[PATCH] vfs: define new lookup flag for chdir

In the "operation does permission checking" model used by fuse, chdir
permission is not checked, since there's no chdir method.

For this case set a lookup flag, which will be passed to ->permission(), so
fuse can distinguish it from permission checks for other operations.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 4 insertions, 2 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 409ce6a7cca4..f85b2a282f13 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -776,7 +776,7 @@ static int fuse_permission(struct inode *inode, int mask, struct nameidata *nd)
                 if ((mask & MAY_EXEC) && !S_ISDIR(mode) && !(mode & S_IXUGO))
                         return -EACCES;
 
-                if (nd && (nd->flags & LOOKUP_ACCESS))
+                if (nd && (nd->flags & (LOOKUP_ACCESS | LOOKUP_CHDIR)))
                         return fuse_access(inode, mask);
                 return 0;
         }
diff --git a/fs/open.c b/fs/open.c
index 303f06d2a7b9..1574d8fe4909 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -546,7 +546,8 @@ asmlinkage long sys_chdir(const char __user * filename)
         struct nameidata nd;
         int error;
 
-        error = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &nd);
+        error = __user_walk(filename,
+                            LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd);
         if (error)
                 goto out;
 
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 45511a5918d3..c6470ba00668 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -54,6 +54,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
 #define LOOKUP_OPEN             (0x0100)
 #define LOOKUP_CREATE           (0x0200)
 #define LOOKUP_ACCESS           (0x0400)
+#define LOOKUP_CHDIR            (0x0800)
 
 extern int FASTCALL(__user_walk(const char __user *, unsigned, struct nameidata *));
 extern int FASTCALL(__user_walk_fd(int dfd, const char __user *, unsigned, struct nameidata *));