From 5802408ab53a524f40f9a83a104f1d5f19ce5db0 Mon Sep 17 00:00:00 2001 From: Greg Hudson Date: Thu, 24 Aug 2017 16:00:33 -0400 Subject: [PATCH] Limit ticket lifetime to 2^31-1 seconds Although timestamps above 2^31-1 are now valid, intervals exceeding 2^31-1 seconds may be treated incorrectly by comparison operations. The initially computed interval in kdc_get_ticket_endtime() could be negative if the requested end time is far in the future, causing the function to yield an incorrect result. (With the new larger value of kdc_infinity, this could specifically happen if a KDC-REQ contains a zero till field.) Cap the interval at the maximum valid value. Reported by Weijun Wang. Avoid delta comparisons in favor of timestamp comparions in krb5int_validate_times(), ksu's krb5_check_exp(), and clockskew checks. Also use a y2038-safe timestamp comparison in set_request_times() when comparing the requested renewable end time to the requested ticket end time. ticket: 8352 (cherry picked from commit 54e58755368b58ba5894a14c1d02626da42d8003) --- src/clients/ksu/ccache.c | 2 +- src/include/k5-int.h | 7 +++++++ src/kdc/kdc_util.c | 7 ++++++- src/kdc/replay.c | 2 +- src/kdc/t_replay.c | 2 +- src/lib/krb5/krb/gc_via_tkt.c | 4 ++-- src/lib/krb5/krb/get_in_tkt.c | 6 +++--- src/lib/krb5/krb/int-proto.h | 3 --- src/lib/krb5/krb/valid_times.c | 4 ++-- src/lib/krb5/os/timeofday.c | 2 +- 10 files changed, 24 insertions(+), 15 deletions(-) diff --git a/src/clients/ksu/ccache.c b/src/clients/ksu/ccache.c index 236313b7b..2a99521d4 100644 --- a/src/clients/ksu/ccache.c +++ b/src/clients/ksu/ccache.c @@ -282,7 +282,7 @@ krb5_error_code krb5_check_exp(context, tkt_time) } - if (ts_delta(currenttime, tkt_time.endtime) > context->clockskew) { + if (ts_after(currenttime, ts_incr(tkt_time.endtime, context->clockskew))) { retval = KRB5KRB_AP_ERR_TKT_EXPIRED ; return retval; } diff --git a/src/include/k5-int.h b/src/include/k5-int.h index 39ffb9568..e31004a7c 100644 --- a/src/include/k5-int.h +++ b/src/include/k5-int.h @@ -2386,6 +2386,13 @@ ts_after(krb5_timestamp a, krb5_timestamp b) return (uint32_t)a > (uint32_t)b; } +/* Return true if a and b are within d seconds. */ +static inline krb5_boolean +ts_within(krb5_timestamp a, krb5_timestamp b, krb5_deltat d) +{ + return !ts_after(a, ts_incr(b, d)) && !ts_after(b, ts_incr(a, d)); +} + krb5_error_code KRB5_CALLCONV krb5_get_credentials_for_user(krb5_context context, krb5_flags options, krb5_ccache ccache, diff --git a/src/kdc/kdc_util.c b/src/kdc/kdc_util.c index 5455e2a67..770163b94 100644 --- a/src/kdc/kdc_util.c +++ b/src/kdc/kdc_util.c @@ -1759,14 +1759,19 @@ kdc_get_ticket_endtime(kdc_realm_t *kdc_active_realm, krb5_db_entry *server, krb5_timestamp *out_endtime) { - krb5_timestamp until, life; + krb5_timestamp until; + krb5_deltat life; if (till == 0) till = kdc_infinity; until = ts_min(till, endtime); + /* Determine the requested lifetime, capped at the maximum valid time + * interval. */ life = ts_delta(until, starttime); + if (ts_after(until, starttime) && life < 0) + life = INT32_MAX; if (client != NULL && client->max_life != 0) life = min(life, client->max_life); diff --git a/src/kdc/replay.c b/src/kdc/replay.c index fab39cf88..caca783bf 100644 --- a/src/kdc/replay.c +++ b/src/kdc/replay.c @@ -61,7 +61,7 @@ static size_t total_size = 0; static krb5_ui_4 seed; #define STALE_TIME (2*60) /* two minutes */ -#define STALE(ptr, now) (labs(ts_delta((ptr)->timein, now)) >= STALE_TIME) +#define STALE(ptr, now) (ts_after(now, ts_incr((ptr)->timein, STALE_TIME))) /* Return x rotated to the left by r bits. */ static inline krb5_ui_4 diff --git a/src/kdc/t_replay.c b/src/kdc/t_replay.c index 1442e0e8c..bb7e2faff 100644 --- a/src/kdc/t_replay.c +++ b/src/kdc/t_replay.c @@ -903,7 +903,7 @@ test_kdc_insert_lookaside_cache_expire(void **state) assert_non_null(e); e->num_hits = 5; - time_return(STALE_TIME, 0); + time_return(STALE_TIME + 1, 0); kdc_insert_lookaside(context, &req2, NULL); assert_null(K5_LIST_FIRST(&hash_table[req_hash1])); diff --git a/src/lib/krb5/krb/gc_via_tkt.c b/src/lib/krb5/krb/gc_via_tkt.c index cf1ea361f..5b9bb9573 100644 --- a/src/lib/krb5/krb/gc_via_tkt.c +++ b/src/lib/krb5/krb/gc_via_tkt.c @@ -306,8 +306,8 @@ krb5int_process_tgs_reply(krb5_context context, goto cleanup; if (!in_cred->times.starttime && - !in_clock_skew(context, dec_rep->enc_part2->times.starttime, - timestamp)) { + !ts_within(dec_rep->enc_part2->times.starttime, timestamp, + context->clockskew)) { retval = KRB5_KDCREP_SKEW; goto cleanup; } diff --git a/src/lib/krb5/krb/get_in_tkt.c b/src/lib/krb5/krb/get_in_tkt.c index 7178bd87b..ed15550f0 100644 --- a/src/lib/krb5/krb/get_in_tkt.c +++ b/src/lib/krb5/krb/get_in_tkt.c @@ -269,8 +269,8 @@ verify_as_reply(krb5_context context, return retval; } else { if ((request->from == 0) && - !in_clock_skew(context, as_reply->enc_part2->times.starttime, - time_now)) + !ts_within(as_reply->enc_part2->times.starttime, time_now, + context->clockskew)) return (KRB5_KDCREP_SKEW); } return 0; @@ -781,7 +781,7 @@ set_request_times(krb5_context context, krb5_init_creds_context ctx) if (ctx->renew_life > 0) { /* Don't ask for a smaller renewable time than the lifetime. */ ctx->request->rtime = ts_incr(from, ctx->renew_life); - if (ctx->request->rtime < ctx->request->till) + if (ts_after(ctx->request->till, ctx->request->rtime)) ctx->request->rtime = ctx->request->till; ctx->request->kdc_options &= ~KDC_OPT_RENEWABLE_OK; } else { diff --git a/src/lib/krb5/krb/int-proto.h b/src/lib/krb5/krb/int-proto.h index 48bd9f8f7..9c746d05b 100644 --- a/src/lib/krb5/krb/int-proto.h +++ b/src/lib/krb5/krb/int-proto.h @@ -83,9 +83,6 @@ krb5int_construct_matching_creds(krb5_context context, krb5_flags options, krb5_creds *in_creds, krb5_creds *mcreds, krb5_flags *fields); -#define in_clock_skew(context, date, now) \ - (labs(ts_delta(date, now)) < (context)->clockskew) - #define IS_TGS_PRINC(p) ((p)->length == 2 && \ data_eq_string((p)->data[0], KRB5_TGS_NAME)) diff --git a/src/lib/krb5/krb/valid_times.c b/src/lib/krb5/krb/valid_times.c index 9e509b2dd..294761a88 100644 --- a/src/lib/krb5/krb/valid_times.c +++ b/src/lib/krb5/krb/valid_times.c @@ -47,10 +47,10 @@ krb5int_validate_times(krb5_context context, krb5_ticket_times *times) else starttime = times->authtime; - if (ts_delta(starttime, currenttime) > context->clockskew) + if (ts_after(starttime, ts_incr(currenttime, context->clockskew))) return KRB5KRB_AP_ERR_TKT_NYV; /* ticket not yet valid */ - if (ts_delta(currenttime, times->endtime) > context->clockskew) + if (ts_after(currenttime, ts_incr(times->endtime, context->clockskew))) return KRB5KRB_AP_ERR_TKT_EXPIRED; /* ticket expired */ return 0; diff --git a/src/lib/krb5/os/timeofday.c b/src/lib/krb5/os/timeofday.c index 887f24c22..d4e36b1c7 100644 --- a/src/lib/krb5/os/timeofday.c +++ b/src/lib/krb5/os/timeofday.c @@ -60,7 +60,7 @@ krb5_check_clockskew(krb5_context context, krb5_timestamp date) retval = krb5_timeofday(context, ¤ttime); if (retval) return retval; - if (labs(ts_delta(date, currenttime)) >= context->clockskew) + if (!ts_within(date, currenttime, context->clockskew)) return KRB5KRB_AP_ERR_SKEW; return 0;