![Nicolas Dichtel](/assets/img/avatar_default.png)
By default, DSCP is copying during encapsulation. Copying the DSCP in IPsec tunneling may be a bit dangerous because packets with different DSCP may get reordered relative to each other in the network and then dropped by the remote IPsec GW if the reordering becomes too big compared to the replay window. It is possible to avoid this copy with netfilter rules, but it's very convenient to be able to configure it for each SA directly. This patch adds a toogle for this purpose. By default, it's not set to maintain backward compatibility. Field flags in struct xfrm_usersa_info is full, hence I add a new attribute. Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
194 lines
4.6 KiB
C
194 lines
4.6 KiB
C
/*
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* xfrm4_mode_tunnel.c - Tunnel mode encapsulation for IPv4.
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*
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* Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
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*/
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#include <linux/gfp.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/stringify.h>
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#include <net/dst.h>
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#include <net/inet_ecn.h>
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#include <net/ip.h>
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#include <net/xfrm.h>
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/* Informational hook. The decap is still done here. */
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static struct xfrm_tunnel __rcu *rcv_notify_handlers __read_mostly;
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static DEFINE_MUTEX(xfrm4_mode_tunnel_input_mutex);
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int xfrm4_mode_tunnel_input_register(struct xfrm_tunnel *handler)
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{
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struct xfrm_tunnel __rcu **pprev;
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struct xfrm_tunnel *t;
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int ret = -EEXIST;
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int priority = handler->priority;
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mutex_lock(&xfrm4_mode_tunnel_input_mutex);
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for (pprev = &rcv_notify_handlers;
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(t = rcu_dereference_protected(*pprev,
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lockdep_is_held(&xfrm4_mode_tunnel_input_mutex))) != NULL;
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pprev = &t->next) {
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if (t->priority > priority)
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break;
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if (t->priority == priority)
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goto err;
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}
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handler->next = *pprev;
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rcu_assign_pointer(*pprev, handler);
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ret = 0;
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err:
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mutex_unlock(&xfrm4_mode_tunnel_input_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(xfrm4_mode_tunnel_input_register);
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int xfrm4_mode_tunnel_input_deregister(struct xfrm_tunnel *handler)
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{
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struct xfrm_tunnel __rcu **pprev;
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struct xfrm_tunnel *t;
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int ret = -ENOENT;
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mutex_lock(&xfrm4_mode_tunnel_input_mutex);
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for (pprev = &rcv_notify_handlers;
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(t = rcu_dereference_protected(*pprev,
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lockdep_is_held(&xfrm4_mode_tunnel_input_mutex))) != NULL;
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pprev = &t->next) {
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if (t == handler) {
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*pprev = handler->next;
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ret = 0;
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break;
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}
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}
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mutex_unlock(&xfrm4_mode_tunnel_input_mutex);
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synchronize_net();
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return ret;
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}
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EXPORT_SYMBOL_GPL(xfrm4_mode_tunnel_input_deregister);
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static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
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{
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struct iphdr *inner_iph = ipip_hdr(skb);
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if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos))
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IP_ECN_set_ce(inner_iph);
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}
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/* Add encapsulation header.
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*
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* The top IP header will be constructed per RFC 2401.
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*/
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static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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struct dst_entry *dst = skb_dst(skb);
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struct iphdr *top_iph;
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int flags;
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skb_set_network_header(skb, -x->props.header_len);
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skb->mac_header = skb->network_header +
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offsetof(struct iphdr, protocol);
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skb->transport_header = skb->network_header + sizeof(*top_iph);
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top_iph = ip_hdr(skb);
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top_iph->ihl = 5;
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top_iph->version = 4;
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top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
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/* DS disclosing depends on XFRM_SA_XFLAG_DONT_ENCAP_DSCP */
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if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
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top_iph->tos = 0;
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else
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top_iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
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top_iph->tos = INET_ECN_encapsulate(top_iph->tos,
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XFRM_MODE_SKB_CB(skb)->tos);
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flags = x->props.flags;
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if (flags & XFRM_STATE_NOECN)
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IP_ECN_clear(top_iph);
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top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
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0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
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ip_select_ident(top_iph, dst->child, NULL);
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top_iph->ttl = ip4_dst_hoplimit(dst->child);
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top_iph->saddr = x->props.saddr.a4;
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top_iph->daddr = x->id.daddr.a4;
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return 0;
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}
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#define for_each_input_rcu(head, handler) \
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for (handler = rcu_dereference(head); \
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handler != NULL; \
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handler = rcu_dereference(handler->next))
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static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
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{
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struct xfrm_tunnel *handler;
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int err = -EINVAL;
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if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP)
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goto out;
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if (!pskb_may_pull(skb, sizeof(struct iphdr)))
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goto out;
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for_each_input_rcu(rcv_notify_handlers, handler)
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handler->handler(skb);
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err = skb_unclone(skb, GFP_ATOMIC);
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if (err)
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goto out;
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if (x->props.flags & XFRM_STATE_DECAP_DSCP)
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ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb));
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if (!(x->props.flags & XFRM_STATE_NOECN))
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ipip_ecn_decapsulate(skb);
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skb_reset_network_header(skb);
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skb_mac_header_rebuild(skb);
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err = 0;
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out:
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return err;
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}
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static struct xfrm_mode xfrm4_tunnel_mode = {
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.input2 = xfrm4_mode_tunnel_input,
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.input = xfrm_prepare_input,
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.output2 = xfrm4_mode_tunnel_output,
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.output = xfrm4_prepare_output,
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.owner = THIS_MODULE,
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.encap = XFRM_MODE_TUNNEL,
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.flags = XFRM_MODE_FLAG_TUNNEL,
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};
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static int __init xfrm4_mode_tunnel_init(void)
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{
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return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
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}
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static void __exit xfrm4_mode_tunnel_exit(void)
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{
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int err;
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err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
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BUG_ON(err);
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}
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module_init(xfrm4_mode_tunnel_init);
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module_exit(xfrm4_mode_tunnel_exit);
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);
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