Unverified Commit e83f0b5d authored by Christian Brauner's avatar Christian Brauner
Browse files

nsfs: support exhaustive file handles 



Pidfd file handles are exhaustive meaning they don't require a handle on
another pidfd to pass to open_by_handle_at() so it can derive the
filesystem to decode in. Instead it can be derived from the file
handle itself. The same is possible for namespace file handles.

Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 5222470b

fs/fhandle.c

+6 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/personality.h>

#include <linux/uaccess.h>

#include <linux/compat.h>

#include <linux/nsfs.h>

#include "internal.h"

#include "mount.h"
@@ -189,6 +190,11 @@ static int get_path_anchor(int fd, struct path *root) 
		return 0;

	}



	if (fd == FD_NSFS_ROOT) {

		nsfs_get_root(root);

		return 0;

	}



	return -EBADF;

}

fs/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -355,3 +355,4 @@ int anon_inode_getattr(struct mnt_idmap *idmap, const struct path *path, 
int anon_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,

		       struct iattr *attr);

void pidfs_get_root(struct path *path);

void nsfs_get_root(struct path *path);

fs/nsfs.c

+10 −0
Original line number Diff line number Diff line
@@ -25,6 +25,14 @@ 


static struct vfsmount *nsfs_mnt;



static struct path nsfs_root_path = {};



void nsfs_get_root(struct path *path)

{

	*path = nsfs_root_path;

	path_get(path);

}



static long ns_ioctl(struct file *filp, unsigned int ioctl,

			unsigned long arg);

static const struct file_operations ns_file_operations = {
@@ -598,4 +606,6 @@ void __init nsfs_init(void) 
	if (IS_ERR(nsfs_mnt))

		panic("can't set nsfs up\n");

	nsfs_mnt->mnt_sb->s_flags &= ~SB_NOUSER;

	nsfs_root_path.mnt = nsfs_mnt;

	nsfs_root_path.dentry = nsfs_mnt->mnt_root;

}

include/uapi/linux/fcntl.h

+1 −0
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ 
#define PIDFD_SELF_THREAD_GROUP		-10001 /* Current thread group leader. */



#define FD_PIDFS_ROOT			-10002 /* Root of the pidfs filesystem */

#define FD_NSFS_ROOT			-10003 /* Root of the nsfs filesystem */

#define FD_INVALID			-10009 /* Invalid file descriptor: -10000 - EBADF = -10009 */



/* Generic flags for the *at(2) family of syscalls. */