DWS/chrony
1
0
Fork 0
mirror of https://gitlab.com/chrony/chrony.git synced 2025-12-03 16:35:06 -05:00
Code Issues Packages Projects Releases Wiki Activity

nts: add server support for authentication with AES-128-GCM-SIV

Browse Source 
Keep a server SIV instance for each available algorithm.

Select AES-128-GCM-SIV if requested by NTS-KE client as the first
supported algorithm.

Instead of encoding the AEAD ID in the cookie, select the algorithm
according to the length of decrypted keys. (This can work as a long as
all supported algorithms use keys with different lengths.)
This commit is contained in:
Miroslav Lichvar
2022-10-11 14:36:14 +02:00
parent cc706b50b9
commit 790a336eb2
4 changed files with 63 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
nts_ntp_server.c
View File

@@ -41,13 +41,15 @@
#include "siv.h"
#include "util.h"
#define SERVER_SIV AEAD_AES_SIV_CMAC_256
#define MAX_SERVER_SIVS 2
struct NtsServer {
SIV_Instance siv;
SIV_Instance sivs[MAX_SERVER_SIVS];
SIV_Algorithm siv_algorithms[MAX_SERVER_SIVS];
unsigned char nonce[NTS_MIN_UNPADDED_NONCE_LENGTH];
NKE_Cookie cookies[NTS_MAX_COOKIES];
int num_cookies;
int siv_index;
NTP_int64 req_tx;
};
@@ -60,6 +62,7 @@ void
NNS_Initialise(void)
{
const char **certs, **keys;
int i;
/* Create an NTS-NTP server instance only if NTS-KE server is enabled */
if (CNF_GetNtsServerCertAndKeyFiles(&certs, &keys) <= 0) {
@@ -68,9 +71,17 @@ NNS_Initialise(void)
}
server = Malloc(sizeof (struct NtsServer));
server->siv = SIV_CreateInstance(SERVER_SIV);
if (!server->siv)
LOG_FATAL("Could not initialise SIV cipher");
server->siv_algorithms[0] = AEAD_AES_SIV_CMAC_256;
server->siv_algorithms[1] = AEAD_AES_128_GCM_SIV;
assert(MAX_SERVER_SIVS == 2);
for (i = 0; i < 2; i++)
server->sivs[i] = SIV_CreateInstance(server->siv_algorithms[i]);
/* AES-SIV-CMAC-256 is required on servers */
if (!server->sivs[0])
LOG_FATAL("Missing AES-SIV-CMAC-256");
}
/* ================================================== */
@@ -78,10 +89,15 @@ NNS_Initialise(void)
void
NNS_Finalise(void)
{
int i;
if (!server)
return;
SIV_DestroyInstance(server->siv);
for (i = 0; i < MAX_SERVER_SIVS; i++) {
if (server->sivs[i])
SIV_DestroyInstance(server->sivs[i]);
}
Free(server);
server = NULL;
}
@@ -96,6 +112,7 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
unsigned char plaintext[NTP_MAX_EXTENSIONS_LENGTH];
NKE_Context context;
NKE_Cookie cookie;
SIV_Instance siv;
void *ef_body;
*kod = 0;
@@ -104,6 +121,7 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
return 0;
server->num_cookies = 0;
server->siv_index = -1;
server->req_tx = packet->transmit_ts;
if (info->ext_fields == 0 || info->mode != MODE_CLIENT)
@@ -163,17 +181,22 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
return 0;
}
if (context.algorithm != SERVER_SIV) {
/* Find the SIV instance needed for authentication */
for (i = 0; i < MAX_SERVER_SIVS && context.algorithm != server->siv_algorithms[i]; i++)
;
if (i == MAX_SERVER_SIVS || !server->sivs[i]) {
DEBUG_LOG("Unexpected SIV");
return 0;
}
server->siv_index = i;
siv = server->sivs[i];
if (!SIV_SetKey(server->siv, context.c2s.key, context.c2s.length)) {
if (!SIV_SetKey(siv, context.c2s.key, context.c2s.length)) {
DEBUG_LOG("Could not set C2S key");
return 0;
}
if (!NNA_DecryptAuthEF(packet, info, server->siv, auth_start,
if (!NNA_DecryptAuthEF(packet, info, siv, auth_start,
plaintext, sizeof (plaintext), &plaintext_length)) {
*kod = NTP_KOD_NTS_NAK;
return 0;
@@ -199,7 +222,7 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
}
}
if (!SIV_SetKey(server->siv, context.s2c.key, context.s2c.length)) {
if (!SIV_SetKey(siv, context.s2c.key, context.s2c.length)) {
DEBUG_LOG("Could not set S2C key");
return 0;
}
@@ -271,9 +294,12 @@ NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,
server->num_cookies = 0;
if (server->siv_index < 0)
return 0;
/* Generate an authenticator field which will make the length
of the response equal to the length of the request */
if (!NNA_GenerateAuthEF(response, res_info, server->siv,
if (!NNA_GenerateAuthEF(response, res_info, server->sivs[server->siv_index],
server->nonce, sizeof (server->nonce),
plaintext, plaintext_length,
req_info->length - res_info->length))