Now that kernfs and the block_class optionally support setting user namespace tags we can start tagging loop devices with the namespace the loopfs instance was mounted in. This has the consequence that loopfs devices carry the correct sysfs permissions for all their core files. All other classes will continue to be correctly owned by the initial namespaces. Here is sample output: root@b1:~# mount -t loop loop /mnt root@b1:~# ln -sf /mnt/loop-control /dev/loop-control root@b1:~# losetup -f /dev/loop8 root@b1:~# ln -sf /mnt/loop8 /dev/loop8 root@b1:~# ls -al /sys/class/block/loop8 lrwxrwxrwx 1 root root 0 Apr 7 13:06 /sys/class/block/loop8 -> ../../devices/virtual/block/loop8 root@b1:~# ls -al /sys/class/block/loop8/ total 0 drwxr-xr-x 9 root root 0 Apr 7 13:06 . drwxr-xr-x 18 nobody nogroup 0 Apr 7 13:07 .. -r--r--r-- 1 root root 4096 Apr 7 13:06 alignment_offset lrwxrwxrwx 1 nobody nogroup 0 Apr 7 13:07 bdi -> ../../bdi/7:8 -r--r--r-- 1 root root 4096 Apr 7 13:06 capability -r--r--r-- 1 root root 4096 Apr 7 13:06 dev -r--r--r-- 1 root root 4096 Apr 7 13:06 discard_alignment -r--r--r-- 1 root root 4096 Apr 7 13:06 events -r--r--r-- 1 root root 4096 Apr 7 13:06 events_async -rw-r--r-- 1 root root 4096 Apr 7 13:06 events_poll_msecs -r--r--r-- 1 root root 4096 Apr 7 13:06 ext_range -r--r--r-- 1 root root 4096 Apr 7 13:06 hidden drwxr-xr-x 2 nobody nogroup 0 Apr 7 13:07 holders -r--r--r-- 1 root root 4096 Apr 7 13:06 inflight drwxr-xr-x 2 nobody nogroup 0 Apr 7 13:07 integrity drwxr-xr-x 3 nobody nogroup 0 Apr 7 13:07 mq drwxr-xr-x 2 root root 0 Apr 7 13:06 power drwxr-xr-x 3 nobody nogroup 0 Apr 7 13:07 queue -r--r--r-- 1 root root 4096 Apr 7 13:06 range -r--r--r-- 1 root root 4096 Apr 7 13:06 removable -r--r--r-- 1 root root 4096 Apr 7 13:06 ro -r--r--r-- 1 root root 4096 Apr 7 13:06 size drwxr-xr-x 2 nobody nogroup 0 Apr 7 13:07 slaves -r--r--r-- 1 root root 4096 Apr 7 13:06 stat lrwxrwxrwx 1 nobody nogroup 0 Apr 7 13:07 subsystem -> ../../../../class/block drwxr-xr-x 2 root root 0 Apr 7 13:06 trace -rw-r--r-- 1 root root 4096 Apr 7 13:06 uevent root@b1:~# Cc: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx> --- drivers/block/loop.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index b1c3436d6e38..7a14fd3e4329 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -2154,6 +2154,10 @@ static int loop_add(struct loop_device **l, int i, struct inode *inode) disk->private_data = lo; disk->queue = lo->lo_queue; sprintf(disk->disk_name, "loop%d", i); +#ifdef CONFIG_BLK_DEV_LOOPFS + if (loopfs_i_sb(inode)) + disk->user_ns = loopfs_i_sb(inode)->s_user_ns; +#endif add_disk(disk); -- 2.26.0
