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

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

1 files changed, 340 insertions, 0 deletions

diff --git a/dns.c b/dns.c
new file mode 100644
index 0000000..f2310be
--- /dev/null
+++ b/dns.c
@@ -0,0 +1,340 @@
+/* $OpenBSD: dns.c,v 1.42 2022/02/01 23:32:51 djm Exp $ */
+
+/*
+ * Copyright (c) 2003 Wesley Griffin. All rights reserved.
+ * Copyright (c) 2003 Jakob Schlyter. 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 <sys/socket.h>
+
+#include <netdb.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include "xmalloc.h"
+#include "sshkey.h"
+#include "ssherr.h"
+#include "dns.h"
+#include "log.h"
+#include "digest.h"
+
+static const char * const errset_text[] = {
+	"success",		/* 0 ERRSET_SUCCESS */
+	"out of memory",	/* 1 ERRSET_NOMEMORY */
+	"general failure",	/* 2 ERRSET_FAIL */
+	"invalid parameter",	/* 3 ERRSET_INVAL */
+	"name does not exist",	/* 4 ERRSET_NONAME */
+	"data does not exist",	/* 5 ERRSET_NODATA */
+};
+
+static const char *
+dns_result_totext(unsigned int res)
+{
+	switch (res) {
+	case ERRSET_SUCCESS:
+		return errset_text[ERRSET_SUCCESS];
+	case ERRSET_NOMEMORY:
+		return errset_text[ERRSET_NOMEMORY];
+	case ERRSET_FAIL:
+		return errset_text[ERRSET_FAIL];
+	case ERRSET_INVAL:
+		return errset_text[ERRSET_INVAL];
+	case ERRSET_NONAME:
+		return errset_text[ERRSET_NONAME];
+	case ERRSET_NODATA:
+		return errset_text[ERRSET_NODATA];
+	default:
+		return "unknown error";
+	}
+}
+
+/*
+ * Read SSHFP parameters from key buffer.
+ * Caller must free digest which is allocated by sshkey_fingerprint_raw().
+ */
+static int
+dns_read_key(u_int8_t *algorithm, u_int8_t *digest_type,
+    u_char **digest, size_t *digest_len, struct sshkey *key)
+{
+	int r, success = 0;
+	int fp_alg = -1;
+
+	switch (key->type) {
+	case KEY_RSA:
+		*algorithm = SSHFP_KEY_RSA;
+		break;
+	case KEY_DSA:
+		*algorithm = SSHFP_KEY_DSA;
+		break;
+	case KEY_ECDSA:
+		*algorithm = SSHFP_KEY_ECDSA;
+		break;
+	case KEY_ED25519:
+		*algorithm = SSHFP_KEY_ED25519;
+		break;
+	case KEY_XMSS:
+		*algorithm = SSHFP_KEY_XMSS;
+		break;
+	default:
+		*algorithm = SSHFP_KEY_RESERVED; /* 0 */
+	}
+
+	switch (*digest_type) {
+	case SSHFP_HASH_SHA1:
+		fp_alg = SSH_DIGEST_SHA1;
+		break;
+	case SSHFP_HASH_SHA256:
+		fp_alg = SSH_DIGEST_SHA256;
+		break;
+	default:
+		*digest_type = SSHFP_HASH_RESERVED; /* 0 */
+	}
+
+	if (*algorithm && *digest_type) {
+		if ((r = sshkey_fingerprint_raw(key, fp_alg, digest,
+		    digest_len)) != 0)
+			fatal_fr(r, "sshkey_fingerprint_raw");
+		success = 1;
+	} else {
+		*digest = NULL;
+		*digest_len = 0;
+	}
+
+	return success;
+}
+
+/*
+ * Read SSHFP parameters from rdata buffer.
+ */
+static int
+dns_read_rdata(u_int8_t *algorithm, u_int8_t *digest_type,
+    u_char **digest, size_t *digest_len, u_char *rdata, int rdata_len)
+{
+	int success = 0;
+
+	*algorithm = SSHFP_KEY_RESERVED;
+	*digest_type = SSHFP_HASH_RESERVED;
+
+	if (rdata_len >= 2) {
+		*algorithm = rdata[0];
+		*digest_type = rdata[1];
+		*digest_len = rdata_len - 2;
+
+		if (*digest_len > 0) {
+			*digest = xmalloc(*digest_len);
+			memcpy(*digest, rdata + 2, *digest_len);
+		} else {
+			*digest = (u_char *)xstrdup("");
+		}
+
+		success = 1;
+	}
+
+	return success;
+}
+
+/*
+ * Check if hostname is numerical.
+ * Returns -1 if hostname is numeric, 0 otherwise
+ */
+static int
+is_numeric_hostname(const char *hostname)
+{
+	struct addrinfo hints, *ai;
+
+	/*
+	 * We shouldn't ever get a null host but if we do then log an error
+	 * and return -1 which stops DNS key fingerprint processing.
+	 */
+	if (hostname == NULL) {
+		error("is_numeric_hostname called with NULL hostname");
+		return -1;
+	}
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_socktype = SOCK_DGRAM;
+	hints.ai_flags = AI_NUMERICHOST;
+
+	if (getaddrinfo(hostname, NULL, &hints, &ai) == 0) {
+		freeaddrinfo(ai);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Verify the given hostname, address and host key using DNS.
+ * Returns 0 if lookup succeeds, -1 otherwise
+ */
+int
+verify_host_key_dns(const char *hostname, struct sockaddr *address,
+    struct sshkey *hostkey, int *flags)
+{
+	u_int counter;
+	int result;
+	struct rrsetinfo *fingerprints = NULL;
+
+	u_int8_t hostkey_algorithm;
+	u_char *hostkey_digest;
+	size_t hostkey_digest_len;
+
+	u_int8_t dnskey_algorithm;
+	u_int8_t dnskey_digest_type;
+	u_char *dnskey_digest;
+	size_t dnskey_digest_len;
+
+	*flags = 0;
+
+	debug3("verify_host_key_dns");
+	if (hostkey == NULL)
+		fatal("No key to look up!");
+
+	if (is_numeric_hostname(hostname)) {
+		debug("skipped DNS lookup for numerical hostname");
+		return -1;
+	}
+
+	result = getrrsetbyname(hostname, DNS_RDATACLASS_IN,
+	    DNS_RDATATYPE_SSHFP, 0, &fingerprints);
+	if (result) {
+		verbose("DNS lookup error: %s", dns_result_totext(result));
+		return -1;
+	}
+
+	if (fingerprints->rri_flags & RRSET_VALIDATED) {
+		*flags |= DNS_VERIFY_SECURE;
+		debug("found %d secure fingerprints in DNS",
+		    fingerprints->rri_nrdatas);
+	} else {
+		debug("found %d insecure fingerprints in DNS",
+		    fingerprints->rri_nrdatas);
+	}
+
+	if (fingerprints->rri_nrdatas)
+		*flags |= DNS_VERIFY_FOUND;
+
+	for (counter = 0; counter < fingerprints->rri_nrdatas; counter++) {
+		/*
+		 * Extract the key from the answer. Ignore any badly
+		 * formatted fingerprints.
+		 */
+		if (!dns_read_rdata(&dnskey_algorithm, &dnskey_digest_type,
+		    &dnskey_digest, &dnskey_digest_len,
+		    fingerprints->rri_rdatas[counter].rdi_data,
+		    fingerprints->rri_rdatas[counter].rdi_length)) {
+			verbose("Error parsing fingerprint from DNS.");
+			continue;
+		}
+		debug3_f("checking SSHFP type %d fptype %d", dnskey_algorithm,
+		    dnskey_digest_type);
+
+		/* Calculate host key fingerprint. */
+		if (!dns_read_key(&hostkey_algorithm, &dnskey_digest_type,
+		    &hostkey_digest, &hostkey_digest_len, hostkey)) {
+			error("Error calculating key fingerprint.");
+			freerrset(fingerprints);
+			return -1;
+		}
+
+		/* Check if the current key is the same as the given key */
+		if (hostkey_algorithm == dnskey_algorithm &&
+		    hostkey_digest_len == dnskey_digest_len) {
+			if (timingsafe_bcmp(hostkey_digest, dnskey_digest,
+			    hostkey_digest_len) == 0) {
+				debug_f("matched SSHFP type %d fptype %d",
+				    dnskey_algorithm, dnskey_digest_type);
+				*flags |= DNS_VERIFY_MATCH;
+			} else {
+				debug_f("failed SSHFP type %d fptype %d",
+				    dnskey_algorithm, dnskey_digest_type);
+				*flags |= DNS_VERIFY_FAILED;
+			}
+		}
+		free(dnskey_digest);
+		free(hostkey_digest); /* from sshkey_fingerprint_raw() */
+	}
+
+	freerrset(fingerprints);
+
+	/* If any fingerprint failed to validate, return failure. */
+	if (*flags & DNS_VERIFY_FAILED)
+		*flags &= ~DNS_VERIFY_MATCH;
+
+	if (*flags & DNS_VERIFY_FOUND)
+		if (*flags & DNS_VERIFY_MATCH)
+			debug("matching host key fingerprint found in DNS");
+		else
+			debug("mismatching host key fingerprint found in DNS");
+	else
+		debug("no host key fingerprint found in DNS");
+
+	return 0;
+}
+
+/*
+ * Export the fingerprint of a key as a DNS resource record
+ */
+int
+export_dns_rr(const char *hostname, struct sshkey *key, FILE *f, int generic)
+{
+	u_int8_t rdata_pubkey_algorithm = 0;
+	u_int8_t rdata_digest_type = SSHFP_HASH_RESERVED;
+	u_int8_t dtype;
+	u_char *rdata_digest;
+	size_t i, rdata_digest_len;
+	int success = 0;
+
+	for (dtype = SSHFP_HASH_SHA1; dtype < SSHFP_HASH_MAX; dtype++) {
+		rdata_digest_type = dtype;
+		if (dns_read_key(&rdata_pubkey_algorithm, &rdata_digest_type,
+		    &rdata_digest, &rdata_digest_len, key)) {
+			if (generic) {
+				fprintf(f, "%s IN TYPE%d \\# %zu %02x %02x ",
+				    hostname, DNS_RDATATYPE_SSHFP,
+				    2 + rdata_digest_len,
+				    rdata_pubkey_algorithm, rdata_digest_type);
+			} else {
+				fprintf(f, "%s IN SSHFP %d %d ", hostname,
+				    rdata_pubkey_algorithm, rdata_digest_type);
+			}
+			for (i = 0; i < rdata_digest_len; i++)
+				fprintf(f, "%02x", rdata_digest[i]);
+			fprintf(f, "\n");
+			free(rdata_digest); /* from sshkey_fingerprint_raw() */
+			success = 1;
+		}
+	}
+
+	/* No SSHFP record was generated at all */
+	if (success == 0) {
+		error_f("unsupported algorithm and/or digest_type");
+	}
+
+	return success;
+}