Re: [PATCH v22 12/23] LSM: Specify which LSM to display

John Johansen
2020-11-07T22:05:32Z

On 11/7/20 1:15 AM, Greg KH wrote:
> On Fri, Nov 06, 2020 at 04:20:43PM -0800, Casey Schaufler wrote:
>> On 11/5/2020 1:22 AM, Greg KH wrote:
>>> On Wed, Nov 04, 2020 at 03:41:03PM -0800, Casey Schaufler wrote:
>>>> Create a new entry "display" in the procfs attr directory for
>>>> controlling which LSM security information is displayed for a
>>>> process. A process can only read or write its own display value.
>>>>
>>>> The name of an active LSM that supplies hooks for
>>>> human readable data may be written to "display" to set the
>>>> value. The name of the LSM currently in use can be read from
>>>> "display". At this point there can only be one LSM capable
>>>> of display active. A helper function lsm_task_display() is
>>>> provided to get the display slot for a task_struct.
>>>>
>>>> Setting the "display" requires that all security modules using
>>>> setprocattr hooks allow the action. Each security module is
>>>> responsible for defining its policy.
>>>>
>>>> AppArmor hook provided by John Johansen <john.johansen@canonical.com>
>>>> SELinux hook provided by Stephen Smalley <sds@tycho.nsa.gov>
>>>>
>>>> Reviewed-by: Kees Cook <keescook@chromium.org>
>>>> Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
>>>> Acked-by: Paul Moore <paul@paul-moore.com>
>>>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>>>> Cc: linux-api@vger.kernel.org
>>>> ---
>>>> fs/proc/base.c | 1 +
>>>> include/linux/lsm_hooks.h | 17 +++
>>>> security/apparmor/include/apparmor.h | 3 +-
>>>> security/apparmor/lsm.c | 32 +++++
>>>> security/security.c | 169 ++++++++++++++++++++++++---
>>>> security/selinux/hooks.c | 11 ++
>>>> security/selinux/include/classmap.h | 2 +-
>>>> security/smack/smack_lsm.c | 7 ++
>>>> 8 files changed, 223 insertions(+), 19 deletions(-)
>>>>
>>>> diff --git a/fs/proc/base.c b/fs/proc/base.c
>>>> index 0f707003dda5..7432f24f0132 100644
>>>> --- a/fs/proc/base.c
>>>> +++ b/fs/proc/base.c
>>>> @@ -2806,6 +2806,7 @@ static const struct pid_entry attr_dir_stuff[] = {
>>>> ATTR(NULL, "fscreate", 0666),
>>>> ATTR(NULL, "keycreate", 0666),
>>>> ATTR(NULL, "sockcreate", 0666),
>>>> + ATTR(NULL, "display", 0666),
>>> That's a vague name, any chance it can be more descriptive?
>>
>> Sure. How about lsm_display, or display_lsm? I wouldn't say that
>> any of the files in /proc/*/attr have especially descriptive names,
>> but that's hardly an excuse.
>
> I still don't understand what "display" means in this context. Perhaps

its the LSM thats context is being displayed on the shared interface,
ie. /proc/*/attr/*

thinking about it more owner or even interface_owner might be a better
name

> documentation will help clear it up?
>

yeah this needs documented.

> thanks,
>
> greg k-h
>