DWS/chrony
1
0
Fork 0
mirror of https://gitlab.com/chrony/chrony.git synced 2025-12-03 16:55:07 -05:00
Code Issues Packages Projects Releases Wiki Activity

ntp: don't send packets with RX/TX timestamp equal to another timestamp

Browse Source 
Before sending a new packet, check if the receive/transmit timestamp
is not equal to the origin timestamp or the previous receive/transmit
timestamp in order to prevent the packet from being its own valid
response (in the symmetric mode) and invalidate responses to the
previous packet.

This improves protection against replay attacks in the symmetric mode.
This commit is contained in:
Miroslav Lichvar
2018-02-20 09:46:08 +01:00
parent f0f18a02a7
commit 2c7ab98370
3 changed files with 49 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
util.c
View File

@@ -726,6 +726,23 @@ UTI_CompareNtp64(NTP_int64 *a, NTP_int64 *b)
/* ================================================== */
int
UTI_IsEqualAnyNtp64(NTP_int64 *a, NTP_int64 *b1, NTP_int64 *b2, NTP_int64 *b3)
{
if (b1 && a->lo == b1->lo && a->hi == b1->hi)
return 1;
if (b2 && a->lo == b2->lo && a->hi == b2->hi)
return 1;
if (b3 && a->lo == b3->lo && a->hi == b3->hi)
return 1;
return 0;
}
/* ================================================== */
/* Seconds part of NTP timestamp correponding to the origin of the time_t format */
#define JAN_1970 0x83aa7e80UL