path: root/net/ipv4/esp4.c

#define pr_fmt(fmt) "IPsec: " fmt

#include <crypto/aead.h>
#include <crypto/authenc.h>
#include <linux/err.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/esp.h>
#include <linux/scatterlist.h>
#include <linux/kernel.h>
#include <linux/pfkeyv2.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/in6.h>
#include <net/icmp.h>
#include <net/protocol.h>
#include <net/udp.h>

#include <linux/highmem.h>

struct esp_skb_cb {
	struct xfrm_skb_cb xfrm;
	void *tmp;
};

struct esp_output_extra {
	__be32 seqhi;
	u32 esphoff;
};

#define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))

static u32 esp4_get_mtu(struct xfrm_state *x, int mtu);

/*
 * Allocate an AEAD request structure with extra space for SG and IV.
 *
 * For alignment considerations the IV is placed at the front, followed
 * by the request and finally the SG list.
 *
 * TODO: Use spare space in skb for this where possible.
 */
static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int extralen)
{
	unsigned int len;

	len = extralen;

	len += crypto_aead_ivsize(aead);

	if (len) {
		len += crypto_aead_alignmask(aead) &
		       ~(crypto_tfm_ctx_alignment() - 1);
		len = ALIGN(len, crypto_tfm_ctx_alignment());
	}

	len += sizeof(struct aead_request) + crypto_aead_reqsize(aead);
	len = ALIGN(len, __alignof__(struct scatterlist));

	len += sizeof(struct scatterlist) * nfrags;

	return kmalloc(len, GFP_ATOMIC);
}

static inline void *esp_tmp_extra(void *tmp)
{
	return PTR_ALIGN(tmp, __alignof__(struct esp_output_extra));
}

static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int extralen)
{
	return crypto_aead_ivsize(aead) ?
	       PTR_ALIGN((u8 *)tmp + extralen,
			 crypto_aead_alignmask(aead) + 1) : tmp + extralen;
}

static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)
{
	struct aead_request *req;

	req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
				crypto_tfm_ctx_alignment());
	aead_request_set_tfm(req, aead);
	return req;
}

static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
					     struct aead_request *req)
{
	return (void *)ALIGN((unsigned long)(req + 1) +
			     crypto_aead_reqsize(aead),
			     __alignof__(struct scatterlist));
}

static void esp_ssg_unref(struct xfrm_state *x, void *tmp)
{
	struct esp_output_extra *extra = esp_tmp_extra(tmp);
	struct crypto_aead *aead = x->data;
	int extralen = 0;
	u8 *iv;
	struct aead_request *req;
	struct scatterlist *sg;

	if (x->props.flags & XFRM_STATE_ESN)
		extralen += sizeof(*extra);

	extra = esp_tmp_extra(tmp);
	iv = esp_tmp_iv(aead, tmp, extralen);
	req = esp_tmp_req(aead, iv);

	/* Unref skb_frag_pages in the src scatterlist if necessary.
	 * Skip the first sg which comes from skb->data.
	 */
	if (req->src != req->dst)
		for (sg = sg_next(req->src); sg; sg = sg_next(sg))
			put_page(sg_page(sg));
}

static void esp_output_done(struct crypto_async_request *base, int err)
{
	struct sk_buff *skb = base->data;
	struct xfrm_offload *xo = xfrm_offload(skb);
	void *tmp;
	struct xfrm_state *x;

	if (xo && (xo->flags & XFRM_DEV_RESUME))
		x = skb->sp->xvec[skb->sp->len - 1];
	else
		x = skb_dst(skb)->xfrm;

	tmp = ESP_SKB_CB(skb)->tmp;
	esp_ssg_unref(x, tmp);
	kfree(tmp);

	if (xo && (xo->flags & XFRM_DEV_RESUME)) {
		if (err) {
			XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
			kfree_skb(skb);
			return;
		}

		skb_push(skb, skb->data - skb_mac_header(skb));
		secpath_reset(skb);
		xfrm_dev_resume(skb);
	} else {
		xfrm_output_resume(skb, err);
	}
}

/* Move ESP header back into place. */
static void esp_restore_header(struct sk_buff *skb, unsigned int offset)
{
	struct ip_esp_hdr *esph = (void *)(skb->data + offset);
	void *tmp = ESP_SKB_CB(skb)->tmp;
	__be32 *seqhi = esp_tmp_extra(tmp);

	esph->seq_no = esph->spi;
	esph->spi = *seqhi;
}

static