[PATCH] fix MAY_CHDIR/MAY_ACCESS/LOOKUP_ACCESS mess

* MAY_CHDIR is redundant - it's an equivalent of MAY_ACCESS
* MAY_ACCESS on fuse should affect only the last step of pathname resolution
* fchdir() and chroot() should pass MAY_ACCESS, for the same reason why
  chdir() needs that.
* now that we pass MAY_ACCESS explicitly in all cases, LOOKUP_ACCESS can be
  removed; it has no business being in nameidata.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/fuse/dir.c

@@ -962,7 +962,7 @@ static int fuse_permission(struct inode *inode, int mask)
 		   exist.  So if permissions are revoked this won't be
 		   noticed immediately, only after the attribute
 		   timeout has expired */
-	} else if (mask & (MAY_ACCESS | MAY_CHDIR)) {
+	} else if (mask & MAY_ACCESS) {
 		err = fuse_access(inode, mask);
 	} else if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) {
 		if (!(inode->i_mode & S_IXUGO)) {

fs/namei.c

@@ -265,8 +265,6 @@ int permission(struct inode *inode, int mask, struct nameidata *nd)
 	if (inode->i_op && inode->i_op->permission) {
 		int extra = 0;
 		if (nd) {
-			if (nd->flags & LOOKUP_ACCESS)
-				extra |= MAY_ACCESS;
 			if (nd->flags & LOOKUP_OPEN)
 				extra |= MAY_OPEN;
 		}

fs/open.c

@@ -457,11 +457,11 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
 			old_cap = cap_set_effective(current->cap_permitted);
 	}
 
-	res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
+	res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd);
 	if (res)
 		goto out;
 
-	res = vfs_permission(&nd, mode);
+	res = vfs_permission(&nd, mode | MAY_ACCESS);
 	/* SuS v2 requires we report a read only fs too */
 	if(res || !(mode & S_IWOTH) ||
 	   special_file(nd.path.dentry->d_inode->i_mode))
@@ -505,7 +505,7 @@ asmlinkage long sys_chdir(const char __user * filename)
 	if (error)
 		goto out;
 
-	error = vfs_permission(&nd, MAY_EXEC | MAY_CHDIR);
+	error = vfs_permission(&nd, MAY_EXEC | MAY_ACCESS);
 	if (error)
 		goto dput_and_out;
 
@@ -534,7 +534,7 @@ asmlinkage long sys_fchdir(unsigned int fd)
 	if (!S_ISDIR(inode->i_mode))
 		goto out_putf;
 
-	error = file_permission(file, MAY_EXEC);
+	error = file_permission(file, MAY_EXEC | MAY_ACCESS);
 	if (!error)
 		set_fs_pwd(current->fs, &file->f_path);
 out_putf:
@@ -552,7 +552,7 @@ asmlinkage long sys_chroot(const char __user * filename)
 	if (error)
 		goto out;
 
-	error = vfs_permission(&nd, MAY_EXEC);
+	error = vfs_permission(&nd, MAY_EXEC | MAY_ACCESS);
 	if (error)
 		goto dput_and_out;
 

include/linux/fs.h

@@ -61,8 +61,7 @@ extern int dir_notify_enable;
 #define MAY_READ 4
 #define MAY_APPEND 8
 #define MAY_ACCESS 16
-#define MAY_CHDIR 32
-#define MAY_OPEN 64
+#define MAY_OPEN 32
 
 #define FMODE_READ 1
 #define FMODE_WRITE 2

include/linux/namei.h

@@ -53,7 +53,6 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
  */
 #define LOOKUP_OPEN		(0x0100)
 #define LOOKUP_CREATE		(0x0200)
-#define LOOKUP_ACCESS		(0x0400)
 
 extern int __user_walk(const char __user *, unsigned, struct nameidata *);
 extern int __user_walk_fd(int dfd, const char __user *, unsigned, struct nameidata *);