1 files changed, 128 insertions, 63 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 3e8a04a13668..9a6ad5974dff 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -116,8 +116,7 @@
 #include <linux/freezer.h>
 #include <linux/file.h>
 #include <linux/btf_ids.h>
-
-#include "scm.h"
+#include <linux/bpf-cgroup.h>
 
 static atomic_long_t unix_nr_socks;
 static struct hlist_head bsd_socket_buckets[UNIX_HASH_SIZE / 2];
@@ -212,8 +211,6 @@ static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb)
 }
 #endif /* CONFIG_SECURITY_NETWORK */
 
-#define unix_peer(sk) (unix_sk(sk)->peer)
-
 static inline int unix_our_peer(struct sock *sk, struct sock *osk)
 {
 	return unix_peer(osk) == sk;
@@ -783,19 +780,6 @@ static int unix_seqpacket_sendmsg(struct socket *, struct msghdr *, size_t);
 static int unix_seqpacket_recvmsg(struct socket *, struct msghdr *, size_t,
 				  int);
 
-static int unix_set_peek_off(struct sock *sk, int val)
-{
-	struct unix_sock *u = unix_sk(sk);
-
-	if (mutex_lock_interruptible(&u->iolock))
-		return -EINTR;
-
-	WRITE_ONCE(sk->sk_peek_off, val);
-	mutex_unlock(&u->iolock);
-
-	return 0;
-}
-
 #ifdef CONFIG_PROC_FS
 static int unix_count_nr_fds(struct sock *sk)
 {
@@ -863,7 +847,7 @@ static const struct proto_ops unix_stream_ops = {
 	.read_skb =	unix_stream_read_skb,
 	.mmap =		sock_no_mmap,
 	.splice_read =	unix_stream_splice_read,
-	.set_peek_off =	unix_set_peek_off,
+	.set_peek_off =	sk_set_peek_off,
 	.show_fdinfo =	unix_show_fdinfo,
 };
 
@@ -887,7 +871,7 @@ static const struct proto_ops unix_dgram_ops = {
 	.read_skb =	unix_read_skb,
 	.recvmsg =	unix_dgram_recvmsg,
 	.mmap =		sock_no_mmap,
-	.set_peek_off =	unix_set_peek_off,
+	.set_peek_off =	sk_set_peek_off,
 	.show_fdinfo =	unix_show_fdinfo,
 };
 
@@ -910,7 +894,7 @@ static const struct proto_ops unix_seqpacket_ops = {
 	.sendmsg =	unix_seqpacket_sendmsg,
 	.recvmsg =	unix_seqpacket_recvmsg,
 	.mmap =		sock_no_mmap,
-	.set_peek_off =	unix_set_peek_off,
+	.set_peek_off =	sk_set_peek_off,
 	.show_fdinfo =	unix_show_fdinfo,
 };
 
@@ -994,11 +978,11 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
 	sk->sk_write_space	= unix_write_space;
 	sk->sk_max_ack_backlog	= net->unx.sysctl_max_dgram_qlen;
 	sk->sk_destruct		= unix_sock_destructor;
-	u	  = unix_sk(sk);
+	u = unix_sk(sk);
+	u->inflight = 0;
 	u->path.dentry = NULL;
 	u->path.mnt = NULL;
 	spin_lock_init(&u->lock);
-	atomic_long_set(&u->inflight, 0);
 	INIT_LIST_HEAD(&u->link);
 	mutex_init(&u->iolock); /* single task reading lock */
 	mutex_init(&u->bindlock); /* single task binding lock */
@@ -1345,13 +1329,11 @@ static void unix_state_double_lock(struct sock *sk1, struct sock *sk2)
 		unix_state_lock(sk1);
 		return;
 	}
-	if (sk1 < sk2) {
-		unix_state_lock(sk1);
-		unix_state_lock_nested(sk2);
-	} else {
-		unix_state_lock(sk2);
-		unix_state_lock_nested(sk1);
-	}
+	if (sk1 > sk2)
+		swap(sk1, sk2);
+
+	unix_state_lock(sk1);
+	unix_state_lock_nested(sk2, U_LOCK_SECOND);
 }
 
 static void unix_state_double_unlock(struct sock *sk1, struct sock *sk2)
@@ -1381,6 +1363,10 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 		if (err)
 			goto out;
 
+		err = BPF_CGROUP_RUN_PROG_UNIX_CONNECT_LOCK(sk, addr, &alen);
+		if (err)
+			goto out;
+
 		if ((test_bit(SOCK_PASSCRED, &sock->flags) ||
 		     test_bit(SOCK_PASSPIDFD, &sock->flags)) &&
 		    !unix_sk(sk)->addr) {
@@ -1490,6 +1476,10 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 	if (err)
 		goto out;
 
+	err = BPF_CGROUP_RUN_PROG_UNIX_CONNECT_LOCK(sk, uaddr, &addr_len);
+	if (err)
+		goto out;
+
 	if ((test_bit(SOCK_PASSCRED, &sock->flags) ||
 	     test_bit(SOCK_PASSPIDFD, &sock->flags)) && !u->addr) {
 		err = unix_autobind(sk);
@@ -1584,7 +1574,7 @@ restart:
 		goto out_unlock;
 	}
 
-	unix_state_lock_nested(sk);
+	unix_state_lock_nested(sk, U_LOCK_SECOND);
 
 	if (sk->sk_state != st) {
 		unix_state_unlock(sk);
@@ -1770,12 +1760,65 @@ static int unix_getname(struct socket *sock, struct sockaddr *uaddr, int peer)
 	} else {
 		err = addr->len;
 		memcpy(sunaddr, addr->name, addr->len);
+
+		if (peer)
+			BPF_CGROUP_RUN_SA_PROG(sk, uaddr, &err,
+					       CGROUP_UNIX_GETPEERNAME);
+		else
+			BPF_CGROUP_RUN_SA_PROG(sk, uaddr, &err,
+					       CGROUP_UNIX_GETSOCKNAME);
 	}
 	sock_put(sk);
 out:
 	return err;
 }
 
+/* The "user->unix_inflight" variable is protected by the garbage
+ * collection lock, and we just read it locklessly here. If you go
+ * over the limit, there might be a tiny race in actually noticing
+ * it across threads. Tough.
+ */
+static inline bool too_many_unix_fds(struct task_struct *p)
+{
+	struct user_struct *user = current_user();
+
+	if (unlikely(READ_ONCE(user->unix_inflight) > task_rlimit(p, RLIMIT_NOFILE)))
+		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
+	return false;
+}
+
+static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
+{
+	int i;
+
+	if (too_many_unix_fds(current))
+		return -ETOOMANYREFS;
+
+	/* Need to duplicate file references for the sake of garbage
+	 * collection.  Otherwise a socket in the fps might become a
+	 * candidate for GC while the skb is not yet queued.
+	 */
+	UNIXCB(skb).fp = scm_fp_dup(scm->fp);
+	if (!UNIXCB(skb).fp)
+		return -ENOMEM;
+
+	for (i = scm->fp->count - 1; i >= 0; i--)
+		unix_inflight(scm->fp->user, scm->fp->fp[i]);
+
+	return 0;
+}
+
+static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
+{
+	int i;
+
+	scm->fp = UNIXCB(skb).fp;
+	UNIXCB(skb).fp = NULL;
+
+	for (i = scm->fp->count - 1; i >= 0; i--)
+		unix_notinflight(scm->fp->user, scm->fp->fp[i]);
+}
+
 static void unix_peek_fds(struct scm_cookie *scm, struct sk_buff *skb)
 {
 	scm->fp = scm_fp_dup(UNIXCB(skb).fp);
@@ -1823,6 +1866,21 @@ static void unix_peek_fds(struct scm_cookie *scm, struct sk_buff *skb)
 	spin_unlock(&unix_gc_lock);
 }
 
+static void unix_destruct_scm(struct sk_buff *skb)
+{
+	struct scm_cookie scm;
+
+	memset(&scm, 0, sizeof(scm));
+	scm.pid  = UNIXCB(skb).pid;
+	if (UNIXCB(skb).fp)
+		unix_detach_fds(&scm, skb);
+
+	/* Alas, it calls VFS */
+	/* So fscking what? fput() had been SMP-safe since the last Summer */
+	scm_destroy(&scm);
+	sock_wfree(skb);
+}
+
 static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
 {
 	int err = 0;
@@ -1909,11 +1967,12 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 	long timeo;
 	int err;
 
-	wait_for_unix_gc();
 	err = scm_send(sock, msg, &scm, false);
 	if (err < 0)
 		return err;
 
+	wait_for_unix_gc(scm.fp);
+
 	err = -EOPNOTSUPP;
 	if (msg->msg_flags&MSG_OOB)
 		goto out;
@@ -1922,6 +1981,13 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 		err = unix_validate_addr(sunaddr, msg->msg_namelen);
 		if (err)
 			goto out;
+
+		err = BPF_CGROUP_RUN_PROG_UNIX_SENDMSG_LOCK(sk,
+							    msg->msg_name,
+							    &msg->msg_namelen,
+							    NULL);
+		if (err)
+			goto out;
 	} else {
 		sunaddr = NULL;
 		err = -ENOTCONN;
@@ -2178,11 +2244,12 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 	bool fds_sent = false;
 	int data_len;
 
-	wait_for_unix_gc();
 	err = scm_send(sock, msg, &scm, false);
 	if (err < 0)
 		return err;
 
+	wait_for_unix_gc(scm.fp);
+
 	err = -EOPNOTSUPP;
 	if (msg->msg_flags & MSG_OOB) {
 #if IS_ENABLED(CONFIG_AF_UNIX_OOB)
@@ -2390,9 +2457,14 @@ int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
 						EPOLLOUT | EPOLLWRNORM |
 						EPOLLWRBAND);
 
-	if (msg->msg_name)
+	if (msg->msg_name) {
 		unix_copy_addr(msg, skb->sk);
 
+		BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk,
+						      msg->msg_name,
+						      &msg->msg_namelen);
+	}
+
 	if (size > skb->len - skip)
 		size = skb->len - skip;
 	else if (size < skb->len - skip)
@@ -2553,15 +2625,16 @@ static int unix_stream_recv_urg(struct unix_stream_read_state *state)
 
 	if (!(state->flags & MSG_PEEK))
 		WRITE_ONCE(u->oob_skb, NULL);
-
+	else
+		skb_get(oob_skb);
 	unix_state_unlock(sk);
 
 	chunk = state->recv_actor(oob_skb, 0, chunk, state);
 
-	if (!(state->flags & MSG_PEEK)) {
+	if (!(state->flags & MSG_PEEK))
 		UNIXCB(oob_skb).consumed += 1;
-		kfree_skb(oob_skb);
-	}
+
+	consume_skb(oob_skb);
 
 	mutex_unlock(&u->iolock);
 
@@ -2590,9 +2663,13 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 					WRITE_ONCE(u->oob_skb, NULL);
 					consume_skb(skb);
 				}
-			} else if (!(flags & MSG_PEEK)) {
+			} else if (flags & MSG_PEEK) {
+				skb = NULL;
+			} else {
 				skb_unlink(skb, &sk->sk_receive_queue);
-				consume_skb(skb);
+				WRITE_ONCE(u->oob_skb, NULL);
+				if (!WARN_ON_ONCE(skb_unref(skb)))
+					kfree_skb(skb);
 				skb = skb_peek(&sk->sk_receive_queue);
 			}
 		}
@@ -2666,18 +2743,16 @@ redo:
 		last = skb = skb_peek(&sk->sk_receive_queue);
 		last_len = last ? last->len : 0;
 
+again:
 #if IS_ENABLED(CONFIG_AF_UNIX_OOB)
 		if (skb) {
 			skb = manage_oob(skb, sk, flags, copied);
-			if (!skb) {
+			if (!skb && copied) {
 				unix_state_unlock(sk);
-				if (copied)
-					break;
-				goto redo;
+				break;
 			}
 		}
 #endif
-again:
 		if (skb == NULL) {
 			if (copied >= target)
 				goto unlock;
@@ -2744,6 +2819,11 @@ unlock:
 			DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr,
 					 state->msg->msg_name);
 			unix_copy_addr(state->msg, skb->sk);
+
+			BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk,
+							      state->msg->msg_name,
+							      &state->msg->msg_namelen);
+
 			sunaddr = NULL;
 		}
 
@@ -3311,7 +3391,7 @@ static const struct seq_operations unix_seq_ops = {
 	.show   = unix_seq_show,
 };
 
-#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL)
+#ifdef CONFIG_BPF_SYSCALL
 struct bpf_unix_iter_state {
 	struct seq_net_private p;
 	unsigned int cur_sk;
@@ -3573,7 +3653,7 @@ static struct pernet_operations unix_net_ops = {
 	.exit = unix_net_exit,
 };
 
-#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
 DEFINE_BPF_ITER_FUNC(unix, struct bpf_iter_meta *meta,
 		     struct unix_sock *unix_sk, uid_t uid)
 
@@ -3673,7 +3753,7 @@ static int __init af_unix_init(void)
 	register_pernet_subsys(&unix_net_ops);
 	unix_bpf_build_proto();
 
-#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
 	bpf_iter_register();
 #endif
 
@@ -3681,20 +3761,5 @@ out:
 	return rc;
 }
 
-static void __exit af_unix_exit(void)
-{
-	sock_unregister(PF_UNIX);
-	proto_unregister(&unix_dgram_proto);
-	proto_unregister(&unix_stream_proto);
-	unregister_pernet_subsys(&unix_net_ops);
-}
-
-/* Earlier than device_initcall() so that other drivers invoking
-   request_module() don't end up in a loop when modprobe tries
-   to use a UNIX socket. But later than subsys_initcall() because
-   we depend on stuff initialised there */
+/* Later than subsys_initcall() because we depend on stuff initialised there */
 fs_initcall(af_unix_init);
-module_exit(af_unix_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_ALIAS_NETPROTO(PF_UNIX);