BUG/MAJOR: proxy_protocol: Properly validate TLV lengths
This patch fixes PROXYv2 parsing when the payload of the TCP connection is
fused with the PROXYv2 header within a single recv() call.
Previously HAProxy ignored the PROXYv2 header length when attempting to
parse the TLV, possibly interpreting the first byte of the payload as a
TLV type.
This patch adds proper validation. It ensures that:
1. TLV parsing stops when the end of the PROXYv2 header is reached.
2. TLV lengths cannot exceed the PROXYv2 header length.
3. The PROXYv2 header ends together with the last TLV, not allowing for
"stray bytes" to be ignored.
A reg-test was added to ensure proper behavior.
This patch tries to find the sweat spot between a small and easily
backportable one, and a cleaner one that's more easily adaptable to
older versions, hence why it merges the "if" and "while" blocks which
causes a reindent of the whole block. It should be used as-is for
versions 1.9 to 2.1, the block about PP2_TYPE_AUTHORITY should be
dropped for 2.0 and the block about CRC32C should be dropped for 1.8.
This bug was introduced when TLV parsing was added. This happened in commit
b3e54fe387c7c1ea750f39d3029672d640c499f9. This commit was first released
with HAProxy 1.6-dev1.
A similar issue was fixed in commit 7209c204bd6f3c49132264c7a58f689cdc741c12.
This patch must be backported to HAProxy 1.6+.
(cherry picked from commit 488ee7fb6e4a388bb68153341826a6391da794e9)
[wt: the regtest will fail, it requires 2.2]
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit 6321012472aa910aca7823da45e6eead716f86f5)
[wt: drop the PP2_TYPE_AUTHORITY changes]
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/src/connection.c b/src/connection.c
index bf82f41..5617a1a 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -390,7 +390,7 @@
char *line, *end;
struct proxy_hdr_v2 *hdr_v2;
const char v2sig[] = PP2_SIGNATURE;
- int tlv_length = 0;
+ size_t total_v2_len;
int tlv_offset = 0;
int ret;
@@ -566,7 +566,8 @@
goto fail;
}
- if (trash.data < PP2_HEADER_LEN + ntohs(hdr_v2->len))
+ total_v2_len = PP2_HEADER_LEN + ntohs(hdr_v2->len);
+ if (trash.data < total_v2_len)
goto missing;
switch (hdr_v2->ver_cmd & PP2_CMD_MASK) {
@@ -584,7 +585,6 @@
((struct sockaddr_in *)&conn->addr.to)->sin_port = hdr_v2->addr.ip4.dst_port;
conn->flags |= CO_FL_ADDR_FROM_SET | CO_FL_ADDR_TO_SET;
tlv_offset = PP2_HEADER_LEN + PP2_ADDR_LEN_INET;
- tlv_length = ntohs(hdr_v2->len) - PP2_ADDR_LEN_INET;
break;
case 0x21: /* TCPv6 */
if (ntohs(hdr_v2->len) < PP2_ADDR_LEN_INET6)
@@ -598,41 +598,64 @@
((struct sockaddr_in6 *)&conn->addr.to)->sin6_port = hdr_v2->addr.ip6.dst_port;
conn->flags |= CO_FL_ADDR_FROM_SET | CO_FL_ADDR_TO_SET;
tlv_offset = PP2_HEADER_LEN + PP2_ADDR_LEN_INET6;
- tlv_length = ntohs(hdr_v2->len) - PP2_ADDR_LEN_INET6;
break;
}
/* TLV parsing */
- if (tlv_length > 0) {
- while (tlv_offset + TLV_HEADER_SIZE <= trash.data) {
- const struct tlv *tlv_packet = (struct tlv *) &trash.area[tlv_offset];
- const int tlv_len = get_tlv_length(tlv_packet);
- tlv_offset += tlv_len + TLV_HEADER_SIZE;
+ while (tlv_offset < total_v2_len) {
+ struct tlv *tlv_packet;
+ int tlv_len;
- switch (tlv_packet->type) {
- case PP2_TYPE_CRC32C: {
- void *tlv_crc32c_p = (void *)tlv_packet->value;
- uint32_t n_crc32c = ntohl(read_u32(tlv_crc32c_p));
- write_u32(tlv_crc32c_p, 0);
- if (hash_crc32c(trash.area, PP2_HEADER_LEN + ntohs(hdr_v2->len)) != n_crc32c)
- goto bad_header;
- break;
- }
+ /* Verify that we have at least TLV_HEADER_SIZE bytes left */
+ if (tlv_offset + TLV_HEADER_SIZE > total_v2_len)
+ goto bad_header;
+
+ tlv_packet = (struct tlv *) &trash.area[tlv_offset];
+ tlv_len = get_tlv_length(tlv_packet);
+ tlv_offset += tlv_len + TLV_HEADER_SIZE;
+
+ /* Verify that the TLV length does not exceed the total PROXYv2 length */
+ if (tlv_offset > total_v2_len)
+ goto bad_header;
+
+ switch (tlv_packet->type) {
+ case PP2_TYPE_CRC32C: {
+ uint32_t n_crc32c;
+
+ /* Verify that this TLV is exactly 4 bytes long */
+ if (tlv_len != 4)
+ goto bad_header;
+
+ n_crc32c = read_n32(tlv_packet->value);
+ write_n32(tlv_packet->value, 0); // compute with CRC==0
+
+ if (hash_crc32c(trash.area, total_v2_len) != n_crc32c)
+ goto bad_header;
+ break;
+ }
#ifdef USE_NS
- case PP2_TYPE_NETNS: {
- const struct netns_entry *ns;
- ns = netns_store_lookup((char*)tlv_packet->value, tlv_len);
- if (ns)
- conn->proxy_netns = ns;
- break;
- }
+ case PP2_TYPE_NETNS: {
+ const struct netns_entry *ns;
+
+ ns = netns_store_lookup((char*)tlv_packet->value, tlv_len);
+ if (ns)
+ conn->proxy_netns = ns;
+ break;
+ }
#endif
- default:
- break;
- }
+ default:
+ break;
}
}
+ /* Verify that the PROXYv2 header ends at a TLV boundary.
+ * This is technically unreachable, because the TLV parsing already
+ * verifies that a TLV does not exceed the total length and also
+ * that there is space for a TLV header.
+ */
+ if (tlv_offset != total_v2_len)
+ goto bad_header;
+
/* unsupported protocol, keep local connection address */
break;
case 0x00: /* LOCAL command */
@@ -642,7 +665,7 @@
goto bad_header; /* not a supported command */
}
- trash.data = PP2_HEADER_LEN + ntohs(hdr_v2->len);
+ trash.data = total_v2_len;
goto eat_header;
eat_header: