From: Wang Chao <wang.chao@cn.fujitsu.com>
Date: Thu, 16 Sep 2010 03:20:56 +0000 (+0800)
Subject: Do not trace children cloned with CLONE_UNTRACED flag
X-Git-Tag: v4.6~79
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e636c8516567642ed1ef0b281739f90650a6e109;p=strace

Do not trace children cloned with CLONE_UNTRACED flag

If clone is called with flag CLONE_UNTRACED, to be consistent with
option PTRACE_O_TRACECLONE, we should not set CLONE_PTRACE flag on
its arguments.

* process.c [LINUX] (internal_fork): Check the syscall and arguments.

Signed-off-by: Wang Chao <wang.chao@cn.fujitsu.com>
---

diff --git a/process.c b/process.c
index 8999fc67..2366d1f3 100644
--- a/process.c
+++ b/process.c
@@ -796,8 +796,17 @@ int
 internal_fork(struct tcb *tcp)
 {
 	if (entering(tcp)) {
+		tcp->flags &= ~TCB_FOLLOWFORK;
 		if (!followfork)
 			return 0;
+		/*
+		 * In occasion of using PTRACE_O_TRACECLONE, we won't see the
+		 * new child if clone is called with flag CLONE_UNTRACED, so
+		 * we keep the same logic with that option and don't trace it.
+		 */
+		if ((sysent[tcp->scno].sys_func == sys_clone) &&
+		    (tcp->u_arg[ARG_FLAGS] & CLONE_UNTRACED))
+			return 0;
 		fork_tcb(tcp);
 		if (setbpt(tcp) < 0)
 			return 0;