1 /* $OpenBSD: ssh-pkcs11-client.c,v 1.2 2010/02/24 06:12:53 djm Exp $ */
2 /*
3 * Copyright (c) 2010 Markus Friedl. All rights reserved.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include "includes.h"
19
20 #ifdef ENABLE_PKCS11
21
22 #include <sys/types.h>
23 #ifdef HAVE_SYS_TIME_H
24 # include <sys/time.h>
25 #endif
26 #include <sys/socket.h>
27
28 #include <stdarg.h>
29 #include <string.h>
30 #include <unistd.h>
31 #include <errno.h>
32
33 #include "pathnames.h"
34 #include "xmalloc.h"
35 #include "buffer.h"
36 #include "log.h"
37 #include "misc.h"
38 #include "key.h"
39 #include "authfd.h"
40 #include "atomicio.h"
41 #include "ssh-pkcs11.h"
42
43 /* borrows code from sftp-server and ssh-agent */
44
45 int fd = -1;
46 pid_t pid = -1;
47
48 static void
send_msg(Buffer * m)49 send_msg(Buffer *m)
50 {
51 u_char buf[4];
52 int mlen = buffer_len(m);
53
54 put_u32(buf, mlen);
55 if (atomicio(vwrite, fd, buf, 4) != 4 ||
56 atomicio(vwrite, fd, buffer_ptr(m),
57 buffer_len(m)) != buffer_len(m))
58 error("write to helper failed");
59 buffer_consume(m, mlen);
60 }
61
62 static int
recv_msg(Buffer * m)63 recv_msg(Buffer *m)
64 {
65 u_int l, len;
66 u_char buf[1024];
67
68 if ((len = atomicio(read, fd, buf, 4)) != 4) {
69 error("read from helper failed: %u", len);
70 return (0); /* XXX */
71 }
72 len = get_u32(buf);
73 if (len > 256 * 1024)
74 fatal("response too long: %u", len);
75 /* read len bytes into m */
76 buffer_clear(m);
77 while (len > 0) {
78 l = len;
79 if (l > sizeof(buf))
80 l = sizeof(buf);
81 if (atomicio(read, fd, buf, l) != l) {
82 error("response from helper failed.");
83 return (0); /* XXX */
84 }
85 buffer_append(m, buf, l);
86 len -= l;
87 }
88 return (buffer_get_char(m));
89 }
90
91 int
pkcs11_init(int interactive)92 pkcs11_init(int interactive)
93 {
94 return (0);
95 }
96
97 void
pkcs11_terminate(void)98 pkcs11_terminate(void)
99 {
100 close(fd);
101 }
102
103 static int
pkcs11_rsa_private_encrypt(int flen,const u_char * from,u_char * to,RSA * rsa,int padding)104 pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
105 int padding)
106 {
107 Key key;
108 u_char *blob, *signature = NULL;
109 u_int blen, slen = 0;
110 int ret = -1;
111 Buffer msg;
112
113 if (padding != RSA_PKCS1_PADDING)
114 return (-1);
115 key.type = KEY_RSA;
116 key.rsa = rsa;
117 if (key_to_blob(&key, &blob, &blen) == 0)
118 return -1;
119 buffer_init(&msg);
120 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
121 buffer_put_string(&msg, blob, blen);
122 buffer_put_string(&msg, from, flen);
123 buffer_put_int(&msg, 0);
124 xfree(blob);
125 send_msg(&msg);
126
127 if (recv_msg(&msg) == SSH2_AGENT_SIGN_RESPONSE) {
128 signature = buffer_get_string(&msg, &slen);
129 if (slen <= (u_int)RSA_size(rsa)) {
130 memcpy(to, signature, slen);
131 ret = slen;
132 }
133 xfree(signature);
134 }
135 return (ret);
136 }
137
138 /* redirect the private key encrypt operation to the ssh-pkcs11-helper */
139 static int
wrap_key(RSA * rsa)140 wrap_key(RSA *rsa)
141 {
142 static RSA_METHOD helper_rsa;
143
144 memcpy(&helper_rsa, RSA_get_default_method(), sizeof(helper_rsa));
145 helper_rsa.name = "ssh-pkcs11-helper";
146 helper_rsa.rsa_priv_enc = pkcs11_rsa_private_encrypt;
147 RSA_set_method(rsa, &helper_rsa);
148 return (0);
149 }
150
151 static int
pkcs11_start_helper(void)152 pkcs11_start_helper(void)
153 {
154 int pair[2];
155
156 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
157 error("socketpair: %s", strerror(errno));
158 return (-1);
159 }
160 if ((pid = fork()) == -1) {
161 error("fork: %s", strerror(errno));
162 return (-1);
163 } else if (pid == 0) {
164 if ((dup2(pair[1], STDIN_FILENO) == -1) ||
165 (dup2(pair[1], STDOUT_FILENO) == -1)) {
166 fprintf(stderr, "dup2: %s\n", strerror(errno));
167 _exit(1);
168 }
169 close(pair[0]);
170 close(pair[1]);
171 execlp(_PATH_SSH_PKCS11_HELPER, _PATH_SSH_PKCS11_HELPER,
172 (char *) 0);
173 fprintf(stderr, "exec: %s: %s\n", _PATH_SSH_PKCS11_HELPER,
174 strerror(errno));
175 _exit(1);
176 }
177 close(pair[1]);
178 fd = pair[0];
179 return (0);
180 }
181
182 int
pkcs11_add_provider(char * name,char * pin,Key *** keysp)183 pkcs11_add_provider(char *name, char *pin, Key ***keysp)
184 {
185 Key *k;
186 int i, nkeys;
187 u_char *blob;
188 u_int blen;
189 Buffer msg;
190
191 if (fd < 0 && pkcs11_start_helper() < 0)
192 return (-1);
193
194 buffer_init(&msg);
195 buffer_put_char(&msg, SSH_AGENTC_ADD_SMARTCARD_KEY);
196 buffer_put_cstring(&msg, name);
197 buffer_put_cstring(&msg, pin);
198 send_msg(&msg);
199 buffer_clear(&msg);
200
201 if (recv_msg(&msg) == SSH2_AGENT_IDENTITIES_ANSWER) {
202 nkeys = buffer_get_int(&msg);
203 *keysp = xcalloc(nkeys, sizeof(Key *));
204 for (i = 0; i < nkeys; i++) {
205 blob = buffer_get_string(&msg, &blen);
206 xfree(buffer_get_string(&msg, NULL));
207 k = key_from_blob(blob, blen);
208 wrap_key(k->rsa);
209 (*keysp)[i] = k;
210 xfree(blob);
211 }
212 } else {
213 nkeys = -1;
214 }
215 buffer_free(&msg);
216 return (nkeys);
217 }
218
219 int
pkcs11_del_provider(char * name)220 pkcs11_del_provider(char *name)
221 {
222 int ret = -1;
223 Buffer msg;
224
225 buffer_init(&msg);
226 buffer_put_char(&msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY);
227 buffer_put_cstring(&msg, name);
228 buffer_put_cstring(&msg, "");
229 send_msg(&msg);
230 buffer_clear(&msg);
231
232 if (recv_msg(&msg) == SSH_AGENT_SUCCESS)
233 ret = 0;
234 buffer_free(&msg);
235 return (ret);
236 }
237
238 #endif /* ENABLE_PKCS11 */
239