[PATCH 2/3] xfs: disallow broken ioctls without compat-32-bit-time

Arnd Bergmann
2019-12-18T16:40:18Z

When building a kernel that disables support for 32-bit time_t
system calls, it also makes sense to disable the old xfs_bstat
ioctls completely, as they truncate the timestamps to 32-bit
values once the extended times are supported.

Any application using these needs to be updated to use the v5
interfaces.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
fs/xfs/xfs_ioctl.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 7b35d62ede9f..d43582e933a0 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -36,6 +36,7 @@
#include "xfs_reflink.h"
#include "xfs_ioctl.h"

+#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/namei.h>

@@ -617,6 +618,23 @@ xfs_fsinumbers_fmt(
return xfs_ibulk_advance(breq, sizeof(struct xfs_inogrp));
}

+/* disallow y2038-unsafe ioctls with CONFIG_COMPAT_32BIT_TIME=n */
+static bool xfs_have_compat_bstat_time32(unsigned int cmd)
+{
+ if (IS_ENABLED(CONFIG_COMPAT_32BIT_TIME))
+ return true;
+
+ if (IS_ENABLED(CONFIG_64BIT) && !in_compat_syscall())
+ return true;
+
+ if (cmd == XFS_IOC_FSBULKSTAT_SINGLE ||
+ cmd == XFS_IOC_FSBULKSTAT ||
+ cmd == XFS_IOC_SWAPEXT)
+ return false;
+
+ return true;
+}
+
STATIC int
xfs_ioc_fsbulkstat(
xfs_mount_t *mp,
@@ -637,6 +655,9 @@ xfs_ioc_fsbulkstat(
if (!capable(CAP_SYS_ADMIN))
return -EPERM;

+ if (!xfs_have_compat_bstat_time32(cmd))
+ return -EINVAL;
+
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;

@@ -1815,6 +1836,11 @@ xfs_ioc_swapext(
struct fd f, tmp;
int error = 0;

+ if (!xfs_have_compat_bstat_time32(XFS_IOC_SWAPEXT)) {
+ error = -EINVAL;
+ goto out;
+ }
+
/* Pull information for the target fd */
f = fdget((int)sxp->sx_fdtarget);
if (!f.file) {
--
2.20.0