IP6: Turned on verbose logging for fragment handling code

[kibab]

Summary

Implement behavior suggested by RFC5722: drop the fragment queue
entirely if the system receives a duplicate fragment

Test Plan

Send a fragmented packet to the system, then send one of the fragments
once again. One can use frag6 tests from the OpenBSD regression suite.

[kibab]

I have added the wrong revision to the review!

This is the correct one, I couldn't edit the patch itself :-(

• a/sys/netinet6/frag6.c

+++ b/sys/netinet6/frag6.c
@@ -63,7 +63,7 @@ static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
static void frag6_deq(struct ip6asfrag *);
static void frag6_insque(struct ip6q *, struct ip6q *);
static void frag6_remque(struct ip6q *);
-static void frag6_freef(struct ip6q *);
+static void frag6_freef(struct ip6q *, int);

static struct mtx ip6qlock;
/*
@@ -459,6 +459,7 @@ frag6_input(struct mbuf **mp, int *offp, int proto)

			    i, ip6_sprintf(ip6buf, &q6->ip6q_src));

#endif

			free(ip6af, M_FTABLE);

+ frag6_freef(q6, 0);

			goto dropfrag;
		}
	}

@@ -471,6 +472,7 @@ frag6_input(struct mbuf **mp, int *offp, int proto)

			    i, ip6_sprintf(ip6buf, &q6->ip6q_src));

#endif

			free(ip6af, M_FTABLE);

+ frag6_freef(q6, 0);

			goto dropfrag;
		}
	}

@@ -603,7 +605,7 @@ insert:

• associated datagrams. */ void

-frag6_freef(struct ip6q *q6)
+frag6_freef(struct ip6q *q6, int sendicmp)
{

	struct ip6asfrag *af6, *down6;

@@ -620,7 +622,7 @@ frag6_freef(struct ip6q *q6)

• • Return ICMP time exceeded error for the 1st fragment.
  • Just free other fragments. */
• if (af6->ip6af_off == 0) {

+ if (af6->ip6af_off == 0 && sendicmp == 1) {

			struct ip6_hdr *ip6;

			/* adjust pointer */

@@ -719,7 +721,7 @@ frag6_slowtimo(void)

				if (q6->ip6q_prev->ip6q_ttl == 0) {
					IP6STAT_INC(ip6s_fragtimeout);
					/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */

• frag6_freef(q6->ip6q_prev);

+ frag6_freef(q6->ip6q_prev, 1);

				}
			}
		/*

@@ -731,7 +733,7 @@ frag6_slowtimo(void)

		    V_ip6q.ip6q_prev) {
			IP6STAT_INC(ip6s_fragoverflow);
			/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */

• frag6_freef(V_ip6q.ip6q_prev);

+ frag6_freef(V_ip6q.ip6q_prev, 1);

		}
		CURVNET_RESTORE();
	}

@@ -757,7 +759,7 @@ frag6_drain(void)

		while (V_ip6q.ip6q_next != &V_ip6q) {
			IP6STAT_INC(ip6s_fragdropped);
			/* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */

• frag6_freef(V_ip6q.ip6q_next);

+ frag6_freef(V_ip6q.ip6q_next, 1);

		}
		CURVNET_RESTORE();
	}

[ae]

I think you need to adjust some comments in frag6_input().

[bz]

I somehow would expect a comment to be updated somewhere referencing RFC5722?

Appart from that no objections though I have only skimmed through and not properly reviewed this.

[kibab]

This is an ancient sh*t and nobody cares.