From df80cd9b28b9ebaa284a41df611dbf3a2d05ca74 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Tue, 17 Oct 2017 23:26:10 +0800 Subject: sctp: do not peel off an assoc from one netns to another one Now when peeling off an association to the sock in another netns, all transports in this assoc are not to be rehashed and keep use the old key in hashtable. As a transport uses sk->net as the hash key to insert into hashtable, it would miss removing these transports from hashtable due to the new netns when closing the sock and all transports are being freeed, then later an use-after-free issue could be caused when looking up an asoc and dereferencing those transports. This is a very old issue since very beginning, ChunYu found it with syzkaller fuzz testing with this series: socket$inet6_sctp() bind$inet6() sendto$inet6() unshare(0x40000000) getsockopt$inet_sctp6_SCTP_GET_ASSOC_ID_LIST() getsockopt$inet_sctp6_SCTP_SOCKOPT_PEELOFF() This patch is to block this call when peeling one assoc off from one netns to another one, so that the netns of all transport would not go out-sync with the key in hashtable. Note that this patch didn't fix it by rehashing transports, as it's difficult to handle the situation when the tuple is already in use in the new netns. Besides, no one would like to peel off one assoc to another netns, considering ipaddrs, ifaces, etc. are usually different. Reported-by: ChunYu Wang Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller --- net/sctp/socket.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net/sctp') diff --git a/net/sctp/socket.c b/net/sctp/socket.c index d4730ada7f32..17841ab30798 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -4906,6 +4906,10 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp) struct socket *sock; int err = 0; + /* Do not peel off from one netns to another one. */ + if (!net_eq(current->nsproxy->net_ns, sock_net(sk))) + return -EINVAL; + if (!asoc) return -EINVAL; -- cgit v1.2.3 From 1cc276cec9ec574d41cf47dfc0f51406b6f26ab4 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Wed, 18 Oct 2017 21:37:49 +0800 Subject: sctp: add the missing sock_owned_by_user check in sctp_icmp_redirect Now sctp processes icmp redirect packet in sctp_icmp_redirect where it calls sctp_transport_dst_check in which tp->dst can be released. The problem is before calling sctp_transport_dst_check, it doesn't check sock_owned_by_user, which means tp->dst could be freed while a process is accessing it with owning the socket. An use-after-free issue could be triggered by this. This patch is to fix it by checking sock_owned_by_user before calling sctp_transport_dst_check in sctp_icmp_redirect, so that it would not release tp->dst if users still hold sock lock. Besides, the same issue fixed in commit 45caeaa5ac0b ("dccp/tcp: fix routing redirect race") on sctp also needs this check. Fixes: 55be7a9c6074 ("ipv4: Add redirect support to all protocol icmp error handlers") Reported-by: Eric Dumazet Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller --- net/sctp/input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/sctp') diff --git a/net/sctp/input.c b/net/sctp/input.c index 92a07141fd07..34f10e75f3b9 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -421,7 +421,7 @@ void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t, { struct dst_entry *dst; - if (!t) + if (sock_owned_by_user(sk) || !t) return; dst = sctp_transport_dst_check(t); if (dst) -- cgit v1.2.3