Implement an ipfw action to reassemble ip packets: reass.

svn path=/head/; revision=190633

sbin/ipfw/ipfw.8

@@ -866,6 +866,13 @@ in any subsequent forwarding decisions.
 Initially this is limited to the values 0 through 15, see
 .Xr setfib 8 .
 Processing continues at the next rule.
+.It Cm reass
+Queue and reassemble ip fragments.
+If the packet is not fragmented, counters are updated and processing continues with the next rule.
+If the packet is the last logical fragment, the packet is reassembled and, if
+.Va net.inet.ip.fw.one_pass
+is set to 0, processing continues with the next rule, else packet is allowed to pass and search terminates.
+If the packet is a fragment in the middle, it is consumed and processing stops immediately.
 .El
 .Ss RULE BODY
 The body of a rule contains zero or more patterns (such as

sbin/ipfw/ipfw2.c

@@ -211,6 +211,7 @@ static struct _s_x rule_actions[] = {
 	{ "check-state",	TOK_CHECKSTATE },
 	{ "//",			TOK_COMMENT },
 	{ "nat",                TOK_NAT },
+	{ "reass",		TOK_REASS },
 	{ "setfib",		TOK_SETFIB },
 	{ NULL, 0 }	/* terminator */
 };
@@ -1089,6 +1090,10 @@ show_ipfw(struct ip_fw *rule, int pcwidth, int bcwidth)
 		case O_SETFIB:
 			PRINT_UINT_ARG("setfib ", cmd->arg1);
  			break;
+
+		case O_REASS:
+			printf("reass");
+			break;
 			
 		default:
 			printf("** unrecognized action %d len %d ",
@@ -2781,6 +2786,10 @@ ipfw_add(int ac, char *av[])
  		ac--; av++;
  		break;
 	    }
+
+	case TOK_REASS:
+		action->opcode = O_REASS;
+		break;
 		
 	default:
 		errx(EX_DATAERR, "invalid action %s\n", av[-1]);

sbin/ipfw/ipfw2.h

@@ -95,6 +95,7 @@ enum tokens {
 	TOK_UNREACH,
 	TOK_CHECKSTATE,
 	TOK_NAT,
+	TOK_REASS,
 
 	TOK_ALTQ,
 	TOK_LOG,

sbin/ipfw/main.c

@@ -54,7 +54,7 @@ help(void)
 "RULE-BODY:	check-state [PARAMS] | ACTION [PARAMS] ADDR [OPTION_LIST]\n"
 "ACTION:	check-state | allow | count | deny | unreach{,6} CODE |\n"
 "               skipto N | {divert|tee} PORT | forward ADDR |\n"
-"               pipe N | queue N | nat N | setfib FIB\n"
+"               pipe N | queue N | nat N | setfib FIB | reass\n"
 "PARAMS: 	[log [logamount LOGLIMIT]] [altq QUEUE_NAME]\n"
 "ADDR:		[ MAC dst src ether_type ] \n"
 "		[ ip from IPADDR [ PORT ] to IPADDR [ PORTLIST ] ]\n"

sys/netinet/ip_fw.h

@@ -139,7 +139,8 @@ enum ipfw_opcodes {		/* arguments (4 byte each)	*/
 	O_FORWARD_IP,		/* fwd sockaddr			*/
 	O_FORWARD_MAC,		/* fwd mac			*/
 	O_NAT,                  /* nope                         */
-
+	O_REASS,                /* none                         */
+	
 	/*
 	 * More opcodes.
 	 */
@@ -574,6 +575,7 @@ enum {
 	IP_FW_NETGRAPH,
 	IP_FW_NGTEE,
 	IP_FW_NAT,
+	IP_FW_REASS,
 };
 
 /* flags for divert mtag */

sys/netinet/ip_fw2.c

@@ -898,6 +898,9 @@ ipfw_log(struct ip_fw *f, u_int hlen, struct ip_fw_args *args,
 		case O_NAT:
 			action = "Nat";
  			break;
+		case O_REASS:
+			action = "Reass";
+			break;
 		default:
 			action = "UNKNOWN";
 			break;
@@ -3375,6 +3378,55 @@ do {									\
 				goto done;
 			}
 
+			case O_REASS: {
+				int ip_off;
+
+				f->pcnt++;
+				f->bcnt += pktlen;
+				ip_off = (args->eh != NULL) ? ntohs(ip->ip_off) : ip->ip_off;
+				if (ip_off & (IP_MF | IP_OFFMASK)) {
+					/* 
+					 * ip_reass() expects len & off in host
+					 * byte order: fix them in case we come
+					 * from layer2.
+					 */
+					if (args->eh != NULL) {
+						ip->ip_len = ntohs(ip->ip_len);
+						ip->ip_off = ntohs(ip->ip_off);
+					}
+
+					m = ip_reass(m);
+					args->m = m;
+					
+					/*
+					 * IP header checksum fixup after 
+					 * reassembly and leave header
+					 * in network byte order.
+					 */
+					if (m != NULL) {
+						int hlen;
+					
+						ip = mtod(m, struct ip *);
+						hlen = ip->ip_hl << 2;
+						/* revert len & off for layer2 pkts */
+						if (args->eh != NULL)
+							ip->ip_len = htons(ip->ip_len);
+						ip->ip_sum = 0;
+						if (hlen == sizeof(struct ip))
+							ip->ip_sum = in_cksum_hdr(ip);
+						else
+							ip->ip_sum = in_cksum(m, hlen);
+						retval = IP_FW_REASS;
+						args->rule = f;
+						goto done;
+					} else {
+						retval = IP_FW_DENY;
+						goto done;
+					}
+				}
+				goto next_rule;
+			}
+
 			default:
 				panic("-- unknown opcode %d\n", cmd->opcode);
 			} /* end of switch() on opcodes */
@@ -4024,6 +4076,7 @@ check_ipfw_struct(struct ip_fw *rule, int size)
 		case O_UNREACH6:
 #endif
 		case O_SKIPTO:
+		case O_REASS:
 check_size:
 			if (cmdlen != F_INSN_SIZE(ipfw_insn))
 				goto bad_size;

sys/netinet/ip_fw_pfil.c

@@ -200,6 +200,9 @@ ipfw_check_in(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir,
 	case IP_FW_NAT:
 		goto again;		/* continue with packet */
 
+	case IP_FW_REASS:
+		goto again;
+
 	default:
 		KASSERT(0, ("%s: unknown retval", __func__));
 	}
@@ -329,6 +332,9 @@ ipfw_check_out(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir,
 	case IP_FW_NAT:
 		goto again;		/* continue with packet */
 		
+	case IP_FW_REASS:
+		goto again;	
+	
 	default:
 		KASSERT(0, ("%s: unknown retval", __func__));
 	}