sockopt: Change getsockopt() of SO_BINDTODEVICE to return an interface name
Instead of having the getsockopt() of SO_BINDTODEVICE return an index, which
will then require another call like if_indextoname() to get the actual interface
name, have it return the name directly.
This also matches the existing man page description on socket(7) which mentions
the argument being an interface name.
If the value has not been set, zero is returned and optlen will be set to zero
to indicate there is no interface name present.
Added a seqlock to protect this code path, and dev_ifname(), from someone
changing the device name via dev_change_name().
v2: Added seqlock protection while copying device name.
v3: Fixed word wrap in patch.
Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e46c830..e9929ab 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1567,6 +1567,8 @@
extern rwlock_t dev_base_lock; /* Device list lock */
+extern seqlock_t devnet_rename_seq; /* Device rename lock */
+
#define for_each_netdev(net, d) \
list_for_each_entry(d, &(net)->dev_base_head, dev_list)
diff --git a/net/core/dev.c b/net/core/dev.c
index 7304ea8..2a5f5586 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -203,6 +203,8 @@
DEFINE_RWLOCK(dev_base_lock);
EXPORT_SYMBOL(dev_base_lock);
+DEFINE_SEQLOCK(devnet_rename_seq);
+
static inline void dev_base_seq_inc(struct net *net)
{
while (++net->dev_base_seq == 0);
@@ -1091,22 +1093,31 @@
if (dev->flags & IFF_UP)
return -EBUSY;
- if (strncmp(newname, dev->name, IFNAMSIZ) == 0)
+ write_seqlock(&devnet_rename_seq);
+
+ if (strncmp(newname, dev->name, IFNAMSIZ) == 0) {
+ write_sequnlock(&devnet_rename_seq);
return 0;
+ }
memcpy(oldname, dev->name, IFNAMSIZ);
err = dev_get_valid_name(net, dev, newname);
- if (err < 0)
+ if (err < 0) {
+ write_sequnlock(&devnet_rename_seq);
return err;
+ }
rollback:
ret = device_rename(&dev->dev, dev->name);
if (ret) {
memcpy(dev->name, oldname, IFNAMSIZ);
+ write_sequnlock(&devnet_rename_seq);
return ret;
}
+ write_sequnlock(&devnet_rename_seq);
+
write_lock_bh(&dev_base_lock);
hlist_del_rcu(&dev->name_hlist);
write_unlock_bh(&dev_base_lock);
@@ -1124,6 +1135,7 @@
/* err >= 0 after dev_alloc_name() or stores the first errno */
if (err >= 0) {
err = ret;
+ write_seqlock(&devnet_rename_seq);
memcpy(dev->name, oldname, IFNAMSIZ);
goto rollback;
} else {
@@ -4148,6 +4160,7 @@
{
struct net_device *dev;
struct ifreq ifr;
+ unsigned seq;
/*
* Fetch the caller's info block.
@@ -4156,6 +4169,8 @@
if (copy_from_user(&ifr, arg, sizeof(struct ifreq)))
return -EFAULT;
+retry:
+ seq = read_seqbegin(&devnet_rename_seq);
rcu_read_lock();
dev = dev_get_by_index_rcu(net, ifr.ifr_ifindex);
if (!dev) {
@@ -4165,6 +4180,8 @@
strcpy(ifr.ifr_name, dev->name);
rcu_read_unlock();
+ if (read_seqretry(&devnet_rename_seq, seq))
+ goto retry;
if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))
return -EFAULT;
diff --git a/net/core/sock.c b/net/core/sock.c
index d4f7b58..a692ef4 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -505,7 +505,8 @@
}
EXPORT_SYMBOL(sk_dst_check);
-static int sock_bindtodevice(struct sock *sk, char __user *optval, int optlen)
+static int sock_setbindtodevice(struct sock *sk, char __user *optval,
+ int optlen)
{
int ret = -ENOPROTOOPT;
#ifdef CONFIG_NETDEVICES
@@ -562,6 +563,59 @@
return ret;
}
+static int sock_getbindtodevice(struct sock *sk, char __user *optval,
+ int __user *optlen, int len)
+{
+ int ret = -ENOPROTOOPT;
+#ifdef CONFIG_NETDEVICES
+ struct net *net = sock_net(sk);
+ struct net_device *dev;
+ char devname[IFNAMSIZ];
+ unsigned seq;
+
+ if (sk->sk_bound_dev_if == 0) {
+ len = 0;
+ goto zero;
+ }
+
+ ret = -EINVAL;
+ if (len < IFNAMSIZ)
+ goto out;
+
+retry:
+ seq = read_seqbegin(&devnet_rename_seq);
+ rcu_read_lock();
+ dev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if);
+ ret = -ENODEV;
+ if (!dev) {
+ rcu_read_unlock();
+ goto out;
+ }
+
+ strcpy(devname, dev->name);
+ rcu_read_unlock();
+ if (read_seqretry(&devnet_rename_seq, seq))
+ goto retry;
+
+ len = strlen(devname) + 1;
+
+ ret = -EFAULT;
+ if (copy_to_user(optval, devname, len))
+ goto out;
+
+zero:
+ ret = -EFAULT;
+ if (put_user(len, optlen))
+ goto out;
+
+ ret = 0;
+
+out:
+#endif
+
+ return ret;
+}
+
static inline void sock_valbool_flag(struct sock *sk, int bit, int valbool)
{
if (valbool)
@@ -589,7 +643,7 @@
*/
if (optname == SO_BINDTODEVICE)
- return sock_bindtodevice(sk, optval, optlen);
+ return sock_setbindtodevice(sk, optval, optlen);
if (optlen < sizeof(int))
return -EINVAL;
@@ -1075,15 +1129,17 @@
case SO_NOFCS:
v.val = sock_flag(sk, SOCK_NOFCS);
break;
+
case SO_BINDTODEVICE:
- v.val = sk->sk_bound_dev_if;
- break;
+ return sock_getbindtodevice(sk, optval, optlen, len);
+
case SO_GET_FILTER:
len = sk_get_filter(sk, (struct sock_filter __user *)optval, len);
if (len < 0)
return len;
goto lenout;
+
default:
return -ENOPROTOOPT;
}