gecko-dev/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" APKOPEN_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" APKOPEN_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;
}