First srpm built with new mock launcher + modified mock.py

[Clark Williams]

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I actually built an SRPM last night, using a moderately hacked mock.py
with the new mock launcher.

After figuring out what Michael meant wrt uid/gid manipulation, I went
into mock.py and added two methods to the Root class:

elevate() - change uid to the effective uid (i.e. root)
drop() - change uid back to real uid (i.e. your user id)

I modified the startup code to save off effective and real uids and to
set the realgid to the mock group. I then bracketed calls to "do" that
require privileges (e.g. chroot, mount, etc.) to look like this:

self.elevate()
    self.do(<privileged command>)
    self.drop()

I had an elinks srpm hanging around and fired off a mock build of that
package, which after finding a couple of calls that needed privileges,
worked (I'm always amazed when that happens). Admittedly it's not a
complex build, but it's a start.

One thing I'm puzzled about is that the build worked on a system
running SELinux and currently the SELinux preload isn't being done.
Anyone have an example build that bombs because of SELinux when the
LD_PRELOAD isn't done?

I need to do a little tidying up of mock.py. The cache stuff is
completely broken because the actual pack/unpack logic is in the
now-defunct mock-helper. I got started moving it into mock.py, but was
overcome with sleepiness last night and didn't finish.  I'll try and
send out a mock.py to the list today (or would you rather have a
patch?). Just wanted some eyeballs on it to see if it's going in the
right direction.

Clark
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[Michael E Brown]

Recommend:
    do_elevated()
    do_asuser()

To ensure that all calls are easy-to-audit. The elevate() and drop()
calls should be properly bracketed with a try/finally so that exceptions
do not interfere with dropping privs.

Along these lines, I also thought that the mount()/umount() code would
be best if it were pushed into the do() function.

As for the new mock, I would say patch format to the list is best for
small changes. 
--
Michael
> -----Original Message-----
> From: [e-mail] 
> [mailto:[e-mail]] On Behalf Of 
> Clark Williams
> Sent: Thursday, June 15, 2006 9:19 AM
> To: Discussion of Fedora build system
> Subject: First srpm built with new mock launcher + modified mock.py
>
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> Hash: SHA1
>
> I actually built an SRPM last night, using a moderately 
> hacked mock.py with the new mock launcher.
>
> After figuring out what Michael meant wrt uid/gid 
> manipulation, I went into mock.py and added two methods to 
> the Root class:
>
> elevate() - change uid to the effective uid (i.e. root)
> drop() - change uid back to real uid (i.e. your user id)
>
> I modified the startup code to save off effective and real 
> uids and to set the realgid to the mock group. I then 
> bracketed calls to "do" that require privileges (e.g. chroot, 
> mount, etc.) to look like this:
> self.elevate()
> self.do(<privileged command>)
> self.drop()
>
> I had an elinks srpm hanging around and fired off a mock 
> build of that package, which after finding a couple of calls 
> that needed privileges, worked (I'm always amazed when that 
> happens). Admittedly it's not a complex build, but it's a start.
>
> One thing I'm puzzled about is that the build worked on a 
> system running SELinux and currently the SELinux preload 
> isn't being done.
> Anyone have an example build that bombs because of SELinux 
> when the LD_PRELOAD isn't done?
>
> I need to do a little tidying up of mock.py. The cache stuff 
> is completely broken because the actual pack/unpack logic is 
> in the now-defunct mock-helper. I got started moving it into 
> mock.py, but was overcome with sleepiness last night and 
> didn't finish.  I'll try and send out a mock.py to the list 
> today (or would you rather have a patch?). Just wanted some 
> eyeballs on it to see if it's going in the right direction.
>
> Clark
>
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> =5hTr
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>
> --
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> [e-mail]
> https://www.redhat.com/mailman/listinfo/fedora-buildsys-list

[Clark Williams]

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[e-mail] wrote:
> Recommend:
>     do_elevated()
>     do_asuser()
>
> To ensure that all calls are easy-to-audit. The elevate() and drop()
> calls should be properly bracketed with a try/finally so that exceptions
> do not interfere with dropping privs.

So essentially we won't call "do" directly from a command anymore,
we'll call do_<how> and that's where we'll elevate (or not)? Yeah, I
can go with that. And yes, a try/finally was on the agenda...
> Along these lines, I also thought that the mount()/umount() code would
> be best if it were pushed into the do() function.

I haven't looked at that, so have no opinion. I'll look at it while
I'm working on the above.
> As for the new mock, I would say patch format to the list is best for
> small changes.

I'm on the fence as to whether this is a small to change to mock.py.
Tell you what, I'll add the do_elevated and do_asuser wrappers, put
that in place and send a diff. If it's too messy I can always send the
source.

Clark
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