tracehook: tracehook_tracer_task

This adds the tracehook_tracer_task() hook to consolidate all forms of
"Who is using ptrace on me?" logic.  This is used for "TracerPid:" in
/proc and for permission checks.  We also clean up the selinux code the
called an identical accessor.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 797d775e0354..0d6eb33597c6 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -80,6 +80,7 @@
 #include <linux/delayacct.h>
 #include <linux/seq_file.h>
 #include <linux/pid_namespace.h>
+#include <linux/tracehook.h>
 
 #include <asm/pgtable.h>
 #include <asm/processor.h>
@@ -168,8 +169,12 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
         rcu_read_lock();
         ppid = pid_alive(p) ?
                 task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
-        tpid = pid_alive(p) && p->ptrace ?
-                task_pid_nr_ns(rcu_dereference(p->parent), ns) : 0;
+        tpid = 0;
+        if (pid_alive(p)) {
+                struct task_struct *tracer = tracehook_tracer_task(p);
+                if (tracer)
+                        tpid = task_pid_nr_ns(tracer, ns);
+        }
         seq_printf(m,
                 "State:\t%s\n"
                 "Tgid:\t%d\n"