Hi,
This is new version of the patch. I hope last one.
http://cr.openjdk.java.net/~sgabdura/8057564/webrev.03/
I also spent time on Sunday with that issue. I tried to find another
solution, but did not succeed.
All my attempts of applying of modified Security Descriptor to existing
Named Pipe failed with error "Access denied"
BR,
Sergey
On 22.09.2014 0:30, Markus Grönlund wrote:
Hi again Sergey,
I have spent some time in an attempt to figure out how we could accomplish this
- I must say it has been quite frustrating.
I was hoping we could only update the pSacl info with the
SYSTEM_MANDATORY_LABEL_ACE field set to Medium. This is not straightforward. I
have also tried to accomplish this by Windows impersonation, and updating the
impersonation token - this works, but it requires quite a lot of
infrastructure. In addition, if the thread is already impersonating, we need to
restore the original token - and by setting the IntegrityLevel to Medium for
the impersonation token one looses the SeImpersonatePrivilege which means I
cannot do SetThreadToken() again for the original impersonation...messy.
I then thought about using SDDL just as you have done, but only updating the
Sacl info using SetSecurityInfo on the already created named pipe. This works,
but it seems this triggered another issue (manifests as still hanging) - even
though the integrity level is now set to Medium, the client have problem
connecting (looks like this also requires easing up on the actual Discretionary
ACL (just as you have done).
So I ended up circling back to what you have in your second patch - if we are
going to solve this proper, we need to spend quite a lot of time on it.
I initially thought we should also state the Mandatory Label information in the
SDDL, mainly for readability and rational purposes like:
TCHAR *szSD = TEXT("D:") // Discretionary ACL
TEXT("(A;OICI;GRGW;;;WD)") // Allow read/write/execute to
everybody
TEXT("(A;OICI;GA;;;SY)") // Allow full control to system
TEXT("(A;OICI;GA;;;BA)") // Allow full control to
administrators
TEXT("S:") // System ACL
TEXT("(ML;;NW;;;ME)"); // Mandatory Integrity Label,
No-WriteUp Policy, Medium Mandatory Level
However, after some thought I changed my mind on this:
Only Vista and later support the Mandatory Integrity Label, and if we include
it we need to check conditionally. Somehow, the default when creating a
securable object with you own Security Descriptor (instead of inheriting either
the primary process or impersonation token) is that you default to Medium
Mandatory Level (I don’t know if this just luck, but it seems to be that way,
even for High Level process tokens).
So to avoid conditional checks I suggest not including this:
("S:") // System ACL
TEXT("(ML;;NW;;;ME)"); // Mandatory Integrity Label,
No-WriteUp Policy, Medium Mandatory Level
Which is also what you already have in your patch.
Maybe you could include a comment about the assumption that we expect to "get"
Medium Mandatory Level by creating our own Security Descriptor? That way we can keep
track of the rationale, and if MSFT changes this.
I then just have one additional comment/change request:
291: LocalFree(&(sa.lpSecurityDescriptor));
This should be:
291: LocalFree(sa.lpSecurityDescriptor);
With that change and some comment to the Medium Mandatory Level I am ok with
your suggestion.
Thanks a lot for fixing this.
Many thanks
Markus
-----Original Message-----
From: Markus Grönlund
Sent: den 19 september 2014 14:46
To: Sergey Gabdurakhmanov
Cc: Alexey Utkin; serviceability-dev@openjdk.java.net
Subject: RE: URGENT: RE: RFR(XS): 8057564: JVM hangs at getAgentProperties
after attaching to VM with lower IntegrityLevel
Hi Sergey,
This is not exactly what I had in mind - we have updated the DACL to provide
some explicit security (from a NULL DACL which allows everyone everything), so
that’s good. But..
I was hoping we could just keep the default security for the DACL (no need to
change this, pass a NULL to CreateNamedPipe() is fine (will inherit process
token)).
Then we should just focus on manipulating the SidStart field in the
SYSTEM_MANDATORY_LABEL_ACE structure in the SACL (not the DACL).
Maybe you tried this already?
Cheers
Markus
-----Original Message-----
From: Sergey Gabdurakhmanov
Sent: den 19 september 2014 14:34
To: Mattis Castegren; serviceability-dev@openjdk.java.net; Markus Grönlund;
Staffan Larsen; Christian Törnqvist; Markus Grönlund; Alexey Utkin; Dmitry
Samersoff
Subject: Re: URGENT: RE: RFR(XS): 8057564: JVM hangs at getAgentProperties
after attaching to VM with lower IntegrityLevel
Hi,
New version of the fix for review:
http://cr.openjdk.java.net/~sgabdura/8057564/webrev.02/
Now I add security descriptor with read/write permissions to everybody and full
control to system and administrators.
BR,
Sergey
On 17.09.2014 18:03, Mattis Castegren wrote:
Also adding Christian, who is both a reviewer AND knows windows.
This is a very critical customer bug, and we have a hard deadline of next week.
Kind Regards
/Mattis
-----Original Message-----
From: Mattis Castegren
Sent: den 17 september 2014 07:08
To: Sergey Gabdurakhmanov; serviceability-dev@openjdk.java.net; Markus
Grönlund; Staffan Larsen
Cc: Mattis Castegren
Subject: RE: RFR(XS): 8057564: JVM hangs at getAgentProperties after
attaching to VM with lower IntegrityLevel
Hi
This is urgent for a customer case, so we would need the second review. Dmitry
was ok with the fix. Sergey, you also got some additional review from someone
who was not an official reviewer, right? Could you paste those comments?
If no one on this alias feels comfortable with reviewing this fix, any ideas on
someone else who can do it and who is has reviewer status? Maybe someone from
another team with a lot of Windows experience?
Kind Regards
/Mattis
-----Original Message-----
From: Sergey Gabdurakhmanov
Sent: den 16 september 2014 12:56
To: serviceability-dev@openjdk.java.net
Subject: Re: RFR(XS): 8057564: JVM hangs at getAgentProperties after
attaching to VM with lower IntegrityLevel
Hi,
I need a second approval for the fix integration.
Can somebody else review the patch?
BR,
Sergey
On 12.09.2014 17:34, Dmitry Samersoff wrote:
Sergey,
Looks good for me.
-Dmitry
On 2014-09-12 12:46, Sergey Gabdurakhmanov wrote:
Dmitry,
New patch:
http://cr.openjdk.java.net/~sgabdura/8057564/webrev.01/
My answers:
1. You should not free lpSecurityDescriptor if it's null (ll.291)
I checked MSDN
http://msdn.microsoft.com/en-us/library/windows/desktop/aa366730%28v
=vs.85%29.aspx "If the /hMem/ parameter is *NULL*, *LocalFree*
ignores the parameter and returns *NULL*."
2. It's better to re-arrange code a bit:
if InitializeSecurityDescriptor or SetSecurityDescriptorDacl fails,
free lpSecurityDescriptor immediately and continue with
lpSecurityDescriptor == NULL
Done.
3. Make sure it works on all supported platforms: this code rise
minimal server version to windows 2003 server.
In Windows 2003 server my fix will create a new security attributes.
If SetSecurityDescriptorDacl or InitializeSecurityDescriptor will
return false on Windows XP then my patch will pass NULL to
CreateNamedPipe and the code will use default security descriptor.
BR,
Sergey
On 11.09.2014 16:16, Dmitry Samersoff wrote:
Sergey,
1. You should not free lpSecurityDescriptor if it's null (ll.291)
2. It's better to re-arrange code a bit:
if InitializeSecurityDescriptor or SetSecurityDescriptorDacl fails,
free lpSecurityDescriptor immediately and continue with
lpSecurityDescriptor == NULL
3. Make sure it works on all supported platforms: this code rise
minimal server version to windows 2003 server.
-Dmitry
On 2014-09-11 15:49, Sergey Gabdurakhmanov wrote:
Hi,
Could I please have a review of this small fix.
webrev: http://cr.openjdk.java.net/~sgabdura/8057564/webrev.00/
bug: https://jbs.oracle.com/bugs/browse/JDK-8057564
Problem description:
On Windows 7 with User Account Control (UAC) enabled, JVM hangs at
getAgentProperties or getSystemProperties after attaching from a "high"
IntegrityLevel JVM to a "medium" IntegrityLevel JVM, using Attach API:
attachedVM = com.sun.tools.attach.VirtualMachine.attach(pid);
final Properties systemProperties =
attachedVM.getSystemProperties();
Root cause:
In WindowsVirtualMachine.attach is implemented with named pipes.
If named pipe was created with default security properties then
windows will not allow process with"medium" IntegrityLevel to be
attached to a processwith "high" IntegrityLevel.
Solution:
Create security properties that allow requested connection.
I'm going to push this fix into JDK9, 8 and 7.
BR,
Sergey
