From: Paolo Abeni <pabeni@redhat.com>
Date: Tue, 3 Jan 2023 12:19:17 +0100
Subject: net/ulp: prevent ULP without clone op from entering the LISTEN status
Patch-mainline: v6.2-rc3
Git-commit: 2c02d41d71f90a5168391b6a5f2954112ba2307c
References: CVE-2023-0461 bsc#1208787 bsc#1217079
When an ULP-enabled socket enters the LISTEN status, the listener ULP data
pointer is copied inside the child/accepted sockets by sk_clone_lock().
The relevant ULP can take care of de-duplicating the context pointer via
the clone() operation, but only MPTCP and SMC implement such op.
Other ULPs may end-up with a double-free at socket disposal time.
We can't simply clear the ULP data at clone time, as TLS replaces the
socket ops with custom ones assuming a valid TLS ULP context is
available.
Instead completely prevent clone-less ULP sockets from entering the
LISTEN status.
cve/linux-4.12: we do not actually have tcp_ulp_ops::clone() in 4.12 kernel.
Only tls and espintcp are using ULP infrastructure in 4.12 and neither of
those has ->clone() even in mainline; the instances of struct tcp_ulp_ops
in mainline with ->clone() were either added after 4.12 (mptcp) or their ULP
support was added later (smc). Therefore we can simplify the logic to never
allow a ULP socket to listen.
Fixes: 734942cc4ea6 ("tcp: ULP infrastructure")
Reported-by: slipper <slipper.alive@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/4b80c3d1dbe3d0ab072f80450c202d9bc88b4b03.1672740602.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Michal Kubecek <mkubecek@suse.cz>
---
net/ipv4/inet_connection_sock.c | 18 +++++++++++++++++-
net/ipv4/tcp_ulp.c | 5 +++++
2 files changed, 22 insertions(+), 1 deletion(-)
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -899,11 +899,27 @@ void inet_csk_prepare_forced_close(struct sock *sk)
}
EXPORT_SYMBOL(inet_csk_prepare_forced_close);
+static int inet_ulp_can_listen(const struct sock *sk)
+{
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+
+ /* no icsk->icsk_ulp_ops->clone in 5.3 kernel */
+ if (icsk->icsk_ulp_ops)
+ return -EINVAL;
+
+ return 0;
+}
+
int inet_csk_listen_start(struct sock *sk, int backlog)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct inet_sock *inet = inet_sk(sk);
- int err = -EADDRINUSE;
+ int err;
+
+ err = inet_ulp_can_listen(sk);
+ if (unlikely(err))
+ return err;
+ err = -EADDRINUSE;
reqsk_queue_alloc(&icsk->icsk_accept_queue);
--- a/net/ipv4/tcp_ulp.c
+++ b/net/ipv4/tcp_ulp.c
@@ -118,6 +118,11 @@ static int __tcp_set_ulp(struct sock *sk, const struct tcp_ulp_ops *ulp_ops)
if (icsk->icsk_ulp_ops)
goto out_err;
+ err = -EINVAL;
+ /* no ulp_ops->clone in 4.12 kernel */
+ if (sk->sk_state == TCP_LISTEN)
+ goto out_err;
+
err = ulp_ops->init(sk);
if (err)
goto out_err;