1 /* $OpenBSD: ssh-pkcs11-client.c,v 1.4 2013/05/17 00:13:14 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 free(blob);
125 send_msg(&msg);
126 buffer_clear(&msg);
127
128 if (recv_msg(&msg) == SSH2_AGENT_SIGN_RESPONSE) {
129 signature = buffer_get_string(&msg, &slen);
130 if (slen <= (u_int)RSA_size(rsa)) {
131 memcpy(to, signature, slen);
132 ret = slen;
133 }
134 free(signature);
135 }
136 buffer_free(&msg);
137 return (ret);
138 }
139
140 /* redirect the private key encrypt operation to the ssh-pkcs11-helper */
141 static int
wrap_key(RSA * rsa)142 wrap_key(RSA *rsa)
143 {
144 static RSA_METHOD helper_rsa;
145
146 memcpy(&helper_rsa, RSA_get_default_method(), sizeof(helper_rsa));
147 helper_rsa.name = "ssh-pkcs11-helper";
148 helper_rsa.rsa_priv_enc = pkcs11_rsa_private_encrypt;
149 RSA_set_method(rsa, &helper_rsa);
150 return (0);
151 }
152
153 static int
pkcs11_start_helper(void)154 pkcs11_start_helper(void)
155 {
156 int pair[2];
157
158 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
159 error("socketpair: %s", strerror(errno));
160 return (-1);
161 }
162 if ((pid = fork()) == -1) {
163 error("fork: %s", strerror(errno));
164 return (-1);
165 } else if (pid == 0) {
166 if ((dup2(pair[1], STDIN_FILENO) == -1) ||
167 (dup2(pair[1], STDOUT_FILENO) == -1)) {
168 fprintf(stderr, "dup2: %s\n", strerror(errno));
169 _exit(1);
170 }
171 close(pair[0]);
172 close(pair[1]);
173 execlp(_PATH_SSH_PKCS11_HELPER, _PATH_SSH_PKCS11_HELPER,
174 (char *) 0);
175 fprintf(stderr, "exec: %s: %s\n", _PATH_SSH_PKCS11_HELPER,
176 strerror(errno));
177 _exit(1);
178 }
179 close(pair[1]);
180 fd = pair[0];
181 return (0);
182 }
183
184 int
pkcs11_add_provider(char * name,char * pin,Key *** keysp)185 pkcs11_add_provider(char *name, char *pin, Key ***keysp)
186 {
187 Key *k;
188 int i, nkeys;
189 u_char *blob;
190 u_int blen;
191 Buffer msg;
192
193 if (fd < 0 && pkcs11_start_helper() < 0)
194 return (-1);
195
196 buffer_init(&msg);
197 buffer_put_char(&msg, SSH_AGENTC_ADD_SMARTCARD_KEY);
198 buffer_put_cstring(&msg, name);
199 buffer_put_cstring(&msg, pin);
200 send_msg(&msg);
201 buffer_clear(&msg);
202
203 if (recv_msg(&msg) == SSH2_AGENT_IDENTITIES_ANSWER) {
204 nkeys = buffer_get_int(&msg);
205 *keysp = xcalloc(nkeys, sizeof(Key *));
206 for (i = 0; i < nkeys; i++) {
207 blob = buffer_get_string(&msg, &blen);
208 free(buffer_get_string(&msg, NULL));
209 k = key_from_blob(blob, blen);
210 wrap_key(k->rsa);
211 (*keysp)[i] = k;
212 free(blob);
213 }
214 } else {
215 nkeys = -1;
216 }
217 buffer_free(&msg);
218 return (nkeys);
219 }
220
221 int
pkcs11_del_provider(char * name)222 pkcs11_del_provider(char *name)
223 {
224 int ret = -1;
225 Buffer msg;
226
227 buffer_init(&msg);
228 buffer_put_char(&msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY);
229 buffer_put_cstring(&msg, name);
230 buffer_put_cstring(&msg, "");
231 send_msg(&msg);
232 buffer_clear(&msg);
233
234 if (recv_msg(&msg) == SSH_AGENT_SUCCESS)
235 ret = 0;
236 buffer_free(&msg);
237 return (ret);
238 }
239
240 #endif /* ENABLE_PKCS11 */
241