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ssh: add MultiAlgorithmSigner

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MultiAlgorithmSigner allows to restrict client-side, server-side and
certificate signing algorithms.

Fixes golang/go#52132
Fixes golang/go#36261

Change-Id: I295092f1bba647327aaaf294f110e9157d294159
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/508398
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Nicola Murino
2023-09-20 18:10:30 +00:00
committed by Gopher Robot
parent 3f0842a464
commit 28c53ff63c
9 changed files with 554 additions and 66 deletions
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ssh/handshake.go
+23 -11
View File
@@ -461,19 +461,24 @@ func (t *handshakeTransport) sendKexInit() error {
isServer := len(t.hostKeys) > 0
if isServer {
for _, k := range t.hostKeys {
// If k is an AlgorithmSigner, presume it supports all signature algorithms
// associated with the key format. (Ideally AlgorithmSigner would have a
// method to advertise supported algorithms, but it doesn't. This means that
// adding support for a new algorithm is a breaking change, as we will
// immediately negotiate it even if existing implementations don't support
// it. If that ever happens, we'll have to figure something out.)
// If k is not an AlgorithmSigner, we can only assume it only supports the
// algorithms that matches the key format. (This means that Sign can't pick
// a different default.)
// If k is a MultiAlgorithmSigner, we restrict the signature
// algorithms. If k is a AlgorithmSigner, presume it supports all
// signature algorithms associated with the key format. If k is not
// an AlgorithmSigner, we can only assume it only supports the
// algorithms that matches the key format. (This means that Sign
// can't pick a different default).
keyFormat := k.PublicKey().Type()
if _, ok := k.(AlgorithmSigner); ok {
switch s := k.(type) {
case MultiAlgorithmSigner:
for _, algo := range algorithmsForKeyFormat(keyFormat) {
if contains(s.Algorithms(), underlyingAlgo(algo)) {
msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, algo)
}
}
case AlgorithmSigner:
msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, algorithmsForKeyFormat(keyFormat)...)
} else {
default:
msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, keyFormat)
}
}
@@ -685,9 +690,16 @@ func (a algorithmSignerWrapper) SignWithAlgorithm(rand io.Reader, data []byte, a
func pickHostKey(hostKeys []Signer, algo string) AlgorithmSigner {
for _, k := range hostKeys {
if s, ok := k.(MultiAlgorithmSigner); ok {
if !contains(s.Algorithms(), underlyingAlgo(algo)) {
continue
}
}
if algo == k.PublicKey().Type() {
return algorithmSignerWrapper{k}
}
k, ok := k.(AlgorithmSigner)
if !ok {
continue