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: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
---
v2:
- don't do get_pid() in __scm_replace_pid() [ as Kuniyuki suggested ]
- move __scm_replace_pid() from scm.h to scm.c [ as Kuniyuki suggested ]
v3:
- rename __scm_replace_pid() to scm_replace_pid() [ as Kuniyuki suggested ]
---
net/core/scm.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/net/core/scm.c b/net/core/scm.c
index 0225bd94170f..045ab5bdac7d 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -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;
--
2.43.0