From: Miklos Szeredi <mszeredi@suse.cz>
permission() checks that MAY_EXEC is only allowed on regular files if
at least one execute bit is set in the file mode.
generic_permission() already ensures this, so the extra check in
permission() is superfluous.
If the filesystem defines it's own ->permission() the check may still
be needed. In this case move it after ->permission(). This is needed
because filesystems such as FUSE may need to refresh the inode
attributes before checking permissions.
This check should be moved inside ->permission(), but that's another
story.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
Index: linux/fs/namei.c
===================================================================
--- linux.orig/fs/namei.c 2007-08-09 11:01:55.000000000 +0200
+++ linux/fs/namei.c 2007-08-09 11:04:22.000000000 +0200
@@ -227,10 +227,10 @@ int generic_permission(struct inode *ino
int permission(struct inode *inode, int mask, struct nameidata *nd)
{
- umode_t mode = inode->i_mode;
int retval, submask;
if (mask & MAY_WRITE) {
+ umode_t mode = inode->i_mode;
/*
* Nobody gets write access to a read-only fs.
@@ -246,22 +246,34 @@ int permission(struct inode *inode, int
return -EACCES;
}
-
- /*
- * MAY_EXEC on regular files requires special handling: We override
- * filesystem execute permissions if the mode bits aren't set or
- * the fs is mounted with the "noexec" flag.
- */
- if ((mask & MAY_EXEC) && S_ISREG(mode) && (!(mode & S_IXUGO) ||
- (nd && nd->mnt && (nd->mnt->mnt_flags & MNT_NOEXEC))))
- return -EACCES;
+ if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) {
+ /*
+ * MAY_EXEC on regular files is denied if the fs is mounted
+ * with the "noexec" flag.
+ */
+ if (nd && nd->mnt && (nd->mnt->mnt_flags & MNT_NOEXEC))
+ return -EACCES;
+ }
/* Ordinary permission routines do not understand MAY_APPEND. */
submask = mask & ~MAY_APPEND;
- if (inode->i_op && inode->i_op->permission)
+ if (inode->i_op && inode->i_op->permission) {
retval = inode->i_op->permission(inode, submask, nd);
- else
+ if (!retval) {
+ /*
+ * Exec permission on a regular file is denied if none
+ * of the execute bits are set.
+ *
+ * This check should be done by the ->permission()
+ * method.
+ */
+ if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) &&
+ !(inode->i_mode & S_IXUGO))
+ return -EACCES;
+ }
+ } else {
retval = generic_permission(inode, submask, NULL);
+ }
if (retval)
return retval;
--
-
