On Thu, Nov 17, 2016 at 9:05 AM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > When the flag PT_PTRACE_CAP was added the PTRACE_TRACEME path was > overlooked. This can result in incorrect behavior when an application > like strace traces an exec of a setuid executable. > > Further PT_PTRACE_CAP does not have enough information for making good > security decisions as it does not report which user namespace the > capability is in. This has already allowed one mistake through > insufficient granulariy. > > I found this issue when I was testing another corner case of exec and > discovered that I could not get strace to set PT_PTRACE_CAP even when > running strace as root with a full set of caps. > > This change fixes the above issue with strace allowing stracing as > root a setuid executable without disabling setuid. More fundamentaly > this change allows what is allowable at all times, by using the correct > information in it's decision. > > Cc: stable@xxxxxxxxxxxxxxx > Fixes: 4214e42f96d4 ("v2.4.9.11 -> v2.4.9.12") > Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> > --- > [...] > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 348f51b0ec92..8fe58255d219 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1656,6 +1656,7 @@ struct task_struct { > struct list_head cpu_timers[3]; > > /* process credentials */ > + const struct cred __rcu *ptracer_cred; /* Tracer's dredentials at attach */ Typo: credentials. -Kees -- Kees Cook Nexus Security -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html