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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

79
net/socket.c
View file

@ -961,10 +961,22 @@ static long sock_do_ioctl(struct net *net, struct socket *sock,
* If this ioctl is unknown try to hand it down
* to the NIC driver.
*/
if (err == -ENOIOCTLCMD)
err = dev_ioctl(net, cmd, argp);
if (err != -ENOIOCTLCMD)
return err;
return err;
if (cmd == SIOCGIFCONF) {
struct ifconf ifc;
if (copy_from_user(&ifc, argp, sizeof(struct ifconf)))
return -EFAULT;
rtnl_lock();
err = dev_ifconf(net, &ifc, sizeof(struct ifreq));
rtnl_unlock();
if (!err && copy_to_user(argp, &ifc, sizeof(struct ifconf)))
err = -EFAULT;
return err;
}
return dev_ioctl(net, cmd, argp);
}
/*
@ -2673,70 +2685,25 @@ static int dev_ifname32(struct net *net, struct compat_ifreq __user *uifr32)
return 0;
}
static int dev_ifconf(struct net *net, struct compat_ifconf __user *uifc32)
static int compat_dev_ifconf(struct net *net, struct compat_ifconf __user *uifc32)
{
struct compat_ifconf ifc32;
struct ifconf ifc;
struct ifconf __user *uifc;
struct compat_ifreq __user *ifr32;
struct ifreq __user *ifr;
unsigned int i, j;
int err;
if (copy_from_user(&ifc32, uifc32, sizeof(struct compat_ifconf)))
return -EFAULT;
memset(&ifc, 0, sizeof(ifc));
if (ifc32.ifcbuf == 0) {
ifc32.ifc_len = 0;
ifc.ifc_len = 0;
ifc.ifc_req = NULL;
uifc = compat_alloc_user_space(sizeof(struct ifconf));
} else {
size_t len = ((ifc32.ifc_len / sizeof(struct compat_ifreq)) + 1) *
sizeof(struct ifreq);
uifc = compat_alloc_user_space(sizeof(struct ifconf) + len);
ifc.ifc_len = len;
ifr = ifc.ifc_req = (void __user *)(uifc + 1);
ifr32 = compat_ptr(ifc32.ifcbuf);
for (i = 0; i < ifc32.ifc_len; i += sizeof(struct compat_ifreq)) {
if (copy_in_user(ifr, ifr32, sizeof(struct compat_ifreq)))
return -EFAULT;
ifr++;
ifr32++;
}
}
if (copy_to_user(uifc, &ifc, sizeof(struct ifconf)))
return -EFAULT;
ifc.ifc_len = ifc32.ifc_len;
ifc.ifc_req = compat_ptr(ifc32.ifcbuf);
err = dev_ioctl(net, SIOCGIFCONF, uifc);
rtnl_lock();
err = dev_ifconf(net, &ifc, sizeof(struct compat_ifreq));
rtnl_unlock();
if (err)
return err;
if (copy_from_user(&ifc, uifc, sizeof(struct ifconf)))
return -EFAULT;
ifr = ifc.ifc_req;
ifr32 = compat_ptr(ifc32.ifcbuf);
for (i = 0, j = 0;
i + sizeof(struct compat_ifreq) <= ifc32.ifc_len && j < ifc.ifc_len;
i += sizeof(struct compat_ifreq), j += sizeof(struct ifreq)) {
if (copy_in_user(ifr32, ifr, sizeof(struct compat_ifreq)))
return -EFAULT;
ifr32++;
ifr++;
}
if (ifc32.ifcbuf == 0) {
/* Translate from 64-bit structure multiple to
* a 32-bit one.
*/
i = ifc.ifc_len;
i = ((i / sizeof(struct ifreq)) * sizeof(struct compat_ifreq));
ifc32.ifc_len = i;
} else {
ifc32.ifc_len = i;
}
ifc32.ifc_len = ifc.ifc_len;
if (copy_to_user(uifc32, &ifc32, sizeof(struct compat_ifconf)))
return -EFAULT;
@ -3133,7 +3100,7 @@ static int compat_sock_ioctl_trans(struct file *file, struct socket *sock,
case SIOCGIFNAME:
return dev_ifname32(net, argp);
case SIOCGIFCONF:
return dev_ifconf(net, argp);
return compat_dev_ifconf(net, argp);
case SIOCETHTOOL:
return ethtool_ioctl(net, argp);
case SIOCWANDEV: