当从 AsyncUDP onPacket 回调中使用 libsodium 解密时触发 ESP32 Stack canary 观察点

Question

从 AsyncUDP onPacket 回调调用解密例程时，我收到“堆栈金丝雀观察点已触发”。未从回调中调用的相同数据的测试解密工作正常。非常感谢任何有关如何解决此问题的帮助。

修剪代码

#define CRYPTO_SALT_BYTES 16
#define CRYPTO_ARGON_OUT_SIZE 32


// Code based on
//https://www.doorbird.com/downloads/api_lan.pdf?rev=0.28
//https://github.com/tsearle/doorbird/blob/master/doorbird.c


AsyncUDP udp1;
AsyncUDP udp2;

typedef struct {
  unsigned char id[3];
  unsigned char version;
  uint32_t opslimit;
  uint32_t memlimit;
  unsigned char salt[16];
  unsigned char nonce[8];
  unsigned char ciphertext[34];
}__attribute__((packed)) NotifyBroadcast;

typedef struct {
  char intercom_id[6];
  char event [8];
  unsigned timestamp;
} __attribute__((packed)) NotifyBroadcastCiphertext;


char * dbuser = "yourUserHere";
char * dbpassword = "yourPWHere";

unsigned int timestamp;

unsigned char* stretchPasswordArgon(const char *password, unsigned char *salt, unsigned *oplimit, unsigned *memlimit) {
  
  if (sodium_is_zero(salt, CRYPTO_SALT_BYTES) ) {
    randombytes_buf(salt, CRYPTO_SALT_BYTES);
    return NULL;
  }
  unsigned char* key = (unsigned char *)malloc(CRYPTO_ARGON_OUT_SIZE);
  
  if (!*oplimit)
    *oplimit = crypto_pwhash_argon2i_OPSLIMIT_INTERACTIVE;

  if (!*memlimit)
    *memlimit = crypto_pwhash_MEMLIMIT_MIN;
 
  if (crypto_pwhash(key, CRYPTO_ARGON_OUT_SIZE, password, strlen(password), salt, *oplimit, *memlimit, crypto_pwhash_ALG_ARGON2I13)) {
    Serial.println("Argon2 Failed");
    *oplimit = 0;
    *memlimit = 0;
    free(key);
    return NULL;
  }
  return key;
}

NotifyBroadcastCiphertext decryptBroadcastNotification(const NotifyBroadcast * notification, const unsigned char* password) {
  
  NotifyBroadcastCiphertext decrypted = {{0},{0},0};

  int res = 0;
  
  if(res = crypto_aead_chacha20poly1305_decrypt((unsigned char*)&decrypted, NULL, NULL, notification->ciphertext, sizeof(notification->ciphertext), NULL, 0, notification->nonce, password))
    Serial.printf("crypto_aead_chacha20poly1305_decrypt() failed %d\n", res);
  
  return decrypted;
}

NotifyBroadcastCiphertext decode_packet(unsigned char * packet, int size, char * password) {
  char truncatedPassword[6];
  NotifyBroadcast * pkt = (NotifyBroadcast*)packet;
  NotifyBroadcastCiphertext decrypted = {{0},{0},0};

  if (size != 70 || pkt->id[0] != 0xDE || pkt->id[1] != 0xAD || pkt->id[2] != 0xBE) {
    return decrypted;

  strncpy(truncatedPassword, password, 5);
  truncatedPassword[5] = 0;
  
  unsigned opslimit = ntohl(pkt->opslimit);
  unsigned memlimit = ntohl(pkt->memlimit);

  unsigned char* stretchPass = stretchPasswordArgon(truncatedPassword, pkt->salt, &opslimit, &memlimit); 
  
  if (stretchPass == NULL)
    Serial.println("Error making stretchpass!\n");
  
  decrypted = decryptBroadcastNotification(pkt, stretchPass);
  
  free(stretchPass);
 
  return decrypted;
}

void handle_event(char * event_str) {
  Serial.printf("Got an event: '%s'\n", event_str);
}

void processPacket(AsyncUDPPacket packet) {

  char intercom_id[10];
  char event_str[10];
  unsigned char* pk = (unsigned char*) malloc(packet.length() + 1);
  memcpy(pk, packet.data(), packet.length());
  
  NotifyBroadcastCiphertext event = decode_packet(pk, packet.length(), dbpassword); 

  free(pk);
  
  if(event.timestamp == 0) 
    return;
  
  strncpy(intercom_id, event.intercom_id, 6);
  intercom_id[6] = 0;
  
  strncpy(event_str, event.event, 8);
  event_str[8] = 0;
  
  if(strncmp(dbuser,intercom_id,6) != 0)
    return;
  
  if(timestamp == event.timestamp)
    return;    
  
  timestamp = event.timestamp; 
  handle_event(event_str); 
}


void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
      delay(500);
      Serial.print(".");
  }
  Serial.println(" CONNECTED");
  
  if (udp1.listen(6524))
  {
    udp1.onPacket([](AsyncUDPPacket packet) {
      processPacket(packet);
    });
  }

  if (udp2.listen(35344))
  {
    udp2.onPacket([](AsyncUDPPacket packet) {
      processPacket(packet);      
    });
  }
}

解码异常如下。

PC: 0x4010da59: blake2b_compress_ref at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_generichash/blake2b/ref/blake2b-compress-ref.c line 73 EXCVADDR: 0x00000000

Decoding stack results 0x4010da56: blake2b_compress_ref at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_generichash/blake2b/ref/blake2b-compress-ref.c line 73 0x4010caa4: crypto_generichash_blake2b__final at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_generichash/blake2b/ref/blake2b-ref.c line 314 0x4010cd69: crypto_generichash_blake2b__blake2b at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_generichash/blake2b/ref/blake2b-ref.c line 367 0x40107395: crypto_generichash_blake2b at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_generichash/blake2b/ref/generichash_blake2b.c line 23 0x4010b039: blake2b_long at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_pwhash/argon2/blake2b-long.c line 61 0x40108216: fill_first_blocks at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_pwhash/argon2/argon2-core.c line 378 0x40108311: initialize at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_pwhash/argon2/argon2-core.c line 509 0x4010d051: argon2_ctx at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_pwhash/argon2/argon2.c line 68 0x4010d0d2: argon2_hash at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_pwhash/argon2/argon2.c line 129 0x4010d172: argon2i_hash_raw at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_pwhash/argon2/argon2.c line 175 0x4010b165: crypto_pwhash_argon2i at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_pwhash/argon2/pwhash_argon2i.c line 168 0x4010725e: crypto_pwhash at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/libsodium/libsodium/src/libsodium/crypto_pwhash/crypto_pwhash.c line 136 0x400d2424: stretchPasswordArgon(char const*, unsigned char*, unsigned int*, unsigned int*) at D:\Code\ArduinoWorkspace\dbesp32/dbesp32.ino line 66 0x400d2582: decode_packet(unsigned char*, int, char*) at D:\Code\ArduinoWorkspace\dbesp32/dbesp32.ino line 118 0x400d26b6: processPacket(AsyncUDPPacket) at D:\Code\ArduinoWorkspace\dbesp32/dbesp32.ino line 158 0x400d283a: std::_Function_handler >::_M_invoke(const std::_Any_data &, AsyncUDPPacket &) at D:\Code\ArduinoWorkspace\dbesp32/dbesp32.ino line 195 0x400d40f1: AsyncUDP::_recv(udp_pcb*, pbuf*, ip_addr const*, unsigned short, netif*) at c:\users\aa\appdata\local\arduino15\packages\esp32\tools\xtensa-esp32-elf-gcc\gcc8_4_0-esp-2021r1\xtensa-esp32-elf\include\c++.4.0\bits/std_function.h line 682 0x400d415d: _udp_task(void*) at D:\Code\ArduinoWorkspace\hardware\espressif\esp32\libraries\AsyncUDP\src\AsyncUDP.cpp line 709

Answer 1

为 async_udp 任务增加 AsyncUDP 库中的分配解决了问题

当从 AsyncUDP onPacket 回调中使用 libsodium 解密时触发 ESP32 Stack canary 观察点

ESP32 Stack canary watchpoint triggered when decrypting with libsodium from an AsyncUDP onPacket Callback

arduino

libsodium

esp32