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![Herbert Xu](/assets/img/avatar_default.png)
Now that we have xfrm_mode objects we can move the transport mode specific input decapsulation code into xfrm_mode_transport. This removes duplicate code as well as unnecessary header movement in case of tunnel mode SAs since we will discard the original IP header immediately. This also fixes a minor bug for transport-mode ESP where the IP payload length is set to the correct value minus the header length (with extension headers for IPv6). Of course the other neat thing is that we no longer have to allocate temporary buffers to hold the IP headers for ESP and IPComp. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
443 lines
11 KiB
C
443 lines
11 KiB
C
#include <linux/config.h>
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#include <linux/module.h>
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#include <net/ip.h>
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#include <net/xfrm.h>
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#include <net/esp.h>
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#include <asm/scatterlist.h>
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#include <linux/crypto.h>
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#include <linux/kernel.h>
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#include <linux/pfkeyv2.h>
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#include <linux/random.h>
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#include <net/icmp.h>
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#include <net/protocol.h>
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#include <net/udp.h>
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static int esp_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 *top_iph;
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struct ip_esp_hdr *esph;
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struct crypto_tfm *tfm;
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struct esp_data *esp;
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struct sk_buff *trailer;
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int blksize;
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int clen;
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int alen;
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int nfrags;
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/* Strip IP+ESP header. */
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__skb_pull(skb, skb->h.raw - skb->data);
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/* Now skb is pure payload to encrypt */
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err = -ENOMEM;
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/* Round to block size */
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clen = skb->len;
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esp = x->data;
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alen = esp->auth.icv_trunc_len;
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tfm = esp->conf.tfm;
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blksize = ALIGN(crypto_tfm_alg_blocksize(tfm), 4);
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clen = ALIGN(clen + 2, blksize);
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if (esp->conf.padlen)
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clen = ALIGN(clen, esp->conf.padlen);
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if ((nfrags = skb_cow_data(skb, clen-skb->len+alen, &trailer)) < 0)
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goto error;
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/* Fill padding... */
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do {
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int i;
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for (i=0; i<clen-skb->len - 2; i++)
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*(u8*)(trailer->tail + i) = i+1;
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} while (0);
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*(u8*)(trailer->tail + clen-skb->len - 2) = (clen - skb->len)-2;
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pskb_put(skb, trailer, clen - skb->len);
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__skb_push(skb, skb->data - skb->nh.raw);
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top_iph = skb->nh.iph;
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esph = (struct ip_esp_hdr *)(skb->nh.raw + top_iph->ihl*4);
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top_iph->tot_len = htons(skb->len + alen);
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*(u8*)(trailer->tail - 1) = top_iph->protocol;
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/* this is non-NULL only with UDP Encapsulation */
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if (x->encap) {
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struct xfrm_encap_tmpl *encap = x->encap;
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struct udphdr *uh;
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u32 *udpdata32;
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uh = (struct udphdr *)esph;
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uh->source = encap->encap_sport;
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uh->dest = encap->encap_dport;
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uh->len = htons(skb->len + alen - top_iph->ihl*4);
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uh->check = 0;
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switch (encap->encap_type) {
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default:
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case UDP_ENCAP_ESPINUDP:
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esph = (struct ip_esp_hdr *)(uh + 1);
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break;
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case UDP_ENCAP_ESPINUDP_NON_IKE:
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udpdata32 = (u32 *)(uh + 1);
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udpdata32[0] = udpdata32[1] = 0;
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esph = (struct ip_esp_hdr *)(udpdata32 + 2);
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break;
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}
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top_iph->protocol = IPPROTO_UDP;
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} else
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top_iph->protocol = IPPROTO_ESP;
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esph->spi = x->id.spi;
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esph->seq_no = htonl(++x->replay.oseq);
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xfrm_aevent_doreplay(x);
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if (esp->conf.ivlen)
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crypto_cipher_set_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
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do {
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struct scatterlist *sg = &esp->sgbuf[0];
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if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
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sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
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if (!sg)
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goto error;
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}
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skb_to_sgvec(skb, sg, esph->enc_data+esp->conf.ivlen-skb->data, clen);
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crypto_cipher_encrypt(tfm, sg, sg, clen);
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if (unlikely(sg != &esp->sgbuf[0]))
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kfree(sg);
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} while (0);
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if (esp->conf.ivlen) {
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memcpy(esph->enc_data, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
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crypto_cipher_get_iv(tfm, esp->conf.ivec, crypto_tfm_alg_ivsize(tfm));
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}
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if (esp->auth.icv_full_len) {
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esp->auth.icv(esp, skb, (u8*)esph-skb->data,
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sizeof(struct ip_esp_hdr) + esp->conf.ivlen+clen, trailer->tail);
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pskb_put(skb, trailer, alen);
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}
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ip_send_check(top_iph);
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err = 0;
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error:
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return err;
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}
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/*
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* Note: detecting truncated vs. non-truncated authentication data is very
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* expensive, so we only support truncated data, which is the recommended
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* and common case.
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*/
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static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
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{
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struct iphdr *iph;
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struct ip_esp_hdr *esph;
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struct esp_data *esp = x->data;
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struct sk_buff *trailer;
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int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
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int alen = esp->auth.icv_trunc_len;
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int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
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int nfrags;
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int ihl;
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u8 nexthdr[2];
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struct scatterlist *sg;
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int padlen;
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if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
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goto out;
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if (elen <= 0 || (elen & (blksize-1)))
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goto out;
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/* If integrity check is required, do this. */
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if (esp->auth.icv_full_len) {
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u8 sum[esp->auth.icv_full_len];
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u8 sum1[alen];
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esp->auth.icv(esp, skb, 0, skb->len-alen, sum);
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if (skb_copy_bits(skb, skb->len-alen, sum1, alen))
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BUG();
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if (unlikely(memcmp(sum, sum1, alen))) {
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x->stats.integrity_failed++;
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goto out;
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}
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}
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if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0)
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goto out;
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skb->ip_summed = CHECKSUM_NONE;
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esph = (struct ip_esp_hdr*)skb->data;
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/* Get ivec. This can be wrong, check against another impls. */
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if (esp->conf.ivlen)
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crypto_cipher_set_iv(esp->conf.tfm, esph->enc_data, crypto_tfm_alg_ivsize(esp->conf.tfm));
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sg = &esp->sgbuf[0];
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if (unlikely(nfrags > ESP_NUM_FAST_SG)) {
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sg = kmalloc(sizeof(struct scatterlist)*nfrags, GFP_ATOMIC);
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if (!sg)
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goto out;
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}
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skb_to_sgvec(skb, sg, sizeof(struct ip_esp_hdr) + esp->conf.ivlen, elen);
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crypto_cipher_decrypt(esp->conf.tfm, sg, sg, elen);
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if (unlikely(sg != &esp->sgbuf[0]))
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kfree(sg);
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if (skb_copy_bits(skb, skb->len-alen-2, nexthdr, 2))
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BUG();
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padlen = nexthdr[0];
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if (padlen+2 >= elen)
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goto out;
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/* ... check padding bits here. Silly. :-) */
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iph = skb->nh.iph;
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ihl = iph->ihl * 4;
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if (x->encap) {
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struct xfrm_encap_tmpl *encap = x->encap;
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struct udphdr *uh = (void *)(skb->nh.raw + ihl);
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/*
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* 1) if the NAT-T peer's IP or port changed then
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* advertize the change to the keying daemon.
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* This is an inbound SA, so just compare
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* SRC ports.
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*/
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if (iph->saddr != x->props.saddr.a4 ||
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uh->source != encap->encap_sport) {
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xfrm_address_t ipaddr;
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ipaddr.a4 = iph->saddr;
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km_new_mapping(x, &ipaddr, uh->source);
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/* XXX: perhaps add an extra
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* policy check here, to see
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* if we should allow or
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* reject a packet from a
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* different source
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* address/port.
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*/
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}
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/*
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* 2) ignore UDP/TCP checksums in case
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* of NAT-T in Transport Mode, or
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* perform other post-processing fixes
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* as per draft-ietf-ipsec-udp-encaps-06,
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* section 3.1.2
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*/
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if (!x->props.mode)
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skb->ip_summed = CHECKSUM_UNNECESSARY;
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}
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iph->protocol = nexthdr[1];
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pskb_trim(skb, skb->len - alen - padlen - 2);
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skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - ihl;
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return 0;
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out:
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return -EINVAL;
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}
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static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
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{
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struct esp_data *esp = x->data;
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u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4);
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if (x->props.mode) {
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mtu = ALIGN(mtu + 2, blksize);
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} else {
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/* The worst case. */
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mtu = ALIGN(mtu + 2, 4) + blksize - 4;
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}
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if (esp->conf.padlen)
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mtu = ALIGN(mtu, esp->conf.padlen);
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return mtu + x->props.header_len + esp->auth.icv_trunc_len;
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}
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static void esp4_err(struct sk_buff *skb, u32 info)
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{
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struct iphdr *iph = (struct iphdr*)skb->data;
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struct ip_esp_hdr *esph = (struct ip_esp_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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x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, esph->spi, IPPROTO_ESP, AF_INET);
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if (!x)
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return;
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NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
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ntohl(esph->spi), ntohl(iph->daddr));
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xfrm_state_put(x);
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}
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static void esp_destroy(struct xfrm_state *x)
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{
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struct esp_data *esp = x->data;
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if (!esp)
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return;
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crypto_free_tfm(esp->conf.tfm);
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esp->conf.tfm = NULL;
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kfree(esp->conf.ivec);
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esp->conf.ivec = NULL;
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crypto_free_tfm(esp->auth.tfm);
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esp->auth.tfm = NULL;
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kfree(esp->auth.work_icv);
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esp->auth.work_icv = NULL;
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kfree(esp);
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}
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static int esp_init_state(struct xfrm_state *x)
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{
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struct esp_data *esp = NULL;
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/* null auth and encryption can have zero length keys */
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if (x->aalg) {
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if (x->aalg->alg_key_len > 512)
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goto error;
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}
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if (x->ealg == NULL)
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goto error;
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esp = kmalloc(sizeof(*esp), GFP_KERNEL);
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if (esp == NULL)
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return -ENOMEM;
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memset(esp, 0, sizeof(*esp));
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if (x->aalg) {
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struct xfrm_algo_desc *aalg_desc;
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esp->auth.key = x->aalg->alg_key;
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esp->auth.key_len = (x->aalg->alg_key_len+7)/8;
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esp->auth.tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
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if (esp->auth.tfm == NULL)
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goto error;
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esp->auth.icv = esp_hmac_digest;
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aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);
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BUG_ON(!aalg_desc);
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if (aalg_desc->uinfo.auth.icv_fullbits/8 !=
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crypto_tfm_alg_digestsize(esp->auth.tfm)) {
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NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",
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x->aalg->alg_name,
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crypto_tfm_alg_digestsize(esp->auth.tfm),
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aalg_desc->uinfo.auth.icv_fullbits/8);
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goto error;
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}
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esp->auth.icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
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esp->auth.icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
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esp->auth.work_icv = kmalloc(esp->auth.icv_full_len, GFP_KERNEL);
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if (!esp->auth.work_icv)
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goto error;
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}
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esp->conf.key = x->ealg->alg_key;
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esp->conf.key_len = (x->ealg->alg_key_len+7)/8;
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if (x->props.ealgo == SADB_EALG_NULL)
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esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_ECB);
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else
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esp->conf.tfm = crypto_alloc_tfm(x->ealg->alg_name, CRYPTO_TFM_MODE_CBC);
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if (esp->conf.tfm == NULL)
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goto error;
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esp->conf.ivlen = crypto_tfm_alg_ivsize(esp->conf.tfm);
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esp->conf.padlen = 0;
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if (esp->conf.ivlen) {
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esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
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if (unlikely(esp->conf.ivec == NULL))
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goto error;
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get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
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}
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if (crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len))
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goto error;
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x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
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if (x->props.mode)
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x->props.header_len += sizeof(struct iphdr);
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if (x->encap) {
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struct xfrm_encap_tmpl *encap = x->encap;
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switch (encap->encap_type) {
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default:
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goto error;
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case UDP_ENCAP_ESPINUDP:
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x->props.header_len += sizeof(struct udphdr);
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break;
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case UDP_ENCAP_ESPINUDP_NON_IKE:
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x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
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break;
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}
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}
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x->data = esp;
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x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len;
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return 0;
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error:
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x->data = esp;
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esp_destroy(x);
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x->data = NULL;
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return -EINVAL;
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}
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static struct xfrm_type esp_type =
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{
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.description = "ESP4",
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.owner = THIS_MODULE,
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.proto = IPPROTO_ESP,
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.init_state = esp_init_state,
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.destructor = esp_destroy,
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.get_max_size = esp4_get_max_size,
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.input = esp_input,
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.output = esp_output
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};
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static struct net_protocol esp4_protocol = {
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.handler = xfrm4_rcv,
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.err_handler = esp4_err,
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.no_policy = 1,
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};
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static int __init esp4_init(void)
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{
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if (xfrm_register_type(&esp_type, AF_INET) < 0) {
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printk(KERN_INFO "ip esp 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(&esp4_protocol, IPPROTO_ESP) < 0) {
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printk(KERN_INFO "ip esp init: can't add protocol\n");
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xfrm_unregister_type(&esp_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 esp4_fini(void)
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{
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if (inet_del_protocol(&esp4_protocol, IPPROTO_ESP) < 0)
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printk(KERN_INFO "ip esp close: can't remove protocol\n");
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if (xfrm_unregister_type(&esp_type, AF_INET) < 0)
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printk(KERN_INFO "ip esp close: can't remove xfrm type\n");
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}
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module_init(esp4_init);
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module_exit(esp4_fini);
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MODULE_LICENSE("GPL");
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