[PATCH 4.19 148/321] xfs: Fix bulkstat compat ioctls on x32 userspace.

Greg Kroah-Hartman
2019-12-03T22:51:39Z

From: Nick Bowler <nbowler@draconx.ca>

[ Upstream commit 7ca860e3c1a74ad6bd8949364073ef1044cad758 ]

The bulkstat family of ioctls are problematic on x32, because there is
a mixup of native 32-bit and 64-bit conventions. The xfs_fsop_bulkreq
struct contains pointers and 32-bit integers so that matches the native
32-bit layout, and that means the ioctl implementation goes into the
regular compat path on x32.

However, the 'ubuffer' member of that struct in turn refers to either
struct xfs_inogrp or xfs_bstat (or an array of these). On x32, those
structures match the native 64-bit layout. The compat implementation
writes out the 32-bit version of these structures. This is not the
expected format for x32 userspace, causing problems.

Fortunately the functions which actually output these xfs_inogrp and
xfs_bstat structures have an easy way to select which output format
is required, so we just need a little tweak to select the right format
on x32.

Signed-off-by: Nick Bowler <nbowler@draconx.ca>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/xfs/xfs_ioctl32.c | 34 ++++++++++++++++++++++++++++++----
1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
index 4c34efcbf7e80..b044f7d36782c 100644
--- a/fs/xfs/xfs_ioctl32.c
+++ b/fs/xfs/xfs_ioctl32.c
@@ -241,6 +241,32 @@ xfs_compat_ioc_bulkstat(
int done;
int error;

+ /*
+ * Output structure handling functions. Depending on the command,
+ * either the xfs_bstat and xfs_inogrp structures are written out
+ * to userpace memory via bulkreq.ubuffer. Normally the compat
+ * functions and structure size are the correct ones to use ...
+ */
+ inumbers_fmt_pf inumbers_func = xfs_inumbers_fmt_compat;
+ bulkstat_one_pf bs_one_func = xfs_bulkstat_one_compat;
+ size_t bs_one_size = sizeof(struct compat_xfs_bstat);
+
+#ifdef CONFIG_X86_X32
+ if (in_x32_syscall()) {
+ /*
+ * ... but on x32 the input xfs_fsop_bulkreq has pointers
+ * which must be handled in the "compat" (32-bit) way, while
+ * the xfs_bstat and xfs_inogrp structures follow native 64-
+ * bit layout convention. So adjust accordingly, otherwise
+ * the data written out in compat layout will not match what
+ * x32 userspace expects.
+ */
+ inumbers_func = xfs_inumbers_fmt;
+ bs_one_func = xfs_bulkstat_one;
+ bs_one_size = sizeof(struct xfs_bstat);
+ }
+#endif
+
/* done = 1 if there are more stats to get and if bulkstat */
/* should be called again (unused here, but used in dmapi) */

@@ -272,15 +298,15 @@ xfs_compat_ioc_bulkstat(

if (cmd == XFS_IOC_FSINUMBERS_32) {
error = xfs_inumbers(mp, &inlast, &count,
- bulkreq.ubuffer, xfs_inumbers_fmt_compat);
+ bulkreq.ubuffer, inumbers_func);
} else if (cmd == XFS_IOC_FSBULKSTAT_SINGLE_32) {
int res;

- error = xfs_bulkstat_one_compat(mp, inlast, bulkreq.ubuffer,
- sizeof(compat_xfs_bstat_t), NULL, &res);
+ error = bs_one_func(mp, inlast, bulkreq.ubuffer,
+ bs_one_size, NULL, &res);
} else if (cmd == XFS_IOC_FSBULKSTAT_32) {
error = xfs_bulkstat(mp, &inlast, &count,
- xfs_bulkstat_one_compat, sizeof(compat_xfs_bstat_t),
+ bs_one_func, bs_one_size,
bulkreq.ubuffer, &done);
} else
error = -EINVAL;
--
2.20.1