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Subject[PATCH 4.20 135/183] Revert "kill dev_ifsioc()"
Date
4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@intel.com>

[ Upstream commit 37ac39bdddc528c998a9f36db36937de923fdf2a ]

This reverts commit bf4405737f9f ("kill dev_ifsioc()").

This wasn't really unused as implied by the original commit,
it still handles the copy to/from user differently, and the
commit thus caused issues such as
https://bugzilla.kernel.org/show_bug.cgi?id=199469
and
https://bugzilla.kernel.org/show_bug.cgi?id=202273

However, deviating from a strict revert, rename dev_ifsioc()
to compat_ifreq_ioctl() to be clearer as to its purpose and
add a comment.

Cc: stable@vger.kernel.org
Fixes: bf4405737f9f ("kill dev_ifsioc()")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/socket.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)

--- a/net/socket.c
+++ b/net/socket.c
@@ -2960,6 +2960,53 @@ static int compat_ifr_data_ioctl(struct
return dev_ioctl(net, cmd, &ifreq, NULL);
}

+static int compat_ifreq_ioctl(struct net *net, struct socket *sock,
+ unsigned int cmd,
+ struct compat_ifreq __user *uifr32)
+{
+ struct ifreq __user *uifr;
+ int err;
+
+ /* Handle the fact that while struct ifreq has the same *layout* on
+ * 32/64 for everything but ifreq::ifru_ifmap and ifreq::ifru_data,
+ * which are handled elsewhere, it still has different *size* due to
+ * ifreq::ifru_ifmap (which is 16 bytes on 32 bit, 24 bytes on 64-bit,
+ * resulting in struct ifreq being 32 and 40 bytes respectively).
+ * As a result, if the struct happens to be at the end of a page and
+ * the next page isn't readable/writable, we get a fault. To prevent
+ * that, copy back and forth to the full size.
+ */
+
+ uifr = compat_alloc_user_space(sizeof(*uifr));
+ if (copy_in_user(uifr, uifr32, sizeof(*uifr32)))
+ return -EFAULT;
+
+ err = sock_do_ioctl(net, sock, cmd, (unsigned long)uifr);
+
+ if (!err) {
+ switch (cmd) {
+ case SIOCGIFFLAGS:
+ case SIOCGIFMETRIC:
+ case SIOCGIFMTU:
+ case SIOCGIFMEM:
+ case SIOCGIFHWADDR:
+ case SIOCGIFINDEX:
+ case SIOCGIFADDR:
+ case SIOCGIFBRDADDR:
+ case SIOCGIFDSTADDR:
+ case SIOCGIFNETMASK:
+ case SIOCGIFPFLAGS:
+ case SIOCGIFTXQLEN:
+ case SIOCGMIIPHY:
+ case SIOCGMIIREG:
+ if (copy_in_user(uifr32, uifr, sizeof(*uifr32)))
+ err = -EFAULT;
+ break;
+ }
+ }
+ return err;
+}
+
static int compat_sioc_ifmap(struct net *net, unsigned int cmd,
struct compat_ifreq __user *uifr32)
{
@@ -3179,6 +3226,8 @@ static int compat_sock_ioctl_trans(struc
case SIOCGMIIPHY:
case SIOCGMIIREG:
case SIOCSMIIREG:
+ return compat_ifreq_ioctl(net, sock, cmd, argp);
+
case SIOCSARP:
case SIOCGARP:
case SIOCDARP:

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