[PATCH v3] selinux: Fix error priority for bind with AF_UNSPEC on PF_INET6 socket

[PATCH v3] selinux: Fix error priority for bind with AF_UNSPEC on PF_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@parisplace.org>
Cc: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Reported-by: Muhammad Usama Anjum <usama.anjum@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@digikod.net>
---

Changes since v2:
https://lore.kernel.org/r/20231229171922.106190-1-mic@digikod.net
* Add !PF_INET6 check and comments (suggested by Paul).
* s/AF_INET/PF_INET/g (cosmetic change).

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 | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index feda711c6b7b..8b1429eb2db5 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4667,6 +4667,13 @@ 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 == PF_INET6) {
+					/* Length check from inet6_bind_sk() */
+					if (addrlen < SIN6_LEN_RFC2133)
+						return -EINVAL;
+					/* Family check from __inet6_bind() */
+					goto err_af;
+				}
 				/* see __inet_bind(), we only want to allow
 				 * AF_UNSPEC if the address is INADDR_ANY
 				 */
-- 
2.43.0

Re: [PATCH v3] selinux: Fix error priority for bind with AF_UNSPEC on PF_INET6 socket

[Muhammad Usama Anjum]

On 1/3/24 9:34 PM, Mickaël Salaün wrote:
> 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@parisplace.org>
> Cc: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
> Reported-by: Muhammad Usama Anjum <usama.anjum@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@digikod.net>
Thank you Mickaël for the patch. Tested patch on v6.7-rc8.

Tested-by: Muhammad Usama Anjum <usama.anjum@collabora.com>

> ---
> 
> Changes since v2:
> https://lore.kernel.org/r/20231229171922.106190-1-mic@digikod.net
> * Add !PF_INET6 check and comments (suggested by Paul).
> * s/AF_INET/PF_INET/g (cosmetic change).
> 
> 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 | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index feda711c6b7b..8b1429eb2db5 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -4667,6 +4667,13 @@ 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 == PF_INET6) {
> +					/* Length check from inet6_bind_sk() */
> +					if (addrlen < SIN6_LEN_RFC2133)
> +						return -EINVAL;
> +					/* Family check from __inet6_bind() */
> +					goto err_af;
> +				}
>  				/* see __inet_bind(), we only want to allow
>  				 * AF_UNSPEC if the address is INADDR_ANY
>  				 */

-- 
BR,
Muhammad Usama Anjum

Re: [PATCH v3] selinux: Fix error priority for bind with AF_UNSPEC on PF_INET6 socket

[Paul Moore]

On Thu, Jan 4, 2024 at 6:40 AM Muhammad Usama Anjum
<usama.anjum@collabora.com> wrote:
>
> On 1/3/24 9:34 PM, Mickaël Salaün wrote:
> > 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@parisplace.org>
> > Cc: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
> > Cc: Paul Moore <paul@paul-moore.com>
> > Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
> > Reported-by: Muhammad Usama Anjum <usama.anjum@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@digikod.net>
> Thank you Mickaël for the patch. Tested patch on v6.7-rc8.
>
> Tested-by: Muhammad Usama Anjum <usama.anjum@collabora.com>

This looks good to me, and since it is rather trivial I'm going to go
ahead and merge this into selinux/next so it should go up to Linus
during the upcoming merge window.

Thanks everyone!

-- 
paul-moore.com