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[master] Altered v4 lease time handling better handle infinite and large times

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Merged in rt41976
This commit is contained in:
Thomas Markwalder
2017-05-10 13:11:03 -04:00
parent 2c7ccd41f2
commit 68507137e1
4 changed files with 76 additions and 25 deletions
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7
RELNOTES
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@@ -187,6 +187,13 @@ by Eric Young (eay@cryptsoft.com).
Mritunjaykumar Dubey at Nokia for reporting the issue.
[ISC-Bugs #41473]
- Altered DHCPv4 lease time calculation to avoid roll over errors on 64-bit
OS systems when using -1 or large values for default-lease-time. Rollover
values will be replaced with 0x7FFFFFFF - 1. This alleviates unintentionally
short expiration times being handed out when infinite lease times (-1) in
conjuction with failover.
[ISC-Bugs #41976]
Changes since 4.3.0 (bug fixes)
- Tidy up several small tickets.

5
includes/dhcpd.h
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@@ -1588,8 +1588,9 @@ typedef unsigned char option_mask [16];
#define DHCPD_LOG_FACILITY LOG_DAEMON
#endif
#define MAX_TIME 0x7fffffff
#define MIN_TIME 0
#define INFINITE_TIME 0xffffffff
#define MAX_TIME 0x7fffffff
#define MIN_TIME 0
#ifdef USE_LOG_PID
/* include the pid in the syslog messages */

55
server/dhcp.c
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@@ -85,6 +85,8 @@ const int dhcp_type_name_max = ((sizeof dhcp_type_names) / sizeof (char *));
# define send_packet trace_packet_send
#endif
static TIME leaseTimeCheck(TIME calculated, TIME alternate);
void
dhcp (struct packet *packet) {
int ms_nulltp = 0;
@@ -2878,8 +2880,15 @@ void ack_lease (packet, lease, offer, when, msg, ms_nulltp, hp)
* the desired lease time upon renewal.
*/
if (offer == DHCPACK) {
lt->tstp = cur_time + lease_time +
(new_lease_time / 2);
if (lease_time == INFINITE_TIME) {
lt->tstp = MAX_TIME;
} else {
lt->tstp =
leaseTimeCheck(
(cur_time + lease_time
+ (new_lease_time / 2)),
MAX_TIME - 1);
}
/* If we reduced the potential expiry time,
* make sure we don't offer an old-expiry-time
@@ -2896,12 +2905,16 @@ void ack_lease (packet, lease, offer, when, msg, ms_nulltp, hp)
}
#endif /* FAILOVER_PROTOCOL */
/* If the lease duration causes the time value to wrap,
use the maximum expiry time. */
if (cur_time + lease_time < cur_time)
state -> offered_expiry = MAX_TIME - 1;
else
state -> offered_expiry = cur_time + lease_time;
if (lease_time == INFINITE_TIME) {
state->offered_expiry = MAX_TIME;
} else {
/* If the lease duration causes the time value to wrap,
use the maximum expiry time. */
state->offered_expiry
= leaseTimeCheck(cur_time + lease_time,
MAX_TIME - 1);
}
if (when)
lt -> ends = when;
else
@@ -5670,3 +5683,29 @@ reuse_lease (struct packet* packet,
lease->cannot_reuse = (!reusable && offer == DHCPOFFER);
return (reusable);
}
/* \brief Validates a proposed value for use as a lease time
*
* Convenience function used for catching calculeated lease
* times that overflow 4-byte times used in v4 protocol.
*
* We use variables of type TIME in lots of places, which on
* 64-bit systems is 8 bytes while on 32-bit OSs it is int32_t,
* so we have all sorts of fun places to mess things up.
* This function checks a calculated lease time for and if it
* is unsuitable for use as a lease time, the given alternate
* value is returned.
* \param calculated
* \param alternate
*
* \returen either the calculated value if it is valid, or
* the alternate value supplied
*/
TIME leaseTimeCheck(TIME calculated, TIME alternate) {
if ((sizeof(TIME) > 4 && calculated >= INFINITE_TIME) ||
(calculated < cur_time)) {
return (alternate);
}
return (calculated);
}

34
server/dhcpv6.c
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@@ -2090,7 +2090,7 @@ reply_process_ia_na(struct reply_state *reply, struct option_cache *ia) {
* A not included IA ("cleanup" below) could give a Renew/Rebind.
*/
oc = lookup_option(&dhcpv6_universe, packet_ia, D6O_IAADDR);
reply->min_valid = reply->min_prefer = 0xffffffff;
reply->min_valid = reply->min_prefer = INFINITE_TIME;
reply->client_valid = reply->client_prefer = 0;
for (; oc != NULL ; oc = oc->next) {
status = reply_process_addr(reply, oc);
@@ -2845,7 +2845,7 @@ reply_process_ia_ta(struct reply_state *reply, struct option_cache *ia) {
* Deal with an IAADDR for lifetimes.
* For all or none, process IAADDRs as hints.
*/
reply->min_valid = reply->min_prefer = 0xffffffff;
reply->min_valid = reply->min_prefer = INFINITE_TIME;
reply->client_valid = reply->client_prefer = 0;
oc = lookup_option(&dhcpv6_universe, packet_ia, D6O_IAADDR);
for (; oc != NULL; oc = oc->next) {
@@ -3567,10 +3567,10 @@ reply_process_is_addressed(struct reply_state *reply,
* The following doesn't work on at least some systems:
* (cur_time + reply->send_valid < cur_time)
*/
if (reply->send_valid != 0xFFFFFFFF) {
if (reply->send_valid != INFINITE_TIME) {
time_t test_time = cur_time + reply->send_valid;
if (test_time < cur_time)
reply->send_valid = 0xFFFFFFFF;
reply->send_valid = INFINITE_TIME;
}
if (reply->client_prefer == 0)
@@ -3579,7 +3579,7 @@ reply_process_is_addressed(struct reply_state *reply,
reply->send_prefer = reply->client_prefer;
if ((reply->send_prefer >= reply->send_valid) &&
(reply->send_valid != 0xFFFFFFFF))
(reply->send_valid != INFINITE_TIME))
reply->send_prefer = (reply->send_valid / 2) +
(reply->send_valid / 8);
@@ -3634,7 +3634,7 @@ reply_process_is_addressed(struct reply_state *reply,
* when connecting to the lease file MAX_TIME is
*/
if (reply->buf.reply.msg_type == DHCPV6_REPLY) {
if (reply->send_valid == 0xFFFFFFFF) {
if (reply->send_valid == INFINITE_TIME) {
reply->lease->soft_lifetime_end_time = MAX_TIME;
} else {
reply->lease->soft_lifetime_end_time =
@@ -3921,7 +3921,7 @@ reply_process_ia_pd(struct reply_state *reply, struct option_cache *ia) {
* For each prefix in this IA_PD, decide what to do about it.
*/
oc = lookup_option(&dhcpv6_universe, packet_ia, D6O_IAPREFIX);
reply->min_valid = reply->min_prefer = 0xffffffff;
reply->min_valid = reply->min_prefer = INFINITE_TIME;
reply->client_valid = reply->client_prefer = 0;
reply->preflen = -1;
for (; oc != NULL ; oc = oc->next) {
@@ -4813,10 +4813,10 @@ reply_process_is_prefixed(struct reply_state *reply,
* The following doesn't work on at least some systems:
* (cur_time + reply->send_valid < cur_time)
*/
if (reply->send_valid != 0xFFFFFFFF) {
if (reply->send_valid != INFINITE_TIME) {
time_t test_time = cur_time + reply->send_valid;
if (test_time < cur_time)
reply->send_valid = 0xFFFFFFFF;
reply->send_valid = INFINITE_TIME;
}
if (reply->client_prefer == 0)
@@ -4825,7 +4825,7 @@ reply_process_is_prefixed(struct reply_state *reply,
reply->send_prefer = reply->client_prefer;
if ((reply->send_prefer >= reply->send_valid) &&
(reply->send_valid != 0xFFFFFFFF))
(reply->send_valid != INFINITE_TIME))
reply->send_prefer = (reply->send_valid / 2) +
(reply->send_valid / 8);
@@ -4865,7 +4865,7 @@ reply_process_is_prefixed(struct reply_state *reply,
* when connecting to the lease file MAX_TIME is
*/
if (reply->buf.reply.msg_type == DHCPV6_REPLY) {
if (reply->send_valid == 0xFFFFFFFF) {
if (reply->send_valid == INFINITE_TIME) {
reply->lease->soft_lifetime_end_time = MAX_TIME;
} else {
reply->lease->soft_lifetime_end_time =
@@ -8089,8 +8089,10 @@ set_reply_tee_times(struct reply_state* reply, unsigned ia_cursor)
} else if (set_tee_times) {
/* Setting them is enabled so T1 is either infinite or
* 0.5 * the shortest preferred lifetime in the IA_XX */
reply->renew = (reply->min_prefer == 0xFFFFFFFF ? 0xFFFFFFFF
: reply->min_prefer / 2);
if (reply->min_prefer == INFINITE_TIME)
reply->renew = INFINITE_TIME;
else
reply->renew = reply->min_prefer / 2;
} else {
/* Default is to let the client choose */
reply->renew = 0;
@@ -8122,8 +8124,10 @@ set_reply_tee_times(struct reply_state* reply, unsigned ia_cursor)
} else if (set_tee_times) {
/* Setting them is enabled so T2 is either infinite or
* 0.8 * the shortest preferred lifetime in the reply */
reply->rebind = (reply->min_prefer == 0xFFFFFFFF ? 0xFFFFFFFF
: (reply->min_prefer / 5) * 4);
if (reply->min_prefer == INFINITE_TIME)
reply->rebind = INFINITE_TIME;
else
reply->rebind = (reply->min_prefer / 5) * 4;
} else {
/* Default is to let the client choose */
reply->rebind = 0;