Subject: mac80211: add beacon configuration via cfg80211 This patch implements the cfg80211 hooks for configuring beaconing on an access point interface in mac80211. While doing so, it fixes a number of races that could badly crash the machine when the beacon is changed while being requested by the driver. Signed-off-by: Johannes Berg --- The dtim_count field should possibly also be part of the beacon structure, but the possible race there doesn't really matter, worst thing is that one beacon will be sent with a wrong dtim count if (and only if) userspace changes the dtim period during operation. net/mac80211/cfg.c | 156 +++++++++++++++++++++++++++++++++++++++++ net/mac80211/debugfs_netdev.c | 27 ------- net/mac80211/ieee80211_i.h | 14 ++- net/mac80211/ieee80211_iface.c | 4 - net/mac80211/tx.c | 63 ++++++++++------ 5 files changed, 204 insertions(+), 60 deletions(-) Index: mac80211/net/mac80211/cfg.c =================================================================== --- mac80211.orig/net/mac80211/cfg.c 2007-11-11 15:17:12.837164411 +0100 +++ mac80211/net/mac80211/cfg.c 2007-11-11 15:18:36.853952256 +0100 @@ -9,6 +9,7 @@ #include #include #include +#include #include #include "ieee80211_i.h" #include "cfg.h" @@ -274,6 +275,158 @@ return 0; } +/* + * This handles both adding a beacon and setting new beacon info + */ +static int ieee80211_config_beacon(struct ieee80211_sub_if_data *sdata, + struct beacon_parameters *params) +{ + struct beacon_data *new, *old; + int new_head_len, new_tail_len; + int size; + int err = -EINVAL; + + old = sdata->u.ap.beacon; + + /* head must not be zero-length */ + if (params->head && !params->head_len) + return -EINVAL; + + /* + * This is a kludge. beacon interval should really be part + * of the beacon information. + */ + if (params->interval) { + sdata->local->hw.conf.beacon_int = params->interval; + if (ieee80211_hw_config(sdata->local)) + return -EINVAL; + /* + * We updated some parameter so if below bails out + * it's not an error. + */ + err = 0; + } + + /* Need to have a beacon head if we don't have one yet */ + if (!params->head && !old) + return err; + + /* sorry, no way to start beaconing without dtim period */ + if (!params->dtim_period && !old) + return err; + + /* new or old head? */ + if (params->head) + new_head_len = params->head_len; + else + new_head_len = old->head_len; + + /* new or old tail? */ + if (params->tail || !old) + /* params->tail_len will be zero for !params->tail */ + new_tail_len = params->tail_len; + else + new_tail_len = old->tail_len; + + size = sizeof(*new) + new_head_len + new_tail_len; + + new = kzalloc(size, GFP_KERNEL); + if (!new) + return -ENOMEM; + + /* start filling the new info now */ + + /* new or old dtim period? */ + if (params->dtim_period) + new->dtim_period = params->dtim_period; + else + new->dtim_period = old->dtim_period; + + /* + * pointers go into the block we allocated, + * memory is | beacon_data | head | tail | + */ + new->head = ((u8 *) new) + sizeof(*new); + new->tail = new->head + new_head_len; + new->head_len = new_head_len; + new->tail_len = new_tail_len; + + /* copy in head */ + if (params->head) + memcpy(new->head, params->head, new_head_len); + else + memcpy(new->head, old->head, new_head_len); + + /* copy in optional tail */ + if (params->tail) + memcpy(new->tail, params->tail, new_tail_len); + else + if (old) + memcpy(new->tail, old->tail, new_tail_len); + + rcu_assign_pointer(sdata->u.ap.beacon, new); + + synchronize_rcu(); + + kfree(old); + + return ieee80211_if_config_beacon(sdata->dev); +} + +static int ieee80211_add_beacon(struct wiphy *wiphy, struct net_device *dev, + struct beacon_parameters *params) +{ + struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev); + struct beacon_data *old; + + if (sdata->type != IEEE80211_IF_TYPE_AP) + return -EINVAL; + + old = sdata->u.ap.beacon; + + if (old) + return -EALREADY; + + return ieee80211_config_beacon(sdata, params); +} + +static int ieee80211_set_beacon(struct wiphy *wiphy, struct net_device *dev, + struct beacon_parameters *params) +{ + struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev); + struct beacon_data *old; + + if (sdata->type != IEEE80211_IF_TYPE_AP) + return -EINVAL; + + old = sdata->u.ap.beacon; + + if (!old) + return -ENOENT; + + return ieee80211_config_beacon(sdata, params); +} + +static int ieee80211_del_beacon(struct wiphy *wiphy, struct net_device *dev) +{ + struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev); + struct beacon_data *old; + + if (sdata->type != IEEE80211_IF_TYPE_AP) + return -EINVAL; + + old = sdata->u.ap.beacon; + + if (!old) + return -ENOENT; + + rcu_assign_pointer(sdata->u.ap.beacon, NULL); + synchronize_rcu(); + kfree(old); + + return ieee80211_if_config_beacon(dev); +} + struct cfg80211_ops mac80211_config_ops = { .add_virtual_intf = ieee80211_add_iface, .del_virtual_intf = ieee80211_del_iface, @@ -282,4 +435,7 @@ .del_key = ieee80211_del_key, .get_key = ieee80211_get_key, .set_default_key = ieee80211_config_default_key, + .add_beacon = ieee80211_add_beacon, + .set_beacon = ieee80211_set_beacon, + .del_beacon = ieee80211_del_beacon, }; Index: mac80211/net/mac80211/debugfs_netdev.c =================================================================== --- mac80211.orig/net/mac80211/debugfs_netdev.c 2007-10-14 00:42:30.054156000 +0200 +++ mac80211/net/mac80211/debugfs_netdev.c 2007-11-11 15:18:11.852527505 +0100 @@ -124,7 +124,6 @@ /* AP attributes */ IEEE80211_IF_FILE(num_sta_ps, u.ap.num_sta_ps, ATOMIC); -IEEE80211_IF_FILE(dtim_period, u.ap.dtim_period, DEC); IEEE80211_IF_FILE(dtim_count, u.ap.dtim_count, DEC); IEEE80211_IF_FILE(num_beacons, u.ap.num_beacons, DEC); IEEE80211_IF_FILE(force_unicast_rateidx, u.ap.force_unicast_rateidx, DEC); @@ -138,26 +137,6 @@ } __IEEE80211_IF_FILE(num_buffered_multicast); -static ssize_t ieee80211_if_fmt_beacon_head_len( - const struct ieee80211_sub_if_data *sdata, char *buf, int buflen) -{ - if (sdata->u.ap.beacon_head) - return scnprintf(buf, buflen, "%d\n", - sdata->u.ap.beacon_head_len); - return scnprintf(buf, buflen, "\n"); -} -__IEEE80211_IF_FILE(beacon_head_len); - -static ssize_t ieee80211_if_fmt_beacon_tail_len( - const struct ieee80211_sub_if_data *sdata, char *buf, int buflen) -{ - if (sdata->u.ap.beacon_tail) - return scnprintf(buf, buflen, "%d\n", - sdata->u.ap.beacon_tail_len); - return scnprintf(buf, buflen, "\n"); -} -__IEEE80211_IF_FILE(beacon_tail_len); - /* WDS attributes */ IEEE80211_IF_FILE(peer, u.wds.remote_addr, MAC); @@ -194,14 +173,11 @@ DEBUGFS_ADD(eapol, ap); DEBUGFS_ADD(ieee8021_x, ap); DEBUGFS_ADD(num_sta_ps, ap); - DEBUGFS_ADD(dtim_period, ap); DEBUGFS_ADD(dtim_count, ap); DEBUGFS_ADD(num_beacons, ap); DEBUGFS_ADD(force_unicast_rateidx, ap); DEBUGFS_ADD(max_ratectrl_rateidx, ap); DEBUGFS_ADD(num_buffered_multicast, ap); - DEBUGFS_ADD(beacon_head_len, ap); - DEBUGFS_ADD(beacon_tail_len, ap); } static void add_wds_files(struct ieee80211_sub_if_data *sdata) @@ -287,14 +263,11 @@ DEBUGFS_DEL(eapol, ap); DEBUGFS_DEL(ieee8021_x, ap); DEBUGFS_DEL(num_sta_ps, ap); - DEBUGFS_DEL(dtim_period, ap); DEBUGFS_DEL(dtim_count, ap); DEBUGFS_DEL(num_beacons, ap); DEBUGFS_DEL(force_unicast_rateidx, ap); DEBUGFS_DEL(max_ratectrl_rateidx, ap); DEBUGFS_DEL(num_buffered_multicast, ap); - DEBUGFS_DEL(beacon_head_len, ap); - DEBUGFS_DEL(beacon_tail_len, ap); } static void del_wds_files(struct ieee80211_sub_if_data *sdata) Index: mac80211/net/mac80211/ieee80211_i.h =================================================================== --- mac80211.orig/net/mac80211/ieee80211_i.h 2007-11-11 15:15:53.792659922 +0100 +++ mac80211/net/mac80211/ieee80211_i.h 2007-11-11 15:18:11.864528190 +0100 @@ -190,9 +190,14 @@ typedef ieee80211_txrx_result (*ieee80211_rx_handler) (struct ieee80211_txrx_data *rx); +struct beacon_data { + u8 *head, *tail; + int head_len, tail_len; + int dtim_period; +}; + struct ieee80211_if_ap { - u8 *beacon_head, *beacon_tail; - int beacon_head_len, beacon_tail_len; + struct beacon_data *beacon; struct list_head vlans; @@ -205,7 +210,7 @@ u8 tim[sizeof(unsigned long) * BITS_TO_LONGS(IEEE80211_MAX_AID + 1)]; atomic_t num_sta_ps; /* number of stations in PS mode */ struct sk_buff_head ps_bc_buf; - int dtim_period, dtim_count; + int dtim_count; int force_unicast_rateidx; /* forced TX rateidx for unicast frames */ int max_ratectrl_rateidx; /* max TX rateidx for rate control */ int num_beacons; /* number of TXed beacon frames for this BSS */ @@ -361,14 +366,11 @@ struct dentry *eapol; struct dentry *ieee8021_x; struct dentry *num_sta_ps; - struct dentry *dtim_period; struct dentry *dtim_count; struct dentry *num_beacons; struct dentry *force_unicast_rateidx; struct dentry *max_ratectrl_rateidx; struct dentry *num_buffered_multicast; - struct dentry *beacon_head_len; - struct dentry *beacon_tail_len; } ap; struct { struct dentry *channel_use; Index: mac80211/net/mac80211/ieee80211_iface.c =================================================================== --- mac80211.orig/net/mac80211/ieee80211_iface.c 2007-11-11 15:15:53.796660158 +0100 +++ mac80211/net/mac80211/ieee80211_iface.c 2007-11-11 15:18:11.868528415 +0100 @@ -187,7 +187,6 @@ sdata->u.vlan.ap = NULL; break; case IEEE80211_IF_TYPE_AP: - sdata->u.ap.dtim_period = 2; sdata->u.ap.force_unicast_rateidx = -1; sdata->u.ap.max_ratectrl_rateidx = -1; skb_queue_head_init(&sdata->u.ap.ps_bc_buf); @@ -271,8 +270,7 @@ } } - kfree(sdata->u.ap.beacon_head); - kfree(sdata->u.ap.beacon_tail); + kfree(sdata->u.ap.beacon); while ((skb = skb_dequeue(&sdata->u.ap.ps_bc_buf))) { local->total_ps_buffered--; Index: mac80211/net/mac80211/tx.c =================================================================== --- mac80211.orig/net/mac80211/tx.c 2007-11-11 15:15:53.804660611 +0100 +++ mac80211/net/mac80211/tx.c 2007-11-11 15:18:11.868528415 +0100 @@ -1656,7 +1656,8 @@ static void ieee80211_beacon_add_tim(struct ieee80211_local *local, struct ieee80211_if_ap *bss, - struct sk_buff *skb) + struct sk_buff *skb, + struct beacon_data *beacon) { u8 *pos, *tim; int aid0 = 0; @@ -1672,7 +1673,7 @@ IEEE80211_MAX_AID+1); if (bss->dtim_count == 0) - bss->dtim_count = bss->dtim_period - 1; + bss->dtim_count = beacon->dtim_period - 1; else bss->dtim_count--; @@ -1680,7 +1681,7 @@ *pos++ = WLAN_EID_TIM; *pos++ = 4; *pos++ = bss->dtim_count; - *pos++ = bss->dtim_period; + *pos++ = beacon->dtim_period; if (bss->dtim_count == 0 && !skb_queue_empty(&bss->ps_bc_buf)) aid0 = 1; @@ -1728,8 +1729,9 @@ struct ieee80211_if_ap *ap = NULL; struct ieee80211_rate *rate; struct rate_control_extra extra; - u8 *b_head, *b_tail; - int bh_len, bt_len; + struct beacon_data *beacon; + + rcu_read_lock(); bdev = dev_get_by_index(if_id); if (bdev) { @@ -1738,37 +1740,35 @@ dev_put(bdev); } - if (!ap || sdata->type != IEEE80211_IF_TYPE_AP || - !ap->beacon_head) { + beacon = rcu_dereference(ap->beacon); + + if (!ap || sdata->type != IEEE80211_IF_TYPE_AP || !beacon) { #ifdef CONFIG_MAC80211_VERBOSE_DEBUG if (net_ratelimit()) printk(KERN_DEBUG "no beacon data avail for idx=%d " "(%s)\n", if_id, bdev ? bdev->name : "N/A"); #endif /* CONFIG_MAC80211_VERBOSE_DEBUG */ - return NULL; + skb = NULL; + goto out; } - /* Assume we are generating the normal beacon locally */ - b_head = ap->beacon_head; - b_tail = ap->beacon_tail; - bh_len = ap->beacon_head_len; - bt_len = ap->beacon_tail_len; - - skb = dev_alloc_skb(local->tx_headroom + - bh_len + bt_len + 256 /* maximum TIM len */); + /* headroom, head length, tail length and maximum TIM length */ + skb = dev_alloc_skb(local->tx_headroom + beacon->head_len + + beacon->tail_len + 256); if (!skb) - return NULL; + goto out; skb_reserve(skb, local->tx_headroom); - memcpy(skb_put(skb, bh_len), b_head, bh_len); + memcpy(skb_put(skb, beacon->head_len), beacon->head, + beacon->head_len); ieee80211_include_sequence(sdata, (struct ieee80211_hdr *)skb->data); - ieee80211_beacon_add_tim(local, ap, skb); + ieee80211_beacon_add_tim(local, ap, skb, beacon); - if (b_tail) { - memcpy(skb_put(skb, bt_len), b_tail, bt_len); - } + if (beacon->tail) + memcpy(skb_put(skb, beacon->tail_len), beacon->tail, + beacon->tail_len); if (control) { memset(&extra, 0, sizeof(extra)); @@ -1781,7 +1781,8 @@ "found\n", wiphy_name(local->hw.wiphy)); } dev_kfree_skb(skb); - return NULL; + skb = NULL; + goto out; } control->tx_rate = @@ -1796,6 +1797,9 @@ } ap->num_beacons++; + + out: + rcu_read_unlock(); return skb; } EXPORT_SYMBOL(ieee80211_beacon_get); @@ -1844,6 +1848,7 @@ struct net_device *bdev; struct ieee80211_sub_if_data *sdata; struct ieee80211_if_ap *bss = NULL; + struct beacon_data *beacon; bdev = dev_get_by_index(if_id); if (bdev) { @@ -1851,9 +1856,19 @@ bss = &sdata->u.ap; dev_put(bdev); } - if (!bss || sdata->type != IEEE80211_IF_TYPE_AP || !bss->beacon_head) + + if (!bss) return NULL; + rcu_read_lock(); + beacon = rcu_dereference(bss->beacon); + + if (sdata->type != IEEE80211_IF_TYPE_AP || !beacon || !beacon->head) { + rcu_read_unlock(); + return NULL; + } + rcu_read_unlock(); + if (bss->dtim_count != 0) return NULL; /* send buffered bc/mc only after DTIM beacon */ memset(control, 0, sizeof(*control));