On Fri, 2006-05-26 at 13:04 +0200, Enrico Scholz wrote:
Michael_E_Brown(a)dell.com (Michael E Brown) writes:
> Here is a resend/consolidation of the autocache patches from last week.
> I have combined the patches sent last week. It now defaults to gzip
> format. I have also made the following fixes:
> + check_dir_allowed (rootsdir, argv);
When you do security checks, then please make them correctly. Everything
else will give a wrong feeling about security:
I welcome the feedback, thanks much.
| operate_in_dir(<dir>); // tar ...
Dir always has to be under /var/lib/mock/. It is not possible for
unprivileged users to create symlinks here.
I suppose the symlink attack could be done by somebody in the mock
1) mock -r CFG some.src.rpm #to force creation of builddir with
ownership by me.
2) cd /var/lib/mock/CFG/root/builddir/
3) ln -s / blastroot
4) mock-helper unpack /var/lib/mock/CFG/root/builddir/blastroot
I believe that the fix for this would be to add a check to ensure that
the tarball is always sourced from /var/lib/mock/root-cache/ and that
the perms are correct. Feedback?
opens always a window for symlink attacks. Better do
| operate_in_dir("."); // tar ...
The security of 'tar' operations is another question; extraction can
be made secure by extracting into a private dir and doing an atomic
rename(2) then. ATM, I do not see a way how to implement tarball
Make sure we are always tarring /var/lib/mock/CFG/root and always place
the tar under /var/lib/mock/root-cache.
Users in group 'mock' would not have sufficient perms to do anything
harmful under this dir.
* you should check permissions of the tar-file; else, user can provide
e.g. a public writable /dev/kmem device in the tarball
Ok, the question remains whether such checks (inclusive check_dir_allowed())
are needed overall. 'mock' gives practically root rights to everybody in the
Personally, I think they should be there. It makes things much more
For a patch, I could change both pack and unpack to only take the file
name and config name. It would then always look for or create the tar
under /var/lib/mock/root-cache/, and it would only ever tar or untar