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Corinna Vinschen e55f6ad713 Cygwin: fix process parent/child relationship after execve 
Commit 5a0f2c00aa "Cygwin: fork/exec: fix child process permissions"
removed the PROCESS_DUP_HANDLE handle permission of the parent process
handle in the child to avoid a security problem.

It turned out that this broke the following scenario: If a process forks
and then the parent execs, the child loses the ability to register the
parent's death.  To wit, after the parent died the child process does
not set its own PPID to 1 anymore.

The current exec mechanism copies required handle values (handles to
keep contact to the child processes) into the child_info for the
about-to-be-exec'ed process.  The exec'ed process is supposed to
duplicate these handles.  This fails, given that we don't allow the
exec'ed process PROCESS_DUP_HANDLE access to the exec'ing process since
commit 5a0f2c00aa.

The fix is to avoid the DuplicateHandle calls in the exec'ed process.

This patch sets the affected handles to "inheritable" in the exec'ing
process at exec time.  The exec'ed process just copies the handle values
and resets handle inheritance to "non-inheritable".  The exec'ing
process doesn't have to reset handle inheritance, it exits after setting
up the exec'ed process anyway.

Testcase: $ ssh-agent /bin/sleep 3

ssh-agent forks and the parent exec's sleep.  After sleep exits, `ps'
should show ssh-agent to have PPID 1, and eventually ssh-agent exits.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
 		2020-10-14 10:54:04 -04:00
..
CVSChangeLogs.old winsup: Move all old CVS Changelogs into CVSChangeLogs.old dir 2016-03-19 13:59:52 +01:00
cygserver Cygwin: fix GCC 8.3 'local external declaration' errors 2020-10-14 10:53:56 -04:00
cygwin Cygwin: fix process parent/child relationship after execve 2020-10-14 10:54:04 -04:00
doc Cygwin: document recent changes to format_proc_cpuinfo 2020-10-14 10:54:03 -04:00
lsaauth Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
testsuite Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
utils Cygwin: pty: Prevent the helper process from exiting by Ctrl-C. 2020-10-14 10:54:00 -04:00
CONTRIBUTORS Cygwin: Add J.H. van de Water to CONTRIBUTORS 2018-08-15 18:02:22 +02:00
COPYING
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COPYING.LIB Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
CYGWIN_LICENSE Clarify source file license in CYGWIN_LICENSE 2016-06-23 21:52:12 +02:00
Makefile.common Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
Makefile.in Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
README Fix typo and wrong URL in winsup/README 2016-05-24 10:25:18 +02:00
acinclude.m4
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aclocal.m4
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autogen.sh
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c++wrap
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ccwrap
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config.guess
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config.sub
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configure Cygwin: seteuid: disable unused funcs and lsaauth subdir 2019-01-28 10:24:18 +01:00
configure.ac Cygwin: seteuid: disable unused funcs and lsaauth subdir 2019-01-28 10:24:18 +01:00
configure.cygwin
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install-sh
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README 

THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESSED OR
IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

Cygwin documentation is available on the net at https://cygwin.com
You might especially be interested in

https://cygwin.com/faq/faq.html#faq.programming.building-cygwin