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/* * Copyright (c) 2021 Alexey Dobriyan <adobriyan@gmail.com> * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *//* * Test that "mount -t proc -o subset=pid" hides everything but pids, * /proc/self and /proc/thread-self. */#undef NDEBUG#include <assert.h>#include <errno.h>#include <sched.h>#include <stdbool.h>#include <stdlib.h>#include <string.h>#include <sys/mount.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <dirent.h>#include <unistd.h>#include <stdio.h> static inline bool streq(const char *a, const char *b){	return strcmp(a, b) == 0;} static void make_private_proc(void){	if (unshare(CLONE_NEWNS) == -1) {		if (errno == ENOSYS || errno == EPERM) {			exit(4);		}		exit(1);	}	if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {		exit(1);	}	if (mount(NULL, "/proc", "proc", 0, "subset=pid") == -1) {		exit(1);	}} static bool string_is_pid(const char *s){	while (1) {		switch (*s++) {		case '0':case '1':case '2':case '3':case '4':		case '5':case '6':case '7':case '8':case '9':			continue; 		case '\0':			return true; 		default:			return false;		}	}} int main(void){	make_private_proc(); 	DIR *d = opendir("/proc");	assert(d); 	struct dirent *de; 	bool dot = false;	bool dot_dot = false;	bool self = false;	bool thread_self = false; 	while ((de = readdir(d))) {		if (streq(de->d_name, ".")) {			assert(!dot);			dot = true;			assert(de->d_type == DT_DIR);		} else if (streq(de->d_name, "..")) {			assert(!dot_dot);			dot_dot = true;			assert(de->d_type == DT_DIR);		} else if (streq(de->d_name, "self")) {			assert(!self);			self = true;			assert(de->d_type == DT_LNK);		} else if (streq(de->d_name, "thread-self")) {			assert(!thread_self);			thread_self = true;			assert(de->d_type == DT_LNK);		} else {			if (!string_is_pid(de->d_name)) {				fprintf(stderr, "d_name '%s'\n", de->d_name);				assert(0);			}			assert(de->d_type == DT_DIR);		}	} 	char c;	int rv = readlink("/proc/cpuinfo", &c, 1);	assert(rv == -1 && errno == ENOENT); 	int fd = open("/proc/cpuinfo", O_RDONLY);	assert(fd == -1 && errno == ENOENT); 	return 0;}