[9] RFR 8078661: [SunPKCS11] Fails to cast into RSAPrivateCrtKey after RSA KeyPair Generation
Valerie Peng
valerie.peng at oracle.com
Thu Aug 18 20:49:22 UTC 2016
Hi Mike,
Thanks for the feedback and the detailed write up.
The scenario here is complicated by the sensitive/non-extractable keys
of PKCS#11 and the fact that java key and key specification classes
assume all relevant values being available. Only when all relevant
values are available, then we will construct the corresponding key
objects. This is necessary as there are other providers which may
receive such keys and they can't handle keys like this.
I am sure that the current PKCS11 provider code needs many
improvement/finer handlings. But I don't see a straightforward way of
"making CKA_PUBLIC_EXPONENT available" across various RSA Key classes.
This should be tracked in a different issue.
Given the current release schedule, the deadline for this fix (P4) is
coming up in 10 days and I will be on vacation next week.
If you agree with the value of addressing this with the proposed changes
for JDK 9, then we can proceed.
Otherwise, I will defer this bug to the update release and we can spend
more time to polish this.
Valerie
On 8/18/2016 8:40 AM, Michael StJohns wrote:
> On 8/17/2016 11:36 PM, Valerie Peng wrote:
>> Regression tests are still running, but thought that I will send the
>> updated webrev out and see if there are more comments.
>>
>> Webrev is updated at:
>> http://cr.openjdk.java.net/~valeriep/8078661/webrev.01/
>>
>> Thanks,
>> Valerie
> Hi Valerie -
>
> You know - re-reading this code I'm reminding of why PKCS11 annoys me
> so much.
>
> At line 333 (of the "new" P11Key) you grab the Token, Sensitive and
> Extractable values and if the private data is sensitive or not
> extractable you create a generic P11PrivateKey and return that.
> However the contract for RSAKey requires that the public modulus be
> returned if available, and, since its not a sensitive attribute it
> probably should be available. Also, even if the key is sensitive - if
> its a sensitive CRT key, then CKA_PUBLIC_EXPONENT should be available.
>
> That's going to be a surprise if someone tries to cast this return to
> an (RSAKey) or (RSAPrivateKey). _This should be changed so a key of
> the appropriate type is always created._
>
> Also, checking for CKA_EXTRACTABLE being true, doesn't actually get
> you access to the clear text information. If a key is extractable,
> then it can be wrapped out under another key. The components
> themselves aren't available. It's possible to have a non-sensitive,
> non-extractable key where the components are retrievable, but the key
> can't be wrapped out.
>
>
> (Hmm... the public exponent is in RSAPublicKey and RSAPrivateCRTKey,
> but should probably be in RSAKey instead).
>
> So:
>
> All RSA keys - even the sensitive private ones - should return
> CKA_MODULUS.
> All RSA Private CRT Keys - even the sensitive ones - should also
> return CKA_PUBLIC_EXPONENT.
> All non-sensitive RSA Private keys - should also return
> CKA_PRIVATE_EXPONENT
> All non-sensitive RSA Private CRT Keys - should also return
> CKA_PRIME_1, CKA_PRIME_2, CKA_EXPONENT_1, CKA_EXPONENT_2 and
> CKA_COEFFICIENT.
>
> This is harder to do than it needs to be due to how
> p11_objmgt.c::Java_sun_security_pkcs11_wrapper_PKCS11_C_1GetAttributeValue
> is built. At lines 248 and 270, it does a check for an error return
> and throws an exception if any error occurs. However, for
> C_GetAttributeValue, there are a number of "non-fatal" errors that
> indicate either buffer size errors or sensitivity of one or more
> components or unavailability of one or more components.
>> Note that the error codes CKR_ATTRIBUTE_SENSITIVE,
>> CKR_ATTRIBUTE_TYPE_INVALID, and CKR_BUFFER_TOO_SMALL do not denote
>> true errors for *C_GetAttributeValue*. If a call to
>> *C_GetAttributeValue* returns any of these three values, then the
>> call must nonetheless have processed /every/ attribute in the
>> template supplied to *C_GetAttributeValue*. Each attribute in the
>> template whose value /can be/ returned by the call to
>> *C_GetAttributeValue* /will be/ returned by the call to
>> *C_GetAttributeValue*.
>
>
>
> If you updated this slightly - maybe by adding a new method to
> wrapper.PKCS11 (say GetAttributeValuesNoError) - to return the
> attributes it was able to get in the call with nulls elsewhere, then
> you could do all of the above in one pass.
>
> Sorry to complicate this. Mike
>
> ps - I don't have a current build environment set up for the JDK,
> otherwise I'd code it and test it myself. I'm happy to take a swing
> at it and provide you unverified code you can integrate.
>
>>
>> On 8/17/2016 9:55 AM, Michael StJohns wrote:
>>> On 8/16/2016 9:24 PM, Valerie Peng wrote:
>>>>
>>>> Anyone has time to review a straightforward fix? The current PKCS11
>>>> code assume that if public exponent is available for RSA Private
>>>> Key, then it's a RSA CRT key. However, not all vendor
>>>> implementation works this way. Changing to a tighter check and did
>>>> minor code-refactoring to avoid re-retrieving the attribute values.
>>>>
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8078661
>>>> Webrev: http://cr.openjdk.java.net/~valeriep/8078661/webrev.00/
>>>>
>>>> Thanks,
>>>> Valerie
>>>
>>> Given that there's a change to PKCS11 for 2.40 that says that all
>>> RSA private key objects MUST also store CKA_PUBLIC_EXPONENT, some
>>> change needed to be made.
>>>
>>> Sorry - I don't think this fix will work. Or if its working on your
>>> version of PKCS11, your version of PKCS11 is doing it wrong. The
>>> problem is that if you specify attributes that don't exist on the
>>> object, the underlying PKCS11 library is supposed to return
>>> CKR_ATTRIBUTE_TYPE_INVALID. And that should trigger a thrown
>>> exception before you ever get anything copied to your attributes.
>>>
>>> 1) Get modulus and private exponent first. That gives you the stuff
>>> for a generic RSA private key - and if it fails, there's no reason
>>> to continue.
>>>
>>> 2) Then get the rest of the stuff. If that fails, then you already
>>> have the stuff you need for a normal private key.
>>>
>>>
>>>> boolean crtKey;
>>>> try {
>>>> session.token.p11.C_GetAttributeValue
>>>> (session.id(), keyID, attrs2);
>>>> - crtKey = (attrs2[0].pValue instanceof byte[]);
>>>> + crtKey = ((attrs2[1].pValue instanceof byte[]) &&
>>>> + (attrs2[3].pValue instanceof byte[]) &&
>>>> + (attrs2[4].pValue instanceof byte[]) &&
>>>> + (attrs2[5].pValue instanceof byte[]) &&
>>>> + (attrs2[6].pValue instanceof byte[]) &&
>>>> + (attrs2[7].pValue instanceof byte[])) ;
>>>> } catch (PKCS11Exception e) {
>>>> // ignore, assume not available
>>>> crtKey = false;
>>>> }
>>>
>>> // Change attrs2 so it only has the additional CRT attributes (e.g.
>>> delete CKA_MODULUS, CKA_PRIVATE_EXPONENT from the list
>>>
>>> Replace the above with
>>>
>>> CK_ATTRIBUTE[] attrs3 = new CK_ATTRIBUTE[] {
>>> new CK_ATTRIBUTE(CKA_MODULUS),
>>> new CK_ATTRIBUTE(CKA_PRIVATE_EXPONENT)
>>> };
>>> // no try block needed here - we want to throw the error if it occurs
>>> session.token.p11.C_GetAttributeValue (session.id(), keyID, attrs3);
>>>
>>> // So far so good - we have the base attributes, let's see if we can
>>> get the additional attributes;
>>>
>>> try {
>>> session.token.p11.C_GetAttributeValue(session.id(),keyID, attrs2);
>>> } catch (PKCS11Exception e) {
>>> // we really should check the return value for one of the
>>> non-fatal values, but let's just assume its not a CRT key
>>> return new P11RSAPrivateNonCRTKey (session, keyID, algorithm,
>>> keyLength, attrs2, attrs3);
>>> }
>>>
>>> // if we fall through then its a CRT key
>>> // -- we should check for byte[] ness of each of the components, and
>>> throw an error if they arent - but which error?
>>>
>>> return new P11RSAPrivateKey (session, keyID, algorithm, keyLength,
>>> attrs2, attrs3);
>>>
>>> // there are cleanups necessary in other places. I'd suggest rather
>>> than depending on the ordering of attributes, you do assignment by
>>> CKA_ values just so someone coming later doesn't mess things up by
>>> mistake. Also, a hell of a lot more readable.
>>>
>>> static CK_ATTRIBUTE getAttribute (CK_ATTRIBUTE[] attrs, long attrType) {
>>> for (CK_ATTRIBUTE a : attrs) {
>>> if (a.type == attrType)
>>> return a;
>>> }
>>> return null; // or throw something?
>>> }
>>>
>>>
>>> coeff = getAtttribute(attrs,CKA_COEFFICIENT).getBigInteger();
>>>
>>>
>>> The other possibility is to change the C code for
>>> C_GetAttributeValues so it doesn't error out for the non-fatal error
>>> codes and instead returns a null value attribute when the attribute
>>> is missing.
>>>
>>> Mike
>>>
>>
>
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