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-rw-r--r--include/linux/ptrace.h32
-rw-r--r--kernel/fork.c10
2 files changed, 39 insertions, 3 deletions
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 07d0df6..077904c 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -5,6 +5,7 @@
#include <linux/sched.h> /* For struct task_struct. */
#include <linux/err.h> /* for IS_ERR_VALUE */
#include <linux/bug.h> /* For BUG_ON. */
+#include <linux/pid_namespace.h> /* For task_active_pid_ns. */
#include <uapi/linux/ptrace.h>
/*
@@ -129,6 +130,37 @@ static inline void ptrace_event(int event, unsigned long message)
}
/**
+ * ptrace_event_pid - possibly stop for a ptrace event notification
+ * @event: %PTRACE_EVENT_* value to report
+ * @pid: process identifier for %PTRACE_GETEVENTMSG to return
+ *
+ * Check whether @event is enabled and, if so, report @event and @pid
+ * to the ptrace parent. @pid is reported as the pid_t seen from the
+ * the ptrace parent's pid namespace.
+ *
+ * Called without locks.
+ */
+static inline void ptrace_event_pid(int event, struct pid *pid)
+{
+ /*
+ * FIXME: There's a potential race if a ptracer in a different pid
+ * namespace than parent attaches between computing message below and
+ * when we acquire tasklist_lock in ptrace_stop(). If this happens,
+ * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
+ */
+ unsigned long message = 0;
+ struct pid_namespace *ns;
+
+ rcu_read_lock();
+ ns = task_active_pid_ns(rcu_dereference(current->parent));
+ if (ns)
+ message = pid_nr_ns(pid, ns);
+ rcu_read_unlock();
+
+ ptrace_event(event, message);
+}
+
+/**
* ptrace_init_task - initialize ptrace state for a new child
* @child: new child task
* @ptrace: true if child should be ptrace'd by parent's tracer
diff --git a/kernel/fork.c b/kernel/fork.c
index 0d53eb0..d2799d1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1606,10 +1606,12 @@ long do_fork(unsigned long clone_flags,
*/
if (!IS_ERR(p)) {
struct completion vfork;
+ struct pid *pid;
trace_sched_process_fork(current, p);
- nr = task_pid_vnr(p);
+ pid = get_task_pid(p, PIDTYPE_PID);
+ nr = pid_vnr(pid);
if (clone_flags & CLONE_PARENT_SETTID)
put_user(nr, parent_tidptr);
@@ -1624,12 +1626,14 @@ long do_fork(unsigned long clone_flags,
/* forking complete and child started to run, tell ptracer */
if (unlikely(trace))
- ptrace_event(trace, nr);
+ ptrace_event_pid(trace, pid);
if (clone_flags & CLONE_VFORK) {
if (!wait_for_vfork_done(p, &vfork))
- ptrace_event(PTRACE_EVENT_VFORK_DONE, nr);
+ ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
}
+
+ put_pid(pid);
} else {
nr = PTR_ERR(p);
}
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