[SCTP]: Handle address add/delete events in a more efficient way.

Currently in SCTP, we maintain a local address list by rebuilding the whole
list from the device list whenever we get a address add/delete event.

This patch fixes it by only adding/deleting the address for which we
receive the event.

Also removed the sctp_local_addr_lock() which is no longer needed as we
now use list_for_each_safe() to traverse this list. This fixes the bugs
in sctp_copy_laddrs_xxx() routines where we do copy_to_user() while
holding this lock.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 79 insertions, 62 deletions

diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index 3c3e560087ca..d8d36dee5ab6 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -78,8 +78,44 @@
 
 #include <asm/uaccess.h>
 
+/* Event handler for inet6 address addition/deletion events.  */
+int sctp_inet6addr_event(struct notifier_block *this, unsigned long ev,
+                        void *ptr)
+{
+        struct inet6_ifaddr *ifa = (struct inet6_ifaddr *)ptr;
+        struct sctp_sockaddr_entry *addr;
+        struct list_head *pos, *temp;
+
+        switch (ev) {
+        case NETDEV_UP:
+                addr = kmalloc(sizeof(struct sctp_sockaddr_entry), GFP_ATOMIC);
+                if (addr) {
+                        addr->a.v6.sin6_family = AF_INET6;
+                        addr->a.v6.sin6_port = 0;
+                        memcpy(&addr->a.v6.sin6_addr, &ifa->addr,
+                                 sizeof(struct in6_addr));
+                        addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;
+                        list_add_tail(&addr->list, &sctp_local_addr_list);
+                }
+                break;
+        case NETDEV_DOWN:
+                list_for_each_safe(pos, temp, &sctp_local_addr_list) {
+                        addr = list_entry(pos, struct sctp_sockaddr_entry, list);
+                        if (ipv6_addr_equal(&addr->a.v6.sin6_addr, &ifa->addr)) {
+                                list_del(pos);
+                                kfree(addr);
+                                break;
+                        }
+                }
+
+                break;
+        }
+
+        return NOTIFY_DONE;
+}
+
 static struct notifier_block sctp_inet6addr_notifier = {
-        .notifier_call = sctp_inetaddr_event,
+        .notifier_call = sctp_inet6addr_event,
 };
 
 /* ICMP error handler. */
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index f2ba8615895b..b61f3341e0a2 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -163,7 +163,7 @@ static void sctp_v4_copy_addrlist(struct list_head *addrlist,
 /* Extract our IP addresses from the system and stash them in the
  * protocol structure.
  */
-static void __sctp_get_local_addr_list(void)
+static void sctp_get_local_addr_list(void)
 {
         struct net_device *dev;
         struct list_head *pos;
@@ -179,17 +179,8 @@ static void __sctp_get_local_addr_list(void)
         read_unlock(&dev_base_lock);
 }
 
-static void sctp_get_local_addr_list(void)
-{
-        unsigned long flags;
-
-        sctp_spin_lock_irqsave(&sctp_local_addr_lock, flags);
-        __sctp_get_local_addr_list();
-        sctp_spin_unlock_irqrestore(&sctp_local_addr_lock, flags);
-}
-
 /* Free the existing local addresses.  */
-static void __sctp_free_local_addr_list(void)
+static void sctp_free_local_addr_list(void)
 {
         struct sctp_sockaddr_entry *addr;
         struct list_head *pos, *temp;
@@ -201,27 +192,15 @@ static void __sctp_free_local_addr_list(void)
         }
 }
 
-/* Free the existing local addresses.  */
-static void sctp_free_local_addr_list(void)
-{
-        unsigned long flags;
-
-        sctp_spin_lock_irqsave(&sctp_local_addr_lock, flags);
-        __sctp_free_local_addr_list();
-        sctp_spin_unlock_irqrestore(&sctp_local_addr_lock, flags);
-}
-
 /* Copy the local addresses which are valid for 'scope' into 'bp'.  */
 int sctp_copy_local_addr_list(struct sctp_bind_addr *bp, sctp_scope_t scope,
                               gfp_t gfp, int copy_flags)
 {
         struct sctp_sockaddr_entry *addr;
         int error = 0;
-        struct list_head *pos;
-        unsigned long flags;
+        struct list_head *pos, *temp;
 
-        sctp_spin_lock_irqsave(&sctp_local_addr_lock, flags);
-        list_for_each(pos, &sctp_local_addr_list) {
+        list_for_each_safe(pos, temp, &sctp_local_addr_list) {
                 addr = list_entry(pos, struct sctp_sockaddr_entry, list);
                 if (sctp_in_scope(&addr->a, scope)) {
                         /* Now that the address is in scope, check to see if
@@ -242,7 +221,6 @@ int sctp_copy_local_addr_list(struct sctp_bind_addr *bp, sctp_scope_t scope,
         }
 
 end_copy:
-        sctp_spin_unlock_irqrestore(&sctp_local_addr_lock, flags);
         return error;
 }
 
@@ -622,18 +600,36 @@ static void sctp_v4_seq_dump_addr(struct seq_file *seq, union sctp_addr *addr)
         seq_printf(seq, "%d.%d.%d.%d ", NIPQUAD(addr->v4.sin_addr));
 }
 
-/* Event handler for inet address addition/deletion events.
- * Basically, whenever there is an event, we re-build our local address list.
- */
+/* Event handler for inet address addition/deletion events.  */
 int sctp_inetaddr_event(struct notifier_block *this, unsigned long ev,
                         void *ptr)
 {
-        unsigned long flags;
+        struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
+        struct sctp_sockaddr_entry *addr;
+        struct list_head *pos, *temp;
 
-        sctp_spin_lock_irqsave(&sctp_local_addr_lock, flags);
-        __sctp_free_local_addr_list();
-        __sctp_get_local_addr_list();
-        sctp_spin_unlock_irqrestore(&sctp_local_addr_lock, flags);
+        switch (ev) {
+        case NETDEV_UP:
+                addr = kmalloc(sizeof(struct sctp_sockaddr_entry), GFP_ATOMIC);
+                if (addr) {
+                        addr->a.v4.sin_family = AF_INET;
+                        addr->a.v4.sin_port = 0;
+                        addr->a.v4.sin_addr.s_addr = ifa->ifa_local;
+                        list_add_tail(&addr->list, &sctp_local_addr_list);
+                }
+                break;
+        case NETDEV_DOWN:
+                list_for_each_safe(pos, temp, &sctp_local_addr_list) {
+                        addr = list_entry(pos, struct sctp_sockaddr_entry, list);
+                        if (addr->a.v4.sin_addr.s_addr == ifa->ifa_local) {
+                                list_del(pos);
+                                kfree(addr);
+                                break;
+                        }
+                }
+
+                break;
+        }
 
         return NOTIFY_DONE;
 }
@@ -1172,13 +1168,12 @@ SCTP_STATIC __init int sctp_init(void)
 
         /* Initialize the local address list. */
         INIT_LIST_HEAD(&sctp_local_addr_list);
-        spin_lock_init(&sctp_local_addr_lock);
+
+        sctp_get_local_addr_list();
 
         /* Register notifier for inet address additions/deletions. */
         register_inetaddr_notifier(&sctp_inetaddr_notifier);
 
-        sctp_get_local_addr_list();
-
         __unsafe(THIS_MODULE);
         status = 0;
 out:
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 1e8132b8c4d9..fa29eae83e91 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -3821,10 +3821,9 @@ static int sctp_getsockopt_local_addrs_num_old(struct sock *sk, int len,
         sctp_assoc_t id;
         struct sctp_bind_addr *bp;
         struct sctp_association *asoc;
-        struct list_head *pos;
+        struct list_head *pos, *temp;
         struct sctp_sockaddr_entry *addr;
         rwlock_t *addr_lock;
-        unsigned long flags;
         int cnt = 0;
 
         if (len != sizeof(sctp_assoc_t))
@@ -3859,8 +3858,7 @@ static int sctp_getsockopt_local_addrs_num_old(struct sock *sk, int len,
                 addr = list_entry(bp->address_list.next,
                                   struct sctp_sockaddr_entry, list);
                 if (sctp_is_any(&addr->a)) {
-                        sctp_spin_lock_irqsave(&sctp_local_addr_lock, flags);
-                        list_for_each(pos, &sctp_local_addr_list) {
+                        list_for_each_safe(pos, temp, &sctp_local_addr_list) {
                                 addr = list_entry(pos,
                                                   struct sctp_sockaddr_entry,
                                                   list);
@@ -3869,8 +3867,6 @@ static int sctp_getsockopt_local_addrs_num_old(struct sock *sk, int len,
                                         continue;
                                 cnt++;
                         }
-                        sctp_spin_unlock_irqrestore(&sctp_local_addr_lock,
-                                                    flags);
                 } else {
                         cnt = 1;
                 }
@@ -3892,15 +3888,13 @@ done:
 static int sctp_copy_laddrs_to_user_old(struct sock *sk, __u16 port, int max_addrs,
                                         void __user *to)
 {
-        struct list_head *pos;
+        struct list_head *pos, *next;
         struct sctp_sockaddr_entry *addr;
-        unsigned long flags;
         union sctp_addr temp;
         int cnt = 0;
         int addrlen;
 
-        sctp_spin_lock_irqsave(&sctp_local_addr_lock, flags);
-        list_for_each(pos, &sctp_local_addr_list) {
+        list_for_each_safe(pos, next, &sctp_local_addr_list) {
                 addr = list_entry(pos, struct sctp_sockaddr_entry, list);
                 if ((PF_INET == sk->sk_family) && 
                     (AF_INET6 == addr->a.sa.sa_family))
@@ -3909,16 +3903,13 @@ static int sctp_copy_laddrs_to_user_old(struct sock *sk, __u16 port, int max_add
                 sctp_get_pf_specific(sk->sk_family)->addr_v4map(sctp_sk(sk),
                                                                 &temp);
                 addrlen = sctp_get_af_specific(temp.sa.sa_family)->sockaddr_len;
-                if (copy_to_user(to, &temp, addrlen)) {
-                        sctp_spin_unlock_irqrestore(&sctp_local_addr_lock,
-                                                    flags);
+                if (copy_to_user(to, &temp, addrlen))
                         return -EFAULT;
-                }
+
                 to += addrlen;
                 cnt ++;
                 if (cnt >= max_addrs) break;
         }
-        sctp_spin_unlock_irqrestore(&sctp_local_addr_lock, flags);
 
         return cnt;
 }
@@ -3926,15 +3917,13 @@ static int sctp_copy_laddrs_to_user_old(struct sock *sk, __u16 port, int max_add
 static int sctp_copy_laddrs_to_user(struct sock *sk, __u16 port,
                                     void __user **to, size_t space_left)
 {
-        struct list_head *pos;
+        struct list_head *pos, *next;
         struct sctp_sockaddr_entry *addr;
-        unsigned long flags;
         union sctp_addr temp;
         int cnt = 0;
         int addrlen;
 
-        sctp_spin_lock_irqsave(&sctp_local_addr_lock, flags);
-        list_for_each(pos, &sctp_local_addr_list) {
+        list_for_each_safe(pos, next, &sctp_local_addr_list) {
                 addr = list_entry(pos, struct sctp_sockaddr_entry, list);
                 if ((PF_INET == sk->sk_family) && 
                     (AF_INET6 == addr->a.sa.sa_family))
@@ -3945,16 +3934,13 @@ static int sctp_copy_laddrs_to_user(struct sock *sk, __u16 port,
                 addrlen = sctp_get_af_specific(temp.sa.sa_family)->sockaddr_len;
                 if(space_left<addrlen)
                         return -ENOMEM;
-                if (copy_to_user(*to, &temp, addrlen)) {
-                        sctp_spin_unlock_irqrestore(&sctp_local_addr_lock,
-                                                    flags);
+                if (copy_to_user(*to, &temp, addrlen))
                         return -EFAULT;
-                }
+
                 *to += addrlen;
                 cnt ++;
                 space_left -= addrlen;
         }
-        sctp_spin_unlock_irqrestore(&sctp_local_addr_lock, flags);
 
         return cnt;
 }