From patchwork Fri Jun 30 18:39:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Michal_Koutn=C3=BD?= X-Patchwork-Id: 13298674 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 911FDEB64D7 for ; Fri, 30 Jun 2023 18:39:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233024AbjF3SjV (ORCPT ); Fri, 30 Jun 2023 14:39:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45040 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229537AbjF3SjR (ORCPT ); Fri, 30 Jun 2023 14:39:17 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0A4F53C30; Fri, 30 Jun 2023 11:39:12 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 7C23F211CE; Fri, 30 Jun 2023 18:39:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1688150351; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/mkrwOQhXNXUI/w8q8/tfaaJ0AMF+TiZmf5ENkhiSpo=; b=UUqO4hoavU73XqgnT725k9l7mOYKqlhlUQYad9oWn1acVy+xl8ak21YdiLT3d8i2iJ3Ykh ku4OG8Pa3SzJXhKaXexajCS/5JtbOaNWyRIyrPBFMf91ezWfPsbGpEaVYSdPK3Uvw687AE Fyg1wkX0l/UFsHDa6so/bM7YDR4KOtw= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 53B06139FF; Fri, 30 Jun 2023 18:39:11 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id WFWoE08hn2QgbQAAMHmgww (envelope-from ); Fri, 30 Jun 2023 18:39:11 +0000 From: =?utf-8?q?Michal_Koutn=C3=BD?= To: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Waiman Long , Zefan Li , Tejun Heo , Johannes Weiner , Shuah Khan Subject: [PATCH v2 3/3] selftests: cgroup: Add cpuset migrations testcase Date: Fri, 30 Jun 2023 20:39:08 +0200 Message-ID: <20230630183908.32148-4-mkoutny@suse.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230630183908.32148-1-mkoutny@suse.com> References: <20230630183908.32148-1-mkoutny@suse.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Add a separate testfile to verify treating permissions when tasks are migrated on cgroup v2 hierarchy between cpuset cgroups. In accordance with v2 design, migration should be allowed based on delegation boundaries (i.e. cgroup.procs permissions) and does not depend on the migrated object (i.e. unprivileged process can migrate another process (even privileged) as long as it remains in the original dedicated scope). Signed-off-by: Michal Koutný --- MAINTAINERS | 1 + tools/testing/selftests/cgroup/.gitignore | 1 + tools/testing/selftests/cgroup/Makefile | 2 + tools/testing/selftests/cgroup/test_cpuset.c | 272 +++++++++++++++++++ 4 files changed, 276 insertions(+) create mode 100644 tools/testing/selftests/cgroup/test_cpuset.c diff --git a/MAINTAINERS b/MAINTAINERS index 03bec83944c4..5c55de000ee3 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -5260,6 +5260,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git F: Documentation/admin-guide/cgroup-v1/cpusets.rst F: include/linux/cpuset.h F: kernel/cgroup/cpuset.c +F: tools/testing/selftests/cgroup/test_cpuset.c F: tools/testing/selftests/cgroup/test_cpuset_prs.sh CONTROL GROUP - MEMORY RESOURCE CONTROLLER (MEMCG) diff --git a/tools/testing/selftests/cgroup/.gitignore b/tools/testing/selftests/cgroup/.gitignore index c4a57e69f749..8443a8d46a1c 100644 --- a/tools/testing/selftests/cgroup/.gitignore +++ b/tools/testing/selftests/cgroup/.gitignore @@ -5,4 +5,5 @@ test_freezer test_kmem test_kill test_cpu +test_cpuset wait_inotify diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile index 3d263747d2ad..dee0f013c7f4 100644 --- a/tools/testing/selftests/cgroup/Makefile +++ b/tools/testing/selftests/cgroup/Makefile @@ -12,6 +12,7 @@ TEST_GEN_PROGS += test_core TEST_GEN_PROGS += test_freezer TEST_GEN_PROGS += test_kill TEST_GEN_PROGS += test_cpu +TEST_GEN_PROGS += test_cpuset LOCAL_HDRS += $(selfdir)/clone3/clone3_selftests.h $(selfdir)/pidfd/pidfd.h @@ -23,3 +24,4 @@ $(OUTPUT)/test_core: cgroup_util.c $(OUTPUT)/test_freezer: cgroup_util.c $(OUTPUT)/test_kill: cgroup_util.c $(OUTPUT)/test_cpu: cgroup_util.c +$(OUTPUT)/test_cpuset: cgroup_util.c diff --git a/tools/testing/selftests/cgroup/test_cpuset.c b/tools/testing/selftests/cgroup/test_cpuset.c new file mode 100644 index 000000000000..976ec6f014d8 --- /dev/null +++ b/tools/testing/selftests/cgroup/test_cpuset.c @@ -0,0 +1,272 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include + +#include "../kselftest.h" +#include "cgroup_util.h" + +static int idle_process_fn(const char *cgroup, void *arg) +{ + (void)pause(); + return 0; +} + +static int do_migration_fn(const char *cgroup, void *arg) +{ + int object_pid = (int)(size_t)arg; + + if (setuid(TEST_UID)) + return EXIT_FAILURE; + + // XXX checking /proc/$pid/cgroup would be quicker than wait + if (cg_enter(cgroup, object_pid) || + cg_wait_for_proc_count(cgroup, 1)) + return EXIT_FAILURE; + + return EXIT_SUCCESS; +} + +static int do_controller_fn(const char *cgroup, void *arg) +{ + const char *child = cgroup; + const char *parent = arg; + + if (setuid(TEST_UID)) + return EXIT_FAILURE; + + if (!cg_read_strstr(child, "cgroup.controllers", "cpuset")) + return EXIT_FAILURE; + + if (cg_write(parent, "cgroup.subtree_control", "+cpuset")) + return EXIT_FAILURE; + + if (cg_read_strstr(child, "cgroup.controllers", "cpuset")) + return EXIT_FAILURE; + + if (cg_write(parent, "cgroup.subtree_control", "-cpuset")) + return EXIT_FAILURE; + + if (!cg_read_strstr(child, "cgroup.controllers", "cpuset")) + return EXIT_FAILURE; + + return EXIT_SUCCESS; +} + +/* + * Migrate a process between two sibling cgroups. + * The success should only depend on the parent cgroup permissions and not the + * migrated process itself (cpuset controller is in place because it uses + * security_task_setscheduler() in cgroup v1). + */ +static int test_cpuset_perms_object(const char *root, bool allow) +{ + char *parent = NULL, *child_src = NULL, *child_dst = NULL; + char *parent_procs = NULL, *child_src_procs = NULL, *child_dst_procs = NULL; + const uid_t test_euid = TEST_UID; + int object_pid = 0; + int ret = KSFT_FAIL; + + parent = cg_name(root, "cpuset_test_0"); + if (!parent) + goto cleanup; + parent_procs = cg_name(parent, "cgroup.procs"); + if (!parent_procs) + goto cleanup; + if (cg_create(parent)) + goto cleanup; + + child_src = cg_name(parent, "cpuset_test_1"); + if (!child_src) + goto cleanup; + child_src_procs = cg_name(child_src, "cgroup.procs"); + if (!child_src_procs) + goto cleanup; + if (cg_create(child_src)) + goto cleanup; + + child_dst = cg_name(parent, "cpuset_test_2"); + if (!child_dst) + goto cleanup; + child_dst_procs = cg_name(child_dst, "cgroup.procs"); + if (!child_dst_procs) + goto cleanup; + if (cg_create(child_dst)) + goto cleanup; + + if (cg_write(parent, "cgroup.subtree_control", "+cpuset")) + goto cleanup; + + if (cg_read_strstr(child_src, "cgroup.controllers", "cpuset") || + cg_read_strstr(child_dst, "cgroup.controllers", "cpuset")) + goto cleanup; + + /* Enable permissions along src->dst tree path */ + if (chown(child_src_procs, test_euid, -1) || + chown(child_dst_procs, test_euid, -1)) + goto cleanup; + + if (allow && chown(parent_procs, test_euid, -1)) + goto cleanup; + + /* Fork a privileged child as a test object */ + object_pid = cg_run_nowait(child_src, idle_process_fn, NULL); + if (object_pid < 0) + goto cleanup; + + /* Carry out migration in a child process that can drop all privileges + * (including capabilities), the main process must remain privileged for + * cleanup. + * Child process's cgroup is irrelevant but we place it into child_dst + * as hacky way to pass information about migration target to the child. + */ + if (allow ^ (cg_run(child_dst, do_migration_fn, (void *)(size_t)object_pid) == EXIT_SUCCESS)) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + if (object_pid > 0) { + (void)kill(object_pid, SIGTERM); + (void)clone_reap(object_pid, WEXITED); + } + + cg_destroy(child_dst); + free(child_dst_procs); + free(child_dst); + + cg_destroy(child_src); + free(child_src_procs); + free(child_src); + + cg_destroy(parent); + free(parent_procs); + free(parent); + + return ret; +} + +static int test_cpuset_perms_object_allow(const char *root) +{ + return test_cpuset_perms_object(root, true); +} + +static int test_cpuset_perms_object_deny(const char *root) +{ + return test_cpuset_perms_object(root, false); +} + +/* + * Migrate a process between parent and child implicitely + * Implicit migration happens when a controller is enabled/disabled. + * + */ +static int test_cpuset_perms_subtree(const char *root) +{ + char *parent = NULL, *child = NULL; + char *parent_procs = NULL, *parent_subctl = NULL, *child_procs = NULL; + const uid_t test_euid = TEST_UID; + int object_pid = 0; + int ret = KSFT_FAIL; + + parent = cg_name(root, "cpuset_test_0"); + if (!parent) + goto cleanup; + parent_procs = cg_name(parent, "cgroup.procs"); + if (!parent_procs) + goto cleanup; + parent_subctl = cg_name(parent, "cgroup.subtree_control"); + if (!parent_subctl) + goto cleanup; + if (cg_create(parent)) + goto cleanup; + + child = cg_name(parent, "cpuset_test_1"); + if (!child) + goto cleanup; + child_procs = cg_name(child, "cgroup.procs"); + if (!child_procs) + goto cleanup; + if (cg_create(child)) + goto cleanup; + + /* Enable permissions as in a delegated subtree */ + if (chown(parent_procs, test_euid, -1) || + chown(parent_subctl, test_euid, -1) || + chown(child_procs, test_euid, -1)) + goto cleanup; + + /* Put a privileged child in the subtree and modify controller state + * from an unprivileged process, the main process remains privileged + * for cleanup. + * The unprivileged child runs in subtree too to avoid parent and + * internal-node constraing violation. + */ + object_pid = cg_run_nowait(child, idle_process_fn, NULL); + if (object_pid < 0) + goto cleanup; + + if (cg_run(child, do_controller_fn, parent) != EXIT_SUCCESS) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + if (object_pid > 0) { + (void)kill(object_pid, SIGTERM); + (void)clone_reap(object_pid, WEXITED); + } + + cg_destroy(child); + free(child_procs); + free(child); + + cg_destroy(parent); + free(parent_subctl); + free(parent_procs); + free(parent); + + return ret; +} + + +#define T(x) { x, #x } +struct cpuset_test { + int (*fn)(const char *root); + const char *name; +} tests[] = { + T(test_cpuset_perms_object_allow), + T(test_cpuset_perms_object_deny), + T(test_cpuset_perms_subtree), +}; +#undef T + +int main(int argc, char *argv[]) +{ + char root[PATH_MAX]; + int i, ret = EXIT_SUCCESS; + + if (cg_find_unified_root(root, sizeof(root))) + ksft_exit_skip("cgroup v2 isn't mounted\n"); + + if (cg_read_strstr(root, "cgroup.subtree_control", "cpuset")) + if (cg_write(root, "cgroup.subtree_control", "+cpuset")) + ksft_exit_skip("Failed to set cpuset controller\n"); + + for (i = 0; i < ARRAY_SIZE(tests); i++) { + switch (tests[i].fn(root)) { + case KSFT_PASS: + ksft_test_result_pass("%s\n", tests[i].name); + break; + case KSFT_SKIP: + ksft_test_result_skip("%s\n", tests[i].name); + break; + default: + ret = EXIT_FAILURE; + ksft_test_result_fail("%s\n", tests[i].name); + break; + } + } + + return ret; +}