net: Allow userns root to control the network bridge code.

Allow an unpriviled user who has created a user namespace, and then
created a network namespace to effectively use the new network
namespace, by reducing capable(CAP_NET_ADMIN) and
capable(CAP_NET_RAW) calls to be ns_capable(net->user_ns,
CAP_NET_ADMIN), or capable(net->user_ns, CAP_NET_RAW) calls.

Allow setting bridge paramters via sysfs.

Allow all of the bridge ioctls:
BRCTL_ADD_IF
BRCTL_DEL_IF
BRCTL_SET_BRDIGE_FORWARD_DELAY
BRCTL_SET_BRIDGE_HELLO_TIME
BRCTL_SET_BRIDGE_MAX_AGE
BRCTL_SET_BRIDGE_AGING_TIME
BRCTL_SET_BRIDGE_STP_STATE
BRCTL_SET_BRIDGE_PRIORITY
BRCTL_SET_PORT_PRIORITY
BRCTL_SET_PATH_COST
BRCTL_ADD_BRIDGE
BRCTL_DEL_BRDIGE

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_ioctl.c

@@ -85,13 +85,14 @@ static int get_fdb_entries(struct net_bridge *br, void __user *userbuf,
 /* called with RTNL */
 static int add_del_if(struct net_bridge *br, int ifindex, int isadd)
 {
+	struct net *net = dev_net(br->dev);
 	struct net_device *dev;
 	int ret;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
-	dev = __dev_get_by_index(dev_net(br->dev), ifindex);
+	dev = __dev_get_by_index(net, ifindex);
 	if (dev == NULL)
 		return -EINVAL;
 
@@ -178,25 +179,25 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 	}
 
 	case BRCTL_SET_BRIDGE_FORWARD_DELAY:
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		return br_set_forward_delay(br, args[1]);
 
 	case BRCTL_SET_BRIDGE_HELLO_TIME:
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		return br_set_hello_time(br, args[1]);
 
 	case BRCTL_SET_BRIDGE_MAX_AGE:
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		return br_set_max_age(br, args[1]);
 
 	case BRCTL_SET_AGEING_TIME:
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		br->ageing_time = clock_t_to_jiffies(args[1]);
@@ -236,14 +237,14 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 	}
 
 	case BRCTL_SET_BRIDGE_STP_STATE:
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		br_stp_set_enabled(br, args[1]);
 		return 0;
 
 	case BRCTL_SET_BRIDGE_PRIORITY:
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		spin_lock_bh(&br->lock);
@@ -256,7 +257,7 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 		struct net_bridge_port *p;
 		int ret;
 
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		spin_lock_bh(&br->lock);
@@ -273,7 +274,7 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 		struct net_bridge_port *p;
 		int ret;
 
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		spin_lock_bh(&br->lock);
@@ -330,7 +331,7 @@ static int old_deviceless(struct net *net, void __user *uarg)
 	{
 		char buf[IFNAMSIZ];
 
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		if (copy_from_user(buf, (void __user *)args[1], IFNAMSIZ))
@@ -360,7 +361,7 @@ int br_ioctl_deviceless_stub(struct net *net, unsigned int cmd, void __user *uar
 	{
 		char buf[IFNAMSIZ];
 
-		if (!capable(CAP_NET_ADMIN))
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		if (copy_from_user(buf, uarg, IFNAMSIZ))

net/bridge/br_sysfs_br.c

@@ -37,7 +37,7 @@ static ssize_t store_bridge_parm(struct device *d,
 	unsigned long val;
 	int err;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!ns_capable(dev_net(br->dev)->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
 	val = simple_strtoul(buf, &endp, 0);
@@ -133,7 +133,7 @@ static ssize_t store_stp_state(struct device *d,
 	char *endp;
 	unsigned long val;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!ns_capable(dev_net(br->dev)->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
 	val = simple_strtoul(buf, &endp, 0);
@@ -166,7 +166,7 @@ static ssize_t store_group_fwd_mask(struct device *d,
 	char *endp;
 	unsigned long val;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!ns_capable(dev_net(br->dev)->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
 	val = simple_strtoul(buf, &endp, 0);
@@ -301,7 +301,7 @@ static ssize_t store_group_addr(struct device *d,
 	u8 new_addr[6];
 	int i;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!ns_capable(dev_net(br->dev)->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (sscanf(buf, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
@@ -333,7 +333,7 @@ static ssize_t store_flush(struct device *d,
 {
 	struct net_bridge *br = to_bridge(d);
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!ns_capable(dev_net(br->dev)->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
 	br_fdb_flush(br);

net/bridge/br_sysfs_if.c

@@ -221,7 +221,7 @@ static ssize_t brport_store(struct kobject * kobj,
 	char *endp;
 	unsigned long val;
 
-	if (!capable(CAP_NET_ADMIN))
+	if (!ns_capable(dev_net(p->dev)->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
 	val = simple_strtoul(buf, &endp, 0);