--- v2.4.16/linux/include/net/ip_fib.h Tue Nov 13 01:24:05 2001 +++ linux/include/net/ip_fib.h Tue Dec 4 02:23:20 2001 @@ -203,7 +203,7 @@ extern int inet_rtm_getroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg); extern int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb); extern int fib_validate_source(u32 src, u32 dst, u8 tos, int oif, - struct net_device *dev, u32 *spec_dst, u32 *itag); + struct net_device *dev, u32 *spec_dst, u32 *itag, int our); extern void fib_select_multipath(const struct rt_key *key, struct fib_result *res); /* Exported by fib_semantics.c */ --- v2.4.16/linux/include/linux/in_route.h Fri Jun 12 05:52:33 1998 +++ linux/include/linux/in_route.h Tue Dec 4 01:53:42 2001 @@ -13,6 +13,7 @@ #define RTCF_DIRECTDST 0x00020000 #define RTCF_REDIRECTED 0x00040000 #define RTCF_TPROXY 0x00080000 +#define RTCF_NOARP 0x00100000 #define RTCF_FAST 0x00200000 #define RTCF_MASQ 0x00400000 --- v2.4.16/linux/include/linux/inetdevice.h Tue Nov 13 01:27:21 2001 +++ linux/include/linux/inetdevice.h Tue Dec 4 01:29:02 2001 @@ -17,7 +17,9 @@ int forwarding; int mc_forwarding; int tag; + int hidden; int arp_filter; + int forward_shared; void *sysctl; }; @@ -44,6 +46,7 @@ #define IN_DEV_LOG_MARTIANS(in_dev) (ipv4_devconf.log_martians || (in_dev)->cnf.log_martians) #define IN_DEV_PROXY_ARP(in_dev) (ipv4_devconf.proxy_arp || (in_dev)->cnf.proxy_arp) +#define IN_DEV_HIDDEN(in_dev) ((in_dev)->cnf.hidden && ipv4_devconf.hidden) #define IN_DEV_SHARED_MEDIA(in_dev) (ipv4_devconf.shared_media || (in_dev)->cnf.shared_media) #define IN_DEV_TX_REDIRECTS(in_dev) (ipv4_devconf.send_redirects || (in_dev)->cnf.send_redirects) #define IN_DEV_SEC_REDIRECTS(in_dev) (ipv4_devconf.secure_redirects || (in_dev)->cnf.secure_redirects) @@ -56,6 +59,8 @@ (ipv4_devconf.accept_redirects || (in_dev)->cnf.accept_redirects))) #define IN_DEV_ARPFILTER(in_dev) (ipv4_devconf.arp_filter || (in_dev)->cnf.arp_filter) + +#define IN_DEV_FORWARD_SHARED(in_dev) ((in_dev)->cnf.forward_shared && ipv4_devconf.forward_shared) struct in_ifaddr { --- v2.4.16/linux/include/linux/rtnetlink.h Tue Nov 13 01:27:21 2001 +++ linux/include/linux/rtnetlink.h Tue Dec 4 02:17:08 2001 @@ -167,6 +167,7 @@ #define RTM_F_NOTIFY 0x100 /* Notify user of route change */ #define RTM_F_CLONED 0x200 /* This route is cloned */ #define RTM_F_EQUALIZE 0x400 /* Multipath equalizer: NI */ +#define RTM_F_NOARP 0x800 /* Disable ARP for this route */ /* Reserved table identifiers */ @@ -315,6 +316,7 @@ /* ifa_flags */ #define IFA_F_SECONDARY 0x01 +#define IFA_F_HIDDEN 0x02 #define IFA_F_DEPRECATED 0x20 #define IFA_F_TENTATIVE 0x40 --- v2.4.16/linux/include/linux/sysctl.h Mon Nov 26 23:06:56 2001 +++ linux/include/linux/sysctl.h Tue Dec 4 02:13:49 2001 @@ -334,7 +334,9 @@ NET_IPV4_CONF_BOOTP_RELAY=10, NET_IPV4_CONF_LOG_MARTIANS=11, NET_IPV4_CONF_TAG=12, - NET_IPV4_CONF_ARPFILTER=13 + NET_IPV4_CONF_ARPFILTER=13, + NET_IPV4_CONF_HIDDEN=14, + NET_IPV4_CONF_FORWARD_SHARED=15, }; /* /proc/sys/net/ipv6 */ --- v2.4.16/linux/net/ipv4/arp.c Tue Nov 13 01:28:51 2001 +++ linux/net/ipv4/arp.c Tue Dec 4 02:26:27 2001 @@ -66,6 +66,9 @@ * Alexey Kuznetsov: new arp state machine; * now it is in net/core/neighbour.c. * Krzysztof Halasa: Added Frame Relay ARP support. + * Julian Anastasov: "hidden" flag: hide the + * interface and don't reply for it + * Julian Anastasov: Per-route ARP control */ #include @@ -321,11 +324,34 @@ struct net_device *dev = neigh->dev; u32 target = *(u32*)neigh->primary_key; int probes = atomic_read(&neigh->probes); + struct rtable *rt; - if (skb && inet_addr_type(skb->nh.iph->saddr) == RTN_LOCAL) - saddr = skb->nh.iph->saddr; - else - saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); + /* Determine source IP for the probing packet. */ + saddr = 0; + if (skb != NULL) { + struct in_device *in_dev2 = NULL; + struct net_device *dev2 = NULL; + + rt = (struct rtable*)skb->dst; + if (rt && !rt->rt_iif && !(rt->rt_flags & RTCF_NOARP) && + (dev2 = ip_dev_find(skb->nh.iph->saddr)) != NULL && + (in_dev2 = in_dev_get(dev2)) != NULL && + !IN_DEV_HIDDEN(in_dev2)) + saddr = rt->rt_src; + if (dev2) { + if (in_dev2) in_dev_put(in_dev2); + dev_put(dev2); + } + } + if (!saddr) { + if (ip_route_output(&rt, target, 0, 0, dev->ifindex) < 0) + /* Never send probes with 0 source as we used to. */ + return; + saddr = rt->rt_src; + ip_rt_put(rt); + } + if (!saddr) + return; if ((probes -= neigh->parms->ucast_probes) < 0) { if (!(neigh->nud_state&NUD_VALID)) @@ -345,20 +371,35 @@ read_unlock_bh(&neigh->lock); } -static int arp_filter(__u32 sip, __u32 tip, struct net_device *dev) +static int arp_filter(struct sk_buff *skb, __u32 sip, __u32 tip, + struct in_device *in_dev) { struct rtable *rt; int flag = 0; - /*unsigned long now; */ + if (!IN_DEV_ARPFILTER(in_dev)) + return 0; + + /* Always answer direct queries. */ + if (skb->pkt_type == PACKET_HOST) + return 0; + + /* Then check routes: + * primarily, this check is used to not to answer to some requests if + * several interfaces are connected to the same segment. + * This check also may be used for manual control of who sees IP + * addresses at which link-level addresses by installing prohibiting + * routes. -- 2001/05/20 SAW + */ if (ip_route_output(&rt, sip, tip, 0, 0) < 0) return 1; - if (rt->u.dst.dev != dev) { + if (rt->u.dst.dev != in_dev->dev) { NET_INC_STATS_BH(ArpFilter); flag = 1; } ip_rt_put(rt); - return flag; + + return flag; } /* OBSOLETE FUNCTIONS */ @@ -741,9 +782,22 @@ /* Special case: IPv4 duplicate address detection packet (RFC2131) */ if (sip == 0) { - if (arp->ar_op == __constant_htons(ARPOP_REQUEST) && - inet_addr_type(tip) == RTN_LOCAL) + int reply; + struct net_device *dev2 = NULL; + struct in_device *in_dev2 = NULL; + + reply = + (arp->ar_op == __constant_htons(ARPOP_REQUEST) && + (dev2 = ip_dev_find(tip)) != NULL && + (dev2 == dev || + ((in_dev2 = in_dev_get(dev2)) != NULL && + !IN_DEV_HIDDEN(in_dev2)))); + if (dev2) { + if (in_dev2) in_dev_put(in_dev2); + dev_put(dev2); + if (reply) arp_send(ARPOP_REPLY,ETH_P_ARP,tip,dev,tip,sha,dev->dev_addr,dev->dev_addr); + } goto out; } @@ -757,8 +811,23 @@ n = neigh_event_ns(&arp_tbl, sha, &sip, dev); if (n) { int dont_send = 0; - if (IN_DEV_ARPFILTER(in_dev)) - dont_send |= arp_filter(sip,tip,dev); + if (ipv4_devconf.hidden && + skb->pkt_type != PACKET_HOST) { + struct net_device *dev2 = NULL; + struct in_device *in_dev2 = NULL; + + dont_send |= + ((dev2 = ip_dev_find(tip)) != NULL && + dev2 != dev && + (in_dev2=in_dev_get(dev2)) != NULL && + IN_DEV_HIDDEN(in_dev2)); + if (dev2) { + if (in_dev2) in_dev_put(in_dev2); + dev_put(dev2); + } + } + dont_send |= rt->rt_flags & RTCF_NOARP || + arp_filter(skb,sip,tip,in_dev); if (!dont_send) arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha); @@ -772,6 +841,9 @@ n = neigh_event_ns(&arp_tbl, sha, &sip, dev); if (n) neigh_release(n); + + if (rt->rt_flags & RTCF_NOARP) + goto out; if (skb->stamp.tv_sec == 0 || skb->pkt_type == PACKET_HOST || --- v2.4.16/linux/net/ipv4/devinet.c Tue Nov 13 01:29:33 2001 +++ linux/net/ipv4/devinet.c Tue Dec 4 01:29:02 2001 @@ -764,7 +764,8 @@ read_lock(&in_dev->lock); for_primary_ifa(in_dev) { - if (ifa->ifa_scope != RT_SCOPE_LINK && + if (!IN_DEV_HIDDEN(in_dev) && + ifa->ifa_scope != RT_SCOPE_LINK && ifa->ifa_scope <= scope) { read_unlock(&in_dev->lock); read_unlock(&inetdev_lock); @@ -1044,7 +1045,7 @@ static struct devinet_sysctl_table { struct ctl_table_header *sysctl_header; - ctl_table devinet_vars[14]; + ctl_table devinet_vars[16]; ctl_table devinet_dev[2]; ctl_table devinet_conf_dir[2]; ctl_table devinet_proto_dir[2]; @@ -1087,8 +1088,14 @@ {NET_IPV4_CONF_TAG, "tag", &ipv4_devconf.tag, sizeof(int), 0644, NULL, &proc_dointvec}, + {NET_IPV4_CONF_HIDDEN, "hidden", + &ipv4_devconf.hidden, sizeof(int), 0644, NULL, + &proc_dointvec}, {NET_IPV4_CONF_ARPFILTER, "arp_filter", &ipv4_devconf.arp_filter, sizeof(int), 0644, NULL, + &proc_dointvec}, + {NET_IPV4_CONF_FORWARD_SHARED, "forward_shared", + &ipv4_devconf.forward_shared, sizeof(int), 0644, NULL, &proc_dointvec}, {0}}, --- v2.4.16/linux/net/ipv4/fib_frontend.c Tue Nov 13 01:26:34 2001 +++ linux/net/ipv4/fib_frontend.c Tue Dec 4 01:53:42 2001 @@ -204,13 +204,15 @@ */ int fib_validate_source(u32 src, u32 dst, u8 tos, int oif, - struct net_device *dev, u32 *spec_dst, u32 *itag) + struct net_device *dev, u32 *spec_dst, u32 *itag, + int our) { struct in_device *in_dev; struct rt_key key; struct fib_result res; int no_addr, rpf; int ret; + int fwdsh = 0; key.dst = src; key.src = dst; @@ -225,6 +227,7 @@ if (in_dev) { no_addr = in_dev->ifa_list == NULL; rpf = IN_DEV_RPFILTER(in_dev); + fwdsh = IN_DEV_FORWARD_SHARED(in_dev); } read_unlock(&inetdev_lock); @@ -233,7 +236,12 @@ if (fib_lookup(&key, &res)) goto last_resort; - if (res.type != RTN_UNICAST) + if (fwdsh) { + fwdsh = (res.type == RTN_LOCAL && !our); + if (fwdsh) + rpf = 0; + } + if (res.type != RTN_UNICAST && !fwdsh) goto e_inval_res; *spec_dst = FIB_RES_PREFSRC(res); fib_combine_itag(itag, &res); @@ -253,6 +261,8 @@ if (rpf) goto e_inval; key.oif = dev->ifindex; + if (fwdsh) + key.iif = loopback_dev.ifindex; ret = 0; if (fib_lookup(&key, &res) == 0) { @@ -449,6 +459,9 @@ req.rtm.rtm_protocol = RTPROT_KERNEL; req.rtm.rtm_scope = (type != RTN_LOCAL ? RT_SCOPE_LINK : RT_SCOPE_HOST); req.rtm.rtm_type = type; + if (ifa->ifa_flags & IFA_F_HIDDEN && type == RTN_LOCAL && + cmd == RTM_NEWROUTE) + req.rtm.rtm_flags |= RTM_F_NOARP; rta.rta_dst = &dst; rta.rta_prefsrc = &ifa->ifa_local; --- v2.4.16/linux/net/ipv4/route.c Tue Nov 13 01:30:32 2001 +++ linux/net/ipv4/route.c Tue Dec 4 01:53:42 2001 @@ -1240,7 +1240,7 @@ goto e_inval; spec_dst = inet_select_addr(dev, 0, RT_SCOPE_LINK); } else if (fib_validate_source(saddr, 0, tos, 0, - dev, &spec_dst, &itag) < 0) + dev, &spec_dst, &itag, our) < 0) goto e_inval; rth = dst_alloc(&ipv4_dst_ops); @@ -1400,11 +1400,14 @@ if (res.type == RTN_BROADCAST) goto brd_input; + if (res.fi && res.fi->fib_flags & RTM_F_NOARP) + flags |= RTCF_NOARP; + if (res.type == RTN_LOCAL) { int result; result = fib_validate_source(saddr, daddr, tos, loopback_dev.ifindex, - dev, &spec_dst, &itag); + dev, &spec_dst, &itag, 1); if (result < 0) goto martian_source; if (result) @@ -1431,7 +1434,7 @@ } err = fib_validate_source(saddr, daddr, tos, FIB_RES_OIF(res), dev, - &spec_dst, &itag); + &spec_dst, &itag, 0); if (err < 0) goto martian_source; @@ -1515,7 +1518,7 @@ spec_dst = inet_select_addr(dev, 0, RT_SCOPE_LINK); else { err = fib_validate_source(saddr, 0, tos, 0, dev, &spec_dst, - &itag); + &itag, 1); if (err < 0) goto martian_source; if (err) @@ -1836,6 +1839,9 @@ if (res.type == RTN_NAT) goto e_inval; + if (res.fi && res.fi->fib_flags & RTM_F_NOARP) + flags |= RTCF_NOARP; + if (res.type == RTN_LOCAL) { if (!key.src) key.src = key.dst; @@ -2039,6 +2045,8 @@ r->rtm_flags = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED; if (rt->rt_flags & RTCF_NOTIFY) r->rtm_flags |= RTM_F_NOTIFY; + if (rt->rt_flags & RTCF_NOARP) + r->rtm_flags |= RTM_F_NOARP; RTA_PUT(skb, RTA_DST, 4, &rt->rt_dst); if (rt->key.src) { r->rtm_src_len = 32; @@ -2165,6 +2173,8 @@ skb->dst = &rt->u.dst; if (rtm->rtm_flags & RTM_F_NOTIFY) rt->rt_flags |= RTCF_NOTIFY; + if (rtm->rtm_flags & RTM_F_NOARP) + rt->rt_flags |= RTCF_NOARP; NETLINK_CB(skb).dst_pid = NETLINK_CB(in_skb).pid; --- v2.4.16/linux/Documentation/filesystems/proc.txt Mon Nov 26 23:05:49 2001 +++ linux/Documentation/filesystems/proc.txt Tue Dec 4 01:29:02 2001 @@ -1566,6 +1566,18 @@ (external addresses can still be spoofed), without the need for additional firewall rules. +forward_shared +-------------- + +Integer value determines if a source validation should allow forwarding +of packets with local source address. 1 means yes, 0 means no. By default +the flag is disabled and such packets are not forwarded. + +If you enable this flag on internal network, the router will forward +packets from internal hosts with shared IP addresses no matter how +the rp_filter is set. This flag is activated only if it is enabled +both in specific device section and in "all" section. + secure_redirects ---------------- @@ -1582,6 +1594,16 @@ -------------- Determines whether to send ICMP redirects to other hosts. + +hidden +------ + +Hide addresses attached to this device from another devices. +Such addresses will never be selected by source address autoselection +mechanism, host does not answer broadcast ARP requests for them, +does not announce it as source address of ARP requests, but they +are still reachable via IP. This flag is activated only if it is +enabled both in specific device section and in "all" section. Routing settings ---------------- --- v2.4.16/linux/Documentation/networking/ip-sysctl.txt Tue Nov 13 01:25:32 2001 +++ linux/Documentation/networking/ip-sysctl.txt Tue Dec 4 01:29:02 2001 @@ -347,6 +347,17 @@ forwarding - BOOLEAN Enable IP forwarding on this interface. +forward_shared - BOOLEAN + Integer value determines if a source validation should allow + forwarding of packets with local source address. 1 means yes, + 0 means no. By default the flag is disabled and such packets + are not forwarded. + + If you enable this flag on internal network, the router will forward + packets from internal hosts with shared IP addresses no matter how + the rp_filter is set. This flag is activated only if it is + enabled both in specific device section and in "all" section. + mc_forwarding - BOOLEAN Do multicast routing. The kernel needs to be compiled with CONFIG_MROUTE and a multicast routing daemon is required. @@ -391,6 +402,14 @@ Default value is 0. Note that some distributions enable it in startip scripts. + +hidden - BOOLEAN + Hide addresses attached to this device from another devices. + Such addresses will never be selected by source address autoselection + mechanism, host does not answer broadcast ARP requests for them, + does not announce it as source address of ARP requests, but they + are still reachable via IP. This flag is activated only if it is + enabled both in specific device section and in "all" section. Alexey Kuznetsov. kuznet@ms2.inr.ac.ru