Messages in this thread | | | Date | Wed, 13 Feb 2013 19:33:13 +0200 | Subject | Re: [PATCH 2/2] ima: Support appraise_type=imasig_optional | From | "Kasatkin, Dmitry" <> |
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On Wed, Feb 13, 2013 at 3:44 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote: > On Wed, 2013-02-13 at 15:13 +0200, Kasatkin, Dmitry wrote: >> On Wed, Feb 13, 2013 at 2:56 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote: >> > On Wed, 2013-02-13 at 14:31 +0200, Kasatkin, Dmitry wrote: >> >> On Mon, Feb 11, 2013 at 10:11 PM, Vivek Goyal <vgoyal@redhat.com> wrote: >> > >> >> > @@ -158,7 +165,8 @@ int ima_appraise_measurement(int func, struct integrity_iint_cache *iint, >> >> > } >> >> > switch (xattr_value->type) { >> >> > case IMA_XATTR_DIGEST: >> >> > - if (iint->flags & IMA_DIGSIG_REQUIRED) { >> >> > + if (iint->flags & IMA_DIGSIG_REQUIRED || >> >> > + iint->flags & IMA_DIGSIG_OPTIONAL) { >> >> > cause = "IMA signature required"; >> >> > status = INTEGRITY_FAIL; >> >> > break; >> >> >> >> This looks a bit odd... If "optional" signature is missing - we fail.. >> >> It is optional... Why we should fail? >> > >> > 'imasig_optional' does not only mean that the signature is optional, but >> > also implies that it has to be a digital signature, not a hash. This >> > latter part is what IMA_DIGSIG_REQUIRED means. >> > >> > If 'imasig_optional' set both 'IMA_DIGSIG_OPTIONAL' and >> > 'IMA_DIGSIG_REQUIRED', then this change wouldn't be necessary. >> > >> > IMA_DIGSIG_REQUIRED would enforce that it is a signature. >> > IMA_DIGSIG_OPTIONAL would fail only for files with invalid signatures. >> > >> >> It sounds odd that optional signature is actually required. >> Optional for me means that it may be there or may be not. >> If it is not there, then it may be hash or nothing. >> >> I see it is more logical if it is "appraise_type=optional", >> which means that we might have no xattr value, hash or signature. >> It if happens to be a signature, then IMA_DIGSIG flag will be set. > > Right, 'appraise_type=' could have been defined either as a comma > separated list of options (eg. appraise_type=imassig,optional) or, as > Vivek implemented, a new option. Eventually, we will need to extend > 'appraise_type=' (eg. required algorithm), but for now I don't have a > problem with the new option. >
It is not exactly what I meant. IOW, I do not want appraise_type=imasig,optional.
Optional for me is that xattr value is optional. It might be nothing, hash or imasig...
If it would happen that it contains signature, then IMA_DIGSIG flag would be set, and process could get needed capability as Vivek wants.
- Dmitry
> thanks, > > Mimi > >> I asked Vivek to send a policy file he uses in his system. >> I would like to see how system configured as a whole... >> >> - Dmitry > >
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