On 10/3/2024 8:45 PM, Mickaël Salaün wrote:

Please also add Matthieu in Cc for the network patch series.

On Thu, Oct 03, 2024 at 10:39:31PM +0800, Mikhail Ivanov wrote:

quoted

Do not check TCP access right if socket protocol is not IPPROTO_TCP.
LANDLOCK_ACCESS_NET_BIND_TCP and LANDLOCK_ACCESS_NET_CONNECT_TCP
should not restrict bind(2) and connect(2) for non-TCP protocols
(SCTP, MPTCP, SMC).

Closes: https://github.com/landlock-lsm/linux/issues/40
Fixes: fff69fb03dde ("landlock: Support network rules with TCP bind and connect")
Signed-off-by: Mikhail Ivanov <redacted>
---
  security/landlock/net.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/landlock/net.c b/security/landlock/net.c
index bc3d943a7118..6f59dd98bb13 100644
--- a/security/landlock/net.c
+++ b/security/landlock/net.c

@@ -68,7 +68,7 @@ static int current_check_access_socket(struct socket *const sock,
  		return -EACCES;
  
  	/* Checks if it's a (potential) TCP socket. */

We can extend this comment to explain that we don't use sk_is_tcp()
because we need to handle the AF_UNSPEC case.

Indeed, I'll do this.

quoted

-	if (sock->type != SOCK_STREAM)
+	if (sock->type != SOCK_STREAM || sock->sk->sk_protocol != IPPROTO_TCP)

I think we should check sock->sk->sk_type instead of sock->type (even if
it should be the same).  To make it simpler, we should only use sk in
current_check_access_socket():
struct sock *sk = sock->sk;

Agreed.

Could you please also do s/__sk_common\.skc_/sk_/g ?

Ofc

Btw, there is probably incorrect read of skc_family in this function
[1]. I'll add READ_ONCE for sk->sk_family.

[1] https://lore.kernel.org/all/20240202095404.183274-1-edumazet@google.com/ (local)

quoted

  		return 0;
  
  	/* Checks for minimal header length to safely read sa_family. */
-- 
2.34.1