From eecaba20310483f64e0e4500fa3ac85e23ced18e Mon Sep 17 00:00:00 2001
From: Cum Gun <cumgun@users.noreply.github.com>
Date: Thu, 2 Nov 2017 16:26:41 +0100
Subject: [PATCH] Configurable SSH key exchange algorithm and MAC suite (#2806)
---
conf/app.ini | 6 ++++++
modules/setting/setting.go | 12 ++++++++++++
modules/ssh/ssh.go | 6 ++++--
routers/init.go | 4 ++--
4 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/conf/app.ini b/conf/app.ini
index 491f38164b..07c60ea0a9 100644
--- a/conf/app.ini
+++ b/conf/app.ini
@@ -128,6 +128,12 @@ SSH_ROOT_PATH =
; For built-in SSH server only, choose the ciphers to support for SSH connections,
; for system SSH this setting has no effect
SSH_SERVER_CIPHERS = aes128-ctr, aes192-ctr, aes256-ctr, aes128-gcm@openssh.com, arcfour256, arcfour128
+; For built-in SSH server only, choose the key exchange algorithms to support for SSH connections,
+; for system SSH this setting has no effect
+SSH_SERVER_KEY_EXCHANGES = diffie-hellman-group1-sha1, diffie-hellman-group14-sha1, ecdh-sha2-nistp256, ecdh-sha2-nistp384, ecdh-sha2-nistp521, curve25519-sha256@libssh.org
+; For built-in SSH server only, choose the MACs to support for SSH connections,
+; for system SSH this setting has no effect
+SSH_SERVER_MACS = hmac-sha2-256-etm@openssh.com, hmac-sha2-256, hmac-sha1, hmac-sha1-96
; Directory to create temporary files when test public key using ssh-keygen,
; default is system temporary directory.
SSH_KEY_TEST_PATH =
diff --git a/modules/setting/setting.go b/modules/setting/setting.go
index a1106132df..3b9aff44e2 100644
--- a/modules/setting/setting.go
+++ b/modules/setting/setting.go
@@ -98,6 +98,8 @@ var (
ListenPort int `ini:"SSH_LISTEN_PORT"`
RootPath string `ini:"SSH_ROOT_PATH"`
ServerCiphers []string `ini:"SSH_SERVER_CIPHERS"`
+ ServerKeyExchanges []string `ini:"SSH_SERVER_KEY_EXCHANGES"`
+ ServerMACs []string `ini:"SSH_SERVER_MACS"`
KeyTestPath string `ini:"SSH_KEY_TEST_PATH"`
KeygenPath string `ini:"SSH_KEYGEN_PATH"`
AuthorizedKeysBackup bool `ini:"SSH_AUTHORIZED_KEYS_BACKUP"`
@@ -110,6 +112,8 @@ var (
Domain: "",
Port: 22,
ServerCiphers: []string{"aes128-ctr", "aes192-ctr", "aes256-ctr", "aes128-gcm@openssh.com", "arcfour256", "arcfour128"},
+ ServerKeyExchanges: []string{"diffie-hellman-group1-sha1", "diffie-hellman-group14-sha1", "ecdh-sha2-nistp256", "ecdh-sha2-nistp384", "ecdh-sha2-nistp521", "curve25519-sha256@libssh.org"},
+ ServerMACs: []string{"hmac-sha2-256-etm@openssh.com", "hmac-sha2-256", "hmac-sha1", "hmac-sha1-96"},
KeygenPath: "ssh-keygen",
}
@@ -732,6 +736,14 @@ func NewContext() {
if len(serverCiphers) > 0 {
SSH.ServerCiphers = serverCiphers
}
+ serverKeyExchanges := sec.Key("SSH_SERVER_KEY_EXCHANGES").Strings(",")
+ if len(serverKeyExchanges) > 0 {
+ SSH.ServerKeyExchanges = serverKeyExchanges
+ }
+ serverMACs := sec.Key("SSH_SERVER_MACS").Strings(",")
+ if len(serverMACs) > 0 {
+ SSH.ServerMACs = serverMACs
+ }
SSH.KeyTestPath = os.TempDir()
if err = Cfg.Section("server").MapTo(&SSH); err != nil {
log.Fatal(4, "Failed to map SSH settings: %v", err)
diff --git a/modules/ssh/ssh.go b/modules/ssh/ssh.go
index 62edaf15bc..aea46daad4 100644
--- a/modules/ssh/ssh.go
+++ b/modules/ssh/ssh.go
@@ -151,10 +151,12 @@ func listen(config *ssh.ServerConfig, host string, port int) {
}
// Listen starts a SSH server listens on given port.
-func Listen(host string, port int, ciphers []string) {
+func Listen(host string, port int, ciphers []string, keyExchanges []string, macs []string) {
config := &ssh.ServerConfig{
Config: ssh.Config{
- Ciphers: ciphers,
+ Ciphers: ciphers,
+ KeyExchanges: keyExchanges,
+ MACs: macs,
},
PublicKeyCallback: func(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
pkey, err := models.SearchPublicKeyByContent(strings.TrimSpace(string(ssh.MarshalAuthorizedKey(key))))
diff --git a/routers/init.go b/routers/init.go
index d0d455ea57..18a6d03d08 100644
--- a/routers/init.go
+++ b/routers/init.go
@@ -81,7 +81,7 @@ func GlobalInit() {
checkRunMode()
if setting.InstallLock && setting.SSH.StartBuiltinServer {
- ssh.Listen(setting.SSH.ListenHost, setting.SSH.ListenPort, setting.SSH.ServerCiphers)
- log.Info("SSH server started on %s:%d. Cipher list (%v)", setting.SSH.ListenHost, setting.SSH.ListenPort, setting.SSH.ServerCiphers)
+ ssh.Listen(setting.SSH.ListenHost, setting.SSH.ListenPort, setting.SSH.ServerCiphers, setting.SSH.ServerKeyExchanges, setting.SSH.ServerMACs)
+ log.Info("SSH server started on %s:%d. Cipher list (%v), key exchange algorithms (%v), MACs (%v)", setting.SSH.ListenHost, setting.SSH.ListenPort, setting.SSH.ServerCiphers, setting.SSH.ServerKeyExchanges, setting.SSH.ServerMACs)
}
}