From a07b20004793d8926f78d63eb5980559f7813404 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 5 Nov 2018 17:40:30 +0000 Subject: vfs: syscall: Add open_tree(2) to reference or clone a mount open_tree(dfd, pathname, flags) Returns an O_PATH-opened file descriptor or an error. dfd and pathname specify the location to open, in usual fashion (see e.g. fstatat(2)). flags should be an OR of some of the following: * AT_PATH_EMPTY, AT_NO_AUTOMOUNT, AT_SYMLINK_NOFOLLOW - same meanings as usual * OPEN_TREE_CLOEXEC - make the resulting descriptor close-on-exec * OPEN_TREE_CLONE or OPEN_TREE_CLONE | AT_RECURSIVE - instead of opening the location in question, create a detached mount tree matching the subtree rooted at location specified by dfd/pathname. With AT_RECURSIVE the entire subtree is cloned, without it - only the part within in the mount containing the location in question. In other words, the same as mount --rbind or mount --bind would've taken. The detached tree will be dissolved on the final close of obtained file. Creation of such detached trees requires the same capabilities as doing mount --bind. Signed-off-by: Al Viro Signed-off-by: David Howells cc: linux-api@vger.kernel.org Signed-off-by: Al Viro --- include/uapi/linux/mount.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/uapi/linux/mount.h') diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index 3f9ec42510b0..fd7ae2e7eccf 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -55,4 +55,10 @@ #define MS_MGC_VAL 0xC0ED0000 #define MS_MGC_MSK 0xffff0000 +/* + * open_tree() flags. + */ +#define OPEN_TREE_CLONE 1 /* Clone the target tree and attach the clone */ +#define OPEN_TREE_CLOEXEC O_CLOEXEC /* Close the file on execve() */ + #endif /* _UAPI_LINUX_MOUNT_H */ -- cgit v1.2.3