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      1 /*	$NetBSD: aes_ccm_mbuf.c,v 1.1 2020/07/25 22:15:55 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2020 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 __KERNEL_RCSID(1, "$NetBSD: aes_ccm_mbuf.c,v 1.1 2020/07/25 22:15:55 riastradh Exp $");
     31 
     32 #include <sys/types.h>
     33 
     34 #include <sys/mbuf.h>
     35 
     36 #include <lib/libkern/libkern.h>
     37 
     38 #include <crypto/aes/aes_ccm.h>
     39 #include <crypto/aes/aes_ccm_mbuf.h>
     40 
     41 void
     42 aes_ccm_enc_mbuf(struct aes_ccm *C, struct mbuf *m, size_t off, size_t len,
     43     void *tag)
     44 {
     45 	uint8_t *p;
     46 	size_t seglen;
     47 
     48 	while (off >= m->m_len) {
     49 		KASSERT(m->m_next);
     50 		m = m->m_next;
     51 		off -= m->m_len;
     52 	}
     53 
     54 	for (; len > 0; m = m->m_next, off = 0, len -= seglen) {
     55 		KASSERT(m->m_len >= off);
     56 		p = mtod(m, uint8_t *) + off;
     57 		seglen = MIN(m->m_len - off, len);
     58 		aes_ccm_enc(C, p, p, seglen);
     59 	}
     60 
     61 	aes_ccm_tag(C, tag);
     62 }
     63 
     64 int
     65 aes_ccm_dec_mbuf(struct aes_ccm *C, struct mbuf *m0, size_t off0, size_t len0,
     66     const void *tag)
     67 {
     68 	struct mbuf *m;
     69 	size_t off, len;
     70 	uint8_t *p;
     71 	size_t seglen;
     72 
     73 	while (off0 >= m0->m_len) {
     74 		KASSERT(m0->m_next);
     75 		m0 = m0->m_next;
     76 		off0 -= m0->m_len;
     77 	}
     78 
     79 	for (m = m0, off = off0, len = len0;
     80 	     len > 0;
     81 	     m = m->m_next, off = 0, len -= seglen) {
     82 		KASSERT(m->m_len >= off);
     83 		p = mtod(m, uint8_t *) + off;
     84 		seglen = MIN(m->m_len - off, len);
     85 		aes_ccm_dec(C, p, p, seglen);
     86 	}
     87 
     88 	if (aes_ccm_verify(C, tag))
     89 		return 1;
     90 
     91 	/*
     92 	 * Verification failed.  Zero the mbuf so we don't accidentally
     93 	 * leak anything about it.
     94 	 */
     95 	for (m = m0, off = off0, len = len0;
     96 	     len > 0;
     97 	     m = m->m_next, off = 0, len -= seglen) {
     98 		KASSERT(m->m_len >= off);
     99 		p = mtod(m, uint8_t *) + off;
    100 		seglen = MIN(m->m_len - off, len);
    101 		memset(p, 0, seglen);
    102 	}
    103 
    104 	return 0;
    105 }
    106