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authorPaolo Abeni <pabeni@redhat.com>2024-03-29 19:50:36 +0100
committerJakub Kicinski <kuba@kernel.org>2024-04-02 05:43:24 +0200
commitfcf4692fa39e86a590c14a4af2de704e1d20a3b5 (patch)
treeb8333ea8be6d6127cc159ac2d89e1ef979ccf2d7
parentselftests: reuseaddr_conflict: add missing new line at the end of the output (diff)
downloadlinux-fcf4692fa39e86a590c14a4af2de704e1d20a3b5.tar.xz
linux-fcf4692fa39e86a590c14a4af2de704e1d20a3b5.zip
mptcp: prevent BPF accessing lowat from a subflow socket.
Alexei reported the following splat: WARNING: CPU: 32 PID: 3276 at net/mptcp/subflow.c:1430 subflow_data_ready+0x147/0x1c0 Modules linked in: dummy bpf_testmod(O) [last unloaded: bpf_test_no_cfi(O)] CPU: 32 PID: 3276 Comm: test_progs Tainted: GO 6.8.0-12873-g2c43c33bfd23 Call Trace: <TASK> mptcp_set_rcvlowat+0x79/0x1d0 sk_setsockopt+0x6c0/0x1540 __bpf_setsockopt+0x6f/0x90 bpf_sock_ops_setsockopt+0x3c/0x90 bpf_prog_509ce5db2c7f9981_bpf_test_sockopt_int+0xb4/0x11b bpf_prog_dce07e362d941d2b_bpf_test_socket_sockopt+0x12b/0x132 bpf_prog_348c9b5faaf10092_skops_sockopt+0x954/0xe86 __cgroup_bpf_run_filter_sock_ops+0xbc/0x250 tcp_connect+0x879/0x1160 tcp_v6_connect+0x50c/0x870 mptcp_connect+0x129/0x280 __inet_stream_connect+0xce/0x370 inet_stream_connect+0x36/0x50 bpf_trampoline_6442491565+0x49/0xef inet_stream_connect+0x5/0x50 __sys_connect+0x63/0x90 __x64_sys_connect+0x14/0x20 The root cause of the issue is that bpf allows accessing mptcp-level proto_ops from a tcp subflow scope. Fix the issue detecting the problematic call and preventing any action. Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/482 Fixes: 5684ab1a0eff ("mptcp: give rcvlowat some love") Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Mat Martineau <martineau@kernel.org> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://lore.kernel.org/r/d8cb7d8476d66cb0812a6e29cd1e626869d9d53e.1711738080.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
-rw-r--r--net/mptcp/sockopt.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index dcd1c76d2a3b..73fdf423de44 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -1493,6 +1493,10 @@ int mptcp_set_rcvlowat(struct sock *sk, int val)
struct mptcp_subflow_context *subflow;
int space, cap;
+ /* bpf can land here with a wrong sk type */
+ if (sk->sk_protocol == IPPROTO_TCP)
+ return -EINVAL;
+
if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
cap = sk->sk_rcvbuf >> 1;
else