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freebsd-src/sys/net80211/ieee80211_output.c
Sam Leffler 0a915fad5d MFp4 changes to fix locking issues and correct reference 
count handling of station entries in hostap mode:

Input path:

o driver is now expected to find the node associated with the
  sender of a received frame; use ic_bss if none is located
o driver passes the (referenced) node into ieee80211_input for
  use within the wlan module and is responsible for cleaning up
  on return
o the antenna state is no longer passed up with each frame; this
  is now considered driver-private state and drivers are responsible
  for keeping it in the driver-private part of a node

Output path:

Revamp output path for management frames to eliminate redundant
locking that causes problems and to correct reference counting
bogosity that occurs when stations are timed out due to inactivity
(in AP mode).  On output the refcnt'd node is stashed in the pkthdr's
recvif field (yech) and retrieved by the driver.  This eliminates
an unref/ref scenario and related node table unlock/lock due to the
driver looking up the node.  This is particularly important when
stations are timed out as this causes a lock order reversal that
can result in a deadlock.  As a byproduct we also reduce the overhead
for sending management frames (minimal).  Additional fallout from
this is a change to ieee80211_encap to return a refcn't node for
tieing to the outbound frame.  Node refcnts are not reclaimed until
after a frame is completely processed (e.g. in the tx interrupt
handler).  This is especially important for timed out stations as
this deref will be the final one causing the node entry to be
reclaimed.

Additional semi-related changes:
o replace m_copym use with m_copypacket (optimization)
o add assert to verify ic_bss is never free'd during normal operation
o add comments explaining calling conventions by drivers for frames
  going in each direction
o remove extraneous code that "cannot be executed" (e.g. because
  pointers may never be null)
2003-08-19 22:17:04 +00:00

552 lines
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/*-
* Copyright (c) 2001 Atsushi Onoe
* 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL") version 2 as published by the Free
* Software Foundation.
*
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/endian.h>
#include <sys/errno.h>
#include <sys/bus.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <machine/atomic.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_media.h>
#include <net/if_arp.h>
#include <net/ethernet.h>
#include <net/if_llc.h>
#include <net80211/ieee80211_var.h>
#include <net/bpf.h>
#ifdef INET
#include <netinet/in.h>
#include <netinet/if_ether.h>
#endif
/*
* Send a management frame to the specified node. The node pointer
* must have a reference as the pointer will be passed to the driver
* and potentially held for a long time. If the frame is successfully
* dispatched to the driver, then it is responsible for freeing the
* reference (and potentially free'ing up any associated storage).
*/
static int
ieee80211_mgmt_output(struct ifnet *ifp, struct ieee80211_node *ni,
struct mbuf *m, int type)
{
struct ieee80211com *ic = (void *)ifp;
struct ieee80211_frame *wh;
KASSERT(ni != NULL, ("null node"));
ni->ni_inact = 0;
/*
* Yech, hack alert! We want to pass the node down to the
* driver's start routine. If we don't do so then the start
* routine must immediately look it up again and that can
* cause a lock order reversal if, for example, this frame
* is being sent because the station is being timedout and
* the frame being sent is a DEAUTH message. We could stick
* this in an m_tag and tack that on to the mbuf. However
* that's rather expensive to do for every frame so instead
* we stuff it in the rcvif field since outbound frames do
* not (presently) use this.
*/
M_PREPEND(m, sizeof(struct ieee80211_frame), M_DONTWAIT);
if (m == NULL)
return ENOMEM;
KASSERT(m->m_pkthdr.rcvif == NULL, ("rcvif not null"));
m->m_pkthdr.rcvif = (void *)ni;
wh = mtod(m, struct ieee80211_frame *);
wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_MGT | type;
wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
*(u_int16_t *)wh->i_dur = 0;
*(u_int16_t *)wh->i_seq =
htole16(ni->ni_txseq << IEEE80211_SEQ_SEQ_SHIFT);
ni->ni_txseq++;
IEEE80211_ADDR_COPY(wh->i_addr1, ni->ni_macaddr);
IEEE80211_ADDR_COPY(wh->i_addr2, ic->ic_myaddr);
IEEE80211_ADDR_COPY(wh->i_addr3, ni->ni_bssid);
if (ifp->if_flags & IFF_DEBUG) {
/* avoid to print too many frames */
if (ic->ic_opmode == IEEE80211_M_IBSS ||
#ifdef IEEE80211_DEBUG
ieee80211_debug > 1 ||
#endif
(type & IEEE80211_FC0_SUBTYPE_MASK) !=
IEEE80211_FC0_SUBTYPE_PROBE_RESP)
if_printf(ifp, "sending %s to %s on channel %u\n",
ieee80211_mgt_subtype_name[
(type & IEEE80211_FC0_SUBTYPE_MASK)
>> IEEE80211_FC0_SUBTYPE_SHIFT],
ether_sprintf(ni->ni_macaddr),
ieee80211_chan2ieee(ic, ni->ni_chan));
}
IF_ENQUEUE(&ic->ic_mgtq, m);
ifp->if_timer = 1;
(*ifp->if_start)(ifp);
return 0;
}
/*
* Encapsulate an outbound data frame. The mbuf chain is updated and
* a reference to the destination node is returned. If an error is
* encountered NULL is returned and the node reference will also be NULL.
*
* NB: The caller is responsible for free'ing a returned node reference.
* The convention is ic_bss is not reference counted; the caller must
* maintain that.
*/
struct mbuf *
ieee80211_encap(struct ifnet *ifp, struct mbuf *m, struct ieee80211_node **pni)
{
struct ieee80211com *ic = (void *)ifp;
struct ether_header eh;
struct ieee80211_frame *wh;
struct ieee80211_node *ni = NULL;
struct llc *llc;
if (m->m_len < sizeof(struct ether_header)) {
m = m_pullup(m, sizeof(struct ether_header));
if (m == NULL) {
/* XXX statistic */
goto bad;
}
}
memcpy(&eh, mtod(m, caddr_t), sizeof(struct ether_header));
if (ic->ic_opmode != IEEE80211_M_STA) {
ni = ieee80211_find_node(ic, eh.ether_dhost);
if (ni == NULL) {
/*
* When not in station mode the
* destination address should always be
* in the node table unless this is a
* multicast/broadcast frame.
*/
if (!IEEE80211_IS_MULTICAST(eh.ether_dhost)) {
/* ic->ic_stats.st_tx_nonode++; XXX statistic */
goto bad;
}
ni = ic->ic_bss;
}
} else
ni = ic->ic_bss;
ni->ni_inact = 0;
m_adj(m, sizeof(struct ether_header) - sizeof(struct llc));
llc = mtod(m, struct llc *);
llc->llc_dsap = llc->llc_ssap = LLC_SNAP_LSAP;
llc->llc_control = LLC_UI;
llc->llc_snap.org_code[0] = 0;
llc->llc_snap.org_code[1] = 0;
llc->llc_snap.org_code[2] = 0;
llc->llc_snap.ether_type = eh.ether_type;
M_PREPEND(m, sizeof(struct ieee80211_frame), M_DONTWAIT);
if (m == NULL)
goto bad;
wh = mtod(m, struct ieee80211_frame *);
wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_DATA;
*(u_int16_t *)wh->i_dur = 0;
*(u_int16_t *)wh->i_seq =
htole16(ni->ni_txseq << IEEE80211_SEQ_SEQ_SHIFT);
ni->ni_txseq++;
switch (ic->ic_opmode) {
case IEEE80211_M_STA:
wh->i_fc[1] = IEEE80211_FC1_DIR_TODS;
IEEE80211_ADDR_COPY(wh->i_addr1, ni->ni_bssid);
IEEE80211_ADDR_COPY(wh->i_addr2, eh.ether_shost);
IEEE80211_ADDR_COPY(wh->i_addr3, eh.ether_dhost);
break;
case IEEE80211_M_IBSS:
case IEEE80211_M_AHDEMO:
wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
IEEE80211_ADDR_COPY(wh->i_addr1, eh.ether_dhost);
IEEE80211_ADDR_COPY(wh->i_addr2, eh.ether_shost);
IEEE80211_ADDR_COPY(wh->i_addr3, ni->ni_bssid);
break;
case IEEE80211_M_HOSTAP:
wh->i_fc[1] = IEEE80211_FC1_DIR_FROMDS;
IEEE80211_ADDR_COPY(wh->i_addr1, eh.ether_dhost);
IEEE80211_ADDR_COPY(wh->i_addr2, ni->ni_bssid);
IEEE80211_ADDR_COPY(wh->i_addr3, eh.ether_shost);
break;
case IEEE80211_M_MONITOR:
goto bad;
}
*pni = ni;
return m;
bad:
if (m != NULL)
m_freem(m);
if (ni && ni != ic->ic_bss)
ieee80211_free_node(ic, ni);
*pni = NULL;
return NULL;
}
/*
* Add a supported rates element id to a frame.
*/
u_int8_t *
ieee80211_add_rates(u_int8_t *frm, const struct ieee80211_rateset *rs)
{
int nrates;
*frm++ = IEEE80211_ELEMID_RATES;
nrates = rs->rs_nrates;
if (nrates > IEEE80211_RATE_SIZE)
nrates = IEEE80211_RATE_SIZE;
*frm++ = nrates;
memcpy(frm, rs->rs_rates, nrates);
return frm + nrates;
}
/*
* Add an extended supported rates element id to a frame.
*/
u_int8_t *
ieee80211_add_xrates(u_int8_t *frm, const struct ieee80211_rateset *rs)
{
/*
* Add an extended supported rates element if operating in 11g mode.
*/
if (rs->rs_nrates > IEEE80211_RATE_SIZE) {
int nrates = rs->rs_nrates - IEEE80211_RATE_SIZE;
*frm++ = IEEE80211_ELEMID_XRATES;
*frm++ = nrates;
memcpy(frm, rs->rs_rates + IEEE80211_RATE_SIZE, nrates);
frm += nrates;
}
return frm;
}
/*
* Add an ssid elemet to a frame.
*/
static u_int8_t *
ieee80211_add_ssid(u_int8_t *frm, const u_int8_t *ssid, u_int len)
{
*frm++ = IEEE80211_ELEMID_SSID;
*frm++ = len;
memcpy(frm, ssid, len);
return frm + len;
}
static struct mbuf *
ieee80211_getmbuf(int flags, int type, u_int pktlen)
{
struct mbuf *m;
if (pktlen > MHLEN)
MGETHDR(m, flags, type);
else
m = m_getcl(flags, type, M_PKTHDR);
return m;
}
/*
* Send a management frame. The node is for the destination (or ic_bss
* when in station mode). Nodes other than ic_bss have their reference
* count bumped to reflect our use for an indeterminant time.
*/
int
ieee80211_send_mgmt(struct ieee80211com *ic, struct ieee80211_node *ni,
int type, int arg)
{
#define senderr(_x) do { ret = _x; goto bad; } while (0)
struct ifnet *ifp = &ic->ic_if;
struct mbuf *m;
u_int8_t *frm;
enum ieee80211_phymode mode;
u_int16_t capinfo;
int ret, timer;
KASSERT(ni != NULL, ("null node"));
/*
* Hold a reference on the node so it doesn't go away until after
* the xmit is complete all the way in the driver. On error we
* will remove our reference.
*/
if (ni != ic->ic_bss)
ieee80211_ref_node(ni);
timer = 0;
switch (type) {
case IEEE80211_FC0_SUBTYPE_PROBE_REQ:
/*
* prreq frame format
* [tlv] ssid
* [tlv] supported rates
* [tlv] extended supported rates
*/
m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
2 + ic->ic_des_esslen
+ 2 + IEEE80211_RATE_SIZE
+ 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
if (m == NULL)
senderr(ENOMEM);
m->m_data += sizeof(struct ieee80211_frame);
frm = mtod(m, u_int8_t *);
frm = ieee80211_add_ssid(frm, ic->ic_des_essid, ic->ic_des_esslen);
mode = ieee80211_chan2mode(ic, ni->ni_chan);
frm = ieee80211_add_rates(frm, &ic->ic_sup_rates[mode]);
frm = ieee80211_add_xrates(frm, &ic->ic_sup_rates[mode]);
m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
timer = IEEE80211_TRANS_WAIT;
break;
case IEEE80211_FC0_SUBTYPE_PROBE_RESP:
/*
* probe response frame format
* [8] time stamp
* [2] beacon interval
* [2] cabability information
* [tlv] ssid
* [tlv] supported rates
* [tlv] parameter set (IBSS)
* [tlv] extended supported rates
*/
m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
8 + 2 + 2 + 2
+ 2 + ni->ni_esslen
+ 2 + IEEE80211_RATE_SIZE
+ 6
+ 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
if (m == NULL)
senderr(ENOMEM);
m->m_data += sizeof(struct ieee80211_frame);
frm = mtod(m, u_int8_t *);
memset(frm, 0, 8); /* timestamp should be filled later */
frm += 8;
*(u_int16_t *)frm = htole16(ic->ic_bss->ni_intval);
frm += 2;
if (ic->ic_opmode == IEEE80211_M_IBSS)
capinfo = IEEE80211_CAPINFO_IBSS;
else
capinfo = IEEE80211_CAPINFO_ESS;
if (ic->ic_flags & IEEE80211_F_WEPON)
capinfo |= IEEE80211_CAPINFO_PRIVACY;
*(u_int16_t *)frm = htole16(capinfo);
frm += 2;
frm = ieee80211_add_ssid(frm, ic->ic_bss->ni_essid,
ic->ic_bss->ni_esslen);
frm = ieee80211_add_rates(frm, &ic->ic_bss->ni_rates);
if (ic->ic_opmode == IEEE80211_M_IBSS) {
*frm++ = IEEE80211_ELEMID_IBSSPARMS;
*frm++ = 2;
*frm++ = 0; *frm++ = 0; /* TODO: ATIM window */
} else { /* IEEE80211_M_HOSTAP */
/* TODO: TIM */
*frm++ = IEEE80211_ELEMID_TIM;
*frm++ = 4; /* length */
*frm++ = 0; /* DTIM count */
*frm++ = 1; /* DTIM period */
*frm++ = 0; /* bitmap control */
*frm++ = 0; /* Partial Virtual Bitmap (variable length) */
}
frm = ieee80211_add_xrates(frm, &ic->ic_bss->ni_rates);
m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
break;
case IEEE80211_FC0_SUBTYPE_AUTH:
MGETHDR(m, M_DONTWAIT, MT_DATA);
if (m == NULL)
senderr(ENOMEM);
MH_ALIGN(m, 2 * 3);
m->m_pkthdr.len = m->m_len = 6;
frm = mtod(m, u_int8_t *);
/* TODO: shared key auth */
((u_int16_t *)frm)[0] = htole16(IEEE80211_AUTH_ALG_OPEN);
((u_int16_t *)frm)[1] = htole16(arg); /* sequence number */
((u_int16_t *)frm)[2] = 0; /* status */
if (ic->ic_opmode == IEEE80211_M_STA)
timer = IEEE80211_TRANS_WAIT;
break;
case IEEE80211_FC0_SUBTYPE_DEAUTH:
if (ifp->if_flags & IFF_DEBUG)
if_printf(ifp, "station %s deauthenticate (reason %d)\n",
ether_sprintf(ni->ni_macaddr), arg);
MGETHDR(m, M_DONTWAIT, MT_DATA);
if (m == NULL)
senderr(ENOMEM);
MH_ALIGN(m, 2);
m->m_pkthdr.len = m->m_len = 2;
*mtod(m, u_int16_t *) = htole16(arg); /* reason */
break;
case IEEE80211_FC0_SUBTYPE_ASSOC_REQ:
case IEEE80211_FC0_SUBTYPE_REASSOC_REQ:
/*
* asreq frame format
* [2] capability information
* [2] listen interval
* [6*] current AP address (reassoc only)
* [tlv] ssid
* [tlv] supported rates
* [tlv] extended supported rates
*/
m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
sizeof(capinfo)
+ sizeof(u_int16_t)
+ IEEE80211_ADDR_LEN
+ 2 + ni->ni_esslen
+ 2 + IEEE80211_RATE_SIZE
+ 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
if (m == NULL)
senderr(ENOMEM);
m->m_data += sizeof(struct ieee80211_frame);
frm = mtod(m, u_int8_t *);
capinfo = 0;
if (ic->ic_opmode == IEEE80211_M_IBSS)
capinfo |= IEEE80211_CAPINFO_IBSS;
else /* IEEE80211_M_STA */
capinfo |= IEEE80211_CAPINFO_ESS;
if (ic->ic_flags & IEEE80211_F_WEPON)
capinfo |= IEEE80211_CAPINFO_PRIVACY;
if (ic->ic_flags & IEEE80211_F_SHPREAMBLE)
capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
if (ic->ic_flags & IEEE80211_F_SHSLOT)
capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
*(u_int16_t *)frm = htole16(capinfo);
frm += 2;
*(u_int16_t *)frm = htole16(ic->ic_lintval);
frm += 2;
if (type == IEEE80211_FC0_SUBTYPE_REASSOC_REQ) {
IEEE80211_ADDR_COPY(frm, ic->ic_bss->ni_bssid);
frm += IEEE80211_ADDR_LEN;
}
frm = ieee80211_add_ssid(frm, ni->ni_essid, ni->ni_esslen);
frm = ieee80211_add_rates(frm, &ni->ni_rates);
frm = ieee80211_add_xrates(frm, &ni->ni_rates);
m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
timer = IEEE80211_TRANS_WAIT;
break;
case IEEE80211_FC0_SUBTYPE_ASSOC_RESP:
case IEEE80211_FC0_SUBTYPE_REASSOC_RESP:
/*
* asreq frame format
* [2] capability information
* [2] status
* [2] association ID
* [tlv] supported rates
* [tlv] extended supported rates
*/
m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
sizeof(capinfo)
+ sizeof(u_int16_t)
+ sizeof(u_int16_t)
+ 2 + IEEE80211_RATE_SIZE
+ 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
if (m == NULL)
senderr(ENOMEM);
m->m_data += sizeof(struct ieee80211_frame);
frm = mtod(m, u_int8_t *);
capinfo = IEEE80211_CAPINFO_ESS;
if (ic->ic_flags & IEEE80211_F_WEPON)
capinfo |= IEEE80211_CAPINFO_PRIVACY;
*(u_int16_t *)frm = htole16(capinfo);
frm += 2;
*(u_int16_t *)frm = htole16(arg); /* status */
frm += 2;
if (arg == IEEE80211_STATUS_SUCCESS)
*(u_int16_t *)frm = htole16(ni->ni_associd);
frm += 2;
frm = ieee80211_add_rates(frm, &ni->ni_rates);
frm = ieee80211_add_xrates(frm, &ni->ni_rates);
m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
break;
case IEEE80211_FC0_SUBTYPE_DISASSOC:
if (ifp->if_flags & IFF_DEBUG)
if_printf(ifp, "station %s disassociate (reason %d)\n",
ether_sprintf(ni->ni_macaddr), arg);
MGETHDR(m, M_DONTWAIT, MT_DATA);
if (m == NULL)
senderr(ENOMEM);
MH_ALIGN(m, 2);
m->m_pkthdr.len = m->m_len = 2;
*mtod(m, u_int16_t *) = htole16(arg); /* reason */
break;
default:
IEEE80211_DPRINTF(("%s: invalid mgmt frame type %u\n",
__func__, type));
senderr(EINVAL);
/* NOTREACHED */
}
ret = ieee80211_mgmt_output(ifp, ni, m, type);
if (ret == 0) {
if (timer)
ic->ic_mgt_timer = timer;
} else {
bad:
if (ni != ic->ic_bss) /* remove ref we added */
ieee80211_free_node(ic, ni);
}
return ret;
#undef senderr
}
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