net/tun: handle compat_ioctl directly

The tun driver is the only code in the kernel that operates
on a character device with struct ifreq. Change the driver
to handle the conversion itself so we can contain the
remaining ifreq handling in the socket layer.

This also fixes a bug in the handling of invalid ioctl
numbers on an unbound tun device. The driver treats this
as a TUNSETIFF in native mode, but there is no way for
the generic compat_ioctl() function to emulate this
behaviour. Possibly the driver was only doing this
accidentally anyway, but if any code relies on this
misfeature, it now also works in compat mode.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 9c59a82784dc0b5ae16b36fa12549f670801fe05..01e99f22210e0710b8e1bfe77565b051aa849b54 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -53,6 +53,7 @@
 #include <linux/miscdevice.h>
 #include <linux/ethtool.h>
 #include <linux/rtnetlink.h>
+#include <linux/compat.h>
 #include <linux/if.h>
 #include <linux/if_arp.h>
 #include <linux/if_ether.h>
@@ -1109,8 +1110,8 @@ static int set_offload(struct net_device *dev, unsigned long arg)
        return 0;
 }
 
-static long tun_chr_ioctl(struct file *file, unsigned int cmd,
-                         unsigned long arg)
+static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
+                           unsigned long arg, int ifreq_len)
 {
        struct tun_file *tfile = file->private_data;
        struct tun_struct *tun;
@@ -1120,7 +1121,7 @@ static long tun_chr_ioctl(struct file *file, unsigned int cmd,
        int ret;
 
        if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89)
-               if (copy_from_user(&ifr, argp, sizeof ifr))
+               if (copy_from_user(&ifr, argp, ifreq_len))
                        return -EFAULT;
 
        if (cmd == TUNGETFEATURES) {
@@ -1143,7 +1144,7 @@ static long tun_chr_ioctl(struct file *file, unsigned int cmd,
                if (ret)
                        goto unlock;
 
-               if (copy_to_user(argp, &ifr, sizeof(ifr)))
+               if (copy_to_user(argp, &ifr, ifreq_len))
                        ret = -EFAULT;
                goto unlock;
        }
@@ -1161,7 +1162,7 @@ static long tun_chr_ioctl(struct file *file, unsigned int cmd,
                if (ret)
                        break;
 
-               if (copy_to_user(argp, &ifr, sizeof(ifr)))
+               if (copy_to_user(argp, &ifr, ifreq_len))
                        ret = -EFAULT;
                break;
 
@@ -1235,7 +1236,7 @@ static long tun_chr_ioctl(struct file *file, unsigned int cmd,
                /* Get hw addres */
                memcpy(ifr.ifr_hwaddr.sa_data, tun->dev->dev_addr, ETH_ALEN);
                ifr.ifr_hwaddr.sa_family = tun->dev->type;
-               if (copy_to_user(argp, &ifr, sizeof ifr))
+               if (copy_to_user(argp, &ifr, ifreq_len))
                        ret = -EFAULT;
                break;
 
@@ -1274,6 +1275,41 @@ unlock:
        return ret;
 }
 
+static long tun_chr_ioctl(struct file *file,
+                         unsigned int cmd, unsigned long arg)
+{
+       return __tun_chr_ioctl(file, cmd, arg, sizeof (struct ifreq));
+}
+
+#ifdef CONFIG_COMPAT
+static long tun_chr_compat_ioctl(struct file *file,
+                        unsigned int cmd, unsigned long arg)
+{
+       switch (cmd) {
+       case TUNSETIFF:
+       case TUNGETIFF:
+       case TUNSETTXFILTER:
+       case TUNGETSNDBUF:
+       case TUNSETSNDBUF:
+       case SIOCGIFHWADDR:
+       case SIOCSIFHWADDR:
+               arg = (unsigned long)compat_ptr(arg);
+               break;
+       default:
+               arg = (compat_ulong_t)arg;
+               break;
+       }
+
+       /*
+        * compat_ifreq is shorter than ifreq, so we must not access beyond
+        * the end of that structure. All fields that are used in this
+        * driver are compatible though, we don't need to convert the
+        * contents.
+        */
+       return __tun_chr_ioctl(file, cmd, arg, sizeof(struct compat_ifreq));
+}
+#endif /* CONFIG_COMPAT */
+
 static int tun_chr_fasync(int fd, struct file *file, int on)
 {
        struct tun_struct *tun = tun_get(file);
@@ -1356,7 +1392,10 @@ static const struct file_operations tun_fops = {
        .write = do_sync_write,
        .aio_write = tun_chr_aio_write,
        .poll   = tun_chr_poll,
-       .unlocked_ioctl = tun_chr_ioctl,
+       .unlocked_ioctl = tun_chr_ioctl,
+#ifdef CONFIG_COMPAT
+       .compat_ioctl = tun_chr_compat_ioctl,
+#endif
        .open   = tun_chr_open,
        .release = tun_chr_close,
        .fasync = tun_chr_fasync

diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index f91fd51b32e321efc97a61b0d79274ecd81533ca..c562e9a4da708dd18bcca95198d96a0bb5ed24cf 100644 (file)
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -539,12 +539,6 @@ static int dev_ifsioc(unsigned int fd, unsigned int cmd, unsigned long arg)
        set_fs (old_fs);
        if (!err) {
                switch (cmd) {
-               /* TUNSETIFF is defined as _IOW, it should be _IORW
-                * as the data is copied back to user space, but that
-                * cannot be fixed without breaking all existing apps.
-                */
-               case TUNSETIFF:
-               case TUNGETIFF:
                case SIOCGIFFLAGS:
                case SIOCGIFMETRIC:
                case SIOCGIFMTU:
@@ -1979,18 +1973,6 @@ COMPATIBLE_IOCTL(SCSI_IOCTL_SEND_COMMAND)
 COMPATIBLE_IOCTL(SCSI_IOCTL_PROBE_HOST)
 COMPATIBLE_IOCTL(SCSI_IOCTL_GET_PCI)
 #endif
-/* Big T */
-COMPATIBLE_IOCTL(TUNSETNOCSUM)
-COMPATIBLE_IOCTL(TUNSETDEBUG)
-COMPATIBLE_IOCTL(TUNSETPERSIST)
-COMPATIBLE_IOCTL(TUNSETOWNER)
-COMPATIBLE_IOCTL(TUNSETLINK)
-COMPATIBLE_IOCTL(TUNSETGROUP)
-COMPATIBLE_IOCTL(TUNGETFEATURES)
-COMPATIBLE_IOCTL(TUNSETOFFLOAD)
-COMPATIBLE_IOCTL(TUNSETTXFILTER)
-COMPATIBLE_IOCTL(TUNGETSNDBUF)
-COMPATIBLE_IOCTL(TUNSETSNDBUF)
 /* Big V */
 COMPATIBLE_IOCTL(VT_SETMODE)
 COMPATIBLE_IOCTL(VT_GETMODE)
@@ -2571,8 +2553,6 @@ HANDLE_IOCTL(SIOCSIFPFLAGS, dev_ifsioc)
 HANDLE_IOCTL(SIOCGIFPFLAGS, dev_ifsioc)
 HANDLE_IOCTL(SIOCGIFTXQLEN, dev_ifsioc)
 HANDLE_IOCTL(SIOCSIFTXQLEN, dev_ifsioc)
-HANDLE_IOCTL(TUNSETIFF, dev_ifsioc)
-HANDLE_IOCTL(TUNGETIFF, dev_ifsioc)
 HANDLE_IOCTL(SIOCETHTOOL, ethtool_ioctl)
 HANDLE_IOCTL(SIOCBONDENSLAVE, bond_ioctl)
 HANDLE_IOCTL(SIOCBONDRELEASE, bond_ioctl)