BUG/MAJOR: connection: fix TLV offset calculation for proxy protocol v2 parsing

Until now, the code assumed that it can get the offset to the first TLV
header just by subtracting the length of the TLV part from the length of
the complete buffer. However, if the buffer contains actual data after
the header, this computation is flawed and leads to haproxy trying to
parse TLV headers from the proxied data.

This change fixes this by making sure that the offset to the first TLV
header is calculated based from the start of the buffer -- simply by
adding the size of the proxy protocol v2 header plus the address
family-dependent size of the address information block.

diff --git a/src/connection.c b/src/connection.c
index 21fd8fe..6eab5e1 100644 (file)
--- a/src/connection.c
+++ b/src/connection.c
@@ -340,6 +340,7 @@ int conn_recv_proxy(struct connection *conn, int flag)
        struct proxy_hdr_v2 *hdr_v2;
        const char v2sig[] = PP2_SIGNATURE;
        int tlv_length = 0;
+       int tlv_offset = 0;
 
        /* we might have been called just after an asynchronous shutr */
        if (conn->flags & CO_FL_SOCK_RD_SH)
@@ -529,6 +530,7 @@ int conn_recv_proxy(struct connection *conn, int flag)
                        ((struct sockaddr_in *)&conn->addr.to)->sin_addr.s_addr = hdr_v2->addr.ip4.dst_addr;
                        ((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 */
@@ -542,14 +544,13 @@ int conn_recv_proxy(struct connection *conn, int flag)
                        memcpy(&((struct sockaddr_in6 *)&conn->addr.to)->sin6_addr, hdr_v2->addr.ip6.dst_addr, 16);
                        ((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) {
-                       int tlv_offset = trash.len - tlv_length;
-
                        while (tlv_offset + TLV_HEADER_SIZE <= trash.len) {
                                const struct tlv *tlv_packet = (struct tlv *) &trash.str[tlv_offset];
                                const int tlv_len = get_tlv_length(tlv_packet);