Mypal/mozglue/android/NSSBridge.cpp

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <stdlib.h>
#include "dlfcn.h"
#include "NSSBridge.h"
#include "APKOpen.h"
#ifdef ANDROID
#include <jni.h>
#include <android/log.h>
#endif

#include "ElfLoader.h"

#ifdef DEBUG
#define LOG(x...) __android_log_print(ANDROID_LOG_INFO, "GeckoJNI", x)
#else
#define LOG(x...)
#endif

static bool initialized = false;

#define NSS_WRAPPER_INT(name) name ## _t f_ ## name;
NSS_WRAPPER_INT(NSS_Initialize)
NSS_WRAPPER_INT(NSS_Shutdown)
NSS_WRAPPER_INT(SECITEM_ZfreeItem)
NSS_WRAPPER_INT(PK11SDR_Encrypt)
NSS_WRAPPER_INT(PK11SDR_Decrypt)
NSS_WRAPPER_INT(PK11_GetInternalKeySlot)
NSS_WRAPPER_INT(PK11_NeedUserInit)
NSS_WRAPPER_INT(PK11_InitPin)
NSS_WRAPPER_INT(PR_ErrorToString)
NSS_WRAPPER_INT(PR_GetError)
NSS_WRAPPER_INT(PR_Free)
NSS_WRAPPER_INT(PL_Base64Encode)
NSS_WRAPPER_INT(PL_Base64Decode)
NSS_WRAPPER_INT(PL_strfree)

SECStatus doCrypto(JNIEnv* jenv, const char *path, const char *value, char** result, bool doEncrypt);
SECStatus encode(const uint8_t* data, uint32_t srclen, char** result);
SECStatus decode(const char* data, uint8_t** result, uint32_t* length);

int
setup_nss_functions(void *nss_handle,
                        void *nspr_handle,
                        void *plc_handle)
{
  if (nss_handle == nullptr || nspr_handle == nullptr || plc_handle == nullptr) {
    LOG("Missing handle\n");
    return FAILURE;
  }
#define GETFUNC(name) f_ ## name = (name ## _t) (uintptr_t) __wrap_dlsym(nss_handle, #name); \
  if (!f_ ##name) { __android_log_print(ANDROID_LOG_ERROR, "GeckoJNI", "missing %s", #name);  return FAILURE; }
  GETFUNC(NSS_Initialize);
  GETFUNC(NSS_Shutdown);
  GETFUNC(PK11SDR_Encrypt);
  GETFUNC(PK11SDR_Decrypt);
  GETFUNC(PK11_GetInternalKeySlot);
  GETFUNC(PK11_NeedUserInit);
  GETFUNC(PK11_InitPin);
  GETFUNC(SECITEM_ZfreeItem);
#undef GETFUNC
#define NSPRFUNC(name) f_ ## name = (name ## _t) (uintptr_t) __wrap_dlsym(nspr_handle, #name); \
  if (!f_ ##name) { __android_log_print(ANDROID_LOG_ERROR, "GeckoJNI", "missing %s", #name);  return FAILURE; }
  NSPRFUNC(PR_ErrorToString);
  NSPRFUNC(PR_GetError);
  NSPRFUNC(PR_Free);
#undef NSPRFUNC
#define PLCFUNC(name) f_ ## name = (name ## _t) (uintptr_t) __wrap_dlsym(plc_handle, #name); \
  if (!f_ ##name) { __android_log_print(ANDROID_LOG_ERROR, "GeckoJNI", "missing %s", #name);  return FAILURE; }
  PLCFUNC(PL_Base64Encode);
  PLCFUNC(PL_Base64Decode);
  PLCFUNC(PL_strfree);
#undef PLCFUNC

  return SUCCESS;
}

/* Throws the current NSS error. */
static void
throwError(JNIEnv* jenv, const char * funcString) {
    char *msg;

    PRErrorCode perr = f_PR_GetError();
    char * errString = f_PR_ErrorToString(perr, 0);
    asprintf(&msg, "%s returned error %d: %s\n", funcString, perr, errString);
    LOG("Throwing error: %s\n", msg);

    JNI_Throw(jenv, "java/lang/Exception", msg);
    free(msg);
    LOG("Error thrown\n");
}

extern "C" NS_EXPORT jstring MOZ_JNICALL
Java_org_mozilla_gecko_NSSBridge_nativeEncrypt(JNIEnv* jenv, jclass,
                                               jstring jPath,
                                               jstring jValue)
{
    jstring ret = jenv->NewStringUTF("");

    const char* path;
    path = jenv->GetStringUTFChars(jPath, nullptr);

    const char* value;
    value = jenv->GetStringUTFChars(jValue, nullptr);

    char* result;
    SECStatus rv = doCrypto(jenv, path, value, &result, true);
    if (rv == SECSuccess) {
      ret = jenv->NewStringUTF(result);
      free(result);
    }

    jenv->ReleaseStringUTFChars(jValue, value);
    jenv->ReleaseStringUTFChars(jPath, path);

    return ret;
}

extern "C" NS_EXPORT jstring MOZ_JNICALL
Java_org_mozilla_gecko_NSSBridge_nativeDecrypt(JNIEnv* jenv, jclass,
                                               jstring jPath,
                                               jstring jValue)
{
    jstring ret = jenv->NewStringUTF("");

    const char* path;
    path = jenv->GetStringUTFChars(jPath, nullptr);

    const char* value;
    value = jenv->GetStringUTFChars(jValue, nullptr);

    char* result;
    SECStatus rv = doCrypto(jenv, path, value, &result, false);
    if (rv == SECSuccess) {
      ret = jenv->NewStringUTF(result);
      free(result);
    }

    jenv->ReleaseStringUTFChars(jValue, value);
    jenv->ReleaseStringUTFChars(jPath, path);

    return ret;
}


/* Encrypts or decrypts a string. result should be freed with free() when done */
SECStatus
doCrypto(JNIEnv* jenv, const char *path, const char *value, char** result, bool encrypt)
{
    SECStatus rv;
    PK11SlotInfo *slot;
    if (!initialized) {
      LOG("Initialize crypto in %s\n", path);
      rv = f_NSS_Initialize(path, "", "", "secmod.db", NSS_INIT_NOROOTINIT);
      if (rv != SECSuccess) {
          throwError(jenv, "NSS_Initialize");
          return rv;
      }
      initialized = true;
    }

    slot = f_PK11_GetInternalKeySlot();
    if (!slot) {
      throwError(jenv, "PK11_GetInternalKeySlot");
      return SECFailure;
    }

    if (f_PK11_NeedUserInit(slot)) {
      LOG("Initializing key3.db with default blank password.\n");
      rv = f_PK11_InitPin(slot, nullptr, nullptr);
      if (rv != SECSuccess) {
        throwError(jenv, "PK11_InitPin");
        return rv;
      }
    }

    SECItem request;
    SECItem reply;

    reply.data = 0;
    reply.len = 0;

    if (encrypt) {
      // This can print sensitive data. Uncomment if you need it.
      // LOG("Encrypting: %s\n", value);
      request.data = (unsigned char*)value;
      request.len = strlen(value);

      SECItem keyid;
      keyid.data = 0;
      keyid.len = 0;
      rv = f_PK11SDR_Encrypt(&keyid, &request, &reply, nullptr);

      if (rv == SECSuccess) {
        rv = encode(reply.data, reply.len, result);
        if (rv == SECSuccess) {
          LOG("Encrypted: %s\n", *result);
        } else {
          throwError(jenv, "encode");
        }
      } else {
        throwError(jenv, "PK11SDR_Encrypt");
      }

    } else {
      LOG("Decoding: %s\n", value);
      rv = decode(value, &request.data, &request.len);
      if (rv != SECSuccess) {
          throwError(jenv, "decode");
          return rv;
      }

      rv = f_PK11SDR_Decrypt(&request, &reply, nullptr);

      if (rv == SECSuccess) {
        *result = static_cast<char*>(malloc(reply.len + 1));
        strncpy(*result, reinterpret_cast<char*>(reply.data), reply.len);
        (*result)[reply.len] = '\0';

        // This can print sensitive data. Uncomment if you need it.
        // LOG("Decoded %i letters: %s\n", reply.len, *result);
      } else {
        throwError(jenv, "PK11SDR_Decrypt");
      }
      free(request.data);
    }

    f_SECITEM_ZfreeItem(&reply, false);
    return rv;
}

/*
 * Base64 encodes the data passed in. The caller must deallocate _retval using free();
 */
SECStatus
encode(const uint8_t* data, uint32_t srclen, char** result)
{
  if (srclen > (PR_UINT32_MAX / 4) * 3) {
    return SECFailure;
  }

  const uint32_t dstlen = ((srclen + 2) / 3) * 4;
  char* const buffer = static_cast<char*>(malloc(dstlen + 1));

  if (!buffer || !f_PL_Base64Encode(reinterpret_cast<const char*>(data), srclen, buffer)) {
    free(buffer);
    *result = nullptr;
    return SECFailure;
  }

  buffer[dstlen] = '\0';
  *result = buffer;
  return SECSuccess;
}

/*
 * Base64 decodes the data passed in. The caller must deallocate result using free();
 */
SECStatus
decode(const char* data, uint8_t** result, uint32_t* length)
{
  uint32_t srclen = strlen(data);
  while (srclen && data[srclen - 1] == '=') {
    srclen--;
  }

  // Avoid overflow when calculating result length.
  const uint32_t dstlen = (srclen / 4) * 3 + ((srclen % 4) * 3) / 4;
  // At most 2 extra bytes due to padding in input.
  uint8_t* const buffer = static_cast<uint8_t*>(malloc(dstlen + 2));

  if (!buffer || !f_PL_Base64Decode(data, srclen, reinterpret_cast<char*>(buffer))) {
    free(buffer);
    *result = nullptr;
    *length = 0;
    return SECFailure;
  }

  buffer[dstlen] = '\0';
  *result = buffer;
  *length = dstlen;
  return SECSuccess;
}