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authorDaniel Borkmann2017-06-06 18:38:04 +0200
committerDavid S. Miller2017-06-06 16:39:48 -0400
commit92046578ac88e0a93f8ef03240e6c832b0189aa7 (patch)
tree3706fad432d13a5174698b4a0fd3e9d5446c5daf /kernel/bpf
parentfeec084a7cf49adb4a87bea9867fb2ba99821f48 (diff)
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/bpf')
-rw-r--r--kernel/bpf/verifier.c1
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;