[Bug nptl/10563] New: supplementary groups are not shared between (p)threads

[Bug nptl/10563] New: supplementary groups are not shared between (p)threads

[kamil dot 76934 at iskra dot name]

I noticed that supplementary groups (getgroups(2)/setgroups(2)) are not shared
between the threads in a multithreaded program.  I would expect that since
[e]uid and [e]gid are, so should the supplementary groups?  I checked the source
and I can see that set*id() calls use the setxid API to synchronize the ids
between the threads, but setgroups() does not do that; I guess that's the
problem.  I didn't try to compile the latest version, but the source is the same
in that respect...

This is with kernel 2.6.30, gcc 4.3.2, binutils 2.18, but I don't think this
matters all that much, as I first saw it on a completely different platform
(PPC64 SLES 10).

I'll attach a self-contained testcode.  It needs to be run as root.  I'm getting
the following output:

"Initial groups:
0, 1, 2, 3, 4, 6, 10, 11, 20, 26, 27

Launched a new thread

Changing groups in the main thread...

Main thread groups:
12345

Launched thread groups:
0, 1, 2, 3, 4, 6, 10, 11, 20, 26, 27"

Instead, I would expect the last line to be "12345".

-- 
           Summary: supplementary groups are not shared between (p)threads
           Product: glibc
           Version: 2.9
            Status: NEW
          Severity: normal
          Priority: P2
         Component: nptl
        AssignedTo: drepper at redhat dot com
        ReportedBy: kamil dot 76934 at iskra dot name
                CC: glibc-bugs at sources dot redhat dot com
  GCC host triplet: x86_64-pc-linux-gnu


http://sourceware.org/bugzilla/show_bug.cgi?id=10563

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[Bug nptl/10563] supplementary groups are not shared between (p)threads

[kamil dot 76934 at iskra dot name]

------- Additional Comments From kamil dot 76934 at iskra dot name  2009-08-25 22:51 -------
Created an attachment (id=4151)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4151&action=view)
self-contained testcase


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http://sourceware.org/bugzilla/show_bug.cgi?id=10563

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[Bug nptl/10563] supplementary groups are not shared between (p)threads

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=10563

--- Comment #6 from Florian Weimer <fweimer at redhat dot com> ---
Fixed in commit 70181fddf1467996bea393d13294ffe76b8a0853, which went into glibc
2.13.

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[Bug nptl/10563] supplementary groups are not shared between (p)threads

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=10563

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com
              Flags|                            |security+

--- Comment #5 from Florian Weimer <fweimer at redhat dot com> ---
This should probably treated as a security issue because it can interact with
relinquishing privileges.

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[Bug nptl/10563] supplementary groups are not shared between (p)threads

[drepper.fsp at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=10563

Ulrich Drepper <drepper.fsp at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #4 from Ulrich Drepper <drepper.fsp at gmail dot com> 2011-01-14 13:42:57 UTC ---
I checked in some changes.

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[Bug nptl/10563] supplementary groups are not shared between (p)threads

[mark at heily dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=10563

--- Comment #3 from Mark Heily <mark at heily dot com> 2011-01-11 02:11:32 UTC ---
Created attachment 5188
  --> http://sourceware.org/bugzilla/attachment.cgi?id=5188
Additional testcase

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[Bug nptl/10563] supplementary groups are not shared between (p)threads

[mark at heily dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=10563

--- Comment #2 from Mark Heily <mark at heily dot com> 2011-01-11 01:51:47 UTC ---
Created attachment 5187
  --> http://sourceware.org/bugzilla/attachment.cgi?id=5187
use INLINE_SETXID_SYSCALL for setgroups()

The attached patch converts setgroups() to use INLINE_SETXID_SYSCALL which
should hopefully fix the problem. I havn't tested it, and don't know if there
is anything else that needs to be done.

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