[RFC PATCH 1/2] security, capabilities: Add CAP_SYS_MOUNT

From: Nicolas Belouin
Date: Sat Oct 21 2017 - 09:43:26 EST


With CAP_SYS_ADMIN being bloated and inapropriate for actions such
as mounting/unmounting filesystems, the creation of a new capability
is needed.
CAP_SYS_MOUNT is meant to give a process the ability to call for mount,
umount and umount2 syscalls.

Signed-off-by: Nicolas Belouin <nicolas@xxxxxxxxxx>
---
include/uapi/linux/capability.h | 5 ++++-
security/selinux/include/classmap.h | 4 ++--
2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
index 230e05d35191..ce230aa6d928 100644
--- a/include/uapi/linux/capability.h
+++ b/include/uapi/linux/capability.h
@@ -365,8 +365,11 @@ struct vfs_ns_cap_data {

#define CAP_AUDIT_READ 37

+/* Allow mounting, unmounting filesystems */

-#define CAP_LAST_CAP CAP_AUDIT_READ
+#define CAP_SYS_MOUNT 38
+
+#define CAP_LAST_CAP CAP_SYS_MOUNT

#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)

diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index 35ffb29a69cb..a873dce97fd5 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -24,9 +24,9 @@
"audit_control", "setfcap"

#define COMMON_CAP2_PERMS "mac_override", "mac_admin", "syslog", \
- "wake_alarm", "block_suspend", "audit_read"
+ "wake_alarm", "block_suspend", "audit_read", "sys_mount"

-#if CAP_LAST_CAP > CAP_AUDIT_READ
+#if CAP_LAST_CAP > CAP_SYS_MOUNT
#error New capability defined, please update COMMON_CAP2_PERMS.
#endif

--
2.14.2