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-rw-r--r--libssh/src/agent.c516
1 files changed, 516 insertions, 0 deletions
diff --git a/libssh/src/agent.c b/libssh/src/agent.c
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+++ b/libssh/src/agent.c
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+/*
+ * agent.c - ssh agent functions
+ *
+ * This file is part of the SSH Library
+ *
+ * Copyright (c) 2008-2009 by Andreas Schneider <asn@cryptomilk.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/* This file is based on authfd.c from OpenSSH */
+
+/*
+ * How does the ssh-agent work?
+ *
+ * a) client sends a request to get a list of all keys
+ * the agent returns the count and all public keys
+ * b) iterate over them to check if the server likes one
+ * c) the client sends a sign request to the agent
+ * type, pubkey as blob, data to sign, flags
+ * the agent returns the signed data
+ */
+
+#ifndef _WIN32
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+
+#include <unistd.h>
+
+#ifndef _WIN32
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#endif
+
+#include "libssh/agent.h"
+#include "libssh/priv.h"
+#include "libssh/socket.h"
+#include "libssh/buffer.h"
+#include "libssh/session.h"
+#include "libssh/poll.h"
+#include "libssh/pki.h"
+
+/* macro to check for "agent failure" message */
+#define agent_failed(x) \
+ (((x) == SSH_AGENT_FAILURE) || ((x) == SSH_COM_AGENT2_FAILURE) || \
+ ((x) == SSH2_AGENT_FAILURE))
+
+static uint32_t agent_get_u32(const void *vp) {
+ const uint8_t *p = (const uint8_t *)vp;
+ uint32_t v;
+
+ v = (uint32_t)p[0] << 24;
+ v |= (uint32_t)p[1] << 16;
+ v |= (uint32_t)p[2] << 8;
+ v |= (uint32_t)p[3];
+
+ return v;
+}
+
+static void agent_put_u32(void *vp, uint32_t v) {
+ uint8_t *p = (uint8_t *)vp;
+
+ p[0] = (uint8_t)(v >> 24) & 0xff;
+ p[1] = (uint8_t)(v >> 16) & 0xff;
+ p[2] = (uint8_t)(v >> 8) & 0xff;
+ p[3] = (uint8_t)v & 0xff;
+}
+
+static size_t atomicio(ssh_socket s, void *buf, size_t n, int do_read) {
+ char *b = buf;
+ size_t pos = 0;
+ ssize_t res;
+ ssh_pollfd_t pfd;
+ socket_t fd = ssh_socket_get_fd_in(s);
+
+ pfd.fd = fd;
+ pfd.events = do_read ? POLLIN : POLLOUT;
+
+ while (n > pos) {
+ if (do_read) {
+ res = read(fd, b + pos, n - pos);
+ } else {
+ res = write(fd, b + pos, n - pos);
+ }
+ switch (res) {
+ case -1:
+ if (errno == EINTR) {
+ continue;
+ }
+#ifdef EWOULDBLOCK
+ if (errno == EAGAIN || errno == EWOULDBLOCK) {
+#else
+ if (errno == EAGAIN) {
+#endif
+ (void) ssh_poll(&pfd, 1, -1);
+ continue;
+ }
+ return 0;
+ case 0:
+ /* read returns 0 on end-of-file */
+ errno = do_read ? 0 : EPIPE;
+ return pos;
+ default:
+ pos += (size_t) res;
+ }
+ }
+
+ return pos;
+}
+
+ssh_agent agent_new(struct ssh_session_struct *session) {
+ ssh_agent agent = NULL;
+
+ agent = malloc(sizeof(struct ssh_agent_struct));
+ if (agent == NULL) {
+ return NULL;
+ }
+ ZERO_STRUCTP(agent);
+
+ agent->count = 0;
+ agent->sock = ssh_socket_new(session);
+ if (agent->sock == NULL) {
+ SAFE_FREE(agent);
+ return NULL;
+ }
+
+ return agent;
+}
+
+void agent_close(struct ssh_agent_struct *agent) {
+ if (agent == NULL) {
+ return;
+ }
+
+ if (getenv("SSH_AUTH_SOCK")) {
+ ssh_socket_close(agent->sock);
+ }
+}
+
+void agent_free(ssh_agent agent) {
+ if (agent) {
+ if (agent->ident) {
+ ssh_buffer_free(agent->ident);
+ }
+ if (agent->sock) {
+ agent_close(agent);
+ ssh_socket_free(agent->sock);
+ }
+ SAFE_FREE(agent);
+ }
+}
+
+static int agent_connect(ssh_session session) {
+ const char *auth_sock = NULL;
+
+ if (session == NULL || session->agent == NULL) {
+ return -1;
+ }
+
+ auth_sock = getenv("SSH_AUTH_SOCK");
+
+ if (auth_sock && *auth_sock) {
+ if (ssh_socket_unix(session->agent->sock, auth_sock) < 0) {
+ return -1;
+ }
+ return 0;
+ }
+
+ return -1;
+}
+
+#if 0
+static int agent_decode_reply(struct ssh_session_struct *session, int type) {
+ switch (type) {
+ case SSH_AGENT_FAILURE:
+ case SSH2_AGENT_FAILURE:
+ case SSH_COM_AGENT2_FAILURE:
+ ssh_log(session, SSH_LOG_RARE, "SSH_AGENT_FAILURE");
+ return 0;
+ case SSH_AGENT_SUCCESS:
+ return 1;
+ default:
+ ssh_set_error(session, SSH_FATAL,
+ "Bad response from authentication agent: %d", type);
+ break;
+ }
+
+ return -1;
+}
+#endif
+
+static int agent_talk(struct ssh_session_struct *session,
+ struct ssh_buffer_struct *request, struct ssh_buffer_struct *reply) {
+ uint32_t len = 0;
+ uint8_t payload[1024] = {0};
+
+ len = buffer_get_rest_len(request);
+ SSH_LOG(session, SSH_LOG_TRACE, "Request length: %u", len);
+ agent_put_u32(payload, len);
+
+ /* send length and then the request packet */
+ if (atomicio(session->agent->sock, payload, 4, 0) == 4) {
+ if (atomicio(session->agent->sock, buffer_get_rest(request), len, 0)
+ != len) {
+ SSH_LOG(session, SSH_LOG_WARN, "atomicio sending request failed: %s",
+ strerror(errno));
+ return -1;
+ }
+ } else {
+ SSH_LOG(session, SSH_LOG_WARN,
+ "atomicio sending request length failed: %s",
+ strerror(errno));
+ return -1;
+ }
+
+ /* wait for response, read the length of the response packet */
+ if (atomicio(session->agent->sock, payload, 4, 1) != 4) {
+ SSH_LOG(session, SSH_LOG_WARN, "atomicio read response length failed: %s",
+ strerror(errno));
+ return -1;
+ }
+
+ len = agent_get_u32(payload);
+ if (len > 256 * 1024) {
+ ssh_set_error(session, SSH_FATAL,
+ "Authentication response too long: %u", len);
+ return -1;
+ }
+ SSH_LOG(session, SSH_LOG_TRACE, "Response length: %u", len);
+
+ while (len > 0) {
+ size_t n = len;
+ if (n > sizeof(payload)) {
+ n = sizeof(payload);
+ }
+ if (atomicio(session->agent->sock, payload, n, 1) != n) {
+ SSH_LOG(session, SSH_LOG_WARN,
+ "Error reading response from authentication socket.");
+ return -1;
+ }
+ if (buffer_add_data(reply, payload, n) < 0) {
+ SSH_LOG(session, SSH_LOG_WARN, "Not enough space");
+ return -1;
+ }
+ len -= n;
+ }
+
+ return 0;
+}
+
+int ssh_agent_get_ident_count(struct ssh_session_struct *session) {
+ ssh_buffer request = NULL;
+ ssh_buffer reply = NULL;
+ unsigned int type = 0;
+ unsigned int c1 = 0, c2 = 0;
+ uint8_t buf[4] = {0};
+
+ switch (session->version) {
+ case 1:
+ c1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
+ c2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
+ break;
+ case 2:
+ c1 = SSH2_AGENTC_REQUEST_IDENTITIES;
+ c2 = SSH2_AGENT_IDENTITIES_ANSWER;
+ break;
+ default:
+ return 0;
+ }
+
+ /* send message to the agent requesting the list of identities */
+ request = ssh_buffer_new();
+ if (buffer_add_u8(request, c1) < 0) {
+ ssh_set_error(session, SSH_FATAL, "Not enough space");
+ return -1;
+ }
+
+ reply = ssh_buffer_new();
+ if (reply == NULL) {
+ ssh_buffer_free(request);
+ ssh_set_error(session, SSH_FATAL, "Not enough space");
+ return -1;
+ }
+
+ if (agent_talk(session, request, reply) < 0) {
+ ssh_buffer_free(request);
+ ssh_buffer_free(reply);
+ return 0;
+ }
+ ssh_buffer_free(request);
+
+ /* get message type and verify the answer */
+ buffer_get_u8(reply, (uint8_t *) &type);
+ SSH_LOG(session, SSH_LOG_WARN,
+ "Answer type: %d, expected answer: %d",
+ type, c2);
+ if (agent_failed(type)) {
+ return 0;
+ } else if (type != c2) {
+ ssh_set_error(session, SSH_FATAL,
+ "Bad authentication reply message type: %d", type);
+ return -1;
+ }
+
+ buffer_get_u32(reply, (uint32_t *) buf);
+ session->agent->count = agent_get_u32(buf);
+ SSH_LOG(session, SSH_LOG_DEBUG, "Agent count: %d",
+ session->agent->count);
+ if (session->agent->count > 1024) {
+ ssh_set_error(session, SSH_FATAL,
+ "Too many identities in authentication reply: %d",
+ session->agent->count);
+ ssh_buffer_free(reply);
+ return -1;
+ }
+
+ if (session->agent->ident) {
+ buffer_reinit(session->agent->ident);
+ }
+ session->agent->ident = reply;
+
+ return session->agent->count;
+}
+
+/* caller has to free commment */
+ssh_key ssh_agent_get_first_ident(struct ssh_session_struct *session,
+ char **comment) {
+ if (ssh_agent_get_ident_count(session) > 0) {
+ return ssh_agent_get_next_ident(session, comment);
+ }
+
+ return NULL;
+}
+
+/* caller has to free commment */
+ssh_key ssh_agent_get_next_ident(struct ssh_session_struct *session,
+ char **comment) {
+ struct ssh_key_struct *key;
+ struct ssh_string_struct *blob = NULL;
+ struct ssh_string_struct *tmp = NULL;
+ int rc;
+
+ if (session->agent->count == 0) {
+ return NULL;
+ }
+
+ switch(session->version) {
+ case 1:
+ return NULL;
+ case 2:
+ /* get the blob */
+ blob = buffer_get_ssh_string(session->agent->ident);
+ if (blob == NULL) {
+ return NULL;
+ }
+
+ /* get the comment */
+ tmp = buffer_get_ssh_string(session->agent->ident);
+ if (tmp == NULL) {
+ ssh_string_free(blob);
+
+ return NULL;
+ }
+
+ if (comment) {
+ *comment = ssh_string_to_char(tmp);
+ } else {
+ ssh_string_free(blob);
+ ssh_string_free(tmp);
+
+ return NULL;
+ }
+ ssh_string_free(tmp);
+
+ /* get key from blob */
+ rc = ssh_pki_import_pubkey_blob(blob, &key);
+ ssh_string_free(blob);
+ if (rc == SSH_ERROR) {
+ return NULL;
+ }
+ break;
+ default:
+ return NULL;
+ }
+
+ return key;
+}
+
+int agent_is_running(ssh_session session) {
+ if (session == NULL || session->agent == NULL) {
+ return 0;
+ }
+
+ if (ssh_socket_is_open(session->agent->sock)) {
+ return 1;
+ } else {
+ if (agent_connect(session) < 0) {
+ return 0;
+ } else {
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+ssh_string ssh_agent_sign_data(ssh_session session,
+ const ssh_key pubkey,
+ struct ssh_buffer_struct *data)
+{
+ ssh_buffer request;
+ ssh_buffer reply;
+ ssh_string key_blob;
+ ssh_string sig_blob;
+ int type = SSH2_AGENT_FAILURE;
+ int flags = 0;
+ uint32_t dlen;
+ int rc;
+
+ request = ssh_buffer_new();
+ if (request == NULL) {
+ return NULL;
+ }
+
+ /* create request */
+ if (buffer_add_u8(request, SSH2_AGENTC_SIGN_REQUEST) < 0) {
+ ssh_buffer_free(request);
+ return NULL;
+ }
+
+ rc = ssh_pki_export_pubkey_blob(pubkey, &key_blob);
+ if (rc < 0) {
+ ssh_buffer_free(request);
+ return NULL;
+ }
+
+ /* adds len + blob */
+ rc = buffer_add_ssh_string(request, key_blob);
+ ssh_string_free(key_blob);
+ if (rc < 0) {
+ ssh_buffer_free(request);
+ return NULL;
+ }
+
+ /* Add data */
+ dlen = buffer_get_rest_len(data);
+ if (buffer_add_u32(request, htonl(dlen)) < 0) {
+ ssh_buffer_free(request);
+ return NULL;
+ }
+ if (buffer_add_data(request, buffer_get_rest(data), dlen) < 0) {
+ ssh_buffer_free(request);
+ return NULL;
+ }
+
+ if (buffer_add_u32(request, htonl(flags)) < 0) {
+ ssh_buffer_free(request);
+ return NULL;
+ }
+
+ reply = ssh_buffer_new();
+ if (reply == NULL) {
+ ssh_buffer_free(request);
+ return NULL;
+ }
+
+ /* send the request */
+ if (agent_talk(session, request, reply) < 0) {
+ ssh_buffer_free(request);
+ ssh_buffer_free(reply);
+ return NULL;
+ }
+ ssh_buffer_free(request);
+
+ /* check if reply is valid */
+ if (buffer_get_u8(reply, (uint8_t *) &type) != sizeof(uint8_t)) {
+ ssh_buffer_free(reply);
+ return NULL;
+ }
+
+ if (agent_failed(type)) {
+ SSH_LOG(session, SSH_LOG_WARN, "Agent reports failure in signing the key");
+ ssh_buffer_free(reply);
+ return NULL;
+ } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
+ ssh_set_error(session, SSH_FATAL, "Bad authentication response: %d", type);
+ ssh_buffer_free(reply);
+ return NULL;
+ }
+
+ sig_blob = buffer_get_ssh_string(reply);
+ ssh_buffer_free(reply);
+
+ return sig_blob;
+}
+
+#endif /* _WIN32 */
+
+/* vim: set ts=4 sw=4 et cindent: */
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