[PATCH 4.9 72/94] xfs: verify inline directory data forks

Greg Kroah-Hartman
2017-06-05T17:00:17Z

From: Darrick J. Wong <darrick.wong@oracle.com>

commit 630a04e79dd41ff746b545d4fc052e0abb836120 upstream.

When we're reading or writing the data fork of an inline directory,
check the contents to make sure we're not overflowing buffers or eating
garbage data. xfs/348 corrupts an inline symlink into an inline
directory, triggering a buffer overflow bug.

v2: add more checks consistent with _dir2_sf_check and make the verifier
usable from anywhere.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/libxfs/xfs_dir2_priv.h | 2
fs/xfs/libxfs/xfs_dir2_sf.c | 87 +++++++++++++++++++++++++++++++++++++++++
fs/xfs/libxfs/xfs_inode_fork.c | 26 ++++++++++--
fs/xfs/libxfs/xfs_inode_fork.h | 2
fs/xfs/xfs_dir2_readdir.c | 11 -----
fs/xfs/xfs_inode.c | 12 ++++-
6 files changed, 122 insertions(+), 18 deletions(-)

--- a/fs/xfs/libxfs/xfs_dir2_priv.h
+++ b/fs/xfs/libxfs/xfs_dir2_priv.h
@@ -126,6 +126,8 @@ extern int xfs_dir2_sf_create(struct xfs
extern int xfs_dir2_sf_lookup(struct xfs_da_args *args);
extern int xfs_dir2_sf_removename(struct xfs_da_args *args);
extern int xfs_dir2_sf_replace(struct xfs_da_args *args);
+extern int xfs_dir2_sf_verify(struct xfs_mount *mp, struct xfs_dir2_sf_hdr *sfp,
+ int size);

/* xfs_dir2_readdir.c */
extern int xfs_readdir(struct xfs_inode *dp, struct dir_context *ctx,
--- a/fs/xfs/libxfs/xfs_dir2_sf.c
+++ b/fs/xfs/libxfs/xfs_dir2_sf.c
@@ -629,6 +629,93 @@ xfs_dir2_sf_check(
}
#endif /* DEBUG */

+/* Verify the consistency of an inline directory. */
+int
+xfs_dir2_sf_verify(
+ struct xfs_mount *mp,
+ struct xfs_dir2_sf_hdr *sfp,
+ int size)
+{
+ struct xfs_dir2_sf_entry *sfep;
+ struct xfs_dir2_sf_entry *next_sfep;
+ char *endp;
+ const struct xfs_dir_ops *dops;
+ xfs_ino_t ino;
+ int i;
+ int i8count;
+ int offset;
+ __uint8_t filetype;
+
+ dops = xfs_dir_get_ops(mp, NULL);
+
+ /*
+ * Give up if the directory is way too short.
+ */
+ XFS_WANT_CORRUPTED_RETURN(mp, size >
+ offsetof(struct xfs_dir2_sf_hdr, parent));
+ XFS_WANT_CORRUPTED_RETURN(mp, size >=
+ xfs_dir2_sf_hdr_size(sfp->i8count));
+
+ endp = (char *)sfp + size;
+
+ /* Check .. entry */
+ ino = dops->sf_get_parent_ino(sfp);
+ i8count = ino > XFS_DIR2_MAX_SHORT_INUM;
+ XFS_WANT_CORRUPTED_RETURN(mp, !xfs_dir_ino_validate(mp, ino));
+ offset = dops->data_first_offset;
+
+ /* Check all reported entries */
+ sfep = xfs_dir2_sf_firstentry(sfp);
+ for (i = 0; i < sfp->count; i++) {
+ /*
+ * struct xfs_dir2_sf_entry has a variable length.
+ * Check the fixed-offset parts of the structure are
+ * within the data buffer.
+ */
+ XFS_WANT_CORRUPTED_RETURN(mp,
+ ((char *)sfep + sizeof(*sfep)) < endp);
+
+ /* Don't allow names with known bad length. */
+ XFS_WANT_CORRUPTED_RETURN(mp, sfep->namelen > 0);
+ XFS_WANT_CORRUPTED_RETURN(mp, sfep->namelen < MAXNAMELEN);
+
+ /*
+ * Check that the variable-length part of the structure is
+ * within the data buffer. The next entry starts after the
+ * name component, so nextentry is an acceptable test.
+ */
+ next_sfep = dops->sf_nextentry(sfp, sfep);
+ XFS_WANT_CORRUPTED_RETURN(mp, endp >= (char *)next_sfep);
+
+ /* Check that the offsets always increase. */
+ XFS_WANT_CORRUPTED_RETURN(mp,
+ xfs_dir2_sf_get_offset(sfep) >= offset);
+
+ /* Check the inode number. */
+ ino = dops->sf_get_ino(sfp, sfep);
+ i8count += ino > XFS_DIR2_MAX_SHORT_INUM;
+ XFS_WANT_CORRUPTED_RETURN(mp, !xfs_dir_ino_validate(mp, ino));
+
+ /* Check the file type. */
+ filetype = dops->sf_get_ftype(sfep);
+ XFS_WANT_CORRUPTED_RETURN(mp, filetype < XFS_DIR3_FT_MAX);
+
+ offset = xfs_dir2_sf_get_offset(sfep) +
+ dops->data_entsize(sfep->namelen);
+
+ sfep = next_sfep;
+ }
+ XFS_WANT_CORRUPTED_RETURN(mp, i8count == sfp->i8count);
+ XFS_WANT_CORRUPTED_RETURN(mp, (void *)sfep == (void *)endp);
+
+ /* Make sure this whole thing ought to be in local format. */
+ XFS_WANT_CORRUPTED_RETURN(mp, offset +
+ (sfp->count + 2) * (uint)sizeof(xfs_dir2_leaf_entry_t) +
+ (uint)sizeof(xfs_dir2_block_tail_t) <= mp->m_dir_geo->blksize);
+
+ return 0;
+}
+
/*
* Create a new (shortform) directory.
*/
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -33,6 +33,8 @@
#include "xfs_trace.h"
#include "xfs_attr_sf.h"
#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_dir2_priv.h"

kmem_zone_t *xfs_ifork_zone;

@@ -320,6 +322,7 @@ xfs_iformat_local(
int whichfork,
int size)
{
+ int error;

/*
* If the size is unreasonable, then something
@@ -336,6 +339,14 @@ xfs_iformat_local(
return -EFSCORRUPTED;
}

+ if (S_ISDIR(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK) {
+ error = xfs_dir2_sf_verify(ip->i_mount,
+ (struct xfs_dir2_sf_hdr *)XFS_DFORK_DPTR(dip),
+ size);
+ if (error)
+ return error;
+ }
+
xfs_init_local_fork(ip, whichfork, XFS_DFORK_PTR(dip, whichfork), size);
return 0;
}
@@ -856,7 +867,7 @@ xfs_iextents_copy(
* In these cases, the format always takes precedence, because the
* format indicates the current state of the fork.
*/
-void
+int
xfs_iflush_fork(
xfs_inode_t *ip,
xfs_dinode_t *dip,
@@ -866,6 +877,7 @@ xfs_iflush_fork(
char *cp;
xfs_ifork_t *ifp;
xfs_mount_t *mp;
+ int error;
static const short brootflag[2] =
{ XFS_ILOG_DBROOT, XFS_ILOG_ABROOT };
static const short dataflag[2] =
@@ -874,7 +886,7 @@ xfs_iflush_fork(
{ XFS_ILOG_DEXT, XFS_ILOG_AEXT };

if (!iip)
- return;
+ return 0;
ifp = XFS_IFORK_PTR(ip, whichfork);
/*
* This can happen if we gave up in iformat in an error path,
@@ -882,12 +894,19 @@ xfs_iflush_fork(
*/
if (!ifp) {
ASSERT(whichfork == XFS_ATTR_FORK);
- return;
+ return 0;
}
cp = XFS_DFORK_PTR(dip, whichfork);
mp = ip->i_mount;
switch (XFS_IFORK_FORMAT(ip, whichfork)) {
case XFS_DINODE_FMT_LOCAL:
+ if (S_ISDIR(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK) {
+ error = xfs_dir2_sf_verify(mp,
+ (struct xfs_dir2_sf_hdr *)ifp->if_u1.if_data,
+ ifp->if_bytes);
+ if (error)
+ return error;
+ }
if ((iip->ili_fields & dataflag[whichfork]) &&
(ifp->if_bytes > 0)) {
ASSERT(ifp->if_u1.if_data != NULL);
@@ -940,6 +959,7 @@ xfs_iflush_fork(
ASSERT(0);
break;
}
+ return 0;
}

/*
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -140,7 +140,7 @@ typedef struct xfs_ifork {
struct xfs_ifork *xfs_iext_state_to_fork(struct xfs_inode *ip, int state);

int xfs_iformat_fork(struct xfs_inode *, struct xfs_dinode *);
-void xfs_iflush_fork(struct xfs_inode *, struct xfs_dinode *,
+int xfs_iflush_fork(struct xfs_inode *, struct xfs_dinode *,
struct xfs_inode_log_item *, int);
void xfs_idestroy_fork(struct xfs_inode *, int);
void xfs_idata_realloc(struct xfs_inode *, int, int);
--- a/fs/xfs/xfs_dir2_readdir.c
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -71,22 +71,11 @@ xfs_dir2_sf_getdents(
struct xfs_da_geometry *geo = args->geo;

ASSERT(dp->i_df.if_flags & XFS_IFINLINE);
- /*
- * Give up if the directory is way too short.
- */
- if (dp->i_d.di_size < offsetof(xfs_dir2_sf_hdr_t, parent)) {
- ASSERT(XFS_FORCED_SHUTDOWN(dp->i_mount));
- return -EIO;
- }
-
ASSERT(dp->i_df.if_bytes == dp->i_d.di_size);
ASSERT(dp->i_df.if_u1.if_data != NULL);

sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;

- if (dp->i_d.di_size < xfs_dir2_sf_hdr_size(sfp->i8count))
- return -EFSCORRUPTED;
-
/*
* If the block number in the offset is out of range, we're done.
*/
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -3491,6 +3491,7 @@ xfs_iflush_int(
struct xfs_inode_log_item *iip = ip->i_itemp;
struct xfs_dinode *dip;
struct xfs_mount *mp = ip->i_mount;
+ int error;

ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
ASSERT(xfs_isiflocked(ip));
@@ -3573,9 +3574,14 @@ xfs_iflush_int(
if (ip->i_d.di_flushiter == DI_MAX_FLUSH)
ip->i_d.di_flushiter = 0;

- xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK);
- if (XFS_IFORK_Q(ip))
- xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK);
+ error = xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK);
+ if (error)
+ return error;
+ if (XFS_IFORK_Q(ip)) {
+ error = xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK);
+ if (error)
+ return error;
+ }
xfs_inobp_check(mp, bp);

/*