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|
/* SPDX-License-Identifier: LGPL-2.1+ */
#include "sd-messages.h"
#include "alloc-util.h"
#include "conf-files.h"
#include "def.h"
#include "dns-domain.h"
#include "fd-util.h"
#include "fileio.h"
#include "hexdecoct.h"
#include "nulstr-util.h"
#include "parse-util.h"
#include "resolved-dns-dnssec.h"
#include "resolved-dns-trust-anchor.h"
#include "set.h"
#include "sort-util.h"
#include "string-util.h"
#include "strv.h"
static const char trust_anchor_dirs[] = CONF_PATHS_NULSTR("dnssec-trust-anchors.d");
/* The second DS RR from https://data.iana.org/root-anchors/root-anchors.xml, retrieved February 2017 */
static const uint8_t root_digest2[] =
{ 0xE0, 0x6D, 0x44, 0xB8, 0x0B, 0x8F, 0x1D, 0x39, 0xA9, 0x5C, 0x0B, 0x0D, 0x7C, 0x65, 0xD0, 0x84,
0x58, 0xE8, 0x80, 0x40, 0x9B, 0xBC, 0x68, 0x34, 0x57, 0x10, 0x42, 0x37, 0xC7, 0xF8, 0xEC, 0x8D };
static bool dns_trust_anchor_knows_domain_positive(DnsTrustAnchor *d, const char *name) {
assert(d);
/* Returns true if there's an entry for the specified domain
* name in our trust anchor */
return
hashmap_contains(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_DNSKEY, name)) ||
hashmap_contains(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_DS, name));
}
static int add_root_ksk(
DnsAnswer *answer,
DnsResourceKey *key,
uint16_t key_tag,
uint8_t algorithm,
uint8_t digest_type,
const void *digest,
size_t digest_size) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
int r;
rr = dns_resource_record_new(key);
if (!rr)
return -ENOMEM;
rr->ds.key_tag = key_tag;
rr->ds.algorithm = algorithm;
rr->ds.digest_type = digest_type;
rr->ds.digest_size = digest_size;
rr->ds.digest = memdup(digest, rr->ds.digest_size);
if (!rr->ds.digest)
return -ENOMEM;
r = dns_answer_add(answer, rr, 0, DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
return 0;
}
static int dns_trust_anchor_add_builtin_positive(DnsTrustAnchor *d) {
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
int r;
assert(d);
r = hashmap_ensure_allocated(&d->positive_by_key, &dns_resource_key_hash_ops);
if (r < 0)
return r;
/* Only add the built-in trust anchor if there's neither a DS nor a DNSKEY defined for the root domain. That
* way users have an easy way to override the root domain DS/DNSKEY data. */
if (dns_trust_anchor_knows_domain_positive(d, "."))
return 0;
key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_DS, "");
if (!key)
return -ENOMEM;
answer = dns_answer_new(2);
if (!answer)
return -ENOMEM;
/* Add the currently valid RRs from https://data.iana.org/root-anchors/root-anchors.xml */
r = add_root_ksk(answer, key, 20326, DNSSEC_ALGORITHM_RSASHA256, DNSSEC_DIGEST_SHA256, root_digest2, sizeof(root_digest2));
if (r < 0)
return r;
r = hashmap_put(d->positive_by_key, key, answer);
if (r < 0)
return r;
answer = NULL;
return 0;
}
static int dns_trust_anchor_add_builtin_negative(DnsTrustAnchor *d) {
static const char private_domains[] =
/* RFC 6761 says that .test is a special domain for
* testing and not to be installed in the root zone */
"test\0"
/* RFC 6761 says that these reverse IP lookup ranges
* are for private addresses, and hence should not
* show up in the root zone */
"10.in-addr.arpa\0"
"16.172.in-addr.arpa\0"
"17.172.in-addr.arpa\0"
"18.172.in-addr.arpa\0"
"19.172.in-addr.arpa\0"
"20.172.in-addr.arpa\0"
"21.172.in-addr.arpa\0"
"22.172.in-addr.arpa\0"
"23.172.in-addr.arpa\0"
"24.172.in-addr.arpa\0"
"25.172.in-addr.arpa\0"
"26.172.in-addr.arpa\0"
"27.172.in-addr.arpa\0"
"28.172.in-addr.arpa\0"
"29.172.in-addr.arpa\0"
"30.172.in-addr.arpa\0"
"31.172.in-addr.arpa\0"
"168.192.in-addr.arpa\0"
/* The same, but for IPv6. */
"d.f.ip6.arpa\0"
/* RFC 6762 reserves the .local domain for Multicast
* DNS, it hence cannot appear in the root zone. (Note
* that we by default do not route .local traffic to
* DNS anyway, except when a configured search domain
* suggests so.) */
"local\0"
/* These two are well known, popular private zone
* TLDs, that are blocked from delegation, according
* to:
* http://icannwiki.com/Name_Collision#NGPC_Resolution
*
* There's also ongoing work on making this official
* in an RRC:
* https://www.ietf.org/archive/id/draft-chapin-additional-reserved-tlds-02.txt */
"home\0"
"corp\0"
/* The following four TLDs are suggested for private
* zones in RFC 6762, Appendix G, and are hence very
* unlikely to be made official TLDs any day soon */
"lan\0"
"intranet\0"
"internal\0"
"private\0";
const char *name;
int r;
assert(d);
/* Only add the built-in trust anchor if there's no negative
* trust anchor defined at all. This enables easy overriding
* of negative trust anchors. */
if (set_size(d->negative_by_name) > 0)
return 0;
r = set_ensure_allocated(&d->negative_by_name, &dns_name_hash_ops);
if (r < 0)
return r;
/* We add a couple of domains as default negative trust
* anchors, where it's very unlikely they will be installed in
* the root zone. If they exist they must be private, and thus
* unsigned. */
NULSTR_FOREACH(name, private_domains) {
if (dns_trust_anchor_knows_domain_positive(d, name))
continue;
r = set_put_strdup(&d->negative_by_name, name);
if (r < 0)
return r;
}
return 0;
}
static int dns_trust_anchor_load_positive(DnsTrustAnchor *d, const char *path, unsigned line, const char *s) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
_cleanup_free_ char *domain = NULL, *class = NULL, *type = NULL;
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
DnsAnswer *old_answer = NULL;
const char *p = s;
int r;
assert(d);
assert(line);
r = extract_first_word(&p, &domain, NULL, EXTRACT_UNQUOTE);
if (r < 0)
return log_warning_errno(r, "Unable to parse domain in line %s:%u: %m", path, line);
r = dns_name_is_valid(domain);
if (r < 0)
return log_warning_errno(r, "Failed to check validity of domain name '%s', at line %s:%u, ignoring line: %m", domain, path, line);
if (r == 0) {
log_warning("Domain name %s is invalid, at line %s:%u, ignoring line.", domain, path, line);
return -EINVAL;
}
r = extract_many_words(&p, NULL, 0, &class, &type, NULL);
if (r < 0)
return log_warning_errno(r, "Unable to parse class and type in line %s:%u: %m", path, line);
if (r != 2) {
log_warning("Missing class or type in line %s:%u", path, line);
return -EINVAL;
}
if (!strcaseeq(class, "IN")) {
log_warning("RR class %s is not supported, ignoring line %s:%u.", class, path, line);
return -EINVAL;
}
if (strcaseeq(type, "DS")) {
_cleanup_free_ char *key_tag = NULL, *algorithm = NULL, *digest_type = NULL;
_cleanup_free_ void *dd = NULL;
uint16_t kt;
int a, dt;
size_t l;
r = extract_many_words(&p, NULL, 0, &key_tag, &algorithm, &digest_type, NULL);
if (r < 0) {
log_warning_errno(r, "Failed to parse DS parameters on line %s:%u: %m", path, line);
return -EINVAL;
}
if (r != 3) {
log_warning("Missing DS parameters on line %s:%u", path, line);
return -EINVAL;
}
r = safe_atou16(key_tag, &kt);
if (r < 0)
return log_warning_errno(r, "Failed to parse DS key tag %s on line %s:%u: %m", key_tag, path, line);
a = dnssec_algorithm_from_string(algorithm);
if (a < 0) {
log_warning("Failed to parse DS algorithm %s on line %s:%u", algorithm, path, line);
return -EINVAL;
}
dt = dnssec_digest_from_string(digest_type);
if (dt < 0) {
log_warning("Failed to parse DS digest type %s on line %s:%u", digest_type, path, line);
return -EINVAL;
}
if (isempty(p)) {
log_warning("Missing DS digest on line %s:%u", path, line);
return -EINVAL;
}
r = unhexmem(p, strlen(p), &dd, &l);
if (r < 0) {
log_warning("Failed to parse DS digest %s on line %s:%u", p, path, line);
return -EINVAL;
}
rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DS, domain);
if (!rr)
return log_oom();
rr->ds.key_tag = kt;
rr->ds.algorithm = a;
rr->ds.digest_type = dt;
rr->ds.digest_size = l;
rr->ds.digest = TAKE_PTR(dd);
} else if (strcaseeq(type, "DNSKEY")) {
_cleanup_free_ char *flags = NULL, *protocol = NULL, *algorithm = NULL;
_cleanup_free_ void *k = NULL;
uint16_t f;
size_t l;
int a;
r = extract_many_words(&p, NULL, 0, &flags, &protocol, &algorithm, NULL);
if (r < 0)
return log_warning_errno(r, "Failed to parse DNSKEY parameters on line %s:%u: %m", path, line);
if (r != 3) {
log_warning("Missing DNSKEY parameters on line %s:%u", path, line);
return -EINVAL;
}
if (!streq(protocol, "3")) {
log_warning("DNSKEY Protocol is not 3 on line %s:%u", path, line);
return -EINVAL;
}
r = safe_atou16(flags, &f);
if (r < 0)
return log_warning_errno(r, "Failed to parse DNSKEY flags field %s on line %s:%u", flags, path, line);
if ((f & DNSKEY_FLAG_ZONE_KEY) == 0) {
log_warning("DNSKEY lacks zone key bit set on line %s:%u", path, line);
return -EINVAL;
}
if ((f & DNSKEY_FLAG_REVOKE)) {
log_warning("DNSKEY is already revoked on line %s:%u", path, line);
return -EINVAL;
}
a = dnssec_algorithm_from_string(algorithm);
if (a < 0) {
log_warning("Failed to parse DNSKEY algorithm %s on line %s:%u", algorithm, path, line);
return -EINVAL;
}
if (isempty(p)) {
log_warning("Missing DNSKEY key on line %s:%u", path, line);
return -EINVAL;
}
r = unbase64mem(p, strlen(p), &k, &l);
if (r < 0)
return log_warning_errno(r, "Failed to parse DNSKEY key data %s on line %s:%u", p, path, line);
rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DNSKEY, domain);
if (!rr)
return log_oom();
rr->dnskey.flags = f;
rr->dnskey.protocol = 3;
rr->dnskey.algorithm = a;
rr->dnskey.key_size = l;
rr->dnskey.key = TAKE_PTR(k);
} else {
log_warning("RR type %s is not supported, ignoring line %s:%u.", type, path, line);
return -EINVAL;
}
r = hashmap_ensure_allocated(&d->positive_by_key, &dns_resource_key_hash_ops);
if (r < 0)
return log_oom();
old_answer = hashmap_get(d->positive_by_key, rr->key);
answer = dns_answer_ref(old_answer);
r = dns_answer_add_extend(&answer, rr, 0, DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return log_error_errno(r, "Failed to add trust anchor RR: %m");
r = hashmap_replace(d->positive_by_key, rr->key, answer);
if (r < 0)
return log_error_errno(r, "Failed to add answer to trust anchor: %m");
old_answer = dns_answer_unref(old_answer);
answer = NULL;
return 0;
}
static int dns_trust_anchor_load_negative(DnsTrustAnchor *d, const char *path, unsigned line, const char *s) {
_cleanup_free_ char *domain = NULL;
const char *p = s;
int r;
assert(d);
assert(line);
r = extract_first_word(&p, &domain, NULL, EXTRACT_UNQUOTE);
if (r < 0)
return log_warning_errno(r, "Unable to parse line %s:%u: %m", path, line);
r = dns_name_is_valid(domain);
if (r < 0)
return log_warning_errno(r, "Failed to check validity of domain name '%s', at line %s:%u, ignoring line: %m", domain, path, line);
if (r == 0) {
log_warning("Domain name %s is invalid, at line %s:%u, ignoring line.", domain, path, line);
return -EINVAL;
}
if (!isempty(p)) {
log_warning("Trailing garbage at line %s:%u, ignoring line.", path, line);
return -EINVAL;
}
r = set_ensure_allocated(&d->negative_by_name, &dns_name_hash_ops);
if (r < 0)
return log_oom();
r = set_put(d->negative_by_name, domain);
if (r < 0)
return log_oom();
if (r > 0)
domain = NULL;
return 0;
}
static int dns_trust_anchor_load_files(
DnsTrustAnchor *d,
const char *suffix,
int (*loader)(DnsTrustAnchor *d, const char *path, unsigned n, const char *line)) {
_cleanup_strv_free_ char **files = NULL;
char **f;
int r;
assert(d);
assert(suffix);
assert(loader);
r = conf_files_list_nulstr(&files, suffix, NULL, 0, trust_anchor_dirs);
if (r < 0)
return log_error_errno(r, "Failed to enumerate %s trust anchor files: %m", suffix);
STRV_FOREACH(f, files) {
_cleanup_fclose_ FILE *g = NULL;
unsigned n = 0;
g = fopen(*f, "r");
if (!g) {
if (errno == ENOENT)
continue;
log_warning_errno(errno, "Failed to open '%s', ignoring: %m", *f);
continue;
}
for (;;) {
_cleanup_free_ char *line = NULL;
char *l;
r = read_line(g, LONG_LINE_MAX, &line);
if (r < 0) {
log_warning_errno(r, "Failed to read '%s', ignoring: %m", *f);
break;
}
if (r == 0)
break;
n++;
l = strstrip(line);
if (isempty(l))
continue;
if (*l == ';')
continue;
(void) loader(d, *f, n, l);
}
}
return 0;
}
static int domain_name_cmp(char * const *a, char * const *b) {
return dns_name_compare_func(*a, *b);
}
static int dns_trust_anchor_dump(DnsTrustAnchor *d) {
DnsAnswer *a;
Iterator i;
assert(d);
if (hashmap_isempty(d->positive_by_key))
log_info("No positive trust anchors defined.");
else {
log_info("Positive Trust Anchors:");
HASHMAP_FOREACH(a, d->positive_by_key, i) {
DnsResourceRecord *rr;
DNS_ANSWER_FOREACH(rr, a)
log_info("%s", dns_resource_record_to_string(rr));
}
}
if (set_isempty(d->negative_by_name))
log_info("No negative trust anchors defined.");
else {
_cleanup_free_ char **l = NULL, *j = NULL;
l = set_get_strv(d->negative_by_name);
if (!l)
return log_oom();
typesafe_qsort(l, set_size(d->negative_by_name), domain_name_cmp);
j = strv_join(l, " ");
if (!j)
return log_oom();
log_info("Negative trust anchors: %s", j);
}
return 0;
}
int dns_trust_anchor_load(DnsTrustAnchor *d) {
int r;
assert(d);
/* If loading things from disk fails, we don't consider this fatal */
(void) dns_trust_anchor_load_files(d, ".positive", dns_trust_anchor_load_positive);
(void) dns_trust_anchor_load_files(d, ".negative", dns_trust_anchor_load_negative);
/* However, if the built-in DS fails, then we have a problem. */
r = dns_trust_anchor_add_builtin_positive(d);
if (r < 0)
return log_error_errno(r, "Failed to add built-in positive trust anchor: %m");
r = dns_trust_anchor_add_builtin_negative(d);
if (r < 0)
return log_error_errno(r, "Failed to add built-in negative trust anchor: %m");
dns_trust_anchor_dump(d);
return 0;
}
void dns_trust_anchor_flush(DnsTrustAnchor *d) {
assert(d);
d->positive_by_key = hashmap_free_with_destructor(d->positive_by_key, dns_answer_unref);
d->revoked_by_rr = set_free_with_destructor(d->revoked_by_rr, dns_resource_record_unref);
d->negative_by_name = set_free_free(d->negative_by_name);
}
int dns_trust_anchor_lookup_positive(DnsTrustAnchor *d, const DnsResourceKey *key, DnsAnswer **ret) {
DnsAnswer *a;
assert(d);
assert(key);
assert(ret);
/* We only serve DS and DNSKEY RRs. */
if (!IN_SET(key->type, DNS_TYPE_DS, DNS_TYPE_DNSKEY))
return 0;
a = hashmap_get(d->positive_by_key, key);
if (!a)
return 0;
*ret = dns_answer_ref(a);
return 1;
}
int dns_trust_anchor_lookup_negative(DnsTrustAnchor *d, const char *name) {
int r;
assert(d);
assert(name);
for (;;) {
/* If the domain is listed as-is in the NTA database, then that counts */
if (set_contains(d->negative_by_name, name))
return true;
/* If the domain isn't listed as NTA, but is listed as positive trust anchor, then that counts. See RFC
* 7646, section 1.1 */
if (hashmap_contains(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_DS, name)))
return false;
if (hashmap_contains(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_KEY, name)))
return false;
/* And now, let's look at the parent, and check that too */
r = dns_name_parent(&name);
if (r < 0)
return r;
if (r == 0)
break;
}
return false;
}
static int dns_trust_anchor_revoked_put(DnsTrustAnchor *d, DnsResourceRecord *rr) {
int r;
assert(d);
r = set_ensure_allocated(&d->revoked_by_rr, &dns_resource_record_hash_ops);
if (r < 0)
return r;
r = set_put(d->revoked_by_rr, rr);
if (r < 0)
return r;
if (r > 0)
dns_resource_record_ref(rr);
return r;
}
static int dns_trust_anchor_remove_revoked(DnsTrustAnchor *d, DnsResourceRecord *rr) {
_cleanup_(dns_answer_unrefp) DnsAnswer *new_answer = NULL;
DnsAnswer *old_answer;
int r;
/* Remember that this is a revoked trust anchor RR */
r = dns_trust_anchor_revoked_put(d, rr);
if (r < 0)
return r;
/* Remove this from the positive trust anchor */
old_answer = hashmap_get(d->positive_by_key, rr->key);
if (!old_answer)
return 0;
new_answer = dns_answer_ref(old_answer);
r = dns_answer_remove_by_rr(&new_answer, rr);
if (r <= 0)
return r;
/* We found the key! Warn the user */
log_struct(LOG_WARNING,
"MESSAGE_ID=" SD_MESSAGE_DNSSEC_TRUST_ANCHOR_REVOKED_STR,
LOG_MESSAGE("DNSSEC trust anchor %s has been revoked.\n"
"Please update the trust anchor, or upgrade your operating system.",
strna(dns_resource_record_to_string(rr))),
"TRUST_ANCHOR=%s", dns_resource_record_to_string(rr));
if (dns_answer_size(new_answer) <= 0) {
assert_se(hashmap_remove(d->positive_by_key, rr->key) == old_answer);
dns_answer_unref(old_answer);
return 1;
}
r = hashmap_replace(d->positive_by_key, new_answer->items[0].rr->key, new_answer);
if (r < 0)
return r;
new_answer = NULL;
dns_answer_unref(old_answer);
return 1;
}
static int dns_trust_anchor_check_revoked_one(DnsTrustAnchor *d, DnsResourceRecord *revoked_dnskey) {
DnsAnswer *a;
int r;
assert(d);
assert(revoked_dnskey);
assert(revoked_dnskey->key->type == DNS_TYPE_DNSKEY);
assert(revoked_dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE);
a = hashmap_get(d->positive_by_key, revoked_dnskey->key);
if (a) {
DnsResourceRecord *anchor;
/* First, look for the precise DNSKEY in our trust anchor database */
DNS_ANSWER_FOREACH(anchor, a) {
if (anchor->dnskey.protocol != revoked_dnskey->dnskey.protocol)
continue;
if (anchor->dnskey.algorithm != revoked_dnskey->dnskey.algorithm)
continue;
if (anchor->dnskey.key_size != revoked_dnskey->dnskey.key_size)
continue;
/* Note that we allow the REVOKE bit to be
* different! It will be set in the revoked
* key, but unset in our version of it */
if (((anchor->dnskey.flags ^ revoked_dnskey->dnskey.flags) | DNSKEY_FLAG_REVOKE) != DNSKEY_FLAG_REVOKE)
continue;
if (memcmp(anchor->dnskey.key, revoked_dnskey->dnskey.key, anchor->dnskey.key_size) != 0)
continue;
dns_trust_anchor_remove_revoked(d, anchor);
break;
}
}
a = hashmap_get(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(revoked_dnskey->key->class, DNS_TYPE_DS, dns_resource_key_name(revoked_dnskey->key)));
if (a) {
DnsResourceRecord *anchor;
/* Second, look for DS RRs matching this DNSKEY in our trust anchor database */
DNS_ANSWER_FOREACH(anchor, a) {
/* We set mask_revoke to true here, since our
* DS fingerprint will be the one of the
* unrevoked DNSKEY, but the one we got passed
* here has the bit set. */
r = dnssec_verify_dnskey_by_ds(revoked_dnskey, anchor, true);
if (r < 0)
return r;
if (r == 0)
continue;
dns_trust_anchor_remove_revoked(d, anchor);
break;
}
}
return 0;
}
int dns_trust_anchor_check_revoked(DnsTrustAnchor *d, DnsResourceRecord *dnskey, DnsAnswer *rrs) {
DnsResourceRecord *rrsig;
int r;
assert(d);
assert(dnskey);
/* Looks if "dnskey" is a self-signed RR that has been revoked
* and matches one of our trust anchor entries. If so, removes
* it from the trust anchor and returns > 0. */
if (dnskey->key->type != DNS_TYPE_DNSKEY)
return 0;
/* Is this DNSKEY revoked? */
if ((dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE) == 0)
return 0;
/* Could this be interesting to us at all? If not,
* there's no point in looking for and verifying a
* self-signed RRSIG. */
if (!dns_trust_anchor_knows_domain_positive(d, dns_resource_key_name(dnskey->key)))
return 0;
/* Look for a self-signed RRSIG in the other rrs belonging to this DNSKEY */
DNS_ANSWER_FOREACH(rrsig, rrs) {
DnssecResult result;
if (rrsig->key->type != DNS_TYPE_RRSIG)
continue;
r = dnssec_rrsig_match_dnskey(rrsig, dnskey, true);
if (r < 0)
return r;
if (r == 0)
continue;
r = dnssec_verify_rrset(rrs, dnskey->key, rrsig, dnskey, USEC_INFINITY, &result);
if (r < 0)
return r;
if (result != DNSSEC_VALIDATED)
continue;
/* Bingo! This is a revoked self-signed DNSKEY. Let's
* see if this precise one exists in our trust anchor
* database, too. */
r = dns_trust_anchor_check_revoked_one(d, dnskey);
if (r < 0)
return r;
return 1;
}
return 0;
}
int dns_trust_anchor_is_revoked(DnsTrustAnchor *d, DnsResourceRecord *rr) {
assert(d);
if (!IN_SET(rr->key->type, DNS_TYPE_DS, DNS_TYPE_DNSKEY))
return 0;
return set_contains(d->revoked_by_rr, rr);
}
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