Commit 268af17a authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Linus Torvalds
Browse files

selftests: proc: test subset=pid 

Test that /proc instance mounted with

	mount -t proc -o subset=pid

contains only ".", "..", "self", "thread-self" and pid directories.

Note:
Currently "subset=pid" doesn't return "." and ".." via readdir.
This must be a bug.

Link: https://lkml.kernel.org/r/YFYZZ7WGaZlsnChS@localhost.localdomain


Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Acked-by: default avatarAlexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1dcdd7ef

tools/testing/selftests/proc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ TEST_GEN_PROGS += proc-self-map-files-001 
TEST_GEN_PROGS += proc-self-map-files-002

TEST_GEN_PROGS += proc-self-syscall

TEST_GEN_PROGS += proc-self-wchan

TEST_GEN_PROGS += proc-subset-pid

TEST_GEN_PROGS += proc-uptime-001

TEST_GEN_PROGS += proc-uptime-002

TEST_GEN_PROGS += read

tools/testing/selftests/proc/proc-subset-pid.c

0 → 100644
+121 −0
Original line number Diff line number Diff line 
/*

 * 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;

}