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af_unix: rework unix_maybe_add_creds() to allow sleep

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As a preparation for the next patches we need to allow sleeping
in unix_maybe_add_creds() and also return err. Currently, we can't do
that as unix_maybe_add_creds() is being called under unix_state_lock().
There is no need for this, really. So let's move call sites of
this helper a bit and do necessary function signature changes.

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: 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>
Link: https://lore.kernel.org/20250703222314.309967-2-aleksandr.mikhalitsyn@canonical.com
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Alexander Mikhalitsyn
2025-07-04 00:23:05 +02:00
committed by Christian Brauner
parent 867673063e
commit 9bedee7cdf
1 changed files with 25 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
net/unix/af_unix.c
View File

@@ -1955,21 +1955,30 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen
return err;
}
/*
/**
* unix_maybe_add_creds() - Adds current task uid/gid and struct pid to skb if needed.
* @skb: skb to attach creds to.
* @sk: Sender sock.
* @other: Receiver sock.
*
* Some apps rely on write() giving SCM_CREDENTIALS
* We include credentials if source or destination socket
* asserted SOCK_PASSCRED.
*
* Return: On success zero, on error a negative error code is returned.
*/
static void unix_maybe_add_creds(struct sk_buff *skb, const struct sock *sk,
const struct sock *other)
static int unix_maybe_add_creds(struct sk_buff *skb, const struct sock *sk,
const struct sock *other)
{
if (UNIXCB(skb).pid)
return;
return 0;
if (unix_may_passcred(sk) || unix_may_passcred(other)) {
UNIXCB(skb).pid = get_pid(task_tgid(current));
current_uid_gid(&UNIXCB(skb).uid, &UNIXCB(skb).gid);
}
return 0;
}
static bool unix_skb_scm_eq(struct sk_buff *skb,
@@ -2104,6 +2113,10 @@ lookup:
goto out_sock_put;
}
err = unix_maybe_add_creds(skb, sk, other);
if (err)
goto out_sock_put;
restart:
sk_locked = 0;
unix_state_lock(other);
@@ -2212,7 +2225,6 @@ restart_locked:
if (sock_flag(other, SOCK_RCVTSTAMP))
__net_timestamp(skb);
unix_maybe_add_creds(skb, sk, other);
scm_stat_add(other, skb);
skb_queue_tail(&other->sk_receive_queue, skb);
unix_state_unlock(other);
@@ -2256,6 +2268,10 @@ static int queue_oob(struct sock *sk, struct msghdr *msg, struct sock *other,
if (err < 0)
goto out;
err = unix_maybe_add_creds(skb, sk, other);
if (err)
goto out;
skb_put(skb, 1);
err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, 1);
@@ -2275,7 +2291,6 @@ static int queue_oob(struct sock *sk, struct msghdr *msg, struct sock *other,
goto out_unlock;
}
unix_maybe_add_creds(skb, sk, other);
scm_stat_add(other, skb);
spin_lock(&other->sk_receive_queue.lock);
@@ -2369,6 +2384,10 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
fds_sent = true;
err = unix_maybe_add_creds(skb, sk, other);
if (err)
goto out_free;
if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) {
skb->ip_summed = CHECKSUM_UNNECESSARY;
err = skb_splice_from_iter(skb, &msg->msg_iter, size,
@@ -2399,7 +2418,6 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
goto out_free;
}
unix_maybe_add_creds(skb, sk, other);
scm_stat_add(other, skb);
skb_queue_tail(&other->sk_receive_queue, skb);
unix_state_unlock(other);