From 4da6a196f93b1af7612340e8c1ad8ce71e18f955 Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Sat, 11 Jan 2020 06:11:59 +0000 Subject: bpf: Sockmap/tls, during free we may call tcp_bpf_unhash() in loop When a sockmap is free'd and a socket in the map is enabled with tls we tear down the bpf context on the socket, the psock struct and state, and then call tcp_update_ulp(). The tcp_update_ulp() call is to inform the tls stack it needs to update its saved sock ops so that when the tls socket is later destroyed it doesn't try to call the now destroyed psock hooks. This is about keeping stacked ULPs in good shape so they always have the right set of stacked ops. However, recently unhash() hook was removed from TLS side. But, the sockmap/bpf side is not doing any extra work to update the unhash op when is torn down instead expecting TLS side to manage it. So both TLS and sockmap believe the other side is managing the op and instead no one updates the hook so it continues to point at tcp_bpf_unhash(). When unhash hook is called we call tcp_bpf_unhash() which detects the psock has already been destroyed and calls sk->sk_prot_unhash() which calls tcp_bpf_unhash() yet again and so on looping and hanging the core. To fix have sockmap tear down logic fixup the stale pointer. Fixes: 5d92e631b8be ("net/tls: partially revert fix transition through disconnect with close") Reported-by: syzbot+83979935eb6304f8cd46@syzkaller.appspotmail.com Signed-off-by: John Fastabend Signed-off-by: Daniel Borkmann Reviewed-by: Jakub Sitnicki Acked-by: Song Liu Cc: stable@vger.kernel.org Link: https://lore.kernel.org/bpf/20200111061206.8028-2-john.fastabend@gmail.com --- include/linux/skmsg.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/skmsg.h') diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h index ef7031f8a304..b6afe01f8592 100644 --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -358,6 +358,7 @@ static inline void sk_psock_update_proto(struct sock *sk, static inline void sk_psock_restore_proto(struct sock *sk, struct sk_psock *psock) { + sk->sk_prot->unhash = psock->saved_unhash; sk->sk_write_space = psock->saved_write_space; if (psock->sk_proto) { -- cgit v1.2.3 From 33bfe20dd7117dd81fd896a53f743a233e1ad64f Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Sat, 11 Jan 2020 06:12:01 +0000 Subject: bpf: Sockmap/tls, push write_space updates through ulp updates When sockmap sock with TLS enabled is removed we cleanup bpf/psock state and call tcp_update_ulp() to push updates to TLS ULP on top. However, we don't push the write_space callback up and instead simply overwrite the op with the psock stored previous op. This may or may not be correct so to ensure we don't overwrite the TLS write space hook pass this field to the ULP and have it fixup the ctx. This completes a previous fix that pushed the ops through to the ULP but at the time missed doing this for write_space, presumably because write_space TLS hook was added around the same time. Fixes: 95fa145479fbc ("bpf: sockmap/tls, close can race with map free") Signed-off-by: John Fastabend Signed-off-by: Daniel Borkmann Reviewed-by: Jakub Sitnicki Acked-by: Jonathan Lemon Cc: stable@vger.kernel.org Link: https://lore.kernel.org/bpf/20200111061206.8028-4-john.fastabend@gmail.com --- include/linux/skmsg.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'include/linux/skmsg.h') diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h index b6afe01f8592..14d61bba0b79 100644 --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -359,17 +359,21 @@ static inline void sk_psock_restore_proto(struct sock *sk, struct sk_psock *psock) { sk->sk_prot->unhash = psock->saved_unhash; - sk->sk_write_space = psock->saved_write_space; if (psock->sk_proto) { struct inet_connection_sock *icsk = inet_csk(sk); bool has_ulp = !!icsk->icsk_ulp_data; - if (has_ulp) - tcp_update_ulp(sk, psock->sk_proto); - else + if (has_ulp) { + tcp_update_ulp(sk, psock->sk_proto, + psock->saved_write_space); + } else { sk->sk_prot = psock->sk_proto; + sk->sk_write_space = psock->saved_write_space; + } psock->sk_proto = NULL; + } else { + sk->sk_write_space = psock->saved_write_space; } } -- cgit v1.2.3