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| author | Martin KaFai Lau <kafai@fb.com> | 2019-05-17 23:21:17 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-05-21 16:33:30 +0200 |
| commit | f7355a6c049711ecfbeed573e43d48bee7acb83a (patch) | |
| tree | 975e94b97c1f8b78fd7972b228b0e05027089cd4 /net/core | |
| parent | bpf: fix out-of-bounds read in __bpf_skc_lookup (diff) | |
| download | linux-f7355a6c049711ecfbeed573e43d48bee7acb83a.tar.xz linux-f7355a6c049711ecfbeed573e43d48bee7acb83a.zip | |
bpf: Check sk_fullsock() before returning from bpf_sk_lookup()
The BPF_FUNC_sk_lookup_xxx helpers return RET_PTR_TO_SOCKET_OR_NULL.
Meaning a fullsock ptr and its fullsock's fields in bpf_sock can be
accessed, e.g. type, protocol, mark and priority.
Some new helper, like bpf_sk_storage_get(), also expects
ARG_PTR_TO_SOCKET is a fullsock.
bpf_sk_lookup() currently calls sk_to_full_sk() before returning.
However, the ptr returned from sk_to_full_sk() is not guaranteed
to be a fullsock. For example, it cannot get a fullsock if sk
is in TCP_TIME_WAIT.
This patch checks for sk_fullsock() before returning. If it is not
a fullsock, sock_gen_put() is called if needed and then returns NULL.
Fixes: 6acc9b432e67 ("bpf: Add helper to retrieve socket in BPF")
Cc: Joe Stringer <joe@isovalent.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Joe Stringer <joe@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/filter.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 76f1d99640e2..fdcc504d2dec 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5343,8 +5343,14 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, struct sock *sk = __bpf_skc_lookup(skb, tuple, len, caller_net, ifindex, proto, netns_id, flags); - if (sk) + if (sk) { sk = sk_to_full_sk(sk); + if (!sk_fullsock(sk)) { + if (!sock_flag(sk, SOCK_RCU_FREE)) + sock_gen_put(sk); + return NULL; + } + } return sk; } @@ -5375,8 +5381,14 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, struct sock *sk = bpf_skc_lookup(skb, tuple, len, proto, netns_id, flags); - if (sk) + if (sk) { sk = sk_to_full_sk(sk); + if (!sk_fullsock(sk)) { + if (!sock_flag(sk, SOCK_RCU_FREE)) + sock_gen_put(sk); + return NULL; + } + } return sk; } |