udpencap.c

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    1 /*-
    2  * Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  *
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 #include "opt_inet.h"
   31 #include "opt_ipsec.h"
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/kernel.h>
   36 #include <sys/lock.h>
   37 #include <sys/mbuf.h>
   38 #include <sys/protosw.h>
   39 #include <sys/socket.h>
   40 #include <sys/sockopt.h>
   41 #include <sys/sysctl.h>
   42 
   43 #include <netinet/in.h>
   44 #include <netinet/in_pcb.h>
   45 #include <netinet/in_systm.h>
   46 #include <netinet/ip.h>
   47 #include <netinet/ip_var.h>
   48 #include <netinet/tcp.h>
   49 #include <netinet/udp.h>
   50 #include <netinet/udp_var.h>
   51 
   52 #include <net/vnet.h>
   53 
   54 #include <netipsec/ipsec.h>
   55 #include <netipsec/esp.h>
   56 #include <netipsec/esp_var.h>
   57 #include <netipsec/xform.h>
   58 
   59 #include <netipsec/key.h>
   60 #include <netipsec/key_debug.h>
   61 #include <netipsec/ipsec_support.h>
   62 #include <machine/in_cksum.h>
   63 
   64 /*
   65  * Handle UDP_ENCAP socket option. Always return with released INP_WLOCK.
   66  */
   67 int
   68 udp_ipsec_pcbctl(struct inpcb *inp, struct sockopt *sopt)
   69 {
   70         struct udpcb *up;
   71         int error, optval;
   72 
   73         INP_WLOCK_ASSERT(inp);
   74         if (sopt->sopt_name != UDP_ENCAP) {
   75                 INP_WUNLOCK(inp);
   76                 return (ENOPROTOOPT);
   77         }
   78 
   79         up = intoudpcb(inp);
   80         if (sopt->sopt_dir == SOPT_GET) {
   81                 if (up->u_flags & UF_ESPINUDP)
   82                         optval = UDP_ENCAP_ESPINUDP;
   83                 else
   84                         optval = 0;
   85                 INP_WUNLOCK(inp);
   86                 return (sooptcopyout(sopt, &optval, sizeof(optval)));
   87         }
   88         INP_WUNLOCK(inp);
   89 
   90         error = sooptcopyin(sopt, &optval, sizeof(optval), sizeof(optval));
   91         if (error != 0)
   92                 return (error);
   93 
   94         INP_WLOCK(inp);
   95         switch (optval) {
   96         case 0:
   97                 up->u_flags &= ~UF_ESPINUDP;
   98                 break;
   99         case UDP_ENCAP_ESPINUDP:
  100                 up->u_flags |= UF_ESPINUDP;
  101                 break;
  102         default:
  103                 error = EINVAL;
  104         }
  105         INP_WUNLOCK(inp);
  106         return (error);
  107 }
  108 
  109 /*
  110  * Potentially decap ESP in UDP frame.  Check for an ESP header.
  111  * If present, strip the UDP header and push the result through IPSec.
  112  *
  113  * Returns error if mbuf consumed and/or processed, otherwise 0.
  114  */
  115 int
  116 udp_ipsec_input(struct mbuf *m, int off, int af)
  117 {
  118         union sockaddr_union dst;
  119         struct secasvar *sav;
  120         struct udphdr *udp;
  121         struct ip *ip;
  122         uint32_t spi;
  123         int hlen;
  124 
  125         /*
  126          * Just return if packet doesn't have enough data.
  127          * We need at least [IP header + UDP header + ESP header].
  128          * NAT-Keepalive packet has only one byte of payload, so it
  129          * by default will not be processed.
  130          */
  131         if (m->m_pkthdr.len < off + sizeof(struct esp))
  132                 return (0);
  133 
  134         m_copydata(m, off, sizeof(uint32_t), (caddr_t)&spi);
  135         if (spi == 0)   /* Non-ESP marker. */
  136                 return (0);
  137 
  138         /*
  139          * Find SA and check that it is configured for UDP
  140          * encapsulation.
  141          */
  142         bzero(&dst, sizeof(dst));
  143         dst.sa.sa_family = af;
  144         switch (af) {
  145 #ifdef INET
  146         case AF_INET:
  147                 dst.sin.sin_len = sizeof(struct sockaddr_in);
  148                 ip = mtod(m, struct ip *);
  149                 ip->ip_p = IPPROTO_ESP;
  150                 off = offsetof(struct ip, ip_p);
  151                 hlen = ip->ip_hl << 2;
  152                 dst.sin.sin_addr = ip->ip_dst;
  153                 break;
  154 #endif
  155 #ifdef INET6
  156         case AF_INET6:
  157                 /* Not yet */
  158                 /* FALLTHROUGH */
  159 #endif
  160         default:
  161                 ESPSTAT_INC(esps_nopf);
  162                 m_freem(m);
  163                 return (EPFNOSUPPORT);
  164         }
  165 
  166         sav = key_allocsa(&dst, IPPROTO_ESP, spi);
  167         if (sav == NULL) {
  168                 ESPSTAT_INC(esps_notdb);
  169                 m_freem(m);
  170                 return (ENOENT);
  171         }
  172         udp = mtodo(m, hlen);
  173         if (sav->natt == NULL ||
  174             sav->natt->sport != udp->uh_sport ||
  175             sav->natt->dport != udp->uh_dport) {
  176                 /* XXXAE: should we check source address? */
  177                 ESPSTAT_INC(esps_notdb);
  178                 key_freesav(&sav);
  179                 m_freem(m);
  180                 return (ENOENT);
  181         }
  182         /*
  183          * Remove the UDP header
  184          * Before:
  185          *   <--- off --->
  186          *   +----+------+-----+
  187          *   | IP |  UDP | ESP |
  188          *   +----+------+-----+
  189          *        <-skip->
  190          * After:
  191          *          +----+-----+
  192          *          | IP | ESP |
  193          *          +----+-----+
  194          *   <-skip->
  195          */
  196         m_striphdr(m, hlen, sizeof(*udp));
  197         /*
  198          * We cannot yet update the cksums so clear any h/w cksum flags
  199          * as they are no longer valid.
  200          */
  201         if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID)
  202                 m->m_pkthdr.csum_flags &= ~(CSUM_DATA_VALID | CSUM_PSEUDO_HDR);
  203         /*
  204          * We can update ip_len and ip_sum here, but ipsec4_input_cb()
  205          * will do this anyway, so don't touch them here.
  206          */
  207         ESPSTAT_INC(esps_input);
  208         (*sav->tdb_xform->xf_input)(m, sav, hlen, off);
  209         return (EINPROGRESS);   /* Consumed by IPsec. */
  210 }
  211 
  212 int
  213 udp_ipsec_output(struct mbuf *m, struct secasvar *sav)
  214 {
  215         struct udphdr *udp;
  216         struct mbuf *n;
  217         struct ip *ip;
  218         int hlen, off;
  219 
  220         IPSEC_ASSERT(sav->natt != NULL, ("UDP encapsulation isn't required."));
  221 
  222         if (sav->sah->saidx.dst.sa.sa_family == AF_INET6)
  223                 return (EAFNOSUPPORT);
  224 
  225         ip = mtod(m, struct ip *);
  226         hlen = ip->ip_hl << 2;
  227         n = m_makespace(m, hlen, sizeof(*udp), &off);
  228         if (n == NULL) {
  229                 DPRINTF(("%s: m_makespace for udphdr failed\n", __func__));
  230                 return (ENOBUFS);
  231         }
  232 
  233         udp = mtodo(n, off);
  234         udp->uh_dport = sav->natt->dport;
  235         udp->uh_sport = sav->natt->sport;
  236         udp->uh_sum = 0;
  237         udp->uh_ulen = htons(m->m_pkthdr.len - hlen);
  238 
  239         ip = mtod(m, struct ip *);
  240         ip->ip_len = htons(m->m_pkthdr.len);
  241         ip->ip_p = IPPROTO_UDP;
  242         return (0);
  243 }
  244 
  245 void
  246 udp_ipsec_adjust_cksum(struct mbuf *m, struct secasvar *sav, int proto,
  247     int skip)
  248 {
  249         struct ip *ip;
  250         uint16_t cksum, off;
  251 
  252         IPSEC_ASSERT(sav->natt != NULL, ("NAT-T isn't required"));
  253         IPSEC_ASSERT(proto == IPPROTO_UDP || proto == IPPROTO_TCP,
  254             ("unexpected protocol %u", proto));
  255 
  256         if (proto == IPPROTO_UDP)
  257                 off = offsetof(struct udphdr, uh_sum);
  258         else
  259                 off = offsetof(struct tcphdr, th_sum);
  260 
  261         if (V_natt_cksum_policy == 0) { /* auto */
  262                 if (sav->natt->cksum != 0) {
  263                         /* Incrementally recompute. */
  264                         m_copydata(m, skip + off, sizeof(cksum),
  265                             (caddr_t)&cksum);
  266                         /* Do not adjust UDP checksum if it is zero. */
  267                         if (proto == IPPROTO_UDP && cksum == 0)
  268                                 return;
  269                         cksum = in_addword(cksum, sav->natt->cksum);
  270                 } else {
  271                         /* No OA from IKEd. */
  272                         if (proto == IPPROTO_TCP) {
  273                                 /* Ignore for TCP. */
  274                                 m->m_pkthdr.csum_data = 0xffff;
  275                                 m->m_pkthdr.csum_flags |= (CSUM_DATA_VALID |
  276                                     CSUM_PSEUDO_HDR);
  277                                 return;
  278                         }
  279                         cksum = 0; /* Reset for UDP. */
  280                 }
  281                 m_copyback(m, skip + off, sizeof(cksum), (caddr_t)&cksum);
  282         } else { /* Fully recompute */
  283                 ip = mtod(m, struct ip *);
  284                 cksum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
  285                     htons(m->m_pkthdr.len - skip + proto));
  286                 m_copyback(m, skip + off, sizeof(cksum), (caddr_t)&cksum);
  287                 m->m_pkthdr.csum_flags =
  288                     (proto == IPPROTO_UDP) ? CSUM_UDP: CSUM_TCP;
  289                 m->m_pkthdr.csum_data = off;
  290                 in_delayed_cksum(m);
  291                 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  292         }
  293 }
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FreeBSD/Linux Kernel Cross Reference sys/netipsec/udpencap.c

FreeBSD/Linux Kernel Cross Reference
sys/netipsec/udpencap.c
