct bpf_prog *fp) } EXPORT_SYMBOL_GPL(__bpf_prog_free); +struct bpf_binary_header * +bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, + unsigned int alignment, + bpf_jit_fill_hole_t bpf_fill_ill_insns) +{ + struct bpf_binary_header *hdr; + unsigned int size, hole, start; + + /* 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 illegal instructions. + */ + size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE); + hdr = module_alloc(size); + if (hdr == NULL) + return NULL; + + /* Fill space with illegal/arch-dep instructions. */ + bpf_fill_ill_insns(hdr, size); + + hdr->pages = size / PAGE_SIZE; + hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)), + PAGE_SIZE - sizeof(*hdr)); + start = (prandom_u32() % hole) & ~(alignment - 1); + + /* Leave a random number of instructions before BPF code. */ + *image_ptr = &hdr->image[start]; + + return hdr; +} + +void bpf_jit_binary_free(struct bpf_binary_header *hdr) +{ + module_free(NULL, hdr); +} + /* Base function for offset calculation. Needs to go into .text section, * therefore keeping it non-static as well; will also be used by JITs * anyway later on, so do not let the compiler omit it. |