From patchwork Mon Feb 7 12:17:59 2022 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: 540657 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 61BB8C43217 for ; Mon, 7 Feb 2022 12:32:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382630AbiBGM20 (ORCPT ); Mon, 7 Feb 2022 07:28:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1382754AbiBGMYW (ORCPT ); Mon, 7 Feb 2022 07:24:22 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E0E2C002B4E; Mon, 7 Feb 2022 04:18:14 -0800 (PST) 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 262E8210FA; Mon, 7 Feb 2022 12:18:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1644236293; 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=WP6Xgo2ws98hPpXKeUU962VqHQ+2ksGNpkLhWTonht4=; b=TGINR8F84BeIkQgoA51gSRY3TQArk02/ttVciZuSUTaE915VzbI2t5jJbBPIy7qcRntcI8 Y+Lgxh5qk9zh+ztIJwYwFqwMHqJpiQIC3MdiFPcJEZbx5mRbfsl2oS0DgxqXR76IRO88o/ 14AYuFnOo3RVUkVt/oFbsuSTrFiN5g8= 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 0472B13BE6; Mon, 7 Feb 2022 12:18:13 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id qGCSAAUOAWLMegAAMHmgww (envelope-from ); Mon, 07 Feb 2022 12:18:13 +0000 From: =?utf-8?q?Michal_Koutn=C3=BD?= To: Eric Biederman , Alexey Gladkov Cc: Kees Cook , Shuah Khan , Christian Brauner , Solar Designer , Ran Xiaokai , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Linux Containers Subject: [RFC PATCH 5/6] selftests: Challenge RLIMIT_NPROC in user namespaces Date: Mon, 7 Feb 2022 13:17:59 +0100 Message-Id: <20220207121800.5079-6-mkoutny@suse.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220207121800.5079-1-mkoutny@suse.com> References: <20220207121800.5079-1-mkoutny@suse.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org The services are started in descendant user namepaces, each of them should honor the RLIMIT_NPROC that's passed during user namespace creation. main [user_ns_0] ` service [user_ns_1] ` worker 1 ` worker 2 ... ` worker k ... ` service [user_ns_n] ` worker 1 ` worker 2 ... ` worker k Test uses explicit synchronization, to make sure original parent's limit does not interfere with descendants. Signed-off-by: Michal Koutný --- .../selftests/rlimits/rlimits-per-userns.c | 154 ++++++++++++++---- 1 file changed, 125 insertions(+), 29 deletions(-) diff --git a/tools/testing/selftests/rlimits/rlimits-per-userns.c b/tools/testing/selftests/rlimits/rlimits-per-userns.c index 26dc949e93ea..54c1b345e42b 100644 --- a/tools/testing/selftests/rlimits/rlimits-per-userns.c +++ b/tools/testing/selftests/rlimits/rlimits-per-userns.c @@ -9,7 +9,9 @@ #include #include #include +#include +#include #include #include #include @@ -21,38 +23,74 @@ #include #include -#define NR_CHILDS 2 +#define THE_LIMIT 4 +#define NR_CHILDREN 5 + +static_assert(NR_CHILDREN >= THE_LIMIT-1, "Need slots for limit-1 children."); static char *service_prog; static uid_t user = 60000; static uid_t group = 60000; +static struct rlimit saved_limit; + +/* Two uses: main and service */ +static pid_t child[NR_CHILDREN]; +static pid_t pid; static void setrlimit_nproc(rlim_t n) { - pid_t pid = getpid(); struct rlimit limit = { .rlim_cur = n, .rlim_max = n }; - - warnx("(pid=%d): Setting RLIMIT_NPROC=%ld", pid, n); + if (getrlimit(RLIMIT_NPROC, &saved_limit) < 0) + err(EXIT_FAILURE, "(pid=%d): getrlimit(RLIMIT_NPROC)", pid); if (setrlimit(RLIMIT_NPROC, &limit) < 0) err(EXIT_FAILURE, "(pid=%d): setrlimit(RLIMIT_NPROC)", pid); + + warnx("(pid=%d): Set RLIMIT_NPROC=%ld", pid, n); +} + +static void restore_rlimit_nproc(void) +{ + if (setrlimit(RLIMIT_NPROC, &saved_limit) < 0) + err(EXIT_FAILURE, "(pid=%d): setrlimit(RLIMIT_NPROC, saved)", pid); + warnx("(pid=%d) Restored RLIMIT_NPROC", pid); } -static pid_t fork_child(void) +enum msg_sync { + UNSHARE, + RLIMIT_RESTORE, +}; + +static void sync_notify(int fd, enum msg_sync m) { - pid_t pid = fork(); + char tmp = m; + + if (write(fd, &tmp, 1) < 0) + warnx("(pid=%d): failed sync-write", pid); +} - if (pid < 0) +static void sync_wait(int fd, enum msg_sync m) +{ + char tmp; + + if (read(fd, &tmp, 1) < 0) + warnx("(pid=%d): failed sync-read", pid); +} + +static pid_t fork_child(int control_fd) +{ + pid_t new_pid = fork(); + + if (new_pid < 0) err(EXIT_FAILURE, "fork"); - if (pid > 0) - return pid; + if (new_pid > 0) + return new_pid; pid = getpid(); - warnx("(pid=%d): New process starting ...", pid); if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0) @@ -73,6 +111,9 @@ static pid_t fork_child(void) if (unshare(CLONE_NEWUSER) < 0) err(EXIT_FAILURE, "unshare(CLONE_NEWUSER)"); + sync_notify(control_fd, UNSHARE); + sync_wait(control_fd, RLIMIT_RESTORE); + char *const argv[] = { "service", NULL }; char *const envp[] = { "I_AM_SERVICE=1", NULL }; @@ -82,37 +123,92 @@ static pid_t fork_child(void) err(EXIT_FAILURE, "(pid=%d): execve", pid); } +static void run_service(void) +{ + size_t i; + int ret = EXIT_SUCCESS; + struct rlimit limit; + char user_ns[PATH_MAX]; + + if (getrlimit(RLIMIT_NPROC, &limit) < 0) + err(EXIT_FAILURE, "(pid=%d) failed getrlimit", pid); + if (readlink("/proc/self/ns/user", user_ns, PATH_MAX) < 0) + err(EXIT_FAILURE, "(pid=%d) failed readlink", pid); + + warnx("(pid=%d) Service instance attempts %i children, limit %lu:%lu, ns=%s", + pid, THE_LIMIT, limit.rlim_cur, limit.rlim_max, user_ns); + + /* test rlimit inside the service, effectively THE_LIMIT-1 becaue of service itself */ + for (i = 0; i < THE_LIMIT; i++) { + child[i] = fork(); + if (child[i] == 0) { + /* service child */ + pause(); + exit(EXIT_SUCCESS); + } + if (child[i] < 0) { + warnx("(pid=%d) service fork %lu failed, errno = %i", pid, i+1, errno); + if (!(i == THE_LIMIT-1 && errno == EAGAIN)) + ret = EXIT_FAILURE; + } else if (i == THE_LIMIT-1) { + warnx("(pid=%d) RLIMIT_NPROC not honored", pid); + ret = EXIT_FAILURE; + } + } + + /* service cleanup */ + for (i = 0; i < THE_LIMIT; i++) + if (child[i] > 0) + kill(child[i], SIGUSR1); + + for (i = 0; i < THE_LIMIT; i++) + if (child[i] > 0) + waitpid(child[i], NULL, WNOHANG); + + if (ret) + exit(ret); + pause(); +} + int main(int argc, char **argv) { size_t i; - pid_t child[NR_CHILDS]; - int wstatus[NR_CHILDS]; - int childs = NR_CHILDS; - pid_t pid; + int control_fd[NR_CHILDREN]; + int wstatus[NR_CHILDREN]; + int children = NR_CHILDREN; + int sockets[2]; + + pid = getpid(); if (getenv("I_AM_SERVICE")) { - pause(); - exit(EXIT_SUCCESS); + run_service(); + exit(EXIT_FAILURE); } service_prog = argv[0]; - pid = getpid(); warnx("(pid=%d) Starting testcase", pid); - /* - * This rlimit is not a problem for root because it can be exceeded. - */ - setrlimit_nproc(1); - - for (i = 0; i < NR_CHILDS; i++) { - child[i] = fork_child(); + setrlimit_nproc(THE_LIMIT); + for (i = 0; i < NR_CHILDREN; i++) { + if (socketpair(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0, sockets) < 0) + err(EXIT_FAILURE, "(pid=%d) socketpair failed", pid); + control_fd[i] = sockets[0]; + child[i] = fork_child(sockets[1]); wstatus[i] = 0; + } + + for (i = 0; i < NR_CHILDREN; i++) + sync_wait(control_fd[i], UNSHARE); + restore_rlimit_nproc(); + + for (i = 0; i < NR_CHILDREN; i++) { + sync_notify(control_fd[i], RLIMIT_RESTORE); usleep(250000); } while (1) { - for (i = 0; i < NR_CHILDS; i++) { + for (i = 0; i < NR_CHILDREN; i++) { if (child[i] <= 0) continue; @@ -126,22 +222,22 @@ int main(int argc, char **argv) warn("(pid=%d): waitpid(%d)", pid, child[i]); child[i] *= -1; - childs -= 1; + children -= 1; } - if (!childs) + if (!children) break; usleep(250000); - for (i = 0; i < NR_CHILDS; i++) { + for (i = 0; i < NR_CHILDREN; i++) { if (child[i] <= 0) continue; kill(child[i], SIGUSR1); } } - for (i = 0; i < NR_CHILDS; i++) { + for (i = 0; i < NR_CHILDREN; i++) { if (WIFEXITED(wstatus[i])) warnx("(pid=%d): pid %d exited, status=%d", pid, -child[i], WEXITSTATUS(wstatus[i]));