diff options
Diffstat (limited to 'src/resolve/resolved-dns-trust-anchor.c')
| -rw-r--r-- | src/resolve/resolved-dns-trust-anchor.c | 376 |
1 files changed, 357 insertions, 19 deletions
diff --git a/src/resolve/resolved-dns-trust-anchor.c b/src/resolve/resolved-dns-trust-anchor.c index 03c5b9406e..02d7ac91e1 100644 --- a/src/resolve/resolved-dns-trust-anchor.c +++ b/src/resolve/resolved-dns-trust-anchor.c @@ -19,6 +19,8 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ +#include <sd-messages.h> + #include "alloc-util.h" #include "conf-files.h" #include "def.h" @@ -28,18 +30,30 @@ #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 char trust_anchor_dirs[] = CONF_PATHS_NULSTR("dnssec-trust-anchors.d"); /* The DS RR from https://data.iana.org/root-anchors/root-anchors.xml, retrieved December 2015 */ 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) { +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 dns_trust_anchor_add_builtin_positive(DnsTrustAnchor *d) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; int r; @@ -50,7 +64,11 @@ static int dns_trust_anchor_add_builtin(DnsTrustAnchor *d) { if (r < 0) return r; - if (hashmap_get(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_DS, "."))) + /* 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; /* Add the RR from https://data.iana.org/root-anchors/root-anchors.xml */ @@ -82,6 +100,95 @@ static int dns_trust_anchor_add_builtin(DnsTrustAnchor *d) { 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" + + /* 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; @@ -188,6 +295,14 @@ static int dns_trust_anchor_load_positive(DnsTrustAnchor *d, const char *path, u 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) { @@ -222,7 +337,7 @@ static int dns_trust_anchor_load_positive(DnsTrustAnchor *d, const char *path, u r = hashmap_ensure_allocated(&d->positive_by_key, &dns_resource_key_hash_ops); if (r < 0) - return r; + return log_oom(); old_answer = hashmap_get(d->positive_by_key, rr->key); answer = dns_answer_ref(old_answer); @@ -265,7 +380,7 @@ static int dns_trust_anchor_load_negative(DnsTrustAnchor *d, const char *path, u r = set_ensure_allocated(&d->negative_by_name, &dns_name_hash_ops); if (r < 0) - return r; + return log_oom(); r = set_put(d->negative_by_name, domain); if (r < 0) @@ -326,27 +441,49 @@ static int dns_trust_anchor_load_files( return 0; } -static void dns_trust_anchor_dump(DnsTrustAnchor *d) { +static int domain_name_cmp(const void *a, const void *b) { + char **x = (char**) a, **y = (char**) b; + + return dns_name_compare_func(*x, *y); +} + +static int 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; + 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)); + 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:"); + 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(); + + qsort_safe(l, set_size(d->negative_by_name), sizeof(char*), domain_name_cmp); - SET_FOREACH(n, d->negative_by_name, i) - log_info("%s%s", n, endswith(n, ".") ? "" : "."); + 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) { @@ -359,9 +496,13 @@ int dns_trust_anchor_load(DnsTrustAnchor *d) { (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); + r = dns_trust_anchor_add_builtin_positive(d); if (r < 0) - return log_error_errno(r, "Failed to add trust anchor built-in: %m"); + 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); @@ -370,13 +511,18 @@ int dns_trust_anchor_load(DnsTrustAnchor *d) { void dns_trust_anchor_flush(DnsTrustAnchor *d) { DnsAnswer *a; + DnsResourceRecord *rr; 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); + + while ((rr = set_steal_first(d->revoked_by_rr))) + dns_resource_record_unref(rr); + d->revoked_by_rr = set_free(d->revoked_by_rr); + d->negative_by_name = set_free_free(d->negative_by_name); } @@ -405,3 +551,195 @@ int dns_trust_anchor_lookup_negative(DnsTrustAnchor *d, const char *name) { return set_contains(d->negative_by_name, name); } + +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, + 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; + + /* 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); +} |