1 files changed, 47 insertions, 57 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index f78a2492826f..bd507f74e35e 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -765,6 +765,11 @@ static void copy_peercred(struct sock *sk, struct sock *peersk)
 	spin_unlock(&sk->sk_peer_lock);
 }
 
+static bool unix_may_passcred(const struct sock *sk)
+{
+	return sk->sk_scm_credentials || sk->sk_scm_pidfd;
+}
+
 static int unix_listen(struct socket *sock, int backlog)
 {
 	int err;
@@ -950,13 +955,6 @@ static void unix_close(struct sock *sk, long timeout)
 	 */
 }
 
-static void unix_unhash(struct sock *sk)
-{
-	/* Nothing to do here, unix socket does not need a ->unhash().
-	 * This is merely for sockmap.
-	 */
-}
-
 static bool unix_bpf_bypass_getsockopt(int level, int optname)
 {
 	if (level == SOL_SOCKET) {
@@ -987,7 +985,6 @@ struct proto unix_stream_proto = {
 	.owner			= THIS_MODULE,
 	.obj_size		= sizeof(struct unix_sock),
 	.close			= unix_close,
-	.unhash			= unix_unhash,
 	.bpf_bypass_getsockopt	= unix_bpf_bypass_getsockopt,
 #ifdef CONFIG_BPF_SYSCALL
 	.psock_update_sk_prot	= unix_stream_bpf_update_proto,
@@ -1018,6 +1015,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
 
 	sock_init_data(sock, sk);
 
+	sk->sk_scm_rights	= 1;
 	sk->sk_hash		= unix_unbound_hash(sk);
 	sk->sk_allocation	= GFP_KERNEL_ACCOUNT;
 	sk->sk_write_space	= unix_write_space;
@@ -1419,9 +1417,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 		if (err)
 			goto out;
 
-		if ((test_bit(SOCK_PASSCRED, &sock->flags) ||
-		     test_bit(SOCK_PASSPIDFD, &sock->flags)) &&
-		    !READ_ONCE(unix_sk(sk)->addr)) {
+		if (unix_may_passcred(sk) && !READ_ONCE(unix_sk(sk)->addr)) {
 			err = unix_autobind(sk);
 			if (err)
 				goto out;
@@ -1539,9 +1535,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 	if (err)
 		goto out;
 
-	if ((test_bit(SOCK_PASSCRED, &sock->flags) ||
-	     test_bit(SOCK_PASSPIDFD, &sock->flags)) &&
-	    !READ_ONCE(u->addr)) {
+	if (unix_may_passcred(sk) && !READ_ONCE(u->addr)) {
 		err = unix_autobind(sk);
 		if (err)
 			goto out;
@@ -1633,10 +1627,12 @@ restart:
 	/* The way is open! Fastly set all the necessary fields... */
 
 	sock_hold(sk);
-	unix_peer(newsk)	= sk;
-	newsk->sk_state		= TCP_ESTABLISHED;
-	newsk->sk_type		= sk->sk_type;
+	unix_peer(newsk) = sk;
+	newsk->sk_state = TCP_ESTABLISHED;
+	newsk->sk_type = sk->sk_type;
+	newsk->sk_scm_recv_flags = other->sk_scm_recv_flags;
 	init_peercred(newsk);
+
 	newu = unix_sk(newsk);
 	newu->listener = other;
 	RCU_INIT_POINTER(newsk->sk_wq, &newu->peer_wq);
@@ -1717,17 +1713,6 @@ static int unix_socketpair(struct socket *socka, struct socket *sockb)
 	return 0;
 }
 
-static void unix_sock_inherit_flags(const struct socket *old,
-				    struct socket *new)
-{
-	if (test_bit(SOCK_PASSCRED, &old->flags))
-		set_bit(SOCK_PASSCRED, &new->flags);
-	if (test_bit(SOCK_PASSPIDFD, &old->flags))
-		set_bit(SOCK_PASSPIDFD, &new->flags);
-	if (test_bit(SOCK_PASSSEC, &old->flags))
-		set_bit(SOCK_PASSSEC, &new->flags);
-}
-
 static int unix_accept(struct socket *sock, struct socket *newsock,
 		       struct proto_accept_arg *arg)
 {
@@ -1764,7 +1749,6 @@ static int unix_accept(struct socket *sock, struct socket *newsock,
 	unix_state_lock(tsk);
 	unix_update_edges(unix_sk(tsk));
 	newsock->state = SS_CONNECTED;
-	unix_sock_inherit_flags(sock, newsock);
 	sock_graft(tsk, newsock);
 	unix_state_unlock(tsk);
 	return 0;
@@ -1873,7 +1857,7 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen
 {
 	int err = 0;
 
-	UNIXCB(skb).pid  = get_pid(scm->pid);
+	UNIXCB(skb).pid = get_pid(scm->pid);
 	UNIXCB(skb).uid = scm->creds.uid;
 	UNIXCB(skb).gid = scm->creds.gid;
 	UNIXCB(skb).fp = NULL;
@@ -1885,28 +1869,19 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen
 	return err;
 }
 
-static bool unix_passcred_enabled(const struct socket *sock,
-				  const struct sock *other)
-{
-	return test_bit(SOCK_PASSCRED, &sock->flags) ||
-	       test_bit(SOCK_PASSPIDFD, &sock->flags) ||
-	       !other->sk_socket ||
-	       test_bit(SOCK_PASSCRED, &other->sk_socket->flags) ||
-	       test_bit(SOCK_PASSPIDFD, &other->sk_socket->flags);
-}
-
 /*
  * Some apps rely on write() giving SCM_CREDENTIALS
  * We include credentials if source or destination socket
  * asserted SOCK_PASSCRED.
  */
-static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
-			    const struct sock *other)
+static void unix_maybe_add_creds(struct sk_buff *skb, const struct sock *sk,
+				 const struct sock *other)
 {
 	if (UNIXCB(skb).pid)
 		return;
-	if (unix_passcred_enabled(sock, other)) {
-		UNIXCB(skb).pid  = get_pid(task_tgid(current));
+
+	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);
 	}
 }
@@ -1982,9 +1957,7 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 			goto out;
 	}
 
-	if ((test_bit(SOCK_PASSCRED, &sock->flags) ||
-	     test_bit(SOCK_PASSPIDFD, &sock->flags)) &&
-	    !READ_ONCE(u->addr)) {
+	if (unix_may_passcred(sk) && !READ_ONCE(u->addr)) {
 		err = unix_autobind(sk);
 		if (err)
 			goto out;
@@ -2101,6 +2074,11 @@ restart_locked:
 		goto out_unlock;
 	}
 
+	if (UNIXCB(skb).fp && !other->sk_scm_rights) {
+		err = -EPERM;
+		goto out_unlock;
+	}
+
 	if (sk->sk_type != SOCK_SEQPACKET) {
 		err = security_unix_may_send(sk->sk_socket, other->sk_socket);
 		if (err)
@@ -2147,7 +2125,8 @@ restart_locked:
 
 	if (sock_flag(other, SOCK_RCVTSTAMP))
 		__net_timestamp(skb);
-	maybe_add_creds(skb, sock, other);
+
+	unix_maybe_add_creds(skb, sk, other);
 	scm_stat_add(other, skb);
 	skb_queue_tail(&other->sk_receive_queue, skb);
 	unix_state_unlock(other);
@@ -2175,14 +2154,14 @@ out:
 #define UNIX_SKB_FRAGS_SZ (PAGE_SIZE << get_order(32768))
 
 #if IS_ENABLED(CONFIG_AF_UNIX_OOB)
-static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other,
+static int queue_oob(struct sock *sk, struct msghdr *msg, struct sock *other,
 		     struct scm_cookie *scm, bool fds_sent)
 {
 	struct unix_sock *ousk = unix_sk(other);
 	struct sk_buff *skb;
 	int err;
 
-	skb = sock_alloc_send_skb(sock->sk, 1, msg->msg_flags & MSG_DONTWAIT, &err);
+	skb = sock_alloc_send_skb(sk, 1, msg->msg_flags & MSG_DONTWAIT, &err);
 
 	if (!skb)
 		return err;
@@ -2201,12 +2180,16 @@ static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other
 
 	if (sock_flag(other, SOCK_DEAD) ||
 	    (other->sk_shutdown & RCV_SHUTDOWN)) {
-		unix_state_unlock(other);
 		err = -EPIPE;
-		goto out;
+		goto out_unlock;
 	}
 
-	maybe_add_creds(skb, sock, other);
+	if (UNIXCB(skb).fp && !other->sk_scm_rights) {
+		err = -EPERM;
+		goto out_unlock;
+	}
+
+	unix_maybe_add_creds(skb, sk, other);
 	scm_stat_add(other, skb);
 
 	spin_lock(&other->sk_receive_queue.lock);
@@ -2219,6 +2202,8 @@ static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other
 	other->sk_data_ready(other);
 
 	return 0;
+out_unlock:
+	unix_state_unlock(other);
 out:
 	consume_skb(skb);
 	return err;
@@ -2322,7 +2307,13 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 		    (other->sk_shutdown & RCV_SHUTDOWN))
 			goto out_pipe_unlock;
 
-		maybe_add_creds(skb, sock, other);
+		if (UNIXCB(skb).fp && !other->sk_scm_rights) {
+			unix_state_unlock(other);
+			err = -EPERM;
+			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);
@@ -2332,7 +2323,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 
 #if IS_ENABLED(CONFIG_AF_UNIX_OOB)
 	if (msg->msg_flags & MSG_OOB) {
-		err = queue_oob(sock, msg, other, &scm, fds_sent);
+		err = queue_oob(sk, msg, other, &scm, fds_sent);
 		if (err)
 			goto out_err;
 		sent++;
@@ -2854,8 +2845,7 @@ unlock:
 			/* Never glue messages from different writers */
 			if (!unix_skb_scm_eq(skb, &scm))
 				break;
-		} else if (test_bit(SOCK_PASSCRED, &sock->flags) ||
-			   test_bit(SOCK_PASSPIDFD, &sock->flags)) {
+		} else if (unix_may_passcred(sk)) {
 			/* Copy credentials */
 			scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
 			unix_set_secdata(&scm, skb);