ip6_tunnel: fix error code when tunnel exists

After commit 2b0bb01b6edb, the kernel returns -ENOBUFS when user tries to add
an existing tunnel with ioctl API:
$ ip -6 tunnel add ip6tnl1 mode ip6ip6 dev eth1
add tunnel "ip6tnl0" failed: No buffer space available

It's confusing, the right error is EEXIST.

This patch also change a bit the code returned:
 - ENOBUFS -> ENOMEM
 - ENOENT -> ENODEV

Fixes: 2b0bb01b6edb ("ip6_tunnel: Return an error when adding an existing tunnel.")
CC: Steffen Klassert <steffen.klassert@secunet.com>
Reported-by: Pierre Cheynier <me@pierre-cheynier.net>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 266a264ec21273147b32d75ac7bde55afdd1b4cf..ddd94eca19b3986e4fc0b1ff684eee401032815e 100644 (file)
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -314,7 +314,7 @@ out:
  *   Create tunnel matching given parameters.
  *
  * Return:
- *   created tunnel or NULL
+ *   created tunnel or error pointer
  **/
 
 static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
@@ -322,7 +322,7 @@ static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
        struct net_device *dev;
        struct ip6_tnl *t;
        char name[IFNAMSIZ];
-       int err;
+       int err = -ENOMEM;
 
        if (p->name[0])
                strlcpy(name, p->name, IFNAMSIZ);
@@ -348,7 +348,7 @@ static struct ip6_tnl *ip6_tnl_create(struct net *net, struct __ip6_tnl_parm *p)
 failed_free:
        ip6_dev_free(dev);
 failed:
-       return NULL;
+       return ERR_PTR(err);
 }
 
 /**
@@ -362,7 +362,7 @@ failed:
  *   tunnel device is created and registered for use.
  *
  * Return:
- *   matching tunnel or NULL
+ *   matching tunnel or error pointer
  **/
 
 static struct ip6_tnl *ip6_tnl_locate(struct net *net,
@@ -380,13 +380,13 @@ static struct ip6_tnl *ip6_tnl_locate(struct net *net,
                if (ipv6_addr_equal(local, &t->parms.laddr) &&
                    ipv6_addr_equal(remote, &t->parms.raddr)) {
                        if (create)
-                               return NULL;
+                               return ERR_PTR(-EEXIST);
 
                        return t;
                }
        }
        if (!create)
-               return NULL;
+               return ERR_PTR(-ENODEV);
        return ip6_tnl_create(net, p);
 }
 
@@ -1420,7 +1420,7 @@ ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
                        }
                        ip6_tnl_parm_from_user(&p1, &p);
                        t = ip6_tnl_locate(net, &p1, 0);
-                       if (t == NULL)
+                       if (IS_ERR(t))
                                t = netdev_priv(dev);
                } else {
                        memset(&p, 0, sizeof(p));
@@ -1445,7 +1445,7 @@ ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
                ip6_tnl_parm_from_user(&p1, &p);
                t = ip6_tnl_locate(net, &p1, cmd == SIOCADDTUNNEL);
                if (cmd == SIOCCHGTUNNEL) {
-                       if (t != NULL) {
+                       if (!IS_ERR(t)) {
                                if (t->dev != dev) {
                                        err = -EEXIST;
                                        break;
@@ -1457,14 +1457,15 @@ ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
                        else
                                err = ip6_tnl_update(t, &p1);
                }
-               if (t) {
+               if (!IS_ERR(t)) {
                        err = 0;
                        ip6_tnl_parm_to_user(&p, &t->parms);
                        if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
                                err = -EFAULT;
 
-               } else
-                       err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT);
+               } else {
+                       err = PTR_ERR(t);
+               }
                break;
        case SIOCDELTUNNEL:
                err = -EPERM;
@@ -1478,7 +1479,7 @@ ip6_tnl_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
                        err = -ENOENT;
                        ip6_tnl_parm_from_user(&p1, &p);
                        t = ip6_tnl_locate(net, &p1, 0);
-                       if (t == NULL)
+                       if (IS_ERR(t))
                                break;
                        err = -EPERM;
                        if (t->dev == ip6n->fb_tnl_dev)
@@ -1672,12 +1673,13 @@ static int ip6_tnl_newlink(struct net *src_net, struct net_device *dev,
                           struct nlattr *tb[], struct nlattr *data[])
 {
        struct net *net = dev_net(dev);
-       struct ip6_tnl *nt;
+       struct ip6_tnl *nt, *t;
 
        nt = netdev_priv(dev);
        ip6_tnl_netlink_parms(data, &nt->parms);
 
-       if (ip6_tnl_locate(net, &nt->parms, 0))
+       t = ip6_tnl_locate(net, &nt->parms, 0);
+       if (!IS_ERR(t))
                return -EEXIST;
 
        return ip6_tnl_create2(dev);
@@ -1697,8 +1699,7 @@ static int ip6_tnl_changelink(struct net_device *dev, struct nlattr *tb[],
        ip6_tnl_netlink_parms(data, &p);
 
        t = ip6_tnl_locate(net, &p, 0);
-
-       if (t) {
+       if (!IS_ERR(t)) {
                if (t->dev != dev)
                        return -EEXIST;
        } else