crypto/x509: RevocationList.CheckSignatureFrom doesn't check Subject

[thierry-f-78]

What version of Go are you using (go version)?

$ go version
go version go1.20.5 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/thierry/Library/Caches/go-build"
GOENV="/Users/thierry/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/thierry/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/thierry/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.20.5"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/thierry/git/XXX/poc/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/_d/zs7l5ldx1r94fn_qh1zvn1rw0000gn/T/go-build3292834562=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I try to validate CRL files. I use three CA certificate:

• The first one (ca.pem) is the legit certificate which sign the CRL
• The second one (ca_very_wrong.pem) is wrong certificate with any key
• The third one (ca_wrong.pem) is not the right CA certificate but it have the same private key than (ca.pem)

With openssl I observe this behaviour:

$ openssl crl -in ca.crl -CAfile ca.pem -noout
verify OK

$ openssl crl -in ca.crl -CAfile ca_very_wrong.pem -noout
Error getting CRL issuer certificate

$ openssl crl -in ca.crl -CAfile ca_wrong.pem -noout
Error getting CRL issuer certificate

It's the expected behaviour.

With Golang primitives, the last case is true. This behaviour is wrong.

I join zip file with a poc.

What did you expect to see?

I Expect the function CheckSignatureFrom() with certificate ca_wrong.pem return an error

What did you see instead?

Function CheckSignatureFrom() with certificate ca_wrong.pem end with success

poc.zip

[seankhliao]

my reading of RFC 5820 Seection 6.3.3 step g
makes me think that matching the other certificate contents isn't necessary, only that the public key matches.

cc @golang/security

[thierry-f-78]

You're right !

If I understand right the issuer must be checked at the b.1 step according with the distribution point. In my case, I got CRL and CA from configuration, not from certificate, so I understand that i do check the issuer control myself.

so, anyway it's a marginal case !

Note, I'm not familiar with crypto and certificate, but it seems the f step which verify certification chain implies control of the ISSUER. (it is the case for certificates, the function isValid verify issuer - https://cs.opensource.google/go/go/+/refs/tags/go1.20.5:src/crypto/x509/verify.go;drc=36b87f273cc43e21685179dc1664ebb5493d26ae;l=565)