Re: [PATCH 2/2] test/py: efi_secboot: adjust secure boot tests to code changes

Ilias Apalodimas
2022-02-15T06:50:20Z

Akashi-san,

> > > > > >
> > > > > > + # Try rejection in reverse order.
> > > > >
> > > > > "Reverse order" of what?
> > > >
> > > > Of the test right above
> > >
> > > Please specify the signature database, I guess "dbx"?
> > >
> > > > >
> > > > > > + u_boot_console.restart_uboot()
> > > > >
> > > > > I don't think we need 'restart' here.
> > > > > I added it in each test function (not test case), IIRC, because we didn't
> > > > > have file-based non-volatile variables at that time.
> > > >
> > > > You do. dbx already holds dbx_hash.auth and dbx1_hash.auth (in that order) at
> > > > that point. The point is cleaning up dbx and testing against dbx1_hash.
> > >
> > > Why not simply overwrite "dbx" variable?
> > > Without "-a", "env set -e" does it if it is properly signed with KEK.
> > >
> >
> > I am not sure you've understood the bug yet. If I did that, db's 1sts
> > entry would still be there. The whole point is insert dbx1_hash first.
>
> I think that I understand your intension.
>
> You meant "db's 1st entry" -> "dbx's 1st entry" in above sentence.
> Right?

Yes

>
> # That is why, in my previous comment, I asked you to specify the test case
> number and the signature database's name explicitly in a comment to avoid any
> ambiguity.

Ok. I was planning on updating some more tests, so I'll try to spit that
up there as well.

>
> When you said "in a reversed order" in your commit, I expected that either
> 1.the image(helloworld.efi) has two signatures in a reversed order, or
> (You hinted this possibility in our chat yesterday.)
> 2."db" has "db1.auth" and "db.auth" in this order, or
> 3."dbx" has "dbx_hash1.auth" and "dbx_hash.auth" in this order
> in this context, but your change didn't do neither.
>
> You intended (3). Right?

Yes, however inserting dbx_hash.auth right after dbx_hash1.auth didnt work
for me. There's something date related which prevents us from adding both
of the sha256 hashes of the certs in reverse order. However I think that
inserting dbx_hash1.auth is enough for the test purpose. The whole point
was to verify the change of the first patch, were a binary gets rejected on
ony dbx match.

>
> > The
> > easiest way to do this is on an empty database, instead of starting
> > overwriting and cleaning variables. Why is rebooting even a problem?
>
> If "dbx" is a matter, the easiest way is to simply overwrite that variable.
> (Apparently we don't need any cleanup.)
>

Ah sure, I can test that and send a patch along with some more test cases I
got in mind.

> >
> > > > >
> > > > > > + with u_boot_console.log.section('Test Case 5e'):
> > > > > > + # Test Case 5e, authenticated even if only one of signatures
> > > > > > + # is verified. Same as before but reject dbx_hash1.auth only
> > > > >
> > > > > Please specify what test case "before" means.
> > > >
> > > > The test that run right before that
> > >
> > > Please add a particular test case number to avoid any ambiguity.
> > > I believe that a test case description should be easy enough to understand
> > > and convey no ambiguity especially if there is some subtle difference
> > > between cases.
> >
> > This is exactly the test case right above with dbx1_auth inserted first. I
> > think it's fine under the current test.
>
> See my comment above.
>
> >
> > >
> > > > >
> > > > > > + output = u_boot_console.run_command_list([
> > > > > > + 'host bind 0 %s' % disk_img,
> > > > > > + 'fatload host 0:1 4000000 db.auth',
> > > > > > + 'setenv -e -nv -bs -rt -at -i 4000000:$filesize db',
> > > > > > + 'fatload host 0:1 4000000 KEK.auth',
> > > > > > + 'setenv -e -nv -bs -rt -at -i 4000000:$filesize KEK',
> > > > > > + 'fatload host 0:1 4000000 PK.auth',
> > > > > > + 'setenv -e -nv -bs -rt -at -i 4000000:$filesize PK',
> > > > > > + 'fatload host 0:1 4000000 db1.auth',
> > > > > > + 'setenv -e -nv -bs -rt -at -a -i 4000000:$filesize db',
> > > > > > + 'fatload host 0:1 4000000 dbx_hash1.auth',
> > > > > > + 'setenv -e -nv -bs -rt -at -i 4000000:$filesize dbx'])
> > > > >
> > > > > Now "db" has db.auth and db1.auth in this order and
> > > > > 'dbx" has dbx_hash1.auth.
> > > > > Is this what you intend to test?
> > > >
> > > > Yes. The patchset solved 2 bugs. One was not rejecting the image when a
> > > > single dbx entry was found. The second was that depending on the order the
> > > > image was signed and the keys inserted into dbx, the code could reject or
> > > > accept the image.
> > >
> > > Which part of "dbx" (or "db"?) is in a reverse order?
> >
> > the first tests add dbx_hash -> dbx1_hash, while the second purges the dbx
> > database and adds dbx1_hash to test against.
>
> See my comment above.
>
> -Takahiro Akashi
>
> > Regards
> > /Ilias
> > >
> > > -Takahiro Akashi
> > >
> > >
> > > > >
> > > > > -Takahiro Akashi
> > > > >
> > > > > > + assert 'Failed to set EFI variable' not in ''.join(output)
> > > > > > + output = u_boot_console.run_command_list([
> > > > > > + 'efidebug boot add -b 1 HELLO host 0:1 /helloworld.efi.signed_2sigs -s ""',
> > > > > > + 'efidebug boot next 1',
> > > > > > + 'efidebug test bootmgr'])
> > > > > > + assert '\'HELLO\' failed' in ''.join(output)
> > > > > > + assert 'efi_start_image() returned: 26' in ''.join(output)
> > > > > > +
> > > > > > def test_efi_signed_image_auth6(self, u_boot_console, efi_boot_env):
> > > > > > """
> > > > > > Test Case 6 - using digest of signed image in database
> > > > > > --
> > > > > > 2.32.0
> > > > > >
> > > >
> > > > Regards
> > > > /Ilias