/*      $NetBSD: aes_ccm_mbuf.c,v 1.1 2020/07/25 22:15:55 riastradh Exp $       */

/*-
* Copyright (c) 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(1, "$NetBSD: aes_ccm_mbuf.c,v 1.1 2020/07/25 22:15:55 riastradh Exp $");

#include <sys/types.h>

#include <sys/mbuf.h>

#include <lib/libkern/libkern.h>

#include <crypto/aes/aes_ccm.h>
#include <crypto/aes/aes_ccm_mbuf.h>

void
aes_ccm_enc_mbuf(struct aes_ccm *C, struct mbuf *m, size_t off, size_t len,
   void *tag)
{
       uint8_t *p;
       size_t seglen;

       while (off >= m->m_len) {
               KASSERT(m->m_next);
               m = m->m_next;
               off -= m->m_len;
       }

       for (; len > 0; m = m->m_next, off = 0, len -= seglen) {
               KASSERT(m->m_len >= off);
               p = mtod(m, uint8_t *) + off;
               seglen = MIN(m->m_len - off, len);
               aes_ccm_enc(C, p, p, seglen);
       }

       aes_ccm_tag(C, tag);
}

int
aes_ccm_dec_mbuf(struct aes_ccm *C, struct mbuf *m0, size_t off0, size_t len0,
   const void *tag)
{
       struct mbuf *m;
       size_t off, len;
       uint8_t *p;
       size_t seglen;

       while (off0 >= m0->m_len) {
               KASSERT(m0->m_next);
               m0 = m0->m_next;
               off0 -= m0->m_len;
       }

       for (m = m0, off = off0, len = len0;
            len > 0;
            m = m->m_next, off = 0, len -= seglen) {
               KASSERT(m->m_len >= off);
               p = mtod(m, uint8_t *) + off;
               seglen = MIN(m->m_len - off, len);
               aes_ccm_dec(C, p, p, seglen);
       }

       if (aes_ccm_verify(C, tag))
               return 1;

       /*
        * Verification failed.  Zero the mbuf so we don't accidentally
        * leak anything about it.
        */
       for (m = m0, off = off0, len = len0;
            len > 0;
            m = m->m_next, off = 0, len -= seglen) {
               KASSERT(m->m_len >= off);
               p = mtod(m, uint8_t *) + off;
               seglen = MIN(m->m_len - off, len);
               memset(p, 0, seglen);
       }

       return 0;
}