ieee80211_rx.c

linux 内核源代码

/*
 * Original code based Host AP (software wireless LAN access point) driver
 * for Intersil Prism2/2.5/3 - hostap.o module, common routines
 *
 * Copyright (c) 2001-2002, SSH Communications Security Corp and Jouni Malinen
 * <[e-mail]>
 * Copyright (c) 2002-2003, Jouni Malinen <[e-mail]>
 * Copyright (c) 2004-2005, Intel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation. See README and COPYING for
 * more details.
 */

#include <linux/compiler.h>
#include <linux/errno.h>
#include <linux/if_arp.h>
#include <linux/in6.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/proc_fs.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/tcp.h>
#include <linux/types.h>
#include <linux/wireless.h>
#include <linux/etherdevice.h>
#include <asm/uaccess.h>
#include <linux/ctype.h>

#include <net/ieee80211.h>

static void ieee80211_monitor_rx(struct ieee80211_device *ieee,
					struct sk_buff *skb,
					struct ieee80211_rx_stats *rx_stats)
{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
	u16 fc = le16_to_cpu(hdr->frame_ctl);

	skb->dev = ieee->dev;
	skb_reset_mac_header(skb);
	skb_pull(skb, ieee80211_get_hdrlen(fc));
	skb->pkt_type = PACKET_OTHERHOST;
	skb->protocol = __constant_htons(ETH_P_80211_RAW);
	memset(skb->cb, 0, sizeof(skb->cb));
	netif_rx(skb);
}

/* Called only as a tasklet (software IRQ) */
static struct ieee80211_frag_entry *ieee80211_frag_cache_find(struct
							      ieee80211_device
							      *ieee,
							      unsigned int seq,
							      unsigned int frag,
							      u8 * src,
							      u8 * dst)
{
	struct ieee80211_frag_entry *entry;
	int i;

	for (i = 0; i < IEEE80211_FRAG_CACHE_LEN; i++) {
		entry = &ieee->frag_cache[i];
		if (entry->skb != NULL &&
		    time_after(jiffies, entry->first_frag_time + 2 * HZ)) {
			IEEE80211_DEBUG_FRAG("expiring fragment cache entry "
					     "seq=%u last_frag=%u\n",
					     entry->seq, entry->last_frag);
			dev_kfree_skb_any(entry->skb);
			entry->skb = NULL;
		}

		if (entry->skb != NULL && entry->seq == seq &&
		    (entry->last_frag + 1 == frag || frag == -1) &&
		    !compare_ether_addr(entry->src_addr, src) &&
		    !compare_ether_addr(entry->dst_addr, dst))
			return entry;
	}

	return NULL;
}

/* Called only as a tasklet (software IRQ) */
static struct sk_buff *ieee80211_frag_cache_get(struct ieee80211_device *ieee,
						struct ieee80211_hdr_4addr *hdr)
{
	struct sk_buff *skb = NULL;
	u16 sc;
	unsigned int frag, seq;
	struct ieee80211_frag_entry *entry;

	sc = le16_to_cpu(hdr->seq_ctl);
	frag = WLAN_GET_SEQ_FRAG(sc);
	seq = WLAN_GET_SEQ_SEQ(sc);

	if (frag == 0) {
		/* Reserve enough space to fit maximum frame length */
		skb = dev_alloc_skb(ieee->dev->mtu +
				    sizeof(struct ieee80211_hdr_4addr) +
				    8 /* LLC */  +
				    2 /* alignment */  +
				    8 /* WEP */  + ETH_ALEN /* WDS */ );
		if (skb == NULL)
			return NULL;

		entry = &ieee->frag_cache[ieee->frag_next_idx];
		ieee->frag_next_idx++;
		if (ieee->frag_next_idx >= IEEE80211_FRAG_CACHE_LEN)
			ieee->frag_next_idx = 0;

		if (entry->skb != NULL)
			dev_kfree_skb_any(entry->skb);

		entry->first_frag_time = jiffies;
		entry->seq = seq;
		entry->last_frag = frag;
		entry->skb = skb;
		memcpy(entry->src_addr, hdr->addr2, ETH_ALEN);
		memcpy(entry->dst_addr, hdr->addr1, ETH_ALEN);
	} else {
		/* received a fragment of a frame for which the head fragment
		 * should have already been received */
		entry = ieee80211_frag_cache_find(ieee, seq, frag, hdr->addr2,
						  hdr->addr1);
		if (entry != NULL) {
			entry->last_frag = frag;
			skb = entry->skb;
		}
	}

	return skb;
}

/* Called only as a tasklet (software IRQ) */
static int ieee80211_frag_cache_invalidate(struct ieee80211_device *ieee,
					   struct ieee80211_hdr_4addr *hdr)
{
	u16 sc;
	unsigned int seq;
	struct ieee80211_frag_entry *entry;

	sc = le16_to_cpu(hdr->seq_ctl);
	seq = WLAN_GET_SEQ_SEQ(sc);

	entry = ieee80211_frag_cache_find(ieee, seq, -1, hdr->addr2,
					  hdr->addr1);

	if (entry == NULL) {
		IEEE80211_DEBUG_FRAG("could not invalidate fragment cache "
				     "entry (seq=%u)\n", seq);
		return -1;
	}

	entry->skb = NULL;
	return 0;
}

#ifdef NOT_YET
/* ieee80211_rx_frame_mgtmt
 *
 * Responsible for handling management control frames
 *
 * Called by ieee80211_rx */
static int
ieee80211_rx_frame_mgmt(struct ieee80211_device *ieee, struct sk_buff *skb,
			struct ieee80211_rx_stats *rx_stats, u16 type,
			u16 stype)
{
	if (ieee->iw_mode == IW_MODE_MASTER) {
		printk(KERN_DEBUG "%s: Master mode not yet suppported.\n",
		       ieee->dev->name);
		return 0;
/*
  hostap_update_sta_ps(ieee, (struct hostap_ieee80211_hdr_4addr *)
  skb->data);*/
	}

	if (ieee->hostapd && type == WLAN_FC_TYPE_MGMT) {
		if (stype == WLAN_FC_STYPE_BEACON &&
		    ieee->iw_mode == IW_MODE_MASTER) {
			struct sk_buff *skb2;
			/* Process beacon frames also in kernel driver to
			 * update STA(AP) table statistics */
			skb2 = skb_clone(skb, GFP_ATOMIC);
			if (skb2)
				hostap_rx(skb2->dev, skb2, rx_stats);
		}

		/* send management frames to the user space daemon for
		 * processing */
		ieee->apdevstats.rx_packets++;
		ieee->apdevstats.rx_bytes += skb->len;
		prism2_rx_80211(ieee->apdev, skb, rx_stats, PRISM2_RX_MGMT);
		return 0;
	}

	if (ieee->iw_mode == IW_MODE_MASTER) {
		if (type != WLAN_FC_TYPE_MGMT && type != WLAN_FC_TYPE_CTRL) {
			printk(KERN_DEBUG "%s: unknown management frame "
			       "(type=0x%02x, stype=0x%02x) dropped\n",
			       skb->dev->name, type, stype);
			return -1;
		}

		hostap_rx(skb->dev, skb, rx_stats);
		return 0;
	}

	printk(KERN_DEBUG "%s: hostap_rx_frame_mgmt: management frame "
	       "received in non-Host AP mode\n", skb->dev->name);
	return -1;
}
#endif

/* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
/* Ethernet-II snap header (RFC1042 for most EtherTypes) */
static unsigned char rfc1042_header[] = { 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };

/* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
static unsigned char bridge_tunnel_header[] =
    { 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
/* No encapsulation header if EtherType < 0x600 (=length) */

/* Called by ieee80211_rx_frame_decrypt */
static int ieee80211_is_eapol_frame(struct ieee80211_device *ieee,
				    struct sk_buff *skb)
{
	struct net_device *dev = ieee->dev;
	u16 fc, ethertype;
	struct ieee80211_hdr_3addr *hdr;
	u8 *pos;

	if (skb->len < 24)
		return 0;

	hdr = (struct ieee80211_hdr_3addr *)skb->data;
	fc = le16_to_cpu(hdr->frame_ctl);

	/* check that the frame is unicast frame to us */
	if ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
	    IEEE80211_FCTL_TODS &&
	    !compare_ether_addr(hdr->addr1, dev->dev_addr) &&
	    !compare_ether_addr(hdr->addr3, dev->dev_addr)) {
		/* ToDS frame with own addr BSSID and DA */
	} else if ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
		   IEEE80211_FCTL_FROMDS &&
		   !compare_ether_addr(hdr->addr1, dev->dev_addr)) {
		/* FromDS frame with own addr as DA */
	} else
		return 0;

	if (skb->len < 24 + 8)
		return 0;

	/* check for port access entity Ethernet type */
	pos = skb->data + 24;
	ethertype = (pos[6] << 8) | pos[7];
	if (ethertype == ETH_P_PAE)
		return 1;

	return 0;
}

/* Called only as a tasklet (software IRQ), by ieee80211_rx */
static int
ieee80211_rx_frame_decrypt(struct ieee80211_device *ieee, struct sk_buff *skb,
			   struct ieee80211_crypt_data *crypt)
{
	struct ieee80211_hdr_3addr *hdr;
	int res, hdrlen;
	DECLARE_MAC_BUF(mac);

	if (crypt == NULL || crypt->ops->decrypt_mpdu == NULL)
		return 0;

	hdr = (struct ieee80211_hdr_3addr *)skb->data;
	hdrlen = ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_ctl));

	atomic_inc(&crypt->refcnt);
	res = crypt->ops->decrypt_mpdu(skb, hdrlen, crypt->priv);
	atomic_dec(&crypt->refcnt);
	if (res < 0) {
		IEEE80211_DEBUG_DROP("decryption failed (SA=%s"
				     ") res=%d\n", print_mac(mac, hdr->addr2), res);
		if (res == -2)
			IEEE80211_DEBUG_DROP("Decryption failed ICV "
					     "mismatch (key %d)\n",
					     skb->data[hdrlen + 3] >> 6);
		ieee->ieee_stats.rx_discards_undecryptable++;
		return -1;
	}

	return res;
}

/* Called only as a tasklet (software IRQ), by ieee80211_rx */
static int
ieee80211_rx_frame_decrypt_msdu(struct ieee80211_device *ieee,
				struct sk_buff *skb, int keyidx,
				struct ieee80211_crypt_data *crypt)
{
	struct ieee80211_hdr_3addr *hdr;
	int res, hdrlen;
	DECLARE_MAC_BUF(mac);

	if (crypt == NULL || crypt->ops->decrypt_msdu == NULL)
		return 0;

	hdr = (struct ieee80211_hdr_3addr *)skb->data;
	hdrlen = ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_ctl));

	atomic_inc(&crypt->refcnt);
	res = crypt->ops->decrypt_msdu(skb, keyidx, hdrlen, crypt->priv);
	atomic_dec(&crypt->refcnt);
	if (res < 0) {
		printk(KERN_DEBUG "%s: MSDU decryption/MIC verification failed"
		       " (SA=%s keyidx=%d)\n",
		       ieee->dev->name, print_mac(mac, hdr->addr2), keyidx);
		return -1;
	}

	return 0;
}

/* All received frames are sent to this function. @skb contains the frame in
 * IEEE 802.11 format, i.e., in the format it was sent over air.
 * This function is called only as a tasklet (software IRQ). */
int ieee80211_rx(struct ieee80211_device *ieee, struct sk_buff *skb,
		 struct ieee80211_rx_stats *rx_stats)
{
	struct net_device *dev = ieee->dev;
	struct ieee80211_hdr_4addr *hdr;
	size_t hdrlen;
	u16 fc, type, stype, sc;
	struct net_device_stats *stats;
	unsigned int frag;
	u8 *payload;
	u16 ethertype;
#ifdef NOT_YET
	struct net_device *wds = NULL;
	struct sk_buff *skb2 = NULL;
	struct net_device *wds = NULL;
	int frame_authorized = 0;
	int from_assoc_ap = 0;
	void *sta = NULL;
#endif
	u8 dst[ETH_ALEN];
	u8 src[ETH_ALEN];
	struct ieee80211_crypt_data *crypt = NULL;
	int keyidx = 0;
	int can_be_decrypted = 0;
	DECLARE_MAC_BUF(mac);

	hdr = (struct ieee80211_hdr_4addr *)skb->data;
	stats = &ieee->stats;

	if (skb->len < 10) {
		printk(KERN_INFO "%s: SKB length < 10\n", dev->name);
		goto rx_dropped;
	}

	fc = le16_to_cpu(hdr->frame_ctl);
	type = WLAN_FC_GET_TYPE(fc);
	stype = WLAN_FC_GET_STYPE(fc);
	sc = le16_to_cpu(hdr->seq_ctl);
	frag = WLAN_GET_SEQ_FRAG(sc);
	hdrlen = ieee80211_get_hdrlen(fc);

	if (skb->len < hdrlen) {
		printk(KERN_INFO "%s: invalid SKB length %d\n",
			dev->name, skb->len);
		goto rx_dropped;
	}

	/* Put this code here so that we avoid duplicating it in all
	 * Rx paths. - Jean II */
#ifdef CONFIG_WIRELESS_EXT
#ifdef IW_WIRELESS_SPY		/* defined in iw_handler.h */
	/* If spy monitoring on */
	if (ieee->spy_data.spy_number > 0) {
		struct iw_quality wstats;

		wstats.updated = 0;
		if (rx_stats->mask & IEEE80211_STATMASK_RSSI) {
			wstats.level = rx_stats->rssi;
			wstats.updated |= IW_QUAL_LEVEL_UPDATED;
		} else
			wstats.updated |= IW_QUAL_LEVEL_INVALID;

		if (rx_stats->mask & IEEE80211_STATMASK_NOISE) {
			wstats.noise = rx_stats->noise;
			wstats.updated |= IW_QUAL_NOISE_UPDATED;
		} else
			wstats.updated |= IW_QUAL_NOISE_INVALID;

		if (rx_stats->mask & IEEE80211_STATMASK_SIGNAL) {
			wstats.qual = rx_stats->signal;
			wstats.updated |= IW_QUAL_QUAL_UPDATED;
		} else
			wstats.updated |= IW_QUAL_QUAL_INVALID;

		/* Update spy records */
		wireless_spy_update(ieee->dev, hdr->addr2, &wstats);
	}
#endif				/* IW_WIRELESS_SPY */
#endif				/* CONFIG_WIRELESS_EXT */

#ifdef NOT_YET
	hostap_update_rx_stats(local->ap, hdr, rx_stats);
#endif

	if (ieee->iw_mode == IW_MODE_MONITOR) {
		stats->rx_packets++;
		stats->rx_bytes += skb->len;
		ieee80211_monitor_rx(ieee, skb, rx_stats);
		return 1;
	}

	can_be_decrypted = (is_multicast_ether_addr(hdr->addr1) ||
			    is_broadcast_ether_addr(hdr->addr2)) ?
	    ieee->host_mc_decrypt : ieee->host_decrypt;

	if (can_be_decrypted) {
		if (skb->len >= hdrlen + 3) {
			/* Top two-bits of byte 3 are the key index */
			keyidx = skb->data[hdrlen + 3] >> 6;
		}

		/* ieee->crypt[] is WEP_KEY (4) in length.  Given that keyidx
		 * is only allowed 2-bits of storage, no value of keyidx can
		 * be provided via above code that would result in keyidx
		 * being out of range */
		crypt = ieee->crypt[keyidx];

#ifdef NOT_YET
		sta = NULL;

		/* Use station specific key to override default keys if the
		 * receiver address is a unicast address ("individual RA"). If
		 * bcrx_sta_key parameter is set, station specific key is used
		 * even with broad/multicast targets (this is against IEEE
		 * 802.11, but makes it easier to use different keys with
		 * stations that do not support WEP key mapping). */

		if (!(hdr->addr1[0] & 0x01) || local->bcrx_sta_key)
			(void)hostap_handle_sta_crypto(local, hdr, &crypt,
						       &sta);
#endif

		/* allow NULL decrypt to indicate an station specific override
		 * for default encryption */
		if (crypt && (crypt->ops == NULL ||