static int init_esp_ciphers(struct openconnect_info *vpninfo, struct esp *esp,
const EVP_MD *macalg, const EVP_CIPHER *encalg, int decrypt)
{
int ret;
destroy_esp_ciphers(esp);
EVP_CIPHER_CTX_init(&esp->cipher);
if (decrypt)
ret = EVP_DecryptInit_ex(&esp->cipher, encalg, NULL, esp->secrets, NULL);
else
ret = EVP_EncryptInit_ex(&esp->cipher, encalg, NULL, esp->secrets, NULL);
if (!ret) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to initialise ESP cipher:\n"));
openconnect_report_ssl_errors(vpninfo);
return -EIO;
}
EVP_CIPHER_CTX_set_padding(&esp->cipher, 0);
HMAC_CTX_init(&esp->hmac);
if (!HMAC_Init_ex(&esp->hmac, esp->secrets + EVP_CIPHER_key_length(encalg),
EVP_MD_size(macalg), macalg, NULL)) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to initialize ESP HMAC\n"));
openconnect_report_ssl_errors(vpninfo);
destroy_esp_ciphers(esp);
}
esp->seq = 0;
esp->seq_backlog = 0;
return 0;
}
void esp_shutdown(struct openconnect_info *vpninfo)
{
destroy_esp_ciphers(&vpninfo->esp_in[0]);
destroy_esp_ciphers(&vpninfo->esp_in[1]);
destroy_esp_ciphers(&vpninfo->esp_out);
esp_close(vpninfo);
}
int setup_esp_keys(struct openconnect_info *vpninfo)
{
struct esp *esp_in;
const EVP_CIPHER *encalg;
const EVP_MD *macalg;
int ret;
if (vpninfo->dtls_state == DTLS_DISABLED)
return -EOPNOTSUPP;
if (!vpninfo->dtls_addr)
return -EINVAL;
switch (vpninfo->esp_enc) {
case 0x02:
encalg = EVP_aes_128_cbc();
break;
case 0x05:
encalg = EVP_aes_256_cbc();
break;
default:
return -EINVAL;
}
switch (vpninfo->esp_hmac) {
case 0x01:
macalg = EVP_md5();
break;
case 0x02:
macalg = EVP_sha1();
break;
default:
return -EINVAL;
}
vpninfo->old_esp_maxseq = vpninfo->esp_in[vpninfo->current_esp_in].seq + 32;
vpninfo->current_esp_in ^= 1;
esp_in = &vpninfo->esp_in[vpninfo->current_esp_in];
if (!RAND_bytes((void *)&esp_in->spi, sizeof(esp_in->spi)) ||
!RAND_bytes((void *)&esp_in->secrets, sizeof(esp_in->secrets))) {
vpn_progress(vpninfo, PRG_ERR,
_("Failed to generate random keys for ESP:\n"));
openconnect_report_ssl_errors(vpninfo);
return -EIO;
}
ret = init_esp_ciphers(vpninfo, &vpninfo->esp_out, macalg, encalg, 0);
if (ret)
return ret;
ret = init_esp_ciphers(vpninfo, esp_in, macalg, encalg, 1);
if (ret) {
destroy_esp_ciphers(&vpninfo->esp_out);
return ret;
}
if (vpninfo->dtls_state == DTLS_NOSECRET)
vpninfo->dtls_state = DTLS_SECRET;
vpninfo->pkt_trailer = 16 + 20; /* 16 for pad, 20 for HMAC (of which we use 16) */
return 0;
}