fat: fat_setattr() fix

Fix fat_setattr() on the case of showexec option. If user specified
showexec option, inode->i_mode may not have S_IXUGO. This just use
inode->i_mode to fix it.

And with this patch, we don't allow chmod() on memory inode, it's just
bad behaviour. IOW, we allow changing S_IWUGO only which can be stored
to disk.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 9 deletions

diff --git a/fs/fat/file.c b/fs/fat/file.c
index b61a98f5398a..e73f13a13792 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -257,7 +257,8 @@ int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 }
 EXPORT_SYMBOL_GPL(fat_getattr);
 
-static int fat_check_mode(const struct msdos_sb_info *sbi, mode_t mode)
+static int fat_check_mode(const struct msdos_sb_info *sbi, struct inode *inode,
+                          mode_t mode)
 {
         mode_t mask, req = mode & ~S_IFMT;
 
@@ -271,7 +272,7 @@ static int fat_check_mode(const struct msdos_sb_info *sbi, mode_t mode)
          * w bits, either all (subject to umask) or none must be present.
          */
         req &= ~mask;
-        if ((req & (S_IRUGO | S_IXUGO)) != ((S_IRUGO | S_IXUGO) & ~mask))
+        if ((req & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
                 return -EPERM;
         if ((req & S_IWUGO) && ((req & S_IWUGO) != (S_IWUGO & ~mask)))
                 return -EPERM;
@@ -310,7 +311,9 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr)
         if (((attr->ia_valid & ATTR_UID) &&
              (attr->ia_uid != sbi->options.fs_uid)) ||
             ((attr->ia_valid & ATTR_GID) &&
-             (attr->ia_gid != sbi->options.fs_gid)))
+             (attr->ia_gid != sbi->options.fs_gid)) ||
+            ((attr->ia_valid & ATTR_MODE) &&
+             fat_check_mode(sbi, inode, attr->ia_mode) < 0))
                 error = -EPERM;
 
         if (error) {
@@ -319,12 +322,6 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr)
                 goto out;
         }
 
-        if (attr->ia_valid & ATTR_MODE) {
-                error = fat_check_mode(sbi, attr->ia_mode);
-                if (error != 0 && !sbi->options.quiet)
-                        goto out;
-        }
-
         error = inode_setattr(inode, attr);
         if (error)
                 goto out;