upstream: switch over to the new authorized_keys options API and

remove the legacy one.

Includes a fairly big refactor of auth2-pubkey.c to retain less state
between key file lines.

feedback and ok markus@

OpenBSD-Commit-ID: dece6cae0f47751b9892080eb13d6625599573df

1 files changed, 365 insertions, 167 deletions

diff --git a/auth2-pubkey.c b/auth2-pubkey.c
index 8fb7ffe71..8024b1d6a 100644
--- a/auth2-pubkey.c
+++ b/auth2-pubkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-pubkey.c,v 1.76 2018/02/07 22:52:45 dtucker Exp $ */
+/* $OpenBSD: auth2-pubkey.c,v 1.77 2018/03/03 03:15:51 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -88,6 +88,7 @@ static int
 userauth_pubkey(struct ssh *ssh)
 {
         Authctxt *authctxt = ssh->authctxt;
+        struct passwd *pw = authctxt->pw;
         struct sshbuf *b;
         struct sshkey *key = NULL;
         char *pkalg, *userstyle = NULL, *key_s = NULL, *ca_s = NULL;
@@ -95,6 +96,7 @@ userauth_pubkey(struct ssh *ssh)
         size_t blen, slen;
         int r, pktype;
         int authenticated = 0;
+        struct sshauthopt *authopts = NULL;
 
         if (!authctxt->valid) {
                 debug2("%s: disabled because of invalid user", __func__);
@@ -185,7 +187,7 @@ userauth_pubkey(struct ssh *ssh)
 
                 /* test for correct signature */
                 authenticated = 0;
-                if (PRIVSEP(user_key_allowed(authctxt->pw, key, 1)) &&
+                if (PRIVSEP(user_key_allowed(ssh, pw, key, 1, &authopts)) &&
                     PRIVSEP(sshkey_verify(key, sig, slen, sshbuf_ptr(b),
                     sshbuf_len(b), NULL, ssh->compat)) == 0) {
                         authenticated = 1;
@@ -210,7 +212,7 @@ userauth_pubkey(struct ssh *ssh)
                  * if a user is not allowed to login. is this an
                  * issue? -markus
                  */
-                if (PRIVSEP(user_key_allowed(authctxt->pw, key, 0))) {
+                if (PRIVSEP(user_key_allowed(ssh, pw, key, 0, NULL))) {
                         if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_PK_OK))
                             != 0 ||
                             (r = sshpkt_put_cstring(ssh, pkalg)) != 0 ||
@@ -221,10 +223,14 @@ userauth_pubkey(struct ssh *ssh)
                         authctxt->postponed = 1;
                 }
         }
-        if (authenticated != 1)
-                auth_clear_options();
 done:
+        if (authenticated == 1 && auth_activate_options(ssh, authopts) != 0) {
+                debug("%s: key options inconsistent with existing", __func__);
+                authenticated = 0;
+        }
         debug2("%s: authenticated %d pkalg %s", __func__, authenticated, pkalg);
+
+        sshauthopt_free(authopts);
         sshkey_free(key);
         free(userstyle);
         free(pkalg);
@@ -254,18 +260,77 @@ match_principals_option(const char *principal_list, struct sshkey_cert *cert)
         return 0;
 }
 
+/*
+ * Process a single authorized_principals format line. Returns 0 and sets
+ * authoptsp is principal is authorised, -1 otherwise. "loc" is used as a
+ * log preamble for file/line information.
+ */
+static int
+check_principals_line(struct ssh *ssh, char *cp, const struct sshkey_cert *cert,
+    const char *loc, struct sshauthopt **authoptsp)
+{
+        u_int i, found = 0;
+        char *ep, *line_opts;
+        const char *reason = NULL;
+        struct sshauthopt *opts = NULL;
+
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
+
+        /* Trim trailing whitespace. */
+        ep = cp + strlen(cp) - 1;
+        while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
+                *ep-- = '\0';
+
+        /*
+         * If the line has internal whitespace then assume it has
+         * key options.
+         */
+        line_opts = NULL;
+        if ((ep = strrchr(cp, ' ')) != NULL ||
+            (ep = strrchr(cp, '\t')) != NULL) {
+                for (; *ep == ' ' || *ep == '\t'; ep++)
+                        ;
+                line_opts = cp;
+                cp = ep;
+        }
+        if ((opts = sshauthopt_parse(line_opts, &reason)) == NULL) {
+                debug("%s: bad principals options: %s", loc, reason);
+                auth_debug_add("%s: bad principals options: %s", loc, reason);
+                return -1;
+        }
+        /* Check principals in cert against those on line */
+        for (i = 0; i < cert->nprincipals; i++) {
+                if (strcmp(cp, cert->principals[i]) != 0)
+                        continue;
+                debug3("%s: matched principal \"%.100s\"",
+                    loc, cert->principals[i]);
+                found = 1;
+        }
+        if (found && authoptsp != NULL) {
+                *authoptsp = opts;
+                opts = NULL;
+        }
+        sshauthopt_free(opts);
+        return found ? 0 : -1;
+}
+
 static int
-process_principals(FILE *f, const char *file, struct passwd *pw,
-    const struct sshkey_cert *cert)
+process_principals(struct ssh *ssh, FILE *f, const char *file,
+    const struct sshkey_cert *cert, struct sshauthopt **authoptsp)
 {
-        char line[SSH_MAX_PUBKEY_BYTES], *cp, *ep, *line_opts;
+        char loc[256], line[SSH_MAX_PUBKEY_BYTES], *cp, *ep;
         u_long linenum = 0;
-        u_int i, found_principal = 0;
+        u_int found_principal = 0;
+
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
 
         while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
                 /* Always consume entire input */
                 if (found_principal)
                         continue;
+
                 /* Skip leading whitespace. */
                 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
                         ;
@@ -274,50 +339,33 @@ process_principals(FILE *f, const char *file, struct passwd *pw,
                         *ep = '\0';
                 if (!*cp || *cp == '\n')
                         continue;
-                /* Trim trailing whitespace. */
-                ep = cp + strlen(cp) - 1;
-                while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
-                        *ep-- = '\0';
-                /*
-                 * If the line has internal whitespace then assume it has
-                 * key options.
-                 */
-                line_opts = NULL;
-                if ((ep = strrchr(cp, ' ')) != NULL ||
-                    (ep = strrchr(cp, '\t')) != NULL) {
-                        for (; *ep == ' ' || *ep == '\t'; ep++)
-                                ;
-                        line_opts = cp;
-                        cp = ep;
-                }
-                for (i = 0; i < cert->nprincipals; i++) {
-                        if (strcmp(cp, cert->principals[i]) == 0) {
-                                debug3("%s:%lu: matched principal \"%.100s\"",
-                                    file, linenum, cert->principals[i]);
-                                if (auth_parse_options(pw, line_opts,
-                                    file, linenum) != 1)
-                                        continue;
-                                found_principal = 1;
-                                continue;
-                        }
-                }
+
+                snprintf(loc, sizeof(loc), "%.200s:%lu", file, linenum);
+                if (check_principals_line(ssh, cp, cert, loc, authoptsp) == 0)
+                        found_principal = 1;
         }
         return found_principal;
 }
 
+/* XXX remove pw args here and elsewhere once ssh->authctxt is guaranteed */
+
 static int
-match_principals_file(char *file, struct passwd *pw, struct sshkey_cert *cert)
+match_principals_file(struct ssh *ssh, struct passwd *pw, char *file,
+    struct sshkey_cert *cert, struct sshauthopt **authoptsp)
 {
         FILE *f;
         int success;
 
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
+
         temporarily_use_uid(pw);
         debug("trying authorized principals file %s", file);
         if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
                 restore_uid();
                 return 0;
         }
-        success = process_principals(f, file, pw, cert);
+        success = process_principals(ssh, f, file, cert, authoptsp);
         fclose(f);
         restore_uid();
         return success;
@@ -328,12 +376,13 @@ match_principals_file(char *file, struct passwd *pw, struct sshkey_cert *cert)
  * returns 1 if the principal is allowed or 0 otherwise.
  */
 static int
-match_principals_command(struct passwd *user_pw, const struct sshkey *key)
+match_principals_command(struct ssh *ssh, struct passwd *user_pw,
+    const struct sshkey *key, struct sshauthopt **authoptsp)
 {
+        struct passwd *runas_pw = NULL;
         const struct sshkey_cert *cert = key->cert;
         FILE *f = NULL;
         int r, ok, found_principal = 0;
-        struct passwd *pw;
         int i, ac = 0, uid_swapped = 0;
         pid_t pid;
         char *tmp, *username = NULL, *command = NULL, **av = NULL;
@@ -341,6 +390,8 @@ match_principals_command(struct passwd *user_pw, const struct sshkey *key)
         char serial_s[16];
         void (*osigchld)(int);
 
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
         if (options.authorized_principals_command == NULL)
                 return 0;
         if (options.authorized_principals_command_user == NULL) {
@@ -358,8 +409,8 @@ match_principals_command(struct passwd *user_pw, const struct sshkey *key)
         /* Prepare and verify the user for the command */
         username = percent_expand(options.authorized_principals_command_user,
             "u", user_pw->pw_name, (char *)NULL);
-        pw = getpwnam(username);
-        if (pw == NULL) {
+        runas_pw = getpwnam(username);
+        if (runas_pw == NULL) {
                 error("AuthorizedPrincipalsCommandUser \"%s\" not found: %s",
                     username, strerror(errno));
                 goto out;
@@ -417,15 +468,15 @@ match_principals_command(struct passwd *user_pw, const struct sshkey *key)
         /* Prepare a printable command for logs, etc. */
         command = argv_assemble(ac, av);
 
-        if ((pid = subprocess("AuthorizedPrincipalsCommand", pw, command,
+        if ((pid = subprocess("AuthorizedPrincipalsCommand", runas_pw, command,
             ac, av, &f,
             SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
                 goto out;
 
         uid_swapped = 1;
-        temporarily_use_uid(pw);
+        temporarily_use_uid(runas_pw);
 
-        ok = process_principals(f, "(command)", pw, cert);
+        ok = process_principals(ssh, f, "(command)", cert, authoptsp);
 
         fclose(f);
         f = NULL;
@@ -452,130 +503,225 @@ match_principals_command(struct passwd *user_pw, const struct sshkey *key)
         free(keytext);
         return found_principal;
 }
+
+static void
+skip_space(char **cpp)
+{
+        char *cp;
+
+        for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
+                ;
+        *cpp = cp;
+}
+
+/*
+ * Advanced *cpp past the end of key options, defined as the first unquoted
+ * whitespace character. Returns 0 on success or -1 on failure (e.g.
+ * unterminated quotes).
+ */
+static int
+advance_past_options(char **cpp)
+{
+        char *cp = *cpp;
+        int quoted = 0;
+
+        for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
+                if (*cp == '\\' && cp[1] == '"')
+                        cp++;   /* Skip both */
+                else if (*cp == '"')
+                        quoted = !quoted;
+        }
+        *cpp = cp;
+        /* return failure for unterminated quotes */
+        return (*cp == '\0' && quoted) ? -1 : 0;
+}
+
+/*
+ * Check a single line of an authorized_keys-format file. Returns 0 if key
+ * matches, -1 otherwise. Will return key/cert options via *authoptsp
+ * on success. "loc" is used as file/line location in log messages.
+ */
+static int
+check_authkey_line(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
+    char *cp, const char *loc, struct sshauthopt **authoptsp)
+{
+        int want_keytype = sshkey_is_cert(key) ? KEY_UNSPEC : key->type;
+        struct sshkey *found = NULL;
+        struct sshauthopt *keyopts = NULL, *certopts = NULL, *finalopts = NULL;
+        char *key_options = NULL, *fp = NULL;
+        const char *reason = NULL;
+        int ret = -1;
+
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
+
+        if ((found = sshkey_new(want_keytype)) == NULL) {
+                debug3("%s: keytype %d failed", __func__, want_keytype);
+                goto out;
+        }
+
+        /* XXX djm: peek at key type in line and skip if unwanted */
+
+        if (sshkey_read(found, &cp) != 0) {
+                /* no key?  check for options */
+                debug2("%s: check options: '%s'", loc, cp);
+                key_options = cp;
+                if (advance_past_options(&cp) != 0) {
+                        reason = "invalid key option string";
+                        goto fail_reason;
+                }
+                skip_space(&cp);
+                if (sshkey_read(found, &cp) != 0) {
+                        /* still no key?  advance to next line*/
+                        debug2("%s: advance: '%s'", loc, cp);
+                        goto out;
+                }
+        }
+        /* Parse key options now; we need to know if this is a CA key */
+        if ((keyopts = sshauthopt_parse(key_options, &reason)) == NULL) {
+                debug("%s: bad key options: %s", loc, reason);
+                auth_debug_add("%s: bad key options: %s", loc, reason);
+                goto out;
+        }
+        /* Ignore keys that don't match or incorrectly marked as CAs */
+        if (sshkey_is_cert(key)) {
+                /* Certificate; check signature key against CA */
+                if (!sshkey_equal(found, key->cert->signature_key) ||
+                    !keyopts->cert_authority)
+                        goto out;
+        } else {
+                /* Plain key: check it against key found in file */
+                if (!sshkey_equal(found, key) || keyopts->cert_authority)
+                        goto out;
+        }
+
+        /* We have a candidate key, perform authorisation checks */
+        if ((fp = sshkey_fingerprint(found,
+            options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
+                fatal("%s: fingerprint failed", __func__);
+
+        debug("%s: matching %s found: %s %s", loc,
+            sshkey_is_cert(key) ? "CA" : "key", sshkey_type(found), fp);
+
+        if (auth_authorise_keyopts(ssh, pw, keyopts,
+            sshkey_is_cert(key), loc) != 0) {
+                reason = "Refused by key options";
+                goto fail_reason;
+        }
+        /* That's all we need for plain keys. */
+        if (!sshkey_is_cert(key)) {
+                verbose("Accepted key %s %s found at %s",
+                    sshkey_type(found), fp, loc);
+                finalopts = keyopts;
+                keyopts = NULL;
+                goto success;
+        }
+
+        /*
+         * Additional authorisation for certificates.
+         */
+
+        /* Parse and check options present in certificate */
+        if ((certopts = sshauthopt_from_cert(key)) == NULL) {
+                reason = "Invalid certificate options";
+                goto fail_reason;
+        }
+        if (auth_authorise_keyopts(ssh, pw, certopts, 0, loc) != 0) {
+                reason = "Refused by certificate options";
+                goto fail_reason;
+        }
+        if ((finalopts = sshauthopt_merge(keyopts, certopts, &reason)) == NULL)
+                goto fail_reason;
+
+        /*
+         * If the user has specified a list of principals as
+         * a key option, then prefer that list to matching
+         * their username in the certificate principals list.
+         */
+        if (keyopts->cert_principals != NULL &&
+            !match_principals_option(keyopts->cert_principals, key->cert)) {
+                reason = "Certificate does not contain an authorized principal";
+                goto fail_reason;
+        }
+        if (sshkey_cert_check_authority(key, 0, 0,
+           keyopts->cert_principals == NULL ? pw->pw_name : NULL, &reason) != 0)
+                goto fail_reason;
+
+        verbose("Accepted certificate ID \"%s\" (serial %llu) "
+            "signed by CA %s %s found at %s",
+            key->cert->key_id,
+            (unsigned long long)key->cert->serial,
+            sshkey_type(found), fp, loc);
+
+ success:
+        if (finalopts == NULL)
+                fatal("%s: internal error: missing options", __func__);
+        if (authoptsp != NULL) {
+                *authoptsp = finalopts;
+                finalopts = NULL;
+        }
+        /* success */
+        ret = 0;
+        goto out;
+
+ fail_reason:
+        error("%s", reason);
+        auth_debug_add("%s", reason);
+ out:
+        free(fp);
+        sshauthopt_free(keyopts);
+        sshauthopt_free(certopts);
+        sshauthopt_free(finalopts);
+        sshkey_free(found);
+        return ret;
+}
+
 /*
  * Checks whether key is allowed in authorized_keys-format file,
  * 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(struct ssh *ssh, struct passwd *pw, FILE *f,
+    char *file, struct sshkey *key, struct sshauthopt **authoptsp)
 {
-        char line[SSH_MAX_PUBKEY_BYTES];
+        char *cp, line[SSH_MAX_PUBKEY_BYTES], loc[256];
         int found_key = 0;
         u_long linenum = 0;
-        struct sshkey *found = NULL;
 
-        while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
-                char *cp, *key_options = NULL, *fp = NULL;
-                const char *reason = NULL;
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
 
+        while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
                 /* Always consume entire file */
                 if (found_key)
                         continue;
-                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. */
-                for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
-                        ;
+                cp = line;
+                skip_space(&cp);
                 if (!*cp || *cp == '\n' || *cp == '#')
                         continue;
-
-                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);
-                        key_options = cp;
-                        for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
-                                if (*cp == '\\' && cp[1] == '"')
-                                        cp++;   /* Skip both */
-                                else if (*cp == '"')
-                                        quoted = !quoted;
-                        }
-                        /* Skip remaining whitespace. */
-                        for (; *cp == ' ' || *cp == '\t'; cp++)
-                                ;
-                        if (sshkey_read(found, &cp) != 0) {
-                                debug2("user_key_allowed: advance: '%s'", cp);
-                                /* still no key?  advance to next line*/
-                                continue;
-                        }
-                }
-                if (sshkey_is_cert(key)) {
-                        if (!sshkey_equal(found, key->cert->signature_key))
-                                continue;
-                        if (auth_parse_options(pw, key_options, file,
-                            linenum) != 1)
-                                continue;
-                        if (!key_is_cert_authority)
-                                continue;
-                        if ((fp = sshkey_fingerprint(found,
-                            options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
-                                continue;
-                        debug("matching CA found: file %s, line %lu, %s %s",
-                            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
-                         * their username in the certificate principals list.
-                         */
-                        if (authorized_principals != NULL &&
-                            !match_principals_option(authorized_principals,
-                            key->cert)) {
-                                reason = "Certificate does not contain an "
-                                    "authorized principal";
- fail_reason:
-                                free(fp);
-                                error("%s", reason);
-                                auth_debug_add("%s", reason);
-                                continue;
-                        }
-                        if (sshkey_cert_check_authority(key, 0, 0,
-                            authorized_principals == NULL ? pw->pw_name : NULL,
-                            &reason) != 0)
-                                goto fail_reason;
-                        if (auth_cert_options(key, pw, &reason) != 0)
-                                goto fail_reason;
-                        verbose("Accepted certificate ID \"%s\" (serial %llu) "
-                            "signed by %s CA %s via %s", key->cert->key_id,
-                            (unsigned long long)key->cert->serial,
-                            sshkey_type(found), fp, file);
-                        free(fp);
-                        found_key = 1;
-                        break;
-                } else if (sshkey_equal(found, key)) {
-                        if (auth_parse_options(pw, key_options, file,
-                            linenum) != 1)
-                                continue;
-                        if (key_is_cert_authority)
-                                continue;
-                        if ((fp = sshkey_fingerprint(found,
-                            options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
-                                continue;
-                        debug("matching key found: file %s, line %lu %s %s",
-                            file, linenum, sshkey_type(found), fp);
-                        free(fp);
+                snprintf(loc, sizeof(loc), "%.200s:%lu", file, linenum);
+                if (check_authkey_line(ssh, pw, key, cp, loc, authoptsp) == 0)
                         found_key = 1;
-                        continue;
-                }
         }
- done:
-        sshkey_free(found);
-        if (!found_key)
-                debug2("key not found");
         return found_key;
 }
 
 /* Authenticate a certificate key against TrustedUserCAKeys */
 static int
-user_cert_trusted_ca(struct passwd *pw, struct sshkey *key)
+user_cert_trusted_ca(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
+    struct sshauthopt **authoptsp)
 {
         char *ca_fp, *principals_file = NULL;
         const char *reason;
+        struct sshauthopt *principals_opts = NULL, *cert_opts = NULL;
+        struct sshauthopt *final_opts = NULL;
         int r, ret = 0, found_principal = 0, use_authorized_principals;
 
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
+
         if (!sshkey_is_cert(key) || options.trusted_user_ca_keys == NULL)
                 return 0;
 
@@ -596,36 +742,69 @@ user_cert_trusted_ca(struct passwd *pw, struct sshkey *key)
          * against the username.
          */
         if ((principals_file = authorized_principals_file(pw)) != NULL) {
-                if (match_principals_file(principals_file, pw, key->cert))
+                if (match_principals_file(ssh, pw, principals_file,
+                    key->cert, &principals_opts))
                         found_principal = 1;
         }
         /* Try querying command if specified */
-        if (!found_principal && match_principals_command(pw, key))
+        if (!found_principal && match_principals_command(ssh, pw, key,
+            &principals_opts))
                 found_principal = 1;
         /* If principals file or command is specified, then require a match */
         use_authorized_principals = principals_file != NULL ||
             options.authorized_principals_command != NULL;
         if (!found_principal && use_authorized_principals) {
                 reason = "Certificate does not contain an authorized principal";
- fail_reason:
-                error("%s", reason);
-                auth_debug_add("%s", reason);
-                goto out;
+                goto fail_reason;
         }
+        if (use_authorized_principals && principals_opts == NULL)
+                fatal("%s: internal error: missing principals_opts", __func__);
         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)
+
+        /* Check authority from options in key and from principals file/cmd */
+        if ((cert_opts = sshauthopt_from_cert(key)) == NULL) {
+                reason = "Invalid certificate options";
+                goto fail_reason;
+        }
+        if (auth_authorise_keyopts(ssh, pw, cert_opts, 0, "cert") != 0) {
+                reason = "Refused by certificate options";
                 goto fail_reason;
+        }
+        if (principals_opts == NULL) {
+                final_opts = cert_opts;
+                cert_opts = NULL;
+        } else {
+                if (auth_authorise_keyopts(ssh, pw, principals_opts, 0,
+                    "principals") != 0) {
+                        reason = "Refused by certificate principals options";
+                        goto fail_reason;
+                }
+                if ((final_opts = sshauthopt_merge(principals_opts,
+                    cert_opts, &reason)) == NULL) {
+ fail_reason:
+                        error("%s", reason);
+                        auth_debug_add("%s", reason);
+                        goto out;
+                }
+        }
 
+        /* Success */
         verbose("Accepted certificate ID \"%s\" (serial %llu) signed by "
             "%s CA %s via %s", key->cert->key_id,
             (unsigned long long)key->cert->serial,
             sshkey_type(key->cert->signature_key), ca_fp,
             options.trusted_user_ca_keys);
+        if (authoptsp != NULL) {
+                *authoptsp = final_opts;
+                final_opts = NULL;
+        }
         ret = 1;
-
  out:
+        sshauthopt_free(principals_opts);
+        sshauthopt_free(cert_opts);
+        sshauthopt_free(final_opts);
         free(principals_file);
         free(ca_fp);
         return ret;
@@ -636,17 +815,22 @@ user_cert_trusted_ca(struct passwd *pw, struct sshkey *key)
  * returns 1 if the key is allowed or 0 otherwise.
  */
 static int
-user_key_allowed2(struct passwd *pw, struct sshkey *key, char *file)
+user_key_allowed2(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
+    char *file, struct sshauthopt **authoptsp)
 {
         FILE *f;
         int found_key = 0;
 
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
+
         /* Temporarily use the user's uid. */
         temporarily_use_uid(pw);
 
         debug("trying public key file %s", file);
         if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
-                found_key = check_authkeys_file(f, file, key, pw);
+                found_key = check_authkeys_file(ssh, pw, f, file,
+                    key, authoptsp);
                 fclose(f);
         }
 
@@ -659,17 +843,20 @@ user_key_allowed2(struct passwd *pw, struct sshkey *key, char *file)
  * returns 1 if the key is allowed or 0 otherwise.
  */
 static int
-user_key_command_allowed2(struct passwd *user_pw, struct sshkey *key)
+user_key_command_allowed2(struct ssh *ssh, struct passwd *user_pw,
+    struct sshkey *key, struct sshauthopt **authoptsp)
 {
+        struct passwd *runas_pw = NULL;
         FILE *f = NULL;
         int r, ok, found_key = 0;
-        struct passwd *pw;
         int i, uid_swapped = 0, ac = 0;
         pid_t pid;
         char *username = NULL, *key_fp = NULL, *keytext = NULL;
         char *tmp, *command = NULL, **av = NULL;
         void (*osigchld)(int);
 
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
         if (options.authorized_keys_command == NULL)
                 return 0;
         if (options.authorized_keys_command_user == NULL) {
@@ -686,8 +873,8 @@ user_key_command_allowed2(struct passwd *user_pw, struct sshkey *key)
         /* Prepare and verify the user for the command */
         username = percent_expand(options.authorized_keys_command_user,
             "u", user_pw->pw_name, (char *)NULL);
-        pw = getpwnam(username);
-        if (pw == NULL) {
+        runas_pw = getpwnam(username);
+        if (runas_pw == NULL) {
                 error("AuthorizedKeysCommandUser \"%s\" not found: %s",
                     username, strerror(errno));
                 goto out;
@@ -745,15 +932,16 @@ user_key_command_allowed2(struct passwd *user_pw, struct sshkey *key)
                 xasprintf(&command, "%s %s", av[0], av[1]);
         }
 
-        if ((pid = subprocess("AuthorizedKeysCommand", pw, command,
+        if ((pid = subprocess("AuthorizedKeysCommand", runas_pw, command,
             ac, av, &f,
             SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
                 goto out;
 
         uid_swapped = 1;
-        temporarily_use_uid(pw);
+        temporarily_use_uid(runas_pw);
 
-        ok = check_authkeys_file(f, options.authorized_keys_command, key, pw);
+        ok = check_authkeys_file(ssh, user_pw, f,
+            options.authorized_keys_command, key, authoptsp);
 
         fclose(f);
         f = NULL;
@@ -783,10 +971,14 @@ user_key_command_allowed2(struct passwd *user_pw, struct sshkey *key)
  * Check whether key authenticates and authorises the user.
  */
 int
-user_key_allowed(struct passwd *pw, struct sshkey *key, int auth_attempt)
+user_key_allowed(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
+    int auth_attempt, struct sshauthopt **authoptsp)
 {
         u_int success, i;
         char *file;
+        struct sshauthopt *opts = NULL;
+        if (authoptsp != NULL)
+                *authoptsp = NULL;
 
         if (auth_key_is_revoked(key))
                 return 0;
@@ -794,25 +986,31 @@ user_key_allowed(struct passwd *pw, struct sshkey *key, int auth_attempt)
             auth_key_is_revoked(key->cert->signature_key))
                 return 0;
 
-        success = user_cert_trusted_ca(pw, key);
-        if (success)
-                return success;
+        if ((success = user_cert_trusted_ca(ssh, pw, key, &opts)) != 0)
+                goto out;
+        sshauthopt_free(opts);
+        opts = NULL;
 
-        success = user_key_command_allowed2(pw, key);
-        if (success > 0)
-                return success;
+        if ((success = user_key_command_allowed2(ssh, pw, key, &opts)) != 0)
+                goto out;
+        sshauthopt_free(opts);
+        opts = NULL;
 
         for (i = 0; !success && i < options.num_authkeys_files; i++) {
-
                 if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
                         continue;
                 file = expand_authorized_keys(
                     options.authorized_keys_files[i], pw);
-
-                success = user_key_allowed2(pw, key, file);
+                success = user_key_allowed2(ssh, pw, key, file, &opts);
                 free(file);
         }
 
+ out:
+        if (success && authoptsp != NULL) {
+                *authoptsp = opts;
+                opts = NULL;
+        }
+        sshauthopt_free(opts);
         return success;
 }