[PATCH] selinux: Read sk->sk_family once in selinux_socket_bind()

[Mickaël Salaün]

This looks good be there are other places using sk->sk_family that
should also be fixed.

On Thu, Dec 12, 2024 at 06:20:00PM +0800, Mikhail Ivanov wrote:
> selinux_socket_bind() is called without holding the socket lock.
> 
> Use READ_ONCE() to safely read sk->sk_family for IPv6 socket in case
> of lockless transformation to IPv4 socket via IPV6_ADDRFORM [1].
> 
> [1] https://lore.kernel.org/all/20240202095404.183274-1-edumazet@google.com/
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Mikhail Ivanov <ivanov.mikhail1 at huawei-partners.com>
> ---
>  security/selinux/hooks.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 5e5f3398f39d..b7adff2cf5f6 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -4715,8 +4715,10 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in
>  	if (err)
>  		goto out;
>  
> +	/* IPV6_ADDRFORM can change sk->sk_family under us. */
> +	family = READ_ONCE(sk->sk_family);
> +
>  	/* If PF_INET or PF_INET6, check name_bind permission for the port. */
> -	family = sk->sk_family;
>  	if (family == PF_INET || family == PF_INET6) {
>  		char *addrp;
>  		struct common_audit_data ad;
> 
> base-commit: 034294fbfdf0ded4f931f9503d2ca5bbf8b9aebd
> -- 
> 2.34.1
> 
>