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1/*2 * Copyright (c) 2021 Alexey Dobriyan <adobriyan@gmail.com>3 *4 * Permission to use, copy, modify, and distribute this software for any5 * purpose with or without fee is hereby granted, provided that the above6 * copyright notice and this permission notice appear in all copies.7 *8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.15 */16/*17 * Test that "mount -t proc -o subset=pid" hides everything but pids,18 * /proc/self and /proc/thread-self.19 */20#undef NDEBUG21#include <assert.h>22#include <errno.h>23#include <sched.h>24#include <stdbool.h>25#include <stdlib.h>26#include <string.h>27#include <sys/mount.h>28#include <sys/types.h>29#include <sys/stat.h>30#include <fcntl.h>31#include <dirent.h>32#include <unistd.h>33#include <stdio.h>34 35static inline bool streq(const char *a, const char *b)36{37 return strcmp(a, b) == 0;38}39 40static void make_private_proc(void)41{42 if (unshare(CLONE_NEWNS) == -1) {43 if (errno == ENOSYS || errno == EPERM) {44 exit(4);45 }46 exit(1);47 }48 if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {49 exit(1);50 }51 if (mount(NULL, "/proc", "proc", 0, "subset=pid") == -1) {52 exit(1);53 }54}55 56static bool string_is_pid(const char *s)57{58 while (1) {59 switch (*s++) {60 case '0':case '1':case '2':case '3':case '4':61 case '5':case '6':case '7':case '8':case '9':62 continue;63 64 case '\0':65 return true;66 67 default:68 return false;69 }70 }71}72 73int main(void)74{75 make_private_proc();76 77 DIR *d = opendir("/proc");78 assert(d);79 80 struct dirent *de;81 82 bool dot = false;83 bool dot_dot = false;84 bool self = false;85 bool thread_self = false;86 87 while ((de = readdir(d))) {88 if (streq(de->d_name, ".")) {89 assert(!dot);90 dot = true;91 assert(de->d_type == DT_DIR);92 } else if (streq(de->d_name, "..")) {93 assert(!dot_dot);94 dot_dot = true;95 assert(de->d_type == DT_DIR);96 } else if (streq(de->d_name, "self")) {97 assert(!self);98 self = true;99 assert(de->d_type == DT_LNK);100 } else if (streq(de->d_name, "thread-self")) {101 assert(!thread_self);102 thread_self = true;103 assert(de->d_type == DT_LNK);104 } else {105 if (!string_is_pid(de->d_name)) {106 fprintf(stderr, "d_name '%s'\n", de->d_name);107 assert(0);108 }109 assert(de->d_type == DT_DIR);110 }111 }112 113 char c;114 int rv = readlink("/proc/cpuinfo", &c, 1);115 assert(rv == -1 && errno == ENOENT);116 117 int fd = open("/proc/cpuinfo", O_RDONLY);118 assert(fd == -1 && errno == ENOENT);119 120 return 0;121}122