Merge branch 'sock-lockdep-tightening'

Hannes Frederic Sowa says:

====================
sock: lockdep tightening

First patch is from Eric Dumazet and improves lockdep accuracy for
socket locks. After that, second patch introduces lockdep_sock_is_held
and uses it. Final patch reverts and reworks the lockdep fix from Daniel
in the filter code, as we now have tighter lockdep support.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tun.c

@@ -622,8 +622,9 @@ static int tun_attach(struct tun_struct *tun, struct file *file, bool skip_filte
 
 	/* Re-attach the filter to persist device */
 	if (!skip_filter && (tun->filter_attached == true)) {
-		err = __sk_attach_filter(&tun->fprog, tfile->socket.sk,
-					 lockdep_rtnl_is_held());
+		lock_sock(tfile->socket.sk);
+		err = sk_attach_filter(&tun->fprog, tfile->socket.sk);
+		release_sock(tfile->socket.sk);
 		if (!err)
 			goto out;
 	}
@@ -1824,7 +1825,9 @@ static void tun_detach_filter(struct tun_struct *tun, int n)
 
 	for (i = 0; i < n; i++) {
 		tfile = rtnl_dereference(tun->tfiles[i]);
-		__sk_detach_filter(tfile->socket.sk, lockdep_rtnl_is_held());
+		lock_sock(tfile->socket.sk);
+		sk_detach_filter(tfile->socket.sk);
+		release_sock(tfile->socket.sk);
 	}
 
 	tun->filter_attached = false;
@@ -1837,8 +1840,9 @@ static int tun_attach_filter(struct tun_struct *tun)
 
 	for (i = 0; i < tun->numqueues; i++) {
 		tfile = rtnl_dereference(tun->tfiles[i]);
-		ret = __sk_attach_filter(&tun->fprog, tfile->socket.sk,
-					 lockdep_rtnl_is_held());
+		lock_sock(tfile->socket.sk);
+		ret = sk_attach_filter(&tun->fprog, tfile->socket.sk);
+		release_sock(tfile->socket.sk);
 		if (ret) {
 			tun_detach_filter(tun, i);
 			return ret;

include/linux/filter.h

@@ -465,14 +465,10 @@ int bpf_prog_create_from_user(struct bpf_prog **pfp, struct sock_fprog *fprog,
 void bpf_prog_destroy(struct bpf_prog *fp);
 
 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
-int __sk_attach_filter(struct sock_fprog *fprog, struct sock *sk,
-		       bool locked);
 int sk_attach_bpf(u32 ufd, struct sock *sk);
 int sk_reuseport_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 int sk_reuseport_attach_bpf(u32 ufd, struct sock *sk);
 int sk_detach_filter(struct sock *sk);
-int __sk_detach_filter(struct sock *sk, bool locked);
-
 int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
 		  unsigned int len);
 

include/net/sock.h

@@ -1333,7 +1333,12 @@ static inline void sk_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
 
 static inline void sock_release_ownership(struct sock *sk)
 {
-	sk->sk_lock.owned = 0;
+	if (sk->sk_lock.owned) {
+		sk->sk_lock.owned = 0;
+
+		/* The sk_lock has mutex_unlock() semantics: */
+		mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
+	}
 }
 
 /*
@@ -1355,6 +1360,14 @@ do {									\
 	lockdep_init_map(&(sk)->sk_lock.dep_map, (name), (key), 0);	\
 } while (0)
 
+static bool lockdep_sock_is_held(const struct sock *csk)
+{
+	struct sock *sk = (struct sock *)csk;
+
+	return lockdep_is_held(&sk->sk_lock) ||
+	       lockdep_is_held(&sk->sk_lock.slock);
+}
+
 void lock_sock_nested(struct sock *sk, int subclass);
 
 static inline void lock_sock(struct sock *sk)
@@ -1593,8 +1606,8 @@ static inline void sk_rethink_txhash(struct sock *sk)
 static inline struct dst_entry *
 __sk_dst_get(struct sock *sk)
 {
-	return rcu_dereference_check(sk->sk_dst_cache, sock_owned_by_user(sk) ||
-						       lockdep_is_held(&sk->sk_lock.slock));
+	return rcu_dereference_check(sk->sk_dst_cache,
+				     lockdep_sock_is_held(sk));
 }
 
 static inline struct dst_entry *

net/core/filter.c

@@ -1149,8 +1149,7 @@ void bpf_prog_destroy(struct bpf_prog *fp)
 }
 EXPORT_SYMBOL_GPL(bpf_prog_destroy);
 
-static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk,
-			    bool locked)
+static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk)
 {
 	struct sk_filter *fp, *old_fp;
 
@@ -1166,8 +1165,10 @@ static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk,
 		return -ENOMEM;
 	}
 
-	old_fp = rcu_dereference_protected(sk->sk_filter, locked);
+	old_fp = rcu_dereference_protected(sk->sk_filter,
+					   lockdep_sock_is_held(sk));
 	rcu_assign_pointer(sk->sk_filter, fp);
+
 	if (old_fp)
 		sk_filter_uncharge(sk, old_fp);
 
@@ -1246,29 +1247,23 @@ struct bpf_prog *__get_filter(struct sock_fprog *fprog, struct sock *sk)
  * occurs or there is insufficient memory for the filter a negative
  * errno code is returned. On success the return is zero.
  */
-int __sk_attach_filter(struct sock_fprog *fprog, struct sock *sk,
-		       bool locked)
+int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 {
 	struct bpf_prog *prog = __get_filter(fprog, sk);
 	int err;
 
 	if (IS_ERR(prog))
 		return PTR_ERR(prog);
 
-	err = __sk_attach_prog(prog, sk, locked);
+	err = __sk_attach_prog(prog, sk);
 	if (err < 0) {
 		__bpf_prog_release(prog);
 		return err;
 	}
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(__sk_attach_filter);
-
-int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
-{
-	return __sk_attach_filter(fprog, sk, sock_owned_by_user(sk));
-}
+EXPORT_SYMBOL_GPL(sk_attach_filter);
 
 int sk_reuseport_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 {
@@ -1314,7 +1309,7 @@ int sk_attach_bpf(u32 ufd, struct sock *sk)
 	if (IS_ERR(prog))
 		return PTR_ERR(prog);
 
-	err = __sk_attach_prog(prog, sk, sock_owned_by_user(sk));
+	err = __sk_attach_prog(prog, sk);
 	if (err < 0) {
 		bpf_prog_put(prog);
 		return err;
@@ -2255,15 +2250,16 @@ static int __init register_sk_filter_ops(void)
 }
 late_initcall(register_sk_filter_ops);
 
-int __sk_detach_filter(struct sock *sk, bool locked)
+int sk_detach_filter(struct sock *sk)
 {
 	int ret = -ENOENT;
 	struct sk_filter *filter;
 
 	if (sock_flag(sk, SOCK_FILTER_LOCKED))
 		return -EPERM;
 
-	filter = rcu_dereference_protected(sk->sk_filter, locked);
+	filter = rcu_dereference_protected(sk->sk_filter,
+					   lockdep_sock_is_held(sk));
 	if (filter) {
 		RCU_INIT_POINTER(sk->sk_filter, NULL);
 		sk_filter_uncharge(sk, filter);
@@ -2272,12 +2268,7 @@ int __sk_detach_filter(struct sock *sk, bool locked)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(__sk_detach_filter);
-
-int sk_detach_filter(struct sock *sk)
-{
-	return __sk_detach_filter(sk, sock_owned_by_user(sk));
-}
+EXPORT_SYMBOL_GPL(sk_detach_filter);
 
 int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf,
 		  unsigned int len)
@@ -2288,7 +2279,7 @@ int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf,
 
 	lock_sock(sk);
 	filter = rcu_dereference_protected(sk->sk_filter,
-					   sock_owned_by_user(sk));
+					   lockdep_sock_is_held(sk));
 	if (!filter)
 		goto out;
 

net/core/sock.c

@@ -2483,11 +2483,6 @@ EXPORT_SYMBOL(lock_sock_nested);
 
 void release_sock(struct sock *sk)
 {
-	/*
-	 * The sk_lock has mutex_unlock() semantics:
-	 */
-	mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
-
 	spin_lock_bh(&sk->sk_lock.slock);
 	if (sk->sk_backlog.tail)
 		__release_sock(sk);

net/dccp/ipv4.c

@@ -62,7 +62,7 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	nexthop = daddr = usin->sin_addr.s_addr;
 
 	inet_opt = rcu_dereference_protected(inet->inet_opt,
-					     sock_owned_by_user(sk));
+					     lockdep_sock_is_held(sk));
 	if (inet_opt != NULL && inet_opt->opt.srr) {
 		if (daddr == 0)
 			return -EINVAL;

net/dccp/ipv6.c

@@ -868,7 +868,7 @@ static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 	fl6.fl6_sport = inet->inet_sport;
 	security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 
-	opt = rcu_dereference_protected(np->opt, sock_owned_by_user(sk));
+	opt = rcu_dereference_protected(np->opt, lockdep_sock_is_held(sk));
 	final_p = fl6_update_dst(&fl6, opt, &final);
 
 	dst = ip6_dst_lookup_flow(sk, &fl6, final_p);

net/ipv4/af_inet.c

@@ -1107,7 +1107,7 @@ static int inet_sk_reselect_saddr(struct sock *sk)
 	struct ip_options_rcu *inet_opt;
 
 	inet_opt = rcu_dereference_protected(inet->inet_opt,
-					     sock_owned_by_user(sk));
+					     lockdep_sock_is_held(sk));
 	if (inet_opt && inet_opt->opt.srr)
 		daddr = inet_opt->opt.faddr;
 

net/ipv4/cipso_ipv4.c

@@ -1933,7 +1933,8 @@ int cipso_v4_sock_setattr(struct sock *sk,
 
 	sk_inet = inet_sk(sk);
 
-	old = rcu_dereference_protected(sk_inet->inet_opt, sock_owned_by_user(sk));
+	old = rcu_dereference_protected(sk_inet->inet_opt,
+					lockdep_sock_is_held(sk));
 	if (sk_inet->is_icsk) {
 		sk_conn = inet_csk(sk);
 		if (old)

net/ipv4/ip_sockglue.c

@@ -642,7 +642,7 @@ static int do_ip_setsockopt(struct sock *sk, int level,
 		if (err)
 			break;
 		old = rcu_dereference_protected(inet->inet_opt,
-						sock_owned_by_user(sk));
+						lockdep_sock_is_held(sk));
 		if (inet->is_icsk) {
 			struct inet_connection_sock *icsk = inet_csk(sk);
 #if IS_ENABLED(CONFIG_IPV6)
@@ -1302,7 +1302,7 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname,
 		struct ip_options_rcu *inet_opt;
 
 		inet_opt = rcu_dereference_protected(inet->inet_opt,
-						     sock_owned_by_user(sk));
+						     lockdep_sock_is_held(sk));
 		opt->optlen = 0;
 		if (inet_opt)
 			memcpy(optbuf, &inet_opt->opt,

net/ipv4/tcp_ipv4.c

@@ -157,7 +157,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 
 	nexthop = daddr = usin->sin_addr.s_addr;
 	inet_opt = rcu_dereference_protected(inet->inet_opt,
-					     sock_owned_by_user(sk));
+					     lockdep_sock_is_held(sk));
 	if (inet_opt && inet_opt->opt.srr) {
 		if (!daddr)
 			return -EINVAL;
@@ -882,8 +882,7 @@ struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk,
 
 	/* caller either holds rcu_read_lock() or socket lock */
 	md5sig = rcu_dereference_check(tp->md5sig_info,
-				       sock_owned_by_user(sk) ||
-				       lockdep_is_held((spinlock_t *)&sk->sk_lock.slock));
+				       lockdep_sock_is_held(sk));
 	if (!md5sig)
 		return NULL;
 #if IS_ENABLED(CONFIG_IPV6)
@@ -928,8 +927,7 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 	}
 
 	md5sig = rcu_dereference_protected(tp->md5sig_info,
-					   sock_owned_by_user(sk) ||
-					   lockdep_is_held(&sk->sk_lock.slock));
+					   lockdep_sock_is_held(sk));
 	if (!md5sig) {
 		md5sig = kmalloc(sizeof(*md5sig), gfp);
 		if (!md5sig)

net/ipv6/ipv6_sockglue.c

@@ -407,7 +407,8 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 		if (optname != IPV6_RTHDR && !ns_capable(net->user_ns, CAP_NET_RAW))
 			break;
 
-		opt = rcu_dereference_protected(np->opt, sock_owned_by_user(sk));
+		opt = rcu_dereference_protected(np->opt,
+						lockdep_sock_is_held(sk));
 		opt = ipv6_renew_options(sk, opt, optname,
 					 (struct ipv6_opt_hdr __user *)optval,
 					 optlen);
@@ -1124,7 +1125,8 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
 		struct ipv6_txoptions *opt;
 
 		lock_sock(sk);
-		opt = rcu_dereference_protected(np->opt, sock_owned_by_user(sk));
+		opt = rcu_dereference_protected(np->opt,
+						lockdep_sock_is_held(sk));
 		len = ipv6_getsockopt_sticky(sk, opt, optname, optval, len);
 		release_sock(sk);
 		/* check if ipv6_getsockopt_sticky() returns err code */

net/ipv6/tcp_ipv6.c

@@ -234,7 +234,7 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 	fl6.fl6_dport = usin->sin6_port;
 	fl6.fl6_sport = inet->inet_sport;
 
-	opt = rcu_dereference_protected(np->opt, sock_owned_by_user(sk));
+	opt = rcu_dereference_protected(np->opt, lockdep_sock_is_held(sk));
 	final_p = fl6_update_dst(&fl6, opt, &final);
 
 	security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));

net/socket.c

@@ -1046,7 +1046,7 @@ static int sock_fasync(int fd, struct file *filp, int on)
 		return -EINVAL;
 
 	lock_sock(sk);
-	wq = rcu_dereference_protected(sock->wq, sock_owned_by_user(sk));
+	wq = rcu_dereference_protected(sock->wq, lockdep_sock_is_held(sk));
 	fasync_helper(fd, filp, on, &wq->fasync_list);
 
 	if (!wq->fasync_list)