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3695eae5fe
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
24 lines
697 B
C
24 lines
697 B
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _UAPI_LINUX_WAIT_H
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#define _UAPI_LINUX_WAIT_H
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#define WNOHANG 0x00000001
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#define WUNTRACED 0x00000002
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#define WSTOPPED WUNTRACED
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#define WEXITED 0x00000004
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#define WCONTINUED 0x00000008
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#define WNOWAIT 0x01000000 /* Don't reap, just poll status. */
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#define __WNOTHREAD 0x20000000 /* Don't wait on children of other threads in this group */
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#define __WALL 0x40000000 /* Wait on all children, regardless of type */
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#define __WCLONE 0x80000000 /* Wait only on non-SIGCHLD children */
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/* First argument to waitid: */
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#define P_ALL 0
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#define P_PID 1
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#define P_PGID 2
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#define P_PIDFD 3
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#endif /* _UAPI_LINUX_WAIT_H */
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