From e7ff0e0b391341bdc4d9c08dff1c477e1df6a682 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Mon, 21 Dec 2015 19:57:34 +0100 Subject: resolved: properly implement RRSIG validation of wildcarded RRsets Note that this is still not complete, one additional step is still missing: when we verified that a wildcard RRset is properly signed, we still need to do an NSEC/NSEC3 proof that no more specific RRset exists. --- src/resolve/resolved-dns-dnssec.c | 23 +++++++++++++++- src/shared/dns-domain.c | 56 +++++++++++++++++++++++++++++++++++++++ src/shared/dns-domain.h | 6 +++++ src/test/test-dns-domain.c | 42 +++++++++++++++++++++++++++++ 4 files changed, 126 insertions(+), 1 deletion(-) (limited to 'src') diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c index 814cb1c0f9..9ddad38fa6 100644 --- a/src/resolve/resolved-dns-dnssec.c +++ b/src/resolve/resolved-dns-dnssec.c @@ -384,10 +384,17 @@ int dnssec_verify_rrset( gcry_md_write(md, wire_format_name, r); for (k = 0; k < n; k++) { + const char *suffix; size_t l; rr = list[k]; - r = dns_name_to_wire_format(DNS_RESOURCE_KEY_NAME(rr->key), wire_format_name, sizeof(wire_format_name), true); + r = dns_name_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rrsig->rrsig.labels, &suffix); + if (r < 0) + goto finish; + if (r > 0) /* This is a wildcard! */ + gcry_md_write(md, (uint8_t[]) { 1, '*'}, 2); + + r = dns_name_to_wire_format(suffix, wire_format_name, sizeof(wire_format_name), true); if (r < 0) goto finish; gcry_md_write(md, wire_format_name, r); @@ -497,6 +504,8 @@ int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnske } int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) { + int r; + assert(key); assert(rrsig); @@ -509,6 +518,18 @@ int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) if (rrsig->rrsig.type_covered != key->type) return 0; + /* Make sure signer is a parent of the RRset */ + r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(rrsig->key), rrsig->rrsig.signer); + if (r <= 0) + return r; + + /* Make sure the owner name has at least as many labels as the "label" fields indicates. */ + r = dns_name_count_labels(DNS_RESOURCE_KEY_NAME(rrsig->key)); + if (r < 0) + return r; + if (r < rrsig->rrsig.labels) + return 0; + return dns_name_equal(DNS_RESOURCE_KEY_NAME(rrsig->key), DNS_RESOURCE_KEY_NAME(key)); } diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c index c46f7d21b7..f3dbf60395 100644 --- a/src/shared/dns-domain.c +++ b/src/shared/dns-domain.c @@ -1159,3 +1159,59 @@ finish: return 0; } + +int dns_name_suffix(const char *name, unsigned n_labels, const char **ret) { + const char* labels[DNS_N_LABELS_MAX+1]; + unsigned n = 0; + const char *p; + int r; + + assert(name); + assert(ret); + + p = name; + for (;;) { + if (n > DNS_N_LABELS_MAX) + return -EINVAL; + + labels[n] = p; + + r = dns_name_parent(&p); + if (r < 0) + return r; + if (r == 0) + break; + + n++; + } + + if (n < n_labels) + return -EINVAL; + + *ret = labels[n - n_labels]; + return (int) (n - n_labels); +} + +int dns_name_count_labels(const char *name) { + unsigned n = 0; + const char *p; + int r; + + assert(name); + + p = name; + for (;;) { + r = dns_name_parent(&p); + if (r < 0) + return r; + if (r == 0) + break; + + if (n >= DNS_N_LABELS_MAX) + return -EINVAL; + + n++; + } + + return (int) n; +} diff --git a/src/shared/dns-domain.h b/src/shared/dns-domain.h index 02b51832b6..7b509729fb 100644 --- a/src/shared/dns-domain.h +++ b/src/shared/dns-domain.h @@ -42,6 +42,9 @@ /* Maximum length of a full hostname, on the wire, including the final NUL byte */ #define DNS_WIRE_FOMAT_HOSTNAME_MAX 255 +/* Maximum number of labels per valid hostname */ +#define DNS_N_LABELS_MAX 127 + int dns_label_unescape(const char **name, char *dest, size_t sz); int dns_label_unescape_suffix(const char *name, const char **label_end, char *dest, size_t sz); int dns_label_escape(const char *p, size_t l, char *dest, size_t sz); @@ -96,3 +99,6 @@ bool dns_service_name_is_valid(const char *name); int dns_service_join(const char *name, const char *type, const char *domain, char **ret); int dns_service_split(const char *joined, char **name, char **type, char **domain); + +int dns_name_suffix(const char *name, unsigned n_labels, const char **ret); +int dns_name_count_labels(const char *name); diff --git a/src/test/test-dns-domain.c b/src/test/test-dns-domain.c index de003e251c..3a15ea5c06 100644 --- a/src/test/test-dns-domain.c +++ b/src/test/test-dns-domain.c @@ -475,6 +475,46 @@ static void test_dns_name_change_suffix(void) { test_dns_name_change_suffix_one("a", "b", "c", 0, NULL); } +static void test_dns_name_suffix_one(const char *name, unsigned n_labels, const char *result, int ret) { + const char *p = NULL; + + assert_se(ret == dns_name_suffix(name, n_labels, &p)); + assert_se(streq_ptr(p, result)); +} + +static void test_dns_name_suffix(void) { + test_dns_name_suffix_one("foo.bar", 2, "foo.bar", 0); + test_dns_name_suffix_one("foo.bar", 1, "bar", 1); + test_dns_name_suffix_one("foo.bar", 0, "", 2); + test_dns_name_suffix_one("foo.bar", 3, NULL, -EINVAL); + test_dns_name_suffix_one("foo.bar", 4, NULL, -EINVAL); + + test_dns_name_suffix_one("bar", 1, "bar", 0); + test_dns_name_suffix_one("bar", 0, "", 1); + test_dns_name_suffix_one("bar", 2, NULL, -EINVAL); + test_dns_name_suffix_one("bar", 3, NULL, -EINVAL); + + test_dns_name_suffix_one("", 0, "", 0); + test_dns_name_suffix_one("", 1, NULL, -EINVAL); + test_dns_name_suffix_one("", 2, NULL, -EINVAL); +} + +static void test_dns_name_count_labels_one(const char *name, int n) { + assert_se(dns_name_count_labels(name) == n); +} + +static void test_dns_name_count_labels(void) { + test_dns_name_count_labels_one("foo.bar.quux.", 3); + test_dns_name_count_labels_one("foo.bar.quux", 3); + test_dns_name_count_labels_one("foo.bar.", 2); + test_dns_name_count_labels_one("foo.bar", 2); + test_dns_name_count_labels_one("foo.", 1); + test_dns_name_count_labels_one("foo", 1); + test_dns_name_count_labels_one("", 0); + test_dns_name_count_labels_one(".", 0); + test_dns_name_count_labels_one("..", -EINVAL); +} + int main(int argc, char *argv[]) { test_dns_label_unescape(); @@ -495,6 +535,8 @@ int main(int argc, char *argv[]) { test_dns_service_join(); test_dns_service_split(); test_dns_name_change_suffix(); + test_dns_name_suffix(); + test_dns_name_count_labels(); return 0; } -- cgit v1.2.3-54-g00ecf