upstream commit

switch auth2-pubkey.c to modern APIs; with & ok djm@

Upstream-ID: 8f08d4316eb1b0c4ffe4a206c05cdd45ed1daf07

5 files changed, 148 insertions, 112 deletions

diff --git a/auth2-hostbased.c b/auth2-hostbased.c
index 92ac20d90..eddf797fe 100644
--- a/auth2-hostbased.c
+++ b/auth2-hostbased.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-hostbased.c,v 1.27 2017/05/30 08:52:19 markus Exp $ */
+/* $OpenBSD: auth2-hostbased.c,v 1.28 2017/05/30 14:10:53 markus Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -138,8 +138,8 @@ userauth_hostbased(Authctxt *authctxt)
         /* test for allowed key and correct signature */
         authenticated = 0;
         if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
-            PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
-                        buffer_len(&b))) == 1)
+            PRIVSEP(sshkey_verify(key, sig, slen, buffer_ptr(&b),
+                        buffer_len(&b), 0)) == 0)
                 authenticated = 1;
 
         buffer_free(&b);
diff --git a/auth2-pubkey.c b/auth2-pubkey.c
index 38940a6d9..a4a091113 100644
--- a/auth2-pubkey.c
+++ b/auth2-pubkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-pubkey.c,v 1.63 2017/05/30 08:52:19 markus Exp $ */
+/* $OpenBSD: auth2-pubkey.c,v 1.64 2017/05/30 14:10:53 markus Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -52,7 +52,7 @@
 #include "misc.h"
 #include "servconf.h"
 #include "compat.h"
-#include "key.h"
+#include "sshkey.h"
 #include "hostfile.h"
 #include "auth.h"
 #include "pathnames.h"
@@ -77,40 +77,50 @@ extern u_int session_id2_len;
 static int
 userauth_pubkey(Authctxt *authctxt)
 {
-        Buffer b;
+        struct ssh *ssh = active_state; /* XXX */
+        struct sshbuf *b;
         struct sshkey *key = NULL;
-        char *pkalg, *userstyle, *fp = NULL;
-        u_char *pkblob, *sig;
-        u_int alen, blen, slen;
-        int have_sig, pktype;
+        char *pkalg, *userstyle = NULL, *fp = NULL;
+        u_char *pkblob, *sig, have_sig;
+        size_t blen, slen;
+        int r, pktype;
         int authenticated = 0;
 
         if (!authctxt->valid) {
                 debug2("%s: disabled because of invalid user", __func__);
                 return 0;
         }
-        have_sig = packet_get_char();
-        if (datafellows & SSH_BUG_PKAUTH) {
+        if ((r = sshpkt_get_u8(ssh, &have_sig)) != 0)
+                fatal("%s: sshpkt_get_u8 failed: %s", __func__, ssh_err(r));
+        if (ssh->compat & SSH_BUG_PKAUTH) {
                 debug2("%s: SSH_BUG_PKAUTH", __func__);
+                if ((b = sshbuf_new()) == NULL)
+                        fatal("%s: sshbuf_new failed", __func__);
                 /* no explicit pkalg given */
-                pkblob = packet_get_string(&blen);
-                buffer_init(&b);
-                buffer_append(&b, pkblob, blen);
                 /* so we have to extract the pkalg from the pkblob */
-                pkalg = buffer_get_string(&b, &alen);
-                buffer_free(&b);
+                /* XXX use sshbuf_from() */
+                if ((r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
+                    (r = sshbuf_put(b, pkblob, blen)) != 0 ||
+                    (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0)
+                        fatal("%s: failed: %s", __func__, ssh_err(r));
+                sshbuf_free(b);
         } else {
-                pkalg = packet_get_string(&alen);
-                pkblob = packet_get_string(&blen);
+                if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
+                    (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0)
+                        fatal("%s: sshpkt_get_cstring failed: %s",
+                            __func__, ssh_err(r));
         }
-        pktype = key_type_from_name(pkalg);
+        pktype = sshkey_type_from_name(pkalg);
         if (pktype == KEY_UNSPEC) {
                 /* this is perfectly legal */
                 logit("%s: unsupported public key algorithm: %s",
                     __func__, pkalg);
                 goto done;
         }
-        key = key_from_blob(pkblob, blen);
+        if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
+                error("%s: could not parse key: %s", __func__, ssh_err(r));
+                goto done;
+        }
         if (key == NULL) {
                 error("%s: cannot decode key: %s", __func__, pkalg);
                 goto done;
@@ -120,15 +130,15 @@ userauth_pubkey(Authctxt *authctxt)
                     "(received %d, expected %d)", __func__, key->type, pktype);
                 goto done;
         }
-        if (key_type_plain(key->type) == KEY_RSA &&
-            (datafellows & SSH_BUG_RSASIGMD5) != 0) {
+        if (sshkey_type_plain(key->type) == KEY_RSA &&
+            (ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
                 logit("Refusing RSA key because client uses unsafe "
                     "signature scheme");
                 goto done;
         }
         fp = sshkey_fingerprint(key, options.fingerprint_hash, SSH_FP_DEFAULT);
         if (auth2_userkey_already_used(authctxt, key)) {
-                logit("refusing previously-used %s key", key_type(key));
+                logit("refusing previously-used %s key", sshkey_type(key));
                 goto done;
         }
         if (match_pattern_list(sshkey_ssh_name(key),
@@ -141,54 +151,68 @@ userauth_pubkey(Authctxt *authctxt)
         if (have_sig) {
                 debug3("%s: have signature for %s %s",
                     __func__, sshkey_type(key), fp);
-                sig = packet_get_string(&slen);
-                packet_check_eom();
-                buffer_init(&b);
-                if (datafellows & SSH_OLD_SESSIONID) {
-                        buffer_append(&b, session_id2, session_id2_len);
+                if ((r = sshpkt_get_string(ssh, &sig, &slen)) != 0 ||
+                    (r = sshpkt_get_end(ssh)) != 0)
+                        fatal("%s: %s", __func__, ssh_err(r));
+                if ((b = sshbuf_new()) == NULL)
+                        fatal("%s: sshbuf_new failed", __func__);
+                if (ssh->compat & SSH_OLD_SESSIONID) {
+                        if ((r = sshbuf_put(b, session_id2,
+                            session_id2_len)) != 0)
+                                fatal("%s: sshbuf_put session id: %s",
+                                    __func__, ssh_err(r));
                 } else {
-                        buffer_put_string(&b, session_id2, session_id2_len);
+                        if ((r = sshbuf_put_string(b, session_id2,
+                            session_id2_len)) != 0)
+                                fatal("%s: sshbuf_put_string session id: %s",
+                                    __func__, ssh_err(r));
                 }
                 /* reconstruct packet */
-                buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
                 xasprintf(&userstyle, "%s%s%s", authctxt->user,
                     authctxt->style ? ":" : "",
                     authctxt->style ? authctxt->style : "");
-                buffer_put_cstring(&b, userstyle);
-                free(userstyle);
-                buffer_put_cstring(&b,
-                    datafellows & SSH_BUG_PKSERVICE ?
-                    "ssh-userauth" :
-                    authctxt->service);
-                if (datafellows & SSH_BUG_PKAUTH) {
-                        buffer_put_char(&b, have_sig);
+                if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+                    (r = sshbuf_put_cstring(b, userstyle)) != 0 ||
+                    (r = sshbuf_put_cstring(b, ssh->compat & SSH_BUG_PKSERVICE ?
+                    "ssh-userauth" : authctxt->service)) != 0)
+                        fatal("%s: build packet failed: %s",
+                            __func__, ssh_err(r));
+                if (ssh->compat & SSH_BUG_PKAUTH) {
+                        if ((r = sshbuf_put_u8(b, have_sig)) != 0)
+                                fatal("%s: build packet failed: %s",
+                                    __func__, ssh_err(r));
                 } else {
-                        buffer_put_cstring(&b, "publickey");
-                        buffer_put_char(&b, have_sig);
-                        buffer_put_cstring(&b, pkalg);
+                        if ((r = sshbuf_put_cstring(b, "publickey")) != 0 ||
+                            (r = sshbuf_put_u8(b, have_sig)) != 0 ||
+                            (r = sshbuf_put_cstring(b, pkalg) != 0))
+                                fatal("%s: build packet failed: %s",
+                                    __func__, ssh_err(r));
                 }
-                buffer_put_string(&b, pkblob, blen);
+                if ((r = sshbuf_put_string(b, pkblob, blen)) != 0)
+                        fatal("%s: build packet failed: %s",
+                            __func__, ssh_err(r));
 #ifdef DEBUG_PK
-                buffer_dump(&b);
+                sshbuf_dump(b, stderr);
 #endif
                 pubkey_auth_info(authctxt, key, NULL);
 
                 /* test for correct signature */
                 authenticated = 0;
                 if (PRIVSEP(user_key_allowed(authctxt->pw, key, 1)) &&
-                    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
-                    buffer_len(&b))) == 1) {
+                    PRIVSEP(sshkey_verify(key, sig, slen, sshbuf_ptr(b),
+                    sshbuf_len(b), ssh->compat)) == 0) {
                         authenticated = 1;
                         /* Record the successful key to prevent reuse */
                         auth2_record_userkey(authctxt, key);
                         key = NULL; /* Don't free below */
                 }
-                buffer_free(&b);
+                sshbuf_free(b);
                 free(sig);
         } else {
                 debug("%s: test whether pkalg/pkblob are acceptable for %s %s",
                     __func__, sshkey_type(key), fp);
-                packet_check_eom();
+                if ((r = sshpkt_get_end(ssh)) != 0)
+                        fatal("%s: %s", __func__, ssh_err(r));
 
                 /* XXX fake reply and always send PK_OK ? */
                 /*
@@ -199,11 +223,13 @@ userauth_pubkey(Authctxt *authctxt)
                  * issue? -markus
                  */
                 if (PRIVSEP(user_key_allowed(authctxt->pw, key, 0))) {
-                        packet_start(SSH2_MSG_USERAUTH_PK_OK);
-                        packet_put_string(pkalg, alen);
-                        packet_put_string(pkblob, blen);
-                        packet_send();
-                        packet_write_wait();
+                        if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_PK_OK))
+                            != 0 ||
+                            (r = sshpkt_put_cstring(ssh, pkalg)) != 0 ||
+                            (r = sshpkt_put_string(ssh, pkblob, blen)) != 0 ||
+                            (r = sshpkt_send(ssh)) != 0)
+                                fatal("%s: %s", __func__, ssh_err(r));
+                        ssh_packet_write_wait(ssh);
                         authctxt->postponed = 1;
                 }
         }
@@ -212,7 +238,8 @@ userauth_pubkey(Authctxt *authctxt)
 done:
         debug2("%s: authenticated %d pkalg %s", __func__, authenticated, pkalg);
         if (key != NULL)
-                key_free(key);
+                sshkey_free(key);
+        free(userstyle);
         free(pkalg);
         free(pkblob);
         free(fp);
@@ -233,23 +260,23 @@ pubkey_auth_info(Authctxt *authctxt, const struct sshkey *key,
                 i = vasprintf(&extra, fmt, ap);
                 va_end(ap);
                 if (i < 0 || extra == NULL)
-                        fatal("%s: vasprintf failed", __func__);        
+                        fatal("%s: vasprintf failed", __func__);
         }
 
-        if (key_is_cert(key)) {
+        if (sshkey_is_cert(key)) {
                 fp = sshkey_fingerprint(key->cert->signature_key,
                     options.fingerprint_hash, SSH_FP_DEFAULT);
                 auth_info(authctxt, "%s ID %s (serial %llu) CA %s %s%s%s", 
-                    key_type(key), key->cert->key_id,
+                    sshkey_type(key), key->cert->key_id,
                     (unsigned long long)key->cert->serial,
-                    key_type(key->cert->signature_key),
+                    sshkey_type(key->cert->signature_key),
                     fp == NULL ? "(null)" : fp,
                     extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
                 free(fp);
         } else {
                 fp = sshkey_fingerprint(key, options.fingerprint_hash,
                     SSH_FP_DEFAULT);
-                auth_info(authctxt, "%s %s%s%s", key_type(key),
+                auth_info(authctxt, "%s %s%s%s", sshkey_type(key),
                     fp == NULL ? "(null)" : fp,
                     extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
                 free(fp);
@@ -762,16 +789,13 @@ match_principals_command(struct passwd *user_pw, const struct sshkey *key)
  * returns 1 if the key is allowed or 0 otherwise.
  */
 static int
-check_authkeys_file(FILE *f, char *file, struct sshkey* key, struct passwd *pw)
+check_authkeys_file(FILE *f, char *file, struct sshkey *key, struct passwd *pw)
 {
         char line[SSH_MAX_PUBKEY_BYTES];
         int found_key = 0;
         u_long linenum = 0;
-        struct sshkey *found;
-
-        found_key = 0;
+        struct sshkey *found = NULL;
 
-        found = NULL;
         while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
                 char *cp, *key_options = NULL, *fp = NULL;
                 const char *reason = NULL;
@@ -780,8 +804,10 @@ check_authkeys_file(FILE *f, char *file, struct sshkey* key, struct passwd *pw)
                 if (found_key)
                         continue;
                 if (found != NULL)
-                        key_free(found);
-                found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
+                        sshkey_free(found);
+                found = sshkey_new(sshkey_is_cert(key) ? KEY_UNSPEC : key->type);
+                if (found == NULL)
+                        goto done;
                 auth_clear_options();
 
                 /* Skip leading whitespace, empty and comment lines. */
@@ -790,7 +816,7 @@ check_authkeys_file(FILE *f, char *file, struct sshkey* key, struct passwd *pw)
                 if (!*cp || *cp == '\n' || *cp == '#')
                         continue;
 
-                if (key_read(found, &cp) != 1) {
+                if (sshkey_read(found, &cp) != 0) {
                         /* no key?  check if there are options for this key */
                         int quoted = 0;
                         debug2("user_key_allowed: check options: '%s'", cp);
@@ -804,14 +830,14 @@ check_authkeys_file(FILE *f, char *file, struct sshkey* key, struct passwd *pw)
                         /* Skip remaining whitespace. */
                         for (; *cp == ' ' || *cp == '\t'; cp++)
                                 ;
-                        if (key_read(found, &cp) != 1) {
+                        if (sshkey_read(found, &cp) != 0) {
                                 debug2("user_key_allowed: advance: '%s'", cp);
                                 /* still no key?  advance to next line*/
                                 continue;
                         }
                 }
-                if (key_is_cert(key)) {
-                        if (!key_equal(found, key->cert->signature_key))
+                if (sshkey_is_cert(key)) {
+                        if (!sshkey_equal(found, key->cert->signature_key))
                                 continue;
                         if (auth_parse_options(pw, key_options, file,
                             linenum) != 1)
@@ -822,7 +848,7 @@ check_authkeys_file(FILE *f, char *file, struct sshkey* key, struct passwd *pw)
                             options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
                                 continue;
                         debug("matching CA found: file %s, line %lu, %s %s",
-                            file, linenum, key_type(found), fp);
+                            file, linenum, sshkey_type(found), fp);
                         /*
                          * If the user has specified a list of principals as
                          * a key option, then prefer that list to matching
@@ -839,7 +865,7 @@ check_authkeys_file(FILE *f, char *file, struct sshkey* key, struct passwd *pw)
                                 auth_debug_add("%s", reason);
                                 continue;
                         }
-                        if (key_cert_check_authority(key, 0, 0,
+                        if (sshkey_cert_check_authority(key, 0, 0,
                             authorized_principals == NULL ? pw->pw_name : NULL,
                             &reason) != 0)
                                 goto fail_reason;
@@ -848,11 +874,11 @@ check_authkeys_file(FILE *f, char *file, struct sshkey* key, struct passwd *pw)
                         verbose("Accepted certificate ID \"%s\" (serial %llu) "
                             "signed by %s CA %s via %s", key->cert->key_id,
                             (unsigned long long)key->cert->serial,
-                            key_type(found), fp, file);
+                            sshkey_type(found), fp, file);
                         free(fp);
                         found_key = 1;
                         break;
-                } else if (key_equal(found, key)) {
+                } else if (sshkey_equal(found, key)) {
                         if (auth_parse_options(pw, key_options, file,
                             linenum) != 1)
                                 continue;
@@ -862,14 +888,15 @@ check_authkeys_file(FILE *f, char *file, struct sshkey* key, struct passwd *pw)
                             options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
                                 continue;
                         debug("matching key found: file %s, line %lu %s %s",
-                            file, linenum, key_type(found), fp);
+                            file, linenum, sshkey_type(found), fp);
                         free(fp);
                         found_key = 1;
                         continue;
                 }
         }
+ done:
         if (found != NULL)
-                key_free(found);
+                sshkey_free(found);
         if (!found_key)
                 debug2("key not found");
         return found_key;
@@ -881,20 +908,20 @@ user_cert_trusted_ca(struct passwd *pw, struct sshkey *key)
 {
         char *ca_fp, *principals_file = NULL;
         const char *reason;
-        int ret = 0, found_principal = 0, use_authorized_principals;
+        int r, ret = 0, found_principal = 0, use_authorized_principals;
 
-        if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
+        if (!sshkey_is_cert(key) || options.trusted_user_ca_keys == NULL)
                 return 0;
 
         if ((ca_fp = sshkey_fingerprint(key->cert->signature_key,
             options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
                 return 0;
 
-        if (sshkey_in_file(key->cert->signature_key,
-            options.trusted_user_ca_keys, 1, 0) != 0) {
-                debug2("%s: CA %s %s is not listed in %s", __func__,
-                    key_type(key->cert->signature_key), ca_fp,
-                    options.trusted_user_ca_keys);
+        if ((r = sshkey_in_file(key->cert->signature_key,
+            options.trusted_user_ca_keys, 1, 0)) != 0) {
+                debug2("%s: CA %s %s is not listed in %s: %s", __func__,
+                    sshkey_type(key->cert->signature_key), ca_fp,
+                    options.trusted_user_ca_keys, ssh_err(r));
                 goto out;
         }
         /*
@@ -919,7 +946,7 @@ user_cert_trusted_ca(struct passwd *pw, struct sshkey *key)
                 auth_debug_add("%s", reason);
                 goto out;
         }
-        if (key_cert_check_authority(key, 0, 1,
+        if (sshkey_cert_check_authority(key, 0, 1,
             use_authorized_principals ? NULL : pw->pw_name, &reason) != 0)
                 goto fail_reason;
         if (auth_cert_options(key, pw, &reason) != 0)
@@ -928,7 +955,7 @@ user_cert_trusted_ca(struct passwd *pw, struct sshkey *key)
         verbose("Accepted certificate ID \"%s\" (serial %llu) signed by "
             "%s CA %s via %s", key->cert->key_id,
             (unsigned long long)key->cert->serial,
-            key_type(key->cert->signature_key), ca_fp,
+            sshkey_type(key->cert->signature_key), ca_fp,
             options.trusted_user_ca_keys);
         ret = 1;
 
@@ -1096,7 +1123,8 @@ user_key_allowed(struct passwd *pw, struct sshkey *key, int auth_attempt)
 
         if (auth_key_is_revoked(key))
                 return 0;
-        if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
+        if (sshkey_is_cert(key) &&
+            auth_key_is_revoked(key->cert->signature_key))
                 return 0;
 
         success = user_cert_trusted_ca(pw, key);
diff --git a/monitor.c b/monitor.c
index cd4089398..2dee9721d 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.168 2017/05/30 08:52:19 markus Exp $ */
+/* $OpenBSD: monitor.c,v 1.169 2017/05/30 14:10:53 markus Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -1330,25 +1330,25 @@ monitor_valid_hostbasedblob(u_char *data, u_int datalen, char *cuser,
 }
 
 int
-mm_answer_keyverify(int sock, Buffer *m)
+mm_answer_keyverify(int sock, struct sshbuf *m)
 {
         struct sshkey *key;
         u_char *signature, *data, *blob;
-        u_int signaturelen, datalen, bloblen;
-        int verified = 0;
-        int valid_data = 0;
+        size_t signaturelen, datalen, bloblen;
+        int r, ret, valid_data = 0, encoded_ret;
 
-        blob = buffer_get_string(m, &bloblen);
-        signature = buffer_get_string(m, &signaturelen);
-        data = buffer_get_string(m, &datalen);
+        if ((r = sshbuf_get_string(m, &blob, &bloblen)) != 0 ||
+            (r = sshbuf_get_string(m, &signature, &signaturelen)) != 0 ||
+            (r = sshbuf_get_string(m, &data, &datalen)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
         if (hostbased_cuser == NULL || hostbased_chost == NULL ||
           !monitor_allowed_key(blob, bloblen))
                 fatal("%s: bad key, not previously allowed", __func__);
 
-        key = key_from_blob(blob, bloblen);
-        if (key == NULL)
-                fatal("%s: bad public key blob", __func__);
+        /* XXX use sshkey_froms here; need to change key_blob, etc. */
+        if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
+                fatal("%s: bad public key blob: %s", __func__, ssh_err(r));
 
         switch (key_blobtype) {
         case MM_USERKEY:
@@ -1365,15 +1365,16 @@ mm_answer_keyverify(int sock, Buffer *m)
         if (!valid_data)
                 fatal("%s: bad signature data blob", __func__);
 
-        verified = key_verify(key, signature, signaturelen, data, datalen);
+        ret = sshkey_verify(key, signature, signaturelen, data, datalen,
+            active_state->compat);
         debug3("%s: key %p signature %s",
-            __func__, key, (verified == 1) ? "verified" : "unverified");
+            __func__, key, (ret == 0) ? "verified" : "unverified");
 
         /* If auth was successful then record key to ensure it isn't reused */
-        if (verified == 1 && key_blobtype == MM_USERKEY)
+        if (ret == 0 && key_blobtype == MM_USERKEY)
                 auth2_record_userkey(authctxt, key);
         else
-                key_free(key);
+                sshkey_free(key);
 
         free(blob);
         free(signature);
@@ -1383,11 +1384,15 @@ mm_answer_keyverify(int sock, Buffer *m)
 
         monitor_reset_key_state();
 
-        buffer_clear(m);
-        buffer_put_int(m, verified);
+        sshbuf_reset(m);
+
+        /* encode ret != 0 as positive integer, since we're sending u32 */
+        encoded_ret = (ret != 0);
+        if ((r = sshbuf_put_u32(m, encoded_ret)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
         mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
 
-        return (verified == 1);
+        return ret == 0;
 }
 
 static void
diff --git a/monitor_wrap.c b/monitor_wrap.c
index 0710a10b0..25f3e9678 100644
--- a/monitor_wrap.c
+++ b/monitor_wrap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.c,v 1.91 2017/05/30 08:52:19 markus Exp $ */
+/* $OpenBSD: monitor_wrap.c,v 1.92 2017/05/30 14:10:53 markus Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -436,13 +436,13 @@ mm_key_allowed(enum mm_keytype type, const char *user, const char *host,
  */
 
 int
-mm_key_verify(struct sshkey *key, u_char *sig, u_int siglen, u_char *data,
-    u_int datalen)
+mm_sshkey_verify(const struct sshkey *key, const u_char *sig, size_t siglen,
+    const u_char *data, size_t datalen, u_int compat)
 {
         Buffer m;
         u_char *blob;
         u_int len;
-        int verified = 0;
+        u_int encoded_ret = 0;
 
         debug3("%s entering", __func__);
 
@@ -461,11 +461,13 @@ mm_key_verify(struct sshkey *key, u_char *sig, u_int siglen, u_char *data,
         debug3("%s: waiting for MONITOR_ANS_KEYVERIFY", __func__);
         mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_KEYVERIFY, &m);
 
-        verified = buffer_get_int(&m);
+        encoded_ret = buffer_get_int(&m);
 
         buffer_free(&m);
 
-        return (verified);
+        if (encoded_ret != 0)
+                return SSH_ERR_SIGNATURE_INVALID;
+        return 0;
 }
 
 void
diff --git a/monitor_wrap.h b/monitor_wrap.h
index a1552d0c9..958cdbc92 100644
--- a/monitor_wrap.h
+++ b/monitor_wrap.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.h,v 1.33 2017/05/30 08:52:19 markus Exp $ */
+/* $OpenBSD: monitor_wrap.h,v 1.34 2017/05/30 14:10:53 markus Exp $ */
 
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
@@ -51,7 +51,8 @@ int mm_key_allowed(enum mm_keytype, const char *, const char *, struct sshkey *,
 int mm_user_key_allowed(struct passwd *, struct sshkey *, int);
 int mm_hostbased_key_allowed(struct passwd *, const char *,
     const char *, struct sshkey *);
-int mm_key_verify(struct sshkey *, u_char *, u_int, u_char *, u_int);
+int mm_sshkey_verify(const struct sshkey *, const u_char *, size_t,
+    const u_char *, size_t, u_int);
 
 #ifdef GSSAPI
 OM_uint32 mm_ssh_gssapi_server_ctx(Gssctxt **, gss_OID);