#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 "parse-util.h"

#include "resolved-dns-trust-anchor.h"

#include "resolved-dns-dnssec.h"

#include "set.h"

#include "string-util.h"

#include "strv.h"

static const char trust_anchor_dirs[] = CONF_PATHS_NULSTR("systemd/dnssec-trust-anchors.d");

static const uint8_t root_digest[] =

{ 0x49, 0xAA, 0xC1, 0x1D, 0x7B, 0x6F, 0x64, 0x46, 0x70, 0x2E, 0x54, 0xA1, 0x60, 0x73, 0x71, 0x60,

0x7A, 0x1A, 0x41, 0x85, 0x52, 0x00, 0xFD, 0x2C, 0xE1, 0xCD, 0xDE, 0x32, 0xF2, 0x4E, 0x8F, 0xB5 };

static int dns_trust_anchor_add_builtin(DnsTrustAnchor *d) {

_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;

_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;

int r;

assert(d);

r = hashmap_ensure_allocated(&d->positive_by_key, &dns_resource_key_hash_ops);

if (r < 0)

return r;

if (hashmap_get(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_DS, ".")))

return 0;

/* Add the RR from https://data.iana.org/root-anchors/root-anchors.xml */

rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DS, "");

if (!rr)

return -ENOMEM;

rr->ds.key_tag = 19036;

rr->ds.algorithm = DNSSEC_ALGORITHM_RSASHA256;

rr->ds.digest_type = DNSSEC_DIGEST_SHA256;

rr->ds.digest_size = sizeof(root_digest);

rr->ds.digest = memdup(root_digest, rr->ds.digest_size);

if (!rr->ds.digest)

return -ENOMEM;

answer = dns_answer_new(1);

if (!answer)

return -ENOMEM;

r = dns_answer_add(answer, rr, 0, DNS_ANSWER_AUTHENTICATED);

if (r < 0)

return r;

r = hashmap_put(d->positive_by_key, rr->key, answer);

if (r < 0)

return r;

answer = NULL;

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_QUOTES);

if (r < 0)

return log_warning_errno(r, "Unable to parse domain in line %s:%u: %m", path, line);

if (!dns_name_is_valid(domain)) {

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, *digest = 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, &digest, NULL);

if (r < 0) {

log_warning_errno(r, "Failed to parse DS parameters on line %s:%u: %m", path, line);

return -EINVAL;

}

if (r != 4) {

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;

}

r = unhexmem(digest, strlen(digest), &dd, &l);

if (r < 0) {

log_warning("Failed to parse DS digest %s on line %s:%u", digest, 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 = dd;

dd = NULL;

} else if (strcaseeq(type, "DNSKEY")) {

_cleanup_free_ char *flags = NULL, *protocol = NULL, *algorithm = NULL, *key = NULL;

_cleanup_free_ void *k = NULL;

uint16_t f;

size_t l;

int a;

r = extract_many_words(&p, NULL, 0, &flags, &protocol, &algorithm, &key, NULL);

if (r < 0)

return log_warning_errno(r, "Failed to parse DNSKEY parameters on line %s:%u: %m", path, line);

if (r != 4) {

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;

}

r = unbase64mem(key, strlen(key), &k, &l);

if (r < 0)

return log_warning_errno(r, "Failed to parse DNSKEY key data %s on line %s:%u", key, 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 = k;

k = NULL;

} else {

log_warning("RR type %s is not supported, ignoring line %s:%u.", type, path, line);

return -EINVAL;

}

if (!isempty(p)) {

log_warning("Trailing garbage on line %s:%u, ignoring line.", path, line);

return -EINVAL;

}

r = hashmap_ensure_allocated(&d->positive_by_key, &dns_resource_key_hash_ops);

if (r < 0)

return r;

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_QUOTES);

if (r < 0)

return log_warning_errno(r, "Unable to parse line %s:%u: %m", path, line);

if (!dns_name_is_valid(domain)) {

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 r;

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, 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;

char line[LINE_MAX];

unsigned n = 0;

g = fopen(*f, "r");

if (!g) {

if (errno == ENOENT)

continue;

log_warning_errno(errno, "Failed to open %s: %m", *f);

continue;

}

FOREACH_LINE(line, g, log_warning_errno(errno, "Failed to read %s, ignoring: %m", *f)) {

char *l;

n++;

l = strstrip(line);

if (isempty(l))

continue;

if (*l == ';')

continue;

(void) loader(d, *f, n, l);

}

}

return 0;

}

static void dns_trust_anchor_dump(DnsTrustAnchor *d) {

DnsAnswer *a;

Iterator i;

assert(d);

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)) {

char *n;

log_info("Negative trust anchors:");

SET_FOREACH(n, d->negative_by_name, i)

log_info("%s%s", n, endswith(n, ".") ? "" : ".");

}

}

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(d);

if (r < 0)

return log_error_errno(r, "Failed to add trust anchor built-in: %m");

dns_trust_anchor_dump(d);

return 0;

}

void dns_trust_anchor_flush(DnsTrustAnchor *d) {

DnsAnswer *a;

assert(d);

while ((a = hashmap_steal_first(d->positive_by_key)))

dns_answer_unref(a);

d->positive_by_key = hashmap_free(d->positive_by_key);

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) {

assert(d);

assert(name);

return set_contains(d->negative_by_name, name);

}

static int dns_trust_anchor_remove_revoked(DnsTrustAnchor *d, DnsResourceRecord *rr) {

_cleanup_(dns_answer_unrefp) DnsAnswer *new_answer = NULL;

DnsAnswer *old_answer;

int r;

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,

LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_TRUST_ANCHOR_REVOKED),

LOG_MESSAGE("DNSSEC Trust anchor %s has been revoked. 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),

NULL);

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;

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) {

r = dnssec_verify_dnskey(revoked_dnskey, anchor, true);

if (r < 0)

return r;

if (r == 0)

continue;

dns_trust_anchor_remove_revoked(d, anchor);

break;

}

}

return 0;

}

static bool dns_trust_anchor_knows_domain(DnsTrustAnchor *d, const char *name) {

assert(d);

/* Returns true if there's an entry for the specified domain

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));

}

int dns_trust_anchor_check_revoked(DnsTrustAnchor *d, DnsAnswer *rrs, const DnsResourceKey *key) {

DnsResourceRecord *dnskey;

int r;

assert(d);

assert(key);

/* Looks for self-signed DNSKEY RRs in "rrs" that have been revoked. */

if (key->type != DNS_TYPE_DNSKEY)

return 0;

DNS_ANSWER_FOREACH(dnskey, rrs) {

DnsResourceRecord *rrsig;

DnssecResult result;

r = dns_resource_key_equal(key, dnskey->key);

if (r < 0)

return r;

if (r == 0)

continue;

/* Is this DNSKEY revoked? */

if ((dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE) == 0)

continue;

/* Could this be interesting to us at all? If not,

if (!dns_trust_anchor_knows_domain(d, DNS_RESOURCE_KEY_NAME(dnskey->key)))

continue;

/* Look for a self-signed RRSIG */

DNS_ANSWER_FOREACH(rrsig, rrs) {

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, key, rrsig, dnskey, USEC_INFINITY, &result);

if (r < 0)

return r;

if (result != DNSSEC_VALIDATED)

continue;

/* Bingo! Now, act! */

r = dns_trust_anchor_check_revoked_one(d, dnskey);

if (r < 0)

return r;

}

}

return 0;

}