From 0d094efeb1e98010c6b99923f1eb7e17bf1e3a74 Mon Sep 17 00:00:00 2001
From: Roland McGrath <roland@redhat.com>
Date: Fri, 25 Jul 2008 19:45:49 -0700
Subject: 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>
---
 fs/proc/array.c |  9 +++++++--
 fs/proc/base.c  | 13 +++++++++----
 2 files changed, 16 insertions(+), 6 deletions(-)

(limited to 'fs/proc')

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 797d775e035..0d6eb33597c 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"
diff --git a/fs/proc/base.c b/fs/proc/base.c
index a891fe4cb43..4b74dba69a6 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -69,6 +69,7 @@
 #include <linux/mount.h>
 #include <linux/security.h>
 #include <linux/ptrace.h>
+#include <linux/tracehook.h>
 #include <linux/cgroup.h>
 #include <linux/cpuset.h>
 #include <linux/audit.h>
@@ -231,10 +232,14 @@ static int check_mem_permission(struct task_struct *task)
 	 * If current is actively ptrace'ing, and would also be
 	 * permitted to freshly attach with ptrace now, permit it.
 	 */
-	if (task->parent == current && (task->ptrace & PT_PTRACED) &&
-	    task_is_stopped_or_traced(task) &&
-	    ptrace_may_access(task, PTRACE_MODE_ATTACH))
-		return 0;
+	if (task_is_stopped_or_traced(task)) {
+		int match;
+		rcu_read_lock();
+		match = (tracehook_tracer_task(task) == current);
+		rcu_read_unlock();
+		if (match && ptrace_may_access(task, PTRACE_MODE_ATTACH))
+			return 0;
+	}
 
 	/*
 	 * Noone else is allowed.
-- 
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