From e1d58c44bd911e5ee4dddb6205e16eb9a03cc736 Mon Sep 17 00:00:00 2001

From: Jakub Jelen <jjelen@redhat.com>

Date: Fri, 7 Aug 2015 10:18:54 +0200

Subject: [PATCH] Possibility tu specify more fingerprint algorithms on client

 side for smother transition

---

 clientloop.c  |  8 ++++----

 readconf.c    | 43 +++++++++++++++++++++++++++++--------------

 readconf.h    |  4 +++-

 ssh_config.5  |  4 ++--

 sshconnect.c  | 48 +++++++++++++++++++++++++++---------------------

 sshconnect2.c |  6 +++---

 6 files changed, 68 insertions(+), 45 deletions(-)

diff --git a/clientloop.c b/clientloop.c

index 87ceb3d..4553114 100644

--- a/clientloop.c

+++ b/clientloop.c

@@ -2194,7 +2194,7 @@ update_known_hosts(struct hostkeys_update_ctx *ctx)

 		if (ctx->keys_seen[i] != 2)

 			continue;

 		if ((fp = sshkey_fingerprint(ctx->keys[i],

-		    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)

+		    options.fingerprint_hash[0], SSH_FP_DEFAULT)) == NULL)

 			fatal("%s: sshkey_fingerprint failed", __func__);

 		do_log2(loglevel, "Learned new hostkey: %s %s",

 		    sshkey_type(ctx->keys[i]), fp);

@@ -2202,7 +2202,7 @@ update_known_hosts(struct hostkeys_update_ctx *ctx)

 	}

 	for (i = 0; i < ctx->nold; i++) {

 		if ((fp = sshkey_fingerprint(ctx->old_keys[i],

-		    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)

+		    options.fingerprint_hash[0], SSH_FP_DEFAULT)) == NULL)

 			fatal("%s: sshkey_fingerprint failed", __func__);

 		do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",

 		    sshkey_type(ctx->old_keys[i]), fp);

@@ -2245,7 +2245,7 @@ update_known_hosts(struct hostkeys_update_ctx *ctx)

 	    (r = hostfile_replace_entries(options.user_hostfiles[0],

 	    ctx->host_str, ctx->ip_str, ctx->keys, ctx->nkeys,

 	    options.hash_known_hosts, 0,

-	    options.fingerprint_hash)) != 0)

+	    options.fingerprint_hash[0])) != 0)

 		error("%s: hostfile_replace_entries failed: %s",

 		    __func__, ssh_err(r));

 }

@@ -2358,7 +2358,7 @@ client_input_hostkeys(void)

 			error("%s: parse key: %s", __func__, ssh_err(r));

 			goto out;

 		}

-		fp = sshkey_fingerprint(key, options.fingerprint_hash,

+		fp = sshkey_fingerprint(key, options.fingerprint_hash[0],

 		    SSH_FP_DEFAULT);

 		debug3("%s: received %s key %s", __func__,

 		    sshkey_type(key), fp);

diff --git a/readconf.c b/readconf.c

index 1d03bdf..6af4c62 100644

--- a/readconf.c

+++ b/readconf.c

@@ -1471,16 +1471,18 @@ parse_keytypes:

 		goto parse_string;

 	case oFingerprintHash:

-		intptr = &options->fingerprint_hash;

-		arg = strdelim(&s);

-		if (!arg || *arg == '\0')

-			fatal("%.200s line %d: Missing argument.",

-			    filename, linenum);

-		if ((value = ssh_digest_alg_by_name(arg)) == -1)

-			fatal("%.200s line %d: Invalid hash algorithm \"%s\".",

-			    filename, linenum, arg);

-		if (*activep && *intptr == -1)

-			*intptr = value;

+		if (*activep && options->num_fingerprint_hash == 0)

+			while ((arg = strdelim(&s)) != NULL && *arg != '\0') {

+				value = ssh_digest_alg_by_name(arg);

+				if (value == -1)

+					fatal("%s line %d: unknown fingerprints algorithm specs: %s.",

+						filename, linenum, arg);

+				if (options->num_fingerprint_hash >= SSH_DIGEST_MAX)

+					fatal("%s line %d: too many fingerprints algorithm specs.",

+						filename, linenum);

+				options->fingerprint_hash[

+					options->num_fingerprint_hash++] = value;

+			}

 		break;

 	case oUpdateHostkeys:

@@ -1673,7 +1675,7 @@ initialize_options(Options * options)

 	options->canonicalize_fallback_local = -1;

 	options->canonicalize_hostname = -1;

 	options->revoked_host_keys = NULL;

-	options->fingerprint_hash = -1;

+	options->num_fingerprint_hash = 0;

 	options->update_hostkeys = -1;

 	options->hostbased_key_types = NULL;

 	options->pubkey_key_types = NULL;

@@ -1851,8 +1853,10 @@ fill_default_options(Options * options)

 		options->canonicalize_fallback_local = 1;

 	if (options->canonicalize_hostname == -1)

 		options->canonicalize_hostname = SSH_CANONICALISE_NO;

-	if (options->fingerprint_hash == -1)

-		options->fingerprint_hash = SSH_FP_HASH_DEFAULT;

+	if (options->num_fingerprint_hash == 0) {

+		options->fingerprint_hash[options->num_fingerprint_hash++] = SSH_DIGEST_SHA256;

+		options->fingerprint_hash[options->num_fingerprint_hash++] = SSH_DIGEST_MD5;

+	}

 	if (options->update_hostkeys == -1)

 		options->update_hostkeys = 0;

 	if (kex_assemble_names(KEX_CLIENT_ENCRYPT, &options->ciphers) != 0 ||

@@ -2189,6 +2193,17 @@ dump_cfg_strarray(OpCodes code, u_int count, char **vals)

 }

 static void

+dump_cfg_fmtarray(OpCodes code, u_int count, int *vals)

+{

+	u_int i;

+

+	printf("%s", lookup_opcode_name(code));

+	for (i = 0; i < count; i++)

+		printf(" %s", fmt_intarg(code, vals[i]));

+	printf("\n");

+}

+

+static void

 dump_cfg_strarray_oneline(OpCodes code, u_int count, char **vals)

 {

 	u_int i;

@@ -2259,7 +2274,6 @@ dump_client_config(Options *o, const char *host)

 	dump_cfg_fmtint(oEnableSSHKeysign, o->enable_ssh_keysign);

 	dump_cfg_fmtint(oClearAllForwardings, o->clear_forwardings);

 	dump_cfg_fmtint(oExitOnForwardFailure, o->exit_on_forward_failure);

-	dump_cfg_fmtint(oFingerprintHash, o->fingerprint_hash);

 	dump_cfg_fmtint(oForwardAgent, o->forward_agent);

 	dump_cfg_fmtint(oForwardX11, o->forward_x11);

 	dump_cfg_fmtint(oForwardX11Trusted, o->forward_x11_trusted);

@@ -2328,6 +2342,7 @@ dump_client_config(Options *o, const char *host)

 	dump_cfg_strarray_oneline(oGlobalKnownHostsFile, o->num_system_hostfiles, o->system_hostfiles);

 	dump_cfg_strarray_oneline(oUserKnownHostsFile, o->num_user_hostfiles, o->user_hostfiles);

 	dump_cfg_strarray(oSendEnv, o->num_send_env, o->send_env);

+	dump_cfg_fmtarray(oFingerprintHash, o->num_fingerprint_hash, o->fingerprint_hash);

 	/* Special cases */

diff --git a/readconf.h b/readconf.h

index bb2d552..d817f92 100644

--- a/readconf.h

+++ b/readconf.h

@@ -21,6 +21,7 @@

 #define MAX_SEND_ENV		256

 #define SSH_MAX_HOSTS_FILES	32

 #define MAX_CANON_DOMAINS	32

+#define MAX_SSH_DIGESTS	32

 #define PATH_MAX_SUN		(sizeof((struct sockaddr_un *)0)->sun_path)

 struct allowed_cname {

@@ -146,7 +147,8 @@ typedef struct {

 	char	*revoked_host_keys;

-	int	 fingerprint_hash;

+	int num_fingerprint_hash;

+	int 	fingerprint_hash[MAX_SSH_DIGESTS];

 	int	 update_hostkeys; /* one of SSH_UPDATE_HOSTKEYS_* */

diff --git a/ssh_config.5 b/ssh_config.5

index 5b0975f..e8e6458 100644

--- a/ssh_config.5

+++ b/ssh_config.5

@@ -647,13 +647,13 @@ or

 The default is

 .Dq no .

 .It Cm FingerprintHash

-Specifies the hash algorithm used when displaying key fingerprints.

+Specifies the hash algorithms used when displaying key fingerprints.

 Valid options are:

 .Dq md5

 and

 .Dq sha256 .

 The default is

-.Dq sha256 .

+.Dq "sha256 md5".

 .It Cm ForwardAgent

 Specifies whether the connection to the authentication agent (if any)

 will be forwarded to the remote machine.

diff --git a/sshconnect.c b/sshconnect.c

index f41960c..e12932f 100644

--- a/sshconnect.c

+++ b/sshconnect.c

@@ -920,9 +920,9 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,

 				    "of known hosts.", type, ip);

 		} else if (options.visual_host_key) {

 			fp = sshkey_fingerprint(host_key,

-			    options.fingerprint_hash, SSH_FP_DEFAULT);

+			    options.fingerprint_hash[0], SSH_FP_DEFAULT);

 			ra = sshkey_fingerprint(host_key,

-			    options.fingerprint_hash, SSH_FP_RANDOMART);

+			    options.fingerprint_hash[0], SSH_FP_RANDOMART);

 			if (fp == NULL || ra == NULL)

 				fatal("%s: sshkey_fingerprint fail", __func__);

 			logit("Host key fingerprint is %s\n%s", fp, ra);

@@ -964,12 +964,6 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,

 			else

 				snprintf(msg1, sizeof(msg1), ".");

 			/* The default */

-			fp = sshkey_fingerprint(host_key,

-			    options.fingerprint_hash, SSH_FP_DEFAULT);

-			ra = sshkey_fingerprint(host_key,

-			    options.fingerprint_hash, SSH_FP_RANDOMART);

-			if (fp == NULL || ra == NULL)

-				fatal("%s: sshkey_fingerprint fail", __func__);

 			msg2[0] = '\0';

 			if (options.verify_host_key_dns) {

 				if (matching_host_key_dns)

@@ -983,16 +977,28 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,

 			}

 			snprintf(msg, sizeof(msg),

 			    "The authenticity of host '%.200s (%s)' can't be "

-			    "established%s\n"

-			    "%s key fingerprint is %s.%s%s\n%s"

+			    "established%s\n", host, ip, msg1);

+			for (i = 0; i < options.num_fingerprint_hash; i++) {

+				fp = sshkey_fingerprint(host_key,

+				    options.fingerprint_hash[i], SSH_FP_DEFAULT);

+				ra = sshkey_fingerprint(host_key,

+				    options.fingerprint_hash[i], SSH_FP_RANDOMART);

+				if (fp == NULL || ra == NULL)

+					fatal("%s: sshkey_fingerprint fail", __func__);

+				len = strlen(msg);

+				snprintf(msg+len, sizeof(msg)-len,

+				    "%s key fingerprint is %s.%s%s\n%s",

+				    type, fp,

+				    options.visual_host_key ? "\n" : "",

+				    options.visual_host_key ? ra : "",

+				    msg2);

+				free(ra);

+				free(fp);

+			}

+			len = strlen(msg);

+			snprintf(msg+len, sizeof(msg)-len,

 			    "Are you sure you want to continue connecting "

-			    "(yes/no)? ",

-			    host, ip, msg1, type, fp,

-			    options.visual_host_key ? "\n" : "",

-			    options.visual_host_key ? ra : "",

-			    msg2);

-			free(ra);

-			free(fp);

+			    "(yes/no)? ");

 			if (!confirm(msg))

 				goto fail;

 			hostkey_trusted = 1; /* user explicitly confirmed */

@@ -1241,7 +1247,7 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)

 	struct sshkey *plain = NULL;

 	if ((fp = sshkey_fingerprint(host_key,

-	    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {

+	    options.fingerprint_hash[0], SSH_FP_DEFAULT)) == NULL) {

 		error("%s: fingerprint host key: %s", __func__, ssh_err(r));

 		r = -1;

 		goto out;

@@ -1405,9 +1411,9 @@ show_other_keys(struct hostkeys *hostkeys, Key *key)

 		if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))

 			continue;

 		fp = sshkey_fingerprint(found->key,

-		    options.fingerprint_hash, SSH_FP_DEFAULT);

+		    options.fingerprint_hash[0], SSH_FP_DEFAULT);

 		ra = sshkey_fingerprint(found->key,

-		    options.fingerprint_hash, SSH_FP_RANDOMART);

+		    options.fingerprint_hash[0], SSH_FP_RANDOMART);

 		if (fp == NULL || ra == NULL)

 			fatal("%s: sshkey_fingerprint fail", __func__);

 		logit("WARNING: %s key found for host %s\n"

@@ -1430,7 +1436,7 @@ warn_changed_key(Key *host_key)

 {

 	char *fp;

-	fp = sshkey_fingerprint(host_key, options.fingerprint_hash,

+	fp = sshkey_fingerprint(host_key, options.fingerprint_hash[0],

 	    SSH_FP_DEFAULT);

 	if (fp == NULL)

 		fatal("%s: sshkey_fingerprint fail", __func__);

diff --git a/sshconnect2.c b/sshconnect2.c

index 7751031..82ed92e 100644

--- a/sshconnect2.c

+++ b/sshconnect2.c

@@ -589,7 +589,7 @@ input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)

 		    key->type, pktype);

 		goto done;

 	}

-	if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,

+	if ((fp = sshkey_fingerprint(key, options.fingerprint_hash[0],

 	    SSH_FP_DEFAULT)) == NULL)

 		goto done;

 	debug2("input_userauth_pk_ok: fp %s", fp);

@@ -1009,7 +1009,7 @@ sign_and_send_pubkey(Authctxt *authctxt, Identity *id)

 	int matched, ret = -1, have_sig = 1;

 	char *fp;

-	if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,

+	if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash[0],

 	    SSH_FP_DEFAULT)) == NULL)

 		return 0;

 	debug3("%s: %s %s", __func__, key_type(id->key), fp);

@@ -1635,7 +1635,7 @@ userauth_hostbased(Authctxt *authctxt)

 		goto out;

 	}

-	if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,

+	if ((fp = sshkey_fingerprint(private, options.fingerprint_hash[0],

 	    SSH_FP_DEFAULT)) == NULL) {

 		error("%s: sshkey_fingerprint failed", __func__);

 		goto out;

diff --git a/ssh-keysign.c b/ssh-keysign.c

index 1dca3e2..23bff7d 100644

--- a/ssh-keysign.c

+++ b/ssh-keysign.c

@@ -275,7 +275,7 @@ main(int argc, char **argv)

 		}

 	}

 	if (!found) {

-		if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,

+		if ((fp = sshkey_fingerprint(key, options.fingerprint_hash[0],

 		    SSH_FP_DEFAULT)) == NULL)

 			fatal("%s: sshkey_fingerprint failed", __progname);

 		fatal("no matching hostkey found for key %s %s",

-- 

2.1.0

diff --git a/sshconnect.c b/sshconnect.c

index de7ace6..f16e606 100644

--- a/sshconnect.c

+++ b/sshconnect.c

@@ -1262,7 +1262,7 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)

 	if (sshkey_is_cert(host_key)) {

 		if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,

-		    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {

+		    options.fingerprint_hash[0], SSH_FP_DEFAULT)) == NULL) {

 			error("%s: fingerprint CA key: %s",

 			    __func__, ssh_err(r));

 			r = -1;