crypto/openssh/ssh-pkcs11-helper.c

   1 /* $OpenBSD: ssh-pkcs11-helper.c,v 1.13 2017/05/30 08:52:19 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 #include <sys/types.h>
  21 #ifdef HAVE_SYS_TIME_H
  22 # include <sys/time.h>
  23 #endif
  24
  25 #include "openbsd-compat/sys-queue.h"
  26
  27 #include <stdarg.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30 #include <errno.h>
  31
  32 #include "xmalloc.h"
  33 #include "buffer.h"
  34 #include "log.h"
  35 #include "misc.h"
  36 #include "key.h"
  37 #include "authfd.h"
  38 #include "ssh-pkcs11.h"
  39
  40 #ifdef ENABLE_PKCS11
  41
  42 /* borrows code from sftp-server and ssh-agent */
  43
  44 struct pkcs11_keyinfo {
  45         struct sshkey   *key;
  46         char            *providername;
  47         TAILQ_ENTRY(pkcs11_keyinfo) next;
  48 };
  49
  50 TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist;
  51
  52 #define MAX_MSG_LENGTH          10240 /*XXX*/
  53
  54 /* helper */
  55 #define get_int()                       buffer_get_int(&iqueue);
  56 #define get_string(lenp)                buffer_get_string(&iqueue, lenp);
  57
  58 /* input and output queue */
  59 Buffer iqueue;
  60 Buffer oqueue;
  61
  62 static void
  63 add_key(struct sshkey *k, char *name)
  64 {
  65         struct pkcs11_keyinfo *ki;
  66
  67         ki = xcalloc(1, sizeof(*ki));
  68         ki->providername = xstrdup(name);
  69         ki->key = k;
  70         TAILQ_INSERT_TAIL(&pkcs11_keylist, ki, next);
  71 }
  72
  73 static void
  74 del_keys_by_name(char *name)
  75 {
  76         struct pkcs11_keyinfo *ki, *nxt;
  77
  78         for (ki = TAILQ_FIRST(&pkcs11_keylist); ki; ki = nxt) {
  79                 nxt = TAILQ_NEXT(ki, next);
  80                 if (!strcmp(ki->providername, name)) {
  81                         TAILQ_REMOVE(&pkcs11_keylist, ki, next);
  82                         free(ki->providername);
  83                         key_free(ki->key);
  84                         free(ki);
  85                 }
  86         }
  87 }
  88
  89 /* lookup matching 'private' key */
  90 static struct sshkey *
  91 lookup_key(struct sshkey *k)
  92 {
  93         struct pkcs11_keyinfo *ki;
  94
  95         TAILQ_FOREACH(ki, &pkcs11_keylist, next) {
  96                 debug("check %p %s", ki, ki->providername);
  97                 if (key_equal(k, ki->key))
  98                         return (ki->key);
  99         }
 100         return (NULL);
 101 }
 102
 103 static void
 104 send_msg(Buffer *m)
 105 {
 106         int mlen = buffer_len(m);
 107
 108         buffer_put_int(&oqueue, mlen);
 109         buffer_append(&oqueue, buffer_ptr(m), mlen);
 110         buffer_consume(m, mlen);
 111 }
 112
 113 static void
 114 process_add(void)
 115 {
 116         char *name, *pin;
 117         struct sshkey **keys;
 118         int i, nkeys;
 119         u_char *blob;
 120         u_int blen;
 121         Buffer msg;
 122
 123         buffer_init(&msg);
 124         name = get_string(NULL);
 125         pin = get_string(NULL);
 126         if ((nkeys = pkcs11_add_provider(name, pin, &keys)) > 0) {
 127                 buffer_put_char(&msg, SSH2_AGENT_IDENTITIES_ANSWER);
 128                 buffer_put_int(&msg, nkeys);
 129                 for (i = 0; i < nkeys; i++) {
 130                         if (key_to_blob(keys[i], &blob, &blen) == 0)
 131                                 continue;
 132                         buffer_put_string(&msg, blob, blen);
 133                         buffer_put_cstring(&msg, name);
 134                         free(blob);
 135                         add_key(keys[i], name);
 136                 }
 137                 free(keys);
 138         } else {
 139                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 140         }
 141         free(pin);
 142         free(name);
 143         send_msg(&msg);
 144         buffer_free(&msg);
 145 }
 146
 147 static void
 148 process_del(void)
 149 {
 150         char *name, *pin;
 151         Buffer msg;
 152
 153         buffer_init(&msg);
 154         name = get_string(NULL);
 155         pin = get_string(NULL);
 156         del_keys_by_name(name);
 157         if (pkcs11_del_provider(name) == 0)
 158                  buffer_put_char(&msg, SSH_AGENT_SUCCESS);
 159         else
 160                  buffer_put_char(&msg, SSH_AGENT_FAILURE);
 161         free(pin);
 162         free(name);
 163         send_msg(&msg);
 164         buffer_free(&msg);
 165 }
 166
 167 static void
 168 process_sign(void)
 169 {
 170         u_char *blob, *data, *signature = NULL;
 171         u_int blen, dlen, slen = 0;
 172         int ok = -1;
 173         struct sshkey *key, *found;
 174         Buffer msg;
 175
 176         blob = get_string(&blen);
 177         data = get_string(&dlen);
 178         (void)get_int(); /* XXX ignore flags */
 179
 180         if ((key = key_from_blob(blob, blen)) != NULL) {
 181                 if ((found = lookup_key(key)) != NULL) {
 182 #ifdef WITH_OPENSSL
 183                         int ret;
 184
 185                         slen = RSA_size(key->rsa);
 186                         signature = xmalloc(slen);
 187                         if ((ret = RSA_private_encrypt(dlen, data, signature,
 188                             found->rsa, RSA_PKCS1_PADDING)) != -1) {
 189                                 slen = ret;
 190                                 ok = 0;
 191                         }
 192 #endif /* WITH_OPENSSL */
 193                 }
 194                 key_free(key);
 195         }
 196         buffer_init(&msg);
 197         if (ok == 0) {
 198                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 199                 buffer_put_string(&msg, signature, slen);
 200         } else {
 201                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 202         }
 203         free(data);
 204         free(blob);
 205         free(signature);
 206         send_msg(&msg);
 207         buffer_free(&msg);
 208 }
 209
 210 static void
 211 process(void)
 212 {
 213         u_int msg_len;
 214         u_int buf_len;
 215         u_int consumed;
 216         u_int type;
 217         u_char *cp;
 218
 219         buf_len = buffer_len(&iqueue);
 220         if (buf_len < 5)
 221                 return;         /* Incomplete message. */
 222         cp = buffer_ptr(&iqueue);
 223         msg_len = get_u32(cp);
 224         if (msg_len > MAX_MSG_LENGTH) {
 225                 error("bad message len %d", msg_len);
 226                 cleanup_exit(11);
 227         }
 228         if (buf_len < msg_len + 4)
 229                 return;
 230         buffer_consume(&iqueue, 4);
 231         buf_len -= 4;
 232         type = buffer_get_char(&iqueue);
 233         switch (type) {
 234         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 235                 debug("process_add");
 236                 process_add();
 237                 break;
 238         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 239                 debug("process_del");
 240                 process_del();
 241                 break;
 242         case SSH2_AGENTC_SIGN_REQUEST:
 243                 debug("process_sign");
 244                 process_sign();
 245                 break;
 246         default:
 247                 error("Unknown message %d", type);
 248                 break;
 249         }
 250         /* discard the remaining bytes from the current packet */
 251         if (buf_len < buffer_len(&iqueue)) {
 252                 error("iqueue grew unexpectedly");
 253                 cleanup_exit(255);
 254         }
 255         consumed = buf_len - buffer_len(&iqueue);
 256         if (msg_len < consumed) {
 257                 error("msg_len %d < consumed %d", msg_len, consumed);
 258                 cleanup_exit(255);
 259         }
 260         if (msg_len > consumed)
 261                 buffer_consume(&iqueue, msg_len - consumed);
 262 }
 263
 264 void
 265 cleanup_exit(int i)
 266 {
 267         /* XXX */
 268         _exit(i);
 269 }
 270
 271 int
 272 main(int argc, char **argv)
 273 {
 274         fd_set *rset, *wset;
 275         int in, out, max, log_stderr = 0;
 276         ssize_t len, olen, set_size;
 277         SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
 278         LogLevel log_level = SYSLOG_LEVEL_ERROR;
 279         char buf[4*4096];
 280
 281         extern char *__progname;
 282
 283         ssh_malloc_init();      /* must be called before any mallocs */
 284         TAILQ_INIT(&pkcs11_keylist);
 285         pkcs11_init(0);
 286
 287         seed_rng();
 288         __progname = ssh_get_progname(argv[0]);
 289
 290         log_init(__progname, log_level, log_facility, log_stderr);
 291
 292         in = STDIN_FILENO;
 293         out = STDOUT_FILENO;
 294
 295         max = 0;
 296         if (in > max)
 297                 max = in;
 298         if (out > max)
 299                 max = out;
 300
 301         buffer_init(&iqueue);
 302         buffer_init(&oqueue);
 303
 304         set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
 305         rset = xmalloc(set_size);
 306         wset = xmalloc(set_size);
 307
 308         for (;;) {
 309                 memset(rset, 0, set_size);
 310                 memset(wset, 0, set_size);
 311
 312                 /*
 313                  * Ensure that we can read a full buffer and handle
 314                  * the worst-case length packet it can generate,
 315                  * otherwise apply backpressure by stopping reads.
 316                  */
 317                 if (buffer_check_alloc(&iqueue, sizeof(buf)) &&
 318                     buffer_check_alloc(&oqueue, MAX_MSG_LENGTH))
 319                         FD_SET(in, rset);
 320
 321                 olen = buffer_len(&oqueue);
 322                 if (olen > 0)
 323                         FD_SET(out, wset);
 324
 325                 if (select(max+1, rset, wset, NULL, NULL) < 0) {
 326                         if (errno == EINTR)
 327                                 continue;
 328                         error("select: %s", strerror(errno));
 329                         cleanup_exit(2);
 330                 }
 331
 332                 /* copy stdin to iqueue */
 333                 if (FD_ISSET(in, rset)) {
 334                         len = read(in, buf, sizeof buf);
 335                         if (len == 0) {
 336                                 debug("read eof");
 337                                 cleanup_exit(0);
 338                         } else if (len < 0) {
 339                                 error("read: %s", strerror(errno));
 340                                 cleanup_exit(1);
 341                         } else {
 342                                 buffer_append(&iqueue, buf, len);
 343                         }
 344                 }
 345                 /* send oqueue to stdout */
 346                 if (FD_ISSET(out, wset)) {
 347                         len = write(out, buffer_ptr(&oqueue), olen);
 348                         if (len < 0) {
 349                                 error("write: %s", strerror(errno));
 350                                 cleanup_exit(1);
 351                         } else {
 352                                 buffer_consume(&oqueue, len);
 353                         }
 354                 }
 355
 356                 /*
 357                  * Process requests from client if we can fit the results
 358                  * into the output buffer, otherwise stop processing input
 359                  * and let the output queue drain.
 360                  */
 361                 if (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH))
 362                         process();
 363         }
 364 }
 365 #else /* ENABLE_PKCS11 */
 366 int
 367 main(int argc, char **argv)
 368 {
 369         extern char *__progname;
 370
 371         __progname = ssh_get_progname(argv[0]);
 372         log_init(__progname, SYSLOG_LEVEL_ERROR, SYSLOG_FACILITY_AUTH, 0);
 373         fatal("PKCS#11 support disabled at compile time");
 374 }
 375 #endif /* ENABLE_PKCS11 */