[PATCH net-next 11/13] ipv6/addrconf: annotate data-races around devconf fields (I)

[Eric Dumazet <edumazet@google.com>]

Annotate lockless reads and writes on following devconf fields:

- regen_min_advance
- regen_max_retry
- dad_transmits
- use_tempaddr
- max_addresses
- max_desync_factor
- temp_valid_lft
- rtr_solicits
- rtr_solicit_max_interval
- rtr_solicit_interval
- rtr_solicit_delay
- enhanced_dad
- accept_redirects

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv6/addrconf.c | 67 +++++++++++++++++++++++++--------------------
 net/ipv6/route.c    |  3 +-
 2 files changed, 39 insertions(+), 31 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 8ba024f227b43fcba11fbfac1f3a9691841efcbf..b2cd4827c06465cd366814c1305ea9cabf5b1c37 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1359,11 +1359,12 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
 	in6_ifa_put(ifp);
 }
 
-static unsigned long ipv6_get_regen_advance(struct inet6_dev *idev)
+static unsigned long ipv6_get_regen_advance(const struct inet6_dev *idev)
 {
-	return idev->cnf.regen_min_advance + idev->cnf.regen_max_retry *
-			idev->cnf.dad_transmits *
-			max(NEIGH_VAR(idev->nd_parms, RETRANS_TIME), HZ/100) / HZ;
+	return READ_ONCE(idev->cnf.regen_min_advance) +
+		READ_ONCE(idev->cnf.regen_max_retry) *
+		READ_ONCE(idev->cnf.dad_transmits) *
+		max(NEIGH_VAR(idev->nd_parms, RETRANS_TIME), HZ/100) / HZ;
 }
 
 static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, bool block)
@@ -1384,7 +1385,7 @@ static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, bool block)
 
 retry:
 	in6_dev_hold(idev);
-	if (idev->cnf.use_tempaddr <= 0) {
+	if (READ_ONCE(idev->cnf.use_tempaddr) <= 0) {
 		write_unlock_bh(&idev->lock);
 		pr_info("%s: use_tempaddr is disabled\n", __func__);
 		in6_dev_put(idev);
@@ -1392,8 +1393,8 @@ static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, bool block)
 		goto out;
 	}
 	spin_lock_bh(&ifp->lock);
-	if (ifp->regen_count++ >= idev->cnf.regen_max_retry) {
-		idev->cnf.use_tempaddr = -1;	/*XXX*/
+	if (ifp->regen_count++ >= READ_ONCE(idev->cnf.regen_max_retry)) {
+		WRITE_ONCE(idev->cnf.use_tempaddr, -1);	/*XXX*/
 		spin_unlock_bh(&ifp->lock);
 		write_unlock_bh(&idev->lock);
 		pr_warn("%s: regeneration time exceeded - disabled temporary address support\n",
@@ -1415,7 +1416,7 @@ static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, bool block)
 	 */
 	cnf_temp_preferred_lft = READ_ONCE(idev->cnf.temp_prefered_lft);
 	max_desync_factor = min_t(long,
-				  idev->cnf.max_desync_factor,
+				  READ_ONCE(idev->cnf.max_desync_factor),
 				  cnf_temp_preferred_lft - regen_advance);
 
 	if (unlikely(idev->desync_factor > max_desync_factor)) {
@@ -1432,7 +1433,7 @@ static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, bool block)
 
 	memset(&cfg, 0, sizeof(cfg));
 	cfg.valid_lft = min_t(__u32, ifp->valid_lft,
-			      idev->cnf.temp_valid_lft + age);
+			      READ_ONCE(idev->cnf.temp_valid_lft) + age);
 	cfg.preferred_lft = cnf_temp_preferred_lft + age - idev->desync_factor;
 	cfg.preferred_lft = min_t(__u32, if_public_preferred_lft, cfg.preferred_lft);
 	cfg.preferred_lft = min_t(__u32, cfg.valid_lft, cfg.preferred_lft);
@@ -1685,7 +1686,7 @@ static int ipv6_get_saddr_eval(struct net *net,
 		 */
 		int preftmp = dst->prefs & (IPV6_PREFER_SRC_PUBLIC|IPV6_PREFER_SRC_TMP) ?
 				!!(dst->prefs & IPV6_PREFER_SRC_TMP) :
-				score->ifa->idev->cnf.use_tempaddr >= 2;
+				READ_ONCE(score->ifa->idev->cnf.use_tempaddr) >= 2;
 		ret = (!(score->ifa->flags & IFA_F_TEMPORARY)) ^ preftmp;
 		break;
 	    }
@@ -2168,6 +2169,7 @@ void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp)
 {
 	struct inet6_dev *idev = ifp->idev;
 	struct net *net = dev_net(idev->dev);
+	int max_addresses;
 
 	if (addrconf_dad_end(ifp)) {
 		in6_ifa_put(ifp);
@@ -2205,9 +2207,9 @@ void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp)
 
 		spin_unlock_bh(&ifp->lock);
 
-		if (idev->cnf.max_addresses &&
-		    ipv6_count_addresses(idev) >=
-		    idev->cnf.max_addresses)
+		max_addresses = READ_ONCE(idev->cnf.max_addresses);
+		if (max_addresses &&
+		    ipv6_count_addresses(idev) >= max_addresses)
 			goto lock_errdad;
 
 		net_info_ratelimited("%s: generating new stable privacy address because of DAD conflict\n",
@@ -2604,11 +2606,11 @@ static void manage_tempaddrs(struct inet6_dev *idev,
 		 * (TEMP_PREFERRED_LIFETIME - DESYNC_FACTOR), respectively.
 		 */
 		age = (now - ift->cstamp) / HZ;
-		max_valid = idev->cnf.temp_valid_lft - age;
+		max_valid = READ_ONCE(idev->cnf.temp_valid_lft) - age;
 		if (max_valid < 0)
 			max_valid = 0;
 
-		max_prefered = idev->cnf.temp_prefered_lft -
+		max_prefered = READ_ONCE(idev->cnf.temp_prefered_lft) -
 			       idev->desync_factor - age;
 		if (max_prefered < 0)
 			max_prefered = 0;
@@ -2641,7 +2643,7 @@ static void manage_tempaddrs(struct inet6_dev *idev,
 	if (list_empty(&idev->tempaddr_list) && (valid_lft || prefered_lft))
 		create = true;
 
-	if (create && idev->cnf.use_tempaddr > 0) {
+	if (create && READ_ONCE(idev->cnf.use_tempaddr) > 0) {
 		/* When a new public address is created as described
 		 * in [ADDRCONF], also create a new temporary address.
 		 */
@@ -2669,7 +2671,7 @@ int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev,
 	int create = 0, update_lft = 0;
 
 	if (!ifp && valid_lft) {
-		int max_addresses = in6_dev->cnf.max_addresses;
+		int max_addresses = READ_ONCE(in6_dev->cnf.max_addresses);
 		struct ifa6_config cfg = {
 			.pfx = addr,
 			.plen = pinfo->prefix_len,
@@ -4028,6 +4030,7 @@ static void addrconf_rs_timer(struct timer_list *t)
 	struct inet6_dev *idev = from_timer(idev, t, rs_timer);
 	struct net_device *dev = idev->dev;
 	struct in6_addr lladdr;
+	int rtr_solicits;
 
 	write_lock(&idev->lock);
 	if (idev->dead || !(idev->if_flags & IF_READY))
@@ -4040,7 +4043,9 @@ static void addrconf_rs_timer(struct timer_list *t)
 	if (idev->if_flags & IF_RA_RCVD)
 		goto out;
 
-	if (idev->rs_probes++ < idev->cnf.rtr_solicits || idev->cnf.rtr_solicits < 0) {
+	rtr_solicits = READ_ONCE(idev->cnf.rtr_solicits);
+
+	if (idev->rs_probes++ < rtr_solicits || rtr_solicits < 0) {
 		write_unlock(&idev->lock);
 		if (!ipv6_get_lladdr(dev, &lladdr, IFA_F_TENTATIVE))
 			ndisc_send_rs(dev, &lladdr,
@@ -4050,11 +4055,12 @@ static void addrconf_rs_timer(struct timer_list *t)
 
 		write_lock(&idev->lock);
 		idev->rs_interval = rfc3315_s14_backoff_update(
-			idev->rs_interval, idev->cnf.rtr_solicit_max_interval);
+				idev->rs_interval,
+				READ_ONCE(idev->cnf.rtr_solicit_max_interval));
 		/* The wait after the last probe can be shorter */
 		addrconf_mod_rs_timer(idev, (idev->rs_probes ==
-					     idev->cnf.rtr_solicits) ?
-				      idev->cnf.rtr_solicit_delay :
+					     READ_ONCE(idev->cnf.rtr_solicits)) ?
+				      READ_ONCE(idev->cnf.rtr_solicit_delay) :
 				      idev->rs_interval);
 	} else {
 		/*
@@ -4075,24 +4081,25 @@ static void addrconf_rs_timer(struct timer_list *t)
  */
 static void addrconf_dad_kick(struct inet6_ifaddr *ifp)
 {
-	unsigned long rand_num;
 	struct inet6_dev *idev = ifp->idev;
+	unsigned long rand_num;
 	u64 nonce;
 
 	if (ifp->flags & IFA_F_OPTIMISTIC)
 		rand_num = 0;
 	else
-		rand_num = get_random_u32_below(idev->cnf.rtr_solicit_delay ? : 1);
+		rand_num = get_random_u32_below(
+				READ_ONCE(idev->cnf.rtr_solicit_delay) ? : 1);
 
 	nonce = 0;
-	if (idev->cnf.enhanced_dad ||
-	    dev_net(idev->dev)->ipv6.devconf_all->enhanced_dad) {
+	if (READ_ONCE(idev->cnf.enhanced_dad) ||
+	    READ_ONCE(dev_net(idev->dev)->ipv6.devconf_all->enhanced_dad)) {
 		do
 			get_random_bytes(&nonce, 6);
 		while (nonce == 0);
 	}
 	ifp->dad_nonce = nonce;
-	ifp->dad_probes = idev->cnf.dad_transmits;
+	ifp->dad_probes = READ_ONCE(idev->cnf.dad_transmits);
 	addrconf_mod_dad_work(ifp, rand_num);
 }
 
@@ -4331,7 +4338,7 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp, bool bump_id,
 	send_mld = ifp->scope == IFA_LINK && ipv6_lonely_lladdr(ifp);
 	send_rs = send_mld &&
 		  ipv6_accept_ra(ifp->idev) &&
-		  ifp->idev->cnf.rtr_solicits != 0 &&
+		  READ_ONCE(ifp->idev->cnf.rtr_solicits) != 0 &&
 		  (dev->flags & IFF_LOOPBACK) == 0 &&
 		  (dev->type != ARPHRD_TUNNEL) &&
 		  !netif_is_team_port(dev);
@@ -4366,7 +4373,7 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp, bool bump_id,
 		write_lock_bh(&ifp->idev->lock);
 		spin_lock(&ifp->lock);
 		ifp->idev->rs_interval = rfc3315_s14_backoff_init(
-			ifp->idev->cnf.rtr_solicit_interval);
+			READ_ONCE(ifp->idev->cnf.rtr_solicit_interval));
 		ifp->idev->rs_probes = 1;
 		ifp->idev->if_flags |= IF_RS_SENT;
 		addrconf_mod_rs_timer(ifp->idev, ifp->idev->rs_interval);
@@ -5914,7 +5921,7 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token,
 		return -EINVAL;
 	}
 
-	if (idev->cnf.rtr_solicits == 0) {
+	if (READ_ONCE(idev->cnf.rtr_solicits) == 0) {
 		NL_SET_ERR_MSG(extack,
 			       "Router solicitation is disabled on device");
 		return -EINVAL;
@@ -5947,7 +5954,7 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token,
 	if (update_rs) {
 		idev->if_flags |= IF_RS_SENT;
 		idev->rs_interval = rfc3315_s14_backoff_init(
-			idev->cnf.rtr_solicit_interval);
+			READ_ONCE(idev->cnf.rtr_solicit_interval));
 		idev->rs_probes = 1;
 		addrconf_mod_rs_timer(idev, idev->rs_interval);
 	}
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index a92fcac902aea9307e0c83d150e9d1c41435887f..2cecb1c5a58f679abcb368a62ed914a78f2f4b5f 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4150,7 +4150,8 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
 	in6_dev = __in6_dev_get(skb->dev);
 	if (!in6_dev)
 		return;
-	if (READ_ONCE(in6_dev->cnf.forwarding) || !in6_dev->cnf.accept_redirects)
+	if (READ_ONCE(in6_dev->cnf.forwarding) ||
+	    !READ_ONCE(in6_dev->cnf.accept_redirects))
 		return;
 
 	/* RFC2461 8.1:
-- 
2.44.0.rc1.240.g4c46232300-goog