Unverified Commit 30580dc9 authored by Alexander Mikhalitsyn's avatar Alexander Mikhalitsyn Committed by Christian Brauner
Browse files

af_unix: introduce and use scm_replace_pid() helper 



Existing logic in __scm_send() related to filling an struct scm_cookie
with a proper struct pid reference is already pretty tricky. Let's
simplify it a bit by introducing a new helper. This helper will be
extended in one of the next patches.

Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Kuniyuki Iwashima <kuniyu@google.com>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Luca Boccassi <bluca@debian.org>
Cc: David Rheinsberg <david@readahead.eu>
Signed-off-by: default avatarAlexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Link: https://lore.kernel.org/20250703222314.309967-4-aleksandr.mikhalitsyn@canonical.com


Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent ee479762

net/core/scm.c

+19 −3
Original line number Diff line number Diff line
@@ -145,6 +145,16 @@ void __scm_destroy(struct scm_cookie *scm) 
}

EXPORT_SYMBOL(__scm_destroy);



static inline int scm_replace_pid(struct scm_cookie *scm, struct pid *pid)

{

	/* drop all previous references */

	scm_destroy_cred(scm);



	scm->pid = pid;

	scm->creds.pid = pid_vnr(pid);

	return 0;

}



int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)

{

	const struct proto_ops *ops = READ_ONCE(sock->ops);
@@ -189,15 +199,21 @@ int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p) 
			if (err)

				goto error;



			p->creds.pid = creds.pid;

			if (!p->pid || pid_vnr(p->pid) != creds.pid) {

				struct pid *pid;

				err = -ESRCH;

				pid = find_get_pid(creds.pid);

				if (!pid)

					goto error;

				put_pid(p->pid);

				p->pid = pid;



				/* pass a struct pid reference from

				 * find_get_pid() to scm_replace_pid().

				 */

				err = scm_replace_pid(p, pid);

				if (err) {

					put_pid(pid);

					goto error;

				}

			}



			err = -EINVAL;