Commit 6f45b656 authored by David Howells's avatar David Howells Committed by Al Viro
Browse files

Add an AT_NO_AUTOMOUNT flag to suppress terminal automount 



Add an AT_NO_AUTOMOUNT flag to suppress terminal automounting of automount
point directories.  This can be used by fstatat() users to permit the
gathering of attributes on an automount point and also prevent
mass-automounting of a directory of automount points by ls.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarIan Kent <raven@themaw.net>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent cc53ce53

fs/namei.c

+6 −0
Original line number Diff line number Diff line
@@ -908,6 +908,12 @@ static int follow_automount(struct path *path, unsigned flags, 
	if (!path->dentry->d_op || !path->dentry->d_op->d_automount)

		return -EREMOTE;



	/* We don't want to mount if someone supplied AT_NO_AUTOMOUNT

	 * and this is the terminal part of the path.

	 */

	if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE))

		return -EISDIR; /* we actually want to stop here */



	/* We want to mount if someone is trying to open/create a file of any

	 * type under the mountpoint, wants to traverse through the mountpoint

	 * or wants to open the mounted directory.

fs/stat.c

+3 −1
Original line number Diff line number Diff line
@@ -75,11 +75,13 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat, 
	int error = -EINVAL;

	int lookup_flags = 0;



	if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)

	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT)) != 0)

		goto out;



	if (!(flag & AT_SYMLINK_NOFOLLOW))

		lookup_flags |= LOOKUP_FOLLOW;

	if (flag & AT_NO_AUTOMOUNT)

		lookup_flags |= LOOKUP_NO_AUTOMOUNT;



	error = user_path_at(dfd, filename, lookup_flags, &path);

	if (error)

include/linux/fcntl.h

+1 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ 
#define AT_REMOVEDIR		0x200   /* Remove directory instead of

                                           unlinking file.  */

#define AT_SYMLINK_FOLLOW	0x400   /* Follow symbolic links.  */

#define AT_NO_AUTOMOUNT		0x800	/* Suppress terminal automount traversal */



#ifdef __KERNEL__

include/linux/namei.h

+2 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; 
 *  - ending slashes ok even for nonexistent files

 *  - internal "there are more path components" flag

 *  - dentry cache is untrusted; force a real lookup

 *  - suppress terminal automount

 */

#define LOOKUP_FOLLOW		0x0001

#define LOOKUP_DIRECTORY	0x0002
@@ -53,6 +54,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; 
#define LOOKUP_PARENT		0x0010

#define LOOKUP_REVAL		0x0020

#define LOOKUP_RCU		0x0040

#define LOOKUP_NO_AUTOMOUNT	0x0080

/*

 * Intent data

 */

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