| /* |
| * Linux NET3: GRE over IP protocol decoder. |
| * |
| * Authors: Alexey Kuznetsov (kuznet@ms2.inr.ac.ru) |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| * |
| */ |
| |
| #include <linux/capability.h> |
| #include <linux/module.h> |
| #include <linux/types.h> |
| #include <linux/kernel.h> |
| #include <asm/uaccess.h> |
| #include <linux/skbuff.h> |
| #include <linux/netdevice.h> |
| #include <linux/in.h> |
| #include <linux/tcp.h> |
| #include <linux/udp.h> |
| #include <linux/if_arp.h> |
| #include <linux/mroute.h> |
| #include <linux/init.h> |
| #include <linux/in6.h> |
| #include <linux/inetdevice.h> |
| #include <linux/igmp.h> |
| #include <linux/netfilter_ipv4.h> |
| #include <linux/if_ether.h> |
| |
| #include <net/sock.h> |
| #include <net/ip.h> |
| #include <net/icmp.h> |
| #include <net/protocol.h> |
| #include <net/ipip.h> |
| #include <net/arp.h> |
| #include <net/checksum.h> |
| #include <net/dsfield.h> |
| #include <net/inet_ecn.h> |
| #include <net/xfrm.h> |
| |
| #ifdef CONFIG_IPV6 |
| #include <net/ipv6.h> |
| #include <net/ip6_fib.h> |
| #include <net/ip6_route.h> |
| #endif |
| |
| /* |
| Problems & solutions |
| -------------------- |
| |
| 1. The most important issue is detecting local dead loops. |
| They would cause complete host lockup in transmit, which |
| would be "resolved" by stack overflow or, if queueing is enabled, |
| with infinite looping in net_bh. |
| |
| We cannot track such dead loops during route installation, |
| it is infeasible task. The most general solutions would be |
| to keep skb->encapsulation counter (sort of local ttl), |
| and silently drop packet when it expires. It is the best |
| solution, but it supposes maintaing new variable in ALL |
| skb, even if no tunneling is used. |
| |
| Current solution: t->recursion lock breaks dead loops. It looks |
| like dev->tbusy flag, but I preferred new variable, because |
| the semantics is different. One day, when hard_start_xmit |
| will be multithreaded we will have to use skb->encapsulation. |
| |
| |
| |
| 2. Networking dead loops would not kill routers, but would really |
| kill network. IP hop limit plays role of "t->recursion" in this case, |
| if we copy it from packet being encapsulated to upper header. |
| It is very good solution, but it introduces two problems: |
| |
| - Routing protocols, using packets with ttl=1 (OSPF, RIP2), |
| do not work over tunnels. |
| - traceroute does not work. I planned to relay ICMP from tunnel, |
| so that this problem would be solved and traceroute output |
| would even more informative. This idea appeared to be wrong: |
| only Linux complies to rfc1812 now (yes, guys, Linux is the only |
| true router now :-)), all routers (at least, in neighbourhood of mine) |
| return only 8 bytes of payload. It is the end. |
| |
| Hence, if we want that OSPF worked or traceroute said something reasonable, |
| we should search for another solution. |
| |
| One of them is to parse packet trying to detect inner encapsulation |
| made by our node. It is difficult or even impossible, especially, |
| taking into account fragmentation. TO be short, tt is not solution at all. |
| |
| Current solution: The solution was UNEXPECTEDLY SIMPLE. |
| We force DF flag on tunnels with preconfigured hop limit, |
| that is ALL. :-) Well, it does not remove the problem completely, |
| but exponential growth of network traffic is changed to linear |
| (branches, that exceed pmtu are pruned) and tunnel mtu |
| fastly degrades to value <68, where looping stops. |
| Yes, it is not good if there exists a router in the loop, |
| which does not force DF, even when encapsulating packets have DF set. |
| But it is not our problem! Nobody could accuse us, we made |
| all that we could make. Even if it is your gated who injected |
| fatal route to network, even if it were you who configured |
| fatal static route: you are innocent. :-) |
| |
| |
| |
| 3. Really, ipv4/ipip.c, ipv4/ip_gre.c and ipv6/sit.c contain |
| practically identical code. It would be good to glue them |
| together, but it is not very evident, how to make them modular. |
| sit is integral part of IPv6, ipip and gre are naturally modular. |
| We could extract common parts (hash table, ioctl etc) |
| to a separate module (ip_tunnel.c). |
| |
| Alexey Kuznetsov. |
| */ |
| |
| static int ipgre_tunnel_init(struct net_device *dev); |
| static void ipgre_tunnel_setup(struct net_device *dev); |
| |
| /* Fallback tunnel: no source, no destination, no key, no options */ |
| |
| static int ipgre_fb_tunnel_init(struct net_device *dev); |
| |
| static struct net_device *ipgre_fb_tunnel_dev; |
| |
| /* Tunnel hash table */ |
| |
| /* |
| 4 hash tables: |
| |
| 3: (remote,local) |
| 2: (remote,*) |
| 1: (*,local) |
| 0: (*,*) |
| |
| We require exact key match i.e. if a key is present in packet |
| it will match only tunnel with the same key; if it is not present, |
| it will match only keyless tunnel. |
| |
| All keysless packets, if not matched configured keyless tunnels |
| will match fallback tunnel. |
| */ |
| |
| #define HASH_SIZE 16 |
| #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF) |
| |
| static struct ip_tunnel *tunnels[4][HASH_SIZE]; |
| |
| #define tunnels_r_l (tunnels[3]) |
| #define tunnels_r (tunnels[2]) |
| #define tunnels_l (tunnels[1]) |
| #define tunnels_wc (tunnels[0]) |
| |
| static DEFINE_RWLOCK(ipgre_lock); |
| |
| /* Given src, dst and key, find appropriate for input tunnel. */ |
| |
| static struct ip_tunnel * ipgre_tunnel_lookup(__be32 remote, __be32 local, __be32 key) |
| { |
| unsigned h0 = HASH(remote); |
| unsigned h1 = HASH(key); |
| struct ip_tunnel *t; |
| |
| for (t = tunnels_r_l[h0^h1]; t; t = t->next) { |
| if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) { |
| if (t->parms.i_key == key && (t->dev->flags&IFF_UP)) |
| return t; |
| } |
| } |
| for (t = tunnels_r[h0^h1]; t; t = t->next) { |
| if (remote == t->parms.iph.daddr) { |
| if (t->parms.i_key == key && (t->dev->flags&IFF_UP)) |
| return t; |
| } |
| } |
| for (t = tunnels_l[h1]; t; t = t->next) { |
| if (local == t->parms.iph.saddr || |
| (local == t->parms.iph.daddr && |
| ipv4_is_multicast(local))) { |
| if (t->parms.i_key == key && (t->dev->flags&IFF_UP)) |
| return t; |
| } |
| } |
| for (t = tunnels_wc[h1]; t; t = t->next) { |
| if (t->parms.i_key == key && (t->dev->flags&IFF_UP)) |
| return t; |
| } |
| |
| if (ipgre_fb_tunnel_dev->flags&IFF_UP) |
| return netdev_priv(ipgre_fb_tunnel_dev); |
| return NULL; |
| } |
| |
| static struct ip_tunnel **__ipgre_bucket(struct ip_tunnel_parm *parms) |
| { |
| __be32 remote = parms->iph.daddr; |
| __be32 local = parms->iph.saddr; |
| __be32 key = parms->i_key; |
| unsigned h = HASH(key); |
| int prio = 0; |
| |
| if (local) |
| prio |= 1; |
| if (remote && !ipv4_is_multicast(remote)) { |
| prio |= 2; |
| h ^= HASH(remote); |
| } |
| |
| return &tunnels[prio][h]; |
| } |
| |
| static inline struct ip_tunnel **ipgre_bucket(struct ip_tunnel *t) |
| { |
| return __ipgre_bucket(&t->parms); |
| } |
| |
| static void ipgre_tunnel_link(struct ip_tunnel *t) |
| { |
| struct ip_tunnel **tp = ipgre_bucket(t); |
| |
| t->next = *tp; |
| write_lock_bh(&ipgre_lock); |
| *tp = t; |
| write_unlock_bh(&ipgre_lock); |
| } |
| |
| static void ipgre_tunnel_unlink(struct ip_tunnel *t) |
| { |
| struct ip_tunnel **tp; |
| |
| for (tp = ipgre_bucket(t); *tp; tp = &(*tp)->next) { |
| if (t == *tp) { |
| write_lock_bh(&ipgre_lock); |
| *tp = t->next; |
| write_unlock_bh(&ipgre_lock); |
| break; |
| } |
| } |
| } |
| |
| static struct ip_tunnel * ipgre_tunnel_locate(struct ip_tunnel_parm *parms, int create) |
| { |
| __be32 remote = parms->iph.daddr; |
| __be32 local = parms->iph.saddr; |
| __be32 key = parms->i_key; |
| struct ip_tunnel *t, **tp, *nt; |
| struct net_device *dev; |
| char name[IFNAMSIZ]; |
| |
| for (tp = __ipgre_bucket(parms); (t = *tp) != NULL; tp = &t->next) { |
| if (local == t->parms.iph.saddr && remote == t->parms.iph.daddr) { |
| if (key == t->parms.i_key) |
| return t; |
| } |
| } |
| if (!create) |
| return NULL; |
| |
| if (parms->name[0]) |
| strlcpy(name, parms->name, IFNAMSIZ); |
| else |
| sprintf(name, "gre%%d"); |
| |
| dev = alloc_netdev(sizeof(*t), name, ipgre_tunnel_setup); |
| if (!dev) |
| return NULL; |
| |
| dev->init = ipgre_tunnel_init; |
| nt = netdev_priv(dev); |
| nt->parms = *parms; |
| |
| if (register_netdevice(dev) < 0) { |
| free_netdev(dev); |
| goto failed; |
| } |
| |
| dev_hold(dev); |
| ipgre_tunnel_link(nt); |
| return nt; |
| |
| failed: |
| return NULL; |
| } |
| |
| static void ipgre_tunnel_uninit(struct net_device *dev) |
| { |
| ipgre_tunnel_unlink(netdev_priv(dev)); |
| dev_put(dev); |
| } |
| |
| |
| static void ipgre_err(struct sk_buff *skb, u32 info) |
| { |
| #ifndef I_WISH_WORLD_WERE_PERFECT |
| |
| /* It is not :-( All the routers (except for Linux) return only |
| 8 bytes of packet payload. It means, that precise relaying of |
| ICMP in the real Internet is absolutely infeasible. |
| |
| Moreover, Cisco "wise men" put GRE key to the third word |
| in GRE header. It makes impossible maintaining even soft state for keyed |
| GRE tunnels with enabled checksum. Tell them "thank you". |
| |
| Well, I wonder, rfc1812 was written by Cisco employee, |
| what the hell these idiots break standrads established |
| by themself??? |
| */ |
| |
| struct iphdr *iph = (struct iphdr*)skb->data; |
| __be16 *p = (__be16*)(skb->data+(iph->ihl<<2)); |
| int grehlen = (iph->ihl<<2) + 4; |
| const int type = icmp_hdr(skb)->type; |
| const int code = icmp_hdr(skb)->code; |
| struct ip_tunnel *t; |
| __be16 flags; |
| |
| flags = p[0]; |
| if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) { |
| if (flags&(GRE_VERSION|GRE_ROUTING)) |
| return; |
| if (flags&GRE_KEY) { |
| grehlen += 4; |
| if (flags&GRE_CSUM) |
| grehlen += 4; |
| } |
| } |
| |
| /* If only 8 bytes returned, keyed message will be dropped here */ |
| if (skb_headlen(skb) < grehlen) |
| return; |
| |
| switch (type) { |
| default: |
| case ICMP_PARAMETERPROB: |
| return; |
| |
| case ICMP_DEST_UNREACH: |
| switch (code) { |
| case ICMP_SR_FAILED: |
| case ICMP_PORT_UNREACH: |
| /* Impossible event. */ |
| return; |
| case ICMP_FRAG_NEEDED: |
| /* Soft state for pmtu is maintained by IP core. */ |
| return; |
| default: |
| /* All others are translated to HOST_UNREACH. |
| rfc2003 contains "deep thoughts" about NET_UNREACH, |
| I believe they are just ether pollution. --ANK |
| */ |
| break; |
| } |
| break; |
| case ICMP_TIME_EXCEEDED: |
| if (code != ICMP_EXC_TTL) |
| return; |
| break; |
| } |
| |
| read_lock(&ipgre_lock); |
| t = ipgre_tunnel_lookup(iph->daddr, iph->saddr, (flags&GRE_KEY) ? *(((__be32*)p) + (grehlen>>2) - 1) : 0); |
| if (t == NULL || t->parms.iph.daddr == 0 || |
| ipv4_is_multicast(t->parms.iph.daddr)) |
| goto out; |
| |
| if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED) |
| goto out; |
| |
| if (jiffies - t->err_time < IPTUNNEL_ERR_TIMEO) |
| t->err_count++; |
| else |
| t->err_count = 1; |
| t->err_time = jiffies; |
| out: |
| read_unlock(&ipgre_lock); |
| return; |
| #else |
| struct iphdr *iph = (struct iphdr*)dp; |
| struct iphdr *eiph; |
| __be16 *p = (__be16*)(dp+(iph->ihl<<2)); |
| const int type = icmp_hdr(skb)->type; |
| const int code = icmp_hdr(skb)->code; |
| int rel_type = 0; |
| int rel_code = 0; |
| __be32 rel_info = 0; |
| __u32 n = 0; |
| __be16 flags; |
| int grehlen = (iph->ihl<<2) + 4; |
| struct sk_buff *skb2; |
| struct flowi fl; |
| struct rtable *rt; |
| |
| if (p[1] != htons(ETH_P_IP)) |
| return; |
| |
| flags = p[0]; |
| if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) { |
| if (flags&(GRE_VERSION|GRE_ROUTING)) |
| return; |
| if (flags&GRE_CSUM) |
| grehlen += 4; |
| if (flags&GRE_KEY) |
| grehlen += 4; |
| if (flags&GRE_SEQ) |
| grehlen += 4; |
| } |
| if (len < grehlen + sizeof(struct iphdr)) |
| return; |
| eiph = (struct iphdr*)(dp + grehlen); |
| |
| switch (type) { |
| default: |
| return; |
| case ICMP_PARAMETERPROB: |
| n = ntohl(icmp_hdr(skb)->un.gateway) >> 24; |
| if (n < (iph->ihl<<2)) |
| return; |
| |
| /* So... This guy found something strange INSIDE encapsulated |
| packet. Well, he is fool, but what can we do ? |
| */ |
| rel_type = ICMP_PARAMETERPROB; |
| n -= grehlen; |
| rel_info = htonl(n << 24); |
| break; |
| |
| case ICMP_DEST_UNREACH: |
| switch (code) { |
| case ICMP_SR_FAILED: |
| case ICMP_PORT_UNREACH: |
| /* Impossible event. */ |
| return; |
| case ICMP_FRAG_NEEDED: |
| /* And it is the only really necessary thing :-) */ |
| n = ntohs(icmp_hdr(skb)->un.frag.mtu); |
| if (n < grehlen+68) |
| return; |
| n -= grehlen; |
| /* BSD 4.2 MORE DOES NOT EXIST IN NATURE. */ |
| if (n > ntohs(eiph->tot_len)) |
| return; |
| rel_info = htonl(n); |
| break; |
| default: |
| /* All others are translated to HOST_UNREACH. |
| rfc2003 contains "deep thoughts" about NET_UNREACH, |
| I believe, it is just ether pollution. --ANK |
| */ |
| rel_type = ICMP_DEST_UNREACH; |
| rel_code = ICMP_HOST_UNREACH; |
| break; |
| } |
| break; |
| case ICMP_TIME_EXCEEDED: |
| if (code != ICMP_EXC_TTL) |
| return; |
| break; |
| } |
| |
| /* Prepare fake skb to feed it to icmp_send */ |
| skb2 = skb_clone(skb, GFP_ATOMIC); |
| if (skb2 == NULL) |
| return; |
| dst_release(skb2->dst); |
| skb2->dst = NULL; |
| skb_pull(skb2, skb->data - (u8*)eiph); |
| skb_reset_network_header(skb2); |
| |
| /* Try to guess incoming interface */ |
| memset(&fl, 0, sizeof(fl)); |
| fl.fl4_dst = eiph->saddr; |
| fl.fl4_tos = RT_TOS(eiph->tos); |
| fl.proto = IPPROTO_GRE; |
| if (ip_route_output_key(&init_net, &rt, &fl)) { |
| kfree_skb(skb2); |
| return; |
| } |
| skb2->dev = rt->u.dst.dev; |
| |
| /* route "incoming" packet */ |
| if (rt->rt_flags&RTCF_LOCAL) { |
| ip_rt_put(rt); |
| rt = NULL; |
| fl.fl4_dst = eiph->daddr; |
| fl.fl4_src = eiph->saddr; |
| fl.fl4_tos = eiph->tos; |
| if (ip_route_output_key(&init_net, &rt, &fl) || |
| rt->u.dst.dev->type != ARPHRD_IPGRE) { |
| ip_rt_put(rt); |
| kfree_skb(skb2); |
| return; |
| } |
| } else { |
| ip_rt_put(rt); |
| if (ip_route_input(skb2, eiph->daddr, eiph->saddr, eiph->tos, skb2->dev) || |
| skb2->dst->dev->type != ARPHRD_IPGRE) { |
| kfree_skb(skb2); |
| return; |
| } |
| } |
| |
| /* change mtu on this route */ |
| if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) { |
| if (n > dst_mtu(skb2->dst)) { |
| kfree_skb(skb2); |
| return; |
| } |
| skb2->dst->ops->update_pmtu(skb2->dst, n); |
| } else if (type == ICMP_TIME_EXCEEDED) { |
| struct ip_tunnel *t = netdev_priv(skb2->dev); |
| if (t->parms.iph.ttl) { |
| rel_type = ICMP_DEST_UNREACH; |
| rel_code = ICMP_HOST_UNREACH; |
| } |
| } |
| |
| icmp_send(skb2, rel_type, rel_code, rel_info); |
| kfree_skb(skb2); |
| #endif |
| } |
| |
| static inline void ipgre_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb) |
| { |
| if (INET_ECN_is_ce(iph->tos)) { |
| if (skb->protocol == htons(ETH_P_IP)) { |
| IP_ECN_set_ce(ip_hdr(skb)); |
| } else if (skb->protocol == htons(ETH_P_IPV6)) { |
| IP6_ECN_set_ce(ipv6_hdr(skb)); |
| } |
| } |
| } |
| |
| static inline u8 |
| ipgre_ecn_encapsulate(u8 tos, struct iphdr *old_iph, struct sk_buff *skb) |
| { |
| u8 inner = 0; |
| if (skb->protocol == htons(ETH_P_IP)) |
| inner = old_iph->tos; |
| else if (skb->protocol == htons(ETH_P_IPV6)) |
| inner = ipv6_get_dsfield((struct ipv6hdr *)old_iph); |
| return INET_ECN_encapsulate(tos, inner); |
| } |
| |
| static int ipgre_rcv(struct sk_buff *skb) |
| { |
| struct iphdr *iph; |
| u8 *h; |
| __be16 flags; |
| __sum16 csum = 0; |
| __be32 key = 0; |
| u32 seqno = 0; |
| struct ip_tunnel *tunnel; |
| int offset = 4; |
| |
| if (!pskb_may_pull(skb, 16)) |
| goto drop_nolock; |
| |
| iph = ip_hdr(skb); |
| h = skb->data; |
| flags = *(__be16*)h; |
| |
| if (flags&(GRE_CSUM|GRE_KEY|GRE_ROUTING|GRE_SEQ|GRE_VERSION)) { |
| /* - Version must be 0. |
| - We do not support routing headers. |
| */ |
| if (flags&(GRE_VERSION|GRE_ROUTING)) |
| goto drop_nolock; |
| |
| if (flags&GRE_CSUM) { |
| switch (skb->ip_summed) { |
| case CHECKSUM_COMPLETE: |
| csum = csum_fold(skb->csum); |
| if (!csum) |
| break; |
| /* fall through */ |
| case CHECKSUM_NONE: |
| skb->csum = 0; |
| csum = __skb_checksum_complete(skb); |
| skb->ip_summed = CHECKSUM_COMPLETE; |
| } |
| offset += 4; |
| } |
| if (flags&GRE_KEY) { |
| key = *(__be32*)(h + offset); |
| offset += 4; |
| } |
| if (flags&GRE_SEQ) { |
| seqno = ntohl(*(__be32*)(h + offset)); |
| offset += 4; |
| } |
| } |
| |
| read_lock(&ipgre_lock); |
| if ((tunnel = ipgre_tunnel_lookup(iph->saddr, iph->daddr, key)) != NULL) { |
| secpath_reset(skb); |
| |
| skb->protocol = *(__be16*)(h + 2); |
| /* WCCP version 1 and 2 protocol decoding. |
| * - Change protocol to IP |
| * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header |
| */ |
| if (flags == 0 && |
| skb->protocol == htons(ETH_P_WCCP)) { |
| skb->protocol = htons(ETH_P_IP); |
| if ((*(h + offset) & 0xF0) != 0x40) |
| offset += 4; |
| } |
| |
| skb->mac_header = skb->network_header; |
| __pskb_pull(skb, offset); |
| skb_reset_network_header(skb); |
| skb_postpull_rcsum(skb, skb_transport_header(skb), offset); |
| skb->pkt_type = PACKET_HOST; |
| #ifdef CONFIG_NET_IPGRE_BROADCAST |
| if (ipv4_is_multicast(iph->daddr)) { |
| /* Looped back packet, drop it! */ |
| if (((struct rtable*)skb->dst)->fl.iif == 0) |
| goto drop; |
| tunnel->stat.multicast++; |
| skb->pkt_type = PACKET_BROADCAST; |
| } |
| #endif |
| |
| if (((flags&GRE_CSUM) && csum) || |
| (!(flags&GRE_CSUM) && tunnel->parms.i_flags&GRE_CSUM)) { |
| tunnel->stat.rx_crc_errors++; |
| tunnel->stat.rx_errors++; |
| goto drop; |
| } |
| if (tunnel->parms.i_flags&GRE_SEQ) { |
| if (!(flags&GRE_SEQ) || |
| (tunnel->i_seqno && (s32)(seqno - tunnel->i_seqno) < 0)) { |
| tunnel->stat.rx_fifo_errors++; |
| tunnel->stat.rx_errors++; |
| goto drop; |
| } |
| tunnel->i_seqno = seqno + 1; |
| } |
| tunnel->stat.rx_packets++; |
| tunnel->stat.rx_bytes += skb->len; |
| skb->dev = tunnel->dev; |
| dst_release(skb->dst); |
| skb->dst = NULL; |
| nf_reset(skb); |
| ipgre_ecn_decapsulate(iph, skb); |
| netif_rx(skb); |
| read_unlock(&ipgre_lock); |
| return(0); |
| } |
| icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); |
| |
| drop: |
| read_unlock(&ipgre_lock); |
| drop_nolock: |
| kfree_skb(skb); |
| return(0); |
| } |
| |
| static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev) |
| { |
| struct ip_tunnel *tunnel = netdev_priv(dev); |
| struct net_device_stats *stats = &tunnel->stat; |
| struct iphdr *old_iph = ip_hdr(skb); |
| struct iphdr *tiph; |
| u8 tos; |
| __be16 df; |
| struct rtable *rt; /* Route to the other host */ |
| struct net_device *tdev; /* Device to other host */ |
| struct iphdr *iph; /* Our new IP header */ |
| unsigned int max_headroom; /* The extra header space needed */ |
| int gre_hlen; |
| __be32 dst; |
| int mtu; |
| |
| if (tunnel->recursion++) { |
| tunnel->stat.collisions++; |
| goto tx_error; |
| } |
| |
| if (dev->header_ops) { |
| gre_hlen = 0; |
| tiph = (struct iphdr*)skb->data; |
| } else { |
| gre_hlen = tunnel->hlen; |
| tiph = &tunnel->parms.iph; |
| } |
| |
| if ((dst = tiph->daddr) == 0) { |
| /* NBMA tunnel */ |
| |
| if (skb->dst == NULL) { |
| tunnel->stat.tx_fifo_errors++; |
| goto tx_error; |
| } |
| |
| if (skb->protocol == htons(ETH_P_IP)) { |
| rt = (struct rtable*)skb->dst; |
| if ((dst = rt->rt_gateway) == 0) |
| goto tx_error_icmp; |
| } |
| #ifdef CONFIG_IPV6 |
| else if (skb->protocol == htons(ETH_P_IPV6)) { |
| struct in6_addr *addr6; |
| int addr_type; |
| struct neighbour *neigh = skb->dst->neighbour; |
| |
| if (neigh == NULL) |
| goto tx_error; |
| |
| addr6 = (struct in6_addr*)&neigh->primary_key; |
| addr_type = ipv6_addr_type(addr6); |
| |
| if (addr_type == IPV6_ADDR_ANY) { |
| addr6 = &ipv6_hdr(skb)->daddr; |
| addr_type = ipv6_addr_type(addr6); |
| } |
| |
| if ((addr_type & IPV6_ADDR_COMPATv4) == 0) |
| goto tx_error_icmp; |
| |
| dst = addr6->s6_addr32[3]; |
| } |
| #endif |
| else |
| goto tx_error; |
| } |
| |
| tos = tiph->tos; |
| if (tos&1) { |
| if (skb->protocol == htons(ETH_P_IP)) |
| tos = old_iph->tos; |
| tos &= ~1; |
| } |
| |
| { |
| struct flowi fl = { .oif = tunnel->parms.link, |
| .nl_u = { .ip4_u = |
| { .daddr = dst, |
| .saddr = tiph->saddr, |
| .tos = RT_TOS(tos) } }, |
| .proto = IPPROTO_GRE }; |
| if (ip_route_output_key(&init_net, &rt, &fl)) { |
| tunnel->stat.tx_carrier_errors++; |
| goto tx_error; |
| } |
| } |
| tdev = rt->u.dst.dev; |
| |
| if (tdev == dev) { |
| ip_rt_put(rt); |
| tunnel->stat.collisions++; |
| goto tx_error; |
| } |
| |
| df = tiph->frag_off; |
| if (df) |
| mtu = dst_mtu(&rt->u.dst) - tunnel->hlen; |
| else |
| mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu; |
| |
| if (skb->dst) |
| skb->dst->ops->update_pmtu(skb->dst, mtu); |
| |
| if (skb->protocol == htons(ETH_P_IP)) { |
| df |= (old_iph->frag_off&htons(IP_DF)); |
| |
| if ((old_iph->frag_off&htons(IP_DF)) && |
| mtu < ntohs(old_iph->tot_len)) { |
| icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); |
| ip_rt_put(rt); |
| goto tx_error; |
| } |
| } |
| #ifdef CONFIG_IPV6 |
| else if (skb->protocol == htons(ETH_P_IPV6)) { |
| struct rt6_info *rt6 = (struct rt6_info*)skb->dst; |
| |
| if (rt6 && mtu < dst_mtu(skb->dst) && mtu >= IPV6_MIN_MTU) { |
| if ((tunnel->parms.iph.daddr && |
| !ipv4_is_multicast(tunnel->parms.iph.daddr)) || |
| rt6->rt6i_dst.plen == 128) { |
| rt6->rt6i_flags |= RTF_MODIFIED; |
| skb->dst->metrics[RTAX_MTU-1] = mtu; |
| } |
| } |
| |
| if (mtu >= IPV6_MIN_MTU && mtu < skb->len - tunnel->hlen + gre_hlen) { |
| icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev); |
| ip_rt_put(rt); |
| goto tx_error; |
| } |
| } |
| #endif |
| |
| if (tunnel->err_count > 0) { |
| if (jiffies - tunnel->err_time < IPTUNNEL_ERR_TIMEO) { |
| tunnel->err_count--; |
| |
| dst_link_failure(skb); |
| } else |
| tunnel->err_count = 0; |
| } |
| |
| max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen; |
| |
| if (skb_headroom(skb) < max_headroom || skb_shared(skb)|| |
| (skb_cloned(skb) && !skb_clone_writable(skb, 0))) { |
| struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom); |
| if (!new_skb) { |
| ip_rt_put(rt); |
| stats->tx_dropped++; |
| dev_kfree_skb(skb); |
| tunnel->recursion--; |
| return 0; |
| } |
| if (skb->sk) |
| skb_set_owner_w(new_skb, skb->sk); |
| dev_kfree_skb(skb); |
| skb = new_skb; |
| old_iph = ip_hdr(skb); |
| } |
| |
| skb->transport_header = skb->network_header; |
| skb_push(skb, gre_hlen); |
| skb_reset_network_header(skb); |
| memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); |
| IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | |
| IPSKB_REROUTED); |
| dst_release(skb->dst); |
| skb->dst = &rt->u.dst; |
| |
| /* |
| * Push down and install the IPIP header. |
| */ |
| |
| iph = ip_hdr(skb); |
| iph->version = 4; |
| iph->ihl = sizeof(struct iphdr) >> 2; |
| iph->frag_off = df; |
| iph->protocol = IPPROTO_GRE; |
| iph->tos = ipgre_ecn_encapsulate(tos, old_iph, skb); |
| iph->daddr = rt->rt_dst; |
| iph->saddr = rt->rt_src; |
| |
| if ((iph->ttl = tiph->ttl) == 0) { |
| if (skb->protocol == htons(ETH_P_IP)) |
| iph->ttl = old_iph->ttl; |
| #ifdef CONFIG_IPV6 |
| else if (skb->protocol == htons(ETH_P_IPV6)) |
| iph->ttl = ((struct ipv6hdr*)old_iph)->hop_limit; |
| #endif |
| else |
| iph->ttl = dst_metric(&rt->u.dst, RTAX_HOPLIMIT); |
| } |
| |
| ((__be16*)(iph+1))[0] = tunnel->parms.o_flags; |
| ((__be16*)(iph+1))[1] = skb->protocol; |
| |
| if (tunnel->parms.o_flags&(GRE_KEY|GRE_CSUM|GRE_SEQ)) { |
| __be32 *ptr = (__be32*)(((u8*)iph) + tunnel->hlen - 4); |
| |
| if (tunnel->parms.o_flags&GRE_SEQ) { |
| ++tunnel->o_seqno; |
| *ptr = htonl(tunnel->o_seqno); |
| ptr--; |
| } |
| if (tunnel->parms.o_flags&GRE_KEY) { |
| *ptr = tunnel->parms.o_key; |
| ptr--; |
| } |
| if (tunnel->parms.o_flags&GRE_CSUM) { |
| *ptr = 0; |
| *(__sum16*)ptr = ip_compute_csum((void*)(iph+1), skb->len - sizeof(struct iphdr)); |
| } |
| } |
| |
| nf_reset(skb); |
| |
| IPTUNNEL_XMIT(); |
| tunnel->recursion--; |
| return 0; |
| |
| tx_error_icmp: |
| dst_link_failure(skb); |
| |
| tx_error: |
| stats->tx_errors++; |
| dev_kfree_skb(skb); |
| tunnel->recursion--; |
| return 0; |
| } |
| |
| static void ipgre_tunnel_bind_dev(struct net_device *dev) |
| { |
| struct net_device *tdev = NULL; |
| struct ip_tunnel *tunnel; |
| struct iphdr *iph; |
| int hlen = LL_MAX_HEADER; |
| int mtu = ETH_DATA_LEN; |
| int addend = sizeof(struct iphdr) + 4; |
| |
| tunnel = netdev_priv(dev); |
| iph = &tunnel->parms.iph; |
| |
| /* Guess output device to choose reasonable mtu and hard_header_len */ |
| |
| if (iph->daddr) { |
| struct flowi fl = { .oif = tunnel->parms.link, |
| .nl_u = { .ip4_u = |
| { .daddr = iph->daddr, |
| .saddr = iph->saddr, |
| .tos = RT_TOS(iph->tos) } }, |
| .proto = IPPROTO_GRE }; |
| struct rtable *rt; |
| if (!ip_route_output_key(&init_net, &rt, &fl)) { |
| tdev = rt->u.dst.dev; |
| ip_rt_put(rt); |
| } |
| dev->flags |= IFF_POINTOPOINT; |
| } |
| |
| if (!tdev && tunnel->parms.link) |
| tdev = __dev_get_by_index(&init_net, tunnel->parms.link); |
| |
| if (tdev) { |
| hlen = tdev->hard_header_len; |
| mtu = tdev->mtu; |
| } |
| dev->iflink = tunnel->parms.link; |
| |
| /* Precalculate GRE options length */ |
| if (tunnel->parms.o_flags&(GRE_CSUM|GRE_KEY|GRE_SEQ)) { |
| if (tunnel->parms.o_flags&GRE_CSUM) |
| addend += 4; |
| if (tunnel->parms.o_flags&GRE_KEY) |
| addend += 4; |
| if (tunnel->parms.o_flags&GRE_SEQ) |
| addend += 4; |
| } |
| dev->hard_header_len = hlen + addend; |
| dev->mtu = mtu - addend; |
| tunnel->hlen = addend; |
| |
| } |
| |
| static int |
| ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd) |
| { |
| int err = 0; |
| struct ip_tunnel_parm p; |
| struct ip_tunnel *t; |
| |
| switch (cmd) { |
| case SIOCGETTUNNEL: |
| t = NULL; |
| if (dev == ipgre_fb_tunnel_dev) { |
| if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) { |
| err = -EFAULT; |
| break; |
| } |
| t = ipgre_tunnel_locate(&p, 0); |
| } |
| if (t == NULL) |
| t = netdev_priv(dev); |
| memcpy(&p, &t->parms, sizeof(p)); |
| if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p))) |
| err = -EFAULT; |
| break; |
| |
| case SIOCADDTUNNEL: |
| case SIOCCHGTUNNEL: |
| err = -EPERM; |
| if (!capable(CAP_NET_ADMIN)) |
| goto done; |
| |
| err = -EFAULT; |
| if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) |
| goto done; |
| |
| err = -EINVAL; |
| if (p.iph.version != 4 || p.iph.protocol != IPPROTO_GRE || |
| p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)) || |
| ((p.i_flags|p.o_flags)&(GRE_VERSION|GRE_ROUTING))) |
| goto done; |
| if (p.iph.ttl) |
| p.iph.frag_off |= htons(IP_DF); |
| |
| if (!(p.i_flags&GRE_KEY)) |
| p.i_key = 0; |
| if (!(p.o_flags&GRE_KEY)) |
| p.o_key = 0; |
| |
| t = ipgre_tunnel_locate(&p, cmd == SIOCADDTUNNEL); |
| |
| if (dev != ipgre_fb_tunnel_dev && cmd == SIOCCHGTUNNEL) { |
| if (t != NULL) { |
| if (t->dev != dev) { |
| err = -EEXIST; |
| break; |
| } |
| } else { |
| unsigned nflags=0; |
| |
| t = netdev_priv(dev); |
| |
| if (ipv4_is_multicast(p.iph.daddr)) |
| nflags = IFF_BROADCAST; |
| else if (p.iph.daddr) |
| nflags = IFF_POINTOPOINT; |
| |
| if ((dev->flags^nflags)&(IFF_POINTOPOINT|IFF_BROADCAST)) { |
| err = -EINVAL; |
| break; |
| } |
| ipgre_tunnel_unlink(t); |
| t->parms.iph.saddr = p.iph.saddr; |
| t->parms.iph.daddr = p.iph.daddr; |
| t->parms.i_key = p.i_key; |
| t->parms.o_key = p.o_key; |
| memcpy(dev->dev_addr, &p.iph.saddr, 4); |
| memcpy(dev->broadcast, &p.iph.daddr, 4); |
| ipgre_tunnel_link(t); |
| netdev_state_change(dev); |
| } |
| } |
| |
| if (t) { |
| err = 0; |
| if (cmd == SIOCCHGTUNNEL) { |
| t->parms.iph.ttl = p.iph.ttl; |
| t->parms.iph.tos = p.iph.tos; |
| t->parms.iph.frag_off = p.iph.frag_off; |
| if (t->parms.link != p.link) { |
| t->parms.link = p.link; |
| ipgre_tunnel_bind_dev(dev); |
| netdev_state_change(dev); |
| } |
| } |
| if (copy_to_user(ifr->ifr_ifru.ifru_data, &t->parms, sizeof(p))) |
| err = -EFAULT; |
| } else |
| err = (cmd == SIOCADDTUNNEL ? -ENOBUFS : -ENOENT); |
| break; |
| |
| case SIOCDELTUNNEL: |
| err = -EPERM; |
| if (!capable(CAP_NET_ADMIN)) |
| goto done; |
| |
| if (dev == ipgre_fb_tunnel_dev) { |
| err = -EFAULT; |
| if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) |
| goto done; |
| err = -ENOENT; |
| if ((t = ipgre_tunnel_locate(&p, 0)) == NULL) |
| goto done; |
| err = -EPERM; |
| if (t == netdev_priv(ipgre_fb_tunnel_dev)) |
| goto done; |
| dev = t->dev; |
| } |
| unregister_netdevice(dev); |
| err = 0; |
| break; |
| |
| default: |
| err = -EINVAL; |
| } |
| |
| done: |
| return err; |
| } |
| |
| static struct net_device_stats *ipgre_tunnel_get_stats(struct net_device *dev) |
| { |
| return &(((struct ip_tunnel*)netdev_priv(dev))->stat); |
| } |
| |
| static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu) |
| { |
| struct ip_tunnel *tunnel = netdev_priv(dev); |
| if (new_mtu < 68 || new_mtu > 0xFFF8 - tunnel->hlen) |
| return -EINVAL; |
| dev->mtu = new_mtu; |
| return 0; |
| } |
| |
| /* Nice toy. Unfortunately, useless in real life :-) |
| It allows to construct virtual multiprotocol broadcast "LAN" |
| over the Internet, provided multicast routing is tuned. |
| |
| |
| I have no idea was this bicycle invented before me, |
| so that I had to set ARPHRD_IPGRE to a random value. |
| I have an impression, that Cisco could make something similar, |
| but this feature is apparently missing in IOS<=11.2(8). |
| |
| I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks |
| with broadcast 224.66.66.66. If you have access to mbone, play with me :-) |
| |
| ping -t 255 224.66.66.66 |
| |
| If nobody answers, mbone does not work. |
| |
| ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255 |
| ip addr add 10.66.66.<somewhat>/24 dev Universe |
| ifconfig Universe up |
| ifconfig Universe add fe80::<Your_real_addr>/10 |
| ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96 |
| ftp 10.66.66.66 |
| ... |
| ftp fec0:6666:6666::193.233.7.65 |
| ... |
| |
| */ |
| |
| static int ipgre_header(struct sk_buff *skb, struct net_device *dev, |
| unsigned short type, |
| const void *daddr, const void *saddr, unsigned len) |
| { |
| struct ip_tunnel *t = netdev_priv(dev); |
| struct iphdr *iph = (struct iphdr *)skb_push(skb, t->hlen); |
| __be16 *p = (__be16*)(iph+1); |
| |
| memcpy(iph, &t->parms.iph, sizeof(struct iphdr)); |
| p[0] = t->parms.o_flags; |
| p[1] = htons(type); |
| |
| /* |
| * Set the source hardware address. |
| */ |
| |
| if (saddr) |
| memcpy(&iph->saddr, saddr, 4); |
| |
| if (daddr) { |
| memcpy(&iph->daddr, daddr, 4); |
| return t->hlen; |
| } |
| if (iph->daddr && !ipv4_is_multicast(iph->daddr)) |
| return t->hlen; |
| |
| return -t->hlen; |
| } |
| |
| static int ipgre_header_parse(const struct sk_buff *skb, unsigned char *haddr) |
| { |
| struct iphdr *iph = (struct iphdr*) skb_mac_header(skb); |
| memcpy(haddr, &iph->saddr, 4); |
| return 4; |
| } |
| |
| static const struct header_ops ipgre_header_ops = { |
| .create = ipgre_header, |
| .parse = ipgre_header_parse, |
| }; |
| |
| #ifdef CONFIG_NET_IPGRE_BROADCAST |
| static int ipgre_open(struct net_device *dev) |
| { |
| struct ip_tunnel *t = netdev_priv(dev); |
| |
| if (ipv4_is_multicast(t->parms.iph.daddr)) { |
| struct flowi fl = { .oif = t->parms.link, |
| .nl_u = { .ip4_u = |
| { .daddr = t->parms.iph.daddr, |
| .saddr = t->parms.iph.saddr, |
| .tos = RT_TOS(t->parms.iph.tos) } }, |
| .proto = IPPROTO_GRE }; |
| struct rtable *rt; |
| if (ip_route_output_key(&init_net, &rt, &fl)) |
| return -EADDRNOTAVAIL; |
| dev = rt->u.dst.dev; |
| ip_rt_put(rt); |
| if (__in_dev_get_rtnl(dev) == NULL) |
| return -EADDRNOTAVAIL; |
| t->mlink = dev->ifindex; |
| ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr); |
| } |
| return 0; |
| } |
| |
| static int ipgre_close(struct net_device *dev) |
| { |
| struct ip_tunnel *t = netdev_priv(dev); |
| if (ipv4_is_multicast(t->parms.iph.daddr) && t->mlink) { |
| struct in_device *in_dev; |
| in_dev = inetdev_by_index(dev->nd_net, t->mlink); |
| if (in_dev) { |
| ip_mc_dec_group(in_dev, t->parms.iph.daddr); |
| in_dev_put(in_dev); |
| } |
| } |
| return 0; |
| } |
| |
| #endif |
| |
| static void ipgre_tunnel_setup(struct net_device *dev) |
| { |
| dev->uninit = ipgre_tunnel_uninit; |
| dev->destructor = free_netdev; |
| dev->hard_start_xmit = ipgre_tunnel_xmit; |
| dev->get_stats = ipgre_tunnel_get_stats; |
| dev->do_ioctl = ipgre_tunnel_ioctl; |
| dev->change_mtu = ipgre_tunnel_change_mtu; |
| |
| dev->type = ARPHRD_IPGRE; |
| dev->hard_header_len = LL_MAX_HEADER + sizeof(struct iphdr) + 4; |
| dev->mtu = ETH_DATA_LEN - sizeof(struct iphdr) - 4; |
| dev->flags = IFF_NOARP; |
| dev->iflink = 0; |
| dev->addr_len = 4; |
| } |
| |
| static int ipgre_tunnel_init(struct net_device *dev) |
| { |
| struct ip_tunnel *tunnel; |
| struct iphdr *iph; |
| |
| tunnel = netdev_priv(dev); |
| iph = &tunnel->parms.iph; |
| |
| tunnel->dev = dev; |
| strcpy(tunnel->parms.name, dev->name); |
| |
| memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4); |
| memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4); |
| |
| ipgre_tunnel_bind_dev(dev); |
| |
| if (iph->daddr) { |
| #ifdef CONFIG_NET_IPGRE_BROADCAST |
| if (ipv4_is_multicast(iph->daddr)) { |
| if (!iph->saddr) |
| return -EINVAL; |
| dev->flags = IFF_BROADCAST; |
| dev->header_ops = &ipgre_header_ops; |
| dev->open = ipgre_open; |
| dev->stop = ipgre_close; |
| } |
| #endif |
| } else |
| dev->header_ops = &ipgre_header_ops; |
| |
| return 0; |
| } |
| |
| static int __init ipgre_fb_tunnel_init(struct net_device *dev) |
| { |
| struct ip_tunnel *tunnel = netdev_priv(dev); |
| struct iphdr *iph = &tunnel->parms.iph; |
| |
| tunnel->dev = dev; |
| strcpy(tunnel->parms.name, dev->name); |
| |
| iph->version = 4; |
| iph->protocol = IPPROTO_GRE; |
| iph->ihl = 5; |
| tunnel->hlen = sizeof(struct iphdr) + 4; |
| |
| dev_hold(dev); |
| tunnels_wc[0] = tunnel; |
| return 0; |
| } |
| |
| |
| static struct net_protocol ipgre_protocol = { |
| .handler = ipgre_rcv, |
| .err_handler = ipgre_err, |
| }; |
| |
| |
| /* |
| * And now the modules code and kernel interface. |
| */ |
| |
| static int __init ipgre_init(void) |
| { |
| int err; |
| |
| printk(KERN_INFO "GRE over IPv4 tunneling driver\n"); |
| |
| if (inet_add_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) { |
| printk(KERN_INFO "ipgre init: can't add protocol\n"); |
| return -EAGAIN; |
| } |
| |
| ipgre_fb_tunnel_dev = alloc_netdev(sizeof(struct ip_tunnel), "gre0", |
| ipgre_tunnel_setup); |
| if (!ipgre_fb_tunnel_dev) { |
| err = -ENOMEM; |
| goto err1; |
| } |
| |
| ipgre_fb_tunnel_dev->init = ipgre_fb_tunnel_init; |
| |
| if ((err = register_netdev(ipgre_fb_tunnel_dev))) |
| goto err2; |
| out: |
| return err; |
| err2: |
| free_netdev(ipgre_fb_tunnel_dev); |
| err1: |
| inet_del_protocol(&ipgre_protocol, IPPROTO_GRE); |
| goto out; |
| } |
| |
| static void __exit ipgre_destroy_tunnels(void) |
| { |
| int prio; |
| |
| for (prio = 0; prio < 4; prio++) { |
| int h; |
| for (h = 0; h < HASH_SIZE; h++) { |
| struct ip_tunnel *t; |
| while ((t = tunnels[prio][h]) != NULL) |
| unregister_netdevice(t->dev); |
| } |
| } |
| } |
| |
| static void __exit ipgre_fini(void) |
| { |
| if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) |
| printk(KERN_INFO "ipgre close: can't remove protocol\n"); |
| |
| rtnl_lock(); |
| ipgre_destroy_tunnels(); |
| rtnl_unlock(); |
| } |
| |
| module_init(ipgre_init); |
| module_exit(ipgre_fini); |
| MODULE_LICENSE("GPL"); |