From cb17ed29a7a5fea8c9bf70e8a05757d71650e025 Mon Sep 17 00:00:00 2001 From: Mathy Vanhoef Date: Thu, 23 Jul 2020 14:01:53 +0400 Subject: [PATCH] mac80211: parse radiotap header when selecting Tx queue Already parse the radiotap header in ieee80211_monitor_select_queue. In a subsequent commit this will allow us to add a radiotap flag that influences the queue on which injected packets will be sent. This also fixes the incomplete validation of the injected frame in ieee80211_monitor_select_queue: currently an out of bounds memory access may occur in in the called function ieee80211_select_queue_80211 if the 802.11 header is too small. Note that in ieee80211_monitor_start_xmit the radiotap header is parsed again, which is necessairy because ieee80211_monitor_select_queue is not always called beforehand. Signed-off-by: Mathy Vanhoef Link: https://lore.kernel.org/r/20200723100153.31631-6-Mathy.Vanhoef@kuleuven.be Signed-off-by: Johannes Berg --- include/net/mac80211.h | 8 ++++++++ net/mac80211/iface.c | 15 ++++++++++---- net/mac80211/tx.c | 54 ++++++++++++++++++++++---------------------------- 3 files changed, 43 insertions(+), 34 deletions(-) diff --git a/include/net/mac80211.h b/include/net/mac80211.h index 21ce821..6e26f0b 100644 --- a/include/net/mac80211.h +++ b/include/net/mac80211.h @@ -6239,6 +6239,14 @@ bool ieee80211_tx_prepare_skb(struct ieee80211_hw *hw, int band, struct ieee80211_sta **sta); /** + * Sanity-check and parse the radiotap header of injected frames + * @skb: packet injected by userspace + * @dev: the &struct device of this 802.11 device + */ +bool ieee80211_parse_tx_radiotap(struct sk_buff *skb, + struct net_device *dev); + +/** * struct ieee80211_noa_data - holds temporary data for tracking P2P NoA state * * @next_tsf: TSF timestamp of the next absent state change diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c index 570f818..9740ae8 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -1183,17 +1183,24 @@ static u16 ieee80211_monitor_select_queue(struct net_device *dev, { struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev); struct ieee80211_local *local = sdata->local; + struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); struct ieee80211_hdr *hdr; - struct ieee80211_radiotap_header *rtap = (void *)skb->data; + int len_rthdr; if (local->hw.queues < IEEE80211_NUM_ACS) return 0; - if (skb->len < 4 || - skb->len < le16_to_cpu(rtap->it_len) + 2 /* frame control */) + /* reset flags and info before parsing radiotap header */ + memset(info, 0, sizeof(*info)); + + if (!ieee80211_parse_tx_radiotap(skb, dev)) return 0; /* doesn't matter, frame will be dropped */ - hdr = (void *)((u8 *)skb->data + le16_to_cpu(rtap->it_len)); + len_rthdr = ieee80211_get_radiotap_len(skb->data); + hdr = (struct ieee80211_hdr *)(skb->data + len_rthdr); + if (skb->len < len_rthdr + 2 || + skb->len < len_rthdr + ieee80211_hdrlen(hdr->frame_control)) + return 0; /* doesn't matter, frame will be dropped */ return ieee80211_select_queue_80211(sdata, skb, hdr); } diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 7fb4afa..ec35a92 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -2015,9 +2015,10 @@ void ieee80211_xmit(struct ieee80211_sub_if_data *sdata, ieee80211_tx(sdata, sta, skb, false); } -static bool ieee80211_parse_tx_radiotap(struct ieee80211_local *local, - struct sk_buff *skb) +bool ieee80211_parse_tx_radiotap(struct sk_buff *skb, + struct net_device *dev) { + struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr); struct ieee80211_radiotap_iterator iterator; struct ieee80211_radiotap_header *rthdr = (struct ieee80211_radiotap_header *) skb->data; @@ -2036,6 +2037,18 @@ static bool ieee80211_parse_tx_radiotap(struct ieee80211_local *local, u8 vht_mcs = 0, vht_nss = 0; int i; + /* check for not even having the fixed radiotap header part */ + if (unlikely(skb->len < sizeof(struct ieee80211_radiotap_header))) + return false; /* too short to be possibly valid */ + + /* is it a header version we can trust to find length from? */ + if (unlikely(rthdr->it_version)) + return false; /* only version 0 is supported */ + + /* does the skb contain enough to deliver on the alleged length? */ + if (unlikely(skb->len < ieee80211_get_radiotap_len(skb->data))) + return false; /* skb too short for claimed rt header extent */ + info->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT | IEEE80211_TX_CTL_DONTFRAG; @@ -2189,13 +2202,6 @@ static bool ieee80211_parse_tx_radiotap(struct ieee80211_local *local, local->hw.max_rate_tries); } - /* - * remove the radiotap header - * iterator->_max_length was sanity-checked against - * skb->len by iterator init - */ - skb_pull(skb, iterator._max_length); - return true; } @@ -2204,8 +2210,6 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb, { struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr); struct ieee80211_chanctx_conf *chanctx_conf; - struct ieee80211_radiotap_header *prthdr = - (struct ieee80211_radiotap_header *)skb->data; struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); struct ieee80211_hdr *hdr; struct ieee80211_sub_if_data *tmp_sdata, *sdata; @@ -2213,21 +2217,17 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb, u16 len_rthdr; int hdrlen; - /* check for not even having the fixed radiotap header part */ - if (unlikely(skb->len < sizeof(struct ieee80211_radiotap_header))) - goto fail; /* too short to be possibly valid */ + memset(info, 0, sizeof(*info)); + info->flags = IEEE80211_TX_CTL_REQ_TX_STATUS | + IEEE80211_TX_CTL_INJECTED; - /* is it a header version we can trust to find length from? */ - if (unlikely(prthdr->it_version)) - goto fail; /* only version 0 is supported */ + /* Sanity-check and process the injection radiotap header */ + if (!ieee80211_parse_tx_radiotap(skb, dev)) + goto fail; - /* then there must be a radiotap header with a length we can use */ + /* we now know there is a radiotap header with a length we can use */ len_rthdr = ieee80211_get_radiotap_len(skb->data); - /* does the skb contain enough to deliver on the alleged length? */ - if (unlikely(skb->len < len_rthdr)) - goto fail; /* skb too short for claimed rt header extent */ - /* * fix up the pointers accounting for the radiotap * header still being in there. We are being given @@ -2273,11 +2273,6 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb, skb->priority = *p & IEEE80211_QOS_CTL_TAG1D_MASK; } - memset(info, 0, sizeof(*info)); - - info->flags = IEEE80211_TX_CTL_REQ_TX_STATUS | - IEEE80211_TX_CTL_INJECTED; - rcu_read_lock(); /* @@ -2343,9 +2338,8 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb, info->band = chandef->chan->band; - /* process and remove the injection radiotap header */ - if (!ieee80211_parse_tx_radiotap(local, skb)) - goto fail_rcu; + /* remove the injection radiotap header */ + skb_pull(skb, len_rthdr); ieee80211_xmit(sdata, NULL, skb); rcu_read_unlock(); -- 2.7.4