On Wed, Apr 22, 2020 at 04:54:36PM +0200, Christian Brauner wrote: > Tag 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 devices files 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> I was a *bit* worried about not taking a reference to the user namespace, but it doesn't look like the chain of loop_remove() -> del_gendisk() -> device_del() will allow any later access through sysfs, so I guess it's fine. Reviewed-by: Serge Hallyn <serge@xxxxxxxxxx> > --- > /* v2 */ > unchanged > - Christian Brauner <christian.brauner@xxxxxxxxxx>: > - Adapted commit message otherwise unchanged. > --- > drivers/block/loop.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index 8e21d4b33e01..2dc53bad4b48 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -2212,6 +2212,10 @@ 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); > > -- > 2.26.1
