From patchwork Wed Jul 15 14:49:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adrian Reber X-Patchwork-Id: 11665623 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C2EAB13B1 for ; Wed, 15 Jul 2020 14:53:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A67DB206D5 for ; Wed, 15 Jul 2020 14:53:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GcBmqaBe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726963AbgGOOxP (ORCPT ); Wed, 15 Jul 2020 10:53:15 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:57768 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726960AbgGOOxO (ORCPT ); Wed, 15 Jul 2020 10:53:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594824793; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=d9gLBZH3xrp5bh9Hcfk99uaWsYU1ho/1zy2f3F6QJLA=; b=GcBmqaBeGaE6Xh0fJyDB73bl8SUWYodxOY7pC8VhbuREBT+v3lxrF+AwOfBhEaB/WkMOTf geJ+bGYn7p3aDpWphOffX6onYmB8410QFQ+06tmNvlT++WIgx5bkM2w9Y8NparXQ4WasBL PIp497SJHe0r+NGBcwJ4QNkoDKPpddQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-331-vxqMJMi2PhGPvdwM3iMhzQ-1; Wed, 15 Jul 2020 10:52:03 -0400 X-MC-Unique: vxqMJMi2PhGPvdwM3iMhzQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B5E7F800EB6; Wed, 15 Jul 2020 14:52:00 +0000 (UTC) Received: from dcbz.redhat.com (ovpn-114-113.ams2.redhat.com [10.36.114.113]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7CDEC60BF1; Wed, 15 Jul 2020 14:51:53 +0000 (UTC) From: Adrian Reber To: Christian Brauner , Eric Biederman , Pavel Emelyanov , Oleg Nesterov , Dmitry Safonov <0x7f454c46@gmail.com>, Andrei Vagin , Nicolas Viennot , =?utf-8?b?TWljaGHFgiBDxYJh?= =?utf-8?b?cGnFhHNraQ==?= , Kamil Yurtsever , Dirk Petersen , Christine Flood , Casey Schaufler Cc: Mike Rapoport , Radostin Stoyanov , Adrian Reber , Cyrill Gorcunov , Serge Hallyn , Stephen Smalley , Sargun Dhillon , Arnd Bergmann , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, selinux@vger.kernel.org, Eric Paris , Jann Horn , linux-fsdevel@vger.kernel.org Subject: [PATCH v5 6/6] selftests: add clone3() CAP_CHECKPOINT_RESTORE test Date: Wed, 15 Jul 2020 16:49:54 +0200 Message-Id: <20200715144954.1387760-7-areber@redhat.com> In-Reply-To: <20200715144954.1387760-1-areber@redhat.com> References: <20200715144954.1387760-1-areber@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: This adds a test that changes its UID, uses capabilities to get CAP_CHECKPOINT_RESTORE and uses clone3() with set_tid to create a process with a given PID as non-root. Signed-off-by: Adrian Reber Acked-by: Serge Hallyn --- tools/testing/selftests/clone3/Makefile | 4 +- .../clone3/clone3_cap_checkpoint_restore.c | 203 ++++++++++++++++++ 2 files changed, 206 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c diff --git a/tools/testing/selftests/clone3/Makefile b/tools/testing/selftests/clone3/Makefile index cf976c732906..ef7564cb7abe 100644 --- a/tools/testing/selftests/clone3/Makefile +++ b/tools/testing/selftests/clone3/Makefile @@ -1,6 +1,8 @@ # SPDX-License-Identifier: GPL-2.0 CFLAGS += -g -I../../../../usr/include/ +LDLIBS += -lcap -TEST_GEN_PROGS := clone3 clone3_clear_sighand clone3_set_tid +TEST_GEN_PROGS := clone3 clone3_clear_sighand clone3_set_tid \ + clone3_cap_checkpoint_restore include ../lib.mk diff --git a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c new file mode 100644 index 000000000000..2cc3d57b91f2 --- /dev/null +++ b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c @@ -0,0 +1,203 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Based on Christian Brauner's clone3() example. + * These tests are assuming to be running in the host's + * PID namespace. + */ + +/* capabilities related code based on selftests/bpf/test_verifier.c */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../kselftest.h" +#include "clone3_selftests.h" + +#ifndef MAX_PID_NS_LEVEL +#define MAX_PID_NS_LEVEL 32 +#endif + +static void child_exit(int ret) +{ + fflush(stdout); + fflush(stderr); + _exit(ret); +} + +static int call_clone3_set_tid(pid_t * set_tid, size_t set_tid_size) +{ + int status; + pid_t pid = -1; + + struct clone_args args = { + .exit_signal = SIGCHLD, + .set_tid = ptr_to_u64(set_tid), + .set_tid_size = set_tid_size, + }; + + pid = sys_clone3(&args, sizeof(struct clone_args)); + if (pid < 0) { + ksft_print_msg("%s - Failed to create new process\n", + strerror(errno)); + return -errno; + } + + if (pid == 0) { + int ret; + char tmp = 0; + + ksft_print_msg + ("I am the child, my PID is %d (expected %d)\n", + getpid(), set_tid[0]); + + if (set_tid[0] != getpid()) + child_exit(EXIT_FAILURE); + child_exit(EXIT_SUCCESS); + } + + ksft_print_msg("I am the parent (%d). My child's pid is %d\n", + getpid(), pid); + + if (waitpid(pid, &status, 0) < 0) { + ksft_print_msg("Child returned %s\n", strerror(errno)); + return -errno; + } + + if (!WIFEXITED(status)) + return -1; + + return WEXITSTATUS(status); +} + +static int test_clone3_set_tid(pid_t * set_tid, + size_t set_tid_size, int expected) +{ + int ret; + + ksft_print_msg("[%d] Trying clone3() with CLONE_SET_TID to %d\n", + getpid(), set_tid[0]); + ret = call_clone3_set_tid(set_tid, set_tid_size); + + ksft_print_msg + ("[%d] clone3() with CLONE_SET_TID %d says :%d - expected %d\n", + getpid(), set_tid[0], ret, expected); + if (ret != expected) { + ksft_test_result_fail + ("[%d] Result (%d) is different than expected (%d)\n", + getpid(), ret, expected); + return -1; + } + ksft_test_result_pass + ("[%d] Result (%d) matches expectation (%d)\n", getpid(), ret, + expected); + + return 0; +} + +struct libcap { + struct __user_cap_header_struct hdr; + struct __user_cap_data_struct data[2]; +}; + +static int set_capability() +{ + cap_value_t cap_values[] = { CAP_SETUID, CAP_SETGID }; + struct libcap *cap; + int ret = -1; + cap_t caps; + + caps = cap_get_proc(); + if (!caps) { + perror("cap_get_proc"); + return -1; + } + + /* Drop all capabilities */ + if (cap_clear(caps)) { + perror("cap_clear"); + goto out; + } + + cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_values, CAP_SET); + cap_set_flag(caps, CAP_PERMITTED, 2, cap_values, CAP_SET); + + cap = (struct libcap *) caps; + + /* 40 -> CAP_CHECKPOINT_RESTORE */ + cap->data[1].effective |= 1 << (40 - 32); + cap->data[1].permitted |= 1 << (40 - 32); + + if (cap_set_proc(caps)) { + perror("cap_set_proc"); + goto out; + } + ret = 0; +out: + if (cap_free(caps)) + perror("cap_free"); + return ret; +} + +int main(int argc, char *argv[]) +{ + pid_t pid; + int status; + int ret = 0; + pid_t set_tid[1]; + uid_t uid = getuid(); + + ksft_print_header(); + test_clone3_supported(); + ksft_set_plan(2); + + if (uid != 0) { + ksft_cnt.ksft_xskip = ksft_plan; + ksft_print_msg("Skipping all tests as non-root\n"); + return ksft_exit_pass(); + } + + memset(&set_tid, 0, sizeof(set_tid)); + + /* Find the current active PID */ + pid = fork(); + if (pid == 0) { + ksft_print_msg("Child has PID %d\n", getpid()); + child_exit(EXIT_SUCCESS); + } + if (waitpid(pid, &status, 0) < 0) + ksft_exit_fail_msg("Waiting for child %d failed", pid); + + /* After the child has finished, its PID should be free. */ + set_tid[0] = pid; + + if (set_capability()) + ksft_test_result_fail + ("Could not set CAP_CHECKPOINT_RESTORE\n"); + prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0); + /* This would fail without CAP_CHECKPOINT_RESTORE */ + setgid(1000); + setuid(1000); + set_tid[0] = pid; + ret |= test_clone3_set_tid(set_tid, 1, -EPERM); + if (set_capability()) + ksft_test_result_fail + ("Could not set CAP_CHECKPOINT_RESTORE\n"); + /* This should work as we have CAP_CHECKPOINT_RESTORE as non-root */ + ret |= test_clone3_set_tid(set_tid, 1, 0); + + return !ret ? ksft_exit_pass() : ksft_exit_fail(); +}