From mboxrd@z Thu Jan 1 00:00:00 1970 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 67D42C433F5 for ; Sat, 8 Oct 2022 08:25:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229623AbiJHIZp (ORCPT ); Sat, 8 Oct 2022 04:25:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229505AbiJHIZn (ORCPT ); Sat, 8 Oct 2022 04:25:43 -0400 Received: from mail-ed1-x52a.google.com (mail-ed1-x52a.google.com [IPv6:2a00:1450:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 698801CB27; Sat, 8 Oct 2022 01:25:42 -0700 (PDT) Received: by mail-ed1-x52a.google.com with SMTP id z3so8797955edc.10; Sat, 08 Oct 2022 01:25:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=5wJQn5HejSWqpqDhl29mgQlrlsWCcpu9EfQRqAkO9fI=; b=FauiGavHGiukhfEOrC5nm1iGLHMs6gycvmq09foH2whr7GltkF6u4t7zTmwXGcETXL nEminySBatZ2hNYq51rLnd7+cjRsrnjqeTGAJI85j+HmjQA85Iu6aZXN81aMmkvKd5pG UJp/0sLCYflX2FNKmMMR2QZ+6Lz8fOyvVtsDPTExzGtgG1n34HuxiE7aXp9UG0AkZFfM V0jw95TpPPVoY7tloVJq7cdQgMpNhzcpfMrBIGlXGWDaO/IvlGlQG+nO8aVgEWbUwQ2T rralF2qNcdiElJprAvid3dC+uoTjF4KVP1CIk62I3mor97iLO7oXYEUeQNlJf4C8m2ei jFFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=5wJQn5HejSWqpqDhl29mgQlrlsWCcpu9EfQRqAkO9fI=; b=IBZWavcbJt8d7U1ORP8TYxwnEhVvaIujEJ7Q0L0rrUuzhbD8zIkFz2JwUDRQoyw1jR ntOT5Vi4cd/una4Uqf8U4ePhmwga+VBK6U+2a01tsZOOLXd3x1X16bd4c+r5TuVIwSwN Ome3E6FAkGTf1V3h4inHtKXZOAGu6Zm5FfETA1hw4nD2llYcQtRMHvMa7te/IST1PxAk h3oFhonXZTV8gwZ8h/0Tx6cVZbwGkrJygcP3M3bHn0uhPCeYoV+w0ZptApR5nT+mHhyW 6YnBXPiYatM3o3zEbleF2jS8bnZNFxB3y9iax/+3DfptPsTWuhnKHTaoJVMIo1YfU+l1 TKIQ== X-Gm-Message-State: ACrzQf3uyfRIkPflbphzEbc4YIYTbPGqeYN28yIdQGsxBckOXlIy/Guw 6/dLY+hHxH053iByfYOpa3c= X-Google-Smtp-Source: AMsMyM5OHouT75o6Bnaz9RxfzCJZfh7XhaeSGXdBmeUF+y5OxqbNMDdqdhsYaTs0gwhrhyE6yTv70w== X-Received: by 2002:a05:6402:4307:b0:459:4c7b:e843 with SMTP id m7-20020a056402430700b004594c7be843mr7894549edc.153.1665217540848; Sat, 08 Oct 2022 01:25:40 -0700 (PDT) Received: from nuc ([2a02:168:633b:1:1e69:7aff:fe05:97e6]) by smtp.gmail.com with ESMTPSA id bx10-20020a0564020b4a00b00456cbd8c65bsm3078607edb.6.2022.10.08.01.25.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Oct 2022 01:25:40 -0700 (PDT) Date: Sat, 8 Oct 2022 10:25:38 +0200 From: =?iso-8859-1?Q?G=FCnther?= Noack To: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= Cc: linux-security-module@vger.kernel.org, James Morris , Paul Moore , "Serge E . Hallyn" , linux-fsdevel@vger.kernel.org, Konstantin Meskhidze Subject: Re: [PATCH v8 7/9] selftests/landlock: Test FD passing from a Landlock-restricted to an unrestricted process Message-ID: References: <20221001154908.49665-1-gnoack3000@gmail.com> <20221001154908.49665-8-gnoack3000@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Oct 05, 2022 at 08:57:12PM +0200, Mickaël Salaün wrote: > Thanks for this refactoring. > > We need a shorter subject though. ;) Done, changed to: "selftests/landlock: Test FD passing from restricted to unrestricted processes" > On 01/10/2022 17:49, Günther Noack wrote: > > 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]); > > We can now make it const. Done. > > - *(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 7d34592471db..15149d34e43b 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 > > @@ -189,3 +190,69 @@ static void __maybe_unused clear_cap(struct __test_metadata *const _metadata, > > { > > _effective_cap(_metadata, caps, CAP_CLEAR); > > } > > + > > +/* Receives an FD from a UNIX socket. Returns the received FD, -1 on error. */ > > +static int __maybe_unused 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; > > It could be useful to return -errno for recv_fd() and send_fd(), and update > the description accordingly. That would enable to quickly know the error > with the ASSERT_*() calls. Done, good idea. > > + cmsg = CMSG_FIRSTHDR(&msg); > > + if (cmsg->cmsg_len != CMSG_LEN(sizeof(fd_rx))) > > + return -1; I made it return -EIO in the case where the other side sends invalid data. > > + 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. */ > > +static int __maybe_unused 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 > > "Enables"… Done. > > + * 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. */ > > This comment is not necessary. Done. > > + 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); > > You might want to add a "return" here to help the compiler (and the reader). Done. > > + } > > + > > + 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 */ --