/* $NetBSD: ipsec_mbuf.c,v 1.30 2018/12/22 13:11:38 maxv Exp $ */
/*
* Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting
* 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 AUTHOR 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 AUTHOR 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.
*
* $FreeBSD: sys/netipsec/ipsec_mbuf.c,v 1.5.2.2 2003/03/28 20:32:53 sam Exp $
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ipsec_mbuf.c,v 1.30 2018/12/22 13:11:38 maxv Exp $");
/*
* IPsec-specific mbuf routines.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <netipsec/ipsec.h>
#include <netipsec/ipsec_var.h>
#include <netipsec/ipsec_private.h>
/*
* Create a writable copy of the mbuf chain. While doing this
* we compact the chain with a goal of producing a chain with
* at most two mbufs. The second mbuf in this chain is likely
* to be a cluster. The primary purpose of this work is to create
* a writable packet for encryption, compression, etc. The
* secondary goal is to linearize the data so the data can be
* passed to crypto hardware in the most efficient manner possible.
*/
struct mbuf *
m_clone(struct mbuf *m0)
{
struct mbuf *m, *mprev;
struct mbuf *n, *mfirst, *mlast;
int len, off;
KASSERT(m0 != NULL);
mprev = NULL;
for (m = m0; m != NULL; m = mprev->m_next) {
/*
* Regular mbufs are ignored unless there's a cluster
* in front of it that we can use to coalesce.
*/
if ((m->m_flags & M_EXT) == 0) {
if (mprev && (mprev->m_flags & M_EXT) &&
m->m_len <= M_TRAILINGSPACE(mprev)) {
memcpy(mtod(mprev, char *) + mprev->m_len,
mtod(m, char *), m->m_len);
mprev->m_len += m->m_len;
mprev->m_next = m_free(m);
IPSEC_STATINC(IPSEC_STAT_MBCOALESCED);
} else {
mprev = m;
}
continue;
}
/*
* Writable mbufs are left alone.
*/
if (!M_READONLY(m)) {
mprev = m;
continue;
}
/*
* Not writable, replace with a copy or coalesce with
* the previous mbuf if possible (since we have to copy
* it anyway, we try to reduce the number of mbufs and
* clusters so that future work is easier).
*/
/* We only coalesce into a cluster. */
if (mprev != NULL && (mprev->m_flags & M_EXT) &&
m->m_len <= M_TRAILINGSPACE(mprev)) {
memcpy(mtod(mprev, char *) + mprev->m_len,
mtod(m, char *), m->m_len);
mprev->m_len += m->m_len;
mprev->m_next = m_free(m);
IPSEC_STATINC(IPSEC_STAT_CLCOALESCED);
continue;
}
/*
* Allocate new space to hold the copy...
*/
if (mprev == NULL && (m->m_flags & M_PKTHDR)) {
MGETHDR(n, M_DONTWAIT, m->m_type);
if (n == NULL) {
m_freem(m0);
return NULL;
}
m_move_pkthdr(n, m);
MCLGET(n, M_DONTWAIT);
if ((n->m_flags & M_EXT) == 0) {
m_free(n);
m_freem(m0);
return NULL;
}
} else {
n = m_getcl(M_DONTWAIT, m->m_type, m->m_flags);
if (n == NULL) {
m_freem(m0);
return NULL;
}
}
/*
* ... and copy the data. We deal with jumbo mbufs
* (i.e. m_len > MCLBYTES) by splitting them into
* clusters. We could just malloc a buffer and make
* it external but too many device drivers don't know
* how to break up the non-contiguous memory when
* doing DMA.
*/
len = m->m_len;
off = 0;
mfirst = n;
mlast = NULL;
for (;;) {
const int cc = uimin(len, MCLBYTES);
memcpy(mtod(n, char *), mtod(m, char *) + off, cc);
n->m_len = cc;
if (mlast != NULL)
mlast->m_next = n;
mlast = n;
IPSEC_STATINC(IPSEC_STAT_CLCOPIED);
len -= cc;
if (len <= 0)
break;
off += cc;
n = m_getcl(M_DONTWAIT, m->m_type, m->m_flags);
if (n == NULL) {
m_freem(mfirst);
m_freem(m0);
return NULL;
}
}
n->m_next = m->m_next;
if (mprev == NULL)
m0 = mfirst; /* new head of chain */
else
mprev->m_next = mfirst; /* replace old mbuf */
m_free(m); /* release old mbuf */
mprev = mfirst;
}
return m0;
}
/*
* Make space for a new header of length hlen at skip bytes
* into the packet. When doing this we allocate new mbufs only
* when absolutely necessary. The mbuf where the new header
* is to go is returned together with an offset into the mbuf.
* If NULL is returned then the mbuf chain may have been modified;
* the caller is assumed to always free the chain.
*/
struct mbuf *
m_makespace(struct mbuf *m0, int skip, int hlen, int *off)
{
struct mbuf *m;
unsigned remain;
KASSERT(m0 != NULL);
KASSERT(m0->m_flags & M_PKTHDR);
KASSERTMSG(hlen < MHLEN, "hlen too big: %u", hlen);
for (m = m0; m && skip > m->m_len; m = m->m_next)
skip -= m->m_len;
if (m == NULL)
return NULL;
/*
* At this point skip is the offset into the mbuf m
* where the new header should be placed. Figure out
* if there's space to insert the new header. If so,
* and copying the remainder makes sense then do so.
* Otherwise insert a new mbuf in the chain, splitting
* the contents of m as needed.
*/
remain = m->m_len - skip; /* data to move */
if (hlen > M_TRAILINGSPACE(m)) {
struct mbuf *n0, *n, **np;
int todo, len, done, alloc;
n0 = NULL;
np = &n0;
alloc = 0;
done = 0;
todo = remain;
while (todo > 0) {
if (todo > MHLEN) {
n = m_getcl(M_DONTWAIT, m->m_type, 0);
len = MCLBYTES;
} else {
n = m_get(M_DONTWAIT, m->m_type);
len = MHLEN;
}
if (n == NULL) {
m_freem(n0);
return NULL;
}
*np = n;
np = &n->m_next;
alloc++;
len = uimin(todo, len);
memcpy(n->m_data, mtod(m, char *) + skip + done, len);
n->m_len = len;
done += len;
todo -= len;
}
if (hlen <= M_TRAILINGSPACE(m) + remain) {
m->m_len = skip + hlen;
*off = skip;
if (n0 != NULL) {
*np = m->m_next;
m->m_next = n0;
}
} else {
n = m_get(M_DONTWAIT, m->m_type);
if (n == NULL) {
m_freem(n0);
return NULL;
}
alloc++;
if ((n->m_next = n0) == NULL)
np = &n->m_next;
n0 = n;
*np = m->m_next;
m->m_next = n0;
n->m_len = hlen;
m->m_len = skip;
m = n; /* header is at front ... */
*off = 0; /* ... of new mbuf */
}
IPSEC_STATADD(IPSEC_STAT_MBINSERTED, alloc);
} else {
/*
* Copy the remainder to the back of the mbuf
* so there's space to write the new header.
*/
/* XXX can this be memcpy? does it handle overlap? */
memmove(mtod(m, char *) + skip + hlen,
mtod(m, char *) + skip, remain);
m->m_len += hlen;
*off = skip;
}
m0->m_pkthdr.len += hlen; /* adjust packet length */
return m;
}
/*
* m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
* length is updated, and a pointer to the first byte of the padding
* (which is guaranteed to be all in one mbuf) is returned.
*/
void *
m_pad(struct mbuf *m, int n)
{
register struct mbuf *m0, *m1;
register int len, pad;
void *retval;
if (__predict_false(n > MLEN)) {
panic("%s: %d > MLEN", __func__, n);
}
KASSERT(m->m_flags & M_PKTHDR);
len = m->m_pkthdr.len;
pad = n;
m0 = m;
while (m0->m_len < len) {
KASSERTMSG(m0->m_next != NULL,
"m0 null, len %u m_len %u", len, m0->m_len);
len -= m0->m_len;
m0 = m0->m_next;
}
if (m0->m_len != len) {
IPSECLOG(LOG_DEBUG,
"length mismatch (should be %d instead of %d)\n",
m->m_pkthdr.len, m->m_pkthdr.len + m0->m_len - len);
m_freem(m);
return NULL;
}
/* Check for zero-length trailing mbufs, and find the last one. */
for (m1 = m0; m1->m_next; m1 = m1->m_next) {
if (m1->m_next->m_len != 0) {
IPSECLOG(LOG_DEBUG,
"length mismatch (should be %d instead of %d)\n",
m->m_pkthdr.len,
m->m_pkthdr.len + m1->m_next->m_len);
m_freem(m);
return NULL;
}
m0 = m1->m_next;
}
if (pad > M_TRAILINGSPACE(m0)) {
/* Add an mbuf to the chain. */
MGET(m1, M_DONTWAIT, MT_DATA);
if (m1 == NULL) {
m_freem(m);
IPSECLOG(LOG_DEBUG, "unable to get extra mbuf\n");
return NULL;
}
m0->m_next = m1;
m0 = m1;
m0->m_len = 0;
}
retval = m0->m_data + m0->m_len;
m0->m_len += pad;
m->m_pkthdr.len += pad;
return retval;
}
/*
* Remove hlen data at offset skip in the packet. This is used by
* the protocols strip protocol headers and associated data (e.g. IV,
* authenticator) on input.
*/
int
m_striphdr(struct mbuf *m, int skip, int hlen)
{
struct mbuf *m1;
int roff;
KASSERT(m->m_flags & M_PKTHDR);
/* Find beginning of header */
m1 = m_getptr(m, skip, &roff);
if (m1 == NULL)
return EINVAL;
/* Remove the header and associated data from the mbuf. */
if (roff == 0) {
/* The header was at the beginning of the mbuf */
IPSEC_STATINC(IPSEC_STAT_INPUT_FRONT);
m_adj(m1, hlen);
if (m1 != m)
m->m_pkthdr.len -= hlen;
} else if (roff + hlen >= m1->m_len) {
struct mbuf *mo;
int adjlen;
/*
* Part or all of the header is at the end of this mbuf,
* so first let's remove the remainder of the header from
* the beginning of the remainder of the mbuf chain, if any.
*/
IPSEC_STATINC(IPSEC_STAT_INPUT_END);
if (roff + hlen > m1->m_len) {
adjlen = roff + hlen - m1->m_len;
/* Adjust the next mbuf by the remainder */
m_adj(m1->m_next, adjlen);
/* The second mbuf is guaranteed not to have a pkthdr... */
m->m_pkthdr.len -= adjlen;
}
/* Now, let's unlink the mbuf chain for a second...*/
mo = m1->m_next;
m1->m_next = NULL;
/* ...and trim the end of the first part of the chain...sick */
adjlen = m1->m_len - roff;
m_adj(m1, -adjlen);
if (m1 != m)
m->m_pkthdr.len -= adjlen;
/* Finally, let's relink */
m1->m_next = mo;
} else {
/*
* The header lies in the "middle" of the mbuf; copy
* the remainder of the mbuf down over the header.
*/
IPSEC_STATINC(IPSEC_STAT_INPUT_MIDDLE);
memmove(mtod(m1, u_char *) + roff,
mtod(m1, u_char *) + roff + hlen,
m1->m_len - (roff + hlen));
m1->m_len -= hlen;
m->m_pkthdr.len -= hlen;
}
return 0;
}