[PATCH 4.9 42/51] xfs: sanity check inode mode when creating new dentry

From: Greg Kroah-Hartman
Date: Thu Feb 02 2017 - 13:40:00 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------


From: Amir Goldstein <amir73il@xxxxxxxxx>

commit fab8eef86c814c3dd46bc5d760b6e4a53d5fc5a6 upstream.

The helper xfs_dentry_to_name() is used by 2 different
classes of callers: Callers that pass zero mode and don't care
about the returned name.type field and Callers that pass
non zero mode and do care about the name.type field.

Change xfs_dentry_to_name() to not take the mode argument and
change the call sites of the first class to not pass the mode
argument.

Create a new helper xfs_dentry_mode_to_name() which does pass
the mode argument and returns -EFSCORRUPTED if mode is invalid.
Callers that translate non zero mode to on-disk file type now
check the return value and will export the error to user instead
of staging an invalid file type to be written to directory entry.

Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/xfs/xfs_iops.c | 48 +++++++++++++++++++++++++++++++++++++++---------
1 file changed, 39 insertions(+), 9 deletions(-)

--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -98,12 +98,27 @@ xfs_init_security(
static void
xfs_dentry_to_name(
struct xfs_name *namep,
+ struct dentry *dentry)
+{
+ namep->name = dentry->d_name.name;
+ namep->len = dentry->d_name.len;
+ namep->type = XFS_DIR3_FT_UNKNOWN;
+}
+
+static int
+xfs_dentry_mode_to_name(
+ struct xfs_name *namep,
struct dentry *dentry,
int mode)
{
namep->name = dentry->d_name.name;
namep->len = dentry->d_name.len;
namep->type = xfs_mode_to_ftype(mode);
+
+ if (unlikely(namep->type == XFS_DIR3_FT_UNKNOWN))
+ return -EFSCORRUPTED;
+
+ return 0;
}

STATIC void
@@ -119,7 +134,7 @@ xfs_cleanup_inode(
* xfs_init_security we must back out.
* ENOSPC can hit here, among other things.
*/
- xfs_dentry_to_name(&teardown, dentry, 0);
+ xfs_dentry_to_name(&teardown, dentry);

xfs_remove(XFS_I(dir), &teardown, XFS_I(inode));
}
@@ -154,8 +169,12 @@ xfs_generic_create(
if (error)
return error;

+ /* Verify mode is valid also for tmpfile case */
+ error = xfs_dentry_mode_to_name(&name, dentry, mode);
+ if (unlikely(error))
+ goto out_free_acl;
+
if (!tmpfile) {
- xfs_dentry_to_name(&name, dentry, mode);
error = xfs_create(XFS_I(dir), &name, mode, rdev, &ip);
} else {
error = xfs_create_tmpfile(XFS_I(dir), dentry, mode, &ip);
@@ -248,7 +267,7 @@ xfs_vn_lookup(
if (dentry->d_name.len >= MAXNAMELEN)
return ERR_PTR(-ENAMETOOLONG);

- xfs_dentry_to_name(&name, dentry, 0);
+ xfs_dentry_to_name(&name, dentry);
error = xfs_lookup(XFS_I(dir), &name, &cip, NULL);
if (unlikely(error)) {
if (unlikely(error != -ENOENT))
@@ -275,7 +294,7 @@ xfs_vn_ci_lookup(
if (dentry->d_name.len >= MAXNAMELEN)
return ERR_PTR(-ENAMETOOLONG);

- xfs_dentry_to_name(&xname, dentry, 0);
+ xfs_dentry_to_name(&xname, dentry);
error = xfs_lookup(XFS_I(dir), &xname, &ip, &ci_name);
if (unlikely(error)) {
if (unlikely(error != -ENOENT))
@@ -310,7 +329,9 @@ xfs_vn_link(
struct xfs_name name;
int error;

- xfs_dentry_to_name(&name, dentry, inode->i_mode);
+ error = xfs_dentry_mode_to_name(&name, dentry, inode->i_mode);
+ if (unlikely(error))
+ return error;

error = xfs_link(XFS_I(dir), XFS_I(inode), &name);
if (unlikely(error))
@@ -329,7 +350,7 @@ xfs_vn_unlink(
struct xfs_name name;
int error;

- xfs_dentry_to_name(&name, dentry, 0);
+ xfs_dentry_to_name(&name, dentry);

error = xfs_remove(XFS_I(dir), &name, XFS_I(d_inode(dentry)));
if (error)
@@ -359,7 +380,9 @@ xfs_vn_symlink(

mode = S_IFLNK |
(irix_symlink_mode ? 0777 & ~current_umask() : S_IRWXUGO);
- xfs_dentry_to_name(&name, dentry, mode);
+ error = xfs_dentry_mode_to_name(&name, dentry, mode);
+ if (unlikely(error))
+ goto out;

error = xfs_symlink(XFS_I(dir), &name, symname, mode, &cip);
if (unlikely(error))
@@ -395,6 +418,7 @@ xfs_vn_rename(
{
struct inode *new_inode = d_inode(ndentry);
int omode = 0;
+ int error;
struct xfs_name oname;
struct xfs_name nname;

@@ -405,8 +429,14 @@ xfs_vn_rename(
if (flags & RENAME_EXCHANGE)
omode = d_inode(ndentry)->i_mode;

- xfs_dentry_to_name(&oname, odentry, omode);
- xfs_dentry_to_name(&nname, ndentry, d_inode(odentry)->i_mode);
+ error = xfs_dentry_mode_to_name(&oname, odentry, omode);
+ if (omode && unlikely(error))
+ return error;
+
+ error = xfs_dentry_mode_to_name(&nname, ndentry,
+ d_inode(odentry)->i_mode);
+ if (unlikely(error))
+ return error;

return xfs_rename(XFS_I(odir), &oname, XFS_I(d_inode(odentry)),
XFS_I(ndir), &nname,