ipv6: do retries on stable privacy addresses

If a DAD conflict is detected, we want to retry privacy stable address
generation up to idgen_retries (= 3) times with a delay of idgen_delay
(= 1 second). Add the logic to addrconf_dad_failure.

By design, we don't clean up dad failed permanent addresses.

Cc: Erik Kline <ek@google.com>
Cc: Fernando Gont <fgont@si6networks.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: YOSHIFUJI Hideaki/吉藤英明 <hideaki.yoshifuji@miraclelinux.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 54 insertions, 3 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 1cc5320e510f..9b51fdb42ba9 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1710,6 +1710,7 @@ static int addrconf_dad_end(struct inet6_ifaddr *ifp)
 
 void addrconf_dad_failure(struct inet6_ifaddr *ifp)
 {
+        struct in6_addr addr;
         struct inet6_dev *idev = ifp->idev;
 
         if (addrconf_dad_end(ifp)) {
@@ -1720,9 +1721,59 @@ void addrconf_dad_failure(struct inet6_ifaddr *ifp)
         net_info_ratelimited("%s: IPv6 duplicate address %pI6c detected!\n",
                              ifp->idev->dev->name, &ifp->addr);
 
-        if (idev->cnf.accept_dad > 1 && !idev->cnf.disable_ipv6) {
-                struct in6_addr addr;
+        spin_lock_bh(&ifp->lock);
+
+        if (ifp->flags & IFA_F_STABLE_PRIVACY) {
+                int scope = ifp->scope;
+                u32 flags = ifp->flags;
+                struct in6_addr new_addr;
+                struct inet6_ifaddr *ifp2;
+                u32 valid_lft, preferred_lft;
+                int pfxlen = ifp->prefix_len;
+                const unsigned int idgen_retries = 3;
+                const unsigned int idgen_delay = 1 * HZ;
+                int retries = ifp->stable_privacy_retry + 1;
+
+                if (retries > idgen_retries) {
+                        net_info_ratelimited("%s: privacy stable address generation failed because of DAD conflicts!\n",
+                                             ifp->idev->dev->name);
+                        goto errdad;
+                }
+
+                new_addr = ifp->addr;
+                if (ipv6_generate_stable_address(&new_addr, retries,
+                                                 idev))
+                        goto errdad;
 
+                valid_lft = ifp->valid_lft;
+                preferred_lft = ifp->prefered_lft;
+
+                spin_unlock_bh(&ifp->lock);
+
+                if (idev->cnf.max_addresses &&
+                    ipv6_count_addresses(idev) >=
+                    idev->cnf.max_addresses)
+                        goto lock_errdad;
+
+                net_info_ratelimited("%s: generating new stable privacy address because of DAD conflict\n",
+                                     ifp->idev->dev->name);
+
+                ifp2 = ipv6_add_addr(idev, &new_addr, NULL, pfxlen,
+                                     scope, flags, valid_lft,
+                                     preferred_lft);
+                if (IS_ERR(ifp2))
+                        goto lock_errdad;
+
+                spin_lock_bh(&ifp2->lock);
+                ifp2->stable_privacy_retry = retries;
+                ifp2->state = INET6_IFADDR_STATE_PREDAD;
+                spin_unlock_bh(&ifp2->lock);
+
+                addrconf_mod_dad_work(ifp2, idgen_delay);
+                in6_ifa_put(ifp2);
+lock_errdad:
+                spin_lock_bh(&ifp->lock);
+        } else if (idev->cnf.accept_dad > 1 && !idev->cnf.disable_ipv6) {
                 addr.s6_addr32[0] = htonl(0xfe800000);
                 addr.s6_addr32[1] = 0;
 
@@ -1736,7 +1787,7 @@ void addrconf_dad_failure(struct inet6_ifaddr *ifp)
                 }
         }
 
-        spin_lock_bh(&ifp->lock);
+errdad:
         /* transition from _POSTDAD to _ERRDAD */
         ifp->state = INET6_IFADDR_STATE_ERRDAD;
         spin_unlock_bh(&ifp->lock);