[PATCH net-next v6 5/6] net: socket: simplify dev_ifconf handling

From: Arnd Bergmann
Date: Thu Jul 22 2021 - 10:29:55 EST

From: Arnd Bergmann <arnd@xxxxxxxx>

The dev_ifconf() calling conventions make compat handling
more complicated than necessary, simplify this by moving
the in_compat_syscall() check into the function.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
changes in v6:
- split register_gifconf from compat changes
---
include/linux/netdevice.h | 2 +-
net/core/dev_ioctl.c | 55 +++++++++++++++++++-----------------
net/socket.c | 59 ++++++++++-----------------------------
3 files changed, 44 insertions(+), 72 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 6630a9f0b0f0..da2c273c7e0a 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4008,7 +4008,7 @@ void netdev_rx_handler_unregister(struct net_device *dev);
bool dev_valid_name(const char *name);
int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr,
bool *need_copyout);
-int dev_ifconf(struct net *net, struct ifconf *, int);
+int dev_ifconf(struct net *net, struct ifconf __user *ifc);
int dev_ethtool(struct net *net, struct ifreq *);
unsigned int dev_get_flags(const struct net_device *);
int __dev_change_flags(struct net_device *dev, unsigned int flags,
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index c22c3dc15ce9..950e2fe5d56a 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -31,48 +31,51 @@ static int dev_ifname(struct net *net, struct ifreq *ifr)
* size eventually, and there is nothing I can do about it.
* Thus we will need a 'compatibility mode'.
*/
-
-int dev_ifconf(struct net *net, struct ifconf *ifc, int size)
+int dev_ifconf(struct net *net, struct ifconf __user *uifc)
{
struct net_device *dev;
- char __user *pos;
- int len;
- int total;
- int i;
+ void __user *pos;
+ size_t size;
+ int len, total = 0, done;

- /*
- * Fetch the caller's info block.
- */
+ /* both the ifconf and the ifreq structures are slightly different */
+ if (in_compat_syscall()) {
+ struct compat_ifconf ifc32;
+
+ if (copy_from_user(&ifc32, uifc, sizeof(struct compat_ifconf)))
+ return -EFAULT;

- pos = ifc->ifc_buf;
- len = ifc->ifc_len;
+ pos = compat_ptr(ifc32.ifcbuf);
+ len = ifc32.ifc_len;
+ size = sizeof(struct compat_ifreq);
+ } else {
+ struct ifconf ifc;

- /*
- * Loop over the interfaces, and write an info block for each.
- */
+ if (copy_from_user(&ifc, uifc, sizeof(struct ifconf)))
+ return -EFAULT;

- total = 0;
+ pos = ifc.ifc_buf;
+ len = ifc.ifc_len;
+ size = sizeof(struct ifreq);
+ }
+
+ /* Loop over the interfaces, and write an info block for each. */
+ rtnl_lock();
for_each_netdev(net, dev) {
- int done;
if (!pos)
done = inet_gifconf(dev, NULL, 0, size);
else
done = inet_gifconf(dev, pos + total,
len - total, size);
- if (done < 0)
+ if (done < 0) {
+ rtnl_unlock();
return -EFAULT;
+ }
total += done;
}
+ rtnl_unlock();

- /*
- * All done. Write the updated control block back to the caller.
- */
- ifc->ifc_len = total;
-
- /*
- * Both BSD and Solaris return 0 here, so we do too.
- */
- return 0;
+ return put_user(total, &uifc->ifc_len);
}

static int dev_getifmap(struct net_device *dev, struct ifreq *ifr)
diff --git a/net/socket.c b/net/socket.c
index 62005a12ec70..ecdb7913a3bd 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1088,6 +1088,8 @@ EXPORT_SYMBOL(vlan_ioctl_set);
static long sock_do_ioctl(struct net *net, struct socket *sock,
unsigned int cmd, unsigned long arg)
{
+ struct ifreq ifr;
+ bool need_copyout;
int err;
void __user *argp = (void __user *)arg;

@@ -1100,25 +1102,13 @@ static long sock_do_ioctl(struct net *net, struct socket *sock,
if (err != -ENOIOCTLCMD)
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;
- } else {
- struct ifreq ifr;
- bool need_copyout;
- if (copy_from_user(&ifr, argp, sizeof(struct ifreq)))
+ if (copy_from_user(&ifr, argp, sizeof(struct ifreq)))
+ return -EFAULT;
+ err = dev_ioctl(net, cmd, &ifr, &need_copyout);
+ if (!err && need_copyout)
+ if (copy_to_user(argp, &ifr, sizeof(struct ifreq)))
return -EFAULT;
- err = dev_ioctl(net, cmd, &ifr, &need_copyout);
- if (!err && need_copyout)
- if (copy_to_user(argp, &ifr, sizeof(struct ifreq)))
- return -EFAULT;
- }
+
return err;
}

@@ -1217,6 +1207,11 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg)
cmd == SIOCGSTAMP_NEW,
false);
break;
+
+ case SIOCGIFCONF:
+ err = dev_ifconf(net, argp);
+ break;
+
default:
err = sock_do_ioctl(net, sock, cmd, arg);
break;
@@ -3127,31 +3122,6 @@ void socket_seq_show(struct seq_file *seq)
#endif /* CONFIG_PROC_FS */

#ifdef CONFIG_COMPAT
-static int compat_dev_ifconf(struct net *net, struct compat_ifconf __user *uifc32)
-{
- struct compat_ifconf ifc32;
- struct ifconf ifc;
- int err;
-
- if (copy_from_user(&ifc32, uifc32, sizeof(struct compat_ifconf)))
- return -EFAULT;
-
- ifc.ifc_len = ifc32.ifc_len;
- ifc.ifc_req = compat_ptr(ifc32.ifcbuf);
-
- rtnl_lock();
- err = dev_ifconf(net, &ifc, sizeof(struct compat_ifreq));
- rtnl_unlock();
- if (err)
- return err;
-
- ifc32.ifc_len = ifc.ifc_len;
- if (copy_to_user(uifc32, &ifc32, sizeof(struct compat_ifconf)))
- return -EFAULT;
-
- return 0;
-}
-
static int compat_siocwandev(struct net *net, struct compat_ifreq __user *uifr32)
{
compat_uptr_t uptr32;
@@ -3270,8 +3240,6 @@ static int compat_sock_ioctl_trans(struct file *file, struct socket *sock,
case SIOCSIFBR:
case SIOCGIFBR:
return old_bridge_ioctl(argp);
- case SIOCGIFCONF:
- return compat_dev_ifconf(net, argp);
case SIOCWANDEV:
return compat_siocwandev(net, argp);
case SIOCGSTAMP_OLD:
@@ -3299,6 +3267,7 @@ static int compat_sock_ioctl_trans(struct file *file, struct socket *sock,
case SIOCGSKNS:
case SIOCGSTAMP_NEW:
case SIOCGSTAMPNS_NEW:
+ case SIOCGIFCONF:
return sock_ioctl(file, cmd, arg);

case SIOCGIFFLAGS:
--
2.29.2