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ssh: expose negotiated algorithms

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Fixes golang/go#58523
Fixes golang/go#46638

Change-Id: Ic64bd2fdd6e9ec96acac3ed4be842e2fbb15231d
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/538235
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Auto-Submit: Nicola Murino <nicola.murino@gmail.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Nicola Murino
2025-05-15 10:44:04 -07:00
committed by Gopher Robot
parent 78a1fd7893
commit e944286e33
10 changed files with 139 additions and 64 deletions
Download Patch File Download Diff File Expand all files Collapse all files
ssh/common.go
+20 -18
View File
@@ -236,6 +236,14 @@ var (
}
)
// NegotiatedAlgorithms defines algorithms negotiated between client and server.
type NegotiatedAlgorithms struct {
KeyExchange string
HostKey string
Read DirectionAlgorithms
Write DirectionAlgorithms
}
// Algorithms defines a set of algorithms that can be configured in the client
// or server config for negotiation during a handshake.
type Algorithms struct {
@@ -346,15 +354,16 @@ func findCommon(what string, client []string, server []string) (common string, e
return "", fmt.Errorf("ssh: no common algorithm for %s; client offered: %v, server offered: %v", what, client, server)
}
// directionAlgorithms records algorithm choices in one direction (either read or write)
type directionAlgorithms struct {
// DirectionAlgorithms defines the algorithms negotiated in one direction
// (either read or write).
type DirectionAlgorithms struct {
Cipher string
MAC string
Compression string
compression string
}
// rekeyBytes returns a rekeying intervals in bytes.
func (a *directionAlgorithms) rekeyBytes() int64 {
func (a *DirectionAlgorithms) rekeyBytes() int64 {
// According to RFC 4344 block ciphers should rekey after
// 2^(BLOCKSIZE/4) blocks. For all AES flavors BLOCKSIZE is
// 128.
@@ -374,27 +383,20 @@ var aeadCiphers = map[string]bool{
CipherChaCha20Poly1305: true,
}
type algorithms struct {
kex string
hostKey string
w directionAlgorithms
r directionAlgorithms
}
func findAgreedAlgorithms(isClient bool, clientKexInit, serverKexInit *kexInitMsg) (algs *NegotiatedAlgorithms, err error) {
result := &NegotiatedAlgorithms{}
func findAgreedAlgorithms(isClient bool, clientKexInit, serverKexInit *kexInitMsg) (algs *algorithms, err error) {
result := &algorithms{}
result.kex, err = findCommon("key exchange", clientKexInit.KexAlgos, serverKexInit.KexAlgos)
result.KeyExchange, err = findCommon("key exchange", clientKexInit.KexAlgos, serverKexInit.KexAlgos)
if err != nil {
return
}
result.hostKey, err = findCommon("host key", clientKexInit.ServerHostKeyAlgos, serverKexInit.ServerHostKeyAlgos)
result.HostKey, err = findCommon("host key", clientKexInit.ServerHostKeyAlgos, serverKexInit.ServerHostKeyAlgos)
if err != nil {
return
}
stoc, ctos := &result.w, &result.r
stoc, ctos := &result.Write, &result.Read
if isClient {
ctos, stoc = stoc, ctos
}
@@ -423,12 +425,12 @@ func findAgreedAlgorithms(isClient bool, clientKexInit, serverKexInit *kexInitMs
}
}
ctos.Compression, err = findCommon("client to server compression", clientKexInit.CompressionClientServer, serverKexInit.CompressionClientServer)
ctos.compression, err = findCommon("client to server compression", clientKexInit.CompressionClientServer, serverKexInit.CompressionClientServer)
if err != nil {
return
}
stoc.Compression, err = findCommon("server to client compression", clientKexInit.CompressionServerClient, serverKexInit.CompressionServerClient)
stoc.compression, err = findCommon("server to client compression", clientKexInit.CompressionServerClient, serverKexInit.CompressionServerClient)
if err != nil {
return
}