From patchwork Fri Sep 30 16:01:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?G=C3=BCnther_Noack?= X-Patchwork-Id: 12995733 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 D790BC433F5 for ; Fri, 30 Sep 2022 16:02:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231934AbiI3QCx (ORCPT ); Fri, 30 Sep 2022 12:02:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231777AbiI3QCS (ORCPT ); Fri, 30 Sep 2022 12:02:18 -0400 Received: from mail-ed1-x534.google.com (mail-ed1-x534.google.com [IPv6:2a00:1450:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A08911B0512; Fri, 30 Sep 2022 09:02:15 -0700 (PDT) Received: by mail-ed1-x534.google.com with SMTP id y8so6557537edc.10; Fri, 30 Sep 2022 09:02:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date; bh=6srsNO+PnD44pD9cuu4iqeCet2frHPF+z/NrQzZBp+E=; b=akMEACoKhQNR86trTa3gJuFenczxFAfJopi3gQz8C26bu8pgpl8TBH4piFfUpLPiCG ZjMT3it5aYF6KMt132fEEFUqF7TGkI3aWRZzB6153YcbK6OTIH2Xci49s1pjNr1Sp2VO VqD00Zo5Np8tO7zjDZ8vxuEK3OHciU1eeux37VgYyEOdJjMUDqmSzbJ4xYE1HrnVm4y3 owr8bt7IWzXvbriXCWioJ22QqKI5OZ3e0pp614qC4DPvalW+/VRWBuS8C1o8I3CN6eJM Y/2GmuflSoJtASmpXnVDfDzrma+noSUE4X3T3PyuLTwphPdEg54RUYi5FofswDby09c5 He+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=6srsNO+PnD44pD9cuu4iqeCet2frHPF+z/NrQzZBp+E=; b=wkWZnxOUqn47YqwXeJLWE5d5QifFqKYD/ZulahiPmdgeoJRhM+/ygu+WpBVOvP/3P1 DFFsl6TXypRLzkbcGG5PfteI+ofjkw7bOqBT8oC6JCck1R04AuvB1G23rJU/uz2gwSR/ q0Wzc7vJzC7C6AnLKyVMEdUUgZ2u2N2yQ6+GwXbHVhztSkFT+iDZGufCj/DbXCMTvGCU Ppn5VFvDppTNCMz8KlC3ATtWWrPyzRfcGVcgBjsVD/nDPFKEYcZlNDEI/DkY6tsNGxhA M68leabfQ8m+oZrkWaikzbRmFJVm/rluZi7FQdxh2AHshysE2PD1EOB9Mfj5D4ZZT5Mj e4yg== X-Gm-Message-State: ACrzQf0Pf7V1QN5D/CByNaJOa594djen0ErGKC5kp67XhYFY4StFxV0g 0KfJwd/9vbR8h2fuwvMi4OkQZphEj5A= X-Google-Smtp-Source: AMsMyM6mO2TLigGKg2JkStpo3szvUkfM86c6hg1G+snKqedez1OhvCSTVKrK792UdTw9abe3Gg3Raw== X-Received: by 2002:aa7:cb0b:0:b0:456:e744:79e5 with SMTP id s11-20020aa7cb0b000000b00456e74479e5mr8468292edt.191.1664553733876; Fri, 30 Sep 2022 09:02:13 -0700 (PDT) Received: from nuc.i.gnoack.org ([2a02:168:633b:1:1e69:7aff:fe05:97e6]) by smtp.gmail.com with ESMTPSA id f18-20020a05640214d200b004588ef795easm927583edx.34.2022.09.30.09.02.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Sep 2022 09:02:13 -0700 (PDT) From: =?utf-8?q?G=C3=BCnther_Noack?= To: linux-security-module@vger.kernel.org Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , James Morris , Paul Moore , "Serge E . Hallyn" , linux-fsdevel@vger.kernel.org, Konstantin Meskhidze , =?utf-8?q?G=C3=BCnt?= =?utf-8?q?her_Noack?= Subject: [PATCH v7 5/7] selftests/landlock: Test FD passing from a Landlock-restricted to an unrestricted process Date: Fri, 30 Sep 2022 18:01:42 +0200 Message-Id: <20220930160144.141504-6-gnoack3000@gmail.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220930160144.141504-1-gnoack3000@gmail.com> References: <20220930160144.141504-1-gnoack3000@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: A file descriptor created in a restricted process carries Landlock restrictions with it which will apply even if the same opened file is used from an unrestricted process. This change extracts suitable FD-passing helpers from base_test.c and moves them to common.h. We use the fixture variants from the ftruncate fixture to exercise the same scenarios as in the open_and_ftruncate test, but doing the Landlock restriction and open() in a different process than the ftruncate() call. Signed-off-by: Günther Noack --- tools/testing/selftests/landlock/base_test.c | 36 +---------- tools/testing/selftests/landlock/common.h | 67 ++++++++++++++++++++ tools/testing/selftests/landlock/fs_test.c | 62 ++++++++++++++++++ 3 files changed, 132 insertions(+), 33 deletions(-) diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c index 72cdae277b02..6d1b6eedb432 100644 --- a/tools/testing/selftests/landlock/base_test.c +++ b/tools/testing/selftests/landlock/base_test.c @@ -263,23 +263,6 @@ TEST(ruleset_fd_transfer) .allowed_access = LANDLOCK_ACCESS_FS_READ_DIR, }; int ruleset_fd_tx, dir_fd; - union { - /* Aligned ancillary data buffer. */ - char buf[CMSG_SPACE(sizeof(ruleset_fd_tx))]; - struct cmsghdr _align; - } cmsg_tx = {}; - char data_tx = '.'; - struct iovec io = { - .iov_base = &data_tx, - .iov_len = sizeof(data_tx), - }; - struct msghdr msg = { - .msg_iov = &io, - .msg_iovlen = 1, - .msg_control = &cmsg_tx.buf, - .msg_controllen = sizeof(cmsg_tx.buf), - }; - struct cmsghdr *cmsg; int socket_fds[2]; pid_t child; int status; @@ -298,33 +281,20 @@ TEST(ruleset_fd_transfer) &path_beneath_attr, 0)); ASSERT_EQ(0, close(path_beneath_attr.parent_fd)); - cmsg = CMSG_FIRSTHDR(&msg); - ASSERT_NE(NULL, cmsg); - cmsg->cmsg_len = CMSG_LEN(sizeof(ruleset_fd_tx)); - cmsg->cmsg_level = SOL_SOCKET; - cmsg->cmsg_type = SCM_RIGHTS; - memcpy(CMSG_DATA(cmsg), &ruleset_fd_tx, sizeof(ruleset_fd_tx)); - /* Sends the ruleset FD over a socketpair and then close it. */ ASSERT_EQ(0, socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, socket_fds)); - ASSERT_EQ(sizeof(data_tx), sendmsg(socket_fds[0], &msg, 0)); + ASSERT_EQ(0, send_fd(socket_fds[0], ruleset_fd_tx)); ASSERT_EQ(0, close(socket_fds[0])); ASSERT_EQ(0, close(ruleset_fd_tx)); child = fork(); ASSERT_LE(0, child); if (child == 0) { - int ruleset_fd_rx; + int ruleset_fd_rx = recv_fd(socket_fds[1]); - *(char *)msg.msg_iov->iov_base = '\0'; - ASSERT_EQ(sizeof(data_tx), - recvmsg(socket_fds[1], &msg, MSG_CMSG_CLOEXEC)); - ASSERT_EQ('.', *(char *)msg.msg_iov->iov_base); + ASSERT_LE(0, ruleset_fd_rx); ASSERT_EQ(0, close(socket_fds[1])); - cmsg = CMSG_FIRSTHDR(&msg); - ASSERT_EQ(cmsg->cmsg_len, CMSG_LEN(sizeof(ruleset_fd_tx))); - memcpy(&ruleset_fd_rx, CMSG_DATA(cmsg), sizeof(ruleset_fd_tx)); /* Enforces the received ruleset on the child. */ ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)); diff --git a/tools/testing/selftests/landlock/common.h b/tools/testing/selftests/landlock/common.h index 7ba18eb23783..8ec8971e9580 100644 --- a/tools/testing/selftests/landlock/common.h +++ b/tools/testing/selftests/landlock/common.h @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -187,3 +188,69 @@ clear_cap(struct __test_metadata *const _metadata, const cap_value_t caps) { _effective_cap(_metadata, caps, CAP_CLEAR); } + +/* Receives an FD from a UNIX socket. Returns the received FD, -1 on error. */ +__maybe_unused static int recv_fd(int usock) +{ + int fd_rx; + union { + /* Aligned ancillary data buffer. */ + char buf[CMSG_SPACE(sizeof(fd_rx))]; + struct cmsghdr _align; + } cmsg_rx = {}; + char data = '\0'; + struct iovec io = { + .iov_base = &data, + .iov_len = sizeof(data), + }; + struct msghdr msg = { + .msg_iov = &io, + .msg_iovlen = 1, + .msg_control = &cmsg_rx.buf, + .msg_controllen = sizeof(cmsg_rx.buf), + }; + struct cmsghdr *cmsg; + int res; + + res = recvmsg(usock, &msg, MSG_CMSG_CLOEXEC); + if (res < 0) + return -1; + + cmsg = CMSG_FIRSTHDR(&msg); + if (cmsg->cmsg_len != CMSG_LEN(sizeof(fd_rx))) + return -1; + + memcpy(&fd_rx, CMSG_DATA(cmsg), sizeof(fd_rx)); + return fd_rx; +} + +/* Sends an FD on a UNIX socket. Returns 0 on success or -1 on error. */ +__maybe_unused static int send_fd(int usock, int fd_tx) +{ + union { + /* Aligned ancillary data buffer. */ + char buf[CMSG_SPACE(sizeof(fd_tx))]; + struct cmsghdr _align; + } cmsg_tx = {}; + char data_tx = '.'; + struct iovec io = { + .iov_base = &data_tx, + .iov_len = sizeof(data_tx), + }; + struct msghdr msg = { + .msg_iov = &io, + .msg_iovlen = 1, + .msg_control = &cmsg_tx.buf, + .msg_controllen = sizeof(cmsg_tx.buf), + }; + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + + cmsg->cmsg_len = CMSG_LEN(sizeof(fd_tx)); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + memcpy(CMSG_DATA(cmsg), &fd_tx, sizeof(fd_tx)); + + if (sendmsg(usock, &msg, 0) < 0) + return -1; + return 0; +} diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c index 308f6f36e8c0..93ed80a25a74 100644 --- a/tools/testing/selftests/landlock/fs_test.c +++ b/tools/testing/selftests/landlock/fs_test.c @@ -3541,6 +3541,68 @@ TEST_F_FORK(ftruncate, open_and_ftruncate) } } +TEST_F_FORK(ftruncate, open_and_ftruncate_in_different_processes) +{ + int child, fd, status; + int socket_fds[2]; + + ASSERT_EQ(0, socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, + socket_fds)); + + child = fork(); + ASSERT_LE(0, child); + if (child == 0) { + /* + * Enable Landlock in the child process, open a file descriptor + * where truncation is forbidden and send it to the + * non-landlocked parent process. + */ + const char *const path = file1_s1d1; + const struct rule rules[] = { + { + .path = path, + .access = variant->permitted, + }, + {}, + }; + int fd, ruleset_fd; + + /* Enable Landlock. */ + ruleset_fd = create_ruleset(_metadata, variant->handled, rules); + ASSERT_LE(0, ruleset_fd); + enforce_ruleset(_metadata, ruleset_fd); + ASSERT_EQ(0, close(ruleset_fd)); + + fd = open(path, O_WRONLY); + ASSERT_EQ(variant->expected_open_result, (fd < 0 ? errno : 0)); + + if (fd >= 0) { + ASSERT_EQ(0, send_fd(socket_fds[0], fd)); + ASSERT_EQ(0, close(fd)); + } + + ASSERT_EQ(0, close(socket_fds[0])); + + _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE); + } + + if (variant->expected_open_result == 0) { + fd = recv_fd(socket_fds[1]); + ASSERT_LE(0, fd); + + EXPECT_EQ(variant->expected_ftruncate_result, + test_ftruncate(fd)); + ASSERT_EQ(0, close(fd)); + } + + ASSERT_EQ(child, waitpid(child, &status, 0)); + ASSERT_EQ(1, WIFEXITED(status)); + ASSERT_EQ(EXIT_SUCCESS, WEXITSTATUS(status)); + + ASSERT_EQ(0, close(socket_fds[0])); + ASSERT_EQ(0, close(socket_fds[1])); +} + /* clang-format off */ FIXTURE(layout1_bind) {}; /* clang-format on */