[PATCH v2] selinux: Fix error priority for bind with AF_UNSPEC on AF_INET6 socket

[Mickaël Salaün]

The IPv6 network stack first checks the sockaddr length (-EINVAL error)
before checking the family (-EAFNOSUPPORT error).

This was discovered thanks to commit a549d055a22e ("selftests/landlock:
Add network tests").

Cc: Eric Paris <eparis at parisplace.org>
Cc: Konstantin Meskhidze <konstantin.meskhidze at huawei.com>
Cc: Paul Moore <paul at paul-moore.com>
Cc: Stephen Smalley <stephen.smalley.work at gmail.com>
Reported-by: Muhammad Usama Anjum <usama.anjum at collabora.com>
Closes: https://lore.kernel.org/r/0584f91c-537c-4188-9e4f-04f192565667@collabora.com
Fixes: 0f8db8cc73df ("selinux: add AF_UNSPEC and INADDR_ANY checks to selinux_socket_bind()")
Signed-off-by: Mickaël Salaün <mic at digikod.net>
---

Changes since v1:
https://lore.kernel.org/r/20231228113917.62089-1-mic@digikod.net
* Use the "family" variable (suggested by Paul).
---
 security/selinux/hooks.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index feda711c6b7b..748baa98f623 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4667,6 +4667,9 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in
 				return -EINVAL;
 			addr4 = (struct sockaddr_in *)address;
 			if (family_sa == AF_UNSPEC) {
+				if (family == AF_INET6 &&
+				    addrlen < SIN6_LEN_RFC2133)
+					return -EINVAL;
 				/* see __inet_bind(), we only want to allow
 				 * AF_UNSPEC if the address is INADDR_ANY
 				 */
-- 
2.43.0