SELinux for mock
Daniel J Walsh
dwalsh at redhat.com
Tue May 3 19:36:02 UTC 2011
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On 05/03/2011 03:32 PM, Piscium wrote:
> On 2 May 2011 14:06, Kevin Fenzi <kevin at scrye.com> wrote:
>> On Sun, 1 May 2011 19:29:50 +0100
>> Piscium <groknok at gmail.com> wrote:
>>
>>> I like to rebuild a number of Fedora source packages for performance
>>> and some tweaking.
>>>
>>> In the past I have used rpmbuild for that purpose, but this weekend I
>>> started using mock.
>>>
>>> So far I built about a dozen source packages successfully, but then
>>> got a SELinux snag when building glibc (I am using the targeted policy
>>> on F14).
>>>
>>> The wiki has instructions on how to set SELinux for mock:
>>> http://fedoraproject.org/wiki/Using_Mock_to_test_package_builds#SELinux_policy_module_for_mock
>>>
>>> I followed the instructions but the result of running Make was
>>> different from the expected, there was an error. [1].
>>>
>>> My question is if the policy files of the wiki page are current? They
>>> are three years old, which is a long time in dog years or Fedora
>>> years!
>>
>> Right. Thats out of date. As far as I know you don't need to do
>> anything special anymore. Mock handles it all.
>>
>> Just run mock out of the box? Does it fail? If so, how?
>
> I am not sure what you mean by "just" "out of the box". I ran mock
> with the "--no-clean" option to save the time to download and install
> the whole chroot environment. I did "mock --update" before, and I
> changed the default optflags. Other than that it was a pristine
> chroot.
>
> Yesterday I built glibc with rpmbuild (i. e. without mock) and got the
> same SELinux alert as with mock. Some months ago on F13 I built glibc
> with rpmbuild without an alert, so it seems that something changed
> between F13 and F14, possibly in glibc.
>
> As I said, while glibc self-tests failed, the whole build succeeded,
> so yesterday I installed the glibc packages that I built and so far
> everything seems fine.
>
> I am pasting below the alert message I got from SELinux. I kept the
> mock build log that shows the failed tests (some of them failed while
> testing execstack). If anybody is interested I can upload it somewhere
> (I am not sure if I can email to the list, can I?).
>
> This makes me wonder if the Koji servers that do the Fedora builds
> have SELinux enabled?
>
> -----------------
>
> SELinux is preventing
> /builddir/build/BUILD/glibc-2.13/build-i686-linuxnptl/elf/ld.so from
> using the execstack access on a process.
>
> ***** Plugin allow_execstack (53.1 confidence) suggests ********************
>
> If you believe that
> None
> should not require execstack
> Then you should clear the execstack flag and see if
> /builddir/build/BUILD/glibc-2.13/build-i686-linuxnptl/elf/ld.so works
> correctly.
> Report this as a bug on None.
> You can clear the exestack flag by executing:
> Do
> execstack -c None
>
> ***** Plugin catchall_boolean (42.6 confidence) suggests *******************
>
> If you want to allow unconfined executables to make their stack
> executable. This should never, ever be necessary. Probably indicates
> a badly coded executable, but could indicate an attack. This
> executable should be reported in bugzilla
> Then you must tell SELinux about this by enabling the 'allow_execstack' boolean.
> Do
> setsebool -P allow_execstack 1
>
> ***** Plugin catchall (5.76 confidence) suggests ***************************
>
> If you believe that ld.so should be allowed execstack access on
> processes labeled unconfined_t by default.
> Then you should report this as a bug.
> You can generate a local policy module to allow this access.
> Do
> allow this access for now by executing:
> # grep ld-linux.so.2 /var/log/audit/audit.log | audit2allow -M mypol
> # semodule -i mypol.pp
>
> Additional Information:
> Source Context unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1
> 023
> Target Context unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1
> 023
> Target Objects Unknown [ process ]
> Source ld-linux.so.2
> Source Path /builddir/build/BUILD/glibc-2.13/build-i686-linuxn
> ptl/elf/ld.so
> Port <Unknown>
> Host d3000
> Source RPM Packages
> Target RPM Packages
> Policy RPM selinux-policy-3.9.7-40.fc14
> Selinux Enabled True
> Policy Type targeted
> Enforcing Mode Enforcing
> Host Name d3000
> Platform Linux d3000 2.6.35.12-90.fc14.i686 #1 SMP Fri Apr
> 22 16:14:44 UTC 2011 i686 i686
> Alert Count 8
> First Seen Sun 01 May 2011 17:38:44 IST
> Last Seen Sun 01 May 2011 18:14:25 IST
> Local ID df1866d2-1dcb-4bd9-bcc0-88a350597d97
>
> Raw Audit Messages
> type=AVC msg=audit(1304270065.850:25864): avc: denied { execstack }
> for pid=967 comm="ld-linux.so.2"
> scontext=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> tcontext=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> tclass=process
>
>
> type=SYSCALL msg=audit(1304270065.850:25864): arch=i386
> syscall=mprotect per=8 success=no exit=EACCES a0=bf924000 a1=1000
> a2=1000007 a3=bf9248c8 items=0 ppid=966 pid=967 auid=1000 uid=1000
> gid=490 euid=1000 suid=1000 fsuid=1000 egid=490 sgid=490 fsgid=490
> tty=pts2 ses=1 comm=ld-linux.so.2
> exe=/builddir/build/BUILD/glibc-2.13/build-i686-linuxnptl-nosegneg/elf/ld.so
> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)
>
> Hash: ld-linux.so.2,unconfined_t,unconfined_t,process,execstack
>
> audit2allow
>
> #============= unconfined_t ==============
> #!!!! This avc can be allowed using the boolean 'allow_execstack'
>
> allow unconfined_t self:process execstack;
>
> audit2allow -R
>
> #============= unconfined_t ==============
> #!!!! This avc can be allowed using the boolean 'allow_execstack'
>
> allow unconfined_t self:process execstack;
You should report this as a bug in gcc.
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