crypto/openssh/ssh-pkcs11-client.c

   1 /* $OpenBSD: ssh-pkcs11-client.c,v 1.7 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 #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 "buffer.h"
  38 #include "log.h"
  39 #include "misc.h"
  40 #include "key.h"
  41 #include "authfd.h"
  42 #include "atomicio.h"
  43 #include "ssh-pkcs11.h"
  44
  45 /* borrows code from sftp-server and ssh-agent */
  46
  47 int fd = -1;
  48 pid_t pid = -1;
  49
  50 static void
  51 send_msg(Buffer *m)
  52 {
  53         u_char buf[4];
  54         int mlen = buffer_len(m);
  55
  56         put_u32(buf, mlen);
  57         if (atomicio(vwrite, fd, buf, 4) != 4 ||
  58             atomicio(vwrite, fd, buffer_ptr(m),
  59             buffer_len(m)) != buffer_len(m))
  60                 error("write to helper failed");
  61         buffer_consume(m, mlen);
  62 }
  63
  64 static int
  65 recv_msg(Buffer *m)
  66 {
  67         u_int l, len;
  68         u_char buf[1024];
  69
  70         if ((len = atomicio(read, fd, buf, 4)) != 4) {
  71                 error("read from helper failed: %u", len);
  72                 return (0); /* XXX */
  73         }
  74         len = get_u32(buf);
  75         if (len > 256 * 1024)
  76                 fatal("response too long: %u", len);
  77         /* read len bytes into m */
  78         buffer_clear(m);
  79         while (len > 0) {
  80                 l = len;
  81                 if (l > sizeof(buf))
  82                         l = sizeof(buf);
  83                 if (atomicio(read, fd, buf, l) != l) {
  84                         error("response from helper failed.");
  85                         return (0); /* XXX */
  86                 }
  87                 buffer_append(m, buf, l);
  88                 len -= l;
  89         }
  90         return (buffer_get_char(m));
  91 }
  92
  93 int
  94 pkcs11_init(int interactive)
  95 {
  96         return (0);
  97 }
  98
  99 void
 100 pkcs11_terminate(void)
 101 {
 102         close(fd);
 103 }
 104
 105 static int
 106 pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
 107     int padding)
 108 {
 109         struct sshkey key;      /* XXX */
 110         u_char *blob, *signature = NULL;
 111         u_int blen, slen = 0;
 112         int ret = -1;
 113         Buffer msg;
 114
 115         if (padding != RSA_PKCS1_PADDING)
 116                 return (-1);
 117         key.type = KEY_RSA;
 118         key.rsa = rsa;
 119         if (key_to_blob(&key, &blob, &blen) == 0)
 120                 return -1;
 121         buffer_init(&msg);
 122         buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
 123         buffer_put_string(&msg, blob, blen);
 124         buffer_put_string(&msg, from, flen);
 125         buffer_put_int(&msg, 0);
 126         free(blob);
 127         send_msg(&msg);
 128         buffer_clear(&msg);
 129
 130         if (recv_msg(&msg) == SSH2_AGENT_SIGN_RESPONSE) {
 131                 signature = buffer_get_string(&msg, &slen);
 132                 if (slen <= (u_int)RSA_size(rsa)) {
 133                         memcpy(to, signature, slen);
 134                         ret = slen;
 135                 }
 136                 free(signature);
 137         }
 138         buffer_free(&msg);
 139         return (ret);
 140 }
 141
 142 /* redirect the private key encrypt operation to the ssh-pkcs11-helper */
 143 static int
 144 wrap_key(RSA *rsa)
 145 {
 146         static RSA_METHOD helper_rsa;
 147
 148         memcpy(&helper_rsa, RSA_get_default_method(), sizeof(helper_rsa));
 149         helper_rsa.name = "ssh-pkcs11-helper";
 150         helper_rsa.rsa_priv_enc = pkcs11_rsa_private_encrypt;
 151         RSA_set_method(rsa, &helper_rsa);
 152         return (0);
 153 }
 154
 155 static int
 156 pkcs11_start_helper(void)
 157 {
 158         int pair[2];
 159
 160         if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
 161                 error("socketpair: %s", strerror(errno));
 162                 return (-1);
 163         }
 164         if ((pid = fork()) == -1) {
 165                 error("fork: %s", strerror(errno));
 166                 return (-1);
 167         } else if (pid == 0) {
 168                 if ((dup2(pair[1], STDIN_FILENO) == -1) ||
 169                     (dup2(pair[1], STDOUT_FILENO) == -1)) {
 170                         fprintf(stderr, "dup2: %s\n", strerror(errno));
 171                         _exit(1);
 172                 }
 173                 close(pair[0]);
 174                 close(pair[1]);
 175                 execlp(_PATH_SSH_PKCS11_HELPER, _PATH_SSH_PKCS11_HELPER,
 176                     (char *)NULL);
 177                 fprintf(stderr, "exec: %s: %s\n", _PATH_SSH_PKCS11_HELPER,
 178                     strerror(errno));
 179                 _exit(1);
 180         }
 181         close(pair[1]);
 182         fd = pair[0];
 183         return (0);
 184 }
 185
 186 int
 187 pkcs11_add_provider(char *name, char *pin, Key ***keysp)
 188 {
 189         struct sshkey *k;
 190         int i, nkeys;
 191         u_char *blob;
 192         u_int blen;
 193         Buffer msg;
 194
 195         if (fd < 0 && pkcs11_start_helper() < 0)
 196                 return (-1);
 197
 198         buffer_init(&msg);
 199         buffer_put_char(&msg, SSH_AGENTC_ADD_SMARTCARD_KEY);
 200         buffer_put_cstring(&msg, name);
 201         buffer_put_cstring(&msg, pin);
 202         send_msg(&msg);
 203         buffer_clear(&msg);
 204
 205         if (recv_msg(&msg) == SSH2_AGENT_IDENTITIES_ANSWER) {
 206                 nkeys = buffer_get_int(&msg);
 207                 *keysp = xcalloc(nkeys, sizeof(Key *));
 208                 for (i = 0; i < nkeys; i++) {
 209                         blob = buffer_get_string(&msg, &blen);
 210                         free(buffer_get_string(&msg, NULL));
 211                         k = key_from_blob(blob, blen);
 212                         wrap_key(k->rsa);
 213                         (*keysp)[i] = k;
 214                         free(blob);
 215                 }
 216         } else {
 217                 nkeys = -1;
 218         }
 219         buffer_free(&msg);
 220         return (nkeys);
 221 }
 222
 223 int
 224 pkcs11_del_provider(char *name)
 225 {
 226         int ret = -1;
 227         Buffer msg;
 228
 229         buffer_init(&msg);
 230         buffer_put_char(&msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY);
 231         buffer_put_cstring(&msg, name);
 232         buffer_put_cstring(&msg, "");
 233         send_msg(&msg);
 234         buffer_clear(&msg);
 235
 236         if (recv_msg(&msg) == SSH_AGENT_SUCCESS)
 237                 ret = 0;
 238         buffer_free(&msg);
 239         return (ret);
 240 }
 241
 242 #endif /* ENABLE_PKCS11 */