On Thu, Jul 21, 2016 at 4:24 PM, John Stultz <[email protected]> wrote: > As requested, this patch checks the existing LSM hooks > task_getscheduler/task_setscheduler when reading or modifying > the task's timerslack value. > > Previous versions added new get/settimerslack LSM hooks, but > since they checked the same PROCESS__SET/GETSCHED values as > existing hooks, it was suggested we just use the existing ones. > > Cc: Kees Cook <[email protected]> > Cc: "Serge E. Hallyn" <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: Thomas Gleixner <[email protected]> > CC: Arjan van de Ven <[email protected]> > Cc: Oren Laadan <[email protected]> > Cc: Ruchi Kandoi <[email protected]> > Cc: Rom Lemarchand <[email protected]> > Cc: Todd Kjos <[email protected]> > Cc: Colin Cross <[email protected]> > Cc: Nick Kralevich <[email protected]> > Cc: Dmitry Shmidt <[email protected]> > Cc: Elliott Hughes <[email protected]> > Cc: James Morris <[email protected]> > Cc: Android Kernel Team <[email protected]> > Cc: [email protected] > Cc: [email protected] > Signed-off-by: John Stultz <[email protected]> > --- > v2: > * Initial swing at adding settimerslack LSM hook > v3: > * Fix current/p switchup bug noted by NickK > * Add gettimerslack hook suggested by NickK > v4: > * Dropped adding get/settimerslack LSM hooks, and > just reuse the get/setscheduler ones. > > fs/proc/base.c | 10 ++++++++++ > 1 file changed, 10 insertions(+)
For some reason I'm having a hard time finding patch 1/2 in the patchset, but this patch looks reasonable to me. We already have some LSM checking via the ptrace_may_access() call, but this adds some additional granularity which could be a good thing. Acked-by: Paul Moore <[email protected]> > diff --git a/fs/proc/base.c b/fs/proc/base.c > index c94abae..02f8389 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -2286,6 +2286,12 @@ static ssize_t timerslack_ns_write(struct file *file, > const char __user *buf, > goto out; > } > > + err = security_task_setscheduler(p); > + if (err) { > + count = err; > + goto out; > + } > + > task_lock(p); > if (slack_ns == 0) > p->timer_slack_ns = p->default_timer_slack_ns; > @@ -2314,6 +2320,10 @@ static int timerslack_ns_show(struct seq_file *m, void > *v) > goto out; > } > > + err = security_task_getscheduler(p); > + if (err) > + goto out; > + > task_lock(p); > seq_printf(m, "%llu\n", p->timer_slack_ns); > task_unlock(p); > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe > linux-security-module" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- paul moore www.paul-moore.com
