[IPV6]: Fix SIOCCHGTUNNEL bug in IPv6 tunnels

A logic bug in tunnel lookup could result in duplicate tunnels when
changing an existing device.

Signed-off-by: Ville Nuorvala <vnuorval@tcs.hut.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 46 insertions, 65 deletions

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 25bc5ed49104..fdf1a2fa3a3d 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -215,11 +215,10 @@ ip6ip6_tnl_unlink(struct ip6_tnl *t)
  *   Create tunnel matching given parameters.
  * 
  * Return: 
- *   0 on success
+ *   created tunnel or NULL
  **/
 
-static int
-ip6_tnl_create(struct ip6_tnl_parm *p, struct ip6_tnl **pt)
+static struct ip6_tnl *ip6_tnl_create(struct ip6_tnl_parm *p)
 {
         struct net_device *dev;
         struct ip6_tnl *t;
@@ -236,11 +235,11 @@ ip6_tnl_create(struct ip6_tnl_parm *p, struct ip6_tnl **pt)
                                 break;
                 }
                 if (i == IP6_TNL_MAX) 
-                        return -ENOBUFS;
+                        goto failed;
         }
         dev = alloc_netdev(sizeof (*t), name, ip6ip6_tnl_dev_setup);
         if (dev == NULL)
-                return -ENOMEM;
+                goto failed;
 
         t = netdev_priv(dev);
         dev->init = ip6ip6_tnl_dev_init;
@@ -248,13 +247,13 @@ ip6_tnl_create(struct ip6_tnl_parm *p, struct ip6_tnl **pt)
 
         if ((err = register_netdevice(dev)) < 0) {
                 free_netdev(dev);
-                return err;
+                goto failed;
         }
         dev_hold(dev);
-
         ip6ip6_tnl_link(t);
-        *pt = t;
-        return 0;
+        return t;
+failed:
+        return NULL;
 }
 
 /**
@@ -268,32 +267,23 @@ ip6_tnl_create(struct ip6_tnl_parm *p, struct ip6_tnl **pt)
  *   tunnel device is created and registered for use.
  *
  * Return:
- *   0 if tunnel located or created,
- *   -EINVAL if parameters incorrect,
- *   -ENODEV if no matching tunnel available
+ *   matching tunnel or NULL
  **/
 
-static int
-ip6ip6_tnl_locate(struct ip6_tnl_parm *p, struct ip6_tnl **pt, int create)
+static struct ip6_tnl *ip6ip6_tnl_locate(struct ip6_tnl_parm *p, int create)
 {
         struct in6_addr *remote = &p->raddr;
         struct in6_addr *local = &p->laddr;
         struct ip6_tnl *t;
 
-        if (p->proto != IPPROTO_IPV6)
-                return -EINVAL;
-
         for (t = *ip6ip6_bucket(p); t; t = t->next) {
                 if (ipv6_addr_equal(local, &t->parms.laddr) &&
-                    ipv6_addr_equal(remote, &t->parms.raddr)) {
-                        *pt = t;
-                        return (create ? -EEXIST : 0);
-                }
+                    ipv6_addr_equal(remote, &t->parms.raddr))
+                        return t;
         }
         if (!create)
-                return -ENODEV;
-        
-        return ip6_tnl_create(p, pt);
+                return NULL;
+        return ip6_tnl_create(p);
 }
 
 /**
@@ -920,26 +910,20 @@ static int
 ip6ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 {
         int err = 0;
-        int create;
         struct ip6_tnl_parm p;
         struct ip6_tnl *t = NULL;
 
         switch (cmd) {
         case SIOCGETTUNNEL:
                 if (dev == ip6ip6_fb_tnl_dev) {
-                        if (copy_from_user(&p,
-                                           ifr->ifr_ifru.ifru_data,
-                                           sizeof (p))) {
+                        if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof (p))) {
                                 err = -EFAULT;
                                 break;
                         }
-                        if ((err = ip6ip6_tnl_locate(&p, &t, 0)) == -ENODEV)
-                                t = netdev_priv(dev);
-                        else if (err)
-                                break;
-                } else
+                        t = ip6ip6_tnl_locate(&p, 0);
+                }
+                if (t == NULL)
                         t = netdev_priv(dev);
-
                 memcpy(&p, &t->parms, sizeof (p));
                 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof (p))) {
                         err = -EFAULT;
@@ -948,35 +932,36 @@ ip6ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
         case SIOCADDTUNNEL:
         case SIOCCHGTUNNEL:
                 err = -EPERM;
-                create = (cmd == SIOCADDTUNNEL);
                 if (!capable(CAP_NET_ADMIN))
                         break;
-                if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof (p))) {
-                        err = -EFAULT;
+                err = -EFAULT;
+                if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof (p)))
                         break;
-                }
-                if (!create && dev != ip6ip6_fb_tnl_dev) {
-                        t = netdev_priv(dev);
-                }
-                if (!t && (err = ip6ip6_tnl_locate(&p, &t, create))) {
+                err = -EINVAL;
+                if (p.proto != IPPROTO_IPV6)
                         break;
-                }
-                if (cmd == SIOCCHGTUNNEL) {
-                        if (t->dev != dev) {
-                                err = -EEXIST;
-                                break;
-                        }
+                t = ip6ip6_tnl_locate(&p, cmd == SIOCADDTUNNEL);
+                if (dev != ip6ip6_fb_tnl_dev && cmd == SIOCCHGTUNNEL) {
+                        if (t != NULL) {
+                                if (t->dev != dev) {
+                                        err = -EEXIST;
+                                        break;
+                                }
+                        } else
+                                t = netdev_priv(dev);
+
                         ip6ip6_tnl_unlink(t);
                         err = ip6ip6_tnl_change(t, &p);
                         ip6ip6_tnl_link(t);
                         netdev_state_change(dev);
                 }
-                if (copy_to_user(ifr->ifr_ifru.ifru_data,
-                                 &t->parms, sizeof (p))) {
-                        err = -EFAULT;
-                } else {
+                if (t) {
                         err = 0;
-                }
+                        if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof (p)))
+                                err = -EFAULT;
+
+                } else
+                        err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
                 break;
         case SIOCDELTUNNEL:
                 err = -EPERM;
@@ -984,22 +969,18 @@ ip6ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
                         break;
 
                 if (dev == ip6ip6_fb_tnl_dev) {
-                        if (copy_from_user(&p, ifr->ifr_ifru.ifru_data,
-                                           sizeof (p))) {
-                                err = -EFAULT;
+                        err = -EFAULT;
+                        if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof (p)))
                                 break;
-                        }
-                        err = ip6ip6_tnl_locate(&p, &t, 0);
-                        if (err)
+                        err = -ENOENT;
+                        if ((t = ip6ip6_tnl_locate(&p, 0)) == NULL)
                                 break;
-                        if (t == netdev_priv(ip6ip6_fb_tnl_dev)) {
-                                err = -EPERM;
+                        err = -EPERM;
+                        if (t->dev == ip6ip6_fb_tnl_dev)
                                 break;
-                        }
-                } else {
-                        t = netdev_priv(dev);
+                        dev = t->dev;
                 }
-                err = unregister_netdevice(t->dev);
+                err = unregister_netdevice(dev);
                 break;
         default:
                 err = -EINVAL;