[newlib-cygwin] Cygwin: setrlimit: Add a permission check

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=670beaed0216aa59603501e8f14e1f04b138bc47

commit 670beaed0216aa59603501e8f14e1f04b138bc47
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Tue Nov 30 12:48:34 2021 +0100

    Cygwin: setrlimit: Add a permission check
    
    If the incoming soft limit is less restrictive than the current
    hard limit, bail out with EPERM.  Given the previous sanity check,
    this implies trying to raise the hard limit.  While, theoretically,
    this should be allowed for privileged processes, Windows has no
    matching concept in terms of job limits
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/resource.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/winsup/cygwin/resource.cc b/winsup/cygwin/resource.cc
index 46d74b984..c4c79ca6f 100644
--- a/winsup/cygwin/resource.cc
+++ b/winsup/cygwin/resource.cc
@@ -261,6 +261,12 @@ setrlimit (int resource, const struct rlimit *rlp)
 	  __leave;
 	}
 
+      if (rlp->rlim_cur > oldlimits.rlim_max)
+	{
+	  set_errno (EPERM);
+	  __leave;
+	}
+
       switch (resource)
 	{
 	case RLIMIT_AS: