upstream commit

allow ssh to use certificates accompanied by a private
key file but no corresponding plain *.pub public key. bz#2617 based on patch
from Adam Eijdenberg; ok dtucker@ markus@

Upstream-ID: 295668dca2c39505281577217583ddd2bd4b00b9

1 files changed, 52 insertions, 15 deletions

diff --git a/sshconnect2.c b/sshconnect2.c
index 2abb86679..f8a54beea 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect2.c,v 1.254 2017/02/03 02:56:00 dtucker Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.255 2017/03/11 23:40:26 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
@@ -996,11 +996,11 @@ input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 }
 
 static const char *
-identity_sign_encode(struct identity *id)
+key_sign_encode(const struct sshkey *key)
 {
         struct ssh *ssh = active_state;
 
-        if (id->key->type == KEY_RSA) {
+        if (key->type == KEY_RSA) {
                 switch (ssh->kex->rsa_sha2) {
                 case 256:
                         return "rsa-sha2-256";
@@ -1008,7 +1008,7 @@ identity_sign_encode(struct identity *id)
                         return "rsa-sha2-512";
                 }
         }
-        return key_ssh_name(id->key);
+        return key_ssh_name(key);
 }
 
 static int
@@ -1017,31 +1017,50 @@ identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
 {
         Key *prv;
         int ret;
-        const char *alg;
-
-        alg = identity_sign_encode(id);
 
         /* the agent supports this key */
-        if (id->agent_fd != -1)
+        if (id->key != NULL && id->agent_fd != -1)
                 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
-                    data, datalen, alg, compat);
+                    data, datalen, key_sign_encode(id->key), compat);
 
         /*
          * we have already loaded the private key or
          * the private key is stored in external hardware
          */
-        if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))
-                return (sshkey_sign(id->key, sigp, lenp, data, datalen, alg,
-                    compat));
+        if (id->key != NULL &&
+            (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)))
+                return (sshkey_sign(id->key, sigp, lenp, data, datalen,
+                    key_sign_encode(id->key), compat));
+
         /* load the private key from the file */
         if ((prv = load_identity_file(id)) == NULL)
                 return SSH_ERR_KEY_NOT_FOUND;
-        ret = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat);
+        ret = sshkey_sign(prv, sigp, lenp, data, datalen,
+            key_sign_encode(prv), compat);
         sshkey_free(prv);
         return (ret);
 }
 
 static int
+id_filename_matches(Identity *id, Identity *private_id)
+{
+        const char *suffixes[] = { ".pub", "-cert.pub", NULL };
+        size_t len = strlen(id->filename), plen = strlen(private_id->filename);
+        size_t i, slen;
+
+        if (strcmp(id->filename, private_id->filename) == 0)
+                return 1;
+        for (i = 0; suffixes[i]; i++) {
+                slen = strlen(suffixes[i]);
+                if (len > slen && plen == len - slen &&
+                    strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
+                    memcmp(id->filename, private_id->filename, plen) == 0)
+                        return 1;
+        }
+        return 0;
+}
+
+static int
 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
 {
         Buffer b;
@@ -1083,7 +1102,7 @@ sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
         } else {
                 buffer_put_cstring(&b, authctxt->method->name);
                 buffer_put_char(&b, have_sig);
-                buffer_put_cstring(&b, identity_sign_encode(id));
+                buffer_put_cstring(&b, key_sign_encode(id->key));
         }
         buffer_put_string(&b, blob, bloblen);
 
@@ -1103,6 +1122,24 @@ sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
                                 break;
                         }
                 }
+                /*
+                 * Exact key matches are preferred, but also allow
+                 * filename matches for non-PKCS#11/agent keys that
+                 * didn't load public keys. This supports the case
+                 * of keeping just a private key file and public
+                 * certificate on disk.
+                 */
+                if (!matched && !id->isprivate && id->agent_fd == -1 &&
+                    (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
+                        TAILQ_FOREACH(private_id, &authctxt->keys, next) {
+                                if (private_id->key == NULL &&
+                                    id_filename_matches(id, private_id)) {
+                                        id = private_id;
+                                        matched = 1;
+                                        break;
+                                }
+                        }
+                }
                 if (matched) {
                         debug2("%s: using private key \"%s\"%s for "
                             "certificate", __func__, id->filename,
@@ -1181,7 +1218,7 @@ send_pubkey_test(Authctxt *authctxt, Identity *id)
         packet_put_cstring(authctxt->method->name);
         packet_put_char(have_sig);
         if (!(datafellows & SSH_BUG_PKAUTH))
-                packet_put_cstring(identity_sign_encode(id));
+                packet_put_cstring(key_sign_encode(id->key));
         packet_put_string(blob, bloblen);
         free(blob);
         packet_send();