Re: [PATCH 2/2] keys, trusted: seal with a policy

[Mimi Zohar]

On Wed, 2015-12-09 at 16:24 +0200, Jarkko Sakkinen wrote:
> On Tue, Dec 08, 2015 at 06:56:17PM -0500, Mimi Zohar wrote:
> > On Tue, 2015-12-08 at 22:24 +0200, Jarkko Sakkinen wrote:
> > > On Tue, Dec 08, 2015 at 01:01:02PM +0200, Jarkko Sakkinen wrote:
> > > > On Tue, Dec 08, 2015 at 09:35:05AM +1100, James Morris wrote:
> > > > > On Mon, 7 Dec 2015, Jarkko Sakkinen wrote:
> > > > > 
> > > > > > On Fri, Nov 20, 2015 at 01:34:35PM +1100, James Morris wrote:
> > > > > > > On Wed, 18 Nov 2015, Jarkko Sakkinen wrote:
> > > > > > > 
> > > > > > > > On Wed, Nov 18, 2015 at 11:21:01AM +1100, James Morris wrote:
> > > > > > > > > On Tue, 17 Nov 2015, Jarkko Sakkinen wrote:
> > > > > > > > > 
> > > > > > > > > > }
> > > > > > > > > > break;
> > > > > > > > > > +   case Opt_policydigest:
> > > > > > > > > > +   if (!tpm2 ||
> > > > > > > > > > +   strlen(args[0].from) != (2 * 
> > > > > > > > > > opt->digest_len))
> > > > > > > > > > +   return -EINVAL;
> > > > > > > > > > +   kfree(opt->policydigest);
> > > > > > > > > > +   opt->policydigest = 
> > > > > > > > > > kzalloc(opt->digest_len,
> > > > > > > > > > +   GFP_KERNEL);
> > 
> > You're allocating the exact amount of storage needed.  There's no reason
> > to use kzalloc here or elsewhere in the patch.
> 
> Yup. I'll change this.
> 
> > > > > > > > > 
> > > > > > > > > Is it correct to kfree opt->policydigest here before 
> > > > > > > > > allocating it?
> > > > > > > > 
> > > > > > > > I think so. The same option might be encountered multiple times.
> > > > > > > 
> > > > > > > This would surely signify an error?
> > > > > > 
> > > > > > I'm following the semantics of other options. That's why I 
> > > > > > implemented
> > > > > > it that way for example:
> > > > > > 
> > > > > > keyctl add trusted kmk "new 32 keyhandle=0x8000 
> > > > > > keyhandle=0x8000"
> > > > > > 
> > > > > > is perfectly OK. I just thought that it'd be more odd if this option
> > > > > > behaved in a different way...
> > > > > 
> > > > > It seems broken to me -- if you're messing up keyctl commands you 
> > > > > might 
> > > > > want to know about it, but we should remain consistent.
> > > > 
> > > > So should I return error if policyhandle/digest appears a second time? I
> > > > agree that it'd be better to return -EINVAL.
> > > > 
> > > > The existing behavior is such that any option can appear multiple times
> > > > and I chose to be consistent with that.
> > > 
> > > Mimi, David?
> > 
> > I don't have a problem with changing the existing behavior to allow the
> > options to be specified only once.
> 
> I don't think this patch is right place to change the behavior as it
> should be done for other options too.

I think the easiest way of checking if a token has already been seen
would be to define
 a flag and use test_and_set_bit(token, ) after the following code
snippet.

  while ((p = strsep(, " \t"))) {
if (*p == '\0' || *p == ' ' || *p == '\t')
continue;
token = match_token(p, key_tokens, args);

Having a separate patch is probably a good idea.

Mimi

--
To unsubscribe from this list: send the line "unsubscribe 
linux-security-module" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/2] keys, trusted: seal with a policy

[Jarkko Sakkinen]

On Fri, Nov 20, 2015 at 01:34:35PM +1100, James Morris wrote:
> On Wed, 18 Nov 2015, Jarkko Sakkinen wrote:
> 
> > On Wed, Nov 18, 2015 at 11:21:01AM +1100, James Morris wrote:
> > > On Tue, 17 Nov 2015, Jarkko Sakkinen wrote:
> > > 
> > > > }
> > > > break;
> > > > +   case Opt_policydigest:
> > > > +   if (!tpm2 ||
> > > > +   strlen(args[0].from) != (2 * 
> > > > opt->digest_len))
> > > > +   return -EINVAL;
> > > > +   kfree(opt->policydigest);
> > > > +   opt->policydigest = kzalloc(opt->digest_len,
> > > > +   GFP_KERNEL);
> > > 
> > > Is it correct to kfree opt->policydigest here before allocating it?
> > 
> > I think so. The same option might be encountered multiple times.
> 
> This would surely signify an error?

I'm following the semantics of other options. That's why I implemented
it that way for example:

keyctl add trusted kmk "new 32 keyhandle=0x8000 keyhandle=0x8000"

is perfectly OK. I just thought that it'd be more odd if this option
behaved in a different way...

> -- 
> James Morris
> 

/Jarkko
--
To unsubscribe from this list: send the line "unsubscribe 
linux-security-module" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/2] keys, trusted: seal with a policy

[James Morris]

On Mon, 7 Dec 2015, Jarkko Sakkinen wrote:

> On Fri, Nov 20, 2015 at 01:34:35PM +1100, James Morris wrote:
> > On Wed, 18 Nov 2015, Jarkko Sakkinen wrote:
> > 
> > > On Wed, Nov 18, 2015 at 11:21:01AM +1100, James Morris wrote:
> > > > On Tue, 17 Nov 2015, Jarkko Sakkinen wrote:
> > > > 
> > > > >   }
> > > > >   break;
> > > > > + case Opt_policydigest:
> > > > > + if (!tpm2 ||
> > > > > + strlen(args[0].from) != (2 * 
> > > > > opt->digest_len))
> > > > > + return -EINVAL;
> > > > > + kfree(opt->policydigest);
> > > > > + opt->policydigest = kzalloc(opt->digest_len,
> > > > > + GFP_KERNEL);
> > > > 
> > > > Is it correct to kfree opt->policydigest here before allocating it?
> > > 
> > > I think so. The same option might be encountered multiple times.
> > 
> > This would surely signify an error?
> 
> I'm following the semantics of other options. That's why I implemented
> it that way for example:
> 
> keyctl add trusted kmk "new 32 keyhandle=0x8000 keyhandle=0x8000"
> 
> is perfectly OK. I just thought that it'd be more odd if this option
> behaved in a different way...

It seems broken to me -- if you're messing up keyctl commands you might 
want to know about it, but we should remain consistent.


-- 
James Morris


--
To unsubscribe from this list: send the line "unsubscribe 
linux-security-module" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/2] keys, trusted: seal with a policy

[Jarkko Sakkinen]

On Tue, Nov 17, 2015 at 06:27:22PM +0200, Jarkko Sakkinen wrote:
> Support for sealing with a authorization policy.
> 
> Two new options for trusted keys:
> 
> * 'policydigest=': provide an auth policy digest for sealing.
> * 'policyhandle=': provide a policy session handle for unsealing.

I think it is good to say a word about how to test this since the user
space supports is still lagging a bit (there's no way to do a "sticky"
handle in TSS2 yet).

I have my own low-level test scripts over here:

https://github.com/jsakkine/tpm2-scripts

Trivial example:

KEYHANDLE=$(sudo ./tpm2-root-key)
POLICYDIGEST=$(sudo ./tpm2-pcr-policy --pcr 16 --name-alg=sha256 --bank=sha1 
--trial)
POLICYHANDLE=$(sudo ./tpm2-pcr-policy --pcr 16 --name-alg=sha256 --bank=sha1)

KEYID=$(keyctl add trusted kmk "new 32 keyhandle=$KEYHANDLE hash=sha256 
policydigest=$POLICYDIGEST" @u)
keyctl pipe $KEYID
keyctl clear @u
keyctl add trusted kmk "load `cat blob.hex` keyhandle=$KEYHANDLE  
policyhandle=0x0300" @u
keyctl clear @u

sudo ./tpm2-flush $KEYHANDLE

/Jarkko
--
To unsubscribe from this list: send the line "unsubscribe 
linux-security-module" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/2] keys, trusted: seal with a policy

[James Morris]

On Wed, 18 Nov 2015, Jarkko Sakkinen wrote:

> On Wed, Nov 18, 2015 at 11:21:01AM +1100, James Morris wrote:
> > On Tue, 17 Nov 2015, Jarkko Sakkinen wrote:
> > 
> > >   }
> > >   break;
> > > + case Opt_policydigest:
> > > + if (!tpm2 ||
> > > + strlen(args[0].from) != (2 * opt->digest_len))
> > > + return -EINVAL;
> > > + kfree(opt->policydigest);
> > > + opt->policydigest = kzalloc(opt->digest_len,
> > > + GFP_KERNEL);
> > 
> > Is it correct to kfree opt->policydigest here before allocating it?
> 
> I think so. The same option might be encountered multiple times.

This would surely signify an error?


-- 
James Morris


--
To unsubscribe from this list: send the line "unsubscribe 
linux-security-module" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html