linux-kernel - [PATCHv4] ptrace: make former thread ID available via PTRACE_GETEVENTMSG after PTRACE_EVENT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <201106290413.39429.vda.linux@googlemail.com>
Date:	Wed, 29 Jun 2011 04:13:39 +0200
From:	Denys Vlasenko <vda.linux@...glemail.com>
To:	Oleg Nesterov <oleg@...hat.com>, Tejun Heo <tj@...nel.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCHv4] ptrace: make former thread ID available via PTRACE_GETEVENTMSG after PTRACE_EVENT_EXEC stop

Hi Oleg,

Please take a look at version 4 of this patch.

When multithreaded program execs under ptrace,
all traced threads report WIFEXITED status, except for
thread group leader and the thread which execs.

Unless tracer tracks thread group relationship between tracees,
which is a nontrivial task, it will not detect that
execed thread no longer exists.

This patch allows tracer to figure out which thread
performed this exec, by requesting PTRACE_GETEVENTMSG
in PTRACE_EVENT_EXEC stop.

Another, samller problem which is solved by this patch
is that tracer now can figure out which of the several
concurrent execs in multithreaded program succeeded.

Signed-off-by: Denys Vlasenko <vda.linux@...glemail.com>

-- 
vda


diff --git a/fs/exec.c b/fs/exec.c
index 8dca45b..55819be 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1357,6 +1357,7 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 	unsigned int depth = bprm->recursion_depth;
 	int try,retval;
 	struct linux_binfmt *fmt;
+	pid_t old_pid;
 
 	retval = security_bprm_check(bprm);
 	if (retval)
@@ -1370,6 +1371,11 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 	if (retval)
 		return retval;
 
+	/* Need to fetch pid before load_binary changes it */
+	rcu_read_lock();
+	old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
+	rcu_read_unlock();
+
 	retval = -ENOENT;
 	for (try=0; try<2; try++) {
 		read_lock(&binfmt_lock);
@@ -1389,7 +1395,8 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 			bprm->recursion_depth = depth;
 			if (retval >= 0) {
 				if (depth == 0)
-					ptrace_event(PTRACE_EVENT_EXEC, 0);
+					ptrace_event(PTRACE_EVENT_EXEC,
+							old_pid);
 				put_binfmt(fmt);
 				allow_write_access(bprm->file);
 				if (bprm->file)

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/