// SPDX-License-Identifier: GPL-2.0-or-later /* * Linux NET3: IP/IP protocol decoder. * * Authors: * Sam Lantinga ([email protected]) 02/01/95 * * Fixes: * Alan Cox : Merged and made usable non modular (its so tiny its silly as * a module taking up 2 pages). * Alan Cox : Fixed bug with 1.3.18 and IPIP not working (now needs to set skb->h.iph) * to keep ip_forward happy. * Alan Cox : More fixes for 1.3.21, and firewall fix. Maybe this will work soon 8). * Kai Schulte : Fixed #defines for IP_FIREWALL->FIREWALL * David Woodhouse : Perform some basic ICMP handling. * IPIP Routing without decapsulation. * Carlos Picoto : GRE over IP support * Alexey Kuznetsov: Reworked. Really, now it is truncated version of ipv4/ip_gre.c. * I do not want to merge them together. */ /* tunnel.c: an IP tunnel driver The purpose of this driver is to provide an IP tunnel through which you can tunnel network traffic transparently across subnets. This was written by looking at Nick Holloway's dummy driver Thanks for the great code! -Sam Lantinga ([email protected]) 02/01/95 Minor tweaks: Cleaned up the code a little and added some pre-1.3.0 tweaks. dev->hard_header/hard_header_len changed to use no headers. Comments/bracketing tweaked. Made the tunnels use dev->name not tunnel: when error reporting. Added tx_dropped stat -Alan Cox ([email protected]) 21 March 95 Reworked: Changed to tunnel to destination gateway in addition to the tunnel's pointopoint address Almost completely rewritten Note: There is currently no firewall or ICMP handling done. -Sam Lantinga ([email protected]) 02/13/96 */ /* Things I wish I had known when writing the tunnel driver: When the tunnel_xmit() function is called, the skb contains the packet to be sent (plus a great deal of extra info), and dev contains the tunnel device that _we_ are. When we are passed a packet, we are expected to fill in the source address with our source IP address. What is the proper way to allocate, copy and free a buffer? After you allocate it, it is a "0 length" chunk of memory starting at zero. If you want to add headers to the buffer later, you'll have to call "skb_reserve(skb, amount)" with the amount of memory you want reserved. Then, you call "skb_put(skb, amount)" with the amount of space you want in the buffer. skb_put() returns a pointer to the top (#0) of that buffer. skb->len is set to the amount of space you have "allocated" with skb_put(). You can then write up to skb->len bytes to that buffer. If you need more, you can call skb_put() again with the additional amount of space you need. You can find out how much more space you can allocate by calling "skb_tailroom(skb)". Now, to add header space, call "skb_push(skb, header_len)". This creates space at the beginning of the buffer and returns a pointer to this new space. If later you need to strip a header from a buffer, call "skb_pull(skb, header_len)". skb_headroom() will return how much space is left at the top of the buffer (before the main data). Remember, this headroom space must be reserved before the skb_put() function is called. */ /* This version of net/ipv4/ipip.c is cloned of net/ipv4/ip_gre.c For comments look at net/ipv4/ip_gre.c --ANK */ #include <linux/capability.h> #include <linux/module.h> #include <linux/types.h> #include <linux/kernel.h> #include <linux/slab.h> #include <linux/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/init.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/ip_tunnels.h> #include <net/inet_ecn.h> #include <net/xfrm.h> #include <net/net_namespace.h> #include <net/netns/generic.h> #include <net/dst_metadata.h> static bool log_ecn_error = …; module_param(log_ecn_error, bool, 0644); MODULE_PARM_DESC(…) …; static unsigned int ipip_net_id __read_mostly; static int ipip_tunnel_init(struct net_device *dev); static struct rtnl_link_ops ipip_link_ops __read_mostly; static int ipip_err(struct sk_buff *skb, u32 info) { … } static const struct tnl_ptk_info ipip_tpi = …; #if IS_ENABLED(CONFIG_MPLS) static const struct tnl_ptk_info mplsip_tpi = …; #endif static int ipip_tunnel_rcv(struct sk_buff *skb, u8 ipproto) { … } static int ipip_rcv(struct sk_buff *skb) { … } #if IS_ENABLED(CONFIG_MPLS) static int mplsip_rcv(struct sk_buff *skb) { … } #endif /* * This function assumes it is being called from dev_queue_xmit() * and that skb is filled properly by that function. */ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev) { … } static bool ipip_tunnel_ioctl_verify_protocol(u8 ipproto) { … } static int ipip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p, int cmd) { … } static const struct net_device_ops ipip_netdev_ops = …; #define IPIP_FEATURES … static void ipip_tunnel_setup(struct net_device *dev) { … } static int ipip_tunnel_init(struct net_device *dev) { … } static int ipip_tunnel_validate(struct nlattr *tb[], struct nlattr *data[], struct netlink_ext_ack *extack) { … } static void ipip_netlink_parms(struct nlattr *data[], struct ip_tunnel_parm_kern *parms, bool *collect_md, __u32 *fwmark) { … } static int ipip_newlink(struct net *src_net, struct net_device *dev, struct nlattr *tb[], struct nlattr *data[], struct netlink_ext_ack *extack) { … } static int ipip_changelink(struct net_device *dev, struct nlattr *tb[], struct nlattr *data[], struct netlink_ext_ack *extack) { … } static size_t ipip_get_size(const struct net_device *dev) { … } static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev) { … } static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = …; static struct rtnl_link_ops ipip_link_ops __read_mostly = …; static struct xfrm_tunnel ipip_handler __read_mostly = …; #if IS_ENABLED(CONFIG_MPLS) static struct xfrm_tunnel mplsip_handler __read_mostly = …; #endif static int __net_init ipip_init_net(struct net *net) { … } static void __net_exit ipip_exit_batch_rtnl(struct list_head *list_net, struct list_head *dev_to_kill) { … } static struct pernet_operations ipip_net_ops = …; static int __init ipip_init(void) { … } static void __exit ipip_fini(void) { … } module_init(…) …; module_exit(ipip_fini); MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; MODULE_ALIAS_RTNL_LINK(…) …; MODULE_ALIAS_NETDEV(…) …;
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