diff options
| author | Florian Westphal | 2020-01-29 15:54:46 +0100 |
|---|---|---|
| committer | David S. Miller | 2020-01-29 17:45:20 +0100 |
| commit | ae2dd7164943e03644293af92802550d052632e6 (patch) | |
| tree | 50fc4f81068aa6bb1298d0db0d974571b85a9295 /net/mptcp | |
| parent | b2c5b614ca6ed460144788e7f9634569cc0c7b51 (diff) | |
mptcp: handle tcp fallback when using syn cookies
We can't deal with syncookie mode yet, the syncookie rx path will create
tcp reqsk, i.e. we get OOB access because we treat tcp reqsk as mptcp reqsk one:
TCP: SYN flooding on port 20002. Sending cookies.
BUG: KASAN: slab-out-of-bounds in subflow_syn_recv_sock+0x451/0x4d0 net/mptcp/subflow.c:191
Read of size 1 at addr ffff8881167bc148 by task syz-executor099/2120
subflow_syn_recv_sock+0x451/0x4d0 net/mptcp/subflow.c:191
tcp_get_cookie_sock+0xcf/0x520 net/ipv4/syncookies.c:209
cookie_v6_check+0x15a5/0x1e90 net/ipv6/syncookies.c:252
tcp_v6_cookie_check net/ipv6/tcp_ipv6.c:1123 [inline]
[..]
Bug can be reproduced via "sysctl net.ipv4.tcp_syncookies=2".
Note that MPTCP should work with syncookies (4th ack would carry needed
state), but it appears better to sort that out in -next so do tcp
fallback for now.
I removed the MPTCP ifdef for tcp_rsk "is_mptcp" member because
if (IS_ENABLED()) is easier to read than "#ifdef IS_ENABLED()/#endif" pair.
Cc: Eric Dumazet <edumazet@google.com>
Fixes: cec37a6e41aae7bf ("mptcp: Handle MP_CAPABLE options for outgoing connections")
Reported-by: Christoph Paasch <cpaasch@apple.com>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/mptcp')
| -rw-r--r-- | net/mptcp/subflow.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 205dca1c30b7..c90c0e6ffb82 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -186,6 +186,9 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn); + if (tcp_rsk(req)->is_mptcp == 0) + goto create_child; + /* if the sk is MP_CAPABLE, we try to fetch the client key */ subflow_req = mptcp_subflow_rsk(req); if (subflow_req->mp_capable) { @@ -769,7 +772,7 @@ static void subflow_ulp_clone(const struct request_sock *req, struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk); struct mptcp_subflow_context *new_ctx; - if (!subflow_req->mp_capable) { + if (!tcp_rsk(req)->is_mptcp || !subflow_req->mp_capable) { subflow_ulp_fallback(newsk, old_ctx); return; } |