/*- * Copyright (c) 2015 Gleb Smirnoff * Copyright (c) 2015 Adrian Chadd * Copyright (c) 1982, 1986, 1988, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)ip_input.c 8.2 (Berkeley) 1/4/94 */ #include __FBSDID("$FreeBSD$"); #include "opt_rss.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef MAC #include #endif SYSCTL_DECL(_net_inet_ip); /* * Reassembly headers are stored in hash buckets. */ #define IPREASS_NHASH_LOG2 6 #define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2) #define IPREASS_HMASK (IPREASS_NHASH - 1) struct ipqbucket { TAILQ_HEAD(ipqhead, ipq) head; struct mtx lock; }; static VNET_DEFINE(struct ipqbucket, ipq[IPREASS_NHASH]); #define V_ipq VNET(ipq) static VNET_DEFINE(uint32_t, ipq_hashseed); #define V_ipq_hashseed VNET(ipq_hashseed) #define IPQ_LOCK(i) mtx_lock(&V_ipq[i].lock) #define IPQ_TRYLOCK(i) mtx_trylock(&V_ipq[i].lock) #define IPQ_UNLOCK(i) mtx_unlock(&V_ipq[i].lock) #define IPQ_LOCK_ASSERT(i) mtx_assert(&V_ipq[i].lock, MA_OWNED) void ipreass_init(void); void ipreass_drain(void); void ipreass_slowtimo(void); #ifdef VIMAGE void ipreass_destroy(void); #endif static int sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS); static void ipreass_zone_change(void *); static void ipreass_drain_tomax(void); static void ipq_free(struct ipqhead *, struct ipq *); static struct ipq * ipq_reuse(int); static inline void ipq_timeout(struct ipqhead *head, struct ipq *fp) { IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags); ipq_free(head, fp); } static inline void ipq_drop(struct ipqhead *head, struct ipq *fp) { IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags); ipq_free(head, fp); } static VNET_DEFINE(uma_zone_t, ipq_zone); #define V_ipq_zone VNET(ipq_zone) SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, NULL, 0, sysctl_maxfragpackets, "I", "Maximum number of IPv4 fragment reassembly queue entries"); SYSCTL_UMA_CUR(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_VNET, &VNET_NAME(ipq_zone), "Current number of IPv4 fragment reassembly queue entries"); static VNET_DEFINE(int, noreass); #define V_noreass VNET(noreass) static VNET_DEFINE(int, maxfragsperpacket); #define V_maxfragsperpacket VNET(maxfragsperpacket) SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(maxfragsperpacket), 0, "Maximum number of IPv4 fragments allowed per packet"); /* * Take incoming datagram fragment and try to reassemble it into * whole datagram. If the argument is the first fragment or one * in between the function will return NULL and store the mbuf * in the fragment chain. If the argument is the last fragment * the packet will be reassembled and the pointer to the new * mbuf returned for further processing. Only m_tags attached * to the first packet/fragment are preserved. * The IP header is *NOT* adjusted out of iplen. */ #define M_IP_FRAG M_PROTO9 struct mbuf * ip_reass(struct mbuf *m) { struct ip *ip; struct mbuf *p, *q, *nq, *t; struct ipq *fp; struct ipqhead *head; int i, hlen, next; u_int8_t ecn, ecn0; uint32_t hash; #ifdef RSS uint32_t rss_hash, rss_type; #endif /* * If no reassembling or maxfragsperpacket are 0, * never accept fragments. */ if (V_noreass == 1 || V_maxfragsperpacket == 0) { IPSTAT_INC(ips_fragments); IPSTAT_INC(ips_fragdropped); m_freem(m); return (NULL); } ip = mtod(m, struct ip *); hlen = ip->ip_hl << 2; /* * Adjust ip_len to not reflect header, * convert offset of this to bytes. */ ip->ip_len = htons(ntohs(ip->ip_len) - hlen); if (ip->ip_off & htons(IP_MF)) { /* * Make sure that fragments have a data length * that's a non-zero multiple of 8 bytes. */ if (ip->ip_len == htons(0) || (ntohs(ip->ip_len) & 0x7) != 0) { IPSTAT_INC(ips_toosmall); /* XXX */ IPSTAT_INC(ips_fragdropped); m_freem(m); return (NULL); } m->m_flags |= M_IP_FRAG; } else m->m_flags &= ~M_IP_FRAG; ip->ip_off = htons(ntohs(ip->ip_off) << 3); /* * Attempt reassembly; if it succeeds, proceed. * ip_reass() will return a different mbuf. */ IPSTAT_INC(ips_fragments); m->m_pkthdr.PH_loc.ptr = ip; /* * Presence of header sizes in mbufs * would confuse code below. */ m->m_data += hlen; m->m_len -= hlen; hash = ip->ip_src.s_addr ^ ip->ip_id; hash = jenkins_hash32(&hash, 1, V_ipq_hashseed) & IPREASS_HMASK; head = &V_ipq[hash].head; IPQ_LOCK(hash); /* * Look for queue of fragments * of this datagram. */ TAILQ_FOREACH(fp, head, ipq_list) if (ip->ip_id == fp->ipq_id && ip->ip_src.s_addr == fp->ipq_src.s_addr && ip->ip_dst.s_addr == fp->ipq_dst.s_addr && #ifdef MAC mac_ipq_match(m, fp) && #endif ip->ip_p == fp->ipq_p) break; /* * If first fragment to arrive, create a reassembly queue. */ if (fp == NULL) { fp = uma_zalloc(V_ipq_zone, M_NOWAIT); if (fp == NULL) fp = ipq_reuse(hash); #ifdef MAC if (mac_ipq_init(fp, M_NOWAIT) != 0) { uma_zfree(V_ipq_zone, fp); fp = NULL; goto dropfrag; } mac_ipq_create(m, fp); #endif TAILQ_INSERT_HEAD(head, fp, ipq_list); fp->ipq_nfrags = 1; fp->ipq_ttl = IPFRAGTTL; fp->ipq_p = ip->ip_p; fp->ipq_id = ip->ip_id; fp->ipq_src = ip->ip_src; fp->ipq_dst = ip->ip_dst; fp->ipq_frags = m; m->m_nextpkt = NULL; goto done; } else { fp->ipq_nfrags++; #ifdef MAC mac_ipq_update(m, fp); #endif } #define GETIP(m) ((struct ip*)((m)->m_pkthdr.PH_loc.ptr)) /* * Handle ECN by comparing this segment with the first one; * if CE is set, do not lose CE. * drop if CE and not-ECT are mixed for the same packet. */ ecn = ip->ip_tos & IPTOS_ECN_MASK; ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK; if (ecn == IPTOS_ECN_CE) { if (ecn0 == IPTOS_ECN_NOTECT) goto dropfrag; if (ecn0 != IPTOS_ECN_CE) GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE; } if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) goto dropfrag; /* * Find a segment which begins after this one does. */ for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off)) break; /* * If there is a preceding segment, it may provide some of * our data already. If so, drop the data from the incoming * segment. If it provides all of our data, drop us, otherwise * stick new segment in the proper place. * * If some of the data is dropped from the preceding * segment, then it's checksum is invalidated. */ if (p) { i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) - ntohs(ip->ip_off); if (i > 0) { if (i >= ntohs(ip->ip_len)) goto dropfrag; m_adj(m, i); m->m_pkthdr.csum_flags = 0; ip->ip_off = htons(ntohs(ip->ip_off) + i); ip->ip_len = htons(ntohs(ip->ip_len) - i); } m->m_nextpkt = p->m_nextpkt; p->m_nextpkt = m; } else { m->m_nextpkt = fp->ipq_frags; fp->ipq_frags = m; } /* * While we overlap succeeding segments trim them or, * if they are completely covered, dequeue them. */ for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) > ntohs(GETIP(q)->ip_off); q = nq) { i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) - ntohs(GETIP(q)->ip_off); if (i < ntohs(GETIP(q)->ip_len)) { GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i); GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i); m_adj(q, i); q->m_pkthdr.csum_flags = 0; break; } nq = q->m_nextpkt; m->m_nextpkt = nq; IPSTAT_INC(ips_fragdropped); fp->ipq_nfrags--; m_freem(q); } /* * Check for complete reassembly and perform frag per packet * limiting. * * Frag limiting is performed here so that the nth frag has * a chance to complete the packet before we drop the packet. * As a result, n+1 frags are actually allowed per packet, but * only n will ever be stored. (n = maxfragsperpacket.) * */ next = 0; for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) { if (ntohs(GETIP(q)->ip_off) != next) { if (fp->ipq_nfrags > V_maxfragsperpacket) ipq_drop(head, fp); goto done; } next += ntohs(GETIP(q)->ip_len); } /* Make sure the last packet didn't have the IP_MF flag */ if (p->m_flags & M_IP_FRAG) { if (fp->ipq_nfrags > V_maxfragsperpacket) ipq_drop(head, fp); goto done; } /* * Reassembly is complete. Make sure the packet is a sane size. */ q = fp->ipq_frags; ip = GETIP(q); if (next + (ip->ip_hl << 2) > IP_MAXPACKET) { IPSTAT_INC(ips_toolong); ipq_drop(head, fp); goto done; } /* * Concatenate fragments. */ m = q; t = m->m_next; m->m_next = NULL; m_cat(m, t); nq = q->m_nextpkt; q->m_nextpkt = NULL; for (q = nq; q != NULL; q = nq) { nq = q->m_nextpkt; q->m_nextpkt = NULL; m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags; m->m_pkthdr.csum_data += q->m_pkthdr.csum_data; m_cat(m, q); } /* * In order to do checksumming faster we do 'end-around carry' here * (and not in for{} loop), though it implies we are not going to * reassemble more than 64k fragments. */ while (m->m_pkthdr.csum_data & 0xffff0000) m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + (m->m_pkthdr.csum_data >> 16); #ifdef MAC mac_ipq_reassemble(fp, m); mac_ipq_destroy(fp); #endif /* * Create header for new ip packet by modifying header of first * packet; dequeue and discard fragment reassembly header. * Make header visible. */ ip->ip_len = htons((ip->ip_hl << 2) + next); ip->ip_src = fp->ipq_src; ip->ip_dst = fp->ipq_dst; TAILQ_REMOVE(head, fp, ipq_list); uma_zfree(V_ipq_zone, fp); m->m_len += (ip->ip_hl << 2); m->m_data -= (ip->ip_hl << 2); /* some debugging cruft by sklower, below, will go away soon */ if (m->m_flags & M_PKTHDR) /* XXX this should be done elsewhere */ m_fixhdr(m); IPSTAT_INC(ips_reassembled); IPQ_UNLOCK(hash); #ifdef RSS /* * Query the RSS layer for the flowid / flowtype for the * mbuf payload. * * For now, just assume we have to calculate a new one. * Later on we should check to see if the assigned flowid matches * what RSS wants for the given IP protocol and if so, just keep it. * * We then queue into the relevant netisr so it can be dispatched * to the correct CPU. * * Note - this may return 1, which means the flowid in the mbuf * is correct for the configured RSS hash types and can be used. */ if (rss_mbuf_software_hash_v4(m, 0, &rss_hash, &rss_type) == 0) { m->m_pkthdr.flowid = rss_hash; M_HASHTYPE_SET(m, rss_type); } /* * Queue/dispatch for reprocessing. * * Note: this is much slower than just handling the frame in the * current receive context. It's likely worth investigating * why this is. */ netisr_dispatch(NETISR_IP_DIRECT, m); return (NULL); #endif /* Handle in-line */ return (m); dropfrag: IPSTAT_INC(ips_fragdropped); if (fp != NULL) fp->ipq_nfrags--; m_freem(m); done: IPQ_UNLOCK(hash); return (NULL); #undef GETIP } /* * Initialize IP reassembly structures. */ void ipreass_init(void) { for (int i = 0; i < IPREASS_NHASH; i++) { TAILQ_INIT(&V_ipq[i].head); mtx_init(&V_ipq[i].lock, "IP reassembly", NULL, MTX_DEF | MTX_DUPOK); } V_ipq_hashseed = arc4random(); V_maxfragsperpacket = 16; V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); uma_zone_set_max(V_ipq_zone, nmbclusters / 32); if (IS_DEFAULT_VNET(curvnet)) EVENTHANDLER_REGISTER(nmbclusters_change, ipreass_zone_change, NULL, EVENTHANDLER_PRI_ANY); } /* * If a timer expires on a reassembly queue, discard it. */ void ipreass_slowtimo(void) { struct ipq *fp, *tmp; for (int i = 0; i < IPREASS_NHASH; i++) { IPQ_LOCK(i); TAILQ_FOREACH_SAFE(fp, &V_ipq[i].head, ipq_list, tmp) if (--fp->ipq_ttl == 0) ipq_timeout(&V_ipq[i].head, fp); IPQ_UNLOCK(i); } } /* * Drain off all datagram fragments. */ void ipreass_drain(void) { for (int i = 0; i < IPREASS_NHASH; i++) { IPQ_LOCK(i); while(!TAILQ_EMPTY(&V_ipq[i].head)) ipq_drop(&V_ipq[i].head, TAILQ_FIRST(&V_ipq[i].head)); IPQ_UNLOCK(i); } } #ifdef VIMAGE /* * Destroy IP reassembly structures. */ void ipreass_destroy(void) { ipreass_drain(); uma_zdestroy(V_ipq_zone); for (int i = 0; i < IPREASS_NHASH; i++) mtx_destroy(&V_ipq[i].lock); } #endif /* * After maxnipq has been updated, propagate the change to UMA. The UMA zone * max has slightly different semantics than the sysctl, for historical * reasons. */ static void ipreass_drain_tomax(void) { int target; /* * If we are over the maximum number of fragments, * drain off enough to get down to the new limit, * stripping off last elements on queues. Every * run we strip the oldest element from each bucket. */ target = uma_zone_get_max(V_ipq_zone); while (uma_zone_get_cur(V_ipq_zone) > target) { struct ipq *fp; for (int i = 0; i < IPREASS_NHASH; i++) { IPQ_LOCK(i); fp = TAILQ_LAST(&V_ipq[i].head, ipqhead); if (fp != NULL) ipq_timeout(&V_ipq[i].head, fp); IPQ_UNLOCK(i); } } } static void ipreass_zone_change(void *tag) { uma_zone_set_max(V_ipq_zone, nmbclusters / 32); ipreass_drain_tomax(); } /* * Change the limit on the UMA zone, or disable the fragment allocation * at all. Since 0 and -1 is a special values here, we need our own handler, * instead of sysctl_handle_uma_zone_max(). */ static int sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS) { int error, max; if (V_noreass == 0) { max = uma_zone_get_max(V_ipq_zone); if (max == 0) max = -1; } else max = 0; error = sysctl_handle_int(oidp, &max, 0, req); if (error || !req->newptr) return (error); if (max > 0) { /* * XXXRW: Might be a good idea to sanity check the argument * and place an extreme upper bound. */ max = uma_zone_set_max(V_ipq_zone, max); ipreass_drain_tomax(); V_noreass = 0; } else if (max == 0) { V_noreass = 1; ipreass_drain(); } else if (max == -1) { V_noreass = 0; uma_zone_set_max(V_ipq_zone, 0); } else return (EINVAL); return (0); } /* * Seek for old fragment queue header that can be reused. Try to * reuse a header from currently locked hash bucket. */ static struct ipq * ipq_reuse(int start) { struct ipq *fp; int i; IPQ_LOCK_ASSERT(start); for (i = start;; i++) { if (i == IPREASS_NHASH) i = 0; if (i != start && IPQ_TRYLOCK(i) == 0) continue; fp = TAILQ_LAST(&V_ipq[i].head, ipqhead); if (fp) { struct mbuf *m; IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags); while (fp->ipq_frags) { m = fp->ipq_frags; fp->ipq_frags = m->m_nextpkt; m_freem(m); } TAILQ_REMOVE(&V_ipq[i].head, fp, ipq_list); if (i != start) IPQ_UNLOCK(i); IPQ_LOCK_ASSERT(start); return (fp); } if (i != start) IPQ_UNLOCK(i); } } /* * Free a fragment reassembly header and all associated datagrams. */ static void ipq_free(struct ipqhead *fhp, struct ipq *fp) { struct mbuf *q; while (fp->ipq_frags) { q = fp->ipq_frags; fp->ipq_frags = q->m_nextpkt; m_freem(q); } TAILQ_REMOVE(fhp, fp, ipq_list); uma_zfree(V_ipq_zone, fp); }