selftest: pidfd: Omit long and repeating outputs

An output message:

> # # waitpid WEXITSTATUS=0

will be printed for 30,000+ times in the `pidfd_test` selftest, which
does not seem ideal. This patch removes the print logic in the
`wait_for_pid` function, so each call to this function does not output
a line by default. Any existing call sites where the extra line might
be beneficial have been modified to include extra print statements
outside of the function calls.

Signed-off-by: Ziqi Zhao <astrajoan@yahoo.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

pidfd: fix test failure due to stack overflow on some arches

When running the pidfd_fdinfo_test on arm64, it fails for me. After some
digging, the reason is that the child exits due to SIGBUS, because it
overflows the 1024 byte stack we've reserved for it.

To fix the issue, increase the stack size to 8192 bytes (this number is
somewhat arbitrary, and was arrived at through experimentation -- I kept
doubling until the failure no longer occurred).

Also, let's make the issue easier to debug. wait_for_pid() returns an
ambiguous value: it may return -1 in all of these cases:

1. waitpid() itself returned -1
2. waitpid() returned success, but we found !WIFEXITED(status).
3. The child process exited, but it did so with a -1 exit code.

There's no way for the caller to tell the difference. So, at least log
which occurred, so the test runner can debug things.

While debugging this, I found that we had !WIFEXITED(), because the
child exited due to a signal. This seems like a reasonably common case,
so also print out whether or not we have WIFSIGNALED(), and the
associated WTERMSIG() (if any). This lets us see the SIGBUS I'm fixing
clearly when it occurs.

Finally, I'm suspicious of allocating the child's stack on our stack.
man clone(2) suggests that the correct way to do this is with mmap(),
and in particular by setting MAP_STACK. So, switch to doing it that way
instead.

Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tests: add waitid() tests for non-blocking pidfds

Verify that the PIDFD_NONBLOCK flag works with pidfd_open() and that
waitid() with a non-blocking pidfd returns EAGAIN:

TAP version 13
1..3
# Starting 3 tests from 1 test cases.
# RUN global.wait_simple ...
# OK global.wait_simple
ok 1 global.wait_simple
# RUN global.wait_states ...
# OK global.wait_states
ok 2 global.wait_states
# RUN global.wait_nonblock ...
# OK global.wait_nonblock
ok 3 global.wait_nonblock
# PASSED: 3 / 3 tests passed.
# Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: linux-kselftest@vger.kernel.org
Link: https://lore.kernel.org/r/20200902102130.147672-5-christian.brauner@ubuntu.com

tests: add CLONE_NEWTIME setns tests

Now that pidfds support CLONE_NEWTIME as well enable testing them in the
setns() testuite.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Dmitry Safonov <dima@arista.com>
Cc: Andrei Vagin <avagin@gmail.com>
Link: https://lore.kernel.org/r/20200706154912.3248030-5-christian.brauner@ubuntu.com

tests: test for setns() EINVAL regression

Verify that setns() reports EINVAL when an fd is passed that refers to an
open file but the file is not a file descriptor useable to interact with
namespaces.

Cc: Jan Stancek <jstancek@redhat.com>
Cc: Cyril Hrubis <chrubis@suse.cz>
Link: https://lore.kernel.org/lkml/20200615085836.GR12456@shao2-debian
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

selftests: add pid namespace ENOMEM regression test

We recently regressed (cf. [1] and its corresponding fix in [2]) returning
ENOMEM when trying to create a process in a pid namespace whose init
process/child subreaper has already died. This has caused confusion at
least once before that (cf. [3]). Let's add a simple regression test to
catch this in the future.

[1]: 49cb2fc42ce4 ("fork: extend clone3() to support setting a PID")
[2]: b26ebfe12f34 ("pid: Fix error return value in some cases")
[3]: 35f71bc0a09a ("fork: report pid reservation failure properly")
Cc: Corey Minyard <cminyard@mvista.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Adrian Reber <areber@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

test: Add test for pidfd getfd

The following tests:
* Fetch FD, and then compare via kcmp
* Make sure getfd can be blocked by blocking ptrace_may_access
* Making sure fetching bad FDs fails
* Make sure trying to set flags to non-zero results in an EINVAL

Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20200107175927.4558-5-sargun@sargun.me
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

tests: move common definitions and functions into pidfd.h

Move definitions and functions used across different pidfd tests into
pidfd.h header.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Christian Brauner <christian@brauner.io>
Link: https://lore.kernel.org/r/20190726162226.252750-1-surenb@google.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

pidfd: add pidfd_wait tests

Add tests for pidfd_wait() and CLONE_WAIT_PID:
- test that waitid(P_PIDFD) fails on /proc/<pid>
- test that waitid(P_PIDFD) fails on /dev/null
- test that waitid(P_PIDFD) can wait on a pidfd
- test that waitid(P_PIDFD) can wait on a pidfd and return siginfo_t
- test that waitid(P_PIDFD) works with WEXITED
- test that waitid(P_PIDFD) works with WSTOPPED
- test that waitid(P_PIDFD) works with WUNTRACED
- test that waitid(P_PIDFD) works with WCONTINUED
- test that waitid(P_PIDFD) works with WNOWAIT
- test that waitid(P_PIDFD)works with WNOHANG

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20190727222229.6516-3-christian@brauner.io

tests: add pidfd_open() tests

This adds testing for the new pidfd_open() syscalls. Specifically, we test:
- that no invalid flags can be passed to pidfd_open()
- that no invalid pid can be passed to pidfd_open()
- that a pidfd can be retrieved with pidfd_open()
- that the retrieved pidfd references the correct pid

Signed-off-by: Christian Brauner <christian@brauner.io>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jann Horn <jannh@google.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org