net: ipv4: provide __rcu annotation for ifa_list

ifa_list is protected by rcu, yet code doesn't reflect this.

Add the __rcu annotations and fix up all places that are now reported by
sparse.

I've done this in the same commit to not add intermediate patches that
result in new warnings.

Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 57 insertions, 31 deletions

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index b45421b2b734..ebaea05b4033 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -194,7 +194,8 @@ static void rtmsg_ifa(int event, struct in_ifaddr *, struct nlmsghdr *, u32);
 
 static BLOCKING_NOTIFIER_HEAD(inetaddr_chain);
 static BLOCKING_NOTIFIER_HEAD(inetaddr_validator_chain);
-static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
+static void inet_del_ifa(struct in_device *in_dev,
+			 struct in_ifaddr __rcu **ifap,
 			 int destroy);
 #ifdef CONFIG_SYSCTL
 static int devinet_sysctl_register(struct in_device *idev);
@@ -300,8 +301,8 @@ static void in_dev_rcu_put(struct rcu_head *head)
 
 static void inetdev_destroy(struct in_device *in_dev)
 {
-	struct in_ifaddr *ifa;
 	struct net_device *dev;
+	struct in_ifaddr *ifa;
 
 	ASSERT_RTNL();
 
@@ -311,7 +312,7 @@ static void inetdev_destroy(struct in_device *in_dev)
 
 	ip_mc_destroy_dev(in_dev);
 
-	while ((ifa = in_dev->ifa_list) != NULL) {
+	while ((ifa = rtnl_dereference(in_dev->ifa_list)) != NULL) {
 		inet_del_ifa(in_dev, &in_dev->ifa_list, 0);
 		inet_free_ifa(ifa);
 	}
@@ -342,17 +343,20 @@ int inet_addr_onlink(struct in_device *in_dev, __be32 a, __be32 b)
 	return 0;
 }
 
-static void __inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
-			 int destroy, struct nlmsghdr *nlh, u32 portid)
+static void __inet_del_ifa(struct in_device *in_dev,
+			   struct in_ifaddr __rcu **ifap,
+			   int destroy, struct nlmsghdr *nlh, u32 portid)
 {
 	struct in_ifaddr *promote = NULL;
-	struct in_ifaddr *ifa, *ifa1 = *ifap;
-	struct in_ifaddr *last_prim = in_dev->ifa_list;
+	struct in_ifaddr *ifa, *ifa1;
+	struct in_ifaddr *last_prim;
 	struct in_ifaddr *prev_prom = NULL;
 	int do_promote = IN_DEV_PROMOTE_SECONDARIES(in_dev);
 
 	ASSERT_RTNL();
 
+	ifa1 = rtnl_dereference(*ifap);
+	last_prim = rtnl_dereference(in_dev->ifa_list);
 	if (in_dev->dead)
 		goto no_promotions;
 
@@ -361,9 +365,9 @@ static void __inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
 	 **/
 
 	if (!(ifa1->ifa_flags & IFA_F_SECONDARY)) {
-		struct in_ifaddr **ifap1 = &ifa1->ifa_next;
+		struct in_ifaddr __rcu **ifap1 = &ifa1->ifa_next;
 
-		while ((ifa = *ifap1) != NULL) {
+		while ((ifa = rtnl_dereference(*ifap1)) != NULL) {
 			if (!(ifa->ifa_flags & IFA_F_SECONDARY) &&
 			    ifa1->ifa_scope <= ifa->ifa_scope)
 				last_prim = ifa;
@@ -396,7 +400,7 @@ static void __inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
 	 * and later to add them back with new prefsrc. Do this
 	 * while all addresses are on the device list.
 	 */
-	for (ifa = promote; ifa; ifa = ifa->ifa_next) {
+	for (ifa = promote; ifa; ifa = rtnl_dereference(ifa->ifa_next)) {
 		if (ifa1->ifa_mask == ifa->ifa_mask &&
 		    inet_ifa_match(ifa1->ifa_address, ifa))
 			fib_del_ifaddr(ifa, ifa1);
@@ -422,19 +426,24 @@ no_promotions:
 	blocking_notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa1);
 
 	if (promote) {
-		struct in_ifaddr *next_sec = promote->ifa_next;
+		struct in_ifaddr *next_sec;
 
+		next_sec = rtnl_dereference(promote->ifa_next);
 		if (prev_prom) {
-			prev_prom->ifa_next = promote->ifa_next;
-			promote->ifa_next = last_prim->ifa_next;
-			last_prim->ifa_next = promote;
+			struct in_ifaddr *last_sec;
+
+			last_sec = rtnl_dereference(last_prim->ifa_next);
+			rcu_assign_pointer(prev_prom->ifa_next, next_sec);
+			rcu_assign_pointer(promote->ifa_next, last_sec);
+			rcu_assign_pointer(last_prim->ifa_next, promote);
 		}
 
 		promote->ifa_flags &= ~IFA_F_SECONDARY;
 		rtmsg_ifa(RTM_NEWADDR, promote, nlh, portid);
 		blocking_notifier_call_chain(&inetaddr_chain,
 				NETDEV_UP, promote);
-		for (ifa = next_sec; ifa; ifa = ifa->ifa_next) {
+		for (ifa = next_sec; ifa;
+		     ifa = rtnl_dereference(ifa->ifa_next)) {
 			if (ifa1->ifa_mask != ifa->ifa_mask ||
 			    !inet_ifa_match(ifa1->ifa_address, ifa))
 					continue;
@@ -446,7 +455,8 @@ no_promotions:
 		inet_free_ifa(ifa1);
 }
 
-static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
+static void inet_del_ifa(struct in_device *in_dev,
+			 struct in_ifaddr __rcu **ifap,
 			 int destroy)
 {
 	__inet_del_ifa(in_dev, ifap, destroy, NULL, 0);
@@ -459,9 +469,10 @@ static DECLARE_DELAYED_WORK(check_lifetime_work, check_lifetime);
 static int __inet_insert_ifa(struct in_ifaddr *ifa, struct nlmsghdr *nlh,
 			     u32 portid, struct netlink_ext_ack *extack)
 {
+	struct in_ifaddr __rcu **last_primary, **ifap;
 	struct in_device *in_dev = ifa->ifa_dev;
-	struct in_ifaddr *ifa1, **ifap, **last_primary;
 	struct in_validator_info ivi;
+	struct in_ifaddr *ifa1;
 	int ret;
 
 	ASSERT_RTNL();
@@ -474,8 +485,10 @@ static int __inet_insert_ifa(struct in_ifaddr *ifa, struct nlmsghdr *nlh,
 	ifa->ifa_flags &= ~IFA_F_SECONDARY;
 	last_primary = &in_dev->ifa_list;
 
-	for (ifap = &in_dev->ifa_list; (ifa1 = *ifap) != NULL;
-	     ifap = &ifa1->ifa_next) {
+	ifap = &in_dev->ifa_list;
+	ifa1 = rtnl_dereference(*ifap);
+
+	while (ifa1) {
 		if (!(ifa1->ifa_flags & IFA_F_SECONDARY) &&
 		    ifa->ifa_scope <= ifa1->ifa_scope)
 			last_primary = &ifa1->ifa_next;
@@ -491,6 +504,9 @@ static int __inet_insert_ifa(struct in_ifaddr *ifa, struct nlmsghdr *nlh,
 			}
 			ifa->ifa_flags |= IFA_F_SECONDARY;
 		}
+
+		ifap = &ifa1->ifa_next;
+		ifa1 = rtnl_dereference(*ifap);
 	}
 
 	/* Allow any devices that wish to register ifaddr validtors to weigh
@@ -516,8 +532,8 @@ static int __inet_insert_ifa(struct in_ifaddr *ifa, struct nlmsghdr *nlh,
 		ifap = last_primary;
 	}
 
-	ifa->ifa_next = *ifap;
-	*ifap = ifa;
+	rcu_assign_pointer(ifa->ifa_next, *ifap);
+	rcu_assign_pointer(*ifap, ifa);
 
 	inet_hash_insert(dev_net(in_dev->dev), ifa);
 
@@ -617,10 +633,12 @@ static int inet_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
 			    struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(skb->sk);
+	struct in_ifaddr __rcu **ifap;
 	struct nlattr *tb[IFA_MAX+1];
 	struct in_device *in_dev;
 	struct ifaddrmsg *ifm;
-	struct in_ifaddr *ifa, **ifap;
+	struct in_ifaddr *ifa;
+
 	int err = -EINVAL;
 
 	ASSERT_RTNL();
@@ -637,7 +655,7 @@ static int inet_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
 		goto errout;
 	}
 
-	for (ifap = &in_dev->ifa_list; (ifa = *ifap) != NULL;
+	for (ifap = &in_dev->ifa_list; (ifa = rtnl_dereference(*ifap)) != NULL;
 	     ifap = &ifa->ifa_next) {
 		if (tb[IFA_LOCAL] &&
 		    ifa->ifa_local != nla_get_in_addr(tb[IFA_LOCAL]))
@@ -725,15 +743,20 @@ static void check_lifetime(struct work_struct *work)
 
 			if (ifa->ifa_valid_lft != INFINITY_LIFE_TIME &&
 			    age >= ifa->ifa_valid_lft) {
-				struct in_ifaddr **ifap;
-
-				for (ifap = &ifa->ifa_dev->ifa_list;
-				     *ifap != NULL; ifap = &(*ifap)->ifa_next) {
-					if (*ifap == ifa) {
+				struct in_ifaddr __rcu **ifap;
+				struct in_ifaddr *tmp;
+
+				ifap = &ifa->ifa_dev->ifa_list;
+				tmp = rtnl_dereference(*ifap);
+				while (tmp) {
+					tmp = rtnl_dereference(tmp->ifa_next);
+					if (rtnl_dereference(*ifap) == ifa) {
 						inet_del_ifa(ifa->ifa_dev,
 							     ifap, 1);
 						break;
 					}
+					ifap = &tmp->ifa_next;
+					tmp = rtnl_dereference(*ifap);
 				}
 			} else if (ifa->ifa_preferred_lft !=
 				   INFINITY_LIFE_TIME &&
@@ -977,8 +1000,8 @@ int devinet_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr)
 {
 	struct sockaddr_in sin_orig;
 	struct sockaddr_in *sin = (struct sockaddr_in *)&ifr->ifr_addr;
+	struct in_ifaddr __rcu **ifap = NULL;
 	struct in_device *in_dev;
-	struct in_ifaddr **ifap = NULL;
 	struct in_ifaddr *ifa = NULL;
 	struct net_device *dev;
 	char *colon;
@@ -1049,7 +1072,9 @@ int devinet_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr)
 			/* note: we only do this for a limited set of ioctls
 			   and only if the original address family was AF_INET.
 			   This is checked above. */
-			for (ifap = &in_dev->ifa_list; (ifa = *ifap) != NULL;
+
+			for (ifap = &in_dev->ifa_list;
+			     (ifa = rtnl_dereference(*ifap)) != NULL;
 			     ifap = &ifa->ifa_next) {
 				if (!strcmp(ifr->ifr_name, ifa->ifa_label) &&
 				    sin_orig.sin_addr.s_addr ==
@@ -1062,7 +1087,8 @@ int devinet_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr)
 		   4.3BSD-style and passed in junk so we fall back to
 		   comparing just the label */
 		if (!ifa) {
-			for (ifap = &in_dev->ifa_list; (ifa = *ifap) != NULL;
+			for (ifap = &in_dev->ifa_list;
+			     (ifa = rtnl_dereference(*ifap)) != NULL;
 			     ifap = &ifa->ifa_next)
 				if (!strcmp(ifr->ifr_name, ifa->ifa_label))
 					break;