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X509 time: tighten validation per RFC 5280

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- Reject fractional seconds
- Reject offsets
- Check that the date/time digits are in valid range.
- Add documentation for X509_cmp_time

GH issue 2620

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
This commit is contained in:
Emilia Kasper 2017-02-17 19:00:15 +01:00
parent b169c0ec40
commit 80770da39e
6 changed files with 311 additions and 101 deletions
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5
CHANGES
View File

@ -4,6 +4,11 @@
Changes between 1.1.0e and 1.1.1 [xx XXX xxxx]
*) Certificate time validation (X509_cmp_time) enforces stricter
compliance with RFC 5280. Fractional seconds and timezone offsets
are no longer allowed.
[Emilia Käsper]
*) Add support for SipHash
[Todd Short]

149
crypto/x509/x509_vfy.c
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@ -7,6 +7,7 @@
* https://www.openssl.org/source/license.html
*/
#include <ctype.h>
#include <stdio.h>
#include <time.h>
#include <errno.h>
@ -1754,119 +1755,67 @@ int X509_cmp_current_time(const ASN1_TIME *ctm)
int X509_cmp_time(const ASN1_TIME *ctm, time_t *cmp_time)
{
char *str;
ASN1_TIME atm;
long offset;
char buff1[24], buff2[24], *p;
int i, j, remaining;
static const size_t utctime_length = sizeof("YYMMDDHHMMSSZ") - 1;
static const size_t generalizedtime_length = sizeof("YYYYMMDDHHMMSSZ") - 1;
ASN1_TIME *asn1_cmp_time = NULL;
int i, day, sec, ret = 0;
p = buff1;
remaining = ctm->length;
str = (char *)ctm->data;
/*
* Note that the following (historical) code allows much more slack in the
* time format than RFC5280. In RFC5280, the representation is fixed:
* Note that ASN.1 allows much more slack in the time format than RFC5280.
* In RFC5280, the representation is fixed:
* UTCTime: YYMMDDHHMMSSZ
* GeneralizedTime: YYYYMMDDHHMMSSZ
*
* We do NOT currently enforce the following RFC 5280 requirement:
* "CAs conforming to this profile MUST always encode certificate
* validity dates through the year 2049 as UTCTime; certificate validity
* dates in 2050 or later MUST be encoded as GeneralizedTime."
*/
if (ctm->type == V_ASN1_UTCTIME) {
/* YYMMDDHHMM[SS]Z or YYMMDDHHMM[SS](+-)hhmm */
int min_length = sizeof("YYMMDDHHMMZ") - 1;
int max_length = sizeof("YYMMDDHHMMSS+hhmm") - 1;
if (remaining < min_length || remaining > max_length)
switch (ctm->type) {
case V_ASN1_UTCTIME:
if (ctm->length != (int)(utctime_length))
return 0;
memcpy(p, str, 10);
p += 10;
str += 10;
remaining -= 10;
} else {
/* YYYYMMDDHHMM[SS[.fff]]Z or YYYYMMDDHHMM[SS[.f[f[f]]]](+-)hhmm */
int min_length = sizeof("YYYYMMDDHHMMZ") - 1;
int max_length = sizeof("YYYYMMDDHHMMSS.fff+hhmm") - 1;
if (remaining < min_length || remaining > max_length)
break;
case V_ASN1_GENERALIZEDTIME:
if (ctm->length != (int)(generalizedtime_length))
return 0;
memcpy(p, str, 12);
p += 12;
str += 12;
remaining -= 12;
}
if ((*str == 'Z') || (*str == '-') || (*str == '+')) {
*(p++) = '0';
*(p++) = '0';
} else {
/* SS (seconds) */
if (remaining < 2)
return 0;
*(p++) = *(str++);
*(p++) = *(str++);
remaining -= 2;
/*
* Skip any (up to three) fractional seconds...
* TODO(emilia): in RFC5280, fractional seconds are forbidden.
* Can we just kill them altogether?
*/
if (remaining && *str == '.') {
str++;
remaining--;
for (i = 0; i < 3 && remaining; i++, str++, remaining--) {
if (*str < '0' || *str > '9')
break;
}
}
}
*(p++) = 'Z';
*(p++) = '\0';
/* We now need either a terminating 'Z' or an offset. */
if (!remaining)
break;
default:
return 0;
if (*str == 'Z') {
if (remaining != 1)
return 0;
offset = 0;
} else {
/* (+-)HHMM */
if ((*str != '+') && (*str != '-'))
return 0;
/* Historical behaviour: the (+-)hhmm offset is forbidden in RFC5280. */
if (remaining != 5)
return 0;
if (str[1] < '0' || str[1] > '9' || str[2] < '0' || str[2] > '9' ||
str[3] < '0' || str[3] > '9' || str[4] < '0' || str[4] > '9')
return 0;
offset = ((str[1] - '0') * 10 + (str[2] - '0')) * 60;
offset += (str[3] - '0') * 10 + (str[4] - '0');
if (*str == '-')
offset = -offset;
}
atm.type = ctm->type;
atm.flags = 0;
atm.length = sizeof(buff2);
atm.data = (unsigned char *)buff2;
if (X509_time_adj(&atm, offset * 60, cmp_time) == NULL)
/**
* Verify the format: the ASN.1 functions we use below allow a more
* flexible format than what's mandated by RFC 5280.
* Digit and date ranges will be verified in the conversion methods.
*/
for (i = 0; i < ctm->length - 1; i++) {
if (!isdigit(ctm->data[i]))
return 0;
}
if (ctm->data[ctm->length - 1] != 'Z')
return 0;
if (ctm->type == V_ASN1_UTCTIME) {
i = (buff1[0] - '0') * 10 + (buff1[1] - '0');
if (i < 50)
i += 100; /* cf. RFC 2459 */
j = (buff2[0] - '0') * 10 + (buff2[1] - '0');
if (j < 50)
j += 100;
/*
* There is ASN1_UTCTIME_cmp_time_t but no
* ASN1_GENERALIZEDTIME_cmp_time_t or ASN1_TIME_cmp_time_t,
* so we go through ASN.1
*/
asn1_cmp_time = X509_time_adj(NULL, 0, cmp_time);
if (asn1_cmp_time == NULL)
goto err;
if (!ASN1_TIME_diff(&day, &sec, ctm, asn1_cmp_time))
goto err;
if (i < j)
return -1;
if (i > j)
return 1;
}
i = strcmp(buff1, buff2);
if (i == 0) /* wait a second then return younger :-) */
return -1;
else
return i;
/*
* X509_cmp_time comparison is <=.
* The return value 0 is reserved for errors.
*/
ret = (day >= 0 && sec >= 0) ? -1 : 1;
err:
ASN1_TIME_free(asn1_cmp_time);
return ret;
}
ASN1_TIME *X509_gmtime_adj(ASN1_TIME *s, long adj)

39
doc/man3/X509_cmp_time.pod Normal file
View File

@ -0,0 +1,39 @@
=pod
=head1 NAME
X509_cmp_time - X509 time functions
=head1 SYNOPSIS
X509_cmp_time(const ASN1_TIME *asn1_time, time_t *cmp_time);
=head1 DESCRIPTION
X509_cmp_time() compares the ASN1_TIME in B<asn1_time> with the time in
<cmp_time>.
B<asn1_time> must satisfy the ASN1_TIME format mandated by RFC 5280, i.e.,
its format must be either YYMMDDHHMMSSZ or YYYYMMDDHHMMSSZ.
If B<cmp_time> is NULL the current time is used.
=head1 BUGS
Unlike many standard comparison functions, X509_cmp_time returns 0 on error.
=head1 RETURN VALUES
X509_cmp_time() returns -1 if B<asn1_time> is earlier than, or equal to,
B<cmp_time>, and 1 otherwise. It returns 0 on error.
=head1 COPYRIGHT
Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.
=cut

6
test/build.info
View File

@ -28,7 +28,7 @@ IF[{- !$disabled{tests} -}]
dtlsv1listentest ct_test threadstest afalgtest d2i_test \
ssl_test_ctx_test ssl_test x509aux cipherlist_test asynciotest \
bioprinttest sslapitest dtlstest sslcorrupttest bio_enc_test \
pkey_meth_test uitest cipherbytes_test
pkey_meth_test uitest cipherbytes_test x509_time_test
SOURCE[aborttest]=aborttest.c
INCLUDE[aborttest]=../include
@ -295,6 +295,10 @@ IF[{- !$disabled{tests} -}]
INCLUDE[pkey_meth_test]=../include
DEPEND[pkey_meth_test]=../libcrypto
SOURCE[x509_time_test]=x509_time_test.c testutil.c test_main.c
INCLUDE[x509_time_test]=.. ../include
DEPEND[x509_time_test]=../libcrypto
IF[{- !$disabled{psk} -}]
PROGRAMS_NO_INST=dtls_mtu_test
SOURCE[dtls_mtu_test]=dtls_mtu_test.c ssltestlib.c

12
test/recipes/60-test_x509_time.t Normal file
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@ -0,0 +1,12 @@
#! /usr/bin/env perl
# Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
#
# Licensed under the OpenSSL license (the "License"). You may not use
# this file except in compliance with the License. You can obtain a copy
# in the file LICENSE in the source distribution or at
# https://www.openssl.org/source/license.html
use OpenSSL::Test::Simple;
simple_test("test_x509_time", "x509_time_test");

201
test/x509_time_test.c Normal file
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@ -0,0 +1,201 @@
/*
* Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/* Tests for X509 time functions */
#include <string.h>
#include <time.h>
#include <openssl/asn1.h>
#include <openssl/x509.h>
#include "testutil.h"
#include "test_main.h"
#include "e_os.h"
typedef struct {
const char *data;
int type;
time_t cmp_time;
/* -1 if asn1_time <= cmp_time, 1 if asn1_time > cmp_time, 0 if error. */
int expected;
} TESTDATA;
static TESTDATA x509_cmp_tests[] = {
{
"20170217180154Z", V_ASN1_GENERALIZEDTIME,
/* The same in seconds since epoch. */
1487354514, -1,
},
{
"20170217180154Z", V_ASN1_GENERALIZEDTIME,
/* One second more. */
1487354515, -1,
},
{
"20170217180154Z", V_ASN1_GENERALIZEDTIME,
/* One second less. */
1487354513, 1,
},
/* Same as UTC time. */
{
"170217180154Z", V_ASN1_UTCTIME,
/* The same in seconds since epoch. */
1487354514, -1,
},
{
"170217180154Z", V_ASN1_UTCTIME,
/* One second more. */
1487354515, -1,
},
{
"170217180154Z", V_ASN1_UTCTIME,
/* One second less. */
1487354513, 1,
},
/* UTCTime from the 20th century. */
{
"990217180154Z", V_ASN1_UTCTIME,
/* The same in seconds since epoch. */
919274514, -1,
},
{
"990217180154Z", V_ASN1_UTCTIME,
/* One second more. */
919274515, -1,
},
{
"990217180154Z", V_ASN1_UTCTIME,
/* One second less. */
919274513, 1,
},
/* Various invalid formats. */
{
/* No trailing Z. */
"20170217180154", V_ASN1_GENERALIZEDTIME, 0, 0,
},
{
/* No trailing Z, UTCTime. */
"170217180154", V_ASN1_UTCTIME, 0, 0,
},
{
/* No seconds. */
"201702171801Z", V_ASN1_GENERALIZEDTIME, 0, 0,
},
{
/* No seconds, UTCTime. */
"1702171801Z", V_ASN1_UTCTIME, 0, 0,
},
{
/* Fractional seconds. */
"20170217180154.001Z", V_ASN1_GENERALIZEDTIME, 0, 0,
},
{
/* Fractional seconds, UTCTime. */
"170217180154.001Z", V_ASN1_UTCTIME, 0, 0,
},
{
/* Timezone offset. */
"20170217180154+0100", V_ASN1_GENERALIZEDTIME, 0, 0,
},
{
/* Timezone offset, UTCTime. */
"170217180154+0100", V_ASN1_UTCTIME, 0, 0,
},
{
/* Extra digits. */
"2017021718015400Z", V_ASN1_GENERALIZEDTIME, 0, 0,
},
{
/* Extra digits, UTCTime. */
"17021718015400Z", V_ASN1_UTCTIME, 0, 0,
},
{
/* Non-digits. */
"2017021718015aZ", V_ASN1_GENERALIZEDTIME, 0, 0,
},
{
/* Non-digits, UTCTime. */
"17021718015aZ", V_ASN1_UTCTIME, 0, 0,
},
{
/* Trailing garbage. */
"20170217180154Zlongtrailinggarbage", V_ASN1_GENERALIZEDTIME, 0, 0,
},
{
/* Trailing garbage, UTCTime. */
"170217180154Zlongtrailinggarbage", V_ASN1_UTCTIME, 0, 0,
},
{
/* Swapped type. */
"20170217180154Z", V_ASN1_UTCTIME, 0, 0,
},
{
/* Swapped type. */
"170217180154Z", V_ASN1_GENERALIZEDTIME, 0, 0,
},
{
/* Bad type. */
"20170217180154Z", V_ASN1_OCTET_STRING, 0, 0,
},
};
static int test_x509_cmp_time(int idx)
{
ASN1_TIME t;
int result;
memset(&t, 0, sizeof(t));
t.type = x509_cmp_tests[idx].type;
t.data = (unsigned char*)(x509_cmp_tests[idx].data);
t.length = strlen(x509_cmp_tests[idx].data);
result = X509_cmp_time(&t, &x509_cmp_tests[idx].cmp_time);
if (result != x509_cmp_tests[idx].expected) {
fprintf(stderr, "test_x509_cmp_time(%d) failed: expected %d, got %d\n",
idx, x509_cmp_tests[idx].expected, result);
return 0;
}
return 1;
}
static int test_x509_cmp_time_current()
{
time_t now = time(NULL);
/* Pick a day earlier and later, relative to any system clock. */
ASN1_TIME *asn1_before = NULL, *asn1_after = NULL;
int cmp_result, failed = 0;
asn1_before = ASN1_TIME_adj(NULL, now, -1, 0);
asn1_after = ASN1_TIME_adj(NULL, now, 1, 0);
cmp_result = X509_cmp_time(asn1_before, NULL);
if (cmp_result != -1) {
fprintf(stderr, "test_x509_cmp_time_current failed: expected -1, got %d\n",
cmp_result);
failed = 1;
}
cmp_result = X509_cmp_time(asn1_after, NULL);
if (cmp_result != 1) {
fprintf(stderr, "test_x509_cmp_time_current failed: expected 1, got %d\n",
cmp_result);
failed = 1;
}
ASN1_TIME_free(asn1_before);
ASN1_TIME_free(asn1_after);
return failed == 0;
}
void register_tests()
{
ADD_TEST(test_x509_cmp_time_current);
ADD_ALL_TESTS(test_x509_cmp_time, OSSL_NELEM(x509_cmp_tests));
}