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| author | Daniel Borkmann <daniel@iogearbox.net> | 2017-06-06 18:38:04 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-06-06 16:39:48 -0400 |
| commit | 92046578ac88e0a93f8ef03240e6c832b0189aa7 (patch) | |
| tree | 3706fad432d13a5174698b4a0fd3e9d5446c5daf /kernel | |
| parent | feec084a7cf49adb4a87bea9867fb2ba99821f48 (diff) | |
| download | linux-92046578ac88e0a93f8ef03240e6c832b0189aa7.tar.bz2 | |
bpf: cgroup skb progs cannot access ld_abs/ind
Commit fb9a307d11d6 ("bpf: Allow CGROUP_SKB eBPF program to
access sk_buff") enabled programs of BPF_PROG_TYPE_CGROUP_SKB
type to use ld_abs/ind instructions. However, at this point,
we cannot use them, since offsets relative to SKF_LL_OFF will
end up pointing skb_mac_header(skb) out of bounds since in the
egress path it is not yet set at that point in time, but only
after __dev_queue_xmit() did a general reset on the mac header.
bpf_internal_load_pointer_neg_helper() will then end up reading
data from a wrong offset.
BPF_PROG_TYPE_CGROUP_SKB programs can use bpf_skb_load_bytes()
already to access packet data, which is also more flexible than
the insns carried over from cBPF.
Fixes: fb9a307d11d6 ("bpf: Allow CGROUP_SKB eBPF program to access sk_buff")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Chenbo Feng <fengc@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8acae64df255..14ccb0759fa4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2426,7 +2426,6 @@ static bool may_access_skb(enum bpf_prog_type type) case BPF_PROG_TYPE_SOCKET_FILTER: case BPF_PROG_TYPE_SCHED_CLS: case BPF_PROG_TYPE_SCHED_ACT: - case BPF_PROG_TYPE_CGROUP_SKB: return true; default: return false; |