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freebsd-dev/sys/kern/uipc_mbuf.c
Sam Leffler 59d8b31002 change m_adj to reclaim unused mbufs instead of zero'ing m_len 
when trim'ing space off the back of a chain; this is indirect
solution to a potential null ptr deref

Noticed by:	Coverity Prevent analysis tool (null ptr deref)
Reviewed by:	dg, rwatson
2005-02-24 00:40:33 +00:00

1333 lines
31 KiB
C
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/*-
* Copyright (c) 1982, 1986, 1988, 1991, 1993
* The Regents of the University of California. 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_mac.h"
#include "opt_param.h"
#include "opt_mbuf_stress_test.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mac.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/sysctl.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/uio.h>
int max_linkhdr;
int max_protohdr;
int max_hdr;
int max_datalen;
#ifdef MBUF_STRESS_TEST
int m_defragpackets;
int m_defragbytes;
int m_defraguseless;
int m_defragfailure;
int m_defragrandomfailures;
#endif
/*
* sysctl(8) exported objects
*/
SYSCTL_DECL(_kern_ipc);
SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW,
&max_linkhdr, 0, "");
SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW,
&max_protohdr, 0, "");
SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, "");
SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW,
&max_datalen, 0, "");
#ifdef MBUF_STRESS_TEST
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD,
&m_defragpackets, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD,
&m_defragbytes, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD,
&m_defraguseless, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD,
&m_defragfailure, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW,
&m_defragrandomfailures, 0, "");
#endif
/*
* Malloc-type for external ext_buf ref counts.
*/
static MALLOC_DEFINE(M_MBUF, "mbextcnt", "mbuf external ref counts");
/*
* Allocate a given length worth of mbufs and/or clusters (whatever fits
* best) and return a pointer to the top of the allocated chain. If an
* existing mbuf chain is provided, then we will append the new chain
* to the existing one but still return the top of the newly allocated
* chain.
*/
struct mbuf *
m_getm(struct mbuf *m, int len, int how, short type)
{
struct mbuf *mb, *top, *cur, *mtail;
int num, rem;
int i;
KASSERT(len >= 0, ("m_getm(): len is < 0"));
/* If m != NULL, we will append to the end of that chain. */
if (m != NULL)
for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next);
else
mtail = NULL;
/*
* Calculate how many mbufs+clusters ("packets") we need and how much
* leftover there is after that and allocate the first mbuf+cluster
* if required.
*/
num = len / MCLBYTES;
rem = len % MCLBYTES;
top = cur = NULL;
if (num > 0) {
if ((top = cur = m_getcl(how, type, 0)) == NULL)
goto failed;
top->m_len = 0;
}
num--;
for (i = 0; i < num; i++) {
mb = m_getcl(how, type, 0);
if (mb == NULL)
goto failed;
mb->m_len = 0;
cur = (cur->m_next = mb);
}
if (rem > 0) {
mb = (rem > MINCLSIZE) ?
m_getcl(how, type, 0) : m_get(how, type);
if (mb == NULL)
goto failed;
mb->m_len = 0;
if (cur == NULL)
top = mb;
else
cur->m_next = mb;
}
if (mtail != NULL)
mtail->m_next = top;
return top;
failed:
if (top != NULL)
m_freem(top);
return NULL;
}
/*
* Free an entire chain of mbufs and associated external buffers, if
* applicable.
*/
void
m_freem(struct mbuf *mb)
{
while (mb != NULL)
mb = m_free(mb);
}
/*-
* Configure a provided mbuf to refer to the provided external storage
* buffer and setup a reference count for said buffer. If the setting
* up of the reference count fails, the M_EXT bit will not be set. If
* successfull, the M_EXT bit is set in the mbuf's flags.
*
* Arguments:
* mb The existing mbuf to which to attach the provided buffer.
* buf The address of the provided external storage buffer.
* size The size of the provided buffer.
* freef A pointer to a routine that is responsible for freeing the
* provided external storage buffer.
* args A pointer to an argument structure (of any type) to be passed
* to the provided freef routine (may be NULL).
* flags Any other flags to be passed to the provided mbuf.
* type The type that the external storage buffer should be
* labeled with.
*
* Returns:
* Nothing.
*/
void
m_extadd(struct mbuf *mb, caddr_t buf, u_int size,
void (*freef)(void *, void *), void *args, int flags, int type)
{
u_int *ref_cnt = NULL;
/* XXX Shouldn't be adding EXT_CLUSTER with this API */
if (type == EXT_CLUSTER)
ref_cnt = (u_int *)uma_find_refcnt(zone_clust,
mb->m_ext.ext_buf);
else if (type == EXT_EXTREF)
ref_cnt = mb->m_ext.ref_cnt;
mb->m_ext.ref_cnt = (ref_cnt == NULL) ?
malloc(sizeof(u_int), M_MBUF, M_NOWAIT) : (u_int *)ref_cnt;
if (mb->m_ext.ref_cnt != NULL) {
*(mb->m_ext.ref_cnt) = 1;
mb->m_flags |= (M_EXT | flags);
mb->m_ext.ext_buf = buf;
mb->m_data = mb->m_ext.ext_buf;
mb->m_ext.ext_size = size;
mb->m_ext.ext_free = freef;
mb->m_ext.ext_args = args;
mb->m_ext.ext_type = type;
}
}
/*
* Non-directly-exported function to clean up after mbufs with M_EXT
* storage attached to them if the reference count hits 0.
*/
void
mb_free_ext(struct mbuf *m)
{
u_int cnt;
int dofree;
/* Account for lazy ref count assign. */
if (m->m_ext.ref_cnt == NULL)
dofree = 1;
else
dofree = 0;
/*
* This is tricky. We need to make sure to decrement the
* refcount in a safe way but to also clean up if we're the
* last reference. This method seems to do it without race.
*/
while (dofree == 0) {
cnt = *(m->m_ext.ref_cnt);
if (atomic_cmpset_int(m->m_ext.ref_cnt, cnt, cnt - 1)) {
if (cnt == 1)
dofree = 1;
break;
}
}
if (dofree) {
/*
* Do the free, should be safe.
*/
if (m->m_ext.ext_type == EXT_PACKET) {
uma_zfree(zone_pack, m);
return;
} else if (m->m_ext.ext_type == EXT_CLUSTER) {
uma_zfree(zone_clust, m->m_ext.ext_buf);
m->m_ext.ext_buf = NULL;
} else {
(*(m->m_ext.ext_free))(m->m_ext.ext_buf,
m->m_ext.ext_args);
if (m->m_ext.ext_type != EXT_EXTREF) {
if (m->m_ext.ref_cnt != NULL)
free(m->m_ext.ref_cnt, M_MBUF);
m->m_ext.ref_cnt = NULL;
}
m->m_ext.ext_buf = NULL;
}
}
uma_zfree(zone_mbuf, m);
}
/*
* "Move" mbuf pkthdr from "from" to "to".
* "from" must have M_PKTHDR set, and "to" must be empty.
*/
void
m_move_pkthdr(struct mbuf *to, struct mbuf *from)
{
#if 0
/* see below for why these are not enabled */
M_ASSERTPKTHDR(to);
/* Note: with MAC, this may not be a good assertion. */
KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags),
("m_move_pkthdr: to has tags"));
#endif
KASSERT((to->m_flags & M_EXT) == 0, ("m_move_pkthdr: to has cluster"));
#ifdef MAC
/*
* XXXMAC: It could be this should also occur for non-MAC?
*/
if (to->m_flags & M_PKTHDR)
m_tag_delete_chain(to, NULL);
#endif
to->m_flags = from->m_flags & M_COPYFLAGS;
to->m_data = to->m_pktdat;
to->m_pkthdr = from->m_pkthdr; /* especially tags */
SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */
from->m_flags &= ~M_PKTHDR;
}
/*
* Duplicate "from"'s mbuf pkthdr in "to".
* "from" must have M_PKTHDR set, and "to" must be empty.
* In particular, this does a deep copy of the packet tags.
*/
int
m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how)
{
#if 0
/*
* The mbuf allocator only initializes the pkthdr
* when the mbuf is allocated with MGETHDR. Many users
* (e.g. m_copy*, m_prepend) use MGET and then
* smash the pkthdr as needed causing these
* assertions to trip. For now just disable them.
*/
M_ASSERTPKTHDR(to);
/* Note: with MAC, this may not be a good assertion. */
KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags"));
#endif
MBUF_CHECKSLEEP(how);
#ifdef MAC
if (to->m_flags & M_PKTHDR)
m_tag_delete_chain(to, NULL);
#endif
to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
if ((to->m_flags & M_EXT) == 0)
to->m_data = to->m_pktdat;
to->m_pkthdr = from->m_pkthdr;
SLIST_INIT(&to->m_pkthdr.tags);
return (m_tag_copy_chain(to, from, MBTOM(how)));
}
/*
* Lesser-used path for M_PREPEND:
* allocate new mbuf to prepend to chain,
* copy junk along.
*/
struct mbuf *
m_prepend(struct mbuf *m, int len, int how)
{
struct mbuf *mn;
if (m->m_flags & M_PKTHDR)
MGETHDR(mn, how, m->m_type);
else
MGET(mn, how, m->m_type);
if (mn == NULL) {
m_freem(m);
return (NULL);
}
if (m->m_flags & M_PKTHDR)
M_MOVE_PKTHDR(mn, m);
mn->m_next = m;
m = mn;
if (len < MHLEN)
MH_ALIGN(m, len);
m->m_len = len;
return (m);
}
/*
* Make a copy of an mbuf chain starting "off0" bytes from the beginning,
* continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf.
* The wait parameter is a choice of M_TRYWAIT/M_DONTWAIT from caller.
* Note that the copy is read-only, because clusters are not copied,
* only their reference counts are incremented.
*/
struct mbuf *
m_copym(struct mbuf *m, int off0, int len, int wait)
{
struct mbuf *n, **np;
int off = off0;
struct mbuf *top;
int copyhdr = 0;
KASSERT(off >= 0, ("m_copym, negative off %d", off));
KASSERT(len >= 0, ("m_copym, negative len %d", len));
MBUF_CHECKSLEEP(wait);
if (off == 0 && m->m_flags & M_PKTHDR)
copyhdr = 1;
while (off > 0) {
KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
if (off < m->m_len)
break;
off -= m->m_len;
m = m->m_next;
}
np = &top;
top = 0;
while (len > 0) {
if (m == NULL) {
KASSERT(len == M_COPYALL,
("m_copym, length > size of mbuf chain"));
break;
}
if (copyhdr)
MGETHDR(n, wait, m->m_type);
else
MGET(n, wait, m->m_type);
*np = n;
if (n == NULL)
goto nospace;
if (copyhdr) {
if (!m_dup_pkthdr(n, m, wait))
goto nospace;
if (len == M_COPYALL)
n->m_pkthdr.len -= off0;
else
n->m_pkthdr.len = len;
copyhdr = 0;
}
n->m_len = min(len, m->m_len - off);
if (m->m_flags & M_EXT) {
n->m_data = m->m_data + off;
n->m_ext = m->m_ext;
n->m_flags |= M_EXT;
MEXT_ADD_REF(m);
n->m_ext.ref_cnt = m->m_ext.ref_cnt;
} else
bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
(u_int)n->m_len);
if (len != M_COPYALL)
len -= n->m_len;
off = 0;
m = m->m_next;
np = &n->m_next;
}
if (top == NULL)
mbstat.m_mcfail++; /* XXX: No consistency. */
return (top);
nospace:
m_freem(top);
mbstat.m_mcfail++; /* XXX: No consistency. */
return (NULL);
}
/*
* Copy an entire packet, including header (which must be present).
* An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
* Note that the copy is read-only, because clusters are not copied,
* only their reference counts are incremented.
* Preserve alignment of the first mbuf so if the creator has left
* some room at the beginning (e.g. for inserting protocol headers)
* the copies still have the room available.
*/
struct mbuf *
m_copypacket(struct mbuf *m, int how)
{
struct mbuf *top, *n, *o;
MBUF_CHECKSLEEP(how);
MGET(n, how, m->m_type);
top = n;
if (n == NULL)
goto nospace;
if (!m_dup_pkthdr(n, m, how))
goto nospace;
n->m_len = m->m_len;
if (m->m_flags & M_EXT) {
n->m_data = m->m_data;
n->m_ext = m->m_ext;
n->m_flags |= M_EXT;
MEXT_ADD_REF(m);
n->m_ext.ref_cnt = m->m_ext.ref_cnt;
} else {
n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat );
bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
}
m = m->m_next;
while (m) {
MGET(o, how, m->m_type);
if (o == NULL)
goto nospace;
n->m_next = o;
n = n->m_next;
n->m_len = m->m_len;
if (m->m_flags & M_EXT) {
n->m_data = m->m_data;
n->m_ext = m->m_ext;
n->m_flags |= M_EXT;
MEXT_ADD_REF(m);
n->m_ext.ref_cnt = m->m_ext.ref_cnt;
} else {
bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
}
m = m->m_next;
}
return top;
nospace:
m_freem(top);
mbstat.m_mcfail++; /* XXX: No consistency. */
return (NULL);
}
/*
* Copy data from an mbuf chain starting "off" bytes from the beginning,
* continuing for "len" bytes, into the indicated buffer.
*/
void
m_copydata(const struct mbuf *m, int off, int len, caddr_t cp)
{
u_int count;
KASSERT(off >= 0, ("m_copydata, negative off %d", off));
KASSERT(len >= 0, ("m_copydata, negative len %d", len));
while (off > 0) {
KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
if (off < m->m_len)
break;
off -= m->m_len;
m = m->m_next;
}
while (len > 0) {
KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
count = min(m->m_len - off, len);
bcopy(mtod(m, caddr_t) + off, cp, count);
len -= count;
cp += count;
off = 0;
m = m->m_next;
}
}
/*
* Copy a packet header mbuf chain into a completely new chain, including
* copying any mbuf clusters. Use this instead of m_copypacket() when
* you need a writable copy of an mbuf chain.
*/
struct mbuf *
m_dup(struct mbuf *m, int how)
{
struct mbuf **p, *top = NULL;
int remain, moff, nsize;
MBUF_CHECKSLEEP(how);
/* Sanity check */
if (m == NULL)
return (NULL);
M_ASSERTPKTHDR(m);
/* While there's more data, get a new mbuf, tack it on, and fill it */
remain = m->m_pkthdr.len;
moff = 0;
p = &top;
while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */
struct mbuf *n;
/* Get the next new mbuf */
if (remain >= MINCLSIZE) {
n = m_getcl(how, m->m_type, 0);
nsize = MCLBYTES;
} else {
n = m_get(how, m->m_type);
nsize = MLEN;
}
if (n == NULL)
goto nospace;
if (top == NULL) { /* First one, must be PKTHDR */
if (!m_dup_pkthdr(n, m, how)) {
m_free(n);
goto nospace;
}
nsize = MHLEN;
}
n->m_len = 0;
/* Link it into the new chain */
*p = n;
p = &n->m_next;
/* Copy data from original mbuf(s) into new mbuf */
while (n->m_len < nsize && m != NULL) {
int chunk = min(nsize - n->m_len, m->m_len - moff);
bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
moff += chunk;
n->m_len += chunk;
remain -= chunk;
if (moff == m->m_len) {
m = m->m_next;
moff = 0;
}
}
/* Check correct total mbuf length */
KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL),
("%s: bogus m_pkthdr.len", __func__));
}
return (top);
nospace:
m_freem(top);
mbstat.m_mcfail++; /* XXX: No consistency. */
return (NULL);
}
/*
* Concatenate mbuf chain n to m.
* Both chains must be of the same type (e.g. MT_DATA).
* Any m_pkthdr is not updated.
*/
void
m_cat(struct mbuf *m, struct mbuf *n)
{
while (m->m_next)
m = m->m_next;
while (n) {
if (m->m_flags & M_EXT ||
m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) {
/* just join the two chains */
m->m_next = n;
return;
}
/* splat the data from one into the other */
bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
(u_int)n->m_len);
m->m_len += n->m_len;
n = m_free(n);
}
}
void
m_adj(struct mbuf *mp, int req_len)
{
int len = req_len;
struct mbuf *m;
int count;
if ((m = mp) == NULL)
return;
if (len >= 0) {
/*
* Trim from head.
*/
while (m != NULL && len > 0) {
if (m->m_len <= len) {
len -= m->m_len;
m->m_len = 0;
m = m->m_next;
} else {
m->m_len -= len;
m->m_data += len;
len = 0;
}
}
m = mp;
if (mp->m_flags & M_PKTHDR)
m->m_pkthdr.len -= (req_len - len);
} else {
/*
* Trim from tail. Scan the mbuf chain,
* calculating its length and finding the last mbuf.
* If the adjustment only affects this mbuf, then just
* adjust and return. Otherwise, rescan and truncate
* after the remaining size.
*/
len = -len;
count = 0;
for (;;) {
count += m->m_len;
if (m->m_next == (struct mbuf *)0)
break;
m = m->m_next;
}
if (m->m_len >= len) {
m->m_len -= len;
if (mp->m_flags & M_PKTHDR)
mp->m_pkthdr.len -= len;
return;
}
count -= len;
if (count < 0)
count = 0;
/*
* Correct length for chain is "count".
* Find the mbuf with last data, adjust its length,
* and toss data from remaining mbufs on chain.
*/
m = mp;
if (m->m_flags & M_PKTHDR)
m->m_pkthdr.len = count;
for (; m; m = m->m_next) {
if (m->m_len >= count) {
m->m_len = count;
if (m->m_next != NULL) {
m_freem(m->m_next);
m->m_next = NULL;
}
break;
}
count -= m->m_len;
}
}
}
/*
* Rearange an mbuf chain so that len bytes are contiguous
* and in the data area of an mbuf (so that mtod and dtom
* will work for a structure of size len). Returns the resulting
* mbuf chain on success, frees it and returns null on failure.
* If there is room, it will add up to max_protohdr-len extra bytes to the
* contiguous region in an attempt to avoid being called next time.
*/
struct mbuf *
m_pullup(struct mbuf *n, int len)
{
struct mbuf *m;
int count;
int space;
/*
* If first mbuf has no cluster, and has room for len bytes
* without shifting current data, pullup into it,
* otherwise allocate a new mbuf to prepend to the chain.
*/
if ((n->m_flags & M_EXT) == 0 &&
n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
if (n->m_len >= len)
return (n);
m = n;
n = n->m_next;
len -= m->m_len;
} else {
if (len > MHLEN)
goto bad;
MGET(m, M_DONTWAIT, n->m_type);
if (m == NULL)
goto bad;
m->m_len = 0;
if (n->m_flags & M_PKTHDR)
M_MOVE_PKTHDR(m, n);
}
space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
do {
count = min(min(max(len, max_protohdr), space), n->m_len);
bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
(u_int)count);
len -= count;
m->m_len += count;
n->m_len -= count;
space -= count;
if (n->m_len)
n->m_data += count;
else
n = m_free(n);
} while (len > 0 && n);
if (len > 0) {
(void) m_free(m);
goto bad;
}
m->m_next = n;
return (m);
bad:
m_freem(n);
mbstat.m_mpfail++; /* XXX: No consistency. */
return (NULL);
}
/*
* Partition an mbuf chain in two pieces, returning the tail --
* all but the first len0 bytes. In case of failure, it returns NULL and
* attempts to restore the chain to its original state.
*
* Note that the resulting mbufs might be read-only, because the new
* mbuf can end up sharing an mbuf cluster with the original mbuf if
* the "breaking point" happens to lie within a cluster mbuf. Use the
* M_WRITABLE() macro to check for this case.
*/
struct mbuf *
m_split(struct mbuf *m0, int len0, int wait)
{
struct mbuf *m, *n;
u_int len = len0, remain;
MBUF_CHECKSLEEP(wait);
for (m = m0; m && len > m->m_len; m = m->m_next)
len -= m->m_len;
if (m == NULL)
return (NULL);
remain = m->m_len - len;
if (m0->m_flags & M_PKTHDR) {
MGETHDR(n, wait, m0->m_type);
if (n == NULL)
return (NULL);
n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
n->m_pkthdr.len = m0->m_pkthdr.len - len0;
m0->m_pkthdr.len = len0;
if (m->m_flags & M_EXT)
goto extpacket;
if (remain > MHLEN) {
/* m can't be the lead packet */
MH_ALIGN(n, 0);
n->m_next = m_split(m, len, wait);
if (n->m_next == NULL) {
(void) m_free(n);
return (NULL);
} else {
n->m_len = 0;
return (n);
}
} else
MH_ALIGN(n, remain);
} else if (remain == 0) {
n = m->m_next;
m->m_next = NULL;
return (n);
} else {
MGET(n, wait, m->m_type);
if (n == NULL)
return (NULL);
M_ALIGN(n, remain);
}
extpacket:
if (m->m_flags & M_EXT) {
n->m_flags |= M_EXT;
n->m_ext = m->m_ext;
MEXT_ADD_REF(m);
n->m_ext.ref_cnt = m->m_ext.ref_cnt;
n->m_data = m->m_data + len;
} else {
bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
}
n->m_len = remain;
m->m_len = len;
n->m_next = m->m_next;
m->m_next = NULL;
return (n);
}
/*
* Routine to copy from device local memory into mbufs.
* Note that `off' argument is offset into first mbuf of target chain from
* which to begin copying the data to.
*/
struct mbuf *
m_devget(char *buf, int totlen, int off, struct ifnet *ifp,
void (*copy)(char *from, caddr_t to, u_int len))
{
struct mbuf *m;
struct mbuf *top = NULL, **mp = &top;
int len;
if (off < 0 || off > MHLEN)
return (NULL);
while (totlen > 0) {
if (top == NULL) { /* First one, must be PKTHDR */
if (totlen + off >= MINCLSIZE) {
m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
len = MCLBYTES;
} else {
m = m_gethdr(M_DONTWAIT, MT_DATA);
len = MHLEN;
/* Place initial small packet/header at end of mbuf */
if (m && totlen + off + max_linkhdr <= MLEN) {
m->m_data += max_linkhdr;
len -= max_linkhdr;
}
}
if (m == NULL)
return NULL;
m->m_pkthdr.rcvif = ifp;
m->m_pkthdr.len = totlen;
} else {
if (totlen + off >= MINCLSIZE) {
m = m_getcl(M_DONTWAIT, MT_DATA, 0);
len = MCLBYTES;
} else {
m = m_get(M_DONTWAIT, MT_DATA);
len = MLEN;
}
if (m == NULL) {
m_freem(top);
return NULL;
}
}
if (off) {
m->m_data += off;
len -= off;
off = 0;
}
m->m_len = len = min(totlen, len);
if (copy)
copy(buf, mtod(m, caddr_t), (u_int)len);
else
bcopy(buf, mtod(m, caddr_t), (u_int)len);
buf += len;
*mp = m;
mp = &m->m_next;
totlen -= len;
}
return (top);
}
/*
* Copy data from a buffer back into the indicated mbuf chain,
* starting "off" bytes from the beginning, extending the mbuf
* chain if necessary.
*/
void
m_copyback(struct mbuf *m0, int off, int len, c_caddr_t cp)
{
int mlen;
struct mbuf *m = m0, *n;
int totlen = 0;
if (m0 == NULL)
return;
while (off > (mlen = m->m_len)) {
off -= mlen;
totlen += mlen;
if (m->m_next == NULL) {
n = m_get(M_DONTWAIT, m->m_type);
if (n == NULL)
goto out;
bzero(mtod(n, caddr_t), MLEN);
n->m_len = min(MLEN, len + off);
m->m_next = n;
}
m = m->m_next;
}
while (len > 0) {
mlen = min (m->m_len - off, len);
bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
cp += mlen;
len -= mlen;
mlen += off;
off = 0;
totlen += mlen;
if (len == 0)
break;
if (m->m_next == NULL) {
n = m_get(M_DONTWAIT, m->m_type);
if (n == NULL)
break;
n->m_len = min(MLEN, len);
m->m_next = n;
}
m = m->m_next;
}
out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
m->m_pkthdr.len = totlen;
}
/*
* Append the specified data to the indicated mbuf chain,
* Extend the mbuf chain if the new data does not fit in
* existing space.
*
* Return 1 if able to complete the job; otherwise 0.
*/
int
m_append(struct mbuf *m0, int len, c_caddr_t cp)
{
struct mbuf *m, *n;
int remainder, space;
for (m = m0; m->m_next != NULL; m = m->m_next)
;
remainder = len;
space = M_TRAILINGSPACE(m);
if (space > 0) {
/*
* Copy into available space.
*/
if (space > remainder)
space = remainder;
bcopy(cp, mtod(m, caddr_t) + m->m_len, space);
m->m_len += space;
cp += space, remainder -= space;
}
while (remainder > 0) {
/*
* Allocate a new mbuf; could check space
* and allocate a cluster instead.
*/
n = m_get(M_DONTWAIT, m->m_type);
if (n == NULL)
break;
n->m_len = min(MLEN, remainder);
bcopy(cp, mtod(n, caddr_t), n->m_len);
cp += n->m_len, remainder -= n->m_len;
m->m_next = n;
m = n;
}
if (m0->m_flags & M_PKTHDR)
m0->m_pkthdr.len += len - remainder;
return (remainder == 0);
}
/*
* Apply function f to the data in an mbuf chain starting "off" bytes from
* the beginning, continuing for "len" bytes.
*/
int
m_apply(struct mbuf *m, int off, int len,
int (*f)(void *, void *, u_int), void *arg)
{
u_int count;
int rval;
KASSERT(off >= 0, ("m_apply, negative off %d", off));
KASSERT(len >= 0, ("m_apply, negative len %d", len));
while (off > 0) {
KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
if (off < m->m_len)
break;
off -= m->m_len;
m = m->m_next;
}
while (len > 0) {
KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
count = min(m->m_len - off, len);
rval = (*f)(arg, mtod(m, caddr_t) + off, count);
if (rval)
return (rval);
len -= count;
off = 0;
m = m->m_next;
}
return (0);
}
/*
* Return a pointer to mbuf/offset of location in mbuf chain.
*/
struct mbuf *
m_getptr(struct mbuf *m, int loc, int *off)
{
while (loc >= 0) {
/* Normal end of search. */
if (m->m_len > loc) {
*off = loc;
return (m);
} else {
loc -= m->m_len;
if (m->m_next == NULL) {
if (loc == 0) {
/* Point at the end of valid data. */
*off = m->m_len;
return (m);
}
return (NULL);
}
m = m->m_next;
}
}
return (NULL);
}
void
m_print(const struct mbuf *m, int maxlen)
{
int len;
int pdata;
const struct mbuf *m2;
if (m->m_flags & M_PKTHDR)
len = m->m_pkthdr.len;
else
len = -1;
m2 = m;
while (m2 != NULL && (len == -1 || len)) {
pdata = m2->m_len;
if (maxlen != -1 && pdata > maxlen)
pdata = maxlen;
printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len,
m2->m_next, m2->m_flags, "\20\20freelist\17skipfw"
"\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly"
"\3eor\2pkthdr\1ext", pdata ? "" : "\n");
if (pdata)
printf(", %*D\n", m2->m_len, (u_char *)m2->m_data, "-");
if (len != -1)
len -= m2->m_len;
m2 = m2->m_next;
}
if (len > 0)
printf("%d bytes unaccounted for.\n", len);
return;
}
u_int
m_fixhdr(struct mbuf *m0)
{
u_int len;
len = m_length(m0, NULL);
m0->m_pkthdr.len = len;
return (len);
}
u_int
m_length(struct mbuf *m0, struct mbuf **last)
{
struct mbuf *m;
u_int len;
len = 0;
for (m = m0; m != NULL; m = m->m_next) {
len += m->m_len;
if (m->m_next == NULL)
break;
}
if (last != NULL)
*last = m;
return (len);
}
/*
* Defragment a mbuf chain, returning the shortest possible
* chain of mbufs and clusters. If allocation fails and
* this cannot be completed, NULL will be returned, but
* the passed in chain will be unchanged. Upon success,
* the original chain will be freed, and the new chain
* will be returned.
*
* If a non-packet header is passed in, the original
* mbuf (chain?) will be returned unharmed.
*/
struct mbuf *
m_defrag(struct mbuf *m0, int how)
{
struct mbuf *m_new = NULL, *m_final = NULL;
int progress = 0, length;
MBUF_CHECKSLEEP(how);
if (!(m0->m_flags & M_PKTHDR))
return (m0);
m_fixhdr(m0); /* Needed sanity check */
#ifdef MBUF_STRESS_TEST
if (m_defragrandomfailures) {
int temp = arc4random() & 0xff;
if (temp == 0xba)
goto nospace;
}
#endif
if (m0->m_pkthdr.len > MHLEN)
m_final = m_getcl(how, MT_DATA, M_PKTHDR);
else
m_final = m_gethdr(how, MT_DATA);
if (m_final == NULL)
goto nospace;
if (m_dup_pkthdr(m_final, m0, how) == 0)
goto nospace;
m_new = m_final;
while (progress < m0->m_pkthdr.len) {
length = m0->m_pkthdr.len - progress;
if (length > MCLBYTES)
length = MCLBYTES;
if (m_new == NULL) {
if (length > MLEN)
m_new = m_getcl(how, MT_DATA, 0);
else
m_new = m_get(how, MT_DATA);
if (m_new == NULL)
goto nospace;
}
m_copydata(m0, progress, length, mtod(m_new, caddr_t));
progress += length;
m_new->m_len = length;
if (m_new != m_final)
m_cat(m_final, m_new);
m_new = NULL;
}
#ifdef MBUF_STRESS_TEST
if (m0->m_next == NULL)
m_defraguseless++;
#endif
m_freem(m0);
m0 = m_final;
#ifdef MBUF_STRESS_TEST
m_defragpackets++;
m_defragbytes += m0->m_pkthdr.len;
#endif
return (m0);
nospace:
#ifdef MBUF_STRESS_TEST
m_defragfailure++;
#endif
if (m_final)
m_freem(m_final);
return (NULL);
}
#ifdef MBUF_STRESS_TEST
/*
* Fragment an mbuf chain. There's no reason you'd ever want to do
* this in normal usage, but it's great for stress testing various
* mbuf consumers.
*
* If fragmentation is not possible, the original chain will be
* returned.
*
* Possible length values:
* 0 no fragmentation will occur
* > 0 each fragment will be of the specified length
* -1 each fragment will be the same random value in length
* -2 each fragment's length will be entirely random
* (Random values range from 1 to 256)
*/
struct mbuf *
m_fragment(struct mbuf *m0, int how, int length)
{
struct mbuf *m_new = NULL, *m_final = NULL;
int progress = 0;
if (!(m0->m_flags & M_PKTHDR))
return (m0);
if ((length == 0) || (length < -2))
return (m0);
m_fixhdr(m0); /* Needed sanity check */
m_final = m_getcl(how, MT_DATA, M_PKTHDR);
if (m_final == NULL)
goto nospace;
if (m_dup_pkthdr(m_final, m0, how) == 0)
goto nospace;
m_new = m_final;
if (length == -1)
length = 1 + (arc4random() & 255);
while (progress < m0->m_pkthdr.len) {
int fraglen;
if (length > 0)
fraglen = length;
else
fraglen = 1 + (arc4random() & 255);
if (fraglen > m0->m_pkthdr.len - progress)
fraglen = m0->m_pkthdr.len - progress;
if (fraglen > MCLBYTES)
fraglen = MCLBYTES;
if (m_new == NULL) {
m_new = m_getcl(how, MT_DATA, 0);
if (m_new == NULL)
goto nospace;
}
m_copydata(m0, progress, fraglen, mtod(m_new, caddr_t));
progress += fraglen;
m_new->m_len = fraglen;
if (m_new != m_final)
m_cat(m_final, m_new);
m_new = NULL;
}
m_freem(m0);
m0 = m_final;
return (m0);
nospace:
if (m_final)
m_freem(m_final);
/* Return the original chain on failure */
return (m0);
}
#endif
struct mbuf *
m_uiotombuf(struct uio *uio, int how, int len)
{
struct mbuf *m_new = NULL, *m_final = NULL;
int progress = 0, error = 0, length, total;
if (len > 0)
total = min(uio->uio_resid, len);
else
total = uio->uio_resid;
if (total > MHLEN)
m_final = m_getcl(how, MT_DATA, M_PKTHDR);
else
m_final = m_gethdr(how, MT_DATA);
if (m_final == NULL)
goto nospace;
m_new = m_final;
while (progress < total) {
length = total - progress;
if (length > MCLBYTES)
length = MCLBYTES;
if (m_new == NULL) {
if (length > MLEN)
m_new = m_getcl(how, MT_DATA, 0);
else
m_new = m_get(how, MT_DATA);
if (m_new == NULL)
goto nospace;
}
error = uiomove(mtod(m_new, void *), length, uio);
if (error)
goto nospace;
progress += length;
m_new->m_len = length;
if (m_new != m_final)
m_cat(m_final, m_new);
m_new = NULL;
}
m_fixhdr(m_final);
return (m_final);
nospace:
if (m_new)
m_free(m_new);
if (m_final)
m_freem(m_final);
return (NULL);
}
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