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$inet_sctp6_SCTP_SOCKOPT_PEELOFF() This patch is to block this call when peeling one assoc off from one netns to another one, so that the netns of all transport would not go out-sync with the key in hashtable. Note that this patch didn't fix it by rehashing transports, as it's difficult to handle the situation when the tuple is already in use in the new netns. Besides, no one would like to peel off one assoc to another netns, considering ipaddrs, ifaces, etc. are usually different. Reported-by: ChunYu Wang Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller --- net/sctp/socket.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net/sctp/socket.c') diff --git a/net/sctp/socket.c b/net/sctp/socket.c index d4730ada7f32..17841ab30798 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -4906,6 +4906,10 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp) struct socket *sock; int err = 0; + /* Do not peel off from one netns to another one. */ + if (!net_eq(current->nsproxy->net_ns, sock_net(sk))) + return -EINVAL; + if (!asoc) return -EINVAL; -- cgit v1.2.3 From d04adf1b355181e737b6b1e23d801b07f0b7c4c0 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sat, 28 Oct 2017 02:13:29 +0800 Subject: sctp: reset owner sk for data chunks on out queues when migrating a sock Now when migrating sock to another one in sctp_sock_migrate(), it only resets owner sk for the data in receive queues, not the chunks on out queues. It would cause that data chunks length on the sock is not consistent with sk sk_wmem_alloc. When closing the sock or freeing these chunks, the old sk would never be freed, and the new sock may crash due to the overflow sk_wmem_alloc. syzbot found this issue with this series: r0 = socket$inet_sctp() sendto$inet(r0) listen(r0) accept4(r0) close(r0) Although listen() should have returned error when one TCP-style socket is in connecting (I may fix this one in another patch), it could also be reproduced by peeling off an assoc. This issue is there since very beginning. This patch is to reset owner sk for the chunks on out queues so that sk sk_wmem_alloc has correct value after accept one sock or peeloff an assoc to one sock. Note that when resetting owner sk for chunks on outqueue, it has to sctp_clear_owner_w/skb_orphan chunks before changing assoc->base.sk first and then sctp_set_owner_w them after changing assoc->base.sk, due to that sctp_wfree and it's callees are using assoc->base.sk. Reported-by: Dmitry Vyukov Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- net/sctp/socket.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'net/sctp/socket.c') diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 17841ab30798..6f45d1713452 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -170,6 +170,36 @@ static inline void sctp_set_owner_w(struct sctp_chunk *chunk) sk_mem_charge(sk, chunk->skb->truesize); } +static void sctp_clear_owner_w(struct sctp_chunk *chunk) +{ + skb_orphan(chunk->skb); +} + +static void sctp_for_each_tx_datachunk(struct sctp_association *asoc, + void (*cb)(struct sctp_chunk *)) + +{ + struct sctp_outq *q = &asoc->outqueue; + struct sctp_transport *t; + struct sctp_chunk *chunk; + + list_for_each_entry(t, &asoc->peer.transport_addr_list, transports) + list_for_each_entry(chunk, &t->transmitted, transmitted_list) + cb(chunk); + + list_for_each_entry(chunk, &q->retransmit, list) + cb(chunk); + + list_for_each_entry(chunk, &q->sacked, list) + cb(chunk); + + list_for_each_entry(chunk, &q->abandoned, list) + cb(chunk); + + list_for_each_entry(chunk, &q->out_chunk_list, list) + cb(chunk); +} + /* Verify that this is a valid address. */ static inline int sctp_verify_addr(struct sock *sk, union sctp_addr *addr, int len) @@ -8212,7 +8242,9 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk, * paths won't try to lock it and then oldsk. */ lock_sock_nested(newsk, SINGLE_DEPTH_NESTING); + sctp_for_each_tx_datachunk(assoc, sctp_clear_owner_w); sctp_assoc_migrate(assoc, newsk); + sctp_for_each_tx_datachunk(assoc, sctp_set_owner_w); /* If the association on the newsk is already closed before accept() * is called, set RCV_SHUTDOWN flag. -- cgit v1.2.3