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Message-Id: <20170412110726.9689-3-johannes@sipsolutions.net>
Date: Wed, 12 Apr 2017 13:07:26 +0200
From: Johannes Berg <johannes@...solutions.net>
To: linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Cc: Johannes Berg <johannes.berg@...el.com>
Subject: [RFC 3/3] mac80211: support bpf monitor filter
From: Johannes Berg <johannes.berg@...el.com>
Add the necessary hooks for running monitor filter programs
in mac80211's RX path, before a frame is handed off to a
monitor interface. If the frame isn't accepted then this
will save the overhead of creating a new SKB and building
the radiotap header.
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
net/mac80211/Kconfig | 1 +
net/mac80211/cfg.c | 13 +++++++++++++
net/mac80211/ieee80211_i.h | 6 ++++++
net/mac80211/iface.c | 9 ++++++++-
net/mac80211/main.c | 3 +++
net/mac80211/rx.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 76 insertions(+), 1 deletion(-)
diff --git a/net/mac80211/Kconfig b/net/mac80211/Kconfig
index 76e30f4797fb..080e0c705c72 100644
--- a/net/mac80211/Kconfig
+++ b/net/mac80211/Kconfig
@@ -8,6 +8,7 @@ config MAC80211
select CRYPTO_GCM
select CRYPTO_CMAC
select CRC32
+ select WANT_BPF_WIFIMON
---help---
This option enables the hardware independent IEEE 802.11
networking stack.
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 4ff03c88022e..c394c08ed0e0 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -106,6 +106,19 @@ static int ieee80211_set_mon_options(struct ieee80211_sub_if_data *sdata,
}
}
+ if (params->filter) {
+ struct bpf_prog *old = rtnl_dereference(sdata->u.mntr.filter);
+
+ if (IS_ERR(params->filter))
+ RCU_INIT_POINTER(sdata->u.mntr.filter, NULL);
+ else
+ rcu_assign_pointer(sdata->u.mntr.filter,
+ params->filter);
+
+ if (old)
+ bpf_prog_put(old);
+ }
+
return 0;
}
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 0e718437d080..06a2e2cdde83 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -27,6 +27,8 @@
#include <linux/leds.h>
#include <linux/idr.h>
#include <linux/rhashtable.h>
+#include <linux/filter.h>
+#include <linux/bpf.h>
#include <net/ieee80211_radiotap.h>
#include <net/cfg80211.h>
#include <net/mac80211.h>
@@ -839,6 +841,10 @@ struct txq_info {
struct ieee80211_if_mntr {
u32 flags;
u8 mu_follow_addr[ETH_ALEN] __aligned(2);
+#ifdef CONFIG_BPF_WIFIMON
+ struct bpf_prog *filter;
+ bool deliver;
+#endif
};
/**
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 5bb0c5012819..05258fd9dda2 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1107,8 +1107,15 @@ static void ieee80211_teardown_sdata(struct ieee80211_sub_if_data *sdata)
__skb_queue_purge(&sdata->fragments[i].skb_list);
sdata->fragment_next = 0;
- if (ieee80211_vif_is_mesh(&sdata->vif))
+ if (ieee80211_vif_is_mesh(&sdata->vif)) {
ieee80211_mesh_teardown_sdata(sdata);
+ } else if (sdata->vif.type == NL80211_IFTYPE_MONITOR) {
+ struct bpf_prog *old = rtnl_dereference(sdata->u.mntr.filter);
+
+ RCU_INIT_POINTER(sdata->u.mntr.filter, NULL);
+ if (old)
+ bpf_prog_put(old);
+ }
}
static void ieee80211_uninit(struct net_device *dev)
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 56fb47953b72..e9d13dedcca4 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -551,6 +551,9 @@ struct ieee80211_hw *ieee80211_alloc_hw_nm(size_t priv_data_len,
NL80211_FEATURE_FULL_AP_CLIENT_STATE;
wiphy_ext_feature_set(wiphy, NL80211_EXT_FEATURE_FILS_STA);
+ if (IS_ENABLED(CONFIG_BPF_WIFIMON))
+ wiphy_ext_feature_isset(wiphy, NL80211_EXT_FEATURE_WIFIMON_BPF);
+
if (!ops->hw_scan)
wiphy->features |= NL80211_FEATURE_LOW_PRIORITY_SCAN |
NL80211_FEATURE_AP_SCAN;
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 335c7843169f..8c811deaf3cd 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -508,6 +508,7 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
struct ieee80211_mgmt *mgmt;
struct ieee80211_sub_if_data *monitor_sdata =
rcu_dereference(local->monitor_sdata);
+ bool deliver __maybe_unused = false;
if (unlikely(status->flag & RX_FLAG_RADIOTAP_VENDOR_DATA)) {
struct ieee80211_vendor_radiotap *rtap = (void *)origskb->data;
@@ -552,6 +553,45 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
return origskb;
}
+#ifdef CONFIG_BPF_WIFIMON
+ /* pretend all the monitor info isn't there */
+ __pskb_pull(origskb, rtap_vendor_space);
+ origskb->len -= present_fcs_len;
+
+ list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+ const struct bpf_prog *filter;
+
+ if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
+ continue;
+
+ if (sdata->u.mntr.flags & MONITOR_FLAG_COOK_FRAMES)
+ continue;
+
+ if (!ieee80211_sdata_running(sdata))
+ continue;
+
+ filter = rcu_dereference(sdata->u.mntr.filter);
+ if (filter) {
+ sdata->u.mntr.deliver = BPF_PROG_RUN(filter, origskb);
+ if (sdata->u.mntr.deliver)
+ deliver = true;
+ } else {
+ sdata->u.mntr.deliver = true;
+ deliver = true;
+ }
+ }
+
+ /* stop pretending the monitor info isn't there */
+ origskb->len += present_fcs_len;
+ __skb_push(origskb, rtap_vendor_space);
+
+ if (!deliver) {
+ remove_monitor_info(local, origskb, present_fcs_len,
+ rtap_vendor_space);
+ return origskb;
+ }
+#endif
+
/* room for the radiotap header based on driver features */
rt_hdrlen = ieee80211_rx_radiotap_hdrlen(local, status, origskb);
needed_headroom = rt_hdrlen - rtap_vendor_space;
@@ -598,11 +638,16 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
continue;
+#ifdef CONFIG_BPF_WIFIMON
+ if (!sdata->u.mntr.deliver)
+ continue;
+#else
if (sdata->u.mntr.flags & MONITOR_FLAG_COOK_FRAMES)
continue;
if (!ieee80211_sdata_running(sdata))
continue;
+#endif
if (prev_dev) {
skb2 = skb_clone(skb, GFP_ATOMIC);
--
2.11.0
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