update sk-api to version 2 for ed25519 support; ok djm

3 files changed, 29 insertions, 14 deletions

diff --git a/usr.bin/ssh/PROTOCOL.u2f b/usr.bin/ssh/PROTOCOL.u2f
index a587480bea5..bd60f9fac5f 100644
--- a/usr.bin/ssh/PROTOCOL.u2f
+++ b/usr.bin/ssh/PROTOCOL.u2f
@@ -138,7 +138,7 @@ The signature returned from U2F hardware takes the following format:
 For use in the SSH protocol, we wish to avoid server-side parsing of ASN.1
 format data in the pre-authentication attack surface. Therefore, the
 signature format used on the wire in SSH2_USERAUTH_REQUEST packets will
-be reformatted slightly:
+be reformatted slightly and the ecdsa_signature_blob value has the encoding:
 
 	mpint		r
 	mpint		s
@@ -184,6 +184,10 @@ The middleware library need only expose a handful of functions:
 	/* Flags */
 	#define SSH_SK_USER_PRESENCE_REQD	0x01
 
+	/* Algs */
+	#define SSH_SK_ECDSA                   0x00
+	#define SSH_SK_ED25519                 0x01
+
 	struct sk_enroll_response {
 		uint8_t *public_key;
 		size_t public_key_len;
@@ -208,12 +212,12 @@ The middleware library need only expose a handful of functions:
 	uint32_t sk_api_version(void);
 
 	/* Enroll a U2F key (private key generation) */
-	int sk_enroll(const uint8_t *challenge, size_t challenge_len,
+	int sk_enroll(int alg, const uint8_t *challenge, size_t challenge_len,
 	    const char *application, uint8_t flags,
 	    struct sk_enroll_response **enroll_response);
 
 	/* Sign a challenge */
-	int sk_sign(const uint8_t *message, size_t message_len,
+	int sk_sign(int alg, const uint8_t *message, size_t message_len,
 	    const char *application,
 	    const uint8_t *key_handle, size_t key_handle_len,
 	    uint8_t flags, struct sk_sign_response **sign_response);
diff --git a/usr.bin/ssh/sk-api.h b/usr.bin/ssh/sk-api.h
index 1de73342543..0ceff54232f 100644
--- a/usr.bin/ssh/sk-api.h
+++ b/usr.bin/ssh/sk-api.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sk-api.h,v 1.1 2019/10/31 21:16:20 djm Exp $ */
+/* $OpenBSD: sk-api.h,v 1.2 2019/11/12 19:32:30 markus Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -24,6 +24,10 @@
 /* Flags */
 #define SSH_SK_USER_PRESENCE_REQD	0x01
 
+/* Algs */
+#define SSH_SK_ECDSA			0x00
+#define SSH_SK_ED25519			0x01
+
 struct sk_enroll_response {
 	uint8_t *public_key;
 	size_t public_key_len;
@@ -44,19 +48,19 @@ struct sk_sign_response {
 	size_t sig_s_len;
 };
 
-#define SSH_SK_VERSION_MAJOR		0x00010000 /* current API version */
+#define SSH_SK_VERSION_MAJOR		0x00020000 /* current API version */
 #define SSH_SK_VERSION_MAJOR_MASK	0xffff0000
 
 /* Return the version of the middleware API */
 uint32_t sk_api_version(void);
 
 /* Enroll a U2F key (private key generation) */
-int sk_enroll(const uint8_t *challenge, size_t challenge_len,
+int sk_enroll(int alg, const uint8_t *challenge, size_t challenge_len,
     const char *application, uint8_t flags,
     struct sk_enroll_response **enroll_response);
 
 /* Sign a challenge */
-int sk_sign(const uint8_t *message, size_t message_len,
+int sk_sign(int alg, const uint8_t *message, size_t message_len,
     const char *application, const uint8_t *key_handle, size_t key_handle_len,
     uint8_t flags, struct sk_sign_response **sign_response);
 
diff --git a/usr.bin/ssh/ssh-sk.c b/usr.bin/ssh/ssh-sk.c
index 0c75e30c34d..57f049c6bf2 100644
--- a/usr.bin/ssh/ssh-sk.c
+++ b/usr.bin/ssh/ssh-sk.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-sk.c,v 1.6 2019/11/12 19:31:45 markus Exp $ */
+/* $OpenBSD: ssh-sk.c,v 1.7 2019/11/12 19:32:30 markus Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -45,12 +45,12 @@ struct sshsk_provider {
 	uint32_t (*sk_api_version)(void);
 
 	/* Enroll a U2F key (private key generation) */
-	int (*sk_enroll)(const uint8_t *challenge, size_t challenge_len,
-	    const char *application, uint8_t flags,
+	int (*sk_enroll)(int alg, const uint8_t *challenge,
+	    size_t challenge_len, const char *application, uint8_t flags,
 	    struct sk_enroll_response **enroll_response);
 
 	/* Sign a challenge */
-	int (*sk_sign)(const uint8_t *message, size_t message_len,
+	int (*sk_sign)(int alg, const uint8_t *message, size_t message_len,
 	    const char *application,
 	    const uint8_t *key_handle, size_t key_handle_len,
 	    uint8_t flags, struct sk_sign_response **sign_response);
@@ -239,13 +239,17 @@ sshsk_enroll(int type, const char *provider_path, const char *application,
 	size_t challenge_len;
 	struct sk_enroll_response *resp = NULL;
 	int r = SSH_ERR_INTERNAL_ERROR;
+	int alg;
 
 	*keyp = NULL;
 	if (attest)
 		sshbuf_reset(attest);
 	switch (type) {
 	case KEY_ECDSA_SK:
+		alg = SSH_SK_ECDSA;
+		break;
 	case KEY_ED25519_SK:
+		alg = SSH_SK_ED25519;
 		break;
 	default:
 		error("%s: unsupported key type", __func__);
@@ -283,7 +287,7 @@ sshsk_enroll(int type, const char *provider_path, const char *application,
 	}
 	/* XXX validate flags? */
 	/* enroll key */
-	if ((r = skp->sk_enroll(challenge, challenge_len, application,
+	if ((r = skp->sk_enroll(alg, challenge, challenge_len, application,
 	    flags, &resp)) != 0) {
 		error("Security key provider %s returned failure %d",
 		    provider_path, r);
@@ -423,7 +427,7 @@ sshsk_sign(const char *provider_path, const struct sshkey *key,
 {
 	struct sshsk_provider *skp = NULL;
 	int r = SSH_ERR_INTERNAL_ERROR;
-	int type;
+	int type, alg;
 	struct sk_sign_response *resp = NULL;
 	struct sshbuf *inner_sig = NULL, *sig = NULL;
 	uint8_t message[32];
@@ -435,7 +439,10 @@ sshsk_sign(const char *provider_path, const struct sshkey *key,
 	type = sshkey_type_plain(key->type);
 	switch (type) {
 	case KEY_ECDSA_SK:
+		alg = SSH_SK_ECDSA;
+		break;
 	case KEY_ED25519_SK:
+		alg = SSH_SK_ED25519;
 		break;
 	default:
 		return SSH_ERR_INVALID_ARGUMENT;
@@ -458,7 +465,7 @@ sshsk_sign(const char *provider_path, const struct sshkey *key,
 		r = SSH_ERR_INTERNAL_ERROR;
 		goto out;
 	}
-	if ((r = skp->sk_sign(message, sizeof(message),
+	if ((r = skp->sk_sign(alg, message, sizeof(message),
 	    key->sk_application,
 	    sshbuf_ptr(key->sk_key_handle), sshbuf_len(key->sk_key_handle),
 	    key->sk_flags, &resp)) != 0) {