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 "openbsd-compat/openssl-compat.h" 36 37 #include "pathnames.h" 38 #include "xmalloc.h" 39 #include "sshbuf.h" 40 #include "log.h" 41 #include "misc.h" 42 #include "sshkey.h" 43 #include "authfd.h" 44 #include "atomicio.h" 45 #include "ssh-pkcs11.h" 46 #include "ssherr.h" 47 48 /* borrows code from sftp-server and ssh-agent */ 49 50 int fd = -1; 51 pid_t pid = -1; 52 53 static void 54 send_msg(struct sshbuf *m) 55 { 56 u_char buf[4]; 57 size_t mlen = sshbuf_len(m); 58 int r; 59 60 POKE_U32(buf, mlen); 61 if (atomicio(vwrite, fd, buf, 4) != 4 || 62 atomicio(vwrite, fd, sshbuf_mutable_ptr(m), 63 sshbuf_len(m)) != sshbuf_len(m)) 64 error("write to helper failed"); 65 if ((r = sshbuf_consume(m, mlen)) != 0) 66 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 67 } 68 69 static int 70 recv_msg(struct sshbuf *m) 71 { 72 u_int l, len; 73 u_char c, buf[1024]; 74 int r; 75 76 if ((len = atomicio(read, fd, buf, 4)) != 4) { 77 error("read from helper failed: %u", len); 78 return (0); /* XXX */ 79 } 80 len = PEEK_U32(buf); 81 if (len > 256 * 1024) 82 fatal("response too long: %u", len); 83 /* read len bytes into m */ 84 sshbuf_reset(m); 85 while (len > 0) { 86 l = len; 87 if (l > sizeof(buf)) 88 l = sizeof(buf); 89 if (atomicio(read, fd, buf, l) != l) { 90 error("response from helper failed."); 91 return (0); /* XXX */ 92 } 93 if ((r = sshbuf_put(m, buf, l)) != 0) 94 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 95 len -= l; 96 } 97 if ((r = sshbuf_get_u8(m, &c)) != 0) 98 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 99 return c; 100 } 101 102 int 103 pkcs11_init(int interactive) 104 { 105 return (0); 106 } 107 108 void 109 pkcs11_terminate(void) 110 { 111 if (fd >= 0) 112 close(fd); 113 } 114 115 static int 116 pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa, 117 int padding) 118 { 119 struct sshkey key; /* XXX */ 120 u_char *blob, *signature = NULL; 121 size_t blen, slen = 0; 122 int r, ret = -1; 123 struct sshbuf *msg; 124 125 if (padding != RSA_PKCS1_PADDING) 126 return (-1); 127 key.type = KEY_RSA; 128 key.rsa = rsa; 129 if ((r = sshkey_to_blob(&key, &blob, &blen)) != 0) { 130 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); 131 return -1; 132 } 133 if ((msg = sshbuf_new()) == NULL) 134 fatal("%s: sshbuf_new failed", __func__); 135 if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 || 136 (r = sshbuf_put_string(msg, blob, blen)) != 0 || 137 (r = sshbuf_put_string(msg, from, flen)) != 0 || 138 (r = sshbuf_put_u32(msg, 0)) != 0) 139 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 140 free(blob); 141 send_msg(msg); 142 sshbuf_reset(msg); 143 144 if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) { 145 if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0) 146 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 147 if (slen <= (size_t)RSA_size(rsa)) { 148 memcpy(to, signature, slen); 149 ret = slen; 150 } 151 free(signature); 152 } 153 sshbuf_free(msg); 154 return (ret); 155 } 156 157 /* redirect the private key encrypt operation to the ssh-pkcs11-helper */ 158 static int 159 wrap_key(RSA *rsa) 160 { 161 static RSA_METHOD *helper_rsa; 162 163 if ((helper_rsa = RSA_meth_dup(RSA_get_default_method())) == NULL) 164 fatal("%s: RSA_meth_dup failed", __func__); 165 if (!RSA_meth_set1_name(helper_rsa, "ssh-pkcs11-helper") || 166 !RSA_meth_set_priv_enc(helper_rsa, pkcs11_rsa_private_encrypt)) 167 fatal("%s: failed to prepare method", __func__); 168 RSA_set_method(rsa, helper_rsa); 169 return (0); 170 } 171 172 static int 173 pkcs11_start_helper(void) 174 { 175 int pair[2]; 176 177 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) { 178 error("socketpair: %s", strerror(errno)); 179 return (-1); 180 } 181 if ((pid = fork()) == -1) { 182 error("fork: %s", strerror(errno)); 183 return (-1); 184 } else if (pid == 0) { 185 if ((dup2(pair[1], STDIN_FILENO) == -1) || 186 (dup2(pair[1], STDOUT_FILENO) == -1)) { 187 fprintf(stderr, "dup2: %s\n", strerror(errno)); 188 _exit(1); 189 } 190 close(pair[0]); 191 close(pair[1]); 192 execlp(_PATH_SSH_PKCS11_HELPER, _PATH_SSH_PKCS11_HELPER, 193 (char *)NULL); 194 fprintf(stderr, "exec: %s: %s\n", _PATH_SSH_PKCS11_HELPER, 195 strerror(errno)); 196 _exit(1); 197 } 198 close(pair[1]); 199 fd = pair[0]; 200 return (0); 201 } 202 203 int 204 pkcs11_add_provider(char *name, char *pin, struct sshkey ***keysp) 205 { 206 struct sshkey *k; 207 int r; 208 u_char *blob; 209 size_t blen; 210 u_int nkeys, i; 211 struct sshbuf *msg; 212 213 if (fd < 0 && pkcs11_start_helper() < 0) 214 return (-1); 215 216 if ((msg = sshbuf_new()) == NULL) 217 fatal("%s: sshbuf_new failed", __func__); 218 if ((r = sshbuf_put_u8(msg, SSH_AGENTC_ADD_SMARTCARD_KEY)) != 0 || 219 (r = sshbuf_put_cstring(msg, name)) != 0 || 220 (r = sshbuf_put_cstring(msg, pin)) != 0) 221 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 222 send_msg(msg); 223 sshbuf_reset(msg); 224 225 if (recv_msg(msg) == SSH2_AGENT_IDENTITIES_ANSWER) { 226 if ((r = sshbuf_get_u32(msg, &nkeys)) != 0) 227 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 228 *keysp = xcalloc(nkeys, sizeof(struct sshkey *)); 229 for (i = 0; i < nkeys; i++) { 230 /* XXX clean up properly instead of fatal() */ 231 if ((r = sshbuf_get_string(msg, &blob, &blen)) != 0 || 232 (r = sshbuf_skip_string(msg)) != 0) 233 fatal("%s: buffer error: %s", 234 __func__, ssh_err(r)); 235 if ((r = sshkey_from_blob(blob, blen, &k)) != 0) 236 fatal("%s: bad key: %s", __func__, ssh_err(r)); 237 wrap_key(k->rsa); 238 (*keysp)[i] = k; 239 free(blob); 240 } 241 } else { 242 nkeys = -1; 243 } 244 sshbuf_free(msg); 245 return (nkeys); 246 } 247 248 int 249 pkcs11_del_provider(char *name) 250 { 251 int r, ret = -1; 252 struct sshbuf *msg; 253 254 if ((msg = sshbuf_new()) == NULL) 255 fatal("%s: sshbuf_new failed", __func__); 256 if ((r = sshbuf_put_u8(msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY)) != 0 || 257 (r = sshbuf_put_cstring(msg, name)) != 0 || 258 (r = sshbuf_put_cstring(msg, "")) != 0) 259 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 260 send_msg(msg); 261 sshbuf_reset(msg); 262 263 if (recv_msg(msg) == SSH_AGENT_SUCCESS) 264 ret = 0; 265 sshbuf_free(msg); 266 return (ret); 267 } 268 269 #endif /* ENABLE_PKCS11 */ 270