From: Matt Corallo <git@bluematt.me>
Date: Sun, 4 Apr 2021 20:46:04 +0000 (-0400)
Subject: Track ports valid directly - as LLVM will | pointers which BPF wont allow
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=a8be3b609743627f58a464d7b75217a778eb4fa9;p=flowspec-xdp

Track ports valid directly - as LLVM will | pointers which BPF wont allow
---

diff --git a/genrules.py b/genrules.py
index edef617..4468c1e 100755
--- a/genrules.py
+++ b/genrules.py
@@ -232,10 +232,10 @@ def dscp_to_rule(proto, rules):
 def port_to_rule(ty, rules):
     if ty == "port" :
         ast = parse_ast(rules, parse_numbers_expr)
-        return "if (tcp == NULL && udp == NULL) break;\nif (!( " + ast.write("sport", "dport") + " )) break;"
+        return "if (!ports_valid) break;\nif (!( " + ast.write("sport", "dport") + " )) break;"
 
     ast = parse_ast(rules, parse_numbers_expr)
-    return "if (tcp == NULL && udp == NULL) break;\nif (!( " + ast.write(ty) + " )) break;"
+    return "if (!ports_valid) break;\nif (!( " + ast.write(ty) + " )) break;"
 
 def tcp_flags_to_rule(rules):
     ast = parse_ast(rules, parse_bit_expr)
diff --git a/xdp.c b/xdp.c
index 01feac6..4e4d6c6 100644
--- a/xdp.c
+++ b/xdp.c
@@ -204,7 +204,7 @@ int xdp_drop_prog(struct xdp_md *ctx)
 
 	const void *l4hdr = NULL;
 	const struct tcphdr *tcp = NULL;
-	const struct udphdr *udp = NULL;
+	uint8_t ports_valid = 0;
 	uint16_t sport, dport; // Host Endian! Only valid with tcp || udp
 
 #ifdef NEED_V4_PARSE
@@ -227,11 +227,13 @@ int xdp_drop_prog(struct xdp_md *ctx)
 				tcp = (struct tcphdr*) l4hdr;
 				sport = BE16(tcp->source);
 				dport = BE16(tcp->dest);
+				ports_valid = 1;
 			} else if (ip->protocol == IP_PROTO_UDP) {
 				CHECK_LEN(l4hdr, udphdr);
-				udp = (struct udphdr*) l4hdr;
+				const struct udphdr *udp = (struct udphdr*) l4hdr;
 				sport = BE16(udp->source);
 				dport = BE16(udp->dest);
+				ports_valid = 1;
 			} else if (ip->protocol == IP_PROTO_ICMP) {
 				CHECK_LEN(l4hdr, icmphdr);
 				icmp = (struct icmphdr*) l4hdr;
@@ -272,11 +274,13 @@ int xdp_drop_prog(struct xdp_md *ctx)
 				tcp = (struct tcphdr*) l4hdr;
 				sport = BE16(tcp->source);
 				dport = BE16(tcp->dest);
+				ports_valid = 1;
 			} else if (v6nexthdr == IP_PROTO_UDP) {
 				CHECK_LEN(l4hdr, udphdr);
-				udp = (struct udphdr*) l4hdr;
+				const struct udphdr *udp = (struct udphdr*) l4hdr;
 				sport = BE16(udp->source);
 				dport = BE16(udp->dest);
+				ports_valid = 1;
 			} else if (v6nexthdr == IP6_PROTO_ICMPV6) {
 				CHECK_LEN(l4hdr, icmp6hdr);
 				icmpv6 = (struct icmp6hdr*) l4hdr;