478 lines
11 KiB
C
478 lines
11 KiB
C
/*
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* Copyright (C)2002 USAGI/WIDE Project
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Authors
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*
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* Mitsuru KANDA @USAGI : IPv6 Support
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* Kazunori MIYAZAWA @USAGI :
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* Kunihiro Ishiguro <kunihiro@ipinfusion.com>
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*
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* This file is derived from net/ipv4/ah.c.
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*/
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#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/ah.h>
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#include <linux/crypto.h>
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#include <linux/pfkeyv2.h>
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#include <linux/string.h>
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#include <net/icmp.h>
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#include <net/ipv6.h>
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#include <net/xfrm.h>
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#include <asm/scatterlist.h>
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static int zero_out_mutable_opts(struct ipv6_opt_hdr *opthdr)
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{
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u8 *opt = (u8 *)opthdr;
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int len = ipv6_optlen(opthdr);
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int off = 0;
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int optlen = 0;
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off += 2;
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len -= 2;
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while (len > 0) {
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switch (opt[off]) {
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case IPV6_TLV_PAD0:
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optlen = 1;
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break;
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default:
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if (len < 2)
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goto bad;
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optlen = opt[off+1]+2;
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if (len < optlen)
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goto bad;
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if (opt[off] & 0x20)
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memset(&opt[off+2], 0, opt[off+1]);
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break;
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}
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off += optlen;
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len -= optlen;
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}
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if (len == 0)
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return 1;
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bad:
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return 0;
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}
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/**
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* ipv6_rearrange_rthdr - rearrange IPv6 routing header
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* @iph: IPv6 header
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* @rthdr: routing header
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*
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* Rearrange the destination address in @iph and the addresses in @rthdr
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* so that they appear in the order they will at the final destination.
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* See Appendix A2 of RFC 2402 for details.
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*/
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static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
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{
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int segments, segments_left;
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struct in6_addr *addrs;
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struct in6_addr final_addr;
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segments_left = rthdr->segments_left;
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if (segments_left == 0)
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return;
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rthdr->segments_left = 0;
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/* The value of rthdr->hdrlen has been verified either by the system
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* call if it is locally generated, or by ipv6_rthdr_rcv() for incoming
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* packets. So we can assume that it is even and that segments is
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* greater than or equal to segments_left.
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*
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* For the same reason we can assume that this option is of type 0.
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*/
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segments = rthdr->hdrlen >> 1;
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addrs = ((struct rt0_hdr *)rthdr)->addr;
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ipv6_addr_copy(&final_addr, addrs + segments - 1);
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addrs += segments - segments_left;
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memmove(addrs + 1, addrs, (segments_left - 1) * sizeof(*addrs));
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ipv6_addr_copy(addrs, &iph->daddr);
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ipv6_addr_copy(&iph->daddr, &final_addr);
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}
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static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len)
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{
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union {
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struct ipv6hdr *iph;
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struct ipv6_opt_hdr *opth;
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struct ipv6_rt_hdr *rth;
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char *raw;
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} exthdr = { .iph = iph };
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char *end = exthdr.raw + len;
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int nexthdr = iph->nexthdr;
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exthdr.iph++;
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while (exthdr.raw < end) {
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switch (nexthdr) {
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case NEXTHDR_HOP:
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case NEXTHDR_DEST:
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if (!zero_out_mutable_opts(exthdr.opth)) {
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LIMIT_NETDEBUG(
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KERN_WARNING "overrun %sopts\n",
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nexthdr == NEXTHDR_HOP ?
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"hop" : "dest");
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return -EINVAL;
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}
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break;
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case NEXTHDR_ROUTING:
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ipv6_rearrange_rthdr(iph, exthdr.rth);
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break;
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default :
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return 0;
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}
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nexthdr = exthdr.opth->nexthdr;
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exthdr.raw += ipv6_optlen(exthdr.opth);
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}
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return 0;
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}
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static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err;
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int extlen;
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struct ipv6hdr *top_iph;
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struct ip_auth_hdr *ah;
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struct ah_data *ahp;
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u8 nexthdr;
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char tmp_base[8];
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struct {
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struct in6_addr daddr;
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char hdrs[0];
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} *tmp_ext;
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top_iph = (struct ipv6hdr *)skb->data;
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top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
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nexthdr = *skb->nh.raw;
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*skb->nh.raw = IPPROTO_AH;
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/* When there are no extension headers, we only need to save the first
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* 8 bytes of the base IP header.
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*/
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memcpy(tmp_base, top_iph, sizeof(tmp_base));
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tmp_ext = NULL;
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extlen = skb->h.raw - (unsigned char *)(top_iph + 1);
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if (extlen) {
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extlen += sizeof(*tmp_ext);
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tmp_ext = kmalloc(extlen, GFP_ATOMIC);
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if (!tmp_ext) {
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err = -ENOMEM;
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goto error;
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}
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memcpy(tmp_ext, &top_iph->daddr, extlen);
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err = ipv6_clear_mutable_options(top_iph,
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extlen - sizeof(*tmp_ext) +
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sizeof(*top_iph));
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if (err)
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goto error_free_iph;
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}
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ah = (struct ip_auth_hdr *)skb->h.raw;
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ah->nexthdr = nexthdr;
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top_iph->priority = 0;
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top_iph->flow_lbl[0] = 0;
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top_iph->flow_lbl[1] = 0;
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top_iph->flow_lbl[2] = 0;
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top_iph->hop_limit = 0;
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ahp = x->data;
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ah->hdrlen = (XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) +
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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(++x->replay.oseq);
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ahp->icv(ahp, skb, ah->auth_data);
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err = 0;
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memcpy(top_iph, tmp_base, sizeof(tmp_base));
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if (tmp_ext) {
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memcpy(&top_iph->daddr, tmp_ext, extlen);
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error_free_iph:
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kfree(tmp_ext);
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}
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error:
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return err;
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}
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static int ah6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
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{
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/*
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* Before process AH
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* [IPv6][Ext1][Ext2][AH][Dest][Payload]
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* |<-------------->| hdr_len
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*
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* To erase AH:
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* Keeping copy of cleared headers. After AH processing,
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* Moving the pointer of skb->nh.raw by using skb_pull as long as AH
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* header length. Then copy back the copy as long as hdr_len
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* If destination header following AH exists, copy it into after [Ext2].
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*
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* |<>|[IPv6][Ext1][Ext2][Dest][Payload]
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* There is offset of AH before IPv6 header after the process.
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*/
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struct ipv6_auth_hdr *ah;
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struct ah_data *ahp;
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unsigned char *tmp_hdr = NULL;
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u16 hdr_len;
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u16 ah_hlen;
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int nexthdr;
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if (!pskb_may_pull(skb, sizeof(struct ip_auth_hdr)))
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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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hdr_len = skb->data - skb->nh.raw;
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ah = (struct ipv6_auth_hdr*)skb->data;
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ahp = x->data;
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nexthdr = ah->nexthdr;
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ah_hlen = (ah->hdrlen + 2) << 2;
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if (ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_full_len) &&
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ah_hlen != XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len))
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goto out;
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if (!pskb_may_pull(skb, ah_hlen))
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goto out;
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tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
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if (!tmp_hdr)
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goto out;
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memcpy(tmp_hdr, skb->nh.raw, hdr_len);
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if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len))
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goto out;
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skb->nh.ipv6h->priority = 0;
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skb->nh.ipv6h->flow_lbl[0] = 0;
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skb->nh.ipv6h->flow_lbl[1] = 0;
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skb->nh.ipv6h->flow_lbl[2] = 0;
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skb->nh.ipv6h->hop_limit = 0;
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{
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u8 auth_data[MAX_AH_AUTH_LEN];
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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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skb_push(skb, skb->data - skb->nh.raw);
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ahp->icv(ahp, skb, ah->auth_data);
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if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
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LIMIT_NETDEBUG(KERN_WARNING "ipsec ah authentication error\n");
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x->stats.integrity_failed++;
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goto free_out;
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}
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}
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skb->nh.raw = skb_pull(skb, ah_hlen);
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memcpy(skb->nh.raw, tmp_hdr, hdr_len);
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skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
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skb_pull(skb, hdr_len);
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skb->h.raw = skb->data;
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kfree(tmp_hdr);
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return nexthdr;
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free_out:
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kfree(tmp_hdr);
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out:
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return -EINVAL;
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}
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static void ah6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
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int type, int code, int offset, __u32 info)
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{
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struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
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struct ip_auth_hdr *ah = (struct ip_auth_hdr*)(skb->data+offset);
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struct xfrm_state *x;
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if (type != ICMPV6_DEST_UNREACH &&
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type != ICMPV6_PKT_TOOBIG)
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return;
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x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, ah->spi, IPPROTO_AH, AF_INET6);
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if (!x)
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return;
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NETDEBUG(KERN_DEBUG "pmtu discovery on SA AH/%08x/"
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"%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
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ntohl(ah->spi), NIP6(iph->daddr));
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xfrm_state_put(x);
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}
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static int ah6_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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if (!x->aalg)
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goto error;
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/* null auth can use a zero length key */
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if (x->aalg->alg_key_len > 512)
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goto error;
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if (x->encap)
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goto error;
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ahp = kmalloc(sizeof(*ahp), GFP_KERNEL);
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if (ahp == NULL)
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return -ENOMEM;
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memset(ahp, 0, sizeof(*ahp));
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ahp->key = x->aalg->alg_key;
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ahp->key_len = (x->aalg->alg_key_len+7)/8;
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ahp->tfm = crypto_alloc_tfm(x->aalg->alg_name, 0);
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if (!ahp->tfm)
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goto error;
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ahp->icv = ah_hmac_digest;
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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_tfm().
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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_tfm_alg_digestsize(ahp->tfm)) {
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printk(KERN_INFO "AH: %s digestsize %u != %hu\n",
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x->aalg->alg_name, crypto_tfm_alg_digestsize(ahp->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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ahp->icv_full_len = aalg_desc->uinfo.auth.icv_fullbits/8;
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ahp->icv_trunc_len = aalg_desc->uinfo.auth.icv_truncbits/8;
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BUG_ON(ahp->icv_trunc_len > MAX_AH_AUTH_LEN);
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ahp->work_icv = kmalloc(ahp->icv_full_len, GFP_KERNEL);
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if (!ahp->work_icv)
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goto error;
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x->props.header_len = XFRM_ALIGN8(sizeof(struct ipv6_auth_hdr) + ahp->icv_trunc_len);
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if (x->props.mode)
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x->props.header_len += sizeof(struct ipv6hdr);
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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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if (ahp->work_icv)
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kfree(ahp->work_icv);
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if (ahp->tfm)
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crypto_free_tfm(ahp->tfm);
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kfree(ahp);
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}
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return -EINVAL;
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}
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static void ah6_destroy(struct xfrm_state *x)
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{
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struct ah_data *ahp = x->data;
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if (!ahp)
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return;
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if (ahp->work_icv) {
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kfree(ahp->work_icv);
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ahp->work_icv = NULL;
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}
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if (ahp->tfm) {
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crypto_free_tfm(ahp->tfm);
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ahp->tfm = NULL;
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}
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kfree(ahp);
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}
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static struct xfrm_type ah6_type =
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{
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.description = "AH6",
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.owner = THIS_MODULE,
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.proto = IPPROTO_AH,
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.init_state = ah6_init_state,
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.destructor = ah6_destroy,
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.input = ah6_input,
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.output = ah6_output
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};
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static struct inet6_protocol ah6_protocol = {
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.handler = xfrm6_rcv,
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.err_handler = ah6_err,
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.flags = INET6_PROTO_NOPOLICY,
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};
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static int __init ah6_init(void)
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{
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if (xfrm_register_type(&ah6_type, AF_INET6) < 0) {
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printk(KERN_INFO "ipv6 ah init: can't add xfrm type\n");
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return -EAGAIN;
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}
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if (inet6_add_protocol(&ah6_protocol, IPPROTO_AH) < 0) {
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printk(KERN_INFO "ipv6 ah init: can't add protocol\n");
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xfrm_unregister_type(&ah6_type, AF_INET6);
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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 ah6_fini(void)
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{
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if (inet6_del_protocol(&ah6_protocol, IPPROTO_AH) < 0)
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printk(KERN_INFO "ipv6 ah close: can't remove protocol\n");
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if (xfrm_unregister_type(&ah6_type, AF_INET6) < 0)
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printk(KERN_INFO "ipv6 ah close: can't remove xfrm type\n");
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}
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module_init(ah6_init);
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module_exit(ah6_fini);
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MODULE_LICENSE("GPL");
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