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599 lines
14 KiB
599 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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#define pr_fmt(fmt) "IPsec: " fmt |
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#include <crypto/algapi.h> |
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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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fallthrough; |
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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->sk, 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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int seqhi_len = 0; |
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__be32 *seqhi; |
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int sglists = 0; |
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struct scatterlist *seqhisg; |
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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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if (x->props.flags & XFRM_STATE_ESN) { |
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sglists = 1; |
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seqhi_len = sizeof(*seqhi); |
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} |
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err = -ENOMEM; |
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iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + seqhi_len); |
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if (!iph) |
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goto out; |
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seqhi = (__be32 *)((char *)iph + ihl); |
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icv = ah_tmp_icv(ahash, seqhi, seqhi_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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seqhisg = sg + nfrags; |
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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 + sglists); |
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err = skb_to_sgvec_nomark(skb, sg, 0, skb->len); |
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if (unlikely(err < 0)) |
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goto out_free; |
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if (x->props.flags & XFRM_STATE_ESN) { |
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/* Attach seqhi sg right after packet payload */ |
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*seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); |
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sg_set_buf(seqhisg, seqhi, seqhi_len); |
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} |
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ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_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 == -ENOSPC) |
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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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if (err) |
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goto out; |
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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 = crypto_memneq(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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if (x->props.mode == XFRM_MODE_TUNNEL) |
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skb_reset_transport_header(skb); |
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else |
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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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int seqhi_len = 0; |
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__be32 *seqhi; |
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int sglists = 0; |
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struct scatterlist *seqhisg; |
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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_unclone(skb, 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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if (x->props.flags & XFRM_STATE_ESN) { |
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sglists = 1; |
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seqhi_len = sizeof(*seqhi); |
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} |
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work_iph = ah_alloc_tmp(ahash, nfrags + sglists, ihl + |
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ahp->icv_trunc_len + seqhi_len); |
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if (!work_iph) { |
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err = -ENOMEM; |
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goto out; |
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} |
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seqhi = (__be32 *)((char *)work_iph + ihl); |
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auth_data = ah_tmp_auth(seqhi, seqhi_len); |
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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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seqhisg = sg + nfrags; |
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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 + sglists); |
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err = skb_to_sgvec_nomark(skb, sg, 0, skb->len); |
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if (unlikely(err < 0)) |
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goto out_free; |
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if (x->props.flags & XFRM_STATE_ESN) { |
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/* Attach seqhi sg right after packet payload */ |
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*seqhi = XFRM_SKB_CB(skb)->seq.input.hi; |
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sg_set_buf(seqhisg, seqhi, seqhi_len); |
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} |
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ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_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 = crypto_memneq(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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if (x->props.mode == XFRM_MODE_TUNNEL) |
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skb_reset_transport_header(skb); |
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else |
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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 int 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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switch (icmp_hdr(skb)->type) { |
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case ICMP_DEST_UNREACH: |
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if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) |
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return 0; |
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break; |
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case ICMP_REDIRECT: |
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break; |
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default: |
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return 0; |
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} |
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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 0; |
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if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) |
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ipv4_update_pmtu(skb, net, info, 0, IPPROTO_AH); |
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else |
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ipv4_redirect(skb, net, 0, IPPROTO_AH); |
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xfrm_state_put(x); |
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return 0; |
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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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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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} |
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|
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static void ah_destroy(struct xfrm_state *x) |
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{ |
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struct ah_data *ahp = x->data; |
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|
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if (!ahp) |
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return; |
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|
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crypto_free_ahash(ahp->ahash); |
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kfree(ahp); |
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} |
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|
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static int ah4_rcv_cb(struct sk_buff *skb, int err) |
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{ |
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return 0; |
|
} |
|
|
|
static const struct xfrm_type ah_type = |
|
{ |
|
.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 struct xfrm4_protocol ah4_protocol = { |
|
.handler = xfrm4_rcv, |
|
.input_handler = xfrm_input, |
|
.cb_handler = ah4_rcv_cb, |
|
.err_handler = ah4_err, |
|
.priority = 0, |
|
}; |
|
|
|
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 (xfrm4_protocol_register(&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 (xfrm4_protocol_deregister(&ah4_protocol, IPPROTO_AH) < 0) |
|
pr_info("%s: can't remove protocol\n", __func__); |
|
xfrm_unregister_type(&ah_type, AF_INET); |
|
} |
|
|
|
module_init(ah4_init); |
|
module_exit(ah4_fini); |
|
MODULE_LICENSE("GPL"); |
|
MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_AH);
|
|
|