Re: [PATCH net-next] sockopt: Make SO_BINDTODEVICE readable
flat view
From: Brian Haley <hidden>
Date: 2012-10-22 18:04:50
Subsystem:
networking [general], networking [sockets], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Kuniyuki Iwashima, Willem de Bruijn, Linus Torvalds
On 10/19/2012 05:55 AM, Pavel Emelyanov wrote:
quoted hunk ↗ jump to hunk
The SO_BINDTODEVICE option is the only SOL_SOCKET one that can be set, but cannot be get via sockopt API. The only way we can find the device id a socket is bound to is via sock-diag interface. But the diag works only on hashed sockets, while the opt in question can be set for yet unhashed one. That said, in order to know what device a socket is bound to (we do want to know this in checkpoint-restore project) I propose to make this option getsockopt-able and report the respective device index. Another solution to the problem might be to teach the sock-diag reporting info on unhashed sockets. Should I go this way instead? Signed-off-by: Pavel Emelyanov <redacted> ---diff --git a/net/core/sock.c b/net/core/sock.c index 8a146cf..c49412c 100644 --- a/net/core/sock.c +++ b/net/core/sock.c@@ -1074,6 +1074,9 @@ int sock_getsockopt(struct socket *sock, int level, int optname, case SO_NOFCS: v.val = sock_flag(sk, SOCK_NOFCS); break; + case SO_BINDTODEVICE: + v.val = sk->sk_bound_dev_if; + break; default: return -ENOPROTOOPT; }
Doesn't this make the set and get non-symmetrical? For example, setsockopt() would take "eth0", but getsockopt() would return 2. The following patch would return a string, or -ENODEV if not set. -Brian --- Change getsockopt(SO_BINDTODEVICE) to be symmetrical with setsockopt() by returning the interface name as a string. Signed-off-by: Brian Haley <redacted>
diff --git a/net/core/sock.c b/net/core/sock.c
index c49412c..69b9d92 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c@@ -505,7 +505,8 @@ struct dst_entry *sk_dst_check(struct sock *sk, u32 cookie) } 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 +563,49 @@ out: 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]; + + ret = 0; + if (sk->sk_bound_dev_if == 0) + goto out; + + ret = -EINVAL; + if (len < IFNAMSIZ) + goto out; + if (len > IFNAMSIZ) + len = IFNAMSIZ; + + rcu_read_lock(); + dev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if); + if (dev) + strcpy(dev->name, devname); + rcu_read_unlock(); + ret = -ENODEV; + if (!dev) + goto out; + + ret = -EFAULT; + if (copy_to_user(optval, devname, len)) + goto out; + + 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 +633,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname, */ if (optname == SO_BINDTODEVICE) - return sock_bindtodevice(sk, optval, optlen); + return sock_setbindtodevice(sk, optval, optlen); if (optlen < sizeof(int)) return -EINVAL;
@@ -1074,9 +1118,10 @@ int sock_getsockopt(struct socket *sock, int level, intoptname, 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); + default: return -ENOPROTOOPT; }