1 files changed, 524 insertions, 0 deletions

diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
new file mode 100644
index 0000000..1a23c52
--- /dev/null
+++ b/net/ipv4/ipcomp.c
@@ -0,0 +1,524 @@
+/*
+ * IP Payload Compression Protocol (IPComp) - RFC3173.
+ *
+ * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
+ *
+ * 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.
+ *
+ * Todo:
+ *   - Tunable compression parameters.
+ *   - Compression stats.
+ *   - Adaptive compression.
+ */
+#include <linux/config.h>
+#include <linux/module.h>
+#include <asm/scatterlist.h>
+#include <asm/semaphore.h>
+#include <linux/crypto.h>
+#include <linux/pfkeyv2.h>
+#include <linux/percpu.h>
+#include <linux/smp.h>
+#include <linux/list.h>
+#include <linux/vmalloc.h>
+#include <linux/rtnetlink.h>
+#include <net/ip.h>
+#include <net/xfrm.h>
+#include <net/icmp.h>
+#include <net/ipcomp.h>
+
+struct ipcomp_tfms {
+	struct list_head list;
+	struct crypto_tfm **tfms;
+	int users;
+};
+
+static DECLARE_MUTEX(ipcomp_resource_sem);
+static void **ipcomp_scratches;
+static int ipcomp_scratch_users;
+static LIST_HEAD(ipcomp_tfms_list);
+
+static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err, plen, dlen;
+	struct iphdr *iph;
+	struct ipcomp_data *ipcd = x->data;
+	u8 *start, *scratch;
+	struct crypto_tfm *tfm;
+	int cpu;
+	
+	plen = skb->len;
+	dlen = IPCOMP_SCRATCH_SIZE;
+	start = skb->data;
+
+	cpu = get_cpu();
+	scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
+	tfm = *per_cpu_ptr(ipcd->tfms, cpu);
+
+	err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
+	if (err)
+		goto out;
+
+	if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
+	if (err)
+		goto out;
+		
+	skb_put(skb, dlen - plen);
+	memcpy(skb->data, scratch, dlen);
+	iph = skb->nh.iph;
+	iph->tot_len = htons(dlen + iph->ihl * 4);
+out:	
+	put_cpu();
+	return err;
+}
+
+static int ipcomp_input(struct xfrm_state *x,
+                        struct xfrm_decap_state *decap, struct sk_buff *skb)
+{
+	u8 nexthdr;
+	int err = 0;
+	struct iphdr *iph;
+	union {
+		struct iphdr	iph;
+		char 		buf[60];
+	} tmp_iph;
+
+
+	if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
+	    skb_linearize(skb, GFP_ATOMIC) != 0) {
+	    	err = -ENOMEM;
+	    	goto out;
+	}
+
+	skb->ip_summed = CHECKSUM_NONE;
+
+	/* Remove ipcomp header and decompress original payload */	
+	iph = skb->nh.iph;
+	memcpy(&tmp_iph, iph, iph->ihl * 4);
+	nexthdr = *(u8 *)skb->data;
+	skb_pull(skb, sizeof(struct ip_comp_hdr));
+	skb->nh.raw += sizeof(struct ip_comp_hdr);
+	memcpy(skb->nh.raw, &tmp_iph, tmp_iph.iph.ihl * 4);
+	iph = skb->nh.iph;
+	iph->tot_len = htons(ntohs(iph->tot_len) - sizeof(struct ip_comp_hdr));
+	iph->protocol = nexthdr;
+	skb->h.raw = skb->data;
+	err = ipcomp_decompress(x, skb);
+
+out:	
+	return err;
+}
+
+static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err, plen, dlen, ihlen;
+	struct iphdr *iph = skb->nh.iph;
+	struct ipcomp_data *ipcd = x->data;
+	u8 *start, *scratch;
+	struct crypto_tfm *tfm;
+	int cpu;
+	
+	ihlen = iph->ihl * 4;
+	plen = skb->len - ihlen;
+	dlen = IPCOMP_SCRATCH_SIZE;
+	start = skb->data + ihlen;
+
+	cpu = get_cpu();
+	scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
+	tfm = *per_cpu_ptr(ipcd->tfms, cpu);
+
+	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
+	if (err)
+		goto out;
+
+	if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
+		err = -EMSGSIZE;
+		goto out;
+	}
+	
+	memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
+	put_cpu();
+
+	pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
+	return 0;
+	
+out:	
+	put_cpu();
+	return err;
+}
+
+static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err;
+	struct iphdr *iph;
+	struct ip_comp_hdr *ipch;
+	struct ipcomp_data *ipcd = x->data;
+	int hdr_len = 0;
+
+	iph = skb->nh.iph;
+	iph->tot_len = htons(skb->len);
+	hdr_len = iph->ihl * 4;
+	if ((skb->len - hdr_len) < ipcd->threshold) {
+		/* Don't bother compressing */
+		goto out_ok;
+	}
+
+	if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
+	    skb_linearize(skb, GFP_ATOMIC) != 0) {
+		goto out_ok;
+	}
+	
+	err = ipcomp_compress(x, skb);
+	iph = skb->nh.iph;
+
+	if (err) {
+		goto out_ok;
+	}
+
+	/* Install ipcomp header, convert into ipcomp datagram. */
+	iph->tot_len = htons(skb->len);
+	ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
+	ipch->nexthdr = iph->protocol;
+	ipch->flags = 0;
+	ipch->cpi = htons((u16 )ntohl(x->id.spi));
+	iph->protocol = IPPROTO_COMP;
+	ip_send_check(iph);
+	return 0;
+
+out_ok:
+	if (x->props.mode)
+		ip_send_check(iph);
+	return 0;
+}
+
+static void ipcomp4_err(struct sk_buff *skb, u32 info)
+{
+	u32 spi;
+	struct iphdr *iph = (struct iphdr *)skb->data;
+	struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
+	struct xfrm_state *x;
+
+	if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
+	    skb->h.icmph->code != ICMP_FRAG_NEEDED)
+		return;
+
+	spi = ntohl(ntohs(ipch->cpi));
+	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
+	                      spi, IPPROTO_COMP, AF_INET);
+	if (!x)
+		return;
+	NETDEBUG(printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
+	       spi, NIPQUAD(iph->daddr)));
+	xfrm_state_put(x);
+}
+
+/* We always hold one tunnel user reference to indicate a tunnel */ 
+static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
+{
+	struct xfrm_state *t;
+	
+	t = xfrm_state_alloc();
+	if (t == NULL)
+		goto out;
+
+	t->id.proto = IPPROTO_IPIP;
+	t->id.spi = x->props.saddr.a4;
+	t->id.daddr.a4 = x->id.daddr.a4;
+	memcpy(&t->sel, &x->sel, sizeof(t->sel));
+	t->props.family = AF_INET;
+	t->props.mode = 1;
+	t->props.saddr.a4 = x->props.saddr.a4;
+	t->props.flags = x->props.flags;
+	
+	t->type = xfrm_get_type(IPPROTO_IPIP, t->props.family);
+	if (t->type == NULL)
+		goto error;
+		
+	if (t->type->init_state(t, NULL))
+		goto error;
+
+	t->km.state = XFRM_STATE_VALID;
+	atomic_set(&t->tunnel_users, 1);
+out:
+	return t;
+
+error:
+	t->km.state = XFRM_STATE_DEAD;
+	xfrm_state_put(t);
+	t = NULL;
+	goto out;
+}
+
+/*
+ * Must be protected by xfrm_cfg_sem.  State and tunnel user references are
+ * always incremented on success.
+ */
+static int ipcomp_tunnel_attach(struct xfrm_state *x)
+{
+	int err = 0;
+	struct xfrm_state *t;
+
+	t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
+	                      x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
+	if (!t) {
+		t = ipcomp_tunnel_create(x);
+		if (!t) {
+			err = -EINVAL;
+			goto out;
+		}
+		xfrm_state_insert(t);
+		xfrm_state_hold(t);
+	}
+	x->tunnel = t;
+	atomic_inc(&t->tunnel_users);
+out:
+	return err;
+}
+
+static void ipcomp_free_scratches(void)
+{
+	int i;
+	void **scratches;
+
+	if (--ipcomp_scratch_users)
+		return;
+
+	scratches = ipcomp_scratches;
+	if (!scratches)
+		return;
+
+	for_each_cpu(i) {
+		void *scratch = *per_cpu_ptr(scratches, i);
+		if (scratch)
+			vfree(scratch);
+	}
+
+	free_percpu(scratches);
+}
+
+static void **ipcomp_alloc_scratches(void)
+{
+	int i;
+	void **scratches;
+
+	if (ipcomp_scratch_users++)
+		return ipcomp_scratches;
+
+	scratches = alloc_percpu(void *);
+	if (!scratches)
+		return NULL;
+
+	ipcomp_scratches = scratches;
+
+	for_each_cpu(i) {
+		void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
+		if (!scratch)
+			return NULL;
+		*per_cpu_ptr(scratches, i) = scratch;
+	}
+
+	return scratches;
+}
+
+static void ipcomp_free_tfms(struct crypto_tfm **tfms)
+{
+	struct ipcomp_tfms *pos;
+	int cpu;
+
+	list_for_each_entry(pos, &ipcomp_tfms_list, list) {
+		if (pos->tfms == tfms)
+			break;
+	}
+
+	BUG_TRAP(pos);
+
+	if (--pos->users)
+		return;
+
+	list_del(&pos->list);
+	kfree(pos);
+
+	if (!tfms)
+		return;
+
+	for_each_cpu(cpu) {
+		struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
+		if (tfm)
+			crypto_free_tfm(tfm);
+	}
+	free_percpu(tfms);
+}
+
+static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name)
+{
+	struct ipcomp_tfms *pos;
+	struct crypto_tfm **tfms;
+	int cpu;
+
+	/* This can be any valid CPU ID so we don't need locking. */
+	cpu = smp_processor_id();
+
+	list_for_each_entry(pos, &ipcomp_tfms_list, list) {
+		struct crypto_tfm *tfm;
+
+		tfms = pos->tfms;
+		tfm = *per_cpu_ptr(tfms, cpu);
+
+		if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
+			pos->users++;
+			return tfms;
+		}
+	}
+
+	pos = kmalloc(sizeof(*pos), GFP_KERNEL);
+	if (!pos)
+		return NULL;
+
+	pos->users = 1;
+	INIT_LIST_HEAD(&pos->list);
+	list_add(&pos->list, &ipcomp_tfms_list);
+
+	pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
+	if (!tfms)
+		goto error;
+
+	for_each_cpu(cpu) {
+		struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
+		if (!tfm)
+			goto error;
+		*per_cpu_ptr(tfms, cpu) = tfm;
+	}
+
+	return tfms;
+
+error:
+	ipcomp_free_tfms(tfms);
+	return NULL;
+}
+
+static void ipcomp_free_data(struct ipcomp_data *ipcd)
+{
+	if (ipcd->tfms)
+		ipcomp_free_tfms(ipcd->tfms);
+	ipcomp_free_scratches();
+}
+
+static void ipcomp_destroy(struct xfrm_state *x)
+{
+	struct ipcomp_data *ipcd = x->data;
+	if (!ipcd)
+		return;
+	xfrm_state_delete_tunnel(x);
+	down(&ipcomp_resource_sem);
+	ipcomp_free_data(ipcd);
+	up(&ipcomp_resource_sem);
+	kfree(ipcd);
+}
+
+static int ipcomp_init_state(struct xfrm_state *x, void *args)
+{
+	int err;
+	struct ipcomp_data *ipcd;
+	struct xfrm_algo_desc *calg_desc;
+
+	err = -EINVAL;
+	if (!x->calg)
+		goto out;
+
+	if (x->encap)
+		goto out;
+
+	err = -ENOMEM;
+	ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
+	if (!ipcd)
+		goto out;
+
+	memset(ipcd, 0, sizeof(*ipcd));
+	x->props.header_len = 0;
+	if (x->props.mode)
+		x->props.header_len += sizeof(struct iphdr);
+
+	down(&ipcomp_resource_sem);
+	if (!ipcomp_alloc_scratches())
+		goto error;
+
+	ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
+	if (!ipcd->tfms)
+		goto error;
+	up(&ipcomp_resource_sem);
+
+	if (x->props.mode) {
+		err = ipcomp_tunnel_attach(x);
+		if (err)
+			goto error_tunnel;
+	}
+
+	calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
+	BUG_ON(!calg_desc);
+	ipcd->threshold = calg_desc->uinfo.comp.threshold;
+	x->data = ipcd;
+	err = 0;
+out:
+	return err;
+
+error_tunnel:
+	down(&ipcomp_resource_sem);
+error:
+	ipcomp_free_data(ipcd);
+	up(&ipcomp_resource_sem);
+	kfree(ipcd);
+	goto out;
+}
+
+static struct xfrm_type ipcomp_type = {
+	.description	= "IPCOMP4",
+	.owner		= THIS_MODULE,
+	.proto	     	= IPPROTO_COMP,
+	.init_state	= ipcomp_init_state,
+	.destructor	= ipcomp_destroy,
+	.input		= ipcomp_input,
+	.output		= ipcomp_output
+};
+
+static struct net_protocol ipcomp4_protocol = {
+	.handler	=	xfrm4_rcv,
+	.err_handler	=	ipcomp4_err,
+	.no_policy	=	1,
+};
+
+static int __init ipcomp4_init(void)
+{
+	if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
+		printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
+		return -EAGAIN;
+	}
+	if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
+		printk(KERN_INFO "ipcomp init: can't add protocol\n");
+		xfrm_unregister_type(&ipcomp_type, AF_INET);
+		return -EAGAIN;
+	}
+	return 0;
+}
+
+static void __exit ipcomp4_fini(void)
+{
+	if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
+		printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
+	if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
+		printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
+}
+
+module_init(ipcomp4_init);
+module_exit(ipcomp4_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
+MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
+