Adding upstream version 1:9.2p1.upstream/1%9.2p1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 266 insertions, 0 deletions

diff --git a/auth2-hostbased.c b/auth2-hostbased.c
new file mode 100644
index 0000000..6b517db
--- /dev/null
+++ b/auth2-hostbased.c
@@ -0,0 +1,266 @@
+/* $OpenBSD: auth2-hostbased.c,v 1.50 2022/09/17 10:34:29 djm Exp $ */
+/*
+ * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+
+#include <stdlib.h>
+#include <pwd.h>
+#include <string.h>
+#include <stdarg.h>
+
+#include "xmalloc.h"
+#include "ssh2.h"
+#include "packet.h"
+#include "kex.h"
+#include "sshbuf.h"
+#include "log.h"
+#include "misc.h"
+#include "servconf.h"
+#include "compat.h"
+#include "sshkey.h"
+#include "hostfile.h"
+#include "auth.h"
+#include "canohost.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+#include "monitor_wrap.h"
+#include "pathnames.h"
+#include "ssherr.h"
+#include "match.h"
+
+/* import */
+extern ServerOptions options;
+
+static int
+userauth_hostbased(struct ssh *ssh, const char *method)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	struct sshbuf *b;
+	struct sshkey *key = NULL;
+	char *pkalg, *cuser, *chost;
+	u_char *pkblob, *sig;
+	size_t alen, blen, slen;
+	int r, pktype, authenticated = 0;
+
+	/* XXX use sshkey_froms() */
+	if ((r = sshpkt_get_cstring(ssh, &pkalg, &alen)) != 0 ||
+	    (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &chost, NULL)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &cuser, NULL)) != 0 ||
+	    (r = sshpkt_get_string(ssh, &sig, &slen)) != 0)
+		fatal_fr(r, "parse packet");
+
+	debug_f("cuser %s chost %s pkalg %s slen %zu",
+	    cuser, chost, pkalg, slen);
+#ifdef DEBUG_PK
+	debug("signature:");
+	sshbuf_dump_data(sig, slen, stderr);
+#endif
+	pktype = sshkey_type_from_name(pkalg);
+	if (pktype == KEY_UNSPEC) {
+		/* this is perfectly legal */
+		logit_f("unsupported public key algorithm: %s",
+		    pkalg);
+		goto done;
+	}
+	if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
+		error_fr(r, "key_from_blob");
+		goto done;
+	}
+	if (key == NULL) {
+		error_f("cannot decode key: %s", pkalg);
+		goto done;
+	}
+	if (key->type != pktype) {
+		error_f("type mismatch for decoded key "
+		    "(received %d, expected %d)", key->type, pktype);
+		goto done;
+	}
+	if (sshkey_type_plain(key->type) == KEY_RSA &&
+	    (ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
+		error("Refusing RSA key because peer uses unsafe "
+		    "signature format");
+		goto done;
+	}
+	if (match_pattern_list(pkalg, options.hostbased_accepted_algos, 0) != 1) {
+		logit_f("signature algorithm %s not in "
+		    "HostbasedAcceptedAlgorithms", pkalg);
+		goto done;
+	}
+	if ((r = sshkey_check_cert_sigtype(key,
+	    options.ca_sign_algorithms)) != 0) {
+		logit_fr(r, "certificate signature algorithm %s",
+		    (key->cert == NULL || key->cert->signature_type == NULL) ?
+		    "(null)" : key->cert->signature_type);
+		goto done;
+	}
+	if ((r = sshkey_check_rsa_length(key,
+	    options.required_rsa_size)) != 0) {
+		logit_r(r, "refusing %s key", sshkey_type(key));
+		goto done;
+	}
+
+	if (!authctxt->valid || authctxt->user == NULL) {
+		debug2_f("disabled because of invalid user");
+		goto done;
+	}
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new failed");
+	/* reconstruct packet */
+	if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 ||
+	    (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshbuf_put_cstring(b, authctxt->user)) != 0 ||
+	    (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
+	    (r = sshbuf_put_cstring(b, method)) != 0 ||
+	    (r = sshbuf_put_string(b, pkalg, alen)) != 0 ||
+	    (r = sshbuf_put_string(b, pkblob, blen)) != 0 ||
+	    (r = sshbuf_put_cstring(b, chost)) != 0 ||
+	    (r = sshbuf_put_cstring(b, cuser)) != 0)
+		fatal_fr(r, "reconstruct packet");
+#ifdef DEBUG_PK
+	sshbuf_dump(b, stderr);
+#endif
+
+	auth2_record_info(authctxt,
+	    "client user \"%.100s\", client host \"%.100s\"", cuser, chost);
+
+	/* test for allowed key and correct signature */
+	authenticated = 0;
+	if (PRIVSEP(hostbased_key_allowed(ssh, authctxt->pw, cuser,
+	    chost, key)) &&
+	    PRIVSEP(sshkey_verify(key, sig, slen,
+	    sshbuf_ptr(b), sshbuf_len(b), pkalg, ssh->compat, NULL)) == 0)
+		authenticated = 1;
+
+	auth2_record_key(authctxt, authenticated, key);
+	sshbuf_free(b);
+done:
+	debug2_f("authenticated %d", authenticated);
+	sshkey_free(key);
+	free(pkalg);
+	free(pkblob);
+	free(cuser);
+	free(chost);
+	free(sig);
+	return authenticated;
+}
+
+/* return 1 if given hostkey is allowed */
+int
+hostbased_key_allowed(struct ssh *ssh, struct passwd *pw,
+    const char *cuser, char *chost, struct sshkey *key)
+{
+	const char *resolvedname, *ipaddr, *lookup, *reason;
+	HostStatus host_status;
+	int len;
+	char *fp;
+
+	if (auth_key_is_revoked(key))
+		return 0;
+
+	resolvedname = auth_get_canonical_hostname(ssh, options.use_dns);
+	ipaddr = ssh_remote_ipaddr(ssh);
+
+	debug2_f("chost %s resolvedname %s ipaddr %s",
+	    chost, resolvedname, ipaddr);
+
+	if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
+		debug2("stripping trailing dot from chost %s", chost);
+		chost[len - 1] = '\0';
+	}
+
+	if (options.hostbased_uses_name_from_packet_only) {
+		if (auth_rhosts2(pw, cuser, chost, chost) == 0) {
+			debug2_f("auth_rhosts2 refused user \"%.100s\" "
+			    "host \"%.100s\" (from packet)", cuser, chost);
+			return 0;
+		}
+		lookup = chost;
+	} else {
+		if (strcasecmp(resolvedname, chost) != 0)
+			logit("userauth_hostbased mismatch: "
+			    "client sends %s, but we resolve %s to %s",
+			    chost, ipaddr, resolvedname);
+		if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) {
+			debug2_f("auth_rhosts2 refused "
+			    "user \"%.100s\" host \"%.100s\" addr \"%.100s\"",
+			    cuser, resolvedname, ipaddr);
+			return 0;
+		}
+		lookup = resolvedname;
+	}
+	debug2_f("access allowed by auth_rhosts2");
+
+	if (sshkey_is_cert(key) &&
+	    sshkey_cert_check_authority_now(key, 1, 0, 0, lookup, &reason)) {
+		error("%s", reason);
+		auth_debug_add("%s", reason);
+		return 0;
+	}
+
+	host_status = check_key_in_hostfiles(pw, key, lookup,
+	    _PATH_SSH_SYSTEM_HOSTFILE,
+	    options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
+
+	/* backward compat if no key has been found. */
+	if (host_status == HOST_NEW) {
+		host_status = check_key_in_hostfiles(pw, key, lookup,
+		    _PATH_SSH_SYSTEM_HOSTFILE2,
+		    options.ignore_user_known_hosts ? NULL :
+		    _PATH_SSH_USER_HOSTFILE2);
+	}
+
+	if (host_status == HOST_OK) {
+		if (sshkey_is_cert(key)) {
+			if ((fp = sshkey_fingerprint(key->cert->signature_key,
+			    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
+				fatal_f("sshkey_fingerprint fail");
+			verbose("Accepted certificate ID \"%s\" signed by "
+			    "%s CA %s from %s@%s", key->cert->key_id,
+			    sshkey_type(key->cert->signature_key), fp,
+			    cuser, lookup);
+		} else {
+			if ((fp = sshkey_fingerprint(key,
+			    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
+				fatal_f("sshkey_fingerprint fail");
+			verbose("Accepted %s public key %s from %s@%s",
+			    sshkey_type(key), fp, cuser, lookup);
+		}
+		free(fp);
+	}
+
+	return (host_status == HOST_OK);
+}
+
+Authmethod method_hostbased = {
+	"hostbased",
+	NULL,
+	userauth_hostbased,
+	&options.hostbased_authentication
+};