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Cygwin: execve: reduce parent handle to non-inheritable SYNCHRONIZE 

Keeping an inheritable handle open results in that handle being
spilled over into grandchild processes, which is not desired.
Duplicate original parent handle into a non-inheritable one with
minimal SYNCHRONIZE permissions and close the original handle.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2019-01-29 20:37:00 +01:00
parent 5a0f2c00aa
commit 4d738e0f62
2 changed files with 25 additions and 8 deletions
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26
winsup/cygwin/dcrt0.cc
View File

@ -685,15 +685,31 @@ child_info_spawn::handle_spawn ()
ready (true);
/* Keep pointer to parent open if we've execed so that pid will not be reused.
Otherwise, we no longer need this handle so close it.
Need to do this after debug_fixup_after_fork_exec or DEBUGGING handling of
handles might get confused. */
if (type != _CH_EXEC && child_proc_info->parent)
if (child_proc_info->parent)
{
if (type == _CH_EXEC)
{
/* Keep pointer to parent open if we've execed so that pid will not be
reused. Try to Urther reduce permissions. */
HANDLE new_parent;
if (DuplicateHandle (GetCurrentProcess (), child_proc_info->parent,
GetCurrentProcess (), &new_parent,
SYNCHRONIZE, FALSE, 0))
{
CloseHandle (child_proc_info->parent);
child_proc_info->parent = new_parent;
}
}
else
{
/* Otherwise, we no longer need this handle so close it. Need to do
this after debug_fixup_after_fork_exec or DEBUGGING handling of
handles might get confused. */
CloseHandle (child_proc_info->parent);
child_proc_info->parent = NULL;
}
}
signal_fixup_after_exec ();
fixup_lockf_after_exec (type == _CH_EXEC);

3
winsup/cygwin/sigproc.cc
View File

@ -814,7 +814,8 @@ child_info::child_info (unsigned in_cb, child_info_types chtype,
allow the child to copy cygheap etc. from the parent to itself. If
we're forking, we also need handle duplicate access. */
parent = NULL;
DWORD perms = PROCESS_QUERY_LIMITED_INFORMATION | PROCESS_VM_READ;
DWORD perms = PROCESS_QUERY_LIMITED_INFORMATION | PROCESS_VM_READ
| SYNCHRONIZE;
if (type == _CH_FORK)
{
perms |= PROCESS_DUP_HANDLE;