diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2016-12-07 01:15:44 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-12-07 13:16:04 -0500 |
| commit | ef0915cacd04c9e35be5f9d62a4e4b5b4b9bcfd1 (patch) | |
| tree | b3589bba5b7632cc8e763ce614bc5af35d58bc36 | |
| parent | 90364feaf70f251533feff3f228f82df9a9f52b6 (diff) | |
| download | linux-ef0915cacd04c9e35be5f9d62a4e4b5b4b9bcfd1.tar.bz2 | |
bpf: fix loading of BPF_MAXINSNS sized programs
General assumption is that single program can hold up to BPF_MAXINSNS,
that is, 4096 number of instructions. It is the case with cBPF and
that limit was carried over to eBPF. When recently testing digest, I
noticed that it's actually not possible to feed 4096 instructions
via bpf(2).
The check for > BPF_MAXINSNS was added back then to bpf_check() in
cbd357008604 ("bpf: verifier (add ability to receive verification log)").
However, 09756af46893 ("bpf: expand BPF syscall with program load/unload")
added yet another check that comes before that into bpf_prog_load(),
but this time bails out already in case of >= BPF_MAXINSNS.
Fix it up and perform the check early in bpf_prog_load(), so we can drop
the second one in bpf_check(). It makes sense, because also a 0 insn
program is useless and we don't want to waste any resources doing work
up to bpf_check() point. The existing bpf(2) man page documents E2BIG
as the official error for such cases, so just stick with it as well.
Fixes: 09756af46893 ("bpf: expand BPF syscall with program load/unload")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | kernel/bpf/syscall.c | 4 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 3 |
2 files changed, 2 insertions, 5 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index c0d2b423ce93..88f609f1c0c3 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -786,8 +786,8 @@ static int bpf_prog_load(union bpf_attr *attr) /* eBPF programs must be GPL compatible to use GPL-ed functions */ is_gpl = license_is_gpl_compatible(license); - if (attr->insn_cnt >= BPF_MAXINSNS) - return -EINVAL; + if (attr->insn_cnt == 0 || attr->insn_cnt > BPF_MAXINSNS) + return -E2BIG; if (type == BPF_PROG_TYPE_KPROBE && attr->kern_version != LINUX_VERSION_CODE) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index cb37339ca0da..da9fb2a9b7eb 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3133,9 +3133,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) struct bpf_verifier_env *env; int ret = -EINVAL; - if ((*prog)->len <= 0 || (*prog)->len > BPF_MAXINSNS) - return -E2BIG; - /* 'struct bpf_verifier_env' can be global, but since it's not small, * allocate/free it every time bpf_check() is called */ |