502 lines
10 KiB
C
502 lines
10 KiB
C
/*
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* IP Payload Compression Protocol (IPComp) - RFC3173.
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*
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* Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* Todo:
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* - Tunable compression parameters.
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* - Compression stats.
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* - Adaptive compression.
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*/
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#include <linux/module.h>
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#include <asm/scatterlist.h>
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#include <asm/semaphore.h>
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#include <linux/crypto.h>
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#include <linux/pfkeyv2.h>
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#include <linux/percpu.h>
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#include <linux/smp.h>
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#include <linux/list.h>
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#include <linux/vmalloc.h>
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#include <linux/rtnetlink.h>
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#include <linux/mutex.h>
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#include <net/ip.h>
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#include <net/xfrm.h>
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#include <net/icmp.h>
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#include <net/ipcomp.h>
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#include <net/protocol.h>
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struct ipcomp_tfms {
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struct list_head list;
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struct crypto_comp **tfms;
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int users;
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};
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static DEFINE_MUTEX(ipcomp_resource_mutex);
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static void **ipcomp_scratches;
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static int ipcomp_scratch_users;
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static LIST_HEAD(ipcomp_tfms_list);
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static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err, plen, dlen;
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struct ipcomp_data *ipcd = x->data;
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u8 *start, *scratch;
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struct crypto_comp *tfm;
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int cpu;
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plen = skb->len;
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dlen = IPCOMP_SCRATCH_SIZE;
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start = skb->data;
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cpu = get_cpu();
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scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
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tfm = *per_cpu_ptr(ipcd->tfms, cpu);
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err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
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if (err)
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goto out;
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if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
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err = -EINVAL;
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goto out;
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}
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err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
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if (err)
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goto out;
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skb->truesize += dlen - plen;
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__skb_put(skb, dlen - plen);
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memcpy(skb->data, scratch, dlen);
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out:
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put_cpu();
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return err;
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}
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static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err = -ENOMEM;
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struct iphdr *iph;
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struct ip_comp_hdr *ipch;
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if (skb_linearize_cow(skb))
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goto out;
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skb->ip_summed = CHECKSUM_NONE;
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/* Remove ipcomp header and decompress original payload */
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iph = skb->nh.iph;
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ipch = (void *)skb->data;
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iph->protocol = ipch->nexthdr;
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skb->h.raw = skb->nh.raw + sizeof(*ipch);
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__skb_pull(skb, sizeof(*ipch));
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err = ipcomp_decompress(x, skb);
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out:
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return err;
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}
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static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err, plen, dlen, ihlen;
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struct iphdr *iph = skb->nh.iph;
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struct ipcomp_data *ipcd = x->data;
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u8 *start, *scratch;
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struct crypto_comp *tfm;
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int cpu;
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ihlen = iph->ihl * 4;
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plen = skb->len - ihlen;
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dlen = IPCOMP_SCRATCH_SIZE;
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start = skb->data + ihlen;
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cpu = get_cpu();
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scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
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tfm = *per_cpu_ptr(ipcd->tfms, cpu);
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err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
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if (err)
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goto out;
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if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
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err = -EMSGSIZE;
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goto out;
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}
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memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
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put_cpu();
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pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
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return 0;
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out:
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put_cpu();
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return err;
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}
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static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err;
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struct iphdr *iph;
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struct ip_comp_hdr *ipch;
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struct ipcomp_data *ipcd = x->data;
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int hdr_len = 0;
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iph = skb->nh.iph;
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iph->tot_len = htons(skb->len);
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hdr_len = iph->ihl * 4;
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if ((skb->len - hdr_len) < ipcd->threshold) {
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/* Don't bother compressing */
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goto out_ok;
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}
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if (skb_linearize_cow(skb))
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goto out_ok;
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err = ipcomp_compress(x, skb);
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iph = skb->nh.iph;
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if (err) {
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goto out_ok;
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}
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/* Install ipcomp header, convert into ipcomp datagram. */
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iph->tot_len = htons(skb->len);
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ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
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ipch->nexthdr = iph->protocol;
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ipch->flags = 0;
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ipch->cpi = htons((u16 )ntohl(x->id.spi));
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iph->protocol = IPPROTO_COMP;
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ip_send_check(iph);
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return 0;
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out_ok:
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if (x->props.mode == XFRM_MODE_TUNNEL)
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ip_send_check(iph);
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return 0;
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}
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static void ipcomp4_err(struct sk_buff *skb, u32 info)
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{
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__be32 spi;
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struct iphdr *iph = (struct iphdr *)skb->data;
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struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
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struct xfrm_state *x;
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if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
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skb->h.icmph->code != ICMP_FRAG_NEEDED)
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return;
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spi = htonl(ntohs(ipch->cpi));
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x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
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spi, IPPROTO_COMP, AF_INET);
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if (!x)
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return;
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NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
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spi, NIPQUAD(iph->daddr));
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xfrm_state_put(x);
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}
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/* We always hold one tunnel user reference to indicate a tunnel */
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static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
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{
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struct xfrm_state *t;
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u8 mode = XFRM_MODE_TUNNEL;
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t = xfrm_state_alloc();
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if (t == NULL)
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goto out;
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t->id.proto = IPPROTO_IPIP;
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t->id.spi = x->props.saddr.a4;
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t->id.daddr.a4 = x->id.daddr.a4;
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memcpy(&t->sel, &x->sel, sizeof(t->sel));
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t->props.family = AF_INET;
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if (x->props.mode == XFRM_MODE_BEET)
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mode = x->props.mode;
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t->props.mode = mode;
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t->props.saddr.a4 = x->props.saddr.a4;
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t->props.flags = x->props.flags;
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if (xfrm_init_state(t))
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goto error;
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atomic_set(&t->tunnel_users, 1);
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out:
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return t;
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error:
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t->km.state = XFRM_STATE_DEAD;
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xfrm_state_put(t);
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t = NULL;
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goto out;
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}
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/*
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* Must be protected by xfrm_cfg_mutex. State and tunnel user references are
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* always incremented on success.
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*/
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static int ipcomp_tunnel_attach(struct xfrm_state *x)
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{
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int err = 0;
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struct xfrm_state *t;
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t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
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x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
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if (!t) {
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t = ipcomp_tunnel_create(x);
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if (!t) {
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err = -EINVAL;
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goto out;
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}
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xfrm_state_insert(t);
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xfrm_state_hold(t);
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}
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x->tunnel = t;
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atomic_inc(&t->tunnel_users);
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out:
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return err;
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}
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static void ipcomp_free_scratches(void)
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{
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int i;
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void **scratches;
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if (--ipcomp_scratch_users)
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return;
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scratches = ipcomp_scratches;
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if (!scratches)
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return;
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for_each_possible_cpu(i)
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vfree(*per_cpu_ptr(scratches, i));
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free_percpu(scratches);
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}
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static void **ipcomp_alloc_scratches(void)
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{
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int i;
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void **scratches;
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if (ipcomp_scratch_users++)
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return ipcomp_scratches;
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scratches = alloc_percpu(void *);
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if (!scratches)
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return NULL;
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ipcomp_scratches = scratches;
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for_each_possible_cpu(i) {
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void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
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if (!scratch)
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return NULL;
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*per_cpu_ptr(scratches, i) = scratch;
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}
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return scratches;
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}
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static void ipcomp_free_tfms(struct crypto_comp **tfms)
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{
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struct ipcomp_tfms *pos;
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int cpu;
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list_for_each_entry(pos, &ipcomp_tfms_list, list) {
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if (pos->tfms == tfms)
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break;
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}
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BUG_TRAP(pos);
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if (--pos->users)
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return;
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list_del(&pos->list);
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kfree(pos);
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if (!tfms)
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return;
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for_each_possible_cpu(cpu) {
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struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
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crypto_free_comp(tfm);
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}
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free_percpu(tfms);
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}
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static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
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{
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struct ipcomp_tfms *pos;
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struct crypto_comp **tfms;
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int cpu;
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/* This can be any valid CPU ID so we don't need locking. */
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cpu = raw_smp_processor_id();
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list_for_each_entry(pos, &ipcomp_tfms_list, list) {
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struct crypto_comp *tfm;
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tfms = pos->tfms;
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tfm = *per_cpu_ptr(tfms, cpu);
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if (!strcmp(crypto_comp_name(tfm), alg_name)) {
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pos->users++;
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return tfms;
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}
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}
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pos = kmalloc(sizeof(*pos), GFP_KERNEL);
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if (!pos)
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return NULL;
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pos->users = 1;
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INIT_LIST_HEAD(&pos->list);
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list_add(&pos->list, &ipcomp_tfms_list);
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pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
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if (!tfms)
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goto error;
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for_each_possible_cpu(cpu) {
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struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
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CRYPTO_ALG_ASYNC);
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if (!tfm)
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goto error;
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*per_cpu_ptr(tfms, cpu) = tfm;
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}
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return tfms;
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error:
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ipcomp_free_tfms(tfms);
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return NULL;
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}
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static void ipcomp_free_data(struct ipcomp_data *ipcd)
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{
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if (ipcd->tfms)
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ipcomp_free_tfms(ipcd->tfms);
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ipcomp_free_scratches();
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}
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static void ipcomp_destroy(struct xfrm_state *x)
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{
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struct ipcomp_data *ipcd = x->data;
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if (!ipcd)
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return;
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xfrm_state_delete_tunnel(x);
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mutex_lock(&ipcomp_resource_mutex);
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ipcomp_free_data(ipcd);
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mutex_unlock(&ipcomp_resource_mutex);
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kfree(ipcd);
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}
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static int ipcomp_init_state(struct xfrm_state *x)
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{
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int err;
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struct ipcomp_data *ipcd;
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struct xfrm_algo_desc *calg_desc;
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err = -EINVAL;
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if (!x->calg)
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goto out;
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if (x->encap)
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goto out;
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err = -ENOMEM;
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ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
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if (!ipcd)
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goto out;
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x->props.header_len = 0;
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if (x->props.mode == XFRM_MODE_TUNNEL)
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x->props.header_len += sizeof(struct iphdr);
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mutex_lock(&ipcomp_resource_mutex);
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if (!ipcomp_alloc_scratches())
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goto error;
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ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
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if (!ipcd->tfms)
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goto error;
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mutex_unlock(&ipcomp_resource_mutex);
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if (x->props.mode == XFRM_MODE_TUNNEL) {
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err = ipcomp_tunnel_attach(x);
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if (err)
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goto error_tunnel;
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}
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calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
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BUG_ON(!calg_desc);
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ipcd->threshold = calg_desc->uinfo.comp.threshold;
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x->data = ipcd;
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err = 0;
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out:
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return err;
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error_tunnel:
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mutex_lock(&ipcomp_resource_mutex);
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error:
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ipcomp_free_data(ipcd);
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mutex_unlock(&ipcomp_resource_mutex);
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kfree(ipcd);
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goto out;
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}
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static struct xfrm_type ipcomp_type = {
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.description = "IPCOMP4",
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.owner = THIS_MODULE,
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.proto = IPPROTO_COMP,
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.init_state = ipcomp_init_state,
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.destructor = ipcomp_destroy,
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.input = ipcomp_input,
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.output = ipcomp_output
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};
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static struct net_protocol ipcomp4_protocol = {
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.handler = xfrm4_rcv,
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.err_handler = ipcomp4_err,
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.no_policy = 1,
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};
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static int __init ipcomp4_init(void)
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{
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if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
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printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
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return -EAGAIN;
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}
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if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
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printk(KERN_INFO "ipcomp init: can't add protocol\n");
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xfrm_unregister_type(&ipcomp_type, AF_INET);
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return -EAGAIN;
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}
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return 0;
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}
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static void __exit ipcomp4_fini(void)
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{
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if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
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printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
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if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
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printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
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}
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module_init(ipcomp4_init);
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module_exit(ipcomp4_fini);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
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MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
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