5 Commits

Author SHA1 Message Date
jonathan
5ecd1c9d40 Add experimental support for process descriptors
A "process descriptor" file descriptor is used to manage processes
without using the PID namespace. This is required for Capsicum's
Capability Mode, where the PID namespace is unavailable.

New system calls pdfork(2) and pdkill(2) offer the functional equivalents
of fork(2) and kill(2). pdgetpid(2) allows querying the PID of the remote
process for debugging purposes. The currently-unimplemented pdwait(2) will,
in the future, allow querying rusage/exit status. In the interim, poll(2)
may be used to check (and wait for) process termination.

When a process is referenced by a process descriptor, it does not issue
SIGCHLD to the parent, making it suitable for use in libraries---a common
scenario when using library compartmentalisation from within large
applications (such as web browsers). Some observers may note a similarity
to Mach task ports; process descriptors provide a subset of this behaviour,
but in a UNIX style.

This feature is enabled by "options PROCDESC", but as with several other
Capsicum kernel features, is not enabled by default in GENERIC 9.0.

Reviewed by: jhb, kib
Approved by: re (kib), mentor (rwatson)
Sponsored by: Google Inc
2011-08-18 22:51:30 +00:00
dchagin
7309a9eb12 Do not clobber %rdx.
Before calling vfork() syscall the linux user-space stores the current PID
in the %rdx and restore it when the parent process will leave the kernel.
2011-02-20 07:58:30 +00:00
dchagin
bd20f71621 Slightly rewrite linux_fork:
1) Remove bogus error checking.
2) A new process exit from kernel through fork_trampoline(),
   so remove bogus check.
2011-02-12 20:16:25 +00:00
dchagin
9cf49ae032 Remove bogus include <machine/frame.h> 2011-02-12 19:14:57 +00:00
dchagin
9f708ad0aa Move linux_clone(), linux_fork(), linux_vfork() to a MI path. 2011-02-12 18:17:12 +00:00