inet: introduce inet->inet_flags

Various inet fields are currently racy.

do_ip_setsockopt() and do_ip_getsockopt() are mostly holding
the socket lock, but some (fast) paths do not.

Use a new inet->inet_flags to hold atomic bits in the series.

Remove inet->cmsg_flags, and use instead 9 bits from inet_flags.
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

@@ -194,6 +194,7 @@ struct rtable;
  * @inet_rcv_saddr - Bound local IPv4 addr
  * @inet_dport - Destination port
  * @inet_num - Local port
+ * @inet_flags - various atomic flags
  * @inet_saddr - Sending source
  * @uc_ttl - Unicast TTL
  * @inet_sport - Source port
@@ -218,11 +219,11 @@ struct inet_sock {
 #define inet_dport		sk.__sk_common.skc_dport
 #define inet_num		sk.__sk_common.skc_num
 
+	unsigned long		inet_flags;
 	__be32			inet_saddr;
 	__s16			uc_ttl;
-	__u16			cmsg_flags;
-	struct ip_options_rcu __rcu	*inet_opt;
 	__be16			inet_sport;
+	struct ip_options_rcu __rcu	*inet_opt;
 	__u16			inet_id;
 
 	__u8			tos;
@@ -259,16 +260,48 @@ struct inet_sock {
 #define IPCORK_OPT	1	/* ip-options has been held in ipcork.opt */
 #define IPCORK_ALLFRAG	2	/* always fragment (for ipv6 for now) */
 
+enum {
+	INET_FLAGS_PKTINFO	= 0,
+	INET_FLAGS_TTL		= 1,
+	INET_FLAGS_TOS		= 2,
+	INET_FLAGS_RECVOPTS	= 3,
+	INET_FLAGS_RETOPTS	= 4,
+	INET_FLAGS_PASSSEC	= 5,
+	INET_FLAGS_ORIGDSTADDR	= 6,
+	INET_FLAGS_CHECKSUM	= 7,
+	INET_FLAGS_RECVFRAGSIZE	= 8,
+};
+
 /* cmsg flags for inet */
-#define IP_CMSG_PKTINFO		BIT(0)
-#define IP_CMSG_TTL		BIT(1)
-#define IP_CMSG_TOS		BIT(2)
-#define IP_CMSG_RECVOPTS	BIT(3)
-#define IP_CMSG_RETOPTS		BIT(4)
-#define IP_CMSG_PASSSEC		BIT(5)
-#define IP_CMSG_ORIGDSTADDR	BIT(6)
-#define IP_CMSG_CHECKSUM	BIT(7)
-#define IP_CMSG_RECVFRAGSIZE	BIT(8)
+#define IP_CMSG_PKTINFO		BIT(INET_FLAGS_PKTINFO)
+#define IP_CMSG_TTL		BIT(INET_FLAGS_TTL)
+#define IP_CMSG_TOS		BIT(INET_FLAGS_TOS)
+#define IP_CMSG_RECVOPTS	BIT(INET_FLAGS_RECVOPTS)
+#define IP_CMSG_RETOPTS		BIT(INET_FLAGS_RETOPTS)
+#define IP_CMSG_PASSSEC		BIT(INET_FLAGS_PASSSEC)
+#define IP_CMSG_ORIGDSTADDR	BIT(INET_FLAGS_ORIGDSTADDR)
+#define IP_CMSG_CHECKSUM	BIT(INET_FLAGS_CHECKSUM)
+#define IP_CMSG_RECVFRAGSIZE	BIT(INET_FLAGS_RECVFRAGSIZE)
+
+#define IP_CMSG_ALL	(IP_CMSG_PKTINFO | IP_CMSG_TTL |		\
+			 IP_CMSG_TOS | IP_CMSG_RECVOPTS |		\
+			 IP_CMSG_RETOPTS | IP_CMSG_PASSSEC |		\
+			 IP_CMSG_ORIGDSTADDR | IP_CMSG_CHECKSUM |	\
+			 IP_CMSG_RECVFRAGSIZE)
+
+static inline unsigned long inet_cmsg_flags(const struct inet_sock *inet)
+{
+	return READ_ONCE(inet->inet_flags) & IP_CMSG_ALL;
+}
+
+#define inet_test_bit(nr, sk)			\
+	test_bit(INET_FLAGS_##nr, &inet_sk(sk)->inet_flags)
+#define inet_set_bit(nr, sk)			\
+	set_bit(INET_FLAGS_##nr, &inet_sk(sk)->inet_flags)
+#define inet_clear_bit(nr, sk)			\
+	clear_bit(INET_FLAGS_##nr, &inet_sk(sk)->inet_flags)
+#define inet_assign_bit(nr, sk, val)		\
+	assign_bit(INET_FLAGS_##nr, &inet_sk(sk)->inet_flags, val)
 
 static inline bool sk_is_inet(struct sock *sk)
 {

net/ipv4/ip_sockglue.c

@@ -171,8 +171,10 @@ static void ip_cmsg_recv_dstaddr(struct msghdr *msg, struct sk_buff *skb)
 void ip_cmsg_recv_offset(struct msghdr *msg, struct sock *sk,
 			 struct sk_buff *skb, int tlen, int offset)
 {
-	struct inet_sock *inet = inet_sk(sk);
-	unsigned int flags = inet->cmsg_flags;
+	unsigned long flags = inet_cmsg_flags(inet_sk(sk));
+
+	if (!flags)
+		return;
 
 	/* Ordered by supposed usage frequency */
 	if (flags & IP_CMSG_PKTINFO) {
@@ -568,7 +570,7 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 	if (ipv4_datagram_support_cmsg(sk, skb, serr->ee.ee_origin)) {
 		sin->sin_family = AF_INET;
 		sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
-		if (inet_sk(sk)->cmsg_flags)
+		if (inet_cmsg_flags(inet_sk(sk)))
 			ip_cmsg_recv(msg, skb);
 	}
 
@@ -635,7 +637,7 @@ EXPORT_SYMBOL(ip_sock_set_mtu_discover);
 void ip_sock_set_pktinfo(struct sock *sk)
 {
 	lock_sock(sk);
-	inet_sk(sk)->cmsg_flags |= IP_CMSG_PKTINFO;
+	inet_set_bit(PKTINFO, sk);
 	release_sock(sk);
 }
 EXPORT_SYMBOL(ip_sock_set_pktinfo);
@@ -990,67 +992,43 @@ int do_ip_setsockopt(struct sock *sk, int level, int optname,
 		break;
 	}
 	case IP_PKTINFO:
-		if (val)
-			inet->cmsg_flags |= IP_CMSG_PKTINFO;
-		else
-			inet->cmsg_flags &= ~IP_CMSG_PKTINFO;
+		inet_assign_bit(PKTINFO, sk, val);
 		break;
 	case IP_RECVTTL:
-		if (val)
-			inet->cmsg_flags |=  IP_CMSG_TTL;
-		else
-			inet->cmsg_flags &= ~IP_CMSG_TTL;
+		inet_assign_bit(TTL, sk, val);
 		break;
 	case IP_RECVTOS:
-		if (val)
-			inet->cmsg_flags |=  IP_CMSG_TOS;
-		else
-			inet->cmsg_flags &= ~IP_CMSG_TOS;
+		inet_assign_bit(TOS, sk, val);
 		break;
 	case IP_RECVOPTS:
-		if (val)
-			inet->cmsg_flags |=  IP_CMSG_RECVOPTS;
-		else
-			inet->cmsg_flags &= ~IP_CMSG_RECVOPTS;
+		inet_assign_bit(RECVOPTS, sk, val);
 		break;
 	case IP_RETOPTS:
-		if (val)
-			inet->cmsg_flags |= IP_CMSG_RETOPTS;
-		else
-			inet->cmsg_flags &= ~IP_CMSG_RETOPTS;
+		inet_assign_bit(RETOPTS, sk, val);
 		break;
 	case IP_PASSSEC:
-		if (val)
-			inet->cmsg_flags |= IP_CMSG_PASSSEC;
-		else
-			inet->cmsg_flags &= ~IP_CMSG_PASSSEC;
+		inet_assign_bit(PASSSEC, sk, val);
 		break;
 	case IP_RECVORIGDSTADDR:
-		if (val)
-			inet->cmsg_flags |= IP_CMSG_ORIGDSTADDR;
-		else
-			inet->cmsg_flags &= ~IP_CMSG_ORIGDSTADDR;
+		inet_assign_bit(ORIGDSTADDR, sk, val);
 		break;
 	case IP_CHECKSUM:
 		if (val) {
-			if (!(inet->cmsg_flags & IP_CMSG_CHECKSUM)) {
+			if (!(inet_test_bit(CHECKSUM, sk))) {
 				inet_inc_convert_csum(sk);
-				inet->cmsg_flags |= IP_CMSG_CHECKSUM;
+				inet_set_bit(CHECKSUM, sk);
 			}
 		} else {
-			if (inet->cmsg_flags & IP_CMSG_CHECKSUM) {
+			if (inet_test_bit(CHECKSUM, sk)) {
 				inet_dec_convert_csum(sk);
-				inet->cmsg_flags &= ~IP_CMSG_CHECKSUM;
+				inet_clear_bit(CHECKSUM, sk);
 			}
 		}
 		break;
 	case IP_RECVFRAGSIZE:
 		if (sk->sk_type != SOCK_RAW && sk->sk_type != SOCK_DGRAM)
 			goto e_inval;
-		if (val)
-			inet->cmsg_flags |= IP_CMSG_RECVFRAGSIZE;
-		else
-			inet->cmsg_flags &= ~IP_CMSG_RECVFRAGSIZE;
+		inet_assign_bit(RECVFRAGSIZE, sk, val);
 		break;
 	case IP_TOS:	/* This sets both TOS and Precedence */
 		__ip_sock_set_tos(sk, val);
@@ -1415,7 +1393,7 @@ int do_ip_setsockopt(struct sock *sk, int level, int optname,
 void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
 {
 	struct in_pktinfo *pktinfo = PKTINFO_SKB_CB(skb);
-	bool prepare = (inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO) ||
+	bool prepare = inet_test_bit(PKTINFO, sk) ||
 		       ipv6_sk_rxinfo(sk);
 
 	if (prepare && skb_rtable(skb)) {
@@ -1601,31 +1579,31 @@ int do_ip_getsockopt(struct sock *sk, int level, int optname,
 		return 0;
 	}
 	case IP_PKTINFO:
-		val = (inet->cmsg_flags & IP_CMSG_PKTINFO) != 0;
+		val = inet_test_bit(PKTINFO, sk);
 		break;
 	case IP_RECVTTL:
-		val = (inet->cmsg_flags & IP_CMSG_TTL) != 0;
+		val = inet_test_bit(TTL, sk);
 		break;
 	case IP_RECVTOS:
-		val = (inet->cmsg_flags & IP_CMSG_TOS) != 0;
+		val = inet_test_bit(TOS, sk);
 		break;
 	case IP_RECVOPTS:
-		val = (inet->cmsg_flags & IP_CMSG_RECVOPTS) != 0;
+		val = inet_test_bit(RECVOPTS, sk);
 		break;
 	case IP_RETOPTS:
-		val = (inet->cmsg_flags & IP_CMSG_RETOPTS) != 0;
+		val = inet_test_bit(RETOPTS, sk);
 		break;
 	case IP_PASSSEC:
-		val = (inet->cmsg_flags & IP_CMSG_PASSSEC) != 0;
+		val = inet_test_bit(PASSSEC, sk);
 		break;
 	case IP_RECVORIGDSTADDR:
-		val = (inet->cmsg_flags & IP_CMSG_ORIGDSTADDR) != 0;
+		val = inet_test_bit(ORIGDSTADDR, sk);
 		break;
 	case IP_CHECKSUM:
-		val = (inet->cmsg_flags & IP_CMSG_CHECKSUM) != 0;
+		val = inet_test_bit(CHECKSUM, sk);
 		break;
 	case IP_RECVFRAGSIZE:
-		val = (inet->cmsg_flags & IP_CMSG_RECVFRAGSIZE) != 0;
+		val = inet_test_bit(RECVFRAGSIZE, sk);
 		break;
 	case IP_TOS:
 		val = inet->tos;
@@ -1737,7 +1715,7 @@ int do_ip_getsockopt(struct sock *sk, int level, int optname,
 		msg.msg_controllen = len;
 		msg.msg_flags = in_compat_syscall() ? MSG_CMSG_COMPAT : 0;
 
-		if (inet->cmsg_flags & IP_CMSG_PKTINFO) {
+		if (inet_test_bit(PKTINFO, sk)) {
 			struct in_pktinfo info;
 
 			info.ipi_addr.s_addr = inet->inet_rcv_saddr;
@@ -1745,11 +1723,11 @@ int do_ip_getsockopt(struct sock *sk, int level, int optname,
 			info.ipi_ifindex = inet->mc_index;
 			put_cmsg(&msg, SOL_IP, IP_PKTINFO, sizeof(info), &info);
 		}
-		if (inet->cmsg_flags & IP_CMSG_TTL) {
+		if (inet_test_bit(TTL, sk)) {
 			int hlim = inet->mc_ttl;
 			put_cmsg(&msg, SOL_IP, IP_TTL, sizeof(hlim), &hlim);
 		}
-		if (inet->cmsg_flags & IP_CMSG_TOS) {
+		if (inet_test_bit(TOS, sk)) {
 			int tos = inet->rcv_tos;
 			put_cmsg(&msg, SOL_IP, IP_TOS, sizeof(tos), &tos);
 		}

net/ipv4/ping.c

@@ -894,7 +894,7 @@ int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags,
 			*addr_len = sizeof(*sin);
 		}
 
-		if (isk->cmsg_flags)
+		if (inet_cmsg_flags(isk))
 			ip_cmsg_recv(msg, skb);
 
 #if IS_ENABLED(CONFIG_IPV6)
@@ -921,7 +921,8 @@ int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags,
 		if (skb->protocol == htons(ETH_P_IPV6) &&
 		    inet6_sk(sk)->rxopt.all)
 			pingv6_ops.ip6_datagram_recv_specific_ctl(sk, msg, skb);
-		else if (skb->protocol == htons(ETH_P_IP) && isk->cmsg_flags)
+		else if (skb->protocol == htons(ETH_P_IP) &&
+			 inet_cmsg_flags(isk))
 			ip_cmsg_recv(msg, skb);
 #endif
 	} else {

net/ipv4/raw.c

@@ -767,7 +767,7 @@ static int raw_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
 		*addr_len = sizeof(*sin);
 	}
-	if (inet->cmsg_flags)
+	if (inet_cmsg_flags(inet))
 		ip_cmsg_recv(msg, skb);
 	if (flags & MSG_TRUNC)
 		copied = skb->len;

net/ipv4/udp.c

@@ -1870,7 +1870,7 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags,
 	if (udp_sk(sk)->gro_enabled)
 		udp_cmsg_recv(msg, sk, skb);
 
-	if (inet->cmsg_flags)
+	if (inet_cmsg_flags(inet))
 		ip_cmsg_recv_offset(msg, sk, skb, sizeof(struct udphdr), off);
 
 	err = copied;

net/ipv6/datagram.c

@@ -524,7 +524,7 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 		} else {
 			ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr,
 					       &sin->sin6_addr);
-			if (inet_sk(sk)->cmsg_flags)
+			if (inet_cmsg_flags(inet_sk(sk)))
 				ip_cmsg_recv(msg, skb);
 		}
 	}

net/ipv6/udp.c

@@ -420,7 +420,7 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		ip6_datagram_recv_common_ctl(sk, msg, skb);
 
 	if (is_udp4) {
-		if (inet->cmsg_flags)
+		if (inet_cmsg_flags(inet))
 			ip_cmsg_recv_offset(msg, sk, skb,
 					    sizeof(struct udphdr), off);
 	} else {

net/l2tp/l2tp_ip.c

@@ -552,7 +552,7 @@ static int l2tp_ip_recvmsg(struct sock *sk, struct msghdr *msg,
 		memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
 		*addr_len = sizeof(*sin);
 	}
-	if (inet->cmsg_flags)
+	if (inet_cmsg_flags(inet))
 		ip_cmsg_recv(msg, skb);
 	if (flags & MSG_TRUNC)
 		copied = skb->len;