crypto/x509: don't accept a root that already appears in a chain.
Since a root certificate is self-signed, it's a valid child of itself.
If a root certificate appeared both in the pool of intermediates and
roots the verification code could find a chain which included it twice:
first as an intermediate and then as a root. (Existing checks prevented
the code from looping any more.)
This change stops the exact same certificate from appearing twice in a
chain. This simplifies the results in the face of the common
configuration error of a TLS server returning a root certificate.
(This should also stop two different versions of the “same” root
appearing in a chain because the self-signature on one will not validate
for the other.)
Fixes #16800.
Change-Id: I004853baa0eea27b44d47b9b34f96113a92ebac8
Reviewed-on: https://go-review.googlesource.com/32121
Run-TryBot: Adam Langley <agl@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/crypto/x509/verify.go b/src/crypto/x509/verify.go
index aa9e374..6988ad7 100644
--- a/src/crypto/x509/verify.go
+++ b/src/crypto/x509/verify.go
@@ -346,8 +346,16 @@
func (c *Certificate) buildChains(cache map[int][][]*Certificate, currentChain []*Certificate, opts *VerifyOptions) (chains [][]*Certificate, err error) {
possibleRoots, failedRoot, rootErr := opts.Roots.findVerifiedParents(c)
+nextRoot:
for _, rootNum := range possibleRoots {
root := opts.Roots.certs[rootNum]
+
+ for _, cert := range currentChain {
+ if cert.Equal(root) {
+ continue nextRoot
+ }
+ }
+
err = root.isValid(rootCertificate, currentChain, opts)
if err != nil {
continue
@@ -360,7 +368,7 @@
for _, intermediateNum := range possibleIntermediates {
intermediate := opts.Intermediates.certs[intermediateNum]
for _, cert := range currentChain {
- if cert == intermediate {
+ if cert.Equal(intermediate) {
continue nextIntermediate
}
}
diff --git a/src/crypto/x509/verify_test.go b/src/crypto/x509/verify_test.go
index 3461292..5a7481f 100644
--- a/src/crypto/x509/verify_test.go
+++ b/src/crypto/x509/verify_test.go
@@ -104,10 +104,6 @@
expectedChains: [][]string{
{"Google", "Google Internet Authority", "GeoTrust"},
- // TODO(agl): this is ok, but it would be nice if the
- // chain building didn't visit the same SPKI
- // twice.
- {"Google", "Google Internet Authority", "GeoTrust", "GeoTrust"},
},
// CAPI doesn't build the chain with the duplicated GeoTrust
// entry so the results don't match. Thus we skip this test
@@ -130,12 +126,8 @@
roots: []string{startComRoot},
currentTime: 1302726541,
- // Skip when using systemVerify, since Windows
- // can only return a single chain to us (for now).
- systemSkip: true,
expectedChains: [][]string{
{"dnssec-exp", "StartCom Class 1", "StartCom Certification Authority"},
- {"dnssec-exp", "StartCom Class 1", "StartCom Certification Authority", "StartCom Certification Authority"},
},
},
{
