ipmr: RCU protection for mfc_cache_array

Use RCU & RTNL protection for mfc_cache_array[]

ipmr_cache_find() is called under rcu_read_lock();

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 47 insertions, 40 deletions

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index e2db2ea616ff..cbb6dabe024f 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -577,11 +577,18 @@ static int vif_delete(struct mr_table *mrt, int vifi, int notify,
         return 0;
 }
 
-static inline void ipmr_cache_free(struct mfc_cache *c)
+static void ipmr_cache_free_rcu(struct rcu_head *head)
 {
+        struct mfc_cache *c = container_of(head, struct mfc_cache, rcu);
+
         kmem_cache_free(mrt_cachep, c);
 }
 
+static inline void ipmr_cache_free(struct mfc_cache *c)
+{
+        call_rcu(&c->rcu, ipmr_cache_free_rcu);
+}
+
 /* Destroy an unresolved cache entry, killing queued skbs
    and reporting error to netlink readers.
  */
@@ -781,6 +788,7 @@ static int vif_add(struct net *net, struct mr_table *mrt,
         return 0;
 }
 
+/* called with rcu_read_lock() */
 static struct mfc_cache *ipmr_cache_find(struct mr_table *mrt,
                                          __be32 origin,
                                          __be32 mcastgrp)
@@ -788,7 +796,7 @@ static struct mfc_cache *ipmr_cache_find(struct mr_table *mrt,
         int line = MFC_HASH(mcastgrp, origin);
         struct mfc_cache *c;
 
-        list_for_each_entry(c, &mrt->mfc_cache_array[line], list) {
+        list_for_each_entry_rcu(c, &mrt->mfc_cache_array[line], list) {
                 if (c->mfc_origin == origin && c->mfc_mcastgrp == mcastgrp)
                         return c;
         }
@@ -801,19 +809,20 @@ static struct mfc_cache *ipmr_cache_find(struct mr_table *mrt,
 static struct mfc_cache *ipmr_cache_alloc(void)
 {
         struct mfc_cache *c = kmem_cache_zalloc(mrt_cachep, GFP_KERNEL);
-        if (c == NULL)
-                return NULL;
-        c->mfc_un.res.minvif = MAXVIFS;
+
+        if (c)
+                c->mfc_un.res.minvif = MAXVIFS;
         return c;
 }
 
 static struct mfc_cache *ipmr_cache_alloc_unres(void)
 {
         struct mfc_cache *c = kmem_cache_zalloc(mrt_cachep, GFP_ATOMIC);
-        if (c == NULL)
-                return NULL;
-        skb_queue_head_init(&c->mfc_un.unres.unresolved);
-        c->mfc_un.unres.expires = jiffies + 10*HZ;
+
+        if (c) {
+                skb_queue_head_init(&c->mfc_un.unres.unresolved);
+                c->mfc_un.unres.expires = jiffies + 10*HZ;
+        }
         return c;
 }
 
@@ -1040,9 +1049,7 @@ static int ipmr_mfc_delete(struct mr_table *mrt, struct mfcctl *mfc)
         list_for_each_entry_safe(c, next, &mrt->mfc_cache_array[line], list) {
                 if (c->mfc_origin == mfc->mfcc_origin.s_addr &&
                     c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr) {
-                        write_lock_bh(&mrt_lock);
-                        list_del(&c->list);
-                        write_unlock_bh(&mrt_lock);
+                        list_del_rcu(&c->list);
 
                         ipmr_cache_free(c);
                         return 0;
@@ -1095,9 +1102,7 @@ static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
         if (!mrtsock)
                 c->mfc_flags |= MFC_STATIC;
 
-        write_lock_bh(&mrt_lock);
-        list_add(&c->list, &mrt->mfc_cache_array[line]);
-        write_unlock_bh(&mrt_lock);
+        list_add_rcu(&c->list, &mrt->mfc_cache_array[line]);
 
         /*
          *      Check to see if we resolved a queued list. If so we
@@ -1149,12 +1154,9 @@ static void mroute_clean_tables(struct mr_table *mrt)
          */
         for (i = 0; i < MFC_LINES; i++) {
                 list_for_each_entry_safe(c, next, &mrt->mfc_cache_array[i], list) {
-                        if (c->mfc_flags&MFC_STATIC)
+                        if (c->mfc_flags & MFC_STATIC)
                                 continue;
-                        write_lock_bh(&mrt_lock);
-                        list_del(&c->list);
-                        write_unlock_bh(&mrt_lock);
-
+                        list_del_rcu(&c->list);
                         ipmr_cache_free(c);
                 }
         }
@@ -1422,19 +1424,19 @@ int ipmr_ioctl(struct sock *sk, int cmd, void __user *arg)
                 if (copy_from_user(&sr, arg, sizeof(sr)))
                         return -EFAULT;
 
-                read_lock(&mrt_lock);
+                rcu_read_lock();
                 c = ipmr_cache_find(mrt, sr.src.s_addr, sr.grp.s_addr);
                 if (c) {
                         sr.pktcnt = c->mfc_un.res.pkt;
                         sr.bytecnt = c->mfc_un.res.bytes;
                         sr.wrong_if = c->mfc_un.res.wrong_if;
-                        read_unlock(&mrt_lock);
+                        rcu_read_unlock();
 
                         if (copy_to_user(arg, &sr, sizeof(sr)))
                                 return -EFAULT;
                         return 0;
                 }
-                read_unlock(&mrt_lock);
+                rcu_read_unlock();
                 return -EADDRNOTAVAIL;
         default:
                 return -ENOIOCTLCMD;
@@ -1764,7 +1766,7 @@ int ip_mr_input(struct sk_buff *skb)
                     }
         }
 
-        read_lock(&mrt_lock);
+        /* already under rcu_read_lock() */
         cache = ipmr_cache_find(mrt, ip_hdr(skb)->saddr, ip_hdr(skb)->daddr);
 
         /*
@@ -1776,13 +1778,12 @@ int ip_mr_input(struct sk_buff *skb)
                 if (local) {
                         struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
                         ip_local_deliver(skb);
-                        if (skb2 == NULL) {
-                                read_unlock(&mrt_lock);
+                        if (skb2 == NULL)
                                 return -ENOBUFS;
-                        }
                         skb = skb2;
                 }
 
+                read_lock(&mrt_lock);
                 vif = ipmr_find_vif(mrt, skb->dev);
                 if (vif >= 0) {
                         int err2 = ipmr_cache_unresolved(mrt, vif, skb);
@@ -1795,8 +1796,8 @@ int ip_mr_input(struct sk_buff *skb)
                 return -ENODEV;
         }
 
+        read_lock(&mrt_lock);
         ip_mr_forward(net, mrt, skb, cache, local);
-
         read_unlock(&mrt_lock);
 
         if (local)
@@ -1963,7 +1964,7 @@ int ipmr_get_route(struct net *net,
         if (mrt == NULL)
                 return -ENOENT;
 
-        read_lock(&mrt_lock);
+        rcu_read_lock();
         cache = ipmr_cache_find(mrt, rt->rt_src, rt->rt_dst);
 
         if (cache == NULL) {
@@ -1973,18 +1974,21 @@ int ipmr_get_route(struct net *net,
                 int vif;
 
                 if (nowait) {
-                        read_unlock(&mrt_lock);
+                        rcu_read_unlock();
                         return -EAGAIN;
                 }
 
                 dev = skb->dev;
+                read_lock(&mrt_lock);
                 if (dev == NULL || (vif = ipmr_find_vif(mrt, dev)) < 0) {
                         read_unlock(&mrt_lock);
+                        rcu_read_unlock();
                         return -ENODEV;
                 }
                 skb2 = skb_clone(skb, GFP_ATOMIC);
                 if (!skb2) {
                         read_unlock(&mrt_lock);
+                        rcu_read_unlock();
                         return -ENOMEM;
                 }
 
@@ -1997,13 +2001,16 @@ int ipmr_get_route(struct net *net,
                 iph->version = 0;
                 err = ipmr_cache_unresolved(mrt, vif, skb2);
                 read_unlock(&mrt_lock);
+                rcu_read_unlock();
                 return err;
         }
 
-        if (!nowait && (rtm->rtm_flags&RTM_F_NOTIFY))
+        read_lock(&mrt_lock);
+        if (!nowait && (rtm->rtm_flags & RTM_F_NOTIFY))
                 cache->mfc_flags |= MFC_NOTIFY;
         err = __ipmr_fill_mroute(mrt, skb, cache, rtm);
         read_unlock(&mrt_lock);
+        rcu_read_unlock();
         return err;
 }
 
@@ -2055,14 +2062,14 @@ static int ipmr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
         s_h = cb->args[1];
         s_e = cb->args[2];
 
-        read_lock(&mrt_lock);
+        rcu_read_lock();
         ipmr_for_each_table(mrt, net) {
                 if (t < s_t)
                         goto next_table;
                 if (t > s_t)
                         s_h = 0;
                 for (h = s_h; h < MFC_LINES; h++) {
-                        list_for_each_entry(mfc, &mrt->mfc_cache_array[h], list) {
+                        list_for_each_entry_rcu(mfc, &mrt->mfc_cache_array[h], list) {
                                 if (e < s_e)
                                         goto next_entry;
                                 if (ipmr_fill_mroute(mrt, skb,
@@ -2080,7 +2087,7 @@ next_table:
                 t++;
         }
 done:
-        read_unlock(&mrt_lock);
+        rcu_read_unlock();
 
         cb->args[2] = e;
         cb->args[1] = h;
@@ -2213,14 +2220,14 @@ static struct mfc_cache *ipmr_mfc_seq_idx(struct net *net,
         struct mr_table *mrt = it->mrt;
         struct mfc_cache *mfc;
 
-        read_lock(&mrt_lock);
+        rcu_read_lock();
         for (it->ct = 0; it->ct < MFC_LINES; it->ct++) {
                 it->cache = &mrt->mfc_cache_array[it->ct];
-                list_for_each_entry(mfc, it->cache, list)
+                list_for_each_entry_rcu(mfc, it->cache, list)
                         if (pos-- == 0)
                                 return mfc;
         }
-        read_unlock(&mrt_lock);
+        rcu_read_unlock();
 
         spin_lock_bh(&mfc_unres_lock);
         it->cache = &mrt->mfc_unres_queue;
@@ -2279,7 +2286,7 @@ static void *ipmr_mfc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
         }
 
         /* exhausted cache_array, show unresolved */
-        read_unlock(&mrt_lock);
+        rcu_read_unlock();
         it->cache = &mrt->mfc_unres_queue;
         it->ct = 0;
 
@@ -2302,7 +2309,7 @@ static void ipmr_mfc_seq_stop(struct seq_file *seq, void *v)
         if (it->cache == &mrt->mfc_unres_queue)
                 spin_unlock_bh(&mfc_unres_lock);
         else if (it->cache == &mrt->mfc_cache_array[it->ct])
-                read_unlock(&mrt_lock);
+                rcu_read_unlock();
 }
 
 static int ipmr_mfc_seq_show(struct seq_file *seq, void *v)
@@ -2426,7 +2433,7 @@ int __init ip_mr_init(void)
 
         mrt_cachep = kmem_cache_create("ip_mrt_cache",
                                        sizeof(struct mfc_cache),
-                                       0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
+                                       0, SLAB_HWCACHE_ALIGN | SLAB_PANIC,
                                        NULL);
         if (!mrt_cachep)
                 return -ENOMEM;