diff options
| author | YiFei Zhu <zhuyifei1999@gmail.com> | 2020-06-10 13:41:39 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-06-24 17:50:43 +0200 |
| commit | 9777d12a8b232b8134401cd56c9027caa9fe59c6 (patch) | |
| tree | 21d148e1365ec6e5b43ca3d9c0bb9cc7f6e8e514 /net/core | |
| parent | 0eb4e1573ffd0721421a70727622c5a242643ea6 (diff) | |
net/filter: Permit reading NET in load_bytes_relative when MAC not set
[ Upstream commit 0f5d82f187e1beda3fe7295dfc500af266a5bd80 ]
Added a check in the switch case on start_header that checks for
the existence of the header, and in the case that MAC is not set
and the caller requests for MAC, -EFAULT. If the caller requests
for NET then MAC's existence is completely ignored.
There is no function to check NET header's existence and as far
as cgroup_skb/egress is concerned it should always be set.
Removed for ptr >= the start of header, considering offset is
bounded unsigned and should always be true. len <= end - mac is
redundant to ptr + len <= end.
Fixes: 3eee1f75f2b9 ("bpf: fix bpf_skb_load_bytes_relative pkt length check")
Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/76bb820ddb6a95f59a772ecbd8c8a336f646b362.1591812755.git.zhuyifei@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/filter.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index f1f2304822e3..a0a492f7cf9c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1766,25 +1766,27 @@ BPF_CALL_5(bpf_skb_load_bytes_relative, const struct sk_buff *, skb, u32, offset, void *, to, u32, len, u32, start_header) { u8 *end = skb_tail_pointer(skb); - u8 *net = skb_network_header(skb); - u8 *mac = skb_mac_header(skb); - u8 *ptr; + u8 *start, *ptr; - if (unlikely(offset > 0xffff || len > (end - mac))) + if (unlikely(offset > 0xffff)) goto err_clear; switch (start_header) { case BPF_HDR_START_MAC: - ptr = mac + offset; + if (unlikely(!skb_mac_header_was_set(skb))) + goto err_clear; + start = skb_mac_header(skb); break; case BPF_HDR_START_NET: - ptr = net + offset; + start = skb_network_header(skb); break; default: goto err_clear; } - if (likely(ptr >= mac && ptr + len <= end)) { + ptr = start + offset; + + if (likely(ptr + len <= end)) { memcpy(to, ptr, len); return 0; } |