Re: [kernel-hardening] [RFC PATCH 1/2] security, capabilities: create CAP_TRUSTED
From: Casey Schaufler <hidden>
Date: 2017-10-21 17:25:21
On 10/21/2017 6:45 AM, Nicolas Belouin wrote:
with CAP_SYS_ADMIN being bloated, the usefulness of using it to flag a process to be entrusted for e.g reading and writing trusted xattr is near zero. CAP_TRUSTED aims to provide userland with a way to mark a process as entrusted to do specific (not specially admin-centered) actions. It would for example allow a process to red/write the trusted xattrs.
Please explain how this is different from CAP_MAC_ADMIN in any existing use case. If it is significantly different, how would the two interact?
quoted hunk
Signed-off-by: Nicolas Belouin <redacted> --- include/uapi/linux/capability.h | 6 +++++- security/selinux/include/classmap.h | 5 +++-- 2 files changed, 8 insertions(+), 3 deletions(-)diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h index ce230aa6d928..27e457b93c84 100644 --- a/include/uapi/linux/capability.h +++ b/include/uapi/linux/capability.h@@ -369,7 +369,11 @@ struct vfs_ns_cap_data { #define CAP_SYS_MOUNT 38 -#define CAP_LAST_CAP CAP_SYS_MOUNT +/* Allow read/write trusted xattr */ + +#define CAP_TRUSTED 39 + +#define CAP_LAST_CAP CAP_TRUSTED #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 a873dce97fd5..f5dc8e109f5a 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h@@ -24,9 +24,10 @@ "audit_control", "setfcap" #define COMMON_CAP2_PERMS "mac_override", "mac_admin", "syslog", \ - "wake_alarm", "block_suspend", "audit_read", "sys_mount" + "wake_alarm", "block_suspend", "audit_read", "sys_mount", \ + "trusted" -#if CAP_LAST_CAP > CAP_SYS_MOUNT +#if CAP_LAST_CAP > CAP_TRUSTED #error New capability defined, please update COMMON_CAP2_PERMS. #endif