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ntp: don't accept packets with unexpected authentication

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If authentication is not enabled in configuration, responses are not
expected to be authenticated. Handle such responses as having failed
authentication.

A case where this could happen is a misconfigured symmetric association
where only one peer has specified the other with a key. Before this
change synchronization would work in one direction and used packets
with an asymmetric length.
This commit is contained in:
Miroslav Lichvar 2020-02-03 16:04:08 +01:00
parent 7661a6e95b
commit 5ed9b888ff
2 changed files with 2 additions and 7 deletions
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5
ntp_auth.c
View file

@ -401,11 +401,6 @@ NAU_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *request_info,
int int
NAU_CheckResponseAuth(NAU_Instance instance, NTP_Packet *response, NTP_PacketInfo *info) NAU_CheckResponseAuth(NAU_Instance instance, NTP_Packet *response, NTP_PacketInfo *info)
{ {
/* If we don't expect the packet to be authenticated, ignore any
authentication data in the packet */
if (instance->mode == NTP_AUTH_NONE)
return 1;
/* The authentication must match the expected mode */ /* The authentication must match the expected mode */
if (info->auth.mode != instance->mode) if (info->auth.mode != instance->mode)
return 0; return 0;

4
test/unit/ntp_core.c
View file

@ -356,9 +356,9 @@ test_unit(void)
inst1->tx_count < MAX_CLIENT_INTERLEAVED_TX); inst1->tx_count < MAX_CLIENT_INTERLEAVED_TX);
authenticated = random() % 2; authenticated = random() % 2;
valid = (!interleaved || (source.params.interleaved && has_updated)) && valid = (!interleaved || (source.params.interleaved && has_updated)) &&
(!source.params.authkey || authenticated); ((source.params.authkey == INACTIVE_AUTHKEY) == !authenticated);
updated = (valid || inst1->mode == MODE_ACTIVE) && updated = (valid || inst1->mode == MODE_ACTIVE) &&
(!source.params.authkey || authenticated); ((source.params.authkey == INACTIVE_AUTHKEY) == !authenticated);
has_updated = has_updated || updated; has_updated = has_updated || updated;
if (inst1->mode == MODE_CLIENT) if (inst1->mode == MODE_CLIENT)
updated = 0; updated = 0;