Re: [RFC PATCH v2 0/9] Add LSM access controls and auditing to io_uring

Paul Moore
2021-08-26T01:35:02Z

On Wed, Aug 25, 2021 at 9:16 PM Richard Guy Briggs <rgb@redhat.com> wrote:
>
> On 2021-08-24 16:57, Richard Guy Briggs wrote:
> > On 2021-08-11 16:48, Paul Moore wrote:
> > > Draft #2 of the patchset which brings auditing and proper LSM access
> > > controls to the io_uring subsystem. The original patchset was posted
> > > in late May and can be found via lore using the link below:
> > >
> > > https://lore.kernel.org/linux-security-module/162163367115.8379.8459012634106035341.stgit@sifl/
> > >
> > > This draft should incorporate all of the feedback from the original
> > > posting as well as a few smaller things I noticed while playing
> > > further with the code. The big change is of course the selective
> > > auditing in the io_uring op servicing, but that has already been
> > > discussed quite a bit in the original thread so I won't go into
> > > detail here; the important part is that we found a way to move
> > > forward and this draft captures that. For those of you looking to
> > > play with these patches, they are based on Linus' v5.14-rc5 tag and
> > > on my test system they boot and appear to function without problem;
> > > they pass the selinux-testsuite and audit-testsuite and I have not
> > > noticed any regressions in the normal use of the system. If you want
> > > to get a copy of these patches straight from git you can use the
> > > "working-io_uring" branch in the repo below:
> > >
> > > git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux.git
> > > https://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux.git
> > >
> > > Beyond the existing test suite tests mentioned above, I've cobbled
> > > together some very basic, very crude tests to exercise some of the
> > > things I care about from a LSM/audit perspective. These tests are
> > > pretty awful (I'm not kidding), but they might be helpful for the
> > > other LSM/audit developers who want to test things:
> > >
> > > https://drop.paul-moore.com/90.kUgq
> > >
> > > There are currently two tests: 'iouring.2' and 'iouring.3';
> > > 'iouring.1' was lost in a misguided and overzealous 'rm' command.
> > > The first test is standalone and basically tests the SQPOLL
> > > functionality while the second tests sharing io_urings across process
> > > boundaries and the credential/personality sharing mechanism. The
> > > console output of both tests isn't particularly useful, the more
> > > interesting bits are in the audit and LSM specific logs. The
> > > 'iouring.2' command requires no special arguments to run but the
> > > 'iouring.3' test is split into a "server" and "client"; the server
> > > should be run without argument:
> > >
> > > % ./iouring.3s
> > > >>> server started, pid = 11678
> > > >>> memfd created, fd = 3
> > > >>> io_uring created; fd = 5, creds = 1
> > >
> > > ... while the client should be run with two arguments: the first is
> > > the PID of the server process, the second is the "memfd" fd number:
> > >
> > > % ./iouring.3c 11678 3
> > > >>> client started, server_pid = 11678 server_memfd = 3
> > > >>> io_urings = 5 (server) / 5 (client)
> > > >>> io_uring ops using creds = 1
> > > >>> async op result: 36
> > > >>> async op result: 36
> > > >>> async op result: 36
> > > >>> async op result: 36
> > > >>> START file contents
> > > What is this life if, full of care,
> > > we have no time to stand and stare.
> > > >>> END file contents
> > >
> > > The tests were hacked together from various sources online,
> > > attribution and links to additional info can be found in the test
> > > sources, but I expect these tests to die a fiery death in the not
> > > to distant future as I work to add some proper tests to the SELinux
> > > and audit test suites.
> > >
> > > As I believe these patches should spend a full -rcX cycle in
> > > linux-next, my current plan is to continue to solicit feedback on
> > > these patches while they undergo additional testing (next up is
> > > verification of the audit filter code for io_uring). Assuming no
> > > critical issues are found on the mailing lists or during testing, I
> > > will post a proper patchset later with the idea of merging it into
> > > selinux/next after the upcoming merge window closes.
> > >
> > > Any comments, feedback, etc. are welcome.
> >
> > Thanks for the tests. I have a bunch of userspace patches to add to the
> > last set I posted and these tests will help exercise them. I also have
> > one more kernel patch to post... I'll dive back into that now. I had
> > wanted to post them before now but got distracted with AUDIT_TRIM
> > breakage.
>
> Please tell me about liburing.h that is needed for these. There is one
> in tools/io_uring/liburing.h but I don't think that one is right.
>
> The next obvious one would be include/uapi/linux/io_uring.h
>
> I must be missing something obvious here...

You are looking for the liburing header files, the upstream is here:
-> https://github.com/axboe/liburing

If you are on a RH/IBM based distro it is likely called liburing[-devel]:

% dnf whatprovides */liburing.h
Last metadata expiration check: 0:38:37 ago on Wed 25 Aug 2021 08:54:22 PM EDT.
liburing-devel-2.0-2.fc35.i686 : Development files for Linux-native io_uring I/O
: access library
Repo : rawhide
Matched from:
Filename : /usr/include/liburing.h

liburing-devel-2.0-2.fc35.x86_64 : Development files for Linux-native io_uring
: I/O access library
Repo : @System
Matched from:
Filename : /usr/include/liburing.h

liburing-devel-2.0-2.fc35.x86_64 : Development files for Linux-native io_uring
: I/O access library
Repo : rawhide
Matched from:
Filename : /usr/include/liburing.h

--
paul moore