[IPV6] ADDRCONF: Allow longer lifetime on 64bit archs.

- Allow longer lifetimes (>= 0x7fffffff/HZ) on 64bit archs
  by using unsigned long.
- Shadow this arithmetic overflow workaround by introducing
  helper functions: addrconf_timeout_fixup() and
  addrconf_finite_timeout().

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

2 files changed, 53 insertions, 56 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index c3b20c5afa3e..147588f4c7c0 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -731,8 +731,13 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
                                                 onlink = -1;
 
                                         spin_lock(&ifa->lock);
-                                        lifetime = min_t(unsigned long,
-                                                         ifa->valid_lft, 0x7fffffffUL/HZ);
+
+                                        lifetime = addrconf_timeout_fixup(ifa->valid_lft, HZ);
+                                        /*
+                                         * Note: Because this address is
+                                         * not permanent, lifetime <
+                                         * LONG_MAX / HZ here.
+                                         */
                                         if (time_before(expires,
                                                         ifa->tstamp + lifetime * HZ))
                                                 expires = ifa->tstamp + lifetime * HZ;
@@ -1722,7 +1727,6 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len)
         __u32 valid_lft;
         __u32 prefered_lft;
         int addr_type;
-        unsigned long rt_expires;
         struct inet6_dev *in6_dev;
 
         pinfo = (struct prefix_info *) opt;
@@ -1764,28 +1768,23 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len)
          *      2) Configure prefixes with the auto flag set
          */
 
-        if (valid_lft == INFINITY_LIFE_TIME)
-                rt_expires = ~0UL;
-        else if (valid_lft >= 0x7FFFFFFF/HZ) {
+        if (pinfo->onlink) {
+                struct rt6_info *rt;
+                unsigned long rt_expires;
+
                 /* Avoid arithmetic overflow. Really, we could
                  * save rt_expires in seconds, likely valid_lft,
                  * but it would require division in fib gc, that it
                  * not good.
                  */
-                rt_expires = 0x7FFFFFFF - (0x7FFFFFFF % HZ);
-        } else
-                rt_expires = valid_lft * HZ;
+                if (HZ > USER_HZ)
+                        rt_expires = addrconf_timeout_fixup(valid_lft, HZ);
+                else
+                        rt_expires = addrconf_timeout_fixup(valid_lft, USER_HZ);
 
-        /*
-         * We convert this (in jiffies) to clock_t later.
-         * Avoid arithmetic overflow there as well.
-         * Overflow can happen only if HZ < USER_HZ.
-         */
-        if (HZ < USER_HZ && ~rt_expires && rt_expires > 0x7FFFFFFF / USER_HZ)
-                rt_expires = 0x7FFFFFFF / USER_HZ;
+                if (addrconf_finite_timeout(rt_expires))
+                        rt_expires *= HZ;
 
-        if (pinfo->onlink) {
-                struct rt6_info *rt;
                 rt = rt6_lookup(dev_net(dev), &pinfo->prefix, NULL,
                                 dev->ifindex, 1);
 
@@ -1794,7 +1793,7 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len)
                         if (valid_lft == 0) {
                                 ip6_del_rt(rt);
                                 rt = NULL;
-                        } else if (~rt_expires) {
+                        } else if (addrconf_finite_timeout(rt_expires)) {
                                 /* not infinity */
                                 rt->rt6i_expires = jiffies + rt_expires;
                                 rt->rt6i_flags |= RTF_EXPIRES;
@@ -1803,9 +1802,9 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len)
                                 rt->rt6i_expires = 0;
                         }
                 } else if (valid_lft) {
-                        int flags = RTF_ADDRCONF | RTF_PREFIX_RT;
                         clock_t expires = 0;
-                        if (~rt_expires) {
+                        int flags = RTF_ADDRCONF | RTF_PREFIX_RT;
+                        if (addrconf_finite_timeout(rt_expires)) {
                                 /* not infinity */
                                 flags |= RTF_EXPIRES;
                                 expires = jiffies_to_clock_t(rt_expires);
@@ -2036,6 +2035,7 @@ static int inet6_addr_add(struct net *net, int ifindex, struct in6_addr *pfx,
         int scope;
         u32 flags;
         clock_t expires;
+        unsigned long timeout;
 
         ASSERT_RTNL();
 
@@ -2055,22 +2055,23 @@ static int inet6_addr_add(struct net *net, int ifindex, struct in6_addr *pfx,
 
         scope = ipv6_addr_scope(pfx);
 
-        if (valid_lft == INFINITY_LIFE_TIME) {
-                ifa_flags |= IFA_F_PERMANENT;
-                flags = 0;
-                expires = 0;
-        } else {
-                if (valid_lft >= 0x7FFFFFFF/HZ)
-                        valid_lft = 0x7FFFFFFF/HZ;
+        timeout = addrconf_timeout_fixup(valid_lft, HZ);
+        if (addrconf_finite_timeout(timeout)) {
+                expires = jiffies_to_clock_t(timeout * HZ);
+                valid_lft = timeout;
                 flags = RTF_EXPIRES;
-                expires = jiffies_to_clock_t(valid_lft * HZ);
+        } else {
+                expires = 0;
+                flags = 0;
+                ifa_flags |= IFA_F_PERMANENT;
         }
 
-        if (prefered_lft == 0)
-                ifa_flags |= IFA_F_DEPRECATED;
-        else if ((prefered_lft >= 0x7FFFFFFF/HZ) &&
-                 (prefered_lft != INFINITY_LIFE_TIME))
-                prefered_lft = 0x7FFFFFFF/HZ;
+        timeout = addrconf_timeout_fixup(prefered_lft, HZ);
+        if (addrconf_finite_timeout(timeout)) {
+                if (timeout == 0)
+                        ifa_flags |= IFA_F_DEPRECATED;
+                prefered_lft = timeout;
+        }
 
         ifp = ipv6_add_addr(idev, pfx, plen, scope, ifa_flags);
 
@@ -3175,26 +3176,28 @@ static int inet6_addr_modify(struct inet6_ifaddr *ifp, u8 ifa_flags,
 {
         u32 flags;
         clock_t expires;
+        unsigned long timeout;
 
         if (!valid_lft || (prefered_lft > valid_lft))
                 return -EINVAL;
 
-        if (valid_lft == INFINITY_LIFE_TIME) {
-                ifa_flags |= IFA_F_PERMANENT;
-                flags = 0;
-                expires = 0;
-        } else {
-                if (valid_lft >= 0x7FFFFFFF/HZ)
-                        valid_lft = 0x7FFFFFFF/HZ;
+        timeout = addrconf_timeout_fixup(valid_lft, HZ);
+        if (addrconf_finite_timeout(timeout)) {
+                expires = jiffies_to_clock_t(timeout * HZ);
+                valid_lft = timeout;
                 flags = RTF_EXPIRES;
-                expires = jiffies_to_clock_t(valid_lft * HZ);
+        } else {
+                expires = 0;
+                flags = 0;
+                ifa_flags |= IFA_F_PERMANENT;
         }
 
-        if (prefered_lft == 0)
-                ifa_flags |= IFA_F_DEPRECATED;
-        else if ((prefered_lft >= 0x7FFFFFFF/HZ) &&
-                 (prefered_lft != INFINITY_LIFE_TIME))
-                prefered_lft = 0x7FFFFFFF/HZ;
+        timeout = addrconf_timeout_fixup(prefered_lft, HZ);
+        if (addrconf_finite_timeout(timeout)) {
+                if (timeout == 0)
+                        ifa_flags |= IFA_F_DEPRECATED;
+                prefered_lft = timeout;
+        }
 
         spin_lock_bh(&ifp->lock);
         ifp->flags = (ifp->flags & ~(IFA_F_DEPRECATED | IFA_F_PERMANENT | IFA_F_NODAD | IFA_F_HOMEADDRESS)) | ifa_flags;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 48534c6c0735..220cffe9e63b 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -446,7 +446,7 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
         struct route_info *rinfo = (struct route_info *) opt;
         struct in6_addr prefix_buf, *prefix;
         unsigned int pref;
-        u32 lifetime;
+        unsigned long lifetime;
         struct rt6_info *rt;
 
         if (len < sizeof(struct route_info)) {
@@ -472,13 +472,7 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
         if (pref == ICMPV6_ROUTER_PREF_INVALID)
                 pref = ICMPV6_ROUTER_PREF_MEDIUM;
 
-        lifetime = ntohl(rinfo->lifetime);
-        if (lifetime == 0xffffffff) {
-                /* infinity */
-        } else if (lifetime > 0x7fffffff/HZ - 1) {
-                /* Avoid arithmetic overflow */
-                lifetime = 0x7fffffff/HZ - 1;
-        }
+        lifetime = addrconf_timeout_fixup(ntohl(rinfo->lifetime), HZ);
 
         if (rinfo->length == 3)
                 prefix = (struct in6_addr *)rinfo->prefix;
@@ -506,7 +500,7 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
                                  (rt->rt6i_flags & ~RTF_PREF_MASK) | RTF_PREF(pref);
 
         if (rt) {
-                if (lifetime == 0xffffffff) {
+                if (!addrconf_finite_timeout(lifetime)) {
                         rt->rt6i_flags &= ~RTF_EXPIRES;
                 } else {
                         rt->rt6i_expires = jiffies + HZ * lifetime;