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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;
}
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