alex/esp-idf
alex/esp-idf
1
0
Fork 0
mirror of https://github.com/espressif/esp-idf.git synced 2024-09-20 00:36:01 -04:00
Code Issues Actions 3 Packages Projects Releases Wiki Activity

mdns: Fix potential read behind parsed packet

Browse Source
This commit is contained in:
David Cermak 2022-02-02 12:21:12 +01:00
parent 9cbdb8767b
commit 51a5de2525
2 changed files with 48 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

77
components/mdns/mdns.c
View File

@ -332,10 +332,11 @@ static mdns_srv_item_t *_mdns_get_service_item_instance(const char *instance, co
*
* @return the address after the parsed FQDN in the packet or NULL on error
*/
static const uint8_t * _mdns_read_fqdn(const uint8_t * packet, const uint8_t * start, mdns_name_t * name, char * buf)
static const uint8_t * _mdns_read_fqdn(const uint8_t * packet, const uint8_t * start, mdns_name_t * name, char * buf, size_t packet_len)
{
size_t index = 0;
while (start[index]) {
const uint8_t * packet_end = packet + packet_len;
while (start + index < packet_end && start[index]) {
if (name->parts == 4) {
name->invalid = true;
}
@ -347,6 +348,9 @@ static const uint8_t * _mdns_read_fqdn(const uint8_t * packet, const uint8_t * s
}
uint8_t i;
for (i=0; i<len; i++) {
if (start + index >= packet_end) {
return NULL;
}
buf[i] = start[index++];
}
buf[len] = '\0';
@ -369,7 +373,7 @@ static const uint8_t * _mdns_read_fqdn(const uint8_t * packet, const uint8_t * s
//reference address can not be after where we are
return NULL;
}
if (_mdns_read_fqdn(packet, packet + address, name, buf)) {
if (_mdns_read_fqdn(packet, packet + address, name, buf, packet_len)) {
return start + index;
}
return NULL;
@ -569,7 +573,7 @@ static inline int append_one_txt_record_entry(uint8_t * packet, uint16_t * index
*
* @return length of added data: 0 on error or length on success
*/
static uint16_t _mdns_append_fqdn(uint8_t * packet, uint16_t * index, const char * strings[], uint8_t count)
static uint16_t _mdns_append_fqdn(uint8_t * packet, uint16_t * index, const char * strings[], uint8_t count, size_t packet_len)
{
if (!count) {
//empty string so terminate
@ -596,7 +600,7 @@ search_next:
name.service[0] = 0;
name.proto[0] = 0;
name.domain[0] = 0;
const uint8_t * content = _mdns_read_fqdn(packet, len_location, &name, buf);
const uint8_t * content = _mdns_read_fqdn(packet, len_location, &name, buf, packet_len);
if (!content) {
//not a readable fqdn?
return 0;
@ -622,7 +626,7 @@ search_next:
return 0;
}
//run the same for the other strings in the name
return written + _mdns_append_fqdn(packet, index, &strings[1], count - 1);
return written + _mdns_append_fqdn(packet, index, &strings[1], count - 1, packet_len);
}
//we have found the string so let's insert a pointer to it instead
@ -656,7 +660,7 @@ static uint16_t _mdns_append_ptr_record(uint8_t * packet, uint16_t * index, cons
str[2] = proto;
str[3] = MDNS_DEFAULT_DOMAIN;
part_length = _mdns_append_fqdn(packet, index, str + 1, 3);
part_length = _mdns_append_fqdn(packet, index, str + 1, 3, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -669,7 +673,7 @@ static uint16_t _mdns_append_ptr_record(uint8_t * packet, uint16_t * index, cons
record_length += part_length;
uint16_t data_len_location = *index - 2;
part_length = _mdns_append_fqdn(packet, index, str, 4);
part_length = _mdns_append_fqdn(packet, index, str, 4, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -704,7 +708,7 @@ static uint16_t _mdns_append_subtype_ptr_record(uint8_t *packet, uint16_t *index
return 0;
}
part_length = _mdns_append_fqdn(packet, index, subtype_str, ARRAY_SIZE(subtype_str));
part_length = _mdns_append_fqdn(packet, index, subtype_str, ARRAY_SIZE(subtype_str), MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -717,7 +721,7 @@ static uint16_t _mdns_append_subtype_ptr_record(uint8_t *packet, uint16_t *index
record_length += part_length;
uint16_t data_len_location = *index - 2;
part_length = _mdns_append_fqdn(packet, index, instance_str, ARRAY_SIZE(instance_str));
part_length = _mdns_append_fqdn(packet, index, instance_str, ARRAY_SIZE(instance_str), MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -756,7 +760,7 @@ static uint16_t _mdns_append_sdptr_record(uint8_t * packet, uint16_t * index, md
str[1] = service->proto;
str[2] = MDNS_DEFAULT_DOMAIN;
part_length = _mdns_append_fqdn(packet, index, sd_str, 4);
part_length = _mdns_append_fqdn(packet, index, sd_str, 4, MDNS_MAX_PACKET_SIZE);
record_length += part_length;
@ -767,7 +771,7 @@ static uint16_t _mdns_append_sdptr_record(uint8_t * packet, uint16_t * index, md
record_length += part_length;
uint16_t data_len_location = *index - 2;
part_length = _mdns_append_fqdn(packet, index, str, 3);
part_length = _mdns_append_fqdn(packet, index, str, 3, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -805,7 +809,7 @@ static uint16_t _mdns_append_txt_record(uint8_t * packet, uint16_t * index, mdns
return 0;
}
part_length = _mdns_append_fqdn(packet, index, str, 4);
part_length = _mdns_append_fqdn(packet, index, str, 4, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -869,7 +873,7 @@ static uint16_t _mdns_append_srv_record(uint8_t * packet, uint16_t * index, mdns
return 0;
}
part_length = _mdns_append_fqdn(packet, index, str, 4);
part_length = _mdns_append_fqdn(packet, index, str, 4, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -902,7 +906,7 @@ static uint16_t _mdns_append_srv_record(uint8_t * packet, uint16_t * index, mdns
return 0;
}
part_length = _mdns_append_fqdn(packet, index, str, 2);
part_length = _mdns_append_fqdn(packet, index, str, 2, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -935,7 +939,7 @@ static uint16_t _mdns_append_a_record(uint8_t * packet, uint16_t * index, const
return 0;
}
part_length = _mdns_append_fqdn(packet, index, str, 2);
part_length = _mdns_append_fqdn(packet, index, str, 2, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -987,7 +991,7 @@ static uint16_t _mdns_append_aaaa_record(uint8_t * packet, uint16_t * index, con
}
part_length = _mdns_append_fqdn(packet, index, str, 2);
part_length = _mdns_append_fqdn(packet, index, str, 2, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -1035,7 +1039,7 @@ static uint16_t _mdns_append_question(uint8_t * packet, uint16_t * index, mdns_o
str[str_index++] = q->domain;
}
part_length = _mdns_append_fqdn(packet, index, str, str_index);
part_length = _mdns_append_fqdn(packet, index, str, str_index, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
@ -2958,7 +2962,7 @@ static inline uint32_t _mdns_read_u32(const uint8_t * packet, uint16_t index)
*
* @return the address after the parsed FQDN in the packet or NULL on error
*/
static const uint8_t * _mdns_parse_fqdn(const uint8_t * packet, const uint8_t * start, mdns_name_t * name)
static const uint8_t * _mdns_parse_fqdn(const uint8_t * packet, const uint8_t * start, mdns_name_t * name, size_t packet_len)
{
name->parts = 0;
name->sub = 0;
@ -2970,7 +2974,7 @@ static const uint8_t * _mdns_parse_fqdn(const uint8_t * packet, const uint8_t *
static char buf[MDNS_NAME_BUF_LEN];
const uint8_t * next_data = (uint8_t*)_mdns_read_fqdn(packet, start, name, buf);
const uint8_t * next_data = (uint8_t*)_mdns_read_fqdn(packet, start, name, buf, packet_len);
if (!next_data) {
return 0;
}
@ -3243,6 +3247,10 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
mdns_name_t * name = &n;
memset(name, 0, sizeof(mdns_name_t));
if (len <= MDNS_HEAD_ADDITIONAL_OFFSET) {
free(parsed_packet);
return;
}
header.id = _mdns_read_u16(data, MDNS_HEAD_ID_OFFSET);
header.flags.value = _mdns_read_u16(data, MDNS_HEAD_FLAGS_OFFSET);
header.questions = _mdns_read_u16(data, MDNS_HEAD_QUESTIONS_OFFSET);
@ -3274,7 +3282,7 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
uint8_t qs = header.questions;
while (qs--) {
content = _mdns_parse_fqdn(data, content, name);
content = _mdns_parse_fqdn(data, content, name, len);
if (!content) {
header.answers = 0;
header.additional = 0;
@ -3282,6 +3290,9 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
goto clear_rx_packet;//error
}
if (content + MDNS_CLASS_OFFSET + 1 >= data + len) {
goto clear_rx_packet; // malformed packet, won't read behind it
}
uint16_t type = _mdns_read_u16(content, MDNS_TYPE_OFFSET);
uint16_t mdns_class = _mdns_read_u16(content, MDNS_CLASS_OFFSET);
bool unicast = !!(mdns_class & 0x8000);
@ -3353,11 +3364,14 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
while (content < (data + len)) {
content = _mdns_parse_fqdn(data, content, name);
content = _mdns_parse_fqdn(data, content, name, len);
if (!content) {
goto clear_rx_packet;//error
}
if (content + MDNS_LEN_OFFSET + 1 >= data + len) {
goto clear_rx_packet; // malformed packet, won't read behind it
}
uint16_t type = _mdns_read_u16(content, MDNS_TYPE_OFFSET);
uint16_t mdns_class = _mdns_read_u16(content, MDNS_CLASS_OFFSET);
uint32_t ttl = _mdns_read_u32(content, MDNS_TTL_OFFSET);
@ -3403,7 +3417,7 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
}
if (type == MDNS_TYPE_PTR) {
if (!_mdns_parse_fqdn(data, data_ptr, name)) {
if (!_mdns_parse_fqdn(data, data_ptr, name, len)) {
continue;//error
}
if (search_result) {
@ -3442,9 +3456,12 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
}
}
if (!_mdns_parse_fqdn(data, data_ptr + MDNS_SRV_FQDN_OFFSET, name)) {
if (!_mdns_parse_fqdn(data, data_ptr + MDNS_SRV_FQDN_OFFSET, name, len)) {
continue;//error
}
if (data_ptr + MDNS_SRV_PORT_OFFSET + 1 >= data + len) {
goto clear_rx_packet; // malformed packet, won't read behind it
}
uint16_t priority = _mdns_read_u16(data_ptr, MDNS_SRV_PRIORITY_OFFSET);
uint16_t weight = _mdns_read_u16(data_ptr, MDNS_SRV_WEIGHT_OFFSET);
uint16_t port = _mdns_read_u16(data_ptr, MDNS_SRV_PORT_OFFSET);
@ -5852,8 +5869,8 @@ void mdns_debug_packet(const uint8_t * data, size_t len)
uint8_t qs = header.questions;
while (qs--) {
content = _mdns_parse_fqdn(data, content, name);
if (!content) {
content = _mdns_parse_fqdn(data, content, name, len);
if (!content || content + MDNS_CLASS_OFFSET + 1 >= data + len) {
header.answers = 0;
header.additional = 0;
header.servers = 0;
@ -5903,7 +5920,7 @@ void mdns_debug_packet(const uint8_t * data, size_t len)
while (content < (data + len)) {
content = _mdns_parse_fqdn(data, content, name);
content = _mdns_parse_fqdn(data, content, name, len);
if (!content) {
_mdns_dbg_printf("ERROR: parse mdns records\n");
break;
@ -5971,13 +5988,13 @@ void mdns_debug_packet(const uint8_t * data, size_t len)
_mdns_dbg_printf("%u ", ttl);
_mdns_dbg_printf("[%u] ", data_len);
if (type == MDNS_TYPE_PTR) {
if (!_mdns_parse_fqdn(data, data_ptr, name)) {
if (!_mdns_parse_fqdn(data, data_ptr, name, len)) {
_mdns_dbg_printf("ERROR: parse PTR\n");
continue;
}
_mdns_dbg_printf("%s.%s.%s.%s.\n", name->host, name->service, name->proto, name->domain);
} else if (type == MDNS_TYPE_SRV) {
if (!_mdns_parse_fqdn(data, data_ptr + MDNS_SRV_FQDN_OFFSET, name)) {
if (!_mdns_parse_fqdn(data, data_ptr + MDNS_SRV_FQDN_OFFSET, name, len)) {
_mdns_dbg_printf("ERROR: parse SRV\n");
continue;
}
@ -6015,7 +6032,7 @@ void mdns_debug_packet(const uint8_t * data, size_t len)
_mdns_dbg_printf(IPSTR "\n", IP2STR(&ip));
} else if (type == MDNS_TYPE_NSEC) {
const uint8_t * old_ptr = data_ptr;
const uint8_t * new_ptr = _mdns_parse_fqdn(data, data_ptr, name);
const uint8_t * new_ptr = _mdns_parse_fqdn(data, data_ptr, name, len);
if (new_ptr) {
_mdns_dbg_printf("%s.%s.%s.%s. ", name->host, name->service, name->proto, name->domain);
size_t diff = new_ptr - old_ptr;

1
examples/protocols/mdns/mdns_example_test.py
View File

@ -91,6 +91,7 @@ def mdns_server(esp_host):
console_log('Received query: {} '.format(dns.__repr__()))
sock.sendto(get_dns_answer_to_mdns_lwip(TESTER_NAME_LWIP, dns.id), addr)
if len(dns.an) > 0 and dns.an[0].type == dpkt.dns.DNS_A:
console_log('Received answer from {}'.format(dns.an[0].name))
if dns.an[0].name == esp_host + u'.local':
console_log('Received answer to esp32-mdns query: {}'.format(dns.__repr__()))
esp_answered.set()