From: Ilya Dryomov idryomov@gmail.com
commit f44d04e696feaf13d192d942c4f14ad2e117065a upstream.
It turns out that currently we rely only on sysfs attribute permissions:
$ ll /sys/bus/rbd/{add*,remove*} --w------- 1 root root 4096 Sep 3 20:37 /sys/bus/rbd/add --w------- 1 root root 4096 Sep 3 20:37 /sys/bus/rbd/add_single_major --w------- 1 root root 4096 Sep 3 20:37 /sys/bus/rbd/remove --w------- 1 root root 4096 Sep 3 20:38 /sys/bus/rbd/remove_single_major
This means that images can be mapped and unmapped (i.e. block devices can be created and deleted) by a UID 0 process even after it drops all privileges or by any process with CAP_DAC_OVERRIDE in its user namespace as long as UID 0 is mapped into that user namespace.
Be consistent with other virtual block devices (loop, nbd, dm, md, etc) and require CAP_SYS_ADMIN in the initial user namespace for mapping and unmapping, and also for dumping the configuration string and refreshing the image header.
Cc: stable@vger.kernel.org Signed-off-by: Ilya Dryomov idryomov@gmail.com Reviewed-by: Jeff Layton jlayton@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/block/rbd.c | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -3945,6 +3945,9 @@ static ssize_t rbd_image_refresh(struct struct rbd_device *rbd_dev = dev_to_rbd_dev(dev); int ret;
+ if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + ret = rbd_dev_refresh(rbd_dev); if (ret) return ret; @@ -5404,6 +5407,9 @@ static ssize_t do_rbd_add(struct bus_typ bool read_only; int rc;
+ if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + if (!try_module_get(THIS_MODULE)) return -ENODEV;
@@ -5548,6 +5554,9 @@ static ssize_t do_rbd_remove(struct bus_ bool already = false; int ret;
+ if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + ret = kstrtoul(buf, 10, &ul); if (ret) return ret;