1/*
2 * Copyright 2013 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 <utils/UniquePtr.h>
27
28//#define LOG_NDEBUG 0
29#define LOG_TAG "OpenSSL-keystore-dsa"
30#include <cutils/log.h>
31
32#include <binder/IServiceManager.h>
33#include <keystore/IKeystoreService.h>
34
35#include <openssl/dsa.h>
36#include <openssl/engine.h>
37
38#include "methods.h"
39
40
41using namespace android;
42
43struct DSA_SIG_Delete {
44    void operator()(DSA_SIG* p) const {
45        DSA_SIG_free(p);
46    }
47};
48typedef UniquePtr<DSA_SIG, struct DSA_SIG_Delete> Unique_DSA_SIG;
49
50static DSA_SIG* keystore_dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) {
51    ALOGV("keystore_dsa_do_sign(%p, %d, %p)", dgst, dlen, dsa);
52
53    uint8_t* key_id = reinterpret_cast<uint8_t*>(DSA_get_ex_data(dsa, dsa_key_handle));
54    if (key_id == NULL) {
55        ALOGE("key had no key_id!");
56        return 0;
57    }
58
59    sp<IServiceManager> sm = defaultServiceManager();
60    sp<IBinder> binder = sm->getService(String16("android.security.keystore"));
61    sp<IKeystoreService> service = interface_cast<IKeystoreService>(binder);
62
63    if (service == NULL) {
64        ALOGE("could not contact keystore");
65        return 0;
66    }
67
68    int num = DSA_size(dsa);
69
70    uint8_t* reply = NULL;
71    size_t replyLen;
72    int32_t ret = service->sign(String16(reinterpret_cast<const char*>(key_id)), dgst,
73            dlen, &reply, &replyLen);
74    if (ret < 0) {
75        ALOGW("There was an error during dsa_do_sign: could not connect");
76        return 0;
77    } else if (ret != 0) {
78        ALOGW("Error during sign from keystore: %d", ret);
79        return 0;
80    } else if (replyLen <= 0) {
81        ALOGW("No valid signature returned");
82        return 0;
83    } else if (replyLen > (size_t) num) {
84        ALOGW("Signature is too large");
85        return 0;
86    }
87
88    Unique_DSA_SIG dsa_sig(d2i_DSA_SIG(NULL,
89            const_cast<const unsigned char**>(reinterpret_cast<unsigned char**>(&reply)),
90            replyLen));
91    if (dsa_sig.get() == NULL) {
92        ALOGW("conversion from DER to DSA_SIG failed");
93        return 0;
94    }
95
96    ALOGV("keystore_dsa_do_sign(%p, %d, %p) => returning %p len %llu", dgst, dlen, dsa,
97            dsa_sig.get(), replyLen);
98    return dsa_sig.release();
99}
100
101static DSA_METHOD keystore_dsa_meth = {
102        kKeystoreEngineId, /* name */
103        keystore_dsa_do_sign, /* dsa_do_sign */
104        NULL, /* dsa_sign_setup */
105        NULL, /* dsa_do_verify */
106        NULL, /* dsa_mod_exp */
107        NULL, /* bn_mod_exp */
108        NULL, /* init */
109        NULL, /* finish */
110        0, /* flags */
111        NULL, /* app_data */
112        NULL, /* dsa_paramgen */
113        NULL, /* dsa_keygen */
114};
115
116static int register_dsa_methods() {
117    const DSA_METHOD* dsa_meth = DSA_OpenSSL();
118
119    keystore_dsa_meth.dsa_do_verify = dsa_meth->dsa_do_verify;
120
121    return 1;
122}
123
124int dsa_pkey_setup(ENGINE *e, EVP_PKEY *pkey, const char *key_id) {
125    Unique_DSA dsa(EVP_PKEY_get1_DSA(pkey));
126    if (!DSA_set_ex_data(dsa.get(), dsa_key_handle, reinterpret_cast<void*>(strdup(key_id)))) {
127        ALOGW("Could not set ex_data for loaded DSA key");
128        return 0;
129    }
130
131    DSA_set_method(dsa.get(), &keystore_dsa_meth);
132
133    /*
134     * "DSA_set_ENGINE()" should probably be an OpenSSL API. Since it isn't,
135     * and EVP_PKEY_free() calls ENGINE_finish(), we need to call ENGINE_init()
136     * here.
137     */
138    ENGINE_init(e);
139    dsa->engine = e;
140
141    return 1;
142}
143
144int dsa_register(ENGINE* e) {
145    if (!ENGINE_set_DSA(e, &keystore_dsa_meth)
146            || !register_dsa_methods()) {
147        ALOGE("Could not set up keystore DSA methods");
148        return 0;
149    }
150
151    return 1;
152}
153