Date: Wed, 12 Nov 2003 23:53:26 +0100 From: Jesper Skriver <jesper@FreeBSD.org> To: Andre Oppermann <oppermann@pipeline.ch> Cc: sam@errno.com Subject: Re: tcp hostcache and ip fastforward for review Message-ID: <20031112225326.GI41949@FreeBSD.org> In-Reply-To: <3FAE68FB.64D262FF@pipeline.ch> References: <3FAE68FB.64D262FF@pipeline.ch>
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On Sun, Nov 09, 2003 at 05:19:07PM +0100, Andre Oppermann wrote:
> Hello all,
>
> this patch contains three things (to be separated for committing):
>
> tcp_hostcache
>
> - removes protocol cloning from routing table (IPv4+6)
> - removes rtentry pointer from inpcb and in6pcb
> - removes ip route cache in ip_input.c (locking much easier)
> - removes most (tcp specific) metrics from rtentry metrics
> - adds a hostcache table which carries the metrics for tcp
> - works transparently for IPv4 and IPv6
> - is designed for concurrent access in SMP environments
> - significant reduction of routing table size (no cloning anymore)
> - eases many routing table locking situations in ip/tcp code
>
> ip_fastforward
>
> - removes ip_flow forwarding code
> - adds full direct process-to-completion IPv4 forwarding code
> - handles ip fragmentation incl. hw support (ip_flow did not)
> - supports ipfw and ipfilter (ip_flow did not)
> - supports divert and ipfw fwd (ip_flow did not)
> - drops anything it can't handle back to normal ip_input
I have a few comments to this code, see inline, look for #jesper
Apart from that it looks good.
/Jesper
> +int
> +ip_fastforward(struct mbuf *m)
> +{
> + struct ip *ip;
> + struct mbuf *m0 = NULL;
> +#ifdef IPDIVERT
> + struct ip *tip;
> + struct mbuf *teem = NULL;
> +#endif
> + struct mbuf *tag = NULL;
> + struct route ro;
> + struct sockaddr_in *dst = NULL;
> + struct in_ifaddr *ia = NULL;
> + struct ifaddr *ifa = NULL;
> + struct ifnet *ifp = NULL;
> + struct ip_fw_args args;
> + in_addr_t odest, dest;
> + u_short sum;
> + int hlen;
> + int error = 0;
> + int ipfw;
> +
> + /*
> + * Are we active and forwarding packets?
> + */
> + if (!ipfastforward_active || !ipforwarding)
> + return 0;
> +
> + /*
> + * If there is any MT_TAG we fall back to ip_input because we can't
> + * handle TAGs here.
> + */
> + if (m && m->m_type == MT_TAG)
> + return 0;
> +
> + M_ASSERTVALID(m);
> + M_ASSERTPKTHDR(m);
> +
[...]
> +
> + /*
> + * Only unicast IP, not from loopback, no L2 or IP broadcast,
> + * no multicast, no INADDR_ANY
> + */
> + if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) ||
> + (ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST) ||
#jesper
You will never see packets with a multicast source address.
> + (ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST) ||
> + (IN_MULTICAST(ntohl(ip->ip_src.s_addr))) ||
> + (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) ||
> + (ip->ip_dst.s_addr == INADDR_ANY) )
> + goto fallback;
> +
> + /*
> + * Is it for a local address on this host?
> + */
> + LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
> + if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) {
> + goto fallback;
> + }
> + }
> +
> + /*
> + * Or is it for a local IP broadcast address on this host?
> + */
> + if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
> + TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
> + if (ifa->ifa_addr->sa_family != AF_INET)
> + continue;
> + ia = ifatoia(ifa);
> + if (ia->ia_netbroadcast.s_addr == ip->ip_dst.s_addr)
> + goto fallback;
> + if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
> + ip->ip_dst.s_addr)
> + goto fallback;
> + continue;
> +fallback:
> + /* drop the packet back to netisr */
> + ip->ip_len = htons(ip->ip_len);
> + ip->ip_off = htons(ip->ip_off);
> + return 0;
> + }
> + }
> + ipstat.ips_total++;
#jesper
If we stored special "for us" /32 routes in the routing table for
addresses configured on this host, we could avoid the above 2 loops,
which can quite expensive.
These special routes will simply mean that the packet is for us, and
needs to given to ip_input
> + /**
> + ** Third: incoming packet firewall processing
> + **/
> +
> + odest = dest = ip->ip_dst.s_addr;
#jesper
You could save a few cycles by doing
#ifdef PFIL_HOOKS
odest = ip->ip_dst.s_addr;
/*
* Run through list of ipfilter hooks for input packets
*/
if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN) ||
m == NULL)
return 1;
M_ASSERTVALID(m);
M_ASSERTPKTHDR(m);
ip = mtod(m, struct ip *); /* if m changed during fw processing */
dest = ip->ip_dst.s_addr;
#else
odest = dest = ip->ip_dst.s_addr;
#endif
Thus avoiding writing to dest twice.
> +#ifdef PFIL_HOOKS
> + /*
> + * Run through list of ipfilter hooks for input packets
> + */
> + if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN) ||
> + m == NULL)
> + return 1;
> +
> + M_ASSERTVALID(m);
> + M_ASSERTPKTHDR(m);
> +
> + ip = mtod(m, struct ip *); /* if m changed during fw processing */
> + dest = ip->ip_dst.s_addr;
> +#endif
> +
> + /*
> + * Run through ipfw for input packets
> + */
> + if (fw_enable && IPFW_LOADED) {
> + bzero(&args, sizeof(args));
> + args.m = m;
> + ipfw = 0;
> +
> + ipfw = ip_fw_chk_ptr(&args);
> + m = args.m;
> +
> + M_ASSERTVALID(m);
> + M_ASSERTPKTHDR(m);
> +
> + /*
> + * Packet denied, drop it
> + */
> + if ( (ipfw & IP_FW_PORT_DENY_FLAG) || m == NULL) {
> + if (m)
> + m_freem(m);
> + return 1;
> + }
> + /*
> + * Send packet to the appropriate pipe
> + */
> + if (DUMMYNET_LOADED && (ipfw & IP_FW_PORT_DYNT_FLAG) != 0) {
#jesper
Whitespace bug, spaces instead of tabs
> + ip_dn_io_ptr(m, ipfw & 0xffff, DN_TO_IP_IN, &args);
> + return 1;
> + }
> +#ifdef IPDIVERT
> + /*
> + * Divert packet
> + */
> + if (ipfw != 0 && (ipfw & IP_FW_PORT_DYNT_FLAG) == 0) {
> + /*
> + * See if this is a fragment
> + */
> + if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
> + MGETHDR(tag, M_DONTWAIT, MT_TAG);
> + if (tag == NULL) {
> + m_freem(m);
> + return 1;
> + }
> + tag->m_flags = PACKET_TAG_DIVERT;
> + tag->m_data = (caddr_t)(u_long)args.divert_rule;
> + tag->m_next = m;
> + m = tag;
> + tag = NULL;
> +
> + goto droptoours;
#jesper
Whitespace bug, spaces instead of tabs
> + }
> + /*
> + * Tee packet
> + */
> + if ((ipfw & IP_FW_PORT_TEE_FLAG) != 0)
> + teem = m_dup(m, M_DONTWAIT);
> + else
> + teem = m;
> + if (teem == NULL)
> + goto passin;
> +
> + M_ASSERTVALID(teem);
> + M_ASSERTPKTHDR(teem);
> +
> + /*
> + * Delayed checksums are not compatible
> + */
> + if (teem->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
> + in_delayed_cksum(teem);
> + teem->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
> + }
> + /*
> + * Restore packet header fields to original values
> + */
> + tip = mtod(teem, struct ip *);
> + tip->ip_len = htons(tip->ip_len);
> + tip->ip_off = htons(tip->ip_off);
> + /*
> + * Deliver packet to divert input routine
> + */
> + divert_packet(teem, 0, ipfw & 0xffff, args.divert_rule);
> + /*
> + * If this was not tee, we are done
> + */
> + if ((ipfw & IP_FW_PORT_TEE_FLAG) == 0)
> + return 1;
> + /* Continue if it was tee */
> + goto passin;
> + }
> +#endif
> + if (ipfw == 0 && args.next_hop != NULL) {
> + dest = args.next_hop->sin_addr.s_addr;
> + goto passin;
> + }
> + /*
> + * Let through or not?
> + */
> + if (ipfw != 0) {
> + m_freem(m);
> + return 1;
> + }
> + }
> +passin:
> + ip = mtod(m, struct ip *); /* if m changed during fw processing */
> +
> + /*
> + * Destination address changed?
> + */
> + if (odest != dest) {
> + /*
> + * Is it now for a local address on this host?
> + */
> + LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
> + if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
> + goto forwardlocal;
> + }
#jesper
Same comment as above - and do we really want to see if the original
destination address was ours if we're doing NAT ?
> + /*
> + * Go on with new destination address
> + */
> + }
> +
> + M_ASSERTVALID(m);
> + M_ASSERTPKTHDR(m);
> +
> + /**
> + ** Forth: decrement TTL and look up route
> + **/
> +
> + /*
> + * Check TTL
> + */
> +#ifdef IPSTEALTH
> + if (!ipstealth) {
> +#endif
> + if (ip->ip_ttl <= IPTTLDEC) {
> + icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, NULL, NULL);
> + return 1;
> + }
> +
> + /*
> + * Decrement the TTL and incrementally change the checksum.
> + * Don't bother doing this with hw checksum offloading.
> + */
> + ip->ip_ttl -= IPTTLDEC;
> + if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
> + ip->ip_sum -= ~htons(IPTTLDEC << 8);
> + else
> + ip->ip_sum += htons(IPTTLDEC << 8);
> +#ifdef IPSTEALTH
> + }
> +#endif
> +
> + /*
> + * Find route to destination.
> + */
> + bzero(&ro, sizeof(ro));
> + dst = (struct sockaddr_in *)&ro.ro_dst;
> + dst->sin_family = AF_INET;
> + dst->sin_len = sizeof(*dst);
> + dst->sin_addr.s_addr = dest;
> + rtalloc(&ro);
> +
> + /*
> + * Route there and interface still up?
> + */
> + if ((ro.ro_rt) &&
> + (ro.ro_rt->rt_flags & RTF_UP) &&
> + (ro.ro_rt->rt_ifp->if_flags & IFF_UP)) {
> + ia = ifatoia(ro.ro_rt->rt_ifa);
> + ifp = ro.ro_rt->rt_ifp;
> + if (ro.ro_rt->rt_flags & RTF_GATEWAY)
> + dst = (struct sockaddr_in *)ro.ro_rt->rt_gateway;
> + } else {
> + ipstat.ips_noroute++;
> + ipstat.ips_cantforward++;
> + icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, NULL, NULL);
> + if (ro.ro_rt)
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> +
> +
> + /**
> + ** Fifth: outgoing firewall packet processing
> + **/
> +
> +#ifdef PFIL_HOOKS
> + /*
> + * Run through list of hooks for output packets.
> + */
> + if (pfil_run_hooks(&inet_pfil_hook, &m, ifp, PFIL_OUT) ||
> + m == NULL) {
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> +
> + M_ASSERTVALID(m);
> + M_ASSERTPKTHDR(m);
> +
> + ip = mtod(m, struct ip *);
> + dest = ip->ip_dst.s_addr;
> +#endif
> + if (fw_enable && IPFW_LOADED && !args.next_hop) {
> + bzero(&args, sizeof(args));
> + args.m = m;
> + args.oif = ifp;
> + ipfw = 0;
> +
> + ipfw = ip_fw_chk_ptr(&args);
> + m = args.m;
> +
> + M_ASSERTVALID(m);
> + M_ASSERTPKTHDR(m);
> +
> + if ( (ipfw & IP_FW_PORT_DENY_FLAG) || m == NULL) {
> + if (m)
> + m_freem(m);
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> + if (DUMMYNET_LOADED && (ipfw & IP_FW_PORT_DYNT_FLAG) != 0) {
#jesper
Whitespace bug, spaces instead of tabs
> + /*
> + * XXX note: if the ifp or rt entry are deleted
> + * while a pkt is in dummynet, we are in trouble!
> + */
> + args.ro = &ro; /* dummynet does not save it */
> + args.dst = dst;
> +
> + ip_dn_io_ptr(m, ipfw & 0xffff, DN_TO_IP_OUT, &args);
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> +#ifdef IPDIVERT
> + if (ipfw != 0 && (ipfw & IP_FW_PORT_DYNT_FLAG) == 0) {
> + /*
> + * See if this is a fragment
> + */
> + if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
> + MGETHDR(tag, M_DONTWAIT, MT_TAG);
> + if (tag == NULL) {
> + m_freem(m);
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> + tag->m_flags = PACKET_TAG_DIVERT;
> + tag->m_data = (caddr_t)(u_int32_t)args.divert_rule;
> + tag->m_next = m;
> + m = tag;
> + tag = NULL;
> +
> + goto droptoours;
> + }
> + /*
> + * Tee packet
> + */
> + if ((ipfw & IP_FW_PORT_TEE_FLAG) != 0)
> + teem = m_dup(m, M_DONTWAIT);
> + else
> + teem = m;
> + if (teem == NULL)
> + goto passout;
> +
> + M_ASSERTVALID(m);
> + M_ASSERTPKTHDR(m);
> +
> + /*
> + * delayed checksums are not compatible with divert
> + */
> + if (teem->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
> + in_delayed_cksum(teem);
> + teem->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
> + }
> + /*
> + * Restore packet header fields to original values
> + */
> + tip = mtod(teem, struct ip *);
> + tip->ip_len = htons(tip->ip_len);
> + tip->ip_off = htons(tip->ip_off);
> + /*
> + * Deliver packet to divert input routine
> + */
> + divert_packet(teem, 0, ipfw & 0xffff, args.divert_rule);
> + /*
> + * If this was not tee, we are done
> + */
> + if ((ipfw & IP_FW_PORT_TEE_FLAG) == 0) {
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> + /* Continue if it was tee */
> + goto passout;
> + }
> +#endif
> + if (ipfw == 0 && args.next_hop != NULL) {
> + dest = args.next_hop->sin_addr.s_addr;
> + goto passout;
> + }
> + /*
> + * Let through or not?
> + */
> + if (ipfw != 0) {
> + m_freem(m);
> + return 1;
> + }
> + }
> +passout:
> + ip = mtod(m, struct ip *);
> +
> + /*
> + * Destination address changed?
> + */
> + if (odest != dest) {
> + /*
> + * Is it now for a local address on this host?
> + */
#jesper
Again, do we really want to look for packets destined for us after being
translated ?
> + LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
> + if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) {
> +forwardlocal:
> + if(args.next_hop) {
> + MGETHDR(tag, M_DONTWAIT, MT_TAG);
> + if (tag == NULL) {
> + m_freem(m);
> + if(ro.ro_rt)
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> + tag->m_flags = PACKET_TAG_IPFORWARD;
> + tag->m_data = (caddr_t)args.next_hop;
> + tag->m_next = m;
> + m = tag;
> + tag = NULL;
> + }
> +#ifdef IPDIVERT
> +droptoours: /* Used for DIVERT */
> +#endif
> + MGETHDR(tag, M_DONTWAIT, MT_TAG);
> + if (tag == NULL) {
> + m_freem(m);
> + if(ro.ro_rt)
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> + tag->m_flags = PACKET_TAG_IPFASTFWD_OURS;
> + tag->m_data = NULL;
> + tag->m_next = m;
#jesper
Whitespace bug, spaces instead of tabs
> + m = tag;
> + tag = NULL;
> +
> +#if 0
> + /*
> + * Do some checks, we never know what fw has
> + * done to it.
> + */
> + if (m->m_pkthdr.rcvif == NULL)
> + m->m_pkthdr.rcvif = ifunit("lo0");
> + if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
> + m->m_pkthdr.csum_flags |=
> + CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
> + m->m_pkthdr.csum_data = 0xffff;
> + }
> + m->m_pkthdr.csum_flags |=
> + CSUM_IP_CHECKED | CSUM_IP_VALID;
> +#endif
> +
> + /* ip still points to the real packet */
> + ip->ip_len = htons(ip->ip_len);
> + ip->ip_off = htons(ip->ip_off);
> +
> + M_ASSERTVALID(m);
> +
> + /*
> + * Drop packet to ip_input
> + */
> + if (ro.ro_rt)
> + RTFREE(ro.ro_rt);
> + return 0;
> + }
> + }
> + /*
> + * Redo route lookup with new destination address
> + */
> + RTFREE(ro.ro_rt);
> + bzero(&ro, sizeof(ro));
> + dst = (struct sockaddr_in *)&ro.ro_dst;
> + dst->sin_family = AF_INET;
> + dst->sin_len = sizeof(*dst);
> + dst->sin_addr.s_addr = dest;
> + rtalloc(&ro);
> +
> + /*
> + * Route there and interface still up?
> + */
> + if ((ro.ro_rt) &&
> + (ro.ro_rt->rt_flags & RTF_UP) &&
> + (ro.ro_rt->rt_ifp->if_flags & IFF_UP)) {
> + ia = ifatoia(ro.ro_rt->rt_ifa);
> + ifp = ro.ro_rt->rt_ifp;
> + if (ro.ro_rt->rt_flags & RTF_GATEWAY)
> + dst = (struct sockaddr_in *)ro.ro_rt->rt_gateway;
> + } else {
> + ipstat.ips_noroute++;
> + ipstat.ips_cantforward++;
> + icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, NULL, NULL);
> + if (ro.ro_rt)
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> + }
> +
> + M_ASSERTVALID(m);
> + M_ASSERTPKTHDR(m);
> +
> + /**
> + ** Sixth: send off the packet
> + **/
> +
> + /*
> + * Check if packet fits MTU or if hardware will fragement for us
> + */
> + if (ip->ip_len <= ifp->if_mtu || (ifp->if_hwassist & CSUM_FRAGMENT &&
> + ((ip->ip_off & IP_DF) == 0))) {
> + /*
> + * Restore packet header fields to original values
> + */
> + ip->ip_len = htons(ip->ip_len);
> + ip->ip_off = htons(ip->ip_off);
> + /*
> + * Send off the packet via outgoing interface
> + */
> + error = (ifp->if_output)(ifp, m, (struct sockaddr *)dst, ro.ro_rt);
> + if (ia) {
> + ia->ia_ifa.if_opackets++;
> + ia->ia_ifa.if_obytes += m->m_pkthdr.len;
> + }
> + } else {
> + /*
> + * Handle EMSGSIZE with icmp reply needfrag for TCP MTU discovery
> + */
> + if (ip->ip_off & IP_DF) {
> + icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG, NULL, ifp);
> + ipstat.ips_cantfrag++;
> + RTFREE(ro.ro_rt);
> + return 1;
> + } else {
> + /*
> + * We have to fragement the packet
> + */
> + m->m_pkthdr.csum_flags |= CSUM_IP;
> + if (ip_fragment(ip, &m, ifp->if_mtu, ifp->if_hwassist,
> + (~ifp->if_hwassist & CSUM_DELAY_IP))) {
> + m_freem(m);
> + RTFREE(ro.ro_rt);
> + return 1;
> + }
> + /*
> + * Send off the fragments via outgoing interface
> + */
> + for (; m; m = m0) {
> + m0 = m->m_nextpkt;
> + m->m_nextpkt = 0;
> +
> + M_ASSERTVALID(m);
> + M_ASSERTPKTHDR(m);
> +
> + if (error == 0) {
> + error = (*ifp->if_output)(ifp, m,
> + (struct sockaddr *)dst, ro.ro_rt);
> + if (ia) {
> + ia->ia_ifa.if_opackets++;
> + ia->ia_ifa.if_obytes += m->m_pkthdr.len;
> + }
> + } else {
> + m_freem(m);
> + }
> + }
> + if (error == 0)
> + ipstat.ips_fragmented++;
> + }
> + }
> +
> + if (error == ENOBUFS)
> + ipstat.ips_odropped++;
> + else if (error != 0)
> + ipstat.ips_odropped++;
> + else {
> + ro.ro_rt->rt_rmx.rmx_pksent++;
> + ipstat.ips_forward++;
> + ipstat.ips_fastforward++;
> + }
> + RTFREE(ro.ro_rt);
> + return 1;
> +}
> +
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