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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 <[email protected]>
Signed-off-by: Al Viro <[email protected]>
This commit is contained in:
Al Viro 2017-06-26 13:19:16 -04:00
commit 36fd633ec9
4 changed files with 42 additions and 86 deletions
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16
net/ipv4/devinet.c
View file

@ -1188,22 +1188,25 @@ rarok:
goto out;
}
static int inet_gifconf(struct net_device *dev, char __user *buf, int len)
static int inet_gifconf(struct net_device *dev, char __user *buf, int len, int size)
{
struct in_device *in_dev = __in_dev_get_rtnl(dev);
struct in_ifaddr *ifa;
struct ifreq ifr;
int done = 0;
if (WARN_ON(size > sizeof(struct ifreq)))
goto out;
if (!in_dev)
goto out;
for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
if (!buf) {
done += sizeof(ifr);
done += size;
continue;
}
if (len < (int) sizeof(ifr))
if (len < size)
break;
memset(&ifr, 0, sizeof(struct ifreq));
strcpy(ifr.ifr_name, ifa->ifa_label);
@ -1212,13 +1215,12 @@ static int inet_gifconf(struct net_device *dev, char __user *buf, int len)
(*(struct sockaddr_in *)&ifr.ifr_addr).sin_addr.s_addr =
ifa->ifa_local;
if (copy_to_user(buf, &ifr, sizeof(struct ifreq))) {
if (copy_to_user(buf + done, &ifr, size)) {
done = -EFAULT;
break;
}
buf += sizeof(struct ifreq);
len -= sizeof(struct ifreq);
done += sizeof(struct ifreq);
len -= size;
done += size;
}
out:
return done;