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

     /*      $FreeBSD$ */
     
     /*-
      * Copyright (c) 2003 Bruce M. Simpson <bms@spc.org>
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      *
     * 1. Redistributions of source code must retain the above copyright
     *   notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *   notice, this list of conditions and the following disclaimer in the
     *   documentation and/or other materials provided with the distribution.
     * 3. The name of the author may not be used to endorse or promote products
     *   derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    /* TCP MD5 Signature Option (RFC2385) */
    #include "opt_inet.h"
    #include "opt_inet6.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/mbuf.h>
    #include <sys/lock.h>
    #include <sys/socket.h>
    #include <sys/kernel.h>
    #include <sys/protosw.h>
    #include <sys/sysctl.h>
    
    #include <netinet/in.h>
    #include <netinet/in_systm.h>
    #include <netinet/ip.h>
    #include <netinet/ip_var.h>
    #include <netinet/tcp.h>
    #include <netinet/tcp_var.h>
    
    #include <net/vnet.h>
    
    #include <netipsec/ipsec.h>
    #include <netipsec/xform.h>
    
    #ifdef INET6
    #include <netinet/ip6.h>
    #include <netipsec/ipsec6.h>
    #endif
    
    #include <netipsec/key.h>
    #include <netipsec/key_debug.h>
    
    /*
     * Initialize a TCP-MD5 SA. Called when the SA is being set up.
     *
     * We don't need to set up the tdb prefixed fields, as we don't use the
     * opencrypto code; we just perform a key length check.
     *
     * XXX: Currently we only allow a single 'magic' SPI to be used.
     *
     * This allows per-host granularity without affecting the userland
     * interface, which is a simple socket option toggle switch,
     * TCP_SIGNATURE_ENABLE.
     *
     * To allow per-service granularity requires that we have a means
     * of mapping port to SPI. The mandated way of doing this is to
     * use SPD entries to specify packet flows which get the TCP-MD5
     * treatment, however the code to do this is currently unstable
     * and unsuitable for production use.
     *
     * Therefore we use this compromise in the meantime.
     */
    static int
    tcpsignature_init(struct secasvar *sav, struct xformsw *xsp)
    {
            int keylen;
    
            if (sav->spi != htonl(TCP_SIG_SPI)) {
                    DPRINTF(("%s: SPI must be TCP_SIG_SPI (0x1000)\n",
                        __func__));
                    return (EINVAL);
            }
            if (sav->alg_auth != SADB_X_AALG_TCP_MD5) {
                    DPRINTF(("%s: unsupported authentication algorithm %u\n",
                        __func__, sav->alg_auth));
                    return (EINVAL);
            }
            if (sav->key_auth == NULL) {
                    DPRINTF(("%s: no authentication key present\n", __func__));
                   return (EINVAL);
           }
           keylen = _KEYLEN(sav->key_auth);
           if ((keylen < TCP_KEYLEN_MIN) || (keylen > TCP_KEYLEN_MAX)) {
                   DPRINTF(("%s: invalid key length %u\n", __func__, keylen));
                   return (EINVAL);
           }
   
           return (0);
   }
   
   /*
    * Paranoia.
    *
    * Called when the SA is deleted.
    */
   static int
   tcpsignature_zeroize(struct secasvar *sav)
   {
   
           if (sav->key_auth)
                   bzero(sav->key_auth->key_data, _KEYLEN(sav->key_auth));
   
           sav->tdb_cryptoid = 0;
           sav->tdb_authalgxform = NULL;
           sav->tdb_xform = NULL;
   
           return (0);
   }
   
   /*
    * Verify that an input packet passes authentication.
    * Called from the ipsec layer.
    * We do this from within tcp itself, so this routine is just a stub.
    */
   static int
   tcpsignature_input(struct mbuf *m, struct secasvar *sav, int skip,
       int protoff)
   {
   
           return (0);
   }
   
   /*
    * Prepend the authentication header.
    * Called from the ipsec layer.
    * We do this from within tcp itself, so this routine is just a stub.
    */
   static int
   tcpsignature_output(struct mbuf *m, struct ipsecrequest *isr,
       struct mbuf **mp, int skip, int protoff)
   {
   
           return (EINVAL);
   }
   
   static struct xformsw tcpsignature_xformsw = {
           XF_TCPSIGNATURE,        XFT_AUTH,               "TCPMD5",
           tcpsignature_init,      tcpsignature_zeroize,
           tcpsignature_input,     tcpsignature_output
   };
   
   static void
   tcpsignature_attach(void)
   {
   
           xform_register(&tcpsignature_xformsw);
   }
   
   SYSINIT(tcpsignature_xform_init, SI_SUB_DRIVERS, SI_ORDER_FIRST,
       tcpsignature_attach, NULL);

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