linux/include
Christian Brauner 3695eae5fe
pidfd: add P_PIDFD to waitid()
This adds the P_PIDFD type to waitid().
One of the last remaining bits for the pidfd api is to make it possible
to wait on pidfds. With P_PIDFD added to waitid() the parts of userspace
that want to use the pidfd api to exclusively manage processes can do so
now.

One of the things this will unblock in the future is the ability to make
it possible to retrieve the exit status via waitid(P_PIDFD) for
non-parent processes if handed a _suitable_ pidfd that has this feature
set. This is similar to what you can do on FreeBSD with kqueue(). It
might even end up being possible to wait on a process as a non-parent if
an appropriate property is enabled on the pidfd.

With P_PIDFD no scoping of the process identified by the pidfd is
possible, i.e. it explicitly blocks things such as wait4(-1), wait4(0),
waitid(P_ALL), waitid(P_PGID) etc. It only allows for semantics
equivalent to wait4(pid), waitid(P_PID). Users that need scoping should
rely on pid-based wait*() syscalls for now.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
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: 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/20190727222229.6516-2-christian@brauner.io
2019-08-01 21:49:46 +02:00
..
acpi It's been a relatively busy cycle for docs: 2019-07-09 12:34:26 -07:00
asm-generic Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2019-07-17 13:13:41 -07:00
clocksource
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2019-07-08 20:57:08 -07:00
drm drm fixes for -rc1: 2019-07-19 12:29:43 -07:00
dt-bindings ARM: Device-tree updates 2019-07-19 17:19:24 -07:00
keys request_key improvements 2019-07-08 19:19:37 -07:00
kvm KVM: arm/arm64: Support chained PMU counters 2019-07-05 13:56:22 +01:00
linux pidfd: add P_PIDFD to waitid() 2019-08-01 21:49:46 +02:00
math-emu
media media updates for v5.3-rc1 2019-07-09 09:47:22 -07:00
misc powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
net tcp: fix tcp_set_congestion_control() use from bpf hook 2019-07-18 20:33:48 -07:00
pcmcia It's been a relatively busy cycle for docs: 2019-07-09 12:34:26 -07:00
ras
rdma RDMA/core: Make rdma_counter.h compile stand alone 2019-07-09 09:44:47 -03:00
scsi SCSI fixes on 20190720 2019-07-20 10:04:58 -07:00
soc ARM: SoC-related driver updates 2019-07-19 17:13:56 -07:00
sound ALSA: hda - Don't resume forcibly i915 HDMI/DP codec 2019-07-16 22:46:13 +02:00
target
trace NFS client updates for Linux 5.3 2019-07-18 14:32:33 -07:00
uapi pidfd: add P_PIDFD to waitid() 2019-08-01 21:49:46 +02:00
vdso
video drm main pull request for v5.3-rc1 (sans mm changes) 2019-07-15 19:04:27 -07:00
xen xen: remove tmem driver 2019-07-17 08:09:58 +02:00
Kbuild kbuild: update compile-test header list for v5.3-rc1 2019-07-20 11:19:29 +09:00