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 X-Spam-Level: X-Spam-Status: No, score=-11.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNWANTED_LANGUAGE_BODY,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A935C0044D for ; Mon, 16 Mar 2020 22:45:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 09DB620679 for ; Mon, 16 Mar 2020 22:45:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vt9xGjrz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732858AbgCPWpW (ORCPT ); Mon, 16 Mar 2020 18:45:22 -0400 Received: from mail-qk1-f193.google.com ([209.85.222.193]:46125 "EHLO mail-qk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732739AbgCPWpW (ORCPT ); Mon, 16 Mar 2020 18:45:22 -0400 Received: by mail-qk1-f193.google.com with SMTP id f28so29280280qkk.13 for ; Mon, 16 Mar 2020 15:45:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=hgJDmNWpEQbJNc4mEAcOWwsH7T6CJyPxmEKaqzHkWRI=; b=vt9xGjrzy1sllJMWQyLR9YN6PSvzCc45anF78sNauPPwQ80lenVoIb8FJFwav/nU6k tqbTYI2fPtG8BjltvYblpOYEPnnU4JgNcxGXN7VoVQ00Gkvp0uYskz4OyzhsBSgrbrOs lYq/3u6Oxhl7oWt4xtLpqlFDSGBdmLA50INziLyVxC68CYIErlHO+Vt5ySlt2FGpMk7u KuesN4LLsLC7ZU5Hf5uu4Lre0Sxl4jTq2bPMo62U3/cgeRwmd97XU2dMzUbRQCoTQgpZ VzeEbIlfoJHL2VkRsyz+QInt/xFZiE/z5i8I3CKYSXiOtGUZ2MqQ0tt4k5xETol5dlyg tIog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=hgJDmNWpEQbJNc4mEAcOWwsH7T6CJyPxmEKaqzHkWRI=; b=skb+OayQPlDpptpCNG6sIvLJgcgBepD1MnvjF8LXghYNpehCgsPf/ENMU0FXtj3e/K qPjmwOsY6+EXE03Z1Ojd0XtleApxEo1A8L4clctBBL/py3B1V8rj+hPz5DHvdsuihDca cS5hVZ5r4U8YYn/50C1mY06gR+sS1TSbdHgkTaPlpnElvvihWKtBN+m84IfP6JDIuWZQ 7jt67bj8wfOO4SSuzrkrbUyTcsZPd4BxQR+HyC7SA1TkxJV/utXdQr2mCt/qH/922Y0K D5ZQqeOBGSkLmn+4TPu47VakXVFDDN4DUKfpRFzohFlZ+RwCbgh74tA2WYdT0aVwCF7M Kw0w== X-Gm-Message-State: ANhLgQ1mcGLcx6AZeCKCVG5q56hst6ZUkBibqLeDwS+p2HsdH1j+RW7v 0zs3GfUp3emzIpWNveG601inGHXzqzOpUowyooQd7Q== X-Google-Smtp-Source: ADFU+vsWuZfS9776j83LnbndqR5TE3XPh9nfhfkXEuMsxVFxFoVnY3pJnwaVZEFFVknptVWgaxNboLiWPv09KHkUElo= X-Received: by 2002:a37:7a04:: with SMTP id v4mr2074695qkc.340.1584398720257; Mon, 16 Mar 2020 15:45:20 -0700 (PDT) MIME-Version: 1.0 References: <20200312131531.3615556-1-christian.brauner@ubuntu.com> <20200313152420.138777-1-christian.brauner@ubuntu.com> <20200313152420.138777-3-christian.brauner@ubuntu.com> <202003131608.DA96ECE4D@keescook> In-Reply-To: <202003131608.DA96ECE4D@keescook> From: Hridya Valsaraju Date: Mon, 16 Mar 2020 15:44:44 -0700 Message-ID: Subject: Re: [PATCH v2 3/3] binderfs: add stress test for binderfs binder devices To: Kees Cook Cc: Christian Brauner , Greg Kroah-Hartman , Todd Kjos , LKML , ard.biesheuvel@linaro.org, ardb@kernel.org, =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= , Joel Fernandes , John Stultz , Android Kernel Team , linux-kselftest@vger.kernel.org, Martijn Coenen , naresh.kamboju@linaro.org, shuah@kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 13, 2020 at 4:08 PM Kees Cook wrote: > > On Fri, Mar 13, 2020 at 04:24:20PM +0100, Christian Brauner wrote: > > This adds a stress test that should hopefully help us catch regressions > > for [1], [2], and [3]. > > > > [1]: 2669b8b0c798 ("binder: prevent UAF for binderfs devices") > > [2]: f0fe2c0f050d ("binder: prevent UAF for binderfs devices II") > > [3]: 211b64e4b5b6 ("binderfs: use refcount for binder control devices too") > > Cc: Kees Cook : > > Signed-off-by: Christian Brauner > > Reviewed-by: Kees Cook > > -Kees > Thank you for creating these tests Christian! I was able to get them running on the cuttlefish platform with the ACK android-mainline branch. Regards, Hridya > > --- > > /* v2 */ > > - Kees Cook : > > - Switch to unique mountpoint through mkdtemp(). > > --- > > .../selftests/filesystems/binderfs/Makefile | 2 +- > > .../filesystems/binderfs/binderfs_test.c | 426 ++++++++++++++---- > > 2 files changed, 334 insertions(+), 94 deletions(-) > > > > diff --git a/tools/testing/selftests/filesystems/binderfs/Makefile b/tools/testing/selftests/filesystems/binderfs/Makefile > > index 75315d9ba7a9..8af25ae96049 100644 > > --- a/tools/testing/selftests/filesystems/binderfs/Makefile > > +++ b/tools/testing/selftests/filesystems/binderfs/Makefile > > @@ -1,6 +1,6 @@ > > # SPDX-License-Identifier: GPL-2.0 > > > > -CFLAGS += -I../../../../../usr/include/ > > +CFLAGS += -I../../../../../usr/include/ -pthread > > TEST_GEN_PROGS := binderfs_test > > > > binderfs_test: binderfs_test.c ../../kselftest.h ../../kselftest_harness.h > > diff --git a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c > > index 818eb49f8125..8a6b507e34a8 100644 > > --- a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c > > +++ b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c > > @@ -3,15 +3,20 @@ > > #define _GNU_SOURCE > > #include > > #include > > +#include > > #include > > #include > > #include > > #include > > #include > > +#include > > #include > > #include > > +#include > > #include > > +#include > > #include > > +#include > > #include > > #include > > #include > > @@ -19,100 +24,26 @@ > > #include "../../kselftest.h" > > #include "../../kselftest_harness.h" > > > > -static ssize_t write_nointr(int fd, const void *buf, size_t count) > > -{ > > - ssize_t ret; > > -again: > > - ret = write(fd, buf, count); > > - if (ret < 0 && errno == EINTR) > > - goto again; > > - > > - return ret; > > -} > > - > > -static void write_to_file(const char *filename, const void *buf, size_t count, > > - int allowed_errno) > > -{ > > - int fd, saved_errno; > > - ssize_t ret; > > - > > - fd = open(filename, O_WRONLY | O_CLOEXEC); > > - if (fd < 0) > > - ksft_exit_fail_msg("%s - Failed to open file %s\n", > > - strerror(errno), filename); > > +#define DEFAULT_THREADS 4 > > > > - ret = write_nointr(fd, buf, count); > > - if (ret < 0) { > > - if (allowed_errno && (errno == allowed_errno)) { > > - close(fd); > > - return; > > - } > > +#define PTR_TO_INT(p) ((int)((intptr_t)(p))) > > +#define INT_TO_PTR(u) ((void *)((intptr_t)(u))) > > > > - goto on_error; > > +#define close_prot_errno_disarm(fd) \ > > + if (fd >= 0) { \ > > + int _e_ = errno; \ > > + close(fd); \ > > + errno = _e_; \ > > + fd = -EBADF; \ > > } > > > > - if ((size_t)ret != count) > > - goto on_error; > > - > > - close(fd); > > - return; > > - > > -on_error: > > - saved_errno = errno; > > - close(fd); > > - errno = saved_errno; > > - > > - if (ret < 0) > > - ksft_exit_fail_msg("%s - Failed to write to file %s\n", > > - strerror(errno), filename); > > - > > - ksft_exit_fail_msg("Failed to write to file %s\n", filename); > > -} > > - > > -static void change_to_userns(void) > > -{ > > - int ret; > > - uid_t uid; > > - gid_t gid; > > - /* {g,u}id_map files only allow a max of 4096 bytes written to them */ > > - char idmap[4096]; > > - > > - uid = getuid(); > > - gid = getgid(); > > - > > - ret = unshare(CLONE_NEWUSER); > > - if (ret < 0) > > - ksft_exit_fail_msg("%s - Failed to unshare user namespace\n", > > - strerror(errno)); > > - > > - write_to_file("/proc/self/setgroups", "deny", strlen("deny"), ENOENT); > > - > > - ret = snprintf(idmap, sizeof(idmap), "0 %d 1", uid); > > - if (ret < 0 || (size_t)ret >= sizeof(idmap)) > > - ksft_exit_fail_msg("%s - Failed to prepare uid mapping\n", > > - strerror(errno)); > > - > > - write_to_file("/proc/self/uid_map", idmap, strlen(idmap), 0); > > - > > - ret = snprintf(idmap, sizeof(idmap), "0 %d 1", gid); > > - if (ret < 0 || (size_t)ret >= sizeof(idmap)) > > - ksft_exit_fail_msg("%s - Failed to prepare uid mapping\n", > > - strerror(errno)); > > - > > - write_to_file("/proc/self/gid_map", idmap, strlen(idmap), 0); > > - > > - ret = setgid(0); > > - if (ret) > > - ksft_exit_fail_msg("%s - Failed to setgid(0)\n", > > - strerror(errno)); > > +#define log_exit(format, ...) \ > > + ({ \ > > + fprintf(stderr, format "\n", ##__VA_ARGS__); \ > > + exit(EXIT_FAILURE); \ > > + }) > > > > - ret = setuid(0); > > - if (ret) > > - ksft_exit_fail_msg("%s - Failed to setgid(0)\n", > > - strerror(errno)); > > -} > > - > > -static void change_to_mountns(void) > > +static void change_mountns(void) > > { > > int ret; > > > > @@ -144,7 +75,7 @@ static int __do_binderfs_test(void) > > char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX", > > device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME]; > > > > - change_to_mountns(); > > + change_mountns(); > > > > if (!mkdtemp(binderfs_mntpt)) > > ksft_exit_fail_msg( > > @@ -253,6 +184,288 @@ static int __do_binderfs_test(void) > > return 0; > > } > > > > +static int wait_for_pid(pid_t pid) > > +{ > > + int status, ret; > > + > > +again: > > + ret = waitpid(pid, &status, 0); > > + if (ret == -1) { > > + if (errno == EINTR) > > + goto again; > > + > > + return -1; > > + } > > + > > + if (!WIFEXITED(status)) > > + return -1; > > + > > + return WEXITSTATUS(status); > > +} > > + > > +static int setid_userns_root(void) > > +{ > > + if (setuid(0)) > > + return -1; > > + if (setgid(0)) > > + return -1; > > + > > + setfsuid(0); > > + setfsgid(0); > > + > > + return 0; > > +} > > + > > +enum idmap_type { > > + UID_MAP, > > + GID_MAP, > > +}; > > + > > +static ssize_t read_nointr(int fd, void *buf, size_t count) > > +{ > > + ssize_t ret; > > +again: > > + ret = read(fd, buf, count); > > + if (ret < 0 && errno == EINTR) > > + goto again; > > + > > + return ret; > > +} > > + > > +static ssize_t write_nointr(int fd, const void *buf, size_t count) > > +{ > > + ssize_t ret; > > +again: > > + ret = write(fd, buf, count); > > + if (ret < 0 && errno == EINTR) > > + goto again; > > + > > + return ret; > > +} > > + > > +static int write_id_mapping(enum idmap_type type, pid_t pid, const char *buf, > > + size_t buf_size) > > +{ > > + int fd; > > + int ret; > > + char path[4096]; > > + > > + if (type == GID_MAP) { > > + int setgroups_fd; > > + > > + snprintf(path, sizeof(path), "/proc/%d/setgroups", pid); > > + setgroups_fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW); > > + if (setgroups_fd < 0 && errno != ENOENT) > > + return -1; > > + > > + if (setgroups_fd >= 0) { > > + ret = write_nointr(setgroups_fd, "deny", sizeof("deny") - 1); > > + close_prot_errno_disarm(setgroups_fd); > > + if (ret != sizeof("deny") - 1) > > + return -1; > > + } > > + } > > + > > + switch (type) { > > + case UID_MAP: > > + ret = snprintf(path, sizeof(path), "/proc/%d/uid_map", pid); > > + break; > > + case GID_MAP: > > + ret = snprintf(path, sizeof(path), "/proc/%d/gid_map", pid); > > + break; > > + default: > > + return -1; > > + } > > + if (ret < 0 || ret >= sizeof(path)) > > + return -E2BIG; > > + > > + fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW); > > + if (fd < 0) > > + return -1; > > + > > + ret = write_nointr(fd, buf, buf_size); > > + close_prot_errno_disarm(fd); > > + if (ret != buf_size) > > + return -1; > > + > > + return 0; > > +} > > + > > +static void change_userns(int syncfds[2]) > > +{ > > + int ret; > > + char buf; > > + > > + close_prot_errno_disarm(syncfds[1]); > > + > > + ret = unshare(CLONE_NEWUSER); > > + if (ret < 0) > > + ksft_exit_fail_msg("%s - Failed to unshare user namespace\n", > > + strerror(errno)); > > + > > + ret = write_nointr(syncfds[0], "1", 1); > > + if (ret != 1) > > + ksft_exit_fail_msg("write_nointr() failed\n"); > > + > > + ret = read_nointr(syncfds[0], &buf, 1); > > + if (ret != 1) > > + ksft_exit_fail_msg("read_nointr() failed\n"); > > + > > + close_prot_errno_disarm(syncfds[0]); > > + > > + if (setid_userns_root()) > > + ksft_exit_fail_msg("setid_userns_root() failed"); > > +} > > + > > +static void change_idmaps(int syncfds[2], pid_t pid) > > +{ > > + int ret; > > + char buf; > > + char id_map[4096]; > > + > > + close_prot_errno_disarm(syncfds[0]); > > + > > + ret = read_nointr(syncfds[1], &buf, 1); > > + if (ret != 1) > > + ksft_exit_fail_msg("read_nointr() failed\n"); > > + > > + snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid()); > > + ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map)); > > + if (ret) > > + ksft_exit_fail_msg("write_id_mapping(UID_MAP) failed"); > > + > > + snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid()); > > + ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map)); > > + if (ret) > > + ksft_exit_fail_msg("write_id_mapping(GID_MAP) failed"); > > + > > + ret = write_nointr(syncfds[1], "1", 1); > > + if (ret != 1) > > + ksft_exit_fail_msg("write_nointr() failed"); > > + > > + close_prot_errno_disarm(syncfds[1]); > > +} > > + > > +static void *binder_version_thread(void *data) > > +{ > > + int fd = PTR_TO_INT(data); > > + struct binder_version version = { 0 }; > > + int ret; > > + > > + ret = ioctl(fd, BINDER_VERSION, &version); > > + if (ret < 0) > > + ksft_print_msg("%s - Failed to open perform BINDER_VERSION request\n", strerror(errno)); > > + > > + pthread_exit(data); > > +} > > + > > +/* > > + * Regression test: > > + * 2669b8b0c798 ("binder: prevent UAF for binderfs devices") > > + * f0fe2c0f050d ("binder: prevent UAF for binderfs devices II") > > + * 211b64e4b5b6 ("binderfs: use refcount for binder control devices too") > > + */ > > +TEST(binderfs_stress) > > +{ > > + int fds[1000]; > > + int syncfds[2]; > > + pid_t pid; > > + int fd, ret; > > + size_t len; > > + struct binderfs_device device = { 0 }; > > + char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX", > > + device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME]; > > + > > + ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds); > > + if (ret < 0) > > + ksft_exit_fail_msg("%s - Failed to create socket pair", strerror(errno)); > > + > > + pid = fork(); > > + if (pid < 0) { > > + close_prot_errno_disarm(syncfds[0]); > > + close_prot_errno_disarm(syncfds[1]); > > + ksft_exit_fail_msg("%s - Failed to fork", strerror(errno)); > > + } > > + > > + if (pid == 0) { > > + int i, j, k, nthreads; > > + pthread_attr_t attr; > > + pthread_t threads[DEFAULT_THREADS]; > > + change_userns(syncfds); > > + change_mountns(); > > + > > + if (!mkdtemp(binderfs_mntpt)) > > + log_exit("%s - Failed to create binderfs mountpoint\n", > > + strerror(errno)); > > + > > + ret = mount(NULL, binderfs_mntpt, "binder", 0, 0); > > + if (ret < 0) > > + log_exit("%s - Failed to mount binderfs\n", strerror(errno)); > > + > > + for (int i = 0; i < ARRAY_SIZE(fds); i++) { > > + > > + snprintf(device_path, sizeof(device_path), > > + "%s/binder-control", binderfs_mntpt); > > + fd = open(device_path, O_RDONLY | O_CLOEXEC); > > + if (fd < 0) > > + log_exit("%s - Failed to open binder-control device\n", strerror(errno)); > > + > > + memset(&device, 0, sizeof(device)); > > + snprintf(device.name, sizeof(device.name), "%d", i); > > + ret = ioctl(fd, BINDER_CTL_ADD, &device); > > + close_prot_errno_disarm(fd); > > + if (ret < 0) > > + log_exit("%s - Failed to allocate new binder device\n", strerror(errno)); > > + > > + snprintf(device_path, sizeof(device_path), "%s/%d", > > + binderfs_mntpt, i); > > + fds[i] = open(device_path, O_RDONLY | O_CLOEXEC); > > + if (fds[i] < 0) > > + log_exit("%s - Failed to open binder device\n", strerror(errno)); > > + } > > + > > + ret = umount2(binderfs_mntpt, MNT_DETACH); > > + rmdir_protect_errno(binderfs_mntpt); > > + if (ret < 0) > > + log_exit("%s - Failed to unmount binderfs\n", strerror(errno)); > > + > > + nthreads = get_nprocs_conf(); > > + if (nthreads > DEFAULT_THREADS) > > + nthreads = DEFAULT_THREADS; > > + > > + pthread_attr_init(&attr); > > + for (k = 0; k < ARRAY_SIZE(fds); k++) { > > + for (i = 0; i < nthreads; i++) { > > + ret = pthread_create(&threads[i], &attr, binder_version_thread, INT_TO_PTR(fds[k])); > > + if (ret) { > > + ksft_print_msg("%s - Failed to create thread %d\n", strerror(errno), i); > > + break; > > + } > > + } > > + > > + for (j = 0; j < i; j++) { > > + void *fdptr = NULL; > > + > > + ret = pthread_join(threads[j], &fdptr); > > + if (ret) > > + ksft_print_msg("%s - Failed to join thread %d for fd %d\n", strerror(errno), j, PTR_TO_INT(fdptr)); > > + } > > + } > > + pthread_attr_destroy(&attr); > > + > > + for (k = 0; k < ARRAY_SIZE(fds); k++) > > + close(fds[k]); > > + > > + exit(EXIT_SUCCESS); > > + } > > + > > + change_idmaps(syncfds, pid); > > + > > + ret = wait_for_pid(pid); > > + if (ret) > > + ksft_exit_fail_msg("wait_for_pid() failed"); > > +} > > + > > TEST(binderfs_test_privileged) > > { > > if (geteuid() != 0) > > @@ -264,10 +477,37 @@ TEST(binderfs_test_privileged) > > > > TEST(binderfs_test_unprivileged) > > { > > - change_to_userns(); > > + int ret; > > + int syncfds[2]; > > + pid_t pid; > > > > - if (__do_binderfs_test() == 1) > > - XFAIL(return, "The Android binderfs filesystem is not available"); > > + ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds); > > + if (ret < 0) > > + ksft_exit_fail_msg("%s - Failed to create socket pair", strerror(errno)); > > + > > + pid = fork(); > > + if (pid < 0) { > > + close_prot_errno_disarm(syncfds[0]); > > + close_prot_errno_disarm(syncfds[1]); > > + ksft_exit_fail_msg("%s - Failed to fork", strerror(errno)); > > + } > > + > > + if (pid == 0) { > > + change_userns(syncfds); > > + if (__do_binderfs_test() == 1) > > + exit(2); > > + exit(EXIT_SUCCESS); > > + } > > + > > + change_idmaps(syncfds, pid); > > + > > + ret = wait_for_pid(pid); > > + if (ret) { > > + if (ret == 2) > > + XFAIL(return, "The Android binderfs filesystem is not available"); > > + else > > + ksft_exit_fail_msg("wait_for_pid() failed"); > > + } > > } > > > > TEST_HARNESS_MAIN > > -- > > 2.25.1 > > > > -- > Kees Cook