From aafe6ae9cee32df85eb5e8bb6dd1d918e6807b09 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Sun, 18 Dec 2016 01:52:57 +0100 Subject: bpf: dynamically allocate digest scratch buffer Geert rightfully complained that 7bd509e311f4 ("bpf: add prog_digest and expose it via fdinfo/netlink") added a too large allocation of variable 'raw' from bss section, and should instead be done dynamically: # ./scripts/bloat-o-meter kernel/bpf/core.o.1 kernel/bpf/core.o.2 add/remove: 3/0 grow/shrink: 0/0 up/down: 33291/0 (33291) function old new delta raw - 32832 +32832 [...] Since this is only relevant during program creation path, which can be considered slow-path anyway, lets allocate that dynamically and be not implicitly dependent on verifier mutex. Move bpf_prog_calc_digest() at the beginning of replace_map_fd_with_map_ptr() and also error handling stays straight forward. Reported-by: Geert Uytterhoeven Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- kernel/bpf/core.c | 27 ++++++++++++++++----------- kernel/bpf/syscall.c | 2 +- kernel/bpf/verifier.c | 6 ++++-- 3 files changed, 21 insertions(+), 14 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 83e0d153b0b4..75c08b8068d6 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -136,28 +136,29 @@ void __bpf_prog_free(struct bpf_prog *fp) vfree(fp); } -#define SHA_BPF_RAW_SIZE \ - round_up(MAX_BPF_SIZE + sizeof(__be64) + 1, SHA_MESSAGE_BYTES) - -/* Called under verifier mutex. */ -void bpf_prog_calc_digest(struct bpf_prog *fp) +int bpf_prog_calc_digest(struct bpf_prog *fp) { const u32 bits_offset = SHA_MESSAGE_BYTES - sizeof(__be64); - static u32 ws[SHA_WORKSPACE_WORDS]; - static u8 raw[SHA_BPF_RAW_SIZE]; - struct bpf_insn *dst = (void *)raw; + u32 raw_size = bpf_prog_digest_scratch_size(fp); + u32 ws[SHA_WORKSPACE_WORDS]; u32 i, bsize, psize, blocks; + struct bpf_insn *dst; bool was_ld_map; - u8 *todo = raw; + u8 *raw, *todo; __be32 *result; __be64 *bits; + raw = vmalloc(raw_size); + if (!raw) + return -ENOMEM; + sha_init(fp->digest); memset(ws, 0, sizeof(ws)); /* We need to take out the map fd for the digest calculation * since they are unstable from user space side. */ + dst = (void *)raw; for (i = 0, was_ld_map = false; i < fp->len; i++) { dst[i] = fp->insnsi[i]; if (!was_ld_map && @@ -177,12 +178,13 @@ void bpf_prog_calc_digest(struct bpf_prog *fp) } } - psize = fp->len * sizeof(struct bpf_insn); - memset(&raw[psize], 0, sizeof(raw) - psize); + psize = bpf_prog_insn_size(fp); + memset(&raw[psize], 0, raw_size - psize); raw[psize++] = 0x80; bsize = round_up(psize, SHA_MESSAGE_BYTES); blocks = bsize / SHA_MESSAGE_BYTES; + todo = raw; if (bsize - psize >= sizeof(__be64)) { bits = (__be64 *)(todo + bsize - sizeof(__be64)); } else { @@ -199,6 +201,9 @@ void bpf_prog_calc_digest(struct bpf_prog *fp) result = (__force __be32 *)fp->digest; for (i = 0; i < SHA_DIGEST_WORDS; i++) result[i] = cpu_to_be32(fp->digest[i]); + + vfree(raw); + return 0; } static bool bpf_is_jmp_and_has_target(const struct bpf_insn *insn) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 4819ec9d95f6..35d674c1f12e 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -811,7 +811,7 @@ static int bpf_prog_load(union bpf_attr *attr) err = -EFAULT; if (copy_from_user(prog->insns, u64_to_user_ptr(attr->insns), - prog->len * sizeof(struct bpf_insn)) != 0) + bpf_prog_insn_size(prog)) != 0) goto free_prog; prog->orig_prog = NULL; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 81e267bc4640..64b7b1abe087 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2931,6 +2931,10 @@ static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) int insn_cnt = env->prog->len; int i, j, err; + err = bpf_prog_calc_digest(env->prog); + if (err) + return err; + for (i = 0; i < insn_cnt; i++, insn++) { if (BPF_CLASS(insn->code) == BPF_LDX && (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { @@ -3178,8 +3182,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) log_level = 0; } - bpf_prog_calc_digest(env->prog); - ret = replace_map_fd_with_map_ptr(env); if (ret < 0) goto skip_full_check; -- cgit v1.2.3