netdev - [PATCH bpf 2/5] tcp, ulp: fix leftover icsk_ulp

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 16 Aug 2018 21:49:07 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     alexei.starovoitov@...il.com
Cc:     john.fastabend@...il.com, netdev@...r.kernel.org,
        Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH bpf 2/5] tcp, ulp: fix leftover icsk_ulp_ops preventing sock from reattach

I found that in BPF sockmap programs once we either delete a socket
from the map or we updated a map slot and the old socket was purged
from the map that these socket can never get reattached into a map
even though their related psock has been dropped entirely at that
point.

Reason is that tcp_cleanup_ulp() leaves the old icsk->icsk_ulp_ops
intact, so that on the next tcp_set_ulp_id() the kernel returns an
-EEXIST thinking there is still some active ULP attached.

BPF sockmap is the only one that has this issue as the other user,
kTLS, only calls tcp_cleanup_ulp() from tcp_v4_destroy_sock() whereas
sockmap semantics allow dropping the socket from the map with all
related psock state being cleaned up.

Fixes: 1aa12bdf1bfb ("bpf: sockmap, add sock close() hook to remove socks")
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: John Fastabend <john.fastabend@...il.com>
---
 net/ipv4/tcp_ulp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/tcp_ulp.c b/net/ipv4/tcp_ulp.c
index 7dd44b6..a5995bb 100644
--- a/net/ipv4/tcp_ulp.c
+++ b/net/ipv4/tcp_ulp.c
@@ -129,6 +129,8 @@ void tcp_cleanup_ulp(struct sock *sk)
 	if (icsk->icsk_ulp_ops->release)
 		icsk->icsk_ulp_ops->release(sk);
 	module_put(icsk->icsk_ulp_ops->owner);
+
+	icsk->icsk_ulp_ops = NULL;
 }

 /* Change upper layer protocol for socket */
-- 
2.9.5