net/ipv6: Cleanup exception and cache route handling

IPv6 FIB will only contain FIB entries with exception routes added to
the FIB entry. Once this transformation is complete, FIB lookups will
return a fib6_info with the lookup functions still returning a dst
based rt6_info. The current code uses rt6_info for both paths and
overloads the rt6_info variable usually called 'rt'.

This patch introduces a new 'f6i' variable name for the result of the FIB
lookup and keeps 'rt' as the dst based return variable. 'f6i' becomes a
fib6_info in a later patch which is why it is introduced as f6i now;
avoids the additional churn in the later patch.

In addition, remove RTF_CACHE and dst checks from fib6 add and delete
since they can not happen now and will never happen after the data
type flip.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index ff70266..686cdc7 100644 (file)
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -106,7 +106,6 @@ int ip6_ins_rt(struct net *net, struct rt6_info *rt);
 int ip6_del_rt(struct net *net, struct rt6_info *rt);
 
 void rt6_flush_exceptions(struct rt6_info *rt);
-int rt6_remove_exception_rt(struct rt6_info *rt);
 void rt6_age_exceptions(struct rt6_info *rt, struct fib6_gc_args *gc_args,
                        unsigned long now);
 

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 280b694..53df4a9 100644 (file)
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1074,7 +1074,7 @@ add:
 static void fib6_start_gc(struct net *net, struct rt6_info *rt)
 {
        if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
-           (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
+           (rt->rt6i_flags & RTF_EXPIRES))
                mod_timer(&net->ipv6.ip6_fib_timer,
                          jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
 }
@@ -1125,8 +1125,6 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt,
 
        if (WARN_ON_ONCE(!atomic_read(&rt->dst.__refcnt)))
                return -EINVAL;
-       if (WARN_ON_ONCE(rt->rt6i_flags & RTF_CACHE))
-               return -EINVAL;
 
        if (info->nlh) {
                if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
@@ -1650,8 +1648,6 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
 
        RT6_TRACE("fib6_del_route\n");
 
-       WARN_ON_ONCE(rt->rt6i_flags & RTF_CACHE);
-
        /* Unlink it */
        *rtp = rt->rt6_next;
        rt->rt6i_node = NULL;
@@ -1720,21 +1716,11 @@ int fib6_del(struct rt6_info *rt, struct nl_info *info)
        struct rt6_info __rcu **rtp;
        struct rt6_info __rcu **rtp_next;
 
-#if RT6_DEBUG >= 2
-       if (rt->dst.obsolete > 0) {
-               WARN_ON(fn);
-               return -ENOENT;
-       }
-#endif
        if (!fn || rt == net->ipv6.fib6_null_entry)
                return -ENOENT;
 
        WARN_ON(!(fn->fn_flags & RTN_RTINFO));
 
-       /* remove cached dst from exception table */
-       if (rt->rt6i_flags & RTF_CACHE)
-               return rt6_remove_exception_rt(rt);
-
        /*
         *      Walk the leaf entries looking for ourself
         */

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 56a854b..ad9eaec 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1013,8 +1013,8 @@ static void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
        BUG_ON(from->from);
 
        rt->rt6i_flags &= ~RTF_EXPIRES;
-       dst_hold(&from->dst);
-       rt->from = from;
+       if (dst_hold_safe(&from->dst))
+               rt->from = from;
        dst_init_metrics(&rt->dst, from->fib6_metrics->metrics, true);
        if (from->fib6_metrics != &dst_default_metrics) {
                rt->dst._metrics |= DST_METRICS_REFCOUNTED;
@@ -1097,8 +1097,9 @@ static struct rt6_info *ip6_pol_route_lookup(struct net *net,
                                             const struct sk_buff *skb,
                                             int flags)
 {
-       struct rt6_info *rt, *rt_cache;
+       struct rt6_info *f6i;
        struct fib6_node *fn;
+       struct rt6_info *rt;
 
        if (fl6->flowi6_flags & FLOWI_FLAG_SKIP_NH_OIF)
                flags &= ~RT6_LOOKUP_F_IFACE;
@@ -1106,36 +1107,36 @@ static struct rt6_info *ip6_pol_route_lookup(struct net *net,
        rcu_read_lock();
        fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
 restart:
-       rt = rcu_dereference(fn->leaf);
-       if (!rt) {
-               rt = net->ipv6.fib6_null_entry;
+       f6i = rcu_dereference(fn->leaf);
+       if (!f6i) {
+               f6i = net->ipv6.fib6_null_entry;
        } else {
-               rt = rt6_device_match(net, rt, &fl6->saddr,
+               f6i = rt6_device_match(net, f6i, &fl6->saddr,
                                      fl6->flowi6_oif, flags);
-               if (rt->rt6i_nsiblings && fl6->flowi6_oif == 0)
-                       rt = rt6_multipath_select(net, rt, fl6, fl6->flowi6_oif,
-                                                 skb, flags);
+               if (f6i->rt6i_nsiblings && fl6->flowi6_oif == 0)
+                       f6i = rt6_multipath_select(net, f6i, fl6,
+                                                  fl6->flowi6_oif, skb, flags);
        }
-       if (rt == net->ipv6.fib6_null_entry) {
+       if (f6i == net->ipv6.fib6_null_entry) {
                fn = fib6_backtrack(fn, &fl6->saddr);
                if (fn)
                        goto restart;
        }
+
        /* Search through exception table */
-       rt_cache = rt6_find_cached_rt(rt, &fl6->daddr, &fl6->saddr);
-       if (rt_cache) {
-               rt = rt_cache;
+       rt = rt6_find_cached_rt(f6i, &fl6->daddr, &fl6->saddr);
+       if (rt) {
                if (ip6_hold_safe(net, &rt, true))
                        dst_use_noref(&rt->dst, jiffies);
-       } else if (dst_hold_safe(&rt->dst)) {
-               struct rt6_info *nrt;
-
-               nrt = ip6_create_rt_rcu(rt);
-               dst_release(&rt->dst);
-               rt = nrt;
-       } else {
+       } else if (f6i == net->ipv6.fib6_null_entry) {
                rt = net->ipv6.ip6_null_entry;
                dst_hold(&rt->dst);
+       } else {
+               rt = ip6_create_rt_rcu(f6i);
+               if (!rt) {
+                       rt = net->ipv6.ip6_null_entry;
+                       dst_hold(&rt->dst);
+               }
        }
 
        rcu_read_unlock();
@@ -1218,9 +1219,6 @@ static struct rt6_info *ip6_rt_cache_alloc(struct rt6_info *ort,
         *      Clone the route.
         */
 
-       if (ort->rt6i_flags & (RTF_CACHE | RTF_PCPU))
-               ort = ort->from;
-
        rcu_read_lock();
        dev = ip6_rt_get_dev_rcu(ort);
        rt = __ip6_dst_alloc(dev_net(dev), dev, 0);
@@ -1446,11 +1444,6 @@ static int rt6_insert_exception(struct rt6_info *nrt,
        struct rt6_exception *rt6_ex;
        int err = 0;
 
-       /* ort can't be a cache or pcpu route */
-       if (ort->rt6i_flags & (RTF_CACHE | RTF_PCPU))
-               ort = ort->from;
-       WARN_ON_ONCE(ort->rt6i_flags & (RTF_CACHE | RTF_PCPU));
-
        spin_lock_bh(&rt6_exception_lock);
 
        if (ort->exception_bucket_flushed) {
@@ -1589,7 +1582,7 @@ static struct rt6_info *rt6_find_cached_rt(struct rt6_info *rt,
 }
 
 /* Remove the passed in cached rt from the hash table that contains it */
-int rt6_remove_exception_rt(struct rt6_info *rt)
+static int rt6_remove_exception_rt(struct rt6_info *rt)
 {
        struct rt6_exception_bucket *bucket;
        struct rt6_info *from = rt->from;
@@ -1854,7 +1847,8 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
                               const struct sk_buff *skb, int flags)
 {
        struct fib6_node *fn, *saved_fn;
-       struct rt6_info *rt, *rt_cache;
+       struct rt6_info *f6i;
+       struct rt6_info *rt;
        int strict = 0;
 
        strict |= flags & RT6_LOOKUP_F_IFACE;
@@ -1871,10 +1865,10 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
                oif = 0;
 
 redo_rt6_select:
-       rt = rt6_select(net, fn, oif, strict);
-       if (rt->rt6i_nsiblings)
-               rt = rt6_multipath_select(net, rt, fl6, oif, skb, strict);
-       if (rt == net->ipv6.fib6_null_entry) {
+       f6i = rt6_select(net, fn, oif, strict);
+       if (f6i->rt6i_nsiblings)
+               f6i = rt6_multipath_select(net, f6i, fl6, oif, skb, strict);
+       if (f6i == net->ipv6.fib6_null_entry) {
                fn = fib6_backtrack(fn, &fl6->saddr);
                if (fn)
                        goto redo_rt6_select;
@@ -1886,18 +1880,17 @@ redo_rt6_select:
                }
        }
 
-       /*Search through exception table */
-       rt_cache = rt6_find_cached_rt(rt, &fl6->daddr, &fl6->saddr);
-       if (rt_cache)
-               rt = rt_cache;
-
-       if (rt == net->ipv6.fib6_null_entry) {
+       if (f6i == net->ipv6.fib6_null_entry) {
                rt = net->ipv6.ip6_null_entry;
                rcu_read_unlock();
                dst_hold(&rt->dst);
                trace_fib6_table_lookup(net, rt, table, fl6);
                return rt;
-       } else if (rt->rt6i_flags & RTF_CACHE) {
+       }
+
+       /*Search through exception table */
+       rt = rt6_find_cached_rt(f6i, &fl6->daddr, &fl6->saddr);
+       if (rt) {
                if (ip6_hold_safe(net, &rt, true))
                        dst_use_noref(&rt->dst, jiffies);
 
@@ -1905,7 +1898,7 @@ redo_rt6_select:
                trace_fib6_table_lookup(net, rt, table, fl6);
                return rt;
        } else if (unlikely((fl6->flowi6_flags & FLOWI_FLAG_KNOWN_NH) &&
-                           !(rt->rt6i_flags & RTF_GATEWAY))) {
+                           !(f6i->rt6i_flags & RTF_GATEWAY))) {
                /* Create a RTF_CACHE clone which will not be
                 * owned by the fib6 tree.  It is for the special case where
                 * the daddr in the skb during the neighbor look-up is different
@@ -1914,16 +1907,16 @@ redo_rt6_select:
 
                struct rt6_info *uncached_rt;
 
-               if (ip6_hold_safe(net, &rt, true)) {
-                       dst_use_noref(&rt->dst, jiffies);
+               if (ip6_hold_safe(net, &f6i, true)) {
+                       dst_use_noref(&f6i->dst, jiffies);
                } else {
                        rcu_read_unlock();
-                       uncached_rt = rt;
+                       uncached_rt = f6i;
                        goto uncached_rt_out;
                }
                rcu_read_unlock();
 
-               uncached_rt = ip6_rt_cache_alloc(rt, &fl6->daddr, NULL);
+               uncached_rt = ip6_rt_cache_alloc(f6i, &fl6->daddr, NULL);
                dst_release(&rt->dst);
 
                if (uncached_rt) {
@@ -1946,18 +1939,18 @@ uncached_rt_out:
 
                struct rt6_info *pcpu_rt;
 
-               dst_use_noref(&rt->dst, jiffies);
+               dst_use_noref(&f6i->dst, jiffies);
                local_bh_disable();
-               pcpu_rt = rt6_get_pcpu_route(rt);
+               pcpu_rt = rt6_get_pcpu_route(f6i);
 
                if (!pcpu_rt) {
                        /* atomic_inc_not_zero() is needed when using rcu */
-                       if (atomic_inc_not_zero(&rt->rt6i_ref)) {
+                       if (atomic_inc_not_zero(&f6i->rt6i_ref)) {
                                /* No dst_hold() on rt is needed because grabbing
                                 * rt->rt6i_ref makes sure rt can't be released.
                                 */
-                               pcpu_rt = rt6_make_pcpu_route(net, rt);
-                               rt6_release(rt);
+                               pcpu_rt = rt6_make_pcpu_route(net, f6i);
+                               rt6_release(f6i);
                        } else {
                                /* rt is already removed from tree */
                                pcpu_rt = net->ipv6.ip6_null_entry;
@@ -2419,7 +2412,8 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
                                             int flags)
 {
        struct ip6rd_flowi *rdfl = (struct ip6rd_flowi *)fl6;
-       struct rt6_info *rt, *rt_cache;
+       struct rt6_info *ret = NULL, *rt_cache;
+       struct rt6_info *rt;
        struct fib6_node *fn;
 
        /* Get the "current" route for this destination and
@@ -2458,7 +2452,7 @@ restart:
                        if (rt_cache &&
                            ipv6_addr_equal(&rdfl->gateway,
                                            &rt_cache->rt6i_gateway)) {
-                               rt = rt_cache;
+                               ret = rt_cache;
                                break;
                        }
                        continue;
@@ -2469,7 +2463,7 @@ restart:
        if (!rt)
                rt = net->ipv6.fib6_null_entry;
        else if (rt->rt6i_flags & RTF_REJECT) {
-               rt = net->ipv6.ip6_null_entry;
+               ret = net->ipv6.ip6_null_entry;
                goto out;
        }
 
@@ -2480,12 +2474,15 @@ restart:
        }
 
 out:
-       ip6_hold_safe(net, &rt, true);
+       if (ret)
+               dst_hold(&ret->dst);
+       else
+               ret = ip6_create_rt_rcu(rt);
 
        rcu_read_unlock();
 
-       trace_fib6_table_lookup(net, rt, table, fl6);
-       return rt;
+       trace_fib6_table_lookup(net, ret, table, fl6);
+       return ret;
 };
 
 static struct dst_entry *ip6_route_redirect(struct net *net,
@@ -3182,6 +3179,22 @@ out_put:
        return err;
 }
 
+static int ip6_del_cached_rt(struct rt6_info *rt, struct fib6_config *cfg)
+{
+       int rc = -ESRCH;
+
+       if (cfg->fc_ifindex && rt->dst.dev->ifindex != cfg->fc_ifindex)
+               goto out;
+
+       if (cfg->fc_flags & RTF_GATEWAY &&
+           !ipv6_addr_equal(&cfg->fc_gateway, &rt->rt6i_gateway))
+               goto out;
+       if (dst_hold_safe(&rt->dst))
+               rc = rt6_remove_exception_rt(rt);
+out:
+       return rc;
+}
+
 static int ip6_route_del(struct fib6_config *cfg,
                         struct netlink_ext_ack *extack)
 {
@@ -3206,11 +3219,16 @@ static int ip6_route_del(struct fib6_config *cfg,
        if (fn) {
                for_each_fib6_node_rt_rcu(fn) {
                        if (cfg->fc_flags & RTF_CACHE) {
+                               int rc;
+
                                rt_cache = rt6_find_cached_rt(rt, &cfg->fc_dst,
                                                              &cfg->fc_src);
-                               if (!rt_cache)
-                                       continue;
-                               rt = rt_cache;
+                               if (rt_cache) {
+                                       rc = ip6_del_cached_rt(rt_cache, cfg);
+                                       if (rc != -ESRCH)
+                                               return rc;
+                               }
+                               continue;
                        }
                        if (cfg->fc_ifindex &&
                            (!rt->fib6_nh.nh_dev ||
@@ -3327,7 +3345,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
                                     NEIGH_UPDATE_F_ISROUTER)),
                     NDISC_REDIRECT, &ndopts);
 
-       nrt = ip6_rt_cache_alloc(rt, &msg->dest, NULL);
+       nrt = ip6_rt_cache_alloc(rt->from, &msg->dest, NULL);
        if (!nrt)
                goto out;