[v10,1/6] generic/631: add test for detached mount propagation

Message ID	20210322134522.916512-2-brauner@kernel.org (mailing list archive)
State	New, archived
Headers	show Return-Path: <fstests-owner@kernel.org> From: Christian Brauner <brauner@kernel.org> To: Eryu Guan <guan@eryu.me>, fstests@vger.kernel.org, Christoph Hellwig <hch@lst.de> Cc: "Darrick J . Wong" <djwong@kernel.org>, David Howells <dhowells@redhat.com>, Christian Brauner <christian.brauner@ubuntu.com> Subject: [PATCH v10 1/6] generic/631: add test for detached mount propagation Date: Mon, 22 Mar 2021 14:45:17 +0100 Message-Id: <20210322134522.916512-2-brauner@kernel.org> In-Reply-To: <20210322134522.916512-1-brauner@kernel.org> References: <20210322134522.916512-1-brauner@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	fstests: add idmapped mounts tests \| expand [v10,0/6] fstests: add idmapped mounts tests [v10,1/6] generic/631: add test for detached mount propagation [v10,3/6] common/rc: add _scratch_{u}mount_idmapped() helpers [v10,4/6] common/quota: move _qsetup() helper to common code [v10,5/6] xfs/529: quotas and idmapped mounts [v10,6/6] xfs/530: quotas on idmapped mounts

diff --git a/.gitignore b/.gitignore index f3bc0a4f..72bd40a0 100644 --- a/.gitignore +++ b/.gitignore @@ -62,6 +62,7 @@ /src/cloner /src/dbtest /src/deduperace +/src/detached_mounts_propagation /src/devzero /src/dio-interleaved /src/dio-invalidate-cache diff --git a/src/Makefile b/src/Makefile index 3d729a34..99019e6e 100644 --- a/src/Makefile +++ b/src/Makefile @@ -29,7 +29,8 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ attr-list-by-handle-cursor-test listxattr dio-interleaved t_dir_type \ dio-invalidate-cache stat_test t_encrypted_d_revalidate \ attr_replace_test swapon mkswap t_attr_corruption t_open_tmpfiles \ - fscrypt-crypt-util bulkstat_null_ocount splice-test chprojid_fail + fscrypt-crypt-util bulkstat_null_ocount splice-test chprojid_fail \ + detached_mounts_propagation SUBDIRS = log-writes perf diff --git a/src/detached_mounts_propagation.c b/src/detached_mounts_propagation.c new file mode 100644 index 00000000..4a588e46 --- /dev/null +++ b/src/detached_mounts_propagation.c @@ -0,0 +1,252 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ +/* + * Copyright (c) 2021 Christian Brauner <christian.brauner@ubuntu.com> + * All Rights Reserved. + * + * Regression test to verify that creating a series of detached mounts, + * attaching them to the filesystem, and unmounting them does not trigger an + * integer overflow in ns->mounts causing the kernel to block any new mounts in + * count_mounts() and returning ENOSPC because it falsely assumes that the + * maximum number of mounts in the mount namespace has been reached, i.e. it + * thinks it can't fit the new mounts into the mount namespace anymore. + */ + +#include <errno.h> +#include <fcntl.h> +#include <getopt.h> +#include <limits.h> +#include <sched.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/mount.h> +#include <sys/stat.h> +#include <sys/syscall.h> +#include <sys/types.h> +#include <unistd.h> + +/* open_tree() */ +#ifndef OPEN_TREE_CLONE +#define OPEN_TREE_CLONE 1 +#endif + +#ifndef OPEN_TREE_CLOEXEC +#define OPEN_TREE_CLOEXEC O_CLOEXEC +#endif + +#ifndef __NR_open_tree + #if defined __alpha__ + #define __NR_open_tree 538 + #elif defined _MIPS_SIM + #if _MIPS_SIM == _MIPS_SIM_ABI32 /* o32 */ + #define __NR_open_tree 4428 + #endif + #if _MIPS_SIM == _MIPS_SIM_NABI32 /* n32 */ + #define __NR_open_tree 6428 + #endif + #if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */ + #define __NR_open_tree 5428 + #endif + #elif defined __ia64__ + #define __NR_open_tree (428 + 1024) + #else + #define __NR_open_tree 428 + #endif +#endif + +/* move_mount() */ +#ifndef MOVE_MOUNT_F_EMPTY_PATH +#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004 /* Empty from path permitted */ +#endif + +#ifndef __NR_move_mount + #if defined __alpha__ + #define __NR_move_mount 539 + #elif defined _MIPS_SIM + #if _MIPS_SIM == _MIPS_SIM_ABI32 /* o32 */ + #define __NR_move_mount 4429 + #endif + #if _MIPS_SIM == _MIPS_SIM_NABI32 /* n32 */ + #define __NR_move_mount 6429 + #endif + #if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */ + #define __NR_move_mount 5429 + #endif + #elif defined __ia64__ + #define __NR_move_mount (428 + 1024) + #else + #define __NR_move_mount 429 + #endif +#endif + +static inline int sys_open_tree(int dfd, const char *filename, unsigned int flags) +{ + return syscall(__NR_open_tree, dfd, filename, flags); +} + +static inline int sys_move_mount(int from_dfd, const char *from_pathname, int to_dfd, + const char *to_pathname, unsigned int flags) +{ + return syscall(__NR_move_mount, from_dfd, from_pathname, to_dfd, to_pathname, flags); +} + +static bool is_shared_mountpoint(const char *path) +{ + bool shared = false; + FILE *f = NULL; + char *line = NULL; + int i; + size_t len = 0; + + f = fopen("/proc/self/mountinfo", "re"); + if (!f) + return 0; + + while (getline(&line, &len, f) > 0) { + char *slider1, *slider2; + + for (slider1 = line, i = 0; slider1 && i < 4; i++) + slider1 = strchr(slider1 + 1, ' '); + + if (!slider1) + continue; + + slider2 = strchr(slider1 + 1, ' '); + if (!slider2) + continue; + + *slider2 = '\0'; + if (strcmp(slider1 + 1, path) == 0) { + /* This is the path. Is it shared? */ + slider1 = strchr(slider2 + 1, ' '); + if (slider1 && strstr(slider1, "shared:")) { + shared = true; + break; + } + } + } + fclose(f); + free(line); + + return shared; +} + +static void usage(void) +{ + const char *text = "mount-new [--recursive] <base-dir>\n"; + fprintf(stderr, "%s", text); + _exit(EXIT_SUCCESS); +} + +#define exit_usage(format, ...) \ + ({ \ + fprintf(stderr, format "\n", ##__VA_ARGS__); \ + usage(); \ + }) + +#define exit_log(format, ...) \ + ({ \ + fprintf(stderr, format "\n", ##__VA_ARGS__); \ + exit(EXIT_FAILURE); \ + }) + +static const struct option longopts[] = { + {"help", no_argument, 0, 'a'}, + { NULL, no_argument, 0, 0 }, +}; + +int main(int argc, char *argv[]) +{ + int exit_code = EXIT_SUCCESS, index = 0; + int dfd, fd_tree, new_argc, ret; + char *base_dir; + char *const *new_argv; + char target[PATH_MAX]; + + while ((ret = getopt_long_only(argc, argv, "", longopts, &index)) != -1) { + switch (ret) { + case 'a': + /* fallthrough */ + default: + usage(); + } + } + + new_argv = &argv[optind]; + new_argc = argc - optind; + if (new_argc < 1) + exit_usage("Missing base directory\n"); + base_dir = new_argv[0]; + + if (*base_dir != '/') + exit_log("Please specify an absolute path"); + + /* Ensure that target is a shared mountpoint. */ + if (!is_shared_mountpoint(base_dir)) + exit_log("Please ensure that \"%s\" is a shared mountpoint", base_dir); + + ret = unshare(CLONE_NEWNS); + if (ret < 0) + exit_log("%m - Failed to create new mount namespace"); + + ret = mount(NULL, base_dir, NULL, MS_REC | MS_SHARED, NULL); + if (ret < 0) + exit_log("%m - Failed to make base_dir shared mountpoint"); + + dfd = open(base_dir, O_RDONLY | O_DIRECTORY | O_CLOEXEC); + if (dfd < 0) + exit_log("%m - Failed to open base directory \"%s\"", base_dir); + + ret = mkdirat(dfd, "detached-move-mount", 0755); + if (ret < 0) + exit_log("%m - Failed to create required temporary directories"); + + ret = snprintf(target, sizeof(target), "%s/detached-move-mount", base_dir); + if (ret < 0 || (size_t)ret >= sizeof(target)) + exit_log("%m - Failed to assemble target path"); + + /* + * Having a mount table with 10000 mounts is already quite excessive + * and shoult account even for weird test systems. + */ + for (size_t i = 0; i < 10000; i++) { + fd_tree = sys_open_tree(dfd, "detached-move-mount", + OPEN_TREE_CLONE | + OPEN_TREE_CLOEXEC | + AT_EMPTY_PATH); + if (fd_tree < 0) { + if (errno == ENOSYS) /* New mount API not (fully) supported. */ + break; + + fprintf(stderr, "%m - Failed to open %d(detached-move-mount)", dfd); + exit_code = EXIT_FAILURE; + break; + } + + ret = sys_move_mount(fd_tree, "", dfd, "detached-move-mount", MOVE_MOUNT_F_EMPTY_PATH); + if (ret < 0) { + if (errno == ENOSPC) + fprintf(stderr, "%m - Buggy mount counting"); + else if (errno == ENOSYS) /* New mount API not (fully) supported. */ + break; + else + fprintf(stderr, "%m - Failed to attach mount to %d(detached-move-mount)", dfd); + exit_code = EXIT_FAILURE; + break; + } + close(fd_tree); + + ret = umount2(target, MNT_DETACH); + if (ret < 0) { + fprintf(stderr, "%m - Failed to unmount %s", target); + exit_code = EXIT_FAILURE; + break; + } + } + + (void)unlinkat(dfd, "detached-move-mount", AT_REMOVEDIR); + close(dfd); + + exit(exit_code); +} diff --git a/tests/generic/631 b/tests/generic/631 new file mode 100644 index 00000000..0b6cac42 --- /dev/null +++ b/tests/generic/631 @@ -0,0 +1,43 @@ +#! /bin/bash +# SPDX-License-Identifier: GPL-2.0+ +# +# Copyright (c) 2021 Christian Brauner <christian.brauner@ubuntu.com> +# All Rights Reserved. +# +# FS QA Test No. 631 +# +# Regression test to verify that creating a series of detached mounts, +# attaching them to the filesystem, and unmounting them does not trigger an +# integer overflow in ns->mounts causing the kernel to block any new mounts in +# count_mounts() and returning ENOSPC because it falsely assumes that the +# maximum number of mounts in the mount namespace has been reached, i.e. it +# thinks it can't fit the new mounts into the mount namespace anymore. +# +seq=`basename $0` +seqres=$RESULT_DIR/$seq +echo "QA output created by $seq" + +here=`pwd` +tmp=/tmp/$$ +status=1 # failure is the default! +trap "_cleanup; exit \$status" 0 1 2 3 15 + +_cleanup() +{ + cd / + rm -f $tmp.* +} + +. ./common/rc + +rm -f $seqres.full + +_supported_fs generic +_require_test +_require_test_program "detached_mounts_propagation" + +$here/src/detached_mounts_propagation $TEST_DIR >> $seqres.full +status=$? + +echo silence is golden +exit diff --git a/tests/generic/631.out b/tests/generic/631.out new file mode 100644 index 00000000..ce88f447 --- /dev/null +++ b/tests/generic/631.out @@ -0,0 +1,2 @@ +QA output created by 631 +silence is golden diff --git a/tests/generic/group b/tests/generic/group index 7c7531d1..151f8af2 100644 --- a/tests/generic/group +++ b/tests/generic/group @@ -633,3 +633,4 @@ 628 auto quick rw clone 629 auto quick rw copy_range 630 auto quick rw dedupe clone +631 auto quick mount

[v10,1/6] generic/631: add test for detached mount propagation

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