Attachment 2303 Details for Bug 1974 – Incomplete patch for sshd to use ssh-agent for hostkeys

[patch] Incomplete patch for sshd to use ssh-agent for hostkeys

sshd-agent.patch (text/plain), 10.74 KB, created by Zev Weiss on 2013-06-26 13:10:31 AEST

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Creator: Zev Weiss

Created: 2013-06-26 13:10:31 AEST

Size: 10.74 KB

patch

obsolete

>commit 7a199748b4d66d980ec6ec6c3c4213313a587a0a
>Author: Zev Weiss <zev@bewilderbeest.net>
>Date:   2013-06-24 01:04:09 -0700
>
>    Privsep-friendly agent-based encrypted hostkey support.
>    
>    Only the privsep monitor talks to the agent.
>
>diff --git a/auth.h b/auth.h
>index a406e13..d91f845 100644
>--- a/auth.h
>+++ b/auth.h
>@@ -197,6 +197,7 @@ check_key_in_hostfiles(struct passwd *, Key *, const char *,
> 
> /* hostkey handling */
> Key	*get_hostkey_by_index(int);
>+Key	*get_hostkey_public_by_index(int);
> Key	*get_hostkey_public_by_type(int);
> Key	*get_hostkey_private_by_type(int);
> int	 get_hostkey_index(Key *);
>diff --git a/kex.h b/kex.h
>index 680264a..b77a2c2 100644
>--- a/kex.h
>+++ b/kex.h
>@@ -139,6 +139,7 @@ struct Kex {
> 	Key	*(*load_host_public_key)(int);
> 	Key	*(*load_host_private_key)(int);
> 	int	(*host_key_index)(Key *);
>+	void    (*sign)(Key *, Key *, u_char **, u_int *, u_char *, u_int);
> 	void	(*kex[KEX_MAX])(Kex *);
> };
> 
>diff --git a/kexdhs.c b/kexdhs.c
>index 1512863..f6d43f2 100644
>--- a/kexdhs.c
>+++ b/kexdhs.c
>@@ -80,9 +80,6 @@ kexdh_server(Kex *kex)
> 	if (server_host_public == NULL)
> 		fatal("Unsupported hostkey type %d", kex->hostkey_type);
> 	server_host_private = kex->load_host_private_key(kex->hostkey_type);
>-	if (server_host_private == NULL)
>-		fatal("Missing private key for hostkey type %d",
>-		    kex->hostkey_type);
> 
> 	/* key, cert */
> 	if ((dh_client_pub = BN_new()) == NULL)
>@@ -144,9 +141,8 @@ kexdh_server(Kex *kex)
> 	}
> 
> 	/* sign H */
>-	if (PRIVSEP(key_sign(server_host_private, &signature, &slen, hash,
>-	    hashlen)) < 0)
>-		fatal("kexdh_server: key_sign failed");
>+	kex->sign(server_host_private, server_host_public, &signature, &slen,
>+	    hash, hashlen);
> 
> 	/* destroy_sensitive_data(); */
> 
>diff --git a/kexecdhs.c b/kexecdhs.c
>index c42dcf4..eec5fb6 100644
>--- a/kexecdhs.c
>+++ b/kexecdhs.c
>@@ -78,9 +78,6 @@ kexecdh_server(Kex *kex)
> 	if (server_host_public == NULL)
> 		fatal("Unsupported hostkey type %d", kex->hostkey_type);
> 	server_host_private = kex->load_host_private_key(kex->hostkey_type);
>-	if (server_host_private == NULL)
>-		fatal("Missing private key for hostkey type %d",
>-		    kex->hostkey_type);
> 
> 	debug("expecting SSH2_MSG_KEX_ECDH_INIT");
> 	packet_read_expect(SSH2_MSG_KEX_ECDH_INIT);
>@@ -139,9 +136,8 @@ kexecdh_server(Kex *kex)
> 	}
> 
> 	/* sign H */
>-	if (PRIVSEP(key_sign(server_host_private, &signature, &slen,
>-	    hash, hashlen)) < 0)
>-		fatal("kexdh_server: key_sign failed");
>+	kex->sign(server_host_private, server_host_public, &signature, &slen,
>+	    hash, hashlen);
> 
> 	/* destroy_sensitive_data(); */
> 
>diff --git a/kexgexs.c b/kexgexs.c
>index a543dda..3ef7710 100644
>--- a/kexgexs.c
>+++ b/kexgexs.c
>@@ -68,10 +68,6 @@ kexgex_server(Kex *kex)
> 	if (server_host_public == NULL)
> 		fatal("Unsupported hostkey type %d", kex->hostkey_type);
> 	server_host_private = kex->load_host_private_key(kex->hostkey_type);
>-	if (server_host_private == NULL)
>-		fatal("Missing private key for hostkey type %d",
>-		    kex->hostkey_type);
>-
> 
> 	type = packet_read();
> 	switch (type) {
>@@ -187,9 +183,8 @@ kexgex_server(Kex *kex)
> 	}
> 
> 	/* sign H */
>-	if (PRIVSEP(key_sign(server_host_private, &signature, &slen, hash,
>-	    hashlen)) < 0)
>-		fatal("kexgex_server: key_sign failed");
>+	kex->sign(server_host_private, server_host_public, &signature, &slen,
>+	    hash, hashlen);
> 
> 	/* destroy_sensitive_data(); */
> 
>diff --git a/monitor.c b/monitor.c
>index 7286126..8f289b5 100644
>--- a/monitor.c
>+++ b/monitor.c
>@@ -97,6 +97,7 @@
> #include "ssh2.h"
> #include "jpake.h"
> #include "roaming.h"
>+#include "authfd.h"
> 
> #ifdef GSSAPI
> static Gssctxt *gsscontext = NULL;
>@@ -686,6 +687,8 @@ mm_answer_moduli(int sock, Buffer *m)
> 	return (0);
> }
> 
>+extern AuthenticationConnection *auth_conn;
>+
> int
> mm_answer_sign(int sock, Buffer *m)
> {
>@@ -714,10 +717,16 @@ mm_answer_sign(int sock, Buffer *m)
> 		memcpy(session_id2, p, session_id2_len);
> 	}
> 
>-	if ((key = get_hostkey_by_index(keyid)) == NULL)
>+	if ((key = get_hostkey_by_index(keyid)) != NULL) {
>+		if (key_sign(key, &signature, &siglen, p, datlen) < 0)
>+			fatal("%s: key_sign failed", __func__);
>+	} else if ((key = get_hostkey_public_by_index(keyid)) != NULL &&
>+	    auth_conn != NULL) {
>+		if (ssh_agent_sign(auth_conn, key, &signature, &siglen, p,
>+		    datlen) < 0)
>+			fatal("%s: ssh_agent_sign failed", __func__);
>+	} else
> 		fatal("%s: no hostkey from index %d", __func__, keyid);
>-	if (key_sign(key, &signature, &siglen, p, datlen) < 0)
>-		fatal("%s: key_sign failed", __func__);
> 
> 	debug3("%s: signature %p(%u)", __func__, signature, siglen);
> 
>diff --git a/sshd.c b/sshd.c
>index 1306a62..a4a788b 100644
>--- a/sshd.c
>+++ b/sshd.c
>@@ -106,6 +106,7 @@
> #include "canohost.h"
> #include "hostfile.h"
> #include "auth.h"
>+#include "authfd.h"
> #include "misc.h"
> #include "msg.h"
> #include "dispatch.h"
>@@ -194,6 +195,9 @@ char *server_version_string = NULL;
> /* for rekeying XXX fixme */
> Kex *xxx_kex;
> 
>+/* Daemon's agent connection */
>+AuthenticationConnection *auth_conn = NULL;
>+
> /*
>  * Any really sensitive data in the application is contained in this
>  * structure. The idea is that this structure could be locked into memory so
>@@ -206,6 +210,7 @@ struct {
> 	Key	*server_key;		/* ephemeral server key */
> 	Key	*ssh1_host_key;		/* ssh1 host key */
> 	Key	**host_keys;		/* all private host keys */
>+	Key	**host_pubkeys;		/* all public host keys */
> 	Key	**host_certificates;	/* all public host certificates */
> 	int	have_ssh1_key;
> 	int	have_ssh2_key;
>@@ -652,11 +657,18 @@ privsep_preauth(Authctxt *authctxt)
> 	} else if (pid != 0) {
> 		debug2("Network child is on pid %ld", (long)pid);
> 
>+		auth_conn = ssh_get_authentication_connection();
>+
> 		pmonitor->m_pid = pid;
> 		if (box != NULL)
> 			ssh_sandbox_parent_preauth(box, pid);
> 		monitor_child_preauth(authctxt, pmonitor);
> 
>+		if (auth_conn) {
>+			ssh_close_authentication_connection(auth_conn);
>+			auth_conn = NULL;
>+		}
>+
> 		/* Sync memory */
> 		monitor_sync(pmonitor);
> 
>@@ -704,10 +716,11 @@ privsep_postauth(Authctxt *authctxt)
> 	u_int32_t rnd[256];
> 
> #ifdef DISABLE_FD_PASSING
>-	if (1) {
>+	if (1)
> #else
>-	if (authctxt->pw->pw_uid == 0 || options.use_login) {
>+	if (authctxt->pw->pw_uid == 0 || options.use_login)
> #endif
>+	{
> 		/* File descriptor passing is broken or root login */
> 		use_privsep = 0;
> 		goto skip;
>@@ -767,6 +780,8 @@ list_hostkey_types(void)
> 	for (i = 0; i < options.num_host_key_files; i++) {
> 		key = sensitive_data.host_keys[i];
> 		if (key == NULL)
>+			key = sensitive_data.host_pubkeys[i];
>+		if (key == NULL)
> 			continue;
> 		switch (key->type) {
> 		case KEY_RSA:
>@@ -819,6 +834,8 @@ get_hostkey_by_type(int type, int need_private)
> 			break;
> 		default:
> 			key = sensitive_data.host_keys[i];
>+			if (key == NULL && !need_private)
>+				key = sensitive_data.host_pubkeys[i];
> 			break;
> 		}
> 		if (key != NULL && key->type == type)
>@@ -848,6 +865,14 @@ get_hostkey_by_index(int ind)
> 	return (sensitive_data.host_keys[ind]);
> }
> 
>+Key *
>+get_hostkey_public_by_index(int ind)
>+{
>+	if (ind < 0 || ind >= options.num_host_key_files)
>+		return (NULL);
>+	return (sensitive_data.host_pubkeys[ind]);
>+}
>+
> int
> get_hostkey_index(Key *key)
> {
>@@ -860,6 +885,8 @@ get_hostkey_index(Key *key)
> 		} else {
> 			if (key == sensitive_data.host_keys[i])
> 				return (i);
>+			if (key == sensitive_data.host_pubkeys[i])
>+				return (i);
> 		}
> 	}
> 	return (-1);
>@@ -1344,6 +1371,9 @@ main(int ac, char **av)
> 	u_int64_t ibytes, obytes;
> 	mode_t new_umask;
> 	Key *key;
>+	Key *pubkey;
>+	char *pubkey_comment;
>+	int have_agent, keytype;
> 	Authctxt *authctxt;
> 	struct connection_info *connection_info = get_connection_info(0, 0);
> 
>@@ -1623,22 +1653,40 @@ main(int ac, char **av)
> 	}
> 	endpwent();
> 
>-	/* load private host keys */
>+	/* load host keys */
> 	sensitive_data.host_keys = xcalloc(options.num_host_key_files,
> 	    sizeof(Key *));
>-	for (i = 0; i < options.num_host_key_files; i++)
>+	sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
>+	    sizeof(Key *));
>+	for (i = 0; i < options.num_host_key_files; i++) {
> 		sensitive_data.host_keys[i] = NULL;
>+		sensitive_data.host_pubkeys[i] = NULL;
>+	}
>+
>+	have_agent = ssh_agent_present();
> 
> 	for (i = 0; i < options.num_host_key_files; i++) {
> 		key = key_load_private(options.host_key_files[i], "", NULL);
>+		pubkey = key_load_public(options.host_key_files[i],
>+		    &pubkey_comment);
> 		sensitive_data.host_keys[i] = key;
>-		if (key == NULL) {
>+		sensitive_data.host_pubkeys[i] = pubkey;
>+
>+		if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 &&
>+		    have_agent) {
>+			debug("will rely on agent for hostkey %s",
>+			    options.host_key_files[i]);
>+			keytype = pubkey->type;
>+		} else if (key == NULL) {
> 			error("Could not load host key: %s",
> 			    options.host_key_files[i]);
> 			sensitive_data.host_keys[i] = NULL;
>+			sensitive_data.host_pubkeys[i] = NULL;
> 			continue;
>-		}
>-		switch (key->type) {
>+		} else
>+			keytype = key->type;
>+
>+		switch (keytype) {
> 		case KEY_RSA1:
> 			sensitive_data.ssh1_host_key = key;
> 			sensitive_data.have_ssh1_key = 1;
>@@ -1649,8 +1697,8 @@ main(int ac, char **av)
> 			sensitive_data.have_ssh2_key = 1;
> 			break;
> 		}
>-		debug("private host key: #%d type %d %s", i, key->type,
>-		    key_type(key));
>+		debug("private host key: #%d type %d %s", i, keytype,
>+		    key_type(key ? key : pubkey));
> 	}
> 	if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
> 		logit("Disabling protocol version 1. Could not load host key");
>@@ -2020,15 +2068,21 @@ main(int ac, char **av)
> 	buffer_init(&loginmsg);
> 	auth_debug_reset();
> 
>-	if (use_privsep)
>+	if (use_privsep) {
> 		if (privsep_preauth(authctxt) == 1)
> 			goto authenticated;
>+	} else if (compat20)
>+		auth_conn = ssh_get_authentication_connection();
> 
> 	/* perform the key exchange */
> 	/* authenticate user and start session */
> 	if (compat20) {
> 		do_ssh2_kex();
> 		do_authentication2(authctxt);
>+		if (!use_privsep && auth_conn) {
>+			ssh_close_authentication_connection(auth_conn);
>+			auth_conn = NULL;
>+		}
> 	} else {
> 		do_ssh1_kex();
> 		do_authentication(authctxt);
>@@ -2336,6 +2390,23 @@ do_ssh1_kex(void)
> 	packet_write_wait();
> }
> 
>+static void
>+kex_server_sign(Key *privkey, Key *pubkey, u_char **signature, u_int *slen,
>+    u_char *data, u_int dlen)
>+{
>+	if (privkey) {
>+		if (PRIVSEP(key_sign(privkey, signature, slen, data, dlen) < 0))
>+			fatal("%s: key_sign failed", __func__);
>+	} else if (use_privsep) {
>+		if (mm_key_sign(pubkey, signature, slen, data, dlen) < 0)
>+			fatal("%s: pubkey_sign failed", __func__);
>+	} else {
>+		if (ssh_agent_sign(auth_conn, pubkey, signature, slen, data,
>+		    dlen))
>+			fatal("%s: ssh_agent_sign failed", __func__);
>+	}
>+}
>+
> /*
>  * SSH2 key exchange: diffie-hellman-group1-sha1
>  */
>@@ -2386,6 +2457,7 @@ do_ssh2_kex(void)
> 	kex->load_host_public_key=&get_hostkey_public_by_type;
> 	kex->load_host_private_key=&get_hostkey_private_by_type;
> 	kex->host_key_index=&get_hostkey_index;
>+	kex->sign = kex_server_sign;
> 
> 	xxx_kex = kex;
>

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Attachments on bug 1974: 2125 | 2303 | 2306 | 2307 | 2308 | 2309