2adda9c12c
When the NTS client and server negotiated use of AES-128-GCM-SIV keys, the keys exported from the TLS session and used for authentication and encryption of NTP messages do not comply to RFC8915. The exporter context value specified in the section 5.1 of RFC8915 function is incorrect. It is a hardcoded string which contains 15 (AES-SIV-CMAC-256) instead of 30 (AES-128-GCM-SIV). This causes chrony to not interoperate with NTS implementations that follow RFC8915 correctly. (At this time, there doesn't seem to be another implementation with AES-128-GCM-SIV support yet.) Replace the string with a proper construction of the exporter context from a specified AEAD ID and next protocol. Keep using the incorrect AEAD ID for AES-128-GCM-SIV to not break compatibility with existing chrony servers and clients. A new NTS-KE record will be added to negotiate the compliant exporter context. Reported-by: Martin Mayer <martin.mayer@m2-it-solutions.de>
96 lines
3.9 KiB
C
96 lines
3.9 KiB
C
/*
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chronyd/chronyc - Programs for keeping computer clocks accurate.
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**********************************************************************
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* Copyright (C) Miroslav Lichvar 2020
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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**********************************************************************
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=======================================================================
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Header file for the NTS-KE session
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*/
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#ifndef GOT_NTS_KE_SESSION_H
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#define GOT_NTS_KE_SESSION_H
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#include "nts_ke.h"
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#include "siv.h"
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typedef struct NKSN_Credentials_Record *NKSN_Credentials;
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typedef struct NKSN_Instance_Record *NKSN_Instance;
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/* Handler for received NTS-KE messages. A zero return code stops
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the session. */
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typedef int (*NKSN_MessageHandler)(void *arg);
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/* Get server or client credentials using a server certificate and key,
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or certificates of trusted CAs. The credentials may be shared between
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different clients or servers. */
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extern NKSN_Credentials NKSN_CreateServerCertCredentials(const char **certs, const char **keys,
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int n_certs_keys);
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extern NKSN_Credentials NKSN_CreateClientCertCredentials(const char **certs, uint32_t *ids,
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int n_certs_ids,
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uint32_t trusted_cert_set);
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/* Destroy the credentials */
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extern void NKSN_DestroyCertCredentials(NKSN_Credentials credentials);
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/* Create an instance */
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extern NKSN_Instance NKSN_CreateInstance(int server_mode, const char *server_name,
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NKSN_MessageHandler handler, void *handler_arg);
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/* Destroy an instance */
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extern void NKSN_DestroyInstance(NKSN_Instance inst);
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/* Start a new NTS-KE session */
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extern int NKSN_StartSession(NKSN_Instance inst, int sock_fd, const char *label,
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NKSN_Credentials credentials, double timeout);
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/* Begin an NTS-KE message. A request should be made right after starting
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the session and response should be made in the message handler. */
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extern void NKSN_BeginMessage(NKSN_Instance inst);
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/* Add a record to the message */
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extern int NKSN_AddRecord(NKSN_Instance inst, int critical, int type,
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const void *body, int body_length);
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/* Terminate the message */
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extern int NKSN_EndMessage(NKSN_Instance inst);
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/* Get the next record from the received message. This function should be
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called from the message handler. */
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extern int NKSN_GetRecord(NKSN_Instance inst, int *critical, int *type, int *body_length,
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void *body, int buffer_length);
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/* Export NTS keys for a specified algorithm (for compatibility reasons the
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RFC5705 exporter context is allowed to have a different algorithm) */
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extern int NKSN_GetKeys(NKSN_Instance inst, SIV_Algorithm algorithm,
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SIV_Algorithm exporter_algorithm,
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int next_protocol, NKE_Key *c2s, NKE_Key *s2c);
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/* Check if the session has stopped */
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extern int NKSN_IsStopped(NKSN_Instance inst);
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/* Stop the session */
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extern void NKSN_StopSession(NKSN_Instance inst);
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/* Get a factor to calculate retry interval (in log2 seconds)
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based on the session state or how it was terminated */
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extern int NKSN_GetRetryFactor(NKSN_Instance inst);
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#endif
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