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

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(a)canonical.com&gt; > SELinux hook provided by Stephen Smalley <sds(a)tycho.nsa.gov&gt; > > Reviewed-by: Kees Cook <keescook(a)chromium.org&gt; > Acked-by: Stephen Smalley <sds(a)tycho.nsa.gov&gt; > Acked-by: Paul Moore <paul(a)paul-moore.com&gt; > Signed-off-by: Casey Schaufler <casey(a)schaufler-ca.com&gt; > Cc: linux-api(a)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?

And where is the Documentation/ABI/ entries for all of this, how does userspace know what these things are, and how to use them?

thanks, greg k-h