On Sat, Mar 20, 2021 at 06:48:55PM +0300, Alexey Dobriyan wrote:
> 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.
Ops. Good catch! Looks good to me.
Acked-by: Alexey Gladkov <gladkov.alexey@xxxxxxxxx>
> Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
> ---
>
> tools/testing/selftests/proc/Makefile | 1
> tools/testing/selftests/proc/proc-subset-pid.c | 121 +++++++++++++++++++++++++
> 2 files changed, 122 insertions(+)
>
> --- a/tools/testing/selftests/proc/Makefile
> +++ b/tools/testing/selftests/proc/Makefile
> @@ -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
> new file mode 100644
> --- /dev/null
> +++ b/tools/testing/selftests/proc/proc-subset-pid.c
> @@ -0,0 +1,121 @@
> +/*
> + * Copyright (c) 2021 Alexey Dobriyan <adobriyan@xxxxxxxxx>
> + *
> + * 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;
> +}
>
--
Rgrds, legion
