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net: separate SIOCGIFCONF handling from dev_ioctl()

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Only two of dev_ioctl() callers may pass SIOCGIFCONF to it.
Separating that codepath from the rest of dev_ioctl() allows both
to simplify dev_ioctl() itself (all other cases work with struct ifreq *)
*and* seriously simplify the compat side of that beast: all it takes
is passing to inet_gifconf() an extra argument - the size of individual
records (sizeof(struct ifreq) or sizeof(struct compat_ifreq)).  With
dev_ifconf() called directly from sock_do_ioctl()/compat_dev_ifconf()
that's easy to arrange.

As the result, compat side of SIOCGIFCONF doesn't need any
allocations, copy_in_user() back and forth, etc.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-06-26 13:19:16 -04:00
parent be1b6e8b54
commit 36fd633ec9
4 changed files with 42 additions and 86 deletions
Download patch file Download diff file Expand all files Collapse all files

29
net/core/dev_ioctl.c
View file

@ -66,9 +66,8 @@ EXPORT_SYMBOL(register_gifconf);
* Thus we will need a 'compatibility mode'.
*/
static int dev_ifconf(struct net *net, char __user *arg)
int dev_ifconf(struct net *net, struct ifconf *ifc, int size)
{
struct ifconf ifc;
struct net_device *dev;
char __user *pos;
int len;
@ -79,11 +78,8 @@ static int dev_ifconf(struct net *net, char __user *arg)
* Fetch the caller's info block.
*/
if (copy_from_user(&ifc, arg, sizeof(struct ifconf)))
return -EFAULT;
pos = ifc.ifc_buf;
len = ifc.ifc_len;
pos = ifc->ifc_buf;
len = ifc->ifc_len;
/*
* Loop over the interfaces, and write an info block for each.
@ -95,10 +91,10 @@ static int dev_ifconf(struct net *net, char __user *arg)
if (gifconf_list[i]) {
int done;
if (!pos)
done = gifconf_list[i](dev, NULL, 0);
done = gifconf_list[i](dev, NULL, 0, size);
else
done = gifconf_list[i](dev, pos + total,
len - total);
len - total, size);
if (done < 0)
return -EFAULT;
total += done;
@ -109,12 +105,12 @@ static int dev_ifconf(struct net *net, char __user *arg)
/*
* All done. Write the updated control block back to the caller.
*/
ifc.ifc_len = total;
ifc->ifc_len = total;
/*
* Both BSD and Solaris return 0 here, so we do too.
*/
return copy_to_user(arg, &ifc, sizeof(struct ifconf)) ? -EFAULT : 0;
return 0;
}
/*
@ -412,17 +408,6 @@ int dev_ioctl(struct net *net, unsigned int cmd, void __user *arg)
int ret;
char *colon;
/* One special case: SIOCGIFCONF takes ifconf argument
and requires shared lock, because it sleeps writing
to user space.
*/
if (cmd == SIOCGIFCONF) {
rtnl_lock();
ret = dev_ifconf(net, (char __user *) arg);
rtnl_unlock();
return ret;
}
if (cmd == SIOCGIFNAME)
return dev_ifname(net, (struct ifreq __user *)arg);