[PATCH] permission checks for chdir need special treatment only on the last step

... so we ought to pass MAY_CHDIR to vfs_permission() instead of having
it triggered on every step of preceding pathname resolution.  LOOKUP_CHDIR
is killed by that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 2 insertions, 6 deletions

diff --git a/fs/namei.c b/fs/namei.c
index ae0e56fdb742..6c76e1ee9c45 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -268,8 +268,6 @@ int permission(struct inode *inode, int mask, struct nameidata *nd)
                 if (nd) {
                         if (nd->flags & LOOKUP_ACCESS)
                                 extra |= MAY_ACCESS;
-                        if (nd->flags & LOOKUP_CHDIR)
-                                extra |= MAY_CHDIR;
                         if (nd->flags & LOOKUP_OPEN)
                                 extra |= MAY_OPEN;
                 }
diff --git a/fs/open.c b/fs/open.c
index b2e4c93aed03..8e02d42bfe44 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -501,12 +501,11 @@ asmlinkage long sys_chdir(const char __user * filename)
         struct nameidata nd;
         int error;
 
-        error = __user_walk(filename,
-                            LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd);
+        error = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &nd);
         if (error)
                 goto out;
 
-        error = vfs_permission(&nd, MAY_EXEC);
+        error = vfs_permission(&nd, MAY_EXEC | MAY_CHDIR);
         if (error)
                 goto dput_and_out;
 
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 24d88e98a626..3cf62d26d493 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -55,7 +55,6 @@ 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 __user_walk(const char __user *, unsigned, struct nameidata *);
 extern int __user_walk_fd(int dfd, const char __user *, unsigned, struct nameidata *);