diff options
Diffstat (limited to 'sys/netinet/ip_reass.c')
| -rw-r--r-- | sys/netinet/ip_reass.c | 654 |
1 files changed, 654 insertions, 0 deletions
diff --git a/sys/netinet/ip_reass.c b/sys/netinet/ip_reass.c new file mode 100644 index 0000000..a7c5d38 --- /dev/null +++ b/sys/netinet/ip_reass.c @@ -0,0 +1,654 @@ +/*- + * Copyright (c) 2015 Gleb Smirnoff <glebius@FreeBSD.org> + * Copyright (c) 2015 Adrian Chadd <adrian@FreeBSD.org> + * 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. + * 4. 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 <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_rss.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/eventhandler.h> +#include <sys/mbuf.h> +#include <sys/malloc.h> +#include <sys/lock.h> +#include <sys/mutex.h> +#include <sys/sysctl.h> + +#include <net/rss_config.h> +#include <net/vnet.h> + +#include <netinet/in.h> +#include <netinet/ip.h> +#include <netinet/ip_var.h> +#include <netinet/in_rss.h> +#ifdef MAC +#include <security/mac/mac_framework.h> +#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) +#define IPREASS_HASH(x,y) \ + (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK) + +struct ipqbucket { + TAILQ_HEAD(ipqhead, ipq) head; + struct mtx lock; +}; + +static VNET_DEFINE(struct ipqbucket, ipq[IPREASS_NHASH]); +#define V_ipq VNET(ipq) + +#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; + u_short 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 = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id); + 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_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); +} |
