eng_keystore.cpp revision 98c2f8fcc1263a9d94adac66994fffc96c0df699
1/* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 16 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY 17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 20 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 * 24 */ 25 26#include <keystore.h> 27 28#include <utils/UniquePtr.h> 29 30#include <sys/socket.h> 31#include <stdarg.h> 32#include <string.h> 33 34#include <openssl/objects.h> 35#include <openssl/engine.h> 36#include <openssl/evp.h> 37 38#define LOG_NDEBUG 0 39#define LOG_TAG "OpenSSL-keystore" 40#include <cutils/log.h> 41 42#include <keystore_client.h> 43 44 45#define DYNAMIC_ENGINE 46#define KEYSTORE_ENGINE_ID "keystore" 47#define KEYSTORE_ENGINE_NAME "Android keystore engine" 48 49/** 50 * Many OpenSSL APIs take ownership of an argument on success but don't free the argument 51 * on failure. This means we need to tell our scoped pointers when we've transferred ownership, 52 * without triggering a warning by not using the result of release(). 53 */ 54#define OWNERSHIP_TRANSFERRED(obj) \ 55 typeof (obj.release()) _dummy __attribute__((unused)) = obj.release() 56 57struct ENGINE_Delete { 58 void operator()(ENGINE* p) const { 59 ENGINE_free(p); 60 } 61}; 62typedef UniquePtr<ENGINE, ENGINE_Delete> Unique_ENGINE; 63 64struct EVP_PKEY_Delete { 65 void operator()(EVP_PKEY* p) const { 66 EVP_PKEY_free(p); 67 } 68}; 69typedef UniquePtr<EVP_PKEY, EVP_PKEY_Delete> Unique_EVP_PKEY; 70 71struct RSA_Delete { 72 void operator()(RSA* p) const { 73 RSA_free(p); 74 } 75}; 76typedef UniquePtr<RSA, RSA_Delete> Unique_RSA; 77 78 79/* 80 * RSA ex_data index for keystore's key handle. 81 */ 82static int rsa_key_handle; 83 84 85/** 86 * Execute a keystore command. The number of arguments should be passed in 87 * "numArgs" and be preceeded by the length as a size_t. 88 * 89 * If a reply is expected, the "reply" field must be of size 90 * KEYSTORE_MESSAGE_SIZE. 91 * 92 * Example for numArgs == 2: 93 * keystore_cmd(cmd, reply, 2, size_t, char*, size_t, char*); 94 * 95 * The return value will be the length of the reply stored in "reply." 96 * If an error occurs, the return value will be -1. 97 */ 98 99/** 100 * Makes sure the ex_data for the keyhandle is initially set to NULL. 101 */ 102int keyhandle_new(void*, void*, CRYPTO_EX_DATA* ad, int idx, long, void*) { 103 return CRYPTO_set_ex_data(ad, idx, NULL); 104} 105 106/** 107 * Frees a previously allocated keyhandle stored in ex_data. 108 */ 109void keyhandle_free(void *, void *ptr, CRYPTO_EX_DATA*, int, long, void*) { 110 char* keyhandle = reinterpret_cast<char*>(ptr); 111 if (keyhandle != NULL) { 112 free(keyhandle); 113 } 114} 115 116/** 117 * Duplicates a keyhandle stored in ex_data in case we copy a key. 118 */ 119int keyhandle_dup(CRYPTO_EX_DATA* to, CRYPTO_EX_DATA*, void *ptrRef, int idx, long, void *) { 120 // This appears to be a bug in OpenSSL. 121 void** ptr = reinterpret_cast<void**>(ptrRef); 122 char* keyhandle = reinterpret_cast<char*>(*ptr); 123 if (keyhandle != NULL) { 124 char* keyhandle_copy = strdup(keyhandle); 125 *ptr = keyhandle_copy; 126 127 // Call this in case OpenSSL is fixed in the future. 128 (void) CRYPTO_set_ex_data(to, idx, keyhandle_copy); 129 } 130 return 1; 131} 132 133int keystore_rsa_priv_enc(int flen, const unsigned char* from, unsigned char* to, RSA* rsa, 134 int padding) { 135 ALOGV("keystore_rsa_sign(%d, %p, %p, %p, %d)", flen, from, to, rsa, padding); 136 137 int num = RSA_size(rsa); 138 UniquePtr<uint8_t> padded(new uint8_t[num]); 139 if (padded.get() == NULL) { 140 ALOGE("could not allocate padded signature"); 141 return 0; 142 } 143 144 switch (padding) { 145 case RSA_PKCS1_PADDING: 146 if (!RSA_padding_add_PKCS1_type_1(padded.get(), num, from, flen)) { 147 return 0; 148 } 149 break; 150 case RSA_X931_PADDING: 151 if (!RSA_padding_add_X931(padded.get(), num, from, flen)) { 152 return 0; 153 } 154 break; 155 case RSA_NO_PADDING: 156 if (!RSA_padding_add_none(padded.get(), num, from, flen)) { 157 return 0; 158 } 159 break; 160 default: 161 ALOGE("Unknown padding type: %d", padding); 162 return 0; 163 } 164 165 uint8_t* key_id = reinterpret_cast<uint8_t*>(RSA_get_ex_data(rsa, rsa_key_handle)); 166 if (key_id == NULL) { 167 ALOGE("key had no key_id!"); 168 return 0; 169 } 170 171 Keystore_Reply reply; 172 if (keystore_cmd(CommandCodes[SIGN], &reply, 2, strlen(reinterpret_cast<const char*>(key_id)), 173 key_id, static_cast<size_t>(num), reinterpret_cast<const uint8_t*>(padded.get())) 174 != NO_ERROR) { 175 ALOGE("There was an error during rsa_mod_exp"); 176 return 0; 177 } 178 179 const size_t replyLen = reply.length(); 180 if (replyLen <= 0) { 181 ALOGW("No valid signature returned"); 182 return 0; 183 } 184 185 memcpy(to, reply.get(), replyLen); 186 187 ALOGV("rsa=%p keystore_rsa_sign => returning %p len %llu", rsa, to, 188 (unsigned long long) replyLen); 189 return static_cast<int>(replyLen); 190} 191 192static RSA_METHOD keystore_rsa_meth = { 193 KEYSTORE_ENGINE_NAME, 194 NULL, /* rsa_pub_enc */ 195 NULL, /* rsa_pub_dec (verification) */ 196 keystore_rsa_priv_enc, /* rsa_priv_enc (signing) */ 197 NULL, /* rsa_priv_dec */ 198 NULL, /* rsa_mod_exp */ 199 NULL, /* bn_mod_exp */ 200 NULL, /* init */ 201 NULL, /* finish */ 202 RSA_FLAG_EXT_PKEY | RSA_FLAG_NO_BLINDING, /* flags */ 203 NULL, /* app_data */ 204 NULL, /* rsa_sign */ 205 NULL, /* rsa_verify */ 206 NULL, /* rsa_keygen */ 207}; 208 209static int register_rsa_methods() { 210 const RSA_METHOD* rsa_meth = RSA_PKCS1_SSLeay(); 211 212 keystore_rsa_meth.rsa_pub_enc = rsa_meth->rsa_pub_enc; 213 keystore_rsa_meth.rsa_pub_dec = rsa_meth->rsa_pub_dec; 214 keystore_rsa_meth.rsa_priv_dec = rsa_meth->rsa_priv_dec; 215 keystore_rsa_meth.rsa_mod_exp = rsa_meth->rsa_mod_exp; 216 keystore_rsa_meth.bn_mod_exp = rsa_meth->bn_mod_exp; 217 218 return 1; 219} 220 221static EVP_PKEY* keystore_loadkey(ENGINE* e, const char* key_id, UI_METHOD *ui_method, 222 void *callback_data) { 223 ALOGV("keystore_loadkey(%p, \"%s\", %p, %p)", e, key_id, ui_method, callback_data); 224 225 Keystore_Reply reply; 226 if (keystore_cmd(CommandCodes[GET_PUBKEY], &reply, 1, strlen(key_id), key_id) != NO_ERROR) { 227 ALOGV("Cannot get public key for %s", key_id); 228 return NULL; 229 } 230 231 const unsigned char* tmp = reinterpret_cast<const unsigned char*>(reply.get()); 232 Unique_EVP_PKEY pkey(d2i_PUBKEY(NULL, &tmp, reply.length())); 233 if (pkey.get() == NULL) { 234 ALOGW("Cannot convert pubkey"); 235 return NULL; 236 } 237 238 switch (EVP_PKEY_type(pkey->type)) { 239 case EVP_PKEY_RSA: { 240 Unique_RSA rsa(EVP_PKEY_get1_RSA(pkey.get())); 241 if (!RSA_set_ex_data(rsa.get(), rsa_key_handle, reinterpret_cast<void*>(strdup(key_id)))) { 242 ALOGW("Could not set ex_data for loaded RSA key"); 243 return NULL; 244 } 245 246 RSA_set_method(rsa.get(), &keystore_rsa_meth); 247 RSA_blinding_off(rsa.get()); 248 249 /* 250 * This should probably be an OpenSSL API, but EVP_PKEY_free calls 251 * ENGINE_finish(), so we need to call ENGINE_init() here. 252 */ 253 ENGINE_init(e); 254 rsa->engine = e; 255 rsa->flags |= RSA_FLAG_EXT_PKEY; 256 257 break; 258 } 259 default: 260 ALOGE("Unsupported key type %d", EVP_PKEY_type(pkey->type)); 261 return NULL; 262 } 263 264 return pkey.release(); 265} 266 267static const ENGINE_CMD_DEFN keystore_cmd_defns[] = { 268 {0, NULL, NULL, 0} 269}; 270 271static int keystore_engine_setup(ENGINE* e) { 272 ALOGV("keystore_engine_setup"); 273 274 if (!ENGINE_set_id(e, KEYSTORE_ENGINE_ID) 275 || !ENGINE_set_name(e, KEYSTORE_ENGINE_NAME) 276 || !ENGINE_set_load_privkey_function(e, keystore_loadkey) 277 || !ENGINE_set_load_pubkey_function(e, keystore_loadkey) 278 || !ENGINE_set_cmd_defns(e, keystore_cmd_defns)) { 279 ALOGE("Could not set up keystore engine"); 280 return 0; 281 } 282 283 if (!ENGINE_set_RSA(e, &keystore_rsa_meth) 284 || !register_rsa_methods()) { 285 ALOGE("Could not set up keystore RSA methods"); 286 return 0; 287 } 288 289 /* We need a handle in the RSA keys as well for keygen. */ 290 rsa_key_handle = RSA_get_ex_new_index(0, NULL, keyhandle_new, keyhandle_dup, keyhandle_free); 291 if (rsa_key_handle < 0) { 292 ALOGE("Could not set up RSA ex_data index"); 293 return 0; 294 } 295 296 return 1; 297} 298 299ENGINE* ENGINE_keystore() { 300 ALOGV("ENGINE_keystore"); 301 302 Unique_ENGINE engine(ENGINE_new()); 303 if (engine.get() == NULL) { 304 return NULL; 305 } 306 307 if (!keystore_engine_setup(engine.get())) { 308 return NULL; 309 } 310 311 return engine.release(); 312} 313 314static int keystore_bind_fn(ENGINE *e, const char *id) { 315 ALOGV("keystore_bind_fn"); 316 317 if (!id) { 318 return 0; 319 } 320 321 if (strcmp(id, KEYSTORE_ENGINE_ID)) { 322 return 0; 323 } 324 325 if (!keystore_engine_setup(e)) { 326 return 0; 327 } 328 329 return 1; 330} 331 332extern "C" { 333#undef OPENSSL_EXPORT 334#define OPENSSL_EXPORT extern __attribute__ ((visibility ("default"))) 335 336IMPLEMENT_DYNAMIC_CHECK_FN() 337IMPLEMENT_DYNAMIC_BIND_FN(keystore_bind_fn) 338}; 339