diff options
| author | Michal Luczaj <mhal@rbox.co> | 2024-07-13 21:41:38 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-08-03 08:54:36 +0200 |
| commit | 772f9c31bfde0df64970f17b5995ca02565eb095 (patch) | |
| tree | 8fffb00a4ecb88b35b73bb05a19e52ce1c442d58 | |
| parent | 297a14fde2d3dae36b77ed66e79486d82268b0e3 (diff) | |
af_unix: Disable MSG_OOB handling for sockets in sockmap/sockhash
[ Upstream commit 638f32604385fd23059985da8de918e9c18f0b98 ]
AF_UNIX socket tracks the most recent OOB packet (in its receive queue)
with an `oob_skb` pointer. BPF redirecting does not account for that: when
an OOB packet is moved between sockets, `oob_skb` is left outdated. This
results in a single skb that may be accessed from two different sockets.
Take the easy way out: silently drop MSG_OOB data targeting any socket that
is in a sockmap or a sockhash. Note that such silent drop is akin to the
fate of redirected skb's scm_fp_list (SCM_RIGHTS, SCM_CREDENTIALS).
For symmetry, forbid MSG_OOB in unix_bpf_recvmsg().
Fixes: 314001f0bf92 ("af_unix: Add OOB support")
Suggested-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20240713200218.2140950-2-mhal@rbox.co
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | net/unix/af_unix.c | 41 | ||||
| -rw-r--r-- | net/unix/unix_bpf.c | 3 |
2 files changed, 43 insertions, 1 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 5a26e785ce70..a551be47cb6c 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2624,10 +2624,49 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk, static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor) { + struct unix_sock *u = unix_sk(sk); + struct sk_buff *skb; + int err; + if (unlikely(READ_ONCE(sk->sk_state) != TCP_ESTABLISHED)) return -ENOTCONN; - return unix_read_skb(sk, recv_actor); + mutex_lock(&u->iolock); + skb = skb_recv_datagram(sk, MSG_DONTWAIT, &err); + mutex_unlock(&u->iolock); + if (!skb) + return err; + +#if IS_ENABLED(CONFIG_AF_UNIX_OOB) + if (unlikely(skb == READ_ONCE(u->oob_skb))) { + bool drop = false; + + unix_state_lock(sk); + + if (sock_flag(sk, SOCK_DEAD)) { + unix_state_unlock(sk); + kfree_skb(skb); + return -ECONNRESET; + } + + spin_lock(&sk->sk_receive_queue.lock); + if (likely(skb == u->oob_skb)) { + WRITE_ONCE(u->oob_skb, NULL); + drop = true; + } + spin_unlock(&sk->sk_receive_queue.lock); + + unix_state_unlock(sk); + + if (drop) { + WARN_ON_ONCE(skb_unref(skb)); + kfree_skb(skb); + return -EAGAIN; + } + } +#endif + + return recv_actor(sk, skb); } static int unix_stream_read_generic(struct unix_stream_read_state *state, diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c index bd84785bf8d6..bca2d86ba97d 100644 --- a/net/unix/unix_bpf.c +++ b/net/unix/unix_bpf.c @@ -54,6 +54,9 @@ static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg, struct sk_psock *psock; int copied; + if (flags & MSG_OOB) + return -EOPNOTSUPP; + if (!len) return 0; |