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Configurable SSH key exchange algorithm and MAC suite #2806

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Merged
merged 2 commits into from
Nov 2, 2017
Merged

Configurable SSH key exchange algorithm and MAC suite #2806

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Configurable SSH key exchange algorithm and MAC suite
virvum Oct 30, 2017
065b5b9
Merge branch 'master' into master
lafriks Nov 2, 2017
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6 changes: 6 additions & 0 deletions conf/app.ini
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Original file line number Diff line number Diff line change
Expand Up @@ -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 =
Expand Down
12 changes: 12 additions & 0 deletions modules/setting/setting.go
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Expand Up @@ -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"`
Expand All @@ -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",
}

Expand Down Expand Up @@ -732,6 +736,14 @@ func NewContext() {
if len(serverCiphers) > 0 {
SSH.ServerCiphers = serverCiphers
}
serverKeyExchanges := sec.Key("SSH_SERVER_KEY_EXCHANGES").Strings(",")
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@sapk sapk Nov 2, 2017 •
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~~~For example if SSH_SERVER_KEY_EXCHANGES is not set. serverKeyExchanges = "," -> len(serverKeyExchanges) > 0 == true~~~

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@sapk sapk Nov 2, 2017 •
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Sorry misread ... the .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)
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6 changes: 4 additions & 2 deletions modules/ssh/ssh.go
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Expand Up @@ -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))))
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4 changes: 2 additions & 2 deletions routers/init.go
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Expand Up @@ -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)
}
}