ipsec: ipcomp - Merge IPComp implementations

This patch merges the IPv4/IPv6 IPComp implementations since most
of the code is identical.  As a result future enhancements will no
longer need to be duplicated.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 356 insertions, 0 deletions

diff --git a/net/xfrm/Kconfig b/net/xfrm/Kconfig
index 9201ef8ad90e..6d081674515f 100644
--- a/net/xfrm/Kconfig
+++ b/net/xfrm/Kconfig
@@ -46,6 +46,12 @@ config XFRM_STATISTICS
 
           If unsure, say N.
 
+config XFRM_IPCOMP
+        tristate
+        select XFRM
+        select CRYPTO
+        select CRYPTO_DEFLATE
+
 config NET_KEY
         tristate "PF_KEY sockets"
         select XFRM
diff --git a/net/xfrm/Makefile b/net/xfrm/Makefile
index 332cfb0ff566..0f439a72ccab 100644
--- a/net/xfrm/Makefile
+++ b/net/xfrm/Makefile
@@ -6,4 +6,5 @@ obj-$(CONFIG_XFRM) := xfrm_policy.o xfrm_state.o xfrm_hash.o \
                       xfrm_input.o xfrm_output.o xfrm_algo.o
 obj-$(CONFIG_XFRM_STATISTICS) += xfrm_proc.o
 obj-$(CONFIG_XFRM_USER) += xfrm_user.o
+obj-$(CONFIG_XFRM_IPCOMP) += xfrm_ipcomp.o
 
diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
new file mode 100644
index 000000000000..b51e804fbbad
--- /dev/null
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -0,0 +1,349 @@
+/*
+ * IP Payload Compression Protocol (IPComp) - RFC3173.
+ *
+ * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
+ * Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.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/crypto.h>
+#include <linux/err.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/percpu.h>
+#include <linux/rtnetlink.h>
+#include <linux/smp.h>
+#include <linux/vmalloc.h>
+#include <net/ip.h>
+#include <net/ipcomp.h>
+#include <net/xfrm.h>
+
+struct ipcomp_tfms {
+        struct list_head list;
+        struct crypto_comp **tfms;
+        int users;
+};
+
+static DEFINE_MUTEX(ipcomp_resource_mutex);
+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)
+{
+        struct ipcomp_data *ipcd = x->data;
+        const int plen = skb->len;
+        int dlen = IPCOMP_SCRATCH_SIZE;
+        const u8 *start = skb->data;
+        const int cpu = get_cpu();
+        u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
+        struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
+        int 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->truesize += dlen - plen;
+        __skb_put(skb, dlen - plen);
+        skb_copy_to_linear_data(skb, scratch, dlen);
+out:
+        put_cpu();
+        return err;
+}
+
+int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+        int nexthdr;
+        int err = -ENOMEM;
+        struct ip_comp_hdr *ipch;
+
+        if (skb_linearize_cow(skb))
+                goto out;
+
+        skb->ip_summed = CHECKSUM_NONE;
+
+        /* Remove ipcomp header and decompress original payload */
+        ipch = (void *)skb->data;
+        nexthdr = ipch->nexthdr;
+
+        skb->transport_header = skb->network_header + sizeof(*ipch);
+        __skb_pull(skb, sizeof(*ipch));
+        err = ipcomp_decompress(x, skb);
+        if (err)
+                goto out;
+
+        err = nexthdr;
+
+out:
+        return err;
+}
+EXPORT_SYMBOL_GPL(ipcomp_input);
+
+static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
+{
+        struct ipcomp_data *ipcd = x->data;
+        const int plen = skb->len;
+        int dlen = IPCOMP_SCRATCH_SIZE;
+        u8 *start = skb->data;
+        const int cpu = get_cpu();
+        u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
+        struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
+        int err;
+
+        local_bh_disable();
+        err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
+        local_bh_enable();
+        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, dlen + sizeof(struct ip_comp_hdr));
+        return 0;
+
+out:
+        put_cpu();
+        return err;
+}
+
+int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+        int err;
+        struct ip_comp_hdr *ipch;
+        struct ipcomp_data *ipcd = x->data;
+
+        if (skb->len < ipcd->threshold) {
+                /* Don't bother compressing */
+                goto out_ok;
+        }
+
+        if (skb_linearize_cow(skb))
+                goto out_ok;
+
+        err = ipcomp_compress(x, skb);
+
+        if (err) {
+                goto out_ok;
+        }
+
+        /* Install ipcomp header, convert into ipcomp datagram. */
+        ipch = ip_comp_hdr(skb);
+        ipch->nexthdr = *skb_mac_header(skb);
+        ipch->flags = 0;
+        ipch->cpi = htons((u16 )ntohl(x->id.spi));
+        *skb_mac_header(skb) = IPPROTO_COMP;
+out_ok:
+        skb_push(skb, -skb_network_offset(skb));
+        return 0;
+}
+EXPORT_SYMBOL_GPL(ipcomp_output);
+
+static void ipcomp_free_scratches(void)
+{
+        int i;
+        void **scratches;
+
+        if (--ipcomp_scratch_users)
+                return;
+
+        scratches = ipcomp_scratches;
+        if (!scratches)
+                return;
+
+        for_each_possible_cpu(i)
+                vfree(*per_cpu_ptr(scratches, i));
+
+        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_possible_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_comp **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_possible_cpu(cpu) {
+                struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
+                crypto_free_comp(tfm);
+        }
+        free_percpu(tfms);
+}
+
+static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
+{
+        struct ipcomp_tfms *pos;
+        struct crypto_comp **tfms;
+        int cpu;
+
+        /* This can be any valid CPU ID so we don't need locking. */
+        cpu = raw_smp_processor_id();
+
+        list_for_each_entry(pos, &ipcomp_tfms_list, list) {
+                struct crypto_comp *tfm;
+
+                tfms = pos->tfms;
+                tfm = *per_cpu_ptr(tfms, cpu);
+
+                if (!strcmp(crypto_comp_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_comp *);
+        if (!tfms)
+                goto error;
+
+        for_each_possible_cpu(cpu) {
+                struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
+                                                            CRYPTO_ALG_ASYNC);
+                if (IS_ERR(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();
+}
+
+void ipcomp_destroy(struct xfrm_state *x)
+{
+        struct ipcomp_data *ipcd = x->data;
+        if (!ipcd)
+                return;
+        xfrm_state_delete_tunnel(x);
+        mutex_lock(&ipcomp_resource_mutex);
+        ipcomp_free_data(ipcd);
+        mutex_unlock(&ipcomp_resource_mutex);
+        kfree(ipcd);
+}
+EXPORT_SYMBOL_GPL(ipcomp_destroy);
+
+int ipcomp_init_state(struct xfrm_state *x)
+{
+        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 = kzalloc(sizeof(*ipcd), GFP_KERNEL);
+        if (!ipcd)
+                goto out;
+
+        mutex_lock(&ipcomp_resource_mutex);
+        if (!ipcomp_alloc_scratches())
+                goto error;
+
+        ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
+        if (!ipcd->tfms)
+                goto error;
+        mutex_unlock(&ipcomp_resource_mutex);
+
+        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:
+        ipcomp_free_data(ipcd);
+        mutex_unlock(&ipcomp_resource_mutex);
+        kfree(ipcd);
+        goto out;
+}
+EXPORT_SYMBOL_GPL(ipcomp_init_state);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
+MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");