![David S. Miller](/assets/img/avatar_default.png)
With ip_rt_frag_needed() removed, we have to explicitly update PMTU information in every ICMP error handler. Create two helper functions to facilitate this. 1) ipv4_sk_update_pmtu() This updates the PMTU when we have a socket context to work with. 2) ipv4_update_pmtu() Raw version, used when no socket context is available. For this interface, we essentially just pass in explicit arguments for the flow identity information we would have extracted from the socket. And you'll notice that ipv4_sk_update_pmtu() is simply implemented in terms of ipv4_update_pmtu() Note that __ip_route_output_key() is used, rather than something like ip_route_output_flow() or ip_route_output_key(). This is because we absolutely do not want to end up with a route that does IPSEC encapsulation and the like. Instead, we only want the route that would get us to the node described by the outermost IP header. Reported-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: David S. Miller <davem@davemloft.net>
540 lines
12 KiB
C
540 lines
12 KiB
C
#define pr_fmt(fmt) "IPsec: " fmt
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#include <crypto/hash.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <net/ip.h>
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#include <net/xfrm.h>
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#include <net/ah.h>
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#include <linux/crypto.h>
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#include <linux/pfkeyv2.h>
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#include <linux/scatterlist.h>
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#include <net/icmp.h>
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#include <net/protocol.h>
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struct ah_skb_cb {
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struct xfrm_skb_cb xfrm;
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void *tmp;
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};
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#define AH_SKB_CB(__skb) ((struct ah_skb_cb *)&((__skb)->cb[0]))
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static void *ah_alloc_tmp(struct crypto_ahash *ahash, int nfrags,
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unsigned int size)
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{
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unsigned int len;
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len = size + crypto_ahash_digestsize(ahash) +
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(crypto_ahash_alignmask(ahash) &
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~(crypto_tfm_ctx_alignment() - 1));
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len = ALIGN(len, crypto_tfm_ctx_alignment());
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len += sizeof(struct ahash_request) + crypto_ahash_reqsize(ahash);
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len = ALIGN(len, __alignof__(struct scatterlist));
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len += sizeof(struct scatterlist) * nfrags;
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return kmalloc(len, GFP_ATOMIC);
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}
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static inline u8 *ah_tmp_auth(void *tmp, unsigned int offset)
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{
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return tmp + offset;
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}
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static inline u8 *ah_tmp_icv(struct crypto_ahash *ahash, void *tmp,
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unsigned int offset)
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{
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return PTR_ALIGN((u8 *)tmp + offset, crypto_ahash_alignmask(ahash) + 1);
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}
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static inline struct ahash_request *ah_tmp_req(struct crypto_ahash *ahash,
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u8 *icv)
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{
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struct ahash_request *req;
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req = (void *)PTR_ALIGN(icv + crypto_ahash_digestsize(ahash),
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crypto_tfm_ctx_alignment());
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ahash_request_set_tfm(req, ahash);
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return req;
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}
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static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
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struct ahash_request *req)
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{
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return (void *)ALIGN((unsigned long)(req + 1) +
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crypto_ahash_reqsize(ahash),
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__alignof__(struct scatterlist));
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}
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/* Clear mutable options and find final destination to substitute
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* into IP header for icv calculation. Options are already checked
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* for validity, so paranoia is not required. */
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static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr)
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{
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unsigned char *optptr = (unsigned char *)(iph+1);
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int l = iph->ihl*4 - sizeof(struct iphdr);
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int optlen;
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while (l > 0) {
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switch (*optptr) {
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case IPOPT_END:
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return 0;
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case IPOPT_NOOP:
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l--;
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optptr++;
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continue;
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}
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optlen = optptr[1];
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if (optlen<2 || optlen>l)
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return -EINVAL;
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switch (*optptr) {
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case IPOPT_SEC:
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case 0x85: /* Some "Extended Security" crap. */
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case IPOPT_CIPSO:
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case IPOPT_RA:
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case 0x80|21: /* RFC1770 */
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break;
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case IPOPT_LSRR:
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case IPOPT_SSRR:
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if (optlen < 6)
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return -EINVAL;
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memcpy(daddr, optptr+optlen-4, 4);
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/* Fall through */
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default:
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memset(optptr, 0, optlen);
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}
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l -= optlen;
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optptr += optlen;
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}
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return 0;
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}
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static void ah_output_done(struct crypto_async_request *base, int err)
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{
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u8 *icv;
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struct iphdr *iph;
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struct sk_buff *skb = base->data;
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struct xfrm_state *x = skb_dst(skb)->xfrm;
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struct ah_data *ahp = x->data;
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struct iphdr *top_iph = ip_hdr(skb);
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struct ip_auth_hdr *ah = ip_auth_hdr(skb);
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int ihl = ip_hdrlen(skb);
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iph = AH_SKB_CB(skb)->tmp;
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icv = ah_tmp_icv(ahp->ahash, iph, ihl);
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memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
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top_iph->tos = iph->tos;
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top_iph->ttl = iph->ttl;
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top_iph->frag_off = iph->frag_off;
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if (top_iph->ihl != 5) {
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top_iph->daddr = iph->daddr;
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memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
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}
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kfree(AH_SKB_CB(skb)->tmp);
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xfrm_output_resume(skb, err);
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}
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static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err;
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int nfrags;
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int ihl;
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u8 *icv;
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struct sk_buff *trailer;
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struct crypto_ahash *ahash;
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struct ahash_request *req;
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struct scatterlist *sg;
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struct iphdr *iph, *top_iph;
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struct ip_auth_hdr *ah;
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struct ah_data *ahp;
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ahp = x->data;
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ahash = ahp->ahash;
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if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
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goto out;
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nfrags = err;
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skb_push(skb, -skb_network_offset(skb));
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ah = ip_auth_hdr(skb);
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ihl = ip_hdrlen(skb);
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err = -ENOMEM;
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iph = ah_alloc_tmp(ahash, nfrags, ihl);
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if (!iph)
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goto out;
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icv = ah_tmp_icv(ahash, iph, ihl);
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req = ah_tmp_req(ahash, icv);
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sg = ah_req_sg(ahash, req);
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memset(ah->auth_data, 0, ahp->icv_trunc_len);
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top_iph = ip_hdr(skb);
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iph->tos = top_iph->tos;
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iph->ttl = top_iph->ttl;
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iph->frag_off = top_iph->frag_off;
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if (top_iph->ihl != 5) {
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iph->daddr = top_iph->daddr;
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memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
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err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
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if (err)
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goto out_free;
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}
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ah->nexthdr = *skb_mac_header(skb);
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*skb_mac_header(skb) = IPPROTO_AH;
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top_iph->tos = 0;
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top_iph->tot_len = htons(skb->len);
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top_iph->frag_off = 0;
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top_iph->ttl = 0;
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top_iph->check = 0;
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if (x->props.flags & XFRM_STATE_ALIGN4)
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ah->hdrlen = (XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
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else
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ah->hdrlen = (XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len) >> 2) - 2;
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ah->reserved = 0;
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ah->spi = x->id.spi;
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ah->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
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sg_init_table(sg, nfrags);
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skb_to_sgvec(skb, sg, 0, skb->len);
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ahash_request_set_crypt(req, sg, icv, skb->len);
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ahash_request_set_callback(req, 0, ah_output_done, skb);
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AH_SKB_CB(skb)->tmp = iph;
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err = crypto_ahash_digest(req);
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if (err) {
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if (err == -EINPROGRESS)
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goto out;
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if (err == -EBUSY)
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err = NET_XMIT_DROP;
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goto out_free;
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}
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memcpy(ah->auth_data, icv, ahp->icv_trunc_len);
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top_iph->tos = iph->tos;
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top_iph->ttl = iph->ttl;
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top_iph->frag_off = iph->frag_off;
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if (top_iph->ihl != 5) {
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top_iph->daddr = iph->daddr;
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memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
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}
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out_free:
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kfree(iph);
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out:
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return err;
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}
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static void ah_input_done(struct crypto_async_request *base, int err)
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{
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u8 *auth_data;
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u8 *icv;
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struct iphdr *work_iph;
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struct sk_buff *skb = base->data;
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struct xfrm_state *x = xfrm_input_state(skb);
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struct ah_data *ahp = x->data;
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struct ip_auth_hdr *ah = ip_auth_hdr(skb);
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int ihl = ip_hdrlen(skb);
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int ah_hlen = (ah->hdrlen + 2) << 2;
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work_iph = AH_SKB_CB(skb)->tmp;
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auth_data = ah_tmp_auth(work_iph, ihl);
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icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
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err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
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if (err)
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goto out;
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err = ah->nexthdr;
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skb->network_header += ah_hlen;
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memcpy(skb_network_header(skb), work_iph, ihl);
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__skb_pull(skb, ah_hlen + ihl);
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skb_set_transport_header(skb, -ihl);
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out:
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kfree(AH_SKB_CB(skb)->tmp);
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xfrm_input_resume(skb, err);
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}
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static int ah_input(struct xfrm_state *x, struct sk_buff *skb)
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{
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int ah_hlen;
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int ihl;
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int nexthdr;
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int nfrags;
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u8 *auth_data;
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u8 *icv;
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struct sk_buff *trailer;
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struct crypto_ahash *ahash;
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struct ahash_request *req;
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struct scatterlist *sg;
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struct iphdr *iph, *work_iph;
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struct ip_auth_hdr *ah;
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struct ah_data *ahp;
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int err = -ENOMEM;
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if (!pskb_may_pull(skb, sizeof(*ah)))
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goto out;
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ah = (struct ip_auth_hdr *)skb->data;
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ahp = x->data;
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ahash = ahp->ahash;
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nexthdr = ah->nexthdr;
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ah_hlen = (ah->hdrlen + 2) << 2;
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if (x->props.flags & XFRM_STATE_ALIGN4) {
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if (ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_full_len) &&
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ah_hlen != XFRM_ALIGN4(sizeof(*ah) + ahp->icv_trunc_len))
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goto out;
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} else {
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if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
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ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))
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goto out;
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}
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if (!pskb_may_pull(skb, ah_hlen))
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goto out;
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/* We are going to _remove_ AH header to keep sockets happy,
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* so... Later this can change. */
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if (skb_cloned(skb) &&
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pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
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goto out;
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skb->ip_summed = CHECKSUM_NONE;
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if ((err = skb_cow_data(skb, 0, &trailer)) < 0)
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goto out;
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nfrags = err;
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ah = (struct ip_auth_hdr *)skb->data;
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iph = ip_hdr(skb);
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ihl = ip_hdrlen(skb);
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work_iph = ah_alloc_tmp(ahash, nfrags, ihl + ahp->icv_trunc_len);
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if (!work_iph)
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goto out;
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auth_data = ah_tmp_auth(work_iph, ihl);
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icv = ah_tmp_icv(ahash, auth_data, ahp->icv_trunc_len);
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req = ah_tmp_req(ahash, icv);
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sg = ah_req_sg(ahash, req);
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memcpy(work_iph, iph, ihl);
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memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
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memset(ah->auth_data, 0, ahp->icv_trunc_len);
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iph->ttl = 0;
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iph->tos = 0;
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iph->frag_off = 0;
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iph->check = 0;
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if (ihl > sizeof(*iph)) {
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__be32 dummy;
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err = ip_clear_mutable_options(iph, &dummy);
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if (err)
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goto out_free;
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}
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skb_push(skb, ihl);
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sg_init_table(sg, nfrags);
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skb_to_sgvec(skb, sg, 0, skb->len);
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ahash_request_set_crypt(req, sg, icv, skb->len);
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ahash_request_set_callback(req, 0, ah_input_done, skb);
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AH_SKB_CB(skb)->tmp = work_iph;
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err = crypto_ahash_digest(req);
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if (err) {
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if (err == -EINPROGRESS)
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goto out;
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goto out_free;
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}
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err = memcmp(icv, auth_data, ahp->icv_trunc_len) ? -EBADMSG: 0;
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if (err)
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goto out_free;
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skb->network_header += ah_hlen;
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memcpy(skb_network_header(skb), work_iph, ihl);
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__skb_pull(skb, ah_hlen + ihl);
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skb_set_transport_header(skb, -ihl);
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err = nexthdr;
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out_free:
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kfree (work_iph);
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out:
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return err;
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}
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static void ah4_err(struct sk_buff *skb, u32 info)
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{
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struct net *net = dev_net(skb->dev);
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const struct iphdr *iph = (const struct iphdr *)skb->data;
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struct ip_auth_hdr *ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
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struct xfrm_state *x;
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if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
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icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
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return;
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x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
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ah->spi, IPPROTO_AH, AF_INET);
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if (!x)
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return;
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pr_debug("pmtu discovery on SA AH/%08x/%08x\n",
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ntohl(ah->spi), ntohl(iph->daddr));
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ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_AH, 0);
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xfrm_state_put(x);
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}
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static int ah_init_state(struct xfrm_state *x)
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{
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struct ah_data *ahp = NULL;
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struct xfrm_algo_desc *aalg_desc;
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struct crypto_ahash *ahash;
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if (!x->aalg)
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goto error;
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if (x->encap)
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goto error;
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ahp = kzalloc(sizeof(*ahp), GFP_KERNEL);
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if (!ahp)
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return -ENOMEM;
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ahash = crypto_alloc_ahash(x->aalg->alg_name, 0, 0);
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if (IS_ERR(ahash))
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goto error;
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ahp->ahash = ahash;
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if (crypto_ahash_setkey(ahash, x->aalg->alg_key,
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(x->aalg->alg_key_len + 7) / 8))
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goto error;
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/*
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* Lookup the algorithm description maintained by xfrm_algo,
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* verify crypto transform properties, and store information
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* we need for AH processing. This lookup cannot fail here
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* after a successful crypto_alloc_ahash().
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*/
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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_ahash_digestsize(ahash)) {
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pr_info("%s: %s digestsize %u != %hu\n",
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__func__, x->aalg->alg_name,
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crypto_ahash_digestsize(ahash),
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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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ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
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ahp->icv_trunc_len = x->aalg->alg_trunc_len/8;
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BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
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if (x->props.flags & XFRM_STATE_ALIGN4)
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x->props.header_len = XFRM_ALIGN4(sizeof(struct ip_auth_hdr) +
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ahp->icv_trunc_len);
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else
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x->props.header_len = XFRM_ALIGN8(sizeof(struct ip_auth_hdr) +
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ahp->icv_trunc_len);
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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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x->data = ahp;
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return 0;
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error:
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if (ahp) {
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crypto_free_ahash(ahp->ahash);
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kfree(ahp);
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}
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return -EINVAL;
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|
}
|
|
|
|
static void ah_destroy(struct xfrm_state *x)
|
|
{
|
|
struct ah_data *ahp = x->data;
|
|
|
|
if (!ahp)
|
|
return;
|
|
|
|
crypto_free_ahash(ahp->ahash);
|
|
kfree(ahp);
|
|
}
|
|
|
|
|
|
static const struct xfrm_type ah_type =
|
|
{
|
|
.description = "AH4",
|
|
.owner = THIS_MODULE,
|
|
.proto = IPPROTO_AH,
|
|
.flags = XFRM_TYPE_REPLAY_PROT,
|
|
.init_state = ah_init_state,
|
|
.destructor = ah_destroy,
|
|
.input = ah_input,
|
|
.output = ah_output
|
|
};
|
|
|
|
static const struct net_protocol ah4_protocol = {
|
|
.handler = xfrm4_rcv,
|
|
.err_handler = ah4_err,
|
|
.no_policy = 1,
|
|
.netns_ok = 1,
|
|
};
|
|
|
|
static int __init ah4_init(void)
|
|
{
|
|
if (xfrm_register_type(&ah_type, AF_INET) < 0) {
|
|
pr_info("%s: can't add xfrm type\n", __func__);
|
|
return -EAGAIN;
|
|
}
|
|
if (inet_add_protocol(&ah4_protocol, IPPROTO_AH) < 0) {
|
|
pr_info("%s: can't add protocol\n", __func__);
|
|
xfrm_unregister_type(&ah_type, AF_INET);
|
|
return -EAGAIN;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static void __exit ah4_fini(void)
|
|
{
|
|
if (inet_del_protocol(&ah4_protocol, IPPROTO_AH) < 0)
|
|
pr_info("%s: can't remove protocol\n", __func__);
|
|
if (xfrm_unregister_type(&ah_type, AF_INET) < 0)
|
|
pr_info("%s: can't remove xfrm type\n", __func__);
|
|
}
|
|
|
|
module_init(ah4_init);
|
|
module_exit(ah4_fini);
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);
|