diff options
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/core.c | 39 |
1 files changed, 39 insertions, 0 deletions
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. |