Adding upstream version 1:9.6p1.upstream/1%9.6p1

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

1 files changed, 778 insertions, 0 deletions

diff --git a/authfd.c b/authfd.c
new file mode 100644
index 0000000..e04ad0c
--- /dev/null
+++ b/authfd.c
@@ -0,0 +1,778 @@
+/* $OpenBSD: authfd.c,v 1.134 2023/12/18 14:46:56 djm Exp $ */
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * Functions for connecting the local authentication agent.
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose.  Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ *
+ * SSH2 implementation,
+ * 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 <sys/un.h>
+#include <sys/socket.h>
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <string.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "xmalloc.h"
+#include "ssh.h"
+#include "sshbuf.h"
+#include "sshkey.h"
+#include "authfd.h"
+#include "cipher.h"
+#include "log.h"
+#include "atomicio.h"
+#include "misc.h"
+#include "ssherr.h"
+
+#define MAX_AGENT_IDENTITIES	2048		/* Max keys in agent reply */
+#define MAX_AGENT_REPLY_LEN	(256 * 1024)	/* Max bytes in agent reply */
+
+/* macro to check for "agent failure" message */
+#define agent_failed(x) \
+    ((x == SSH_AGENT_FAILURE) || \
+    (x == SSH_COM_AGENT2_FAILURE) || \
+    (x == SSH2_AGENT_FAILURE))
+
+/* Convert success/failure response from agent to a err.h status */
+static int
+decode_reply(u_char type)
+{
+	if (agent_failed(type))
+		return SSH_ERR_AGENT_FAILURE;
+	else if (type == SSH_AGENT_SUCCESS)
+		return 0;
+	else
+		return SSH_ERR_INVALID_FORMAT;
+}
+
+/*
+ * Opens an authentication socket at the provided path and stores the file
+ * descriptor in fdp. Returns 0 on success and an error on failure.
+ */
+int
+ssh_get_authentication_socket_path(const char *authsocket, int *fdp)
+{
+	int sock, oerrno;
+	struct sockaddr_un sunaddr;
+
+	debug3_f("path '%s'", authsocket);
+	memset(&sunaddr, 0, sizeof(sunaddr));
+	sunaddr.sun_family = AF_UNIX;
+	strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
+
+	if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) == -1)
+		return SSH_ERR_SYSTEM_ERROR;
+
+	/* close on exec */
+	if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1 ||
+	    connect(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) == -1) {
+		oerrno = errno;
+		close(sock);
+		errno = oerrno;
+		return SSH_ERR_SYSTEM_ERROR;
+	}
+	if (fdp != NULL)
+		*fdp = sock;
+	else
+		close(sock);
+	return 0;
+}
+
+/*
+ * Opens the default authentication socket and stores the file descriptor in
+ * fdp. Returns 0 on success and an error on failure.
+ */
+int
+ssh_get_authentication_socket(int *fdp)
+{
+	const char *authsocket;
+
+	if (fdp != NULL)
+		*fdp = -1;
+
+	authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
+	if (authsocket == NULL || *authsocket == '\0')
+		return SSH_ERR_AGENT_NOT_PRESENT;
+
+	return ssh_get_authentication_socket_path(authsocket, fdp);
+}
+
+/* Communicate with agent: send request and read reply */
+static int
+ssh_request_reply(int sock, struct sshbuf *request, struct sshbuf *reply)
+{
+	int r;
+	size_t l, len;
+	char buf[1024];
+
+	/* Get the length of the message, and format it in the buffer. */
+	len = sshbuf_len(request);
+	POKE_U32(buf, len);
+
+	/* Send the length and then the packet to the agent. */
+	if (atomicio(vwrite, sock, buf, 4) != 4 ||
+	    atomicio(vwrite, sock, sshbuf_mutable_ptr(request),
+	    sshbuf_len(request)) != sshbuf_len(request))
+		return SSH_ERR_AGENT_COMMUNICATION;
+	/*
+	 * Wait for response from the agent.  First read the length of the
+	 * response packet.
+	 */
+	if (atomicio(read, sock, buf, 4) != 4)
+	    return SSH_ERR_AGENT_COMMUNICATION;
+
+	/* Extract the length, and check it for sanity. */
+	len = PEEK_U32(buf);
+	if (len > MAX_AGENT_REPLY_LEN)
+		return SSH_ERR_INVALID_FORMAT;
+
+	/* Read the rest of the response in to the buffer. */
+	sshbuf_reset(reply);
+	while (len > 0) {
+		l = len;
+		if (l > sizeof(buf))
+			l = sizeof(buf);
+		if (atomicio(read, sock, buf, l) != l)
+			return SSH_ERR_AGENT_COMMUNICATION;
+		if ((r = sshbuf_put(reply, buf, l)) != 0)
+			return r;
+		len -= l;
+	}
+	return 0;
+}
+
+/* Communicate with agent: sent request, read and decode status reply */
+static int
+ssh_request_reply_decode(int sock, struct sshbuf *request)
+{
+	struct sshbuf *reply;
+	int r;
+	u_char type;
+
+	if ((reply = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((r = ssh_request_reply(sock, request, reply)) != 0 ||
+	    (r = sshbuf_get_u8(reply, &type)) != 0 ||
+	    (r = decode_reply(type)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	sshbuf_free(reply);
+	return r;
+}
+
+/*
+ * Closes the agent socket if it should be closed (depends on how it was
+ * obtained).  The argument must have been returned by
+ * ssh_get_authentication_socket().
+ */
+void
+ssh_close_authentication_socket(int sock)
+{
+	if (getenv(SSH_AUTHSOCKET_ENV_NAME))
+		close(sock);
+}
+
+/* Lock/unlock agent */
+int
+ssh_lock_agent(int sock, int lock, const char *password)
+{
+	int r;
+	u_char type = lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK;
+	struct sshbuf *msg;
+
+	if ((msg = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((r = sshbuf_put_u8(msg, type)) != 0 ||
+	    (r = sshbuf_put_cstring(msg, password)) != 0 ||
+	    (r = ssh_request_reply_decode(sock, msg)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	sshbuf_free(msg);
+	return r;
+}
+
+
+static int
+deserialise_identity2(struct sshbuf *ids, struct sshkey **keyp, char **commentp)
+{
+	int r;
+	char *comment = NULL;
+	const u_char *blob;
+	size_t blen;
+
+	if ((r = sshbuf_get_string_direct(ids, &blob, &blen)) != 0 ||
+	    (r = sshbuf_get_cstring(ids, &comment, NULL)) != 0)
+		goto out;
+	if ((r = sshkey_from_blob(blob, blen, keyp)) != 0)
+		goto out;
+	if (commentp != NULL) {
+		*commentp = comment;
+		comment = NULL;
+	}
+	r = 0;
+ out:
+	free(comment);
+	return r;
+}
+
+/*
+ * Fetch list of identities held by the agent.
+ */
+int
+ssh_fetch_identitylist(int sock, struct ssh_identitylist **idlp)
+{
+	u_char type;
+	u_int32_t num, i;
+	struct sshbuf *msg;
+	struct ssh_identitylist *idl = NULL;
+	int r;
+
+	/*
+	 * Send a message to the agent requesting for a list of the
+	 * identities it can represent.
+	 */
+	if ((msg = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_REQUEST_IDENTITIES)) != 0)
+		goto out;
+
+	if ((r = ssh_request_reply(sock, msg, msg)) != 0)
+		goto out;
+
+	/* Get message type, and verify that we got a proper answer. */
+	if ((r = sshbuf_get_u8(msg, &type)) != 0)
+		goto out;
+	if (agent_failed(type)) {
+		r = SSH_ERR_AGENT_FAILURE;
+		goto out;
+	} else if (type != SSH2_AGENT_IDENTITIES_ANSWER) {
+		r = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+
+	/* Get the number of entries in the response and check it for sanity. */
+	if ((r = sshbuf_get_u32(msg, &num)) != 0)
+		goto out;
+	if (num > MAX_AGENT_IDENTITIES) {
+		r = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+	if (num == 0) {
+		r = SSH_ERR_AGENT_NO_IDENTITIES;
+		goto out;
+	}
+
+	/* Deserialise the response into a list of keys/comments */
+	if ((idl = calloc(1, sizeof(*idl))) == NULL ||
+	    (idl->keys = calloc(num, sizeof(*idl->keys))) == NULL ||
+	    (idl->comments = calloc(num, sizeof(*idl->comments))) == NULL) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	for (i = 0; i < num;) {
+		if ((r = deserialise_identity2(msg, &(idl->keys[i]),
+		    &(idl->comments[i]))) != 0) {
+			if (r == SSH_ERR_KEY_TYPE_UNKNOWN) {
+				/* Gracefully skip unknown key types */
+				num--;
+				continue;
+			} else
+				goto out;
+		}
+		i++;
+	}
+	idl->nkeys = num;
+	*idlp = idl;
+	idl = NULL;
+	r = 0;
+ out:
+	sshbuf_free(msg);
+	if (idl != NULL)
+		ssh_free_identitylist(idl);
+	return r;
+}
+
+void
+ssh_free_identitylist(struct ssh_identitylist *idl)
+{
+	size_t i;
+
+	if (idl == NULL)
+		return;
+	for (i = 0; i < idl->nkeys; i++) {
+		if (idl->keys != NULL)
+			sshkey_free(idl->keys[i]);
+		if (idl->comments != NULL)
+			free(idl->comments[i]);
+	}
+	free(idl->keys);
+	free(idl->comments);
+	free(idl);
+}
+
+/*
+ * Check if the ssh agent has a given key.
+ * Returns 0 if found, or a negative SSH_ERR_* error code on failure.
+ */
+int
+ssh_agent_has_key(int sock, const struct sshkey *key)
+{
+	int r, ret = SSH_ERR_KEY_NOT_FOUND;
+	size_t i;
+	struct ssh_identitylist *idlist = NULL;
+
+	if ((r = ssh_fetch_identitylist(sock, &idlist)) != 0) {
+		return r;
+	}
+
+	for (i = 0; i < idlist->nkeys; i++) {
+		if (sshkey_equal_public(idlist->keys[i], key)) {
+			ret = 0;
+			break;
+		}
+	}
+
+	ssh_free_identitylist(idlist);
+	return ret;
+}
+
+/*
+ * Sends a challenge (typically from a server via ssh(1)) to the agent,
+ * and waits for a response from the agent.
+ * Returns true (non-zero) if the agent gave the correct answer, zero
+ * otherwise.
+ */
+
+
+/* encode signature algorithm in flag bits, so we can keep the msg format */
+static u_int
+agent_encode_alg(const struct sshkey *key, const char *alg)
+{
+	if (alg != NULL && sshkey_type_plain(key->type) == KEY_RSA) {
+		if (strcmp(alg, "rsa-sha2-256") == 0 ||
+		    strcmp(alg, "rsa-sha2-256-cert-v01@openssh.com") == 0)
+			return SSH_AGENT_RSA_SHA2_256;
+		if (strcmp(alg, "rsa-sha2-512") == 0 ||
+		    strcmp(alg, "rsa-sha2-512-cert-v01@openssh.com") == 0)
+			return SSH_AGENT_RSA_SHA2_512;
+	}
+	return 0;
+}
+
+/* ask agent to sign data, returns err.h code on error, 0 on success */
+int
+ssh_agent_sign(int sock, const struct sshkey *key,
+    u_char **sigp, size_t *lenp,
+    const u_char *data, size_t datalen, const char *alg, u_int compat)
+{
+	struct sshbuf *msg;
+	u_char *sig = NULL, type = 0;
+	size_t len = 0;
+	u_int flags = 0;
+	int r = SSH_ERR_INTERNAL_ERROR;
+
+	*sigp = NULL;
+	*lenp = 0;
+
+	if (datalen > SSH_KEY_MAX_SIGN_DATA_SIZE)
+		return SSH_ERR_INVALID_ARGUMENT;
+	if ((msg = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	flags |= agent_encode_alg(key, alg);
+	if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 ||
+	    (r = sshkey_puts(key, msg)) != 0 ||
+	    (r = sshbuf_put_string(msg, data, datalen)) != 0 ||
+	    (r = sshbuf_put_u32(msg, flags)) != 0)
+		goto out;
+	if ((r = ssh_request_reply(sock, msg, msg)) != 0)
+		goto out;
+	if ((r = sshbuf_get_u8(msg, &type)) != 0)
+		goto out;
+	if (agent_failed(type)) {
+		r = SSH_ERR_AGENT_FAILURE;
+		goto out;
+	} else if (type != SSH2_AGENT_SIGN_RESPONSE) {
+		r = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+	if ((r = sshbuf_get_string(msg, &sig, &len)) != 0)
+		goto out;
+	/* Check what we actually got back from the agent. */
+	if ((r = sshkey_check_sigtype(sig, len, alg)) != 0)
+		goto out;
+	/* success */
+	*sigp = sig;
+	*lenp = len;
+	sig = NULL;
+	len = 0;
+	r = 0;
+ out:
+	freezero(sig, len);
+	sshbuf_free(msg);
+	return r;
+}
+
+/* Encode key for a message to the agent. */
+
+static int
+encode_dest_constraint_hop(struct sshbuf *m,
+    const struct dest_constraint_hop *dch)
+{
+	struct sshbuf *b;
+	u_int i;
+	int r;
+
+	if ((b = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((r = sshbuf_put_cstring(b, dch->user)) != 0 ||
+	    (r = sshbuf_put_cstring(b, dch->hostname)) != 0 ||
+	    (r = sshbuf_put_string(b, NULL, 0)) != 0) /* reserved */
+		goto out;
+	for (i = 0; i < dch->nkeys; i++) {
+		if ((r = sshkey_puts(dch->keys[i], b)) != 0 ||
+		    (r = sshbuf_put_u8(b, dch->key_is_ca[i] != 0)) != 0)
+			goto out;
+	}
+	if ((r = sshbuf_put_stringb(m, b)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	sshbuf_free(b);
+	return r;
+}
+
+static int
+encode_dest_constraint(struct sshbuf *m, const struct dest_constraint *dc)
+{
+	struct sshbuf *b;
+	int r;
+
+	if ((b = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((r = encode_dest_constraint_hop(b, &dc->from)) != 0 ||
+	    (r = encode_dest_constraint_hop(b, &dc->to)) != 0 ||
+	    (r = sshbuf_put_string(b, NULL, 0)) != 0) /* reserved */
+		goto out;
+	if ((r = sshbuf_put_stringb(m, b)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	sshbuf_free(b);
+	return r;
+}
+
+static int
+encode_constraints(struct sshbuf *m, u_int life, u_int confirm,
+    u_int maxsign, const char *provider,
+    struct dest_constraint **dest_constraints, size_t ndest_constraints,
+    int cert_only, struct sshkey **certs, size_t ncerts)
+{
+	int r;
+	struct sshbuf *b = NULL;
+	size_t i;
+
+	if (life != 0) {
+		if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_LIFETIME)) != 0 ||
+		    (r = sshbuf_put_u32(m, life)) != 0)
+			goto out;
+	}
+	if (confirm != 0) {
+		if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_CONFIRM)) != 0)
+			goto out;
+	}
+	if (maxsign != 0) {
+		if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_MAXSIGN)) != 0 ||
+		    (r = sshbuf_put_u32(m, maxsign)) != 0)
+			goto out;
+	}
+	if (provider != NULL) {
+		if ((r = sshbuf_put_u8(m,
+		    SSH_AGENT_CONSTRAIN_EXTENSION)) != 0 ||
+		    (r = sshbuf_put_cstring(m,
+		    "sk-provider@openssh.com")) != 0 ||
+		    (r = sshbuf_put_cstring(m, provider)) != 0)
+			goto out;
+	}
+	if (dest_constraints != NULL && ndest_constraints > 0) {
+		if ((b = sshbuf_new()) == NULL) {
+			r = SSH_ERR_ALLOC_FAIL;
+			goto out;
+		}
+		for (i = 0; i < ndest_constraints; i++) {
+			if ((r = encode_dest_constraint(b,
+			    dest_constraints[i])) != 0)
+				goto out;
+		}
+		if ((r = sshbuf_put_u8(m,
+		    SSH_AGENT_CONSTRAIN_EXTENSION)) != 0 ||
+		    (r = sshbuf_put_cstring(m,
+		    "restrict-destination-v00@openssh.com")) != 0 ||
+		    (r = sshbuf_put_stringb(m, b)) != 0)
+			goto out;
+		sshbuf_free(b);
+		b = NULL;
+	}
+	if (ncerts != 0) {
+		if ((b = sshbuf_new()) == NULL) {
+			r = SSH_ERR_ALLOC_FAIL;
+			goto out;
+		}
+		for (i = 0; i < ncerts; i++) {
+			if ((r = sshkey_puts(certs[i], b)) != 0)
+				goto out;
+		}
+		if ((r = sshbuf_put_u8(m,
+		    SSH_AGENT_CONSTRAIN_EXTENSION)) != 0 ||
+		    (r = sshbuf_put_cstring(m,
+		    "associated-certs-v00@openssh.com")) != 0 ||
+		    (r = sshbuf_put_u8(m, cert_only != 0)) != 0 ||
+		    (r = sshbuf_put_stringb(m, b)) != 0)
+			goto out;
+		sshbuf_free(b);
+		b = NULL;
+	}
+	r = 0;
+ out:
+	sshbuf_free(b);
+	return r;
+}
+
+/*
+ * Adds an identity to the authentication server.
+ * This call is intended only for use by ssh-add(1) and like applications.
+ */
+int
+ssh_add_identity_constrained(int sock, struct sshkey *key,
+    const char *comment, u_int life, u_int confirm, u_int maxsign,
+    const char *provider, struct dest_constraint **dest_constraints,
+    size_t ndest_constraints)
+{
+	struct sshbuf *msg;
+	int r, constrained = (life || confirm || maxsign ||
+	    provider || dest_constraints);
+	u_char type;
+
+	if ((msg = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+
+	switch (key->type) {
+#ifdef WITH_OPENSSL
+	case KEY_RSA:
+	case KEY_RSA_CERT:
+	case KEY_DSA:
+	case KEY_DSA_CERT:
+	case KEY_ECDSA:
+	case KEY_ECDSA_CERT:
+	case KEY_ECDSA_SK:
+	case KEY_ECDSA_SK_CERT:
+#endif
+	case KEY_ED25519:
+	case KEY_ED25519_CERT:
+	case KEY_ED25519_SK:
+	case KEY_ED25519_SK_CERT:
+	case KEY_XMSS:
+	case KEY_XMSS_CERT:
+		type = constrained ?
+		    SSH2_AGENTC_ADD_ID_CONSTRAINED :
+		    SSH2_AGENTC_ADD_IDENTITY;
+		if ((r = sshbuf_put_u8(msg, type)) != 0 ||
+		    (r = sshkey_private_serialize_maxsign(key, msg, maxsign,
+		    0)) != 0 ||
+		    (r = sshbuf_put_cstring(msg, comment)) != 0)
+			goto out;
+		break;
+	default:
+		r = SSH_ERR_INVALID_ARGUMENT;
+		goto out;
+	}
+	if (constrained &&
+	    (r = encode_constraints(msg, life, confirm, maxsign,
+	    provider, dest_constraints, ndest_constraints, 0, NULL, 0)) != 0)
+		goto out;
+	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	sshbuf_free(msg);
+	return r;
+}
+
+/*
+ * Removes an identity from the authentication server.
+ * This call is intended only for use by ssh-add(1) and like applications.
+ */
+int
+ssh_remove_identity(int sock, const struct sshkey *key)
+{
+	struct sshbuf *msg;
+	int r;
+	u_char *blob = NULL;
+	size_t blen;
+
+	if ((msg = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+
+	if (key->type != KEY_UNSPEC) {
+		if ((r = sshkey_to_blob(key, &blob, &blen)) != 0)
+			goto out;
+		if ((r = sshbuf_put_u8(msg,
+		    SSH2_AGENTC_REMOVE_IDENTITY)) != 0 ||
+		    (r = sshbuf_put_string(msg, blob, blen)) != 0)
+			goto out;
+	} else {
+		r = SSH_ERR_INVALID_ARGUMENT;
+		goto out;
+	}
+	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	if (blob != NULL)
+		freezero(blob, blen);
+	sshbuf_free(msg);
+	return r;
+}
+
+/*
+ * Add/remove an token-based identity from the authentication server.
+ * This call is intended only for use by ssh-add(1) and like applications.
+ */
+int
+ssh_update_card(int sock, int add, const char *reader_id, const char *pin,
+    u_int life, u_int confirm,
+    struct dest_constraint **dest_constraints, size_t ndest_constraints,
+    int cert_only, struct sshkey **certs, size_t ncerts)
+{
+	struct sshbuf *msg;
+	int r, constrained = (life || confirm || dest_constraints || certs);
+	u_char type;
+
+	if (add) {
+		type = constrained ?
+		    SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
+		    SSH_AGENTC_ADD_SMARTCARD_KEY;
+	} else
+		type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
+
+	if ((msg = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((r = sshbuf_put_u8(msg, type)) != 0 ||
+	    (r = sshbuf_put_cstring(msg, reader_id)) != 0 ||
+	    (r = sshbuf_put_cstring(msg, pin)) != 0)
+		goto out;
+	if (constrained &&
+	    (r = encode_constraints(msg, life, confirm, 0, NULL,
+	    dest_constraints, ndest_constraints,
+	    cert_only, certs, ncerts)) != 0)
+		goto out;
+	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	sshbuf_free(msg);
+	return r;
+}
+
+/*
+ * Removes all identities from the agent.
+ * This call is intended only for use by ssh-add(1) and like applications.
+ *
+ * This supports the SSH protocol 1 message to because, when clearing all
+ * keys from an agent, we generally want to clear both protocol v1 and v2
+ * keys.
+ */
+int
+ssh_remove_all_identities(int sock, int version)
+{
+	struct sshbuf *msg;
+	u_char type = (version == 1) ?
+	    SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
+	    SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
+	int r;
+
+	if ((msg = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((r = sshbuf_put_u8(msg, type)) != 0)
+		goto out;
+	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	sshbuf_free(msg);
+	return r;
+}
+
+/* Binds a session ID to a hostkey via the initial KEX signature. */
+int
+ssh_agent_bind_hostkey(int sock, const struct sshkey *key,
+    const struct sshbuf *session_id, const struct sshbuf *signature,
+    int forwarding)
+{
+	struct sshbuf *msg;
+	int r;
+
+	if (key == NULL || session_id == NULL || signature == NULL)
+		return SSH_ERR_INVALID_ARGUMENT;
+	if ((msg = sshbuf_new()) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if ((r = sshbuf_put_u8(msg, SSH_AGENTC_EXTENSION)) != 0 ||
+	    (r = sshbuf_put_cstring(msg, "session-bind@openssh.com")) != 0 ||
+	    (r = sshkey_puts(key, msg)) != 0 ||
+	    (r = sshbuf_put_stringb(msg, session_id)) != 0 ||
+	    (r = sshbuf_put_stringb(msg, signature)) != 0 ||
+	    (r = sshbuf_put_u8(msg, forwarding ? 1 : 0)) != 0)
+		goto out;
+	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	sshbuf_free(msg);
+	return r;
+}