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af_unix: Set sk_peer_pid/sk_peer_cred locklessly for new socket.

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init_peercred() is called in 3 places:

  1. socketpair() : both sockets
  2. connect()    : child socket
  3. listen()     : listening socket

The first two need not hold sk_peer_lock because no one can
touch the socket.

Let's set cred/pid without holding lock for the two cases and
rename the old init_peercred() to update_peercred() to properly
reflect the use case.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Kuniyuki Iwashima 2024-06-20 13:56:21 -07:00 committed by Paolo Abeni
parent 8647ece481
commit faf489e689
1 changed files with 8 additions and 3 deletions
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11
net/unix/af_unix.c
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@ -750,6 +750,12 @@ static void unix_release_sock(struct sock *sk, int embrion)
}
static void init_peercred(struct sock *sk)
{
sk->sk_peer_pid = get_pid(task_tgid(current));
sk->sk_peer_cred = get_current_cred();
}
static void update_peercred(struct sock *sk)
{
const struct cred *old_cred;
struct pid *old_pid;
@ -757,8 +763,7 @@ static void init_peercred(struct sock *sk)
spin_lock(&sk->sk_peer_lock);
old_pid = sk->sk_peer_pid;
old_cred = sk->sk_peer_cred;
sk->sk_peer_pid = get_pid(task_tgid(current));
sk->sk_peer_cred = get_current_cred();
init_peercred(sk);
spin_unlock(&sk->sk_peer_lock);
put_pid(old_pid);
@ -810,7 +815,7 @@ static int unix_listen(struct socket *sock, int backlog)
WRITE_ONCE(sk->sk_state, TCP_LISTEN);
/* set credentials so connect can copy them */
init_peercred(sk);
update_peercred(sk);
err = 0;
out_unlock: