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#include "php_snuffleupagus.h"
void generate_key(unsigned char *key) {
PHP_SHA256_CTX ctx;
const char *user_agent = getenv("HTTP_USER_AGENT");
const zend_string *env_var_zend = SPCFG(cookies_env_var);
const zend_string *encryption_key_zend = SPCFG(encryption_key);
const char *env_var = (env_var_zend ? getenv(ZSTR_VAL(env_var_zend)) : NULL);
const char *encryption_key = (encryption_key_zend ? ZSTR_VAL(encryption_key_zend) : NULL);
assert(32 == crypto_secretbox_KEYBYTES); // 32 is the size of a SHA256.
assert(encryption_key); // Encryption key can't be NULL
PHP_SHA256Init(&ctx);
if (user_agent) {
PHP_SHA256Update(&ctx, (const unsigned char *)user_agent, strlen(user_agent));
}
if (env_var) {
PHP_SHA256Update(&ctx, (const unsigned char *)env_var, strlen(env_var));
} else {
sp_log_warn("cookie_encryption",
"The environment variable '%s' "
"is empty, cookies are weakly encrypted",
ZSTR_VAL(env_var_zend));
}
if (encryption_key) {
PHP_SHA256Update(&ctx, (const unsigned char *)encryption_key,
strlen(encryption_key));
}
PHP_SHA256Final((unsigned char *)key, &ctx);
}
// This function return 0 upon success , non-zero otherwise
int decrypt_zval(zval *pDest, bool simulation, zend_hash_key *hash_key) {
unsigned char key[crypto_secretbox_KEYBYTES] = {0};
unsigned char *decrypted = NULL, *backup = NULL;
int ret = 0;
zend_string *debase64 = php_base64_decode((unsigned char *)(Z_STRVAL_P(pDest)), Z_STRLEN_P(pDest));
if (ZSTR_LEN(debase64) < crypto_secretbox_NONCEBYTES) {
if (true == simulation) {
sp_log_simulation(
"cookie_encryption",
"Buffer underflow tentative detected in cookie encryption handling "
"for %s. Using the cookie 'as is' instead of decrypting it",
hash_key ? ZSTR_VAL(hash_key->key) : "the session");
ret = ZEND_HASH_APPLY_KEEP; goto out;
} else {
// LCOV_EXCL_START
sp_log_drop(
"cookie_encryption",
"Buffer underflow (tentative) detected in cookie encryption handling");
ret = ZEND_HASH_APPLY_REMOVE; goto out;
// LCOV_EXCL_STOP
}
}
// LCOV_EXCL_START
if (ZSTR_LEN(debase64) + (size_t)crypto_secretbox_ZEROBYTES <
ZSTR_LEN(debase64)) {
if (true == simulation) {
sp_log_simulation(
"cookie_encryption",
"Integer overflow (tentative) detected in cookie encryption handling "
"for %s. Using the cookie 'as it' instead of decrypting it.",
hash_key ? ZSTR_VAL(hash_key->key) : "the session");
ret = ZEND_HASH_APPLY_KEEP; goto out;
} else {
sp_log_drop(
"cookie_encryption",
"Integer overflow (tentative) detected in cookie encryption handling.");
ret = ZEND_HASH_APPLY_REMOVE; goto out;
}
}
// LCOV_EXCL_STOP
generate_key(key);
decrypted = ecalloc(ZSTR_LEN(debase64) + crypto_secretbox_ZEROBYTES, 1);
backup = ecalloc(ZSTR_LEN(debase64), 1);
memcpy(backup, ZSTR_VAL(debase64), ZSTR_LEN(debase64));
ret = crypto_secretbox_open(
decrypted,
(unsigned char *)(ZSTR_VAL(debase64) + crypto_secretbox_NONCEBYTES),
ZSTR_LEN(debase64) - crypto_secretbox_NONCEBYTES,
(unsigned char *)ZSTR_VAL(debase64), key);
if (-1 == ret) {
if (true == simulation) {
sp_log_simulation(
"cookie_encryption",
"Something went wrong with the decryption of %s. Using the cookie "
"'as is' instead of decrypting it",
hash_key ? ZSTR_VAL(hash_key->key) : "the session");
memcpy(ZSTR_VAL(debase64), backup, ZSTR_LEN(debase64));
ret = ZEND_HASH_APPLY_KEEP; goto out;
} else {
sp_log_warn("cookie_encryption",
"Something went wrong with the decryption of %s",
hash_key ? ZSTR_VAL(hash_key->key) : "the session");
ret = ZEND_HASH_APPLY_REMOVE; goto out;
}
}
ZVAL_STRINGL(pDest, (char *)(decrypted + crypto_secretbox_ZEROBYTES),
ZSTR_LEN(debase64) - crypto_secretbox_NONCEBYTES - 1 -
crypto_secretbox_ZEROBYTES);
ret = ZEND_HASH_APPLY_KEEP;
out:
zend_string_efree(debase64);
efree(decrypted);
efree(backup);
return ret;
}
/*
** This function will return the `data` of length `data_len` encrypted in the
** form `base64(nonce | encrypted_data)` (with `|` being the concatenation
** operation).
*/
zend_string *encrypt_zval(zend_string *data) {
const size_t encrypted_msg_len =
crypto_secretbox_ZEROBYTES + ZSTR_LEN(data) + 1;
// FIXME : We know that this len is too long
const size_t emsg_and_nonce_len =
encrypted_msg_len + crypto_secretbox_NONCEBYTES;
unsigned char key[crypto_secretbox_KEYBYTES] = {0};
unsigned char nonce[crypto_secretbox_NONCEBYTES] = {0};
unsigned char *data_to_encrypt = ecalloc(encrypted_msg_len, 1);
unsigned char *encrypted_data = ecalloc(emsg_and_nonce_len, 1);
generate_key(key);
// Put random bytes in the nonce
php_random_bytes(nonce, sizeof(nonce), 0);
/* tweetnacl's API requires the message to be padded with
crypto_secretbox_ZEROBYTES zeroes. */
memcpy(data_to_encrypt + crypto_secretbox_ZEROBYTES, ZSTR_VAL(data),
ZSTR_LEN(data));
assert(sizeof(zend_long) <= crypto_secretbox_NONCEBYTES);
memcpy(encrypted_data, nonce, crypto_secretbox_NONCEBYTES);
int err = crypto_secretbox(encrypted_data + crypto_secretbox_NONCEBYTES,
data_to_encrypt, encrypted_msg_len, nonce, key);
zend_string *z = NULL;
if (err) {
sp_log_err("cookie_encryption", "something went wrong during encryption");
z = zend_string_init("<sp_encryption_error>", 21, 0);
} else {
z = php_base64_encode(encrypted_data, emsg_and_nonce_len);
}
efree(data_to_encrypt);
efree(encrypted_data);
return z;
}
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