netdev - Re: [PATCH] selinux: Read sk->sk_family once in selinux_socket

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Message-ID: <CAEjxPJ6+Dvx2f1+LKe4VdFjwZ6vg=fBXFZcfkoGXtXBzu7fL1g@mail.gmail.com>
Date: Tue, 7 Jan 2025 15:13:42 -0500
From: Stephen Smalley <stephen.smalley.work@...il.com>
To: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>
Cc: paul@...l-moore.com, mic@...ikod.net, selinux@...r.kernel.org, 
	omosnace@...hat.com, linux-security-module@...r.kernel.org, 
	netdev@...r.kernel.org, yusongping@...wei.com, artem.kuzin@...wei.com, 
	konstantin.meskhidze@...wei.com
Subject: Re: [PATCH] selinux: Read sk->sk_family once in selinux_socket_bind()

On Thu, Dec 12, 2024 at 5:20 AM Mikhail Ivanov
<ivanov.mikhail1@...wei-partners.com> 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@...wei-partners.com>

Acked-by: Stephen Smalley <stephen.smalley.work@...il.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
>