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dns-packet: refuse reading overlong DNS names from packets

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Even if we have no problem processing them they are invalid according to
RFC, hence refuse.

Fixes: #34416
This commit is contained in:
Lennart Poettering
2024-10-23 10:22:28 +02:00
parent dfe68da9c4
commit 87d6a9fb2e
2 changed files with 90 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/resolve/resolved-dns-packet.c
+9 -2
View File
@@ -1506,7 +1506,7 @@ int dns_packet_read_name(
size_t after_rindex = 0, jump_barrier = p->rindex;
_cleanup_free_ char *name = NULL;
bool first = true;
size_t n = 0;
size_t n = 0, m = 0;
int r;
if (p->refuse_compression)
@@ -1535,14 +1535,21 @@ int dns_packet_read_name(
if (first)
first = false;
else
else {
name[n++] = '.';
m++;
}
r = dns_label_escape(label, c, name + n, DNS_LABEL_ESCAPED_MAX);
if (r < 0)
return r;
n += r;
m += c;
if (m > DNS_HOSTNAME_MAX)
return -EBADMSG;
continue;
} else if (allow_compression && FLAGS_SET(c, 0xc0)) {
uint16_t ptr;
src/resolve/test-dns-packet-extract.c
+81 -12
View File
@@ -806,12 +806,7 @@ TEST(packet_query_single_long_domain) {
0x10, 'n', 'i', 't', 'r', 'o', 's', 'y', 'l', 's', 'u', 'l', 'f', 'u', 'r', 'i', 'c',
0x10, 'o', 'b', 'j', 'e', 'c', 't', 'l', 'e', 's', 's', 'n', 'e', 's', 's', 'e', 's',
0x10, 'p', 'a', 'r', 't', 'r', 'i', 'd', 'g', 'e', 'b', 'e', 'r', 'r', 'i', 'e', 's',
0x10, 'r', 'e', 'a', 's', 'o', 'n', 'l', 'e', 's', 's', 'n', 'e', 's', 's', 'e', 's',
0x10, 's', 'e', 'm', 'i', 'p', 'a', 't', 'h', 'o', 'l', 'o', 'g', 'i', 'c', 'a', 'l',
0x10, 't', 'o', 'm', 'f', 'o', 'o', 'l', 'i', 's', 'h', 'n', 'e', 's', 's', 'e', 's',
0x10, 'u', 'n', 'd', 'e', 'r', 'c', 'a', 'p', 'i', 't', 'a', 'l', 'i', 'z', 'e', 'd',
0x10, 'v', 'e', 'c', 't', 'o', 'r', 'c', 'a', 'r', 'd', 'i', 'o', 'g', 'r', 'a', 'm',
0x10, 'w', 'e', 'a', 't', 'h', 'e', 'r', 'p', 'r', 'o', 'o', 'f', 'n', 'e', 's', 's',
0x0F, 'r', 'e', 'a', 's', 'o', 'n', 'l', 'e', 's', 's', 'n', 'e', 's', 's', 'e',
0x00,
/* A */ 0x00, 0x01,
/* IN */ 0x00, 0x01
@@ -823,12 +818,12 @@ TEST(packet_query_single_long_domain) {
ASSERT_EQ(dns_question_size(packet->question), 1u);
ASSERT_EQ(dns_answer_size(packet->answer), 0u);
key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_A,
"absorptivenesses.calligraphically.deacidifications.ecophysiological."
"falsifiabilities.heterochromatism.icositetrahedron.journalistically."
"kinaesthetically.lactovegetarians.misinterpretable.nitrosylsulfuric."
"objectlessnesses.partridgeberries.reasonlessnesses.semipathological."
"tomfoolishnesses.undercapitalized.vectorcardiogram.weatherproofness");
key = dns_resource_key_new(
DNS_CLASS_IN, DNS_TYPE_A,
"absorptivenesses.calligraphically.deacidifications.ecophysiological."
"falsifiabilities.heterochromatism.icositetrahedron.journalistically."
"kinaesthetically.lactovegetarians.misinterpretable.nitrosylsulfuric."
"objectlessnesses.partridgeberries.reasonlessnesse");
ASSERT_NOT_NULL(key);
ASSERT_TRUE(dns_question_contains_key(packet->question, key));
@@ -4777,4 +4772,78 @@ TEST(format_dns_svc_param_key) {
ASSERT_STREQ(str, "ohttp");
}
TEST(overlong_domain) {
_cleanup_(dns_packet_unrefp) DnsPacket *packet = NULL;
ASSERT_OK(dns_packet_new(&packet, DNS_PROTOCOL_DNS, 0, DNS_PACKET_SIZE_MAX));
ASSERT_NOT_NULL(packet);
dns_packet_truncate(packet, 0);
const uint8_t data[] = {
0x00, 0x42, 0x00, 0x00,
0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
0x00,
0x00, DNS_TYPE_A,
0x00, DNS_CLASS_IN,
};
ASSERT_OK(dns_packet_append_blob(packet, data, sizeof(data), NULL));
ASSERT_OK(dns_packet_validate_query(packet));
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
ASSERT_ERROR(dns_packet_read_key(packet, &key, NULL, NULL), EBADMSG);
const uint8_t data2[] = {
0x00, 0x42, 0x00, 0x00,
0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
62, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1',
0x00,
0x00, DNS_TYPE_A,
0x00, DNS_CLASS_IN,
};
packet = dns_packet_unref(packet);
ASSERT_OK(dns_packet_new(&packet, DNS_PROTOCOL_DNS, 0, DNS_PACKET_SIZE_MAX));
ASSERT_NOT_NULL(packet);
dns_packet_truncate(packet, 0);
ASSERT_OK(dns_packet_append_blob(packet, data2, sizeof(data2), NULL));
ASSERT_OK(dns_packet_validate_query(packet));
ASSERT_ERROR(dns_packet_read_key(packet, &key, NULL, NULL), EBADMSG);
const uint8_t data3[] = {
0x00, 0x42, 0x00, 0x00,
0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
63, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2',
61, '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0',
0x00,
0x00, DNS_TYPE_A,
0x00, DNS_CLASS_IN,
};
packet = dns_packet_unref(packet);
ASSERT_OK(dns_packet_new(&packet, DNS_PROTOCOL_DNS, 0, DNS_PACKET_SIZE_MAX));
ASSERT_NOT_NULL(packet);
dns_packet_truncate(packet, 0);
ASSERT_OK(dns_packet_append_blob(packet, data3, sizeof(data3), NULL));
ASSERT_OK(dns_packet_validate_query(packet));
ASSERT_OK(dns_packet_read_key(packet, &key, NULL, NULL));
ASSERT_STREQ(dns_resource_key_name(key),
"012345678901234567890123456789012345678901234567890123456789012."
"012345678901234567890123456789012345678901234567890123456789012."
"012345678901234567890123456789012345678901234567890123456789012."
"0123456789012345678901234567890123456789012345678901234567890");
}
DEFINE_TEST_MAIN(LOG_DEBUG)