ipv6: make inet6_fill_ifaddr() lockless

Make inet6_fill_ifaddr() lockless, and add approriate annotations
on ifa->tstamp, ifa->valid_lft, ifa->preferred_lft, ifa->ifa_proto
and ifa->rt_priority.

Also constify 2nd argument of inet6_fill_ifaddr(), inet6_fill_ifmcaddr()
and inet6_fill_ifacaddr().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index f786b65d12e43c53ed36535880f6e6d35879a44e..5864a1fc6850a74c59dd311c0017b935acaf2eff 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2728,7 +2728,7 @@ int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev,
                if (update_lft) {
                        ifp->valid_lft = valid_lft;
                        ifp->prefered_lft = prefered_lft;
-                       ifp->tstamp = now;
+                       WRITE_ONCE(ifp->tstamp, now);
                        flags = ifp->flags;
                        ifp->flags &= ~IFA_F_DEPRECATED;
                        spin_unlock_bh(&ifp->lock);
@@ -4896,13 +4896,13 @@ static int inet6_addr_modify(struct net *net, struct inet6_ifaddr *ifp,
                        IFA_F_HOMEADDRESS | IFA_F_MANAGETEMPADDR |
                        IFA_F_NOPREFIXROUTE);
        ifp->flags |= cfg->ifa_flags;
-       ifp->tstamp = jiffies;
-       ifp->valid_lft = cfg->valid_lft;
-       ifp->prefered_lft = cfg->preferred_lft;
-       ifp->ifa_proto = cfg->ifa_proto;
+       WRITE_ONCE(ifp->tstamp, jiffies);
+       WRITE_ONCE(ifp->valid_lft, cfg->valid_lft);
+       WRITE_ONCE(ifp->prefered_lft, cfg->preferred_lft);
+       WRITE_ONCE(ifp->ifa_proto, cfg->ifa_proto);
 
        if (cfg->rt_priority && cfg->rt_priority != ifp->rt_priority)
-               ifp->rt_priority = cfg->rt_priority;
+               WRITE_ONCE(ifp->rt_priority, cfg->rt_priority);
 
        if (new_peer)
                ifp->peer_addr = *cfg->peer_pfx;
@@ -5123,17 +5123,21 @@ struct inet6_fill_args {
        enum addr_type_t type;
 };
 
-static int inet6_fill_ifaddr(struct sk_buff *skb, struct inet6_ifaddr *ifa,
+static int inet6_fill_ifaddr(struct sk_buff *skb,
+                            const struct inet6_ifaddr *ifa,
                             struct inet6_fill_args *args)
 {
-       struct nlmsghdr  *nlh;
+       struct nlmsghdr *nlh;
        u32 preferred, valid;
+       u32 flags, priority;
+       u8 proto;
 
        nlh = nlmsg_put(skb, args->portid, args->seq, args->event,
                        sizeof(struct ifaddrmsg), args->flags);
        if (!nlh)
                return -EMSGSIZE;
 
+       flags = READ_ONCE(ifa->flags);
        put_ifaddrmsg(nlh, ifa->prefix_len, ifa->flags, rt_scope(ifa->scope),
                      ifa->idev->dev->ifindex);
 
@@ -5141,13 +5145,14 @@ static int inet6_fill_ifaddr(struct sk_buff *skb, struct inet6_ifaddr *ifa,
            nla_put_s32(skb, IFA_TARGET_NETNSID, args->netnsid))
                goto error;
 
-       spin_lock_bh(&ifa->lock);
-       if (!((ifa->flags&IFA_F_PERMANENT) &&
-             (ifa->prefered_lft == INFINITY_LIFE_TIME))) {
-               preferred = ifa->prefered_lft;
-               valid = ifa->valid_lft;
+       preferred = READ_ONCE(ifa->prefered_lft);
+       valid = READ_ONCE(ifa->valid_lft);
+
+       if (!((flags & IFA_F_PERMANENT) &&
+             (preferred == INFINITY_LIFE_TIME))) {
                if (preferred != INFINITY_LIFE_TIME) {
-                       long tval = (jiffies - ifa->tstamp)/HZ;
+                       long tval = (jiffies - READ_ONCE(ifa->tstamp)) / HZ;
+
                        if (preferred > tval)
                                preferred -= tval;
                        else
@@ -5163,28 +5168,29 @@ static int inet6_fill_ifaddr(struct sk_buff *skb, struct inet6_ifaddr *ifa,
                preferred = INFINITY_LIFE_TIME;
                valid = INFINITY_LIFE_TIME;
        }
-       spin_unlock_bh(&ifa->lock);
 
        if (!ipv6_addr_any(&ifa->peer_addr)) {
                if (nla_put_in6_addr(skb, IFA_LOCAL, &ifa->addr) < 0 ||
                    nla_put_in6_addr(skb, IFA_ADDRESS, &ifa->peer_addr) < 0)
                        goto error;
-       } else
+       } else {
                if (nla_put_in6_addr(skb, IFA_ADDRESS, &ifa->addr) < 0)
                        goto error;
+       }
 
-       if (ifa->rt_priority &&
-           nla_put_u32(skb, IFA_RT_PRIORITY, ifa->rt_priority))
+       priority = READ_ONCE(ifa->rt_priority);
+       if (priority && nla_put_u32(skb, IFA_RT_PRIORITY, priority))
                goto error;
 
-       if (put_cacheinfo(skb, ifa->cstamp, ifa->tstamp, preferred, valid) < 0)
+       if (put_cacheinfo(skb, ifa->cstamp, READ_ONCE(ifa->tstamp),
+                         preferred, valid) < 0)
                goto error;
 
-       if (nla_put_u32(skb, IFA_FLAGS, ifa->flags) < 0)
+       if (nla_put_u32(skb, IFA_FLAGS, flags) < 0)
                goto error;
 
-       if (ifa->ifa_proto &&
-           nla_put_u8(skb, IFA_PROTO, ifa->ifa_proto))
+       proto = READ_ONCE(ifa->ifa_proto);
+       if (proto && nla_put_u8(skb, IFA_PROTO, proto))
                goto error;
 
        nlmsg_end(skb, nlh);
@@ -5195,12 +5201,13 @@ error:
        return -EMSGSIZE;
 }
 
-static int inet6_fill_ifmcaddr(struct sk_buff *skb, struct ifmcaddr6 *ifmca,
+static int inet6_fill_ifmcaddr(struct sk_buff *skb,
+                              const struct ifmcaddr6 *ifmca,
                               struct inet6_fill_args *args)
 {
-       struct nlmsghdr  *nlh;
-       u8 scope = RT_SCOPE_UNIVERSE;
        int ifindex = ifmca->idev->dev->ifindex;
+       u8 scope = RT_SCOPE_UNIVERSE;
+       struct nlmsghdr *nlh;
 
        if (ipv6_addr_scope(&ifmca->mca_addr) & IFA_SITE)
                scope = RT_SCOPE_SITE;
@@ -5218,7 +5225,7 @@ static int inet6_fill_ifmcaddr(struct sk_buff *skb, struct ifmcaddr6 *ifmca,
 
        put_ifaddrmsg(nlh, 128, IFA_F_PERMANENT, scope, ifindex);
        if (nla_put_in6_addr(skb, IFA_MULTICAST, &ifmca->mca_addr) < 0 ||
-           put_cacheinfo(skb, ifmca->mca_cstamp, ifmca->mca_tstamp,
+           put_cacheinfo(skb, ifmca->mca_cstamp, READ_ONCE(ifmca->mca_tstamp),
                          INFINITY_LIFE_TIME, INFINITY_LIFE_TIME) < 0) {
                nlmsg_cancel(skb, nlh);
                return -EMSGSIZE;
@@ -5228,13 +5235,14 @@ static int inet6_fill_ifmcaddr(struct sk_buff *skb, struct ifmcaddr6 *ifmca,
        return 0;
 }
 
-static int inet6_fill_ifacaddr(struct sk_buff *skb, struct ifacaddr6 *ifaca,
+static int inet6_fill_ifacaddr(struct sk_buff *skb,
+                              const struct ifacaddr6 *ifaca,
                               struct inet6_fill_args *args)
 {
        struct net_device *dev = fib6_info_nh_dev(ifaca->aca_rt);
        int ifindex = dev ? dev->ifindex : 1;
-       struct nlmsghdr  *nlh;
        u8 scope = RT_SCOPE_UNIVERSE;
+       struct nlmsghdr *nlh;
 
        if (ipv6_addr_scope(&ifaca->aca_addr) & IFA_SITE)
                scope = RT_SCOPE_SITE;
@@ -5252,7 +5260,7 @@ static int inet6_fill_ifacaddr(struct sk_buff *skb, struct ifacaddr6 *ifaca,
 
        put_ifaddrmsg(nlh, 128, IFA_F_PERMANENT, scope, ifindex);
        if (nla_put_in6_addr(skb, IFA_ANYCAST, &ifaca->aca_addr) < 0 ||
-           put_cacheinfo(skb, ifaca->aca_cstamp, ifaca->aca_tstamp,
+           put_cacheinfo(skb, ifaca->aca_cstamp, READ_ONCE(ifaca->aca_tstamp),
                          INFINITY_LIFE_TIME, INFINITY_LIFE_TIME) < 0) {
                nlmsg_cancel(skb, nlh);
                return -EMSGSIZE;