--- /dev/null
+From f44d04e696feaf13d192d942c4f14ad2e117065a Mon Sep 17 00:00:00 2001
+From: Ilya Dryomov <idryomov@gmail.com>
+Date: Thu, 3 Sep 2020 13:24:11 +0200
+Subject: rbd: require global CAP_SYS_ADMIN for mapping and unmapping
+
+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 | 12 ++++++++++++
+ 1 file changed, 12 insertions(+)
+
+--- a/drivers/block/rbd.c
++++ b/drivers/block/rbd.c
+@@ -4614,6 +4614,9 @@ static ssize_t rbd_config_info_show(stru
+ {
+ struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+
++ if (!capable(CAP_SYS_ADMIN))
++ return -EPERM;
++
+ return sprintf(buf, "%s\n", rbd_dev->config_info);
+ }
+
+@@ -4715,6 +4718,9 @@ 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;
+@@ -6192,6 +6198,9 @@ 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;
+
+@@ -6340,6 +6349,9 @@ static ssize_t do_rbd_remove(struct bus_
+ bool force = false;
+ int ret;
+
++ if (!capable(CAP_SYS_ADMIN))
++ return -EPERM;
++
+ dev_id = -1;
+ opt_buf[0] = '\0';
+ sscanf(buf, "%d %5s", &dev_id, opt_buf);