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+.
diff --git a/reg-tests/connection/proxy_protocol_tlv_validation.vtc b/reg-tests/connection/proxy_protocol_tlv_validation.vtc
new file mode 100644
index 0000000..65a251c
--- /dev/null
+++ b/reg-tests/connection/proxy_protocol_tlv_validation.vtc
@@ -0,0 +1,138 @@
+varnishtest "Check that the TLVs are properly validated"
+
+feature ignore_unknown_macro
+
+# We need one HAProxy for each test, because apparently the connection by
+# the client is reused, leading to connection resets.
+
+haproxy h1 -conf {
+ defaults
+ mode http
+ timeout connect 1s
+ timeout client 1s
+ timeout server 1s
+
+ frontend a
+ bind "fd@${fe1}" accept-proxy
+ http-after-response set-header echo %[fc_pp_authority,hex]
+ http-request return status 200
+} -start
+
+# Validate that a correct header passes
+client c1 -connect ${h1_fe1_sock} {
+ # PROXY v2 signature
+ sendhex "0d 0a 0d 0a 00 0d 0a 51 55 49 54 0a"
+ # version + PROXY
+ sendhex "21"
+ # TCP4
+ sendhex "11"
+ # length of the address (12) + length of the TLV (8)
+ sendhex "00 14"
+ # 127.0.0.1 42 127.0.0.1 1337
+ sendhex "7F 00 00 01 7F 00 00 01 00 2A 05 39"
+ # PP2_TYPE_AUTHORITY + length of the value + "12345"
+ sendhex "02 00 05 31 32 33 34 35"
+
+ txreq -url "/"
+ rxresp
+ expect resp.http.echo == "3132333435"
+} -run
+
+haproxy h2 -conf {
+ defaults
+ mode http
+ timeout connect 1s
+ timeout client 1s
+ timeout server 1s
+
+ frontend a
+ bind "fd@${fe1}" accept-proxy
+ http-after-response set-header echo %[fc_pp_authority,hex]
+ http-request return status 200
+} -start
+
+# Validate that a TLV after the end of the PROXYv2 header is ignored
+client c2 -connect ${h2_fe1_sock} {
+ # PROXY v2 signature
+ sendhex "0d 0a 0d 0a 00 0d 0a 51 55 49 54 0a"
+ # version + PROXY
+ sendhex "21"
+ # TCP4
+ sendhex "11"
+ # length of the address (12) + length of the TLV (8)
+ sendhex "00 14"
+ # 127.0.0.1 42 127.0.0.1 1337
+ sendhex "7F 00 00 01 7F 00 00 01 00 2A 05 39"
+ # PP2_TYPE_AUTHORITY + length of the value + "12345"
+ sendhex "02 00 05 31 32 33 34 35"
+ # after the end of the PROXYv2 header: PP2_TYPE_AUTHORITY + length of the value + "54321"
+ sendhex "02 00 05 35 34 33 32 31"
+
+ txreq -url "/"
+ rxresp
+ expect resp.http.echo == "3132333435"
+} -run
+
+haproxy h3 -conf {
+ defaults
+ mode http
+ timeout connect 1s
+ timeout client 1s
+ timeout server 1s
+
+ frontend a
+ bind "fd@${fe1}" accept-proxy
+ http-after-response set-header echo %[fc_pp_authority,hex]
+ http-request return status 200
+} -start
+
+# Validate that a TLV length exceeding the PROXYv2 length fails
+client c3 -connect ${h3_fe1_sock} {
+ # PROXY v2 signature
+ sendhex "0d 0a 0d 0a 00 0d 0a 51 55 49 54 0a"
+ # version + PROXY
+ sendhex "21"
+ # TCP4
+ sendhex "11"
+ # length of the address (12) + too small length of the TLV (8)
+ sendhex "00 14"
+ # 127.0.0.1 42 127.0.0.1 1337
+ sendhex "7F 00 00 01 7F 00 00 01 00 2A 05 39"
+ # PP2_TYPE_AUTHORITY + length of the value + "1234512345"
+ sendhex "02 00 0A 31 32 33 34 35 31 32 33 34 35"
+
+ txreq -url "/"
+ expect_close
+} -run
+
+haproxy h4 -conf {
+ defaults
+ mode http
+ timeout connect 1s
+ timeout client 1s
+ timeout server 1s
+
+ frontend a
+ bind "fd@${fe1}" accept-proxy
+ http-after-response set-header echo %[fc_pp_authority,hex]
+ http-request return status 200
+} -start
+
+# Validate that TLVs not ending with the PROXYv2 header fail
+client c4 -connect ${h4_fe1_sock} {
+ # PROXY v2 signature
+ sendhex "0d 0a 0d 0a 00 0d 0a 51 55 49 54 0a"
+ # version + PROXY
+ sendhex "21"
+ # TCP4
+ sendhex "11"
+ # length of the address (12) + too big length of the TLV (8)
+ sendhex "00 14"
+ # 127.0.0.1 42 127.0.0.1 1337
+ sendhex "7F 00 00 01 7F 00 00 01 00 2A 05 39"
+ # PP2_TYPE_AUTHORITY + length of the value + "1234"
+ sendhex "02 00 04 31 32 33 34"
+
+ txreq -url "/"
+ expect_close
+} -run
diff --git a/src/connection.c b/src/connection.c
index a6e2b34..1ea8e9f 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -490,7 +490,7 @@
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;
@@ -668,7 +668,8 @@
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) {
@@ -686,7 +687,6 @@
((struct sockaddr_in *)conn->dst)->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)
@@ -700,51 +700,74 @@
((struct sockaddr_in6 *)conn->dst)->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
- case PP2_TYPE_AUTHORITY: {
- if (tlv_len > PP2_AUTHORITY_MAX)
- goto bad_header;
- conn->proxy_authority = pool_alloc(pool_head_authority);
- if (conn->proxy_authority == NULL)
- goto fail;
- memcpy(conn->proxy_authority, (const char *)tlv_packet->value, tlv_len);
- conn->proxy_authority_len = tlv_len;
- break;
- }
- default:
- break;
- }
+ case PP2_TYPE_AUTHORITY: {
+ if (tlv_len > PP2_AUTHORITY_MAX)
+ goto bad_header;
+ conn->proxy_authority = pool_alloc(pool_head_authority);
+ if (conn->proxy_authority == NULL)
+ goto fail;
+ memcpy(conn->proxy_authority, (const char *)tlv_packet->value, tlv_len);
+ conn->proxy_authority_len = tlv_len;
+ 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 */
@@ -754,7 +777,7 @@
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: