linux-kernel - [PATCH AUTOSEL 4.19 16/56] seccomp: kill process instead of thread for unknown actions

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

Message-Id: <20201018192417.4055228-16-sashal@kernel.org>
Date:   Sun, 18 Oct 2020 15:23:37 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Rich Felker <dalias@...c.org>, Kees Cook <keescook@...omium.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.19 16/56] seccomp: kill process instead of thread for unknown actions

From: Rich Felker <dalias@...c.org>

[ Upstream commit 4d671d922d51907bc41f1f7f2dc737c928ae78fd ]

Asynchronous termination of a thread outside of the userspace thread
library's knowledge is an unsafe operation that leaves the process in
an inconsistent, corrupt, and possibly unrecoverable state. In order
to make new actions that may be added in the future safe on kernels
not aware of them, change the default action from
SECCOMP_RET_KILL_THREAD to SECCOMP_RET_KILL_PROCESS.

Signed-off-by: Rich Felker <dalias@...c.org>
Link: https://lore.kernel.org/r/20200829015609.GA32566@brightrain.aerifal.cx
[kees: Fixed up coredump selection logic to match]
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/seccomp.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 56e69203b6588..4b56c83eb3da9 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -745,7 +745,7 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
 	default:
 		seccomp_log(this_syscall, SIGSYS, action, true);
 		/* Dump core only if this is the last remaining thread. */
-		if (action == SECCOMP_RET_KILL_PROCESS ||
+		if (action != SECCOMP_RET_KILL_THREAD ||
 		    get_nr_threads(current) == 1) {
 			siginfo_t info;
 
@@ -755,10 +755,10 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
 			seccomp_init_siginfo(&info, this_syscall, data);
 			do_coredump(&info);
 		}
-		if (action == SECCOMP_RET_KILL_PROCESS)
-			do_group_exit(SIGSYS);
-		else
+		if (action == SECCOMP_RET_KILL_THREAD)
 			do_exit(SIGSYS);
+		else
+			do_group_exit(SIGSYS);
 	}
 
 	unreachable();
-- 
2.25.1