<[email protected]>,[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected]
From: Nicolas Belouin <[email protected]>
Message-ID: <[email protected]>
On October 21, 2017 7:25:21 PM GMT+02:00, Casey Schaufler <[email protected]> wrote:
>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?
From my point of view, CAP_MAC_ADMIN allows one to read/write security xattrs, those are meant to describe security policies. As far as I know of, trusted xattrs are intended for a privileged process to read or write arbitrary data. I don't have any real world example in mind that use trusted xattrs, but I'll try to find one.
>
>> Signed-off-by: Nicolas Belouin <[email protected]>
>> ---
>> 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
>>
Nicolas
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
lmpx.com only provides a reader for public news (NNTP) servers. It is not
affiliated with the servers or forums shown here and is not responsible for
the content of articles, which is written by their respective authors.