upstream: Refactor signing - use sshkey_sign for everything,

including the new U2F signatures.

Don't use sshsk_ecdsa_sign() directly, instead make it reachable via
sshkey_sign() like all other signature operations. This means that
we need to add a provider argument to sshkey_sign(), so most of this
change is mechanically adding that.

Suggested by / ok markus@

OpenBSD-Commit-ID: d5193a03fcfa895085d91b2b83d984a9fde76c8c

14 files changed, 82 insertions, 72 deletions

diff --git a/krl.c b/krl.c
index a7f690955..89cb433bd 100644
--- a/krl.c
+++ b/krl.c
@@ -14,7 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $OpenBSD: krl.c,v 1.44 2019/09/06 04:53:27 djm Exp $ */
+/* $OpenBSD: krl.c,v 1.45 2019/10/31 21:23:19 djm Exp $ */
 
 #include "includes.h"
 
@@ -813,7 +813,7 @@ ssh_krl_to_blob(struct ssh_krl *krl, struct sshbuf *buf,
                         goto out;
 
                 if ((r = sshkey_sign(sign_keys[i], &sblob, &slen,
-                    sshbuf_ptr(buf), sshbuf_len(buf), NULL, 0)) != 0)
+                    sshbuf_ptr(buf), sshbuf_len(buf), NULL, NULL, 0)) != 0)
                         goto out;
                 KRL_DBG(("%s: signature sig len %zu", __func__, slen));
                 if ((r = sshbuf_put_string(buf, sblob, slen)) != 0)
diff --git a/monitor.c b/monitor.c
index 00af44f98..a884d5f9d 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.199 2019/10/07 23:10:38 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.200 2019/10/31 21:23:19 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -678,7 +678,7 @@ mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m)
 
         if ((key = get_hostkey_by_index(keyid)) != NULL) {
                 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg,
-                    compat)) != 0)
+                    NULL, compat)) != 0)
                         fatal("%s: sshkey_sign failed: %s",
                             __func__, ssh_err(r));
         } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL &&
diff --git a/monitor_wrap.c b/monitor_wrap.c
index 4169b7604..d20dc5191 100644
--- a/monitor_wrap.c
+++ b/monitor_wrap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.c,v 1.113 2019/06/28 13:35:04 deraadt Exp $ */
+/* $OpenBSD: monitor_wrap.c,v 1.114 2019/10/31 21:23:19 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -215,7 +215,8 @@ mm_choose_dh(int min, int nbits, int max)
 
 int
 mm_sshkey_sign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
-    const u_char *data, size_t datalen, const char *hostkey_alg, u_int compat)
+    const u_char *data, size_t datalen, const char *hostkey_alg,
+    const char *sk_provider, u_int compat)
 {
         struct kex *kex = *pmonitor->m_pkex;
         struct sshbuf *m;
@@ -223,7 +224,8 @@ mm_sshkey_sign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
         int r;
 
         debug3("%s entering", __func__);
-
+        if (sk_provider != NULL)
+                fatal("%s: sk_provider != NULL", __func__);
         if ((m = sshbuf_new()) == NULL)
                 fatal("%s: sshbuf_new failed", __func__);
         if ((r = sshbuf_put_u32(m, ndx)) != 0 ||
diff --git a/monitor_wrap.h b/monitor_wrap.h
index 191277f3a..76330fc60 100644
--- a/monitor_wrap.h
+++ b/monitor_wrap.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.h,v 1.42 2019/09/06 05:23:55 djm Exp $ */
+/* $OpenBSD: monitor_wrap.h,v 1.43 2019/10/31 21:23:19 djm Exp $ */
 
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
@@ -45,7 +45,7 @@ int mm_is_monitor(void);
 DH *mm_choose_dh(int, int, int);
 #endif
 int mm_sshkey_sign(struct ssh *, struct sshkey *, u_char **, size_t *,
-    const u_char *, size_t, const char *, u_int compat);
+    const u_char *, size_t, const char *, const char *, u_int compat);
 void mm_inform_authserv(char *, char *);
 struct passwd *mm_getpwnamallow(struct ssh *, const char *);
 char *mm_auth2_read_banner(void);
diff --git a/ssh-agent.c b/ssh-agent.c
index 6bf9536fb..07f19c53a 100644
--- a/ssh-agent.c
+++ b/ssh-agent.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-agent.c,v 1.238 2019/10/31 21:22:01 djm Exp $ */
+/* $OpenBSD: ssh-agent.c,v 1.239 2019/10/31 21:23:19 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -430,12 +430,13 @@ process_sign_request2(SocketEntry *e)
                 if ((r = provider_sign(id->sk_provider, id->key, &signature,
                     &slen, data, dlen, agent_decode_alg(key, flags),
                     compat)) != 0) {
-                        error("%s: sshkey_sign: %s", __func__, ssh_err(r));
+                        error("%s: sign: %s", __func__, ssh_err(r));
                         goto send;
                 }
         } else {
                 if ((r = sshkey_sign(id->key, &signature, &slen,
-                    data, dlen, agent_decode_alg(key, flags), compat)) != 0) {
+                    data, dlen, agent_decode_alg(key, flags),
+                    NULL, compat)) != 0) {
                         error("%s: sshkey_sign: %s", __func__, ssh_err(r));
                         goto send;
                 }
diff --git a/ssh-keygen.c b/ssh-keygen.c
index ad7a2b4e0..14bf2560d 100644
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keygen.c,v 1.357 2019/10/31 21:17:09 djm Exp $ */
+/* $OpenBSD: ssh-keygen.c,v 1.358 2019/10/31 21:23:19 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -577,8 +577,10 @@ do_convert_private_ssh2(struct sshbuf *b)
                 error("%s: remaining bytes in key blob %d", __func__, rlen);
 
         /* try the key */
-        if (sshkey_sign(key, &sig, &slen, data, sizeof(data), NULL, 0) != 0 ||
-            sshkey_verify(key, sig, slen, data, sizeof(data), NULL, 0) != 0) {
+        if (sshkey_sign(key, &sig, &slen, data, sizeof(data),
+            NULL, NULL, 0) != 0 ||
+            sshkey_verify(key, sig, slen, data, sizeof(data),
+            NULL, 0) != 0) {
                 sshkey_free(key);
                 free(sig);
                 return NULL;
@@ -1709,7 +1711,7 @@ load_pkcs11_key(char *path)
 static int
 agent_signer(struct sshkey *key, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen,
-    const char *alg, u_int compat, void *ctx)
+    const char *alg, const char *sk_provider, u_int compat, void *ctx)
 {
         int *agent_fdp = (int *)ctx;
 
@@ -1821,11 +1823,13 @@ do_ca_sign(struct passwd *pw, const char *ca_key_path, int prefer_agent,
 
                 if (agent_fd != -1 && (ca->flags & SSHKEY_FLAG_EXT) != 0) {
                         if ((r = sshkey_certify_custom(public, ca,
-                            key_type_name, agent_signer, &agent_fd)) != 0)
+                            key_type_name, sk_provider, agent_signer,
+                            &agent_fd)) != 0)
                                 fatal("Couldn't certify key %s via agent: %s",
                                     tmp, ssh_err(r));
                 } else {
-                        if ((sshkey_certify(public, ca, key_type_name)) != 0)
+                        if ((sshkey_certify(public, ca, key_type_name,
+                            sk_provider)) != 0)
                                 fatal("Couldn't certify key %s: %s",
                                     tmp, ssh_err(r));
                 }
@@ -2507,7 +2511,7 @@ sign_one(struct sshkey *signkey, const char *filename, int fd,
                 else
                         fprintf(stderr, "Signing file %s\n", filename);
         }
-        if ((r = sshsig_sign_fd(signkey, NULL, fd, sig_namespace,
+        if ((r = sshsig_sign_fd(signkey, NULL, sk_provider, fd, sig_namespace,
             &sigbuf, signer, signer_ctx)) != 0) {
                 error("Signing %s failed: %s", filename, ssh_err(r));
                 goto out;
diff --git a/ssh-keysign.c b/ssh-keysign.c
index 6cfd5b46c..d6aa6361d 100644
--- a/ssh-keysign.c
+++ b/ssh-keysign.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keysign.c,v 1.61 2019/10/02 00:42:30 djm Exp $ */
+/* $OpenBSD: ssh-keysign.c,v 1.62 2019/10/31 21:23:19 djm Exp $ */
 /*
  * Copyright (c) 2002 Markus Friedl.  All rights reserved.
  *
@@ -277,8 +277,8 @@ main(int argc, char **argv)
                     sshkey_type(key), fp ? fp : "");
         }
 
-        if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen, NULL, 0))
-            != 0)
+        if ((r = sshkey_sign(keys[i], &signature, &slen, data, dlen,
+            NULL, NULL, 0)) != 0)
                 fatal("sshkey_sign failed: %s", ssh_err(r));
         free(data);
 
diff --git a/ssh_api.c b/ssh_api.c
index 03dac0982..e0b195521 100644
--- a/ssh_api.c
+++ b/ssh_api.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh_api.c,v 1.18 2019/09/13 04:36:43 dtucker Exp $ */
+/* $OpenBSD: ssh_api.c,v 1.19 2019/10/31 21:23:19 djm Exp $ */
 /*
  * Copyright (c) 2012 Markus Friedl.  All rights reserved.
  *
@@ -54,7 +54,7 @@ int	_ssh_host_key_sign(struct ssh *, struct sshkey *, struct sshkey *,
  */
 int     use_privsep = 0;
 int     mm_sshkey_sign(struct sshkey *, u_char **, u_int *,
-    u_char *, u_int, char *, u_int);
+    const u_char *, u_int, const char *, const char *, u_int);
 
 #ifdef WITH_OPENSSL
 DH      *mm_choose_dh(int, int, int);
@@ -66,7 +66,8 @@ u_int session_id2_len = 0;
 
 int
 mm_sshkey_sign(struct sshkey *key, u_char **sigp, u_int *lenp,
-    u_char *data, u_int datalen, char *alg, u_int compat)
+    const u_char *data, u_int datalen, const char *alg, const char *sk_provider,
+    u_int compat)
 {
         return (-1);
 }
@@ -568,5 +569,5 @@ _ssh_host_key_sign(struct ssh *ssh, struct sshkey *privkey,
     const u_char *data, size_t dlen, const char *alg)
 {
         return sshkey_sign(privkey, signature, slen, data, dlen,
-            alg, ssh->compat);
+            alg, NULL, ssh->compat);
 }
diff --git a/sshconnect2.c b/sshconnect2.c
index 62f0c3e76..867d463d6 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect2.c,v 1.309 2019/10/31 21:18:28 djm Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.310 2019/10/31 21:23:19 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
@@ -1178,19 +1178,8 @@ identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
                 }
                 sign_key = prv;
         }
-
-        if (sshkey_type_plain(sign_key->type) == KEY_ECDSA_SK) {
-                if (options.sk_provider == NULL) {
-                        /* Shouldn't happen here; checked in pubkey_prepare() */
-                        fatal("%s: missing SecurityKeyProvider", __func__);
-                }
-                if ((r = sshsk_ecdsa_sign(options.sk_provider, sign_key,
-                    sigp, lenp, data, datalen, compat)) != 0) {
-                        debug("%s: sshsk_ecdsa_sign: %s", __func__, ssh_err(r));
-                        goto out;
-                }
-        } else if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen,
-            alg, compat)) != 0) {
+        if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen,
+            alg, options.sk_provider, compat)) != 0) {
                 debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
                 goto out;
         }
diff --git a/sshd.c b/sshd.c
index cf7af1c61..e782a99f2 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.538 2019/10/29 07:47:27 dtucker Exp $ */
+/* $OpenBSD: sshd.c,v 1.539 2019/10/31 21:23:19 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2209,17 +2209,17 @@ sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey,
         if (use_privsep) {
                 if (privkey) {
                         if (mm_sshkey_sign(ssh, privkey, signature, slenp,
-                            data, dlen, alg, ssh->compat) < 0)
+                            data, dlen, alg, NULL, ssh->compat) < 0)
                                 fatal("%s: privkey sign failed", __func__);
                 } else {
                         if (mm_sshkey_sign(ssh, pubkey, signature, slenp,
-                            data, dlen, alg, ssh->compat) < 0)
+                            data, dlen, alg, NULL, ssh->compat) < 0)
                                 fatal("%s: pubkey sign failed", __func__);
                 }
         } else {
                 if (privkey) {
                         if (sshkey_sign(privkey, signature, slenp, data, dlen,
-                            alg, ssh->compat) < 0)
+                            alg, NULL, ssh->compat) < 0)
                                 fatal("%s: privkey sign failed", __func__);
                 } else {
                         if ((r = ssh_agent_sign(auth_sock, pubkey,
diff --git a/sshkey.c b/sshkey.c
index d87fee8ee..4744dfbef 100644
--- a/sshkey.c
+++ b/sshkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.c,v 1.85 2019/10/31 21:15:14 djm Exp $ */
+/* $OpenBSD: sshkey.c,v 1.86 2019/10/31 21:23:19 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Alexander von Gernler.  All rights reserved.
@@ -57,6 +57,7 @@
 #define SSHKEY_INTERNAL
 #include "sshkey.h"
 #include "match.h"
+#include "ssh-sk.h"
 
 #ifdef WITH_XMSS
 #include "sshkey-xmss.h"
@@ -2658,7 +2659,8 @@ sshkey_check_sigtype(const u_char *sig, size_t siglen,
 int
 sshkey_sign(struct sshkey *key,
     u_char **sigp, size_t *lenp,
-    const u_char *data, size_t datalen, const char *alg, u_int compat)
+    const u_char *data, size_t datalen,
+    const char *alg, const char *sk_provider, u_int compat)
 {
         int was_shielded = sshkey_is_shielded(key);
         int r2, r = SSH_ERR_INTERNAL_ERROR;
@@ -2682,6 +2684,11 @@ sshkey_sign(struct sshkey *key,
         case KEY_ECDSA:
                 r = ssh_ecdsa_sign(key, sigp, lenp, data, datalen, compat);
                 break;
+        case KEY_ECDSA_SK_CERT:
+        case KEY_ECDSA_SK:
+                r = sshsk_ecdsa_sign(sk_provider, key, sigp, lenp,
+                    data, datalen, compat);
+                break;
 # endif /* OPENSSL_HAS_ECC */
         case KEY_RSA_CERT:
         case KEY_RSA:
@@ -2802,7 +2809,7 @@ sshkey_drop_cert(struct sshkey *k)
 /* Sign a certified key, (re-)generating the signed certblob. */
 int
 sshkey_certify_custom(struct sshkey *k, struct sshkey *ca, const char *alg,
-    sshkey_certify_signer *signer, void *signer_ctx)
+    const char *sk_provider, sshkey_certify_signer *signer, void *signer_ctx)
 {
         struct sshbuf *principals = NULL;
         u_char *ca_blob = NULL, *sig_blob = NULL, nonce[32];
@@ -2934,7 +2941,7 @@ sshkey_certify_custom(struct sshkey *k, struct sshkey *ca, const char *alg,
 
         /* Sign the whole mess */
         if ((ret = signer(ca, &sig_blob, &sig_len, sshbuf_ptr(cert),
-            sshbuf_len(cert), alg, 0, signer_ctx)) != 0)
+            sshbuf_len(cert), alg, sk_provider, 0, signer_ctx)) != 0)
                 goto out;
         /* Check and update signature_type against what was actually used */
         if ((ret = sshkey_get_sigtype(sig_blob, sig_len, &sigtype)) != 0)
@@ -2964,17 +2971,20 @@ sshkey_certify_custom(struct sshkey *k, struct sshkey *ca, const char *alg,
 static int
 default_key_sign(struct sshkey *key, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen,
-    const char *alg, u_int compat, void *ctx)
+    const char *alg, const char *sk_provider, u_int compat, void *ctx)
 {
         if (ctx != NULL)
                 return SSH_ERR_INVALID_ARGUMENT;
-        return sshkey_sign(key, sigp, lenp, data, datalen, alg, compat);
+        return sshkey_sign(key, sigp, lenp, data, datalen, alg,
+            sk_provider, compat);
 }
 
 int
-sshkey_certify(struct sshkey *k, struct sshkey *ca, const char *alg)
+sshkey_certify(struct sshkey *k, struct sshkey *ca, const char *alg,
+    const char *sk_provider)
 {
-        return sshkey_certify_custom(k, ca, alg, default_key_sign, NULL);
+        return sshkey_certify_custom(k, ca, alg, sk_provider,
+            default_key_sign, NULL);
 }
 
 int
diff --git a/sshkey.h b/sshkey.h
index 2edcb13ab..1d36a24a9 100644
--- a/sshkey.h
+++ b/sshkey.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.h,v 1.35 2019/10/31 21:15:14 djm Exp $ */
+/* $OpenBSD: sshkey.h,v 1.36 2019/10/31 21:23:19 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -189,12 +189,13 @@ size_t	 sshkey_format_cert_validity(const struct sshkey_cert *,
     char *, size_t) __attribute__((__bounded__(__string__, 2, 3)));
 int      sshkey_check_cert_sigtype(const struct sshkey *, const char *);
 
-int      sshkey_certify(struct sshkey *, struct sshkey *, const char *);
+int      sshkey_certify(struct sshkey *, struct sshkey *,
+    const char *, const char *);
 /* Variant allowing use of a custom signature function (e.g. for ssh-agent) */
 typedef int sshkey_certify_signer(struct sshkey *, u_char **, size_t *,
-    const u_char *, size_t, const char *, u_int, void *);
+    const u_char *, size_t, const char *, const char *, u_int, void *);
 int      sshkey_certify_custom(struct sshkey *, struct sshkey *, const char *,
-    sshkey_certify_signer *, void *);
+    const char *, sshkey_certify_signer *, void *);
 
 int              sshkey_ecdsa_nid_from_name(const char *);
 int              sshkey_curve_name_to_nid(const char *);
@@ -223,7 +224,7 @@ int	 sshkey_plain_to_blob(const struct sshkey *, u_char **, size_t *);
 int      sshkey_putb_plain(const struct sshkey *, struct sshbuf *);
 
 int      sshkey_sign(struct sshkey *, u_char **, size_t *,
-    const u_char *, size_t, const char *, u_int);
+    const u_char *, size_t, const char *, const char *, u_int);
 int      sshkey_verify(const struct sshkey *, const u_char *, size_t,
     const u_char *, size_t, const char *, u_int);
 int      sshkey_check_sigtype(const u_char *, size_t, const char *);
diff --git a/sshsig.c b/sshsig.c
index b19cd077d..8c7aba1b9 100644
--- a/sshsig.c
+++ b/sshsig.c
@@ -151,8 +151,9 @@ done:
 
 static int
 sshsig_wrap_sign(struct sshkey *key, const char *hashalg,
-    const struct sshbuf *h_message, const char *sig_namespace,
-    struct sshbuf **out, sshsig_signer *signer, void *signer_ctx)
+    const char *sk_provider, const struct sshbuf *h_message,
+    const char *sig_namespace, struct sshbuf **out,
+    sshsig_signer *signer, void *signer_ctx)
 {
         int r;
         size_t slen = 0;
@@ -184,14 +185,14 @@ sshsig_wrap_sign(struct sshkey *key, const char *hashalg,
         if (signer != NULL) {
                 if ((r = signer(key, &sig, &slen,
                     sshbuf_ptr(tosign), sshbuf_len(tosign),
-                    sign_alg, 0, signer_ctx)) != 0) {
+                    sign_alg, sk_provider, 0, signer_ctx)) != 0) {
                         error("Couldn't sign message: %s", ssh_err(r));
                         goto done;
                 }
         } else {
                 if ((r = sshkey_sign(key, &sig, &slen,
                     sshbuf_ptr(tosign), sshbuf_len(tosign),
-                    sign_alg, 0)) != 0) {
+                    sign_alg, sk_provider, 0)) != 0) {
                         error("Couldn't sign message: %s", ssh_err(r));
                         goto done;
                 }
@@ -425,7 +426,7 @@ hash_buffer(const struct sshbuf *m, const char *hashalg, struct sshbuf **bp)
 }
 
 int
-sshsig_signb(struct sshkey *key, const char *hashalg,
+sshsig_signb(struct sshkey *key, const char *hashalg, const char *sk_provider,
     const struct sshbuf *message, const char *sig_namespace,
     struct sshbuf **out, sshsig_signer *signer, void *signer_ctx)
 {
@@ -440,8 +441,8 @@ sshsig_signb(struct sshkey *key, const char *hashalg,
                 error("%s: hash_buffer failed: %s", __func__, ssh_err(r));
                 goto out;
         }
-        if ((r = sshsig_wrap_sign(key, hashalg, b, sig_namespace, out,
-            signer, signer_ctx)) != 0)
+        if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, b,
+            sig_namespace, out, signer, signer_ctx)) != 0)
                 goto out;
         /* success */
         r = 0;
@@ -551,7 +552,7 @@ hash_file(int fd, const char *hashalg, struct sshbuf **bp)
 }
 
 int
-sshsig_sign_fd(struct sshkey *key, const char *hashalg,
+sshsig_sign_fd(struct sshkey *key, const char *hashalg, const char *sk_provider,
     int fd, const char *sig_namespace, struct sshbuf **out,
     sshsig_signer *signer, void *signer_ctx)
 {
@@ -566,8 +567,8 @@ sshsig_sign_fd(struct sshkey *key, const char *hashalg,
                 error("%s: hash_file failed: %s", __func__, ssh_err(r));
                 return r;
         }
-        if ((r = sshsig_wrap_sign(key, hashalg, b, sig_namespace, out,
-            signer, signer_ctx)) != 0)
+        if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, b,
+            sig_namespace, out, signer, signer_ctx)) != 0)
                 goto out;
         /* success */
         r = 0;
diff --git a/sshsig.h b/sshsig.h
index e3eeb601b..487db116c 100644
--- a/sshsig.h
+++ b/sshsig.h
@@ -22,7 +22,7 @@ struct sshkey;
 struct sshsigopt;
 
 typedef int sshsig_signer(struct sshkey *, u_char **, size_t *,
-    const u_char *, size_t, const char *, u_int, void *);
+    const u_char *, size_t, const char *, const char *, u_int, void *);
 
 /* Buffer-oriented API */
 
@@ -32,8 +32,9 @@ typedef int sshsig_signer(struct sshkey *, u_char **, size_t *,
  * out is populated with the detached signature, or NULL on failure.
  */
 int sshsig_signb(struct sshkey *key, const char *hashalg,
-    const struct sshbuf *message, const char *sig_namespace,
-    struct sshbuf **out, sshsig_signer *signer, void *signer_ctx);
+    const char *sk_provider, const struct sshbuf *message,
+    const char *sig_namespace, struct sshbuf **out,
+    sshsig_signer *signer, void *signer_ctx);
 
 /*
  * Verifies that a detached signature is valid and optionally returns key
@@ -52,8 +53,8 @@ int sshsig_verifyb(struct sshbuf *signature,
  * out is populated with the detached signature, or NULL on failure.
  */
 int sshsig_sign_fd(struct sshkey *key, const char *hashalg,
-    int fd, const char *sig_namespace, struct sshbuf **out,
-    sshsig_signer *signer, void *signer_ctx);
+    const char *sk_provider, int fd, const char *sig_namespace,
+    struct sshbuf **out, sshsig_signer *signer, void *signer_ctx);
 
 /*
  * Verifies that a detached signature over a file is valid and optionally