inet: move inet->recverr to inet->inet_flags

IP_RECVERR socket option can now be set/get without locking the socket.

This patch potentially avoid data-races around inet->recverr.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_sock.h

@@ -230,8 +230,7 @@ struct inet_sock {
 	__u8			min_ttl;
 	__u8			mc_ttl;
 	__u8			pmtudisc;
-	__u8			recverr:1,
-				is_icsk:1,
+	__u8			is_icsk:1,
 				freebind:1,
 				hdrincl:1,
 				mc_loop:1,
@@ -270,6 +269,8 @@ enum {
 	INET_FLAGS_ORIGDSTADDR	= 6,
 	INET_FLAGS_CHECKSUM	= 7,
 	INET_FLAGS_RECVFRAGSIZE	= 8,
+
+	INET_FLAGS_RECVERR	= 9,
 };
 
 /* cmsg flags for inet */

net/dccp/ipv4.c

@@ -247,7 +247,6 @@ static int dccp_v4_err(struct sk_buff *skb, u32 info)
 	const u8 offset = iph->ihl << 2;
 	const struct dccp_hdr *dh;
 	struct dccp_sock *dp;
-	struct inet_sock *inet;
 	const int type = icmp_hdr(skb)->type;
 	const int code = icmp_hdr(skb)->code;
 	struct sock *sk;
@@ -361,8 +360,7 @@ static int dccp_v4_err(struct sk_buff *skb, u32 info)
 	 *							--ANK (980905)
 	 */
 
-	inet = inet_sk(sk);
-	if (!sock_owned_by_user(sk) && inet->recverr) {
+	if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) {
 		sk->sk_err = err;
 		sk_error_report(sk);
 	} else { /* Only an error on timeout */

net/ipv4/inet_diag.c

@@ -182,7 +182,7 @@ int inet_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb,
 	r->idiag_inode = sock_i_ino(sk);
 
 	memset(&inet_sockopt, 0, sizeof(inet_sockopt));
-	inet_sockopt.recverr	= inet->recverr;
+	inet_sockopt.recverr	= inet_test_bit(RECVERR, sk);
 	inet_sockopt.is_icsk	= inet->is_icsk;
 	inet_sockopt.freebind	= inet->freebind;
 	inet_sockopt.hdrincl	= inet->hdrincl;

net/ipv4/ip_sockglue.c

@@ -446,12 +446,11 @@ EXPORT_SYMBOL_GPL(ip_icmp_error);
 
 void ip_local_error(struct sock *sk, int err, __be32 daddr, __be16 port, u32 info)
 {
-	struct inet_sock *inet = inet_sk(sk);
 	struct sock_exterr_skb *serr;
 	struct iphdr *iph;
 	struct sk_buff *skb;
 
-	if (!inet->recverr)
+	if (!inet_test_bit(RECVERR, sk))
 		return;
 
 	skb = alloc_skb(sizeof(struct iphdr), GFP_ATOMIC);
@@ -617,9 +616,7 @@ EXPORT_SYMBOL(ip_sock_set_freebind);
 
 void ip_sock_set_recverr(struct sock *sk)
 {
-	lock_sock(sk);
-	inet_sk(sk)->recverr = true;
-	release_sock(sk);
+	inet_set_bit(RECVERR, sk);
 }
 EXPORT_SYMBOL(ip_sock_set_recverr);
 
@@ -978,6 +975,11 @@ int do_ip_setsockopt(struct sock *sk, int level, int optname,
 			return -EINVAL;
 		inet_assign_bit(RECVFRAGSIZE, sk, val);
 		return 0;
+	case IP_RECVERR:
+		inet_assign_bit(RECVERR, sk, val);
+		if (!val)
+			skb_queue_purge(&sk->sk_error_queue);
+		return 0;
 	}
 
 	err = 0;
@@ -1064,11 +1066,6 @@ int do_ip_setsockopt(struct sock *sk, int level, int optname,
 			goto e_inval;
 		inet->pmtudisc = val;
 		break;
-	case IP_RECVERR:
-		inet->recverr = !!val;
-		if (!val)
-			skb_queue_purge(&sk->sk_error_queue);
-		break;
 	case IP_RECVERR_RFC4884:
 		if (val < 0 || val > 1)
 			goto e_inval;
@@ -1575,6 +1572,9 @@ int do_ip_getsockopt(struct sock *sk, int level, int optname,
 	case IP_RECVFRAGSIZE:
 		val = inet_test_bit(RECVFRAGSIZE, sk);
 		goto copyval;
+	case IP_RECVERR:
+		val = inet_test_bit(RECVERR, sk);
+		goto copyval;
 	}
 
 	if (needs_rtnl)
@@ -1649,9 +1649,6 @@ int do_ip_getsockopt(struct sock *sk, int level, int optname,
 		}
 		break;
 	}
-	case IP_RECVERR:
-		val = inet->recverr;
-		break;
 	case IP_RECVERR_RFC4884:
 		val = inet->recverr_rfc4884;
 		break;

net/ipv4/ping.c

@@ -580,7 +580,7 @@ void ping_err(struct sk_buff *skb, int offset, u32 info)
 	 *      RFC1122: OK.  Passes ICMP errors back to application, as per
 	 *	4.1.3.3.
 	 */
-	if ((family == AF_INET && !inet_sock->recverr) ||
+	if ((family == AF_INET && !inet_test_bit(RECVERR, sk)) ||
 	    (family == AF_INET6 && !inet6_sk(sk)->recverr)) {
 		if (!harderr || sk->sk_state != TCP_ESTABLISHED)
 			goto out;

net/ipv4/raw.c

@@ -203,8 +203,9 @@ static void raw_err(struct sock *sk, struct sk_buff *skb, u32 info)
 	struct inet_sock *inet = inet_sk(sk);
 	const int type = icmp_hdr(skb)->type;
 	const int code = icmp_hdr(skb)->code;
-	int err = 0;
 	int harderr = 0;
+	bool recverr;
+	int err = 0;
 
 	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 		ipv4_sk_update_pmtu(skb, sk, info);
@@ -218,7 +219,8 @@ static void raw_err(struct sock *sk, struct sk_buff *skb, u32 info)
 	   2. Socket is connected (otherwise the error indication
 	      is useless without ip_recverr and error is hard.
 	 */
-	if (!inet->recverr && sk->sk_state != TCP_ESTABLISHED)
+	recverr = inet_test_bit(RECVERR, sk);
+	if (!recverr && sk->sk_state != TCP_ESTABLISHED)
 		return;
 
 	switch (type) {
@@ -245,7 +247,7 @@ static void raw_err(struct sock *sk, struct sk_buff *skb, u32 info)
 		}
 	}
 
-	if (inet->recverr) {
+	if (recverr) {
 		const struct iphdr *iph = (const struct iphdr *)skb->data;
 		u8 *payload = skb->data + (iph->ihl << 2);
 
@@ -254,7 +256,7 @@ static void raw_err(struct sock *sk, struct sk_buff *skb, u32 info)
 		ip_icmp_error(sk, skb, err, 0, info, payload);
 	}
 
-	if (inet->recverr || harderr) {
+	if (recverr || harderr) {
 		sk->sk_err = err;
 		sk_error_report(sk);
 	}
@@ -413,7 +415,7 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
 	kfree_skb(skb);
 error:
 	IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
-	if (err == -ENOBUFS && !inet->recverr)
+	if (err == -ENOBUFS && !inet_test_bit(RECVERR, sk))
 		err = 0;
 	return err;
 }
@@ -645,7 +647,7 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 			ip_flush_pending_frames(sk);
 		else if (!(msg->msg_flags & MSG_MORE)) {
 			err = ip_push_pending_frames(sk, &fl4);
-			if (err == -ENOBUFS && !inet->recverr)
+			if (err == -ENOBUFS && !inet_test_bit(RECVERR, sk))
 				err = 0;
 		}
 		release_sock(sk);

net/ipv4/tcp_ipv4.c

@@ -477,7 +477,6 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
 	const struct iphdr *iph = (const struct iphdr *)skb->data;
 	struct tcphdr *th = (struct tcphdr *)(skb->data + (iph->ihl << 2));
 	struct tcp_sock *tp;
-	struct inet_sock *inet;
 	const int type = icmp_hdr(skb)->type;
 	const int code = icmp_hdr(skb)->code;
 	struct sock *sk;
@@ -625,8 +624,8 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
 	 *							--ANK (980905)
 	 */
 
-	inet = inet_sk(sk);
-	if (!sock_owned_by_user(sk) && inet->recverr) {
+	if (!sock_owned_by_user(sk) &&
+	    inet_test_bit(RECVERR, sk)) {
 		WRITE_ONCE(sk->sk_err, err);
 		sk_error_report(sk);
 	} else	{ /* Only an error on timeout */

net/ipv4/udp.c

@@ -779,7 +779,7 @@ int __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
 						  (u8 *)(uh+1));
 		goto out;
 	}
-	if (!inet->recverr) {
+	if (!inet_test_bit(RECVERR, sk)) {
 		if (!harderr || sk->sk_state != TCP_ESTABLISHED)
 			goto out;
 	} else
@@ -962,7 +962,8 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
 send:
 	err = ip_send_skb(sock_net(sk), skb);
 	if (err) {
-		if (err == -ENOBUFS && !inet->recverr) {
+		if (err == -ENOBUFS &&
+		    !inet_test_bit(RECVERR, sk)) {
 			UDP_INC_STATS(sock_net(sk),
 				      UDP_MIB_SNDBUFERRORS, is_udplite);
 			err = 0;

net/sctp/input.c

@@ -581,7 +581,7 @@ static void sctp_v4_err_handle(struct sctp_transport *t, struct sk_buff *skb,
 	default:
 		return;
 	}
-	if (!sock_owned_by_user(sk) && inet_sk(sk)->recverr) {
+	if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) {
 		sk->sk_err = err;
 		sk_error_report(sk);
 	} else {  /* Only an error on timeout */