1 /* $OpenBSD: ssh-pkcs11-client.c,v 1.8 2018/02/05 05:37:46 tb 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 <openssl/rsa.h> 28 29 #include "pathnames.h" 30 #include "xmalloc.h" 31 #include "buffer.h" 32 #include "log.h" 33 #include "misc.h" 34 #include "key.h" 35 #include "authfd.h" 36 #include "atomicio.h" 37 #include "ssh-pkcs11.h" 38 39 /* borrows code from sftp-server and ssh-agent */ 40 41 int fd = -1; 42 pid_t pid = -1; 43 44 static void 45 send_msg(Buffer *m) 46 { 47 u_char buf[4]; 48 int mlen = buffer_len(m); 49 50 put_u32(buf, mlen); 51 if (atomicio(vwrite, fd, buf, 4) != 4 || 52 atomicio(vwrite, fd, buffer_ptr(m), 53 buffer_len(m)) != buffer_len(m)) 54 error("write to helper failed"); 55 buffer_consume(m, mlen); 56 } 57 58 static int 59 recv_msg(Buffer *m) 60 { 61 u_int l, len; 62 u_char buf[1024]; 63 64 if ((len = atomicio(read, fd, buf, 4)) != 4) { 65 error("read from helper failed: %u", len); 66 return (0); /* XXX */ 67 } 68 len = get_u32(buf); 69 if (len > 256 * 1024) 70 fatal("response too long: %u", len); 71 /* read len bytes into m */ 72 buffer_clear(m); 73 while (len > 0) { 74 l = len; 75 if (l > sizeof(buf)) 76 l = sizeof(buf); 77 if (atomicio(read, fd, buf, l) != l) { 78 error("response from helper failed."); 79 return (0); /* XXX */ 80 } 81 buffer_append(m, buf, l); 82 len -= l; 83 } 84 return (buffer_get_char(m)); 85 } 86 87 int 88 pkcs11_init(int interactive) 89 { 90 return (0); 91 } 92 93 void 94 pkcs11_terminate(void) 95 { 96 if (fd >= 0) 97 close(fd); 98 } 99 100 static int 101 pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa, 102 int padding) 103 { 104 struct sshkey key; /* XXX */ 105 u_char *blob, *signature = NULL; 106 u_int blen, slen = 0; 107 int ret = -1; 108 Buffer msg; 109 110 if (padding != RSA_PKCS1_PADDING) 111 return (-1); 112 key.type = KEY_RSA; 113 key.rsa = rsa; 114 if (key_to_blob(&key, &blob, &blen) == 0) 115 return -1; 116 buffer_init(&msg); 117 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST); 118 buffer_put_string(&msg, blob, blen); 119 buffer_put_string(&msg, from, flen); 120 buffer_put_int(&msg, 0); 121 free(blob); 122 send_msg(&msg); 123 buffer_clear(&msg); 124 125 if (recv_msg(&msg) == SSH2_AGENT_SIGN_RESPONSE) { 126 signature = buffer_get_string(&msg, &slen); 127 if (slen <= (u_int)RSA_size(rsa)) { 128 memcpy(to, signature, slen); 129 ret = slen; 130 } 131 free(signature); 132 } 133 buffer_free(&msg); 134 return (ret); 135 } 136 137 /* redirect the private key encrypt operation to the ssh-pkcs11-helper */ 138 static int 139 wrap_key(RSA *rsa) 140 { 141 static RSA_METHOD helper_rsa; 142 143 memcpy(&helper_rsa, RSA_get_default_method(), sizeof(helper_rsa)); 144 helper_rsa.name = "ssh-pkcs11-helper"; 145 helper_rsa.rsa_priv_enc = pkcs11_rsa_private_encrypt; 146 RSA_set_method(rsa, &helper_rsa); 147 return (0); 148 } 149 150 static int 151 pkcs11_start_helper(void) 152 { 153 int pair[2]; 154 155 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) { 156 error("socketpair: %s", strerror(errno)); 157 return (-1); 158 } 159 if ((pid = fork()) == -1) { 160 error("fork: %s", strerror(errno)); 161 return (-1); 162 } else if (pid == 0) { 163 if ((dup2(pair[1], STDIN_FILENO) == -1) || 164 (dup2(pair[1], STDOUT_FILENO) == -1)) { 165 fprintf(stderr, "dup2: %s\n", strerror(errno)); 166 _exit(1); 167 } 168 close(pair[0]); 169 close(pair[1]); 170 execlp(_PATH_SSH_PKCS11_HELPER, _PATH_SSH_PKCS11_HELPER, 171 (char *)NULL); 172 fprintf(stderr, "exec: %s: %s\n", _PATH_SSH_PKCS11_HELPER, 173 strerror(errno)); 174 _exit(1); 175 } 176 close(pair[1]); 177 fd = pair[0]; 178 return (0); 179 } 180 181 int 182 pkcs11_add_provider(char *name, char *pin, Key ***keysp) 183 { 184 struct sshkey *k; 185 int i, nkeys; 186 u_char *blob; 187 u_int blen; 188 Buffer msg; 189 190 if (fd < 0 && pkcs11_start_helper() < 0) 191 return (-1); 192 193 buffer_init(&msg); 194 buffer_put_char(&msg, SSH_AGENTC_ADD_SMARTCARD_KEY); 195 buffer_put_cstring(&msg, name); 196 buffer_put_cstring(&msg, pin); 197 send_msg(&msg); 198 buffer_clear(&msg); 199 200 if (recv_msg(&msg) == SSH2_AGENT_IDENTITIES_ANSWER) { 201 nkeys = buffer_get_int(&msg); 202 *keysp = xcalloc(nkeys, sizeof(Key *)); 203 for (i = 0; i < nkeys; i++) { 204 blob = buffer_get_string(&msg, &blen); 205 free(buffer_get_string(&msg, NULL)); 206 k = key_from_blob(blob, blen); 207 wrap_key(k->rsa); 208 (*keysp)[i] = k; 209 free(blob); 210 } 211 } else { 212 nkeys = -1; 213 } 214 buffer_free(&msg); 215 return (nkeys); 216 } 217 218 int 219 pkcs11_del_provider(char *name) 220 { 221 int ret = -1; 222 Buffer msg; 223 224 buffer_init(&msg); 225 buffer_put_char(&msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY); 226 buffer_put_cstring(&msg, name); 227 buffer_put_cstring(&msg, ""); 228 send_msg(&msg); 229 buffer_clear(&msg); 230 231 if (recv_msg(&msg) == SSH_AGENT_SUCCESS) 232 ret = 0; 233 buffer_free(&msg); 234 return (ret); 235 } 236