1 /* $OpenBSD: ssh-pkcs11-client.c,v 1.10 2018/07/09 21:59:10 markus 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 <openssl/rsa.h> 34 35 #include "pathnames.h" 36 #include "xmalloc.h" 37 #include "sshbuf.h" 38 #include "log.h" 39 #include "misc.h" 40 #include "sshkey.h" 41 #include "authfd.h" 42 #include "atomicio.h" 43 #include "ssh-pkcs11.h" 44 #include "ssherr.h" 45 46 /* borrows code from sftp-server and ssh-agent */ 47 48 int fd = -1; 49 pid_t pid = -1; 50 51 static void 52 send_msg(struct sshbuf *m) 53 { 54 u_char buf[4]; 55 size_t mlen = sshbuf_len(m); 56 int r; 57 58 POKE_U32(buf, mlen); 59 if (atomicio(vwrite, fd, buf, 4) != 4 || 60 atomicio(vwrite, fd, sshbuf_mutable_ptr(m), 61 sshbuf_len(m)) != sshbuf_len(m)) 62 error("write to helper failed"); 63 if ((r = sshbuf_consume(m, mlen)) != 0) 64 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 65 } 66 67 static int 68 recv_msg(struct sshbuf *m) 69 { 70 u_int l, len; 71 u_char c, buf[1024]; 72 int r; 73 74 if ((len = atomicio(read, fd, buf, 4)) != 4) { 75 error("read from helper failed: %u", len); 76 return (0); /* XXX */ 77 } 78 len = PEEK_U32(buf); 79 if (len > 256 * 1024) 80 fatal("response too long: %u", len); 81 /* read len bytes into m */ 82 sshbuf_reset(m); 83 while (len > 0) { 84 l = len; 85 if (l > sizeof(buf)) 86 l = sizeof(buf); 87 if (atomicio(read, fd, buf, l) != l) { 88 error("response from helper failed."); 89 return (0); /* XXX */ 90 } 91 if ((r = sshbuf_put(m, buf, l)) != 0) 92 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 93 len -= l; 94 } 95 if ((r = sshbuf_get_u8(m, &c)) != 0) 96 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 97 return c; 98 } 99 100 int 101 pkcs11_init(int interactive) 102 { 103 return (0); 104 } 105 106 void 107 pkcs11_terminate(void) 108 { 109 if (fd >= 0) 110 close(fd); 111 } 112 113 static int 114 pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa, 115 int padding) 116 { 117 struct sshkey key; /* XXX */ 118 u_char *blob, *signature = NULL; 119 size_t blen, slen = 0; 120 int r, ret = -1; 121 struct sshbuf *msg; 122 123 if (padding != RSA_PKCS1_PADDING) 124 return (-1); 125 key.type = KEY_RSA; 126 key.rsa = rsa; 127 if ((r = sshkey_to_blob(&key, &blob, &blen)) != 0) { 128 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 129 return -1; 130 } 131 if ((msg = sshbuf_new()) == NULL) 132 fatal("%s: sshbuf_new failed", __func__); 133 if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 || 134 (r = sshbuf_put_string(msg, blob, blen)) != 0 || 135 (r = sshbuf_put_string(msg, from, flen)) != 0 || 136 (r = sshbuf_put_u32(msg, 0)) != 0) 137 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 138 free(blob); 139 send_msg(msg); 140 sshbuf_reset(msg); 141 142 if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) { 143 if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0) 144 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 145 if (slen <= (size_t)RSA_size(rsa)) { 146 memcpy(to, signature, slen); 147 ret = slen; 148 } 149 free(signature); 150 } 151 sshbuf_free(msg); 152 return (ret); 153 } 154 155 /* redirect the private key encrypt operation to the ssh-pkcs11-helper */ 156 static int 157 wrap_key(RSA *rsa) 158 { 159 static RSA_METHOD helper_rsa; 160 161 memcpy(&helper_rsa, RSA_get_default_method(), sizeof(helper_rsa)); 162 helper_rsa.name = "ssh-pkcs11-helper"; 163 helper_rsa.rsa_priv_enc = pkcs11_rsa_private_encrypt; 164 RSA_set_method(rsa, &helper_rsa); 165 return (0); 166 } 167 168 static int 169 pkcs11_start_helper(void) 170 { 171 int pair[2]; 172 173 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) { 174 error("socketpair: %s", strerror(errno)); 175 return (-1); 176 } 177 if ((pid = fork()) == -1) { 178 error("fork: %s", strerror(errno)); 179 return (-1); 180 } else if (pid == 0) { 181 if ((dup2(pair[1], STDIN_FILENO) == -1) || 182 (dup2(pair[1], STDOUT_FILENO) == -1)) { 183 fprintf(stderr, "dup2: %s\n", strerror(errno)); 184 _exit(1); 185 } 186 close(pair[0]); 187 close(pair[1]); 188 execlp(_PATH_SSH_PKCS11_HELPER, _PATH_SSH_PKCS11_HELPER, 189 (char *)NULL); 190 fprintf(stderr, "exec: %s: %s\n", _PATH_SSH_PKCS11_HELPER, 191 strerror(errno)); 192 _exit(1); 193 } 194 close(pair[1]); 195 fd = pair[0]; 196 return (0); 197 } 198 199 int 200 pkcs11_add_provider(char *name, char *pin, struct sshkey ***keysp) 201 { 202 struct sshkey *k; 203 int r; 204 u_char *blob; 205 size_t blen; 206 u_int nkeys, i; 207 struct sshbuf *msg; 208 209 if (fd < 0 && pkcs11_start_helper() < 0) 210 return (-1); 211 212 if ((msg = sshbuf_new()) == NULL) 213 fatal("%s: sshbuf_new failed", __func__); 214 if ((r = sshbuf_put_u8(msg, SSH_AGENTC_ADD_SMARTCARD_KEY)) != 0 || 215 (r = sshbuf_put_cstring(msg, name)) != 0 || 216 (r = sshbuf_put_cstring(msg, pin)) != 0) 217 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 218 send_msg(msg); 219 sshbuf_reset(msg); 220 221 if (recv_msg(msg) == SSH2_AGENT_IDENTITIES_ANSWER) { 222 if ((r = sshbuf_get_u32(msg, &nkeys)) != 0) 223 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 224 *keysp = xcalloc(nkeys, sizeof(struct sshkey *)); 225 for (i = 0; i < nkeys; i++) { 226 /* XXX clean up properly instead of fatal() */ 227 if ((r = sshbuf_get_string(msg, &blob, &blen)) != 0 || 228 (r = sshbuf_skip_string(msg)) != 0) 229 fatal("%s: buffer error: %s", 230 __func__, ssh_err(r)); 231 if ((r = sshkey_from_blob(blob, blen, &k)) != 0) 232 fatal("%s: bad key: %s", __func__, ssh_err(r)); 233 wrap_key(k->rsa); 234 (*keysp)[i] = k; 235 free(blob); 236 } 237 } else { 238 nkeys = -1; 239 } 240 sshbuf_free(msg); 241 return (nkeys); 242 } 243 244 int 245 pkcs11_del_provider(char *name) 246 { 247 int r, ret = -1; 248 struct sshbuf *msg; 249 250 if ((msg = sshbuf_new()) == NULL) 251 fatal("%s: sshbuf_new failed", __func__); 252 if ((r = sshbuf_put_u8(msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY)) != 0 || 253 (r = sshbuf_put_cstring(msg, name)) != 0 || 254 (r = sshbuf_put_cstring(msg, "")) != 0) 255 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 256 send_msg(msg); 257 sshbuf_reset(msg); 258 259 if (recv_msg(msg) == SSH_AGENT_SUCCESS) 260 ret = 0; 261 sshbuf_free(msg); 262 return (ret); 263 } 264 265 #endif /* ENABLE_PKCS11 */ 266