compat_ioctl: handle PPPIOCGIDLE for 64-bit time_t

The ppp_idle structure is defined in terms of __kernel_time_t, which is
defined as 'long' on all architectures, and this usage is not affected
by the y2038 problem since it transports a time interval rather than an
absolute time.

However, the ppp user space defines the same structure as time_t, which
may be 64-bit wide on new libc versions even on 32-bit architectures.

It's easy enough to just handle both possible structure layouts on
all architectures, to deal with the possibility that a user space ppp
implementation comes with its own ppp_idle structure definition, as well
as to document the fact that the driver is y2038-safe.

Doing this also avoids the need for a special compat mode translation,
since 32-bit and 64-bit kernels now support the same interfaces.  The old
32-bit structure is also available on native 64-bit architectures now,
but this is harmless.

Cc: netdev@vger.kernel.org
Cc: linux-ppp@vger.kernel.org
Cc: Paul Mackerras <paulus@samba.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 5 insertions, 33 deletions

diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index 0b5a732d7afd..5e59101ef981 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -52,6 +52,7 @@
 
 #include <linux/sort.h>
 
+#ifdef CONFIG_BLOCK
 static int do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	int err;
@@ -63,7 +64,6 @@ static int do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	return vfs_ioctl(file, cmd, arg);
 }
 
-#ifdef CONFIG_BLOCK
 struct compat_sg_req_info { /* used by SG_GET_REQUEST_TABLE ioctl() */
 	char req_state;
 	char orphan;
@@ -99,33 +99,6 @@ static int sg_grt_trans(struct file *file,
 }
 #endif /* CONFIG_BLOCK */
 
-struct ppp_idle32 {
-	compat_time_t xmit_idle;
-	compat_time_t recv_idle;
-};
-#define PPPIOCGIDLE32		_IOR('t', 63, struct ppp_idle32)
-
-static int ppp_gidle(struct file *file, unsigned int cmd,
-		struct ppp_idle32 __user *idle32)
-{
-	struct ppp_idle __user *idle;
-	__kernel_time_t xmit, recv;
-	int err;
-
-	idle = compat_alloc_user_space(sizeof(*idle));
-
-	err = do_ioctl(file, PPPIOCGIDLE, (unsigned long) idle);
-
-	if (!err) {
-		if (get_user(xmit, &idle->xmit_idle) ||
-		    get_user(recv, &idle->recv_idle) ||
-		    put_user(xmit, &idle32->xmit_idle) ||
-		    put_user(recv, &idle32->recv_idle))
-			err = -EFAULT;
-	}
-	return err;
-}
-
 /*
  * simple reversible transform to make our table more evenly
  * distributed after sorting.
@@ -192,7 +165,8 @@ COMPATIBLE_IOCTL(PPPIOCGDEBUG)
 COMPATIBLE_IOCTL(PPPIOCSDEBUG)
 /* PPPIOCSPASS is translated */
 /* PPPIOCSACTIVE is translated */
-/* PPPIOCGIDLE is translated */
+COMPATIBLE_IOCTL(PPPIOCGIDLE32)
+COMPATIBLE_IOCTL(PPPIOCGIDLE64)
 COMPATIBLE_IOCTL(PPPIOCNEWUNIT)
 COMPATIBLE_IOCTL(PPPIOCATTACH)
 COMPATIBLE_IOCTL(PPPIOCDETACH)
@@ -214,16 +188,14 @@ COMPATIBLE_IOCTL(PPPIOCGL2TPSTATS)
 static long do_ioctl_trans(unsigned int cmd,
 		 unsigned long arg, struct file *file)
 {
+#ifdef CONFIG_BLOCK
 	void __user *argp = compat_ptr(arg);
 
 	switch (cmd) {
-	case PPPIOCGIDLE32:
-		return ppp_gidle(file, cmd, argp);
-#ifdef CONFIG_BLOCK
 	case SG_GET_REQUEST_TABLE:
 		return sg_grt_trans(file, cmd, argp);
-#endif
 	}
+#endif
 
 	return -ENOIOCTLCMD;
 }