From patchwork Wed Feb 17 08:00:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Dmitry V. Levin" X-Patchwork-Id: 1441483 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=sparclinux-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4DgyBG74ryz9s1l for ; Thu, 18 Feb 2021 12:42:14 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230183AbhBRBmA (ORCPT ); Wed, 17 Feb 2021 20:42:00 -0500 Received: from vmicros1.altlinux.org ([194.107.17.57]:56218 "EHLO vmicros1.altlinux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230162AbhBRBl5 (ORCPT ); Wed, 17 Feb 2021 20:41:57 -0500 Received: from mua.local.altlinux.org (mua.local.altlinux.org [192.168.1.14]) by vmicros1.altlinux.org (Postfix) with ESMTP id 1BCF372C8B1; Thu, 18 Feb 2021 04:41:14 +0300 (MSK) Received: by mua.local.altlinux.org (Postfix, from userid 508) id 0D9777CC8A2; Thu, 18 Feb 2021 04:41:14 +0300 (MSK) Date: Wed, 17 Feb 2021 08:00:00 +0000 From: "Dmitry V. Levin" To: "David S. Miller" Cc: "Eric W. Biederman" , Alexey Gladkov , Gleb Fotengauer-Malinovskiy , Anatoly Pugachev , sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] sparc: make copy_thread honor pid namespaces Message-ID: <20210217080000.GA25861@altlinux.org> MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: sparclinux@vger.kernel.org On sparc, fork and clone syscalls have an unusual semantics of returning the pid of the parent process to the child process. Apparently, the implementation did not honor pid namespaces at all, so the child used to get the pid of its parent in the init namespace. This bug was found by strace test suite. Reproducer: $ gcc -Wall -O2 -xc - <<'EOF' #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include int main(void) { if (unshare(CLONE_NEWPID | CLONE_NEWUSER) < 0) err(1, "unshare"); int pid = syscall(__NR_fork); if (pid < 0) err(1, "fork"); fprintf(stderr, "current: %d, parent: %d, fork returned: %d\n", getpid(), getppid(), pid); int status; if (wait(&status) < 0) { if (errno == ECHILD) _exit(0); err(1, "wait"); } return !WIFEXITED(status) || WEXITSTATUS(status) != 0; } EOF $ sh -c ./a.out current: 10001, parent: 10000, fork returned: 10002 current: 1, parent: 0, fork returned: 10001 Cc: Eric W. Biederman Cc: stable@vger.kernel.org Signed-off-by: Dmitry V. Levin --- Although the fix seems to be obvious, I have no means to test it myself, so any help with the testing is much appreciated. arch/sparc/kernel/process_32.c | 2 +- arch/sparc/kernel/process_64.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c index a02363735915..7a89969befa8 100644 --- a/arch/sparc/kernel/process_32.c +++ b/arch/sparc/kernel/process_32.c @@ -368,7 +368,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, #endif /* Set the return value for the child. */ - childregs->u_regs[UREG_I0] = current->pid; + childregs->u_regs[UREG_I0] = task_pid_nr_ns(current, task_active_pid_ns(p)); childregs->u_regs[UREG_I1] = 1; /* Set the return value for the parent. */ diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c index 6f8c7822fc06..ec97217ab970 100644 --- a/arch/sparc/kernel/process_64.c +++ b/arch/sparc/kernel/process_64.c @@ -629,7 +629,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, t->utraps[0]++; /* Set the return value for the child. */ - t->kregs->u_regs[UREG_I0] = current->pid; + t->kregs->u_regs[UREG_I0] = task_pid_nr_ns(current, task_active_pid_ns(p)); t->kregs->u_regs[UREG_I1] = 1; /* Set the second return value for the parent. */