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 <sys/types.h> 19 #include <sys/time.h> 20 #include <sys/socket.h> 21 22 #include <stdarg.h> 23 #include <string.h> 24 #include <unistd.h> 25 #include <errno.h> 26 27 #include "pathnames.h" 28 #include "xmalloc.h" 29 #include "buffer.h" 30 #include "log.h" 31 #include "misc.h" 32 #include "key.h" 33 #include "authfd.h" 34 #include "atomicio.h" 35 #include "ssh-pkcs11.h" 36 37 /* borrows code from sftp-server and ssh-agent */ 38 39 int fd = -1; 40 pid_t pid = -1; 41 42 static void 43 send_msg(Buffer *m) 44 { 45 u_char buf[4]; 46 int mlen = buffer_len(m); 47 48 put_u32(buf, mlen); 49 if (atomicio(vwrite, fd, buf, 4) != 4 || 50 atomicio(vwrite, fd, buffer_ptr(m), 51 buffer_len(m)) != buffer_len(m)) 52 error("write to helper failed"); 53 buffer_consume(m, mlen); 54 } 55 56 static int 57 recv_msg(Buffer *m) 58 { 59 u_int l, len; 60 u_char buf[1024]; 61 62 if ((len = atomicio(read, fd, buf, 4)) != 4) { 63 error("read from helper failed: %u", len); 64 return (0); /* XXX */ 65 } 66 len = get_u32(buf); 67 if (len > 256 * 1024) 68 fatal("response too long: %u", len); 69 /* read len bytes into m */ 70 buffer_clear(m); 71 while (len > 0) { 72 l = len; 73 if (l > sizeof(buf)) 74 l = sizeof(buf); 75 if (atomicio(read, fd, buf, l) != l) { 76 error("response from helper failed."); 77 return (0); /* XXX */ 78 } 79 buffer_append(m, buf, l); 80 len -= l; 81 } 82 return (buffer_get_char(m)); 83 } 84 85 int 86 pkcs11_init(int interactive) 87 { 88 return (0); 89 } 90 91 void 92 pkcs11_terminate(void) 93 { 94 close(fd); 95 } 96 97 static int 98 pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa, 99 int padding) 100 { 101 Key key; 102 u_char *blob, *signature = NULL; 103 u_int blen, slen = 0; 104 int ret = -1; 105 Buffer msg; 106 107 if (padding != RSA_PKCS1_PADDING) 108 return (-1); 109 key.type = KEY_RSA; 110 key.rsa = rsa; 111 if (key_to_blob(&key, &blob, &blen) == 0) 112 return -1; 113 buffer_init(&msg); 114 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST); 115 buffer_put_string(&msg, blob, blen); 116 buffer_put_string(&msg, from, flen); 117 buffer_put_int(&msg, 0); 118 xfree(blob); 119 send_msg(&msg); 120 121 if (recv_msg(&msg) == SSH2_AGENT_SIGN_RESPONSE) { 122 signature = buffer_get_string(&msg, &slen); 123 if (slen <= (u_int)RSA_size(rsa)) { 124 memcpy(to, signature, slen); 125 ret = slen; 126 } 127 xfree(signature); 128 } 129 return (ret); 130 } 131 132 /* redirect the private key encrypt operation to the ssh-pkcs11-helper */ 133 static int 134 wrap_key(RSA *rsa) 135 { 136 static RSA_METHOD helper_rsa; 137 138 memcpy(&helper_rsa, RSA_get_default_method(), sizeof(helper_rsa)); 139 helper_rsa.name = "ssh-pkcs11-helper"; 140 helper_rsa.rsa_priv_enc = pkcs11_rsa_private_encrypt; 141 RSA_set_method(rsa, &helper_rsa); 142 return (0); 143 } 144 145 static int 146 pkcs11_start_helper(void) 147 { 148 int pair[2]; 149 150 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) { 151 error("socketpair: %s", strerror(errno)); 152 return (-1); 153 } 154 if ((pid = fork()) == -1) { 155 error("fork: %s", strerror(errno)); 156 return (-1); 157 } else if (pid == 0) { 158 if ((dup2(pair[1], STDIN_FILENO) == -1) || 159 (dup2(pair[1], STDOUT_FILENO) == -1)) { 160 fprintf(stderr, "dup2: %s\n", strerror(errno)); 161 _exit(1); 162 } 163 close(pair[0]); 164 close(pair[1]); 165 execlp(_PATH_SSH_PKCS11_HELPER, _PATH_SSH_PKCS11_HELPER, 166 (char *) 0); 167 fprintf(stderr, "exec: %s: %s\n", _PATH_SSH_PKCS11_HELPER, 168 strerror(errno)); 169 _exit(1); 170 } 171 close(pair[1]); 172 fd = pair[0]; 173 return (0); 174 } 175 176 int 177 pkcs11_add_provider(char *name, char *pin, Key ***keysp) 178 { 179 Key *k; 180 int i, nkeys; 181 u_char *blob; 182 u_int blen; 183 Buffer msg; 184 185 if (fd < 0 && pkcs11_start_helper() < 0) 186 return (-1); 187 188 buffer_init(&msg); 189 buffer_put_char(&msg, SSH_AGENTC_ADD_SMARTCARD_KEY); 190 buffer_put_cstring(&msg, name); 191 buffer_put_cstring(&msg, pin); 192 send_msg(&msg); 193 buffer_clear(&msg); 194 195 if (recv_msg(&msg) == SSH2_AGENT_IDENTITIES_ANSWER) { 196 nkeys = buffer_get_int(&msg); 197 *keysp = xcalloc(nkeys, sizeof(Key *)); 198 for (i = 0; i < nkeys; i++) { 199 blob = buffer_get_string(&msg, &blen); 200 xfree(buffer_get_string(&msg, NULL)); 201 k = key_from_blob(blob, blen); 202 wrap_key(k->rsa); 203 (*keysp)[i] = k; 204 xfree(blob); 205 } 206 } else { 207 nkeys = -1; 208 } 209 buffer_free(&msg); 210 return (nkeys); 211 } 212 213 int 214 pkcs11_del_provider(char *name) 215 { 216 int ret = -1; 217 Buffer msg; 218 219 buffer_init(&msg); 220 buffer_put_char(&msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY); 221 buffer_put_cstring(&msg, name); 222 buffer_put_cstring(&msg, ""); 223 send_msg(&msg); 224 buffer_clear(&msg); 225 226 if (recv_msg(&msg) == SSH_AGENT_SUCCESS) 227 ret = 0; 228 buffer_free(&msg); 229 return (ret); 230 } 231