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authorDarrick J. Wong <djwong@kernel.org>2021-07-12 12:58:51 -0700
committerDarrick J. Wong <djwong@kernel.org>2021-07-15 09:58:42 -0700
commit5aa5b278237f356f86205c4b03d4cc64a293850a (patch)
tree6d86418555329aece03357a9b55144712f626a8d /fs
parent83193e5ebb0164d612aa620ceab7d3746e80e2a4 (diff)
xfs: don't expose misaligned extszinherit hints to userspace
Commit 603f000b15f2 changed xfs_ioctl_setattr_check_extsize to reject an attempt to set an EXTSZINHERIT extent size hint on a directory with RTINHERIT set if the hint isn't a multiple of the realtime extent size. However, I have recently discovered that it is possible to change the realtime extent size when adding a rt device to a filesystem, which means that the existence of directories with misaligned inherited hints is not an accident. As a result, it's possible that someone could have set a valid hint and added an rt volume with a different rt extent size, which invalidates the ondisk hints. After such a sequence, FSGETXATTR will report a misaligned hint, which FSSETXATTR will trip over, causing confusion if the user was doing the usual GET/SET sequence to change some other attribute. Change xfs_fill_fsxattr to omit the hint if it isn't aligned properly. Fixes: 603f000b15f2 ("xfs: validate extsz hints against rt extent size when rtinherit is set") Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs')
-rw-r--r--fs/xfs/xfs_ioctl.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 275d1c3123bd..16039ea10ac9 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1065,7 +1065,24 @@ xfs_fill_fsxattr(
fileattr_fill_xflags(fa, xfs_ip2xflags(ip));
- fa->fsx_extsize = XFS_FSB_TO_B(mp, ip->i_extsize);
+ if (ip->i_diflags & XFS_DIFLAG_EXTSIZE) {
+ fa->fsx_extsize = XFS_FSB_TO_B(mp, ip->i_extsize);
+ } else if (ip->i_diflags & XFS_DIFLAG_EXTSZINHERIT) {
+ /*
+ * Don't let a misaligned extent size hint on a directory
+ * escape to userspace if it won't pass the setattr checks
+ * later.
+ */
+ if ((ip->i_diflags & XFS_DIFLAG_RTINHERIT) &&
+ ip->i_extsize % mp->m_sb.sb_rextsize > 0) {
+ fa->fsx_xflags &= ~(FS_XFLAG_EXTSIZE |
+ FS_XFLAG_EXTSZINHERIT);
+ fa->fsx_extsize = 0;
+ } else {
+ fa->fsx_extsize = XFS_FSB_TO_B(mp, ip->i_extsize);
+ }
+ }
+
if (ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE)
fa->fsx_cowextsize = XFS_FSB_TO_B(mp, ip->i_cowextsize);
fa->fsx_projid = ip->i_projid;