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Add cached OCSP client support to Cert Auth #17093

Merged
merged 44 commits into from
Nov 21, 2022
Merged

Add cached OCSP client support to Cert Auth #17093

merged 44 commits into from
Nov 21, 2022

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sgmiller
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@sgmiller sgmiller commented Sep 9, 2022

Using a modified version of an Apache licensed OCSP client for Go, modified
to use Vault's storage and have better more consistent error handling,
support for custom configured CAs and overridden OCSP servers.

Mostly for early consideration.

@sgmiller sgmiller requested a review from a team September 9, 2022 20:08
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A bunch of nits but overall 👍

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sgmiller commented Sep 9, 2022

A bunch of nits but overall +1

Yeah, I expected a lot of nits given the sprint of coding.

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sgmiller commented Sep 9, 2022

A bunch of nits but overall +1

Yeah, I expected a lot of nits given the sprint of coding.

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I've gotta take another look at the trusted cert stuff and make sure I understand that, but this is a first pass review on stuff.

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A few nits on the non-OCSP responder stuff. I think the last one might be a bug.

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Some initial thoughts.

I think two things are worth addressing:

  • The behavior within doRequest in the OCSP client,
  • that nextUpdate is an optional field.

the rest I don't think is critical AFAICT.

}
if len(rest) > 0 {
// extra bytes to the end
return nil, err
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This returns nil, nil, wouldn't we want to return a non-nil error here?


// isInValidityRange checks the validity
func isInValidityRange(currTime, nextUpdate time.Time) bool {
return !nextUpdate.IsZero() && !currTime.After(nextUpdate)
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My reading of https://datatracker.ietf.org/doc/html/rfc6960#section-3.2 seems to state that nextUpdate is an optional field, i.e., if the OCSP responder doesn't know, they can leave this field blank.

This matches the ASN.1:

      nextUpdate         [0]       EXPLICIT GeneralizedTime OPTIONAL,

If that's the case, I'd probably just sub in the default cache expiry period to make things simple, tbh.

case ocsp.Good:
return &ocspStatus{
code: ocspStatusGood,
err: nil,
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Can probably elide err: nil for consistency.

return returnOCSPStatus(ocspRes), nil
}

func returnOCSPStatus(ocspRes *ocsp.Response) *ocspStatus {
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Seems weird that we're translating from one internal form to another internal form?

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Is this possibly for their file caching?

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Yeah, wondering if perhaps it is that. Then they're stable internal identifiers rather than external identifiers that might potentially change and break their cached entries.

But still, I don't think Go upstream would make that type of constants change, except maybe if they import x/ocsp into the main series.

if cacheValue == nil {
return &ocspStatus{
code: ocspMissedCache,
err: fmt.Errorf("miss cache data. subject: %v", subjectName),
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Subject... is just used to have something to log?

producedAt: float64(ocspRes.ProducedAt.UTC().Unix()),
thisUpdate: float64(ocspRes.ThisUpdate.UTC().Unix()),
nextUpdate: float64(ocspRes.NextUpdate.UTC().Unix()),
}
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Don't we need to set status here, out of curiosity?

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I would think so

if !verifiedChains[i][numberOfNoneRootCerts].IsCA || string(verifiedChains[i][numberOfNoneRootCerts].RawIssuer) != string(verifiedChains[i][numberOfNoneRootCerts].RawSubject) {
// Check if the last Non Root Cert is also a CA or is self signed.
// if the last certificate is not, add it to the list
rca := c.caRoot[string(verifiedChains[i][numberOfNoneRootCerts].RawIssuer)]
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Root subjects are not necessarily unique, but we can fix this later I suppose :-)

return nil
}

func (c *Client) ValidateWithCacheForAllCertificates(verifiedChains []*x509.Certificate) (bool, error) {
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Just curious why this is exported?

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Earlier version of the code called this. Fixed.

return true, nil
}

func (c *Client) ValidateWithCache(subject, issuer *x509.Certificate) (*ocspStatus, []byte, *certIDKey, error) {
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As above. :-)

}

// insecureOcspTransport is the transport object that doesn't do certificate revocation check.
func newInsecureOcspTransport(extraCas []*x509.Certificate) *http.Transport {
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Should this just go in the test helpers?

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Now that we have them, yes.

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Actually, no, it is used by the OCSP request logic itself.

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Ah, d'oh, sorry.

I don't like the name then, its not any more insecure than the default Go helper, perhaps just newTransportWithoutOcsp?


// cache key
type certIDKey struct {
HashAlgorithm crypto.Hash
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@cipherboy cipherboy Nov 7, 2022

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Per discussion on Slack, we can probably remove this field and clarify that NameHash is the Issuer's Name (for uniqueness) and the SerialNumber is the leaf's serial number; combination of (IssuerName, IssuerKey) should uniquely identify the issuer, and LeafSerialNumber should uniquely identify the leaf within that parent issuer.

Consensus seems to be that the hash algorithm doesn't matter (as it is whatever the OCSP responder uses and doesn't really change our behavior if we want to prefer other hashes) even if it has changed, doesn't really impact our treating previously cached entries as valid or not, given the other three fields are still unique.

@sgmiller sgmiller requested review from cipherboy and a team November 8, 2022 16:44
@sgmiller sgmiller requested a review from a team November 8, 2022 18:05
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I don't think anything left blocks merging!

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return returnOCSPStatus(ocspRes), nil
}

func returnOCSPStatus(ocspRes *ocsp.Response) *ocspStatus {
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Yeah, wondering if perhaps it is that. Then they're stable internal identifiers rather than external identifiers that might potentially change and break their cached entries.

But still, I don't think Go upstream would make that type of constants change, except maybe if they import x/ocsp into the main series.

@cipherboy cipherboy removed the request for review from a team November 9, 2022 14:43
@sgmiller sgmiller merged commit a611748 into main Nov 21, 2022
@sgmiller sgmiller deleted the cert-auth-ocsp branch November 21, 2022 16:39
@cipherboy cipherboy added this to the 1.13.0 milestone Apr 13, 2023
@celesteking
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Can we please get configurable ocsp request timeouts? Imagine ocsp responder being down (firewalled, incorrectly configured, etc), your ocsp client would be banging it 5 times before giving up. And the cert auth would hang for ~1 min. This isn't the way to do things. Thanks.

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4 participants