diff options
| author | Lorenz Bauer <lmb@cloudflare.com> | 2020-01-10 16:23:36 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-01-10 21:42:23 +0300 |
| commit | 2e012c74823629d9db27963c79caa3f5b2010746 (patch) | |
| tree | f7076cabc30ef3bea7a5ec1485c1e8449594cb2c /net | |
| parent | e7a5f1f1cd0008e5ad379270a8657e121eedb669 (diff) | |
| download | linux-2e012c74823629d9db27963c79caa3f5b2010746.tar.xz | |
net: bpf: Don't leak time wait and request sockets
It's possible to leak time wait and request sockets via the following
BPF pseudo code:
sk = bpf_skc_lookup_tcp(...)
if (sk)
bpf_sk_release(sk)
If sk->sk_state is TCP_NEW_SYN_RECV or TCP_TIME_WAIT the refcount taken
by bpf_skc_lookup_tcp is not undone by bpf_sk_release. This is because
sk_flags is re-used for other data in both kinds of sockets. The check
!sock_flag(sk, SOCK_RCU_FREE)
therefore returns a bogus result. Check that sk_flags is valid by calling
sk_fullsock. Skip checking SOCK_RCU_FREE if we already know that sk is
not a full socket.
Fixes: edbf8c01de5a ("bpf: add skc_lookup_tcp helper")
Fixes: f7355a6c0497 ("bpf: Check sk_fullsock() before returning from bpf_sk_lookup()")
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200110132336.26099-1-lmb@cloudflare.com
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/filter.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 28b3c258188c..d22d108fc6e3 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5318,8 +5318,7 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, if (sk) { sk = sk_to_full_sk(sk); if (!sk_fullsock(sk)) { - if (!sock_flag(sk, SOCK_RCU_FREE)) - sock_gen_put(sk); + sock_gen_put(sk); return NULL; } } @@ -5356,8 +5355,7 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, if (sk) { sk = sk_to_full_sk(sk); if (!sk_fullsock(sk)) { - if (!sock_flag(sk, SOCK_RCU_FREE)) - sock_gen_put(sk); + sock_gen_put(sk); return NULL; } } @@ -5424,7 +5422,8 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = { BPF_CALL_1(bpf_sk_release, struct sock *, sk) { - if (!sock_flag(sk, SOCK_RCU_FREE)) + /* Only full sockets have sk->sk_flags. */ + if (!sk_fullsock(sk) || !sock_flag(sk, SOCK_RCU_FREE)) sock_gen_put(sk); return 0; } |