hostapd: add support for socket filtering to get rid of some of the massive cpu overhead with mac80211 drivers (backport from hostapd git repository)

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@14225 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 184 insertions, 0 deletions

diff --git a/package/hostapd/patches/110-nl80211_socketfilter.patch b/package/hostapd/patches/110-nl80211_socketfilter.patch
new file mode 100644
index 000000000..4427d0061
--- /dev/null
+++ b/package/hostapd/patches/110-nl80211_socketfilter.patch
@@ -0,0 +1,184 @@
+--- a/hostapd/driver_nl80211.c
++++ b/hostapd/driver_nl80211.c
+@@ -27,6 +27,7 @@
+ #include <net/if.h>
+ #include <netpacket/packet.h>
+ #include "wireless_copy.h"
++#include <linux/filter.h>
+ #include <net/if_arp.h>
+ 
+ #include "hostapd.h"
+@@ -1728,6 +1729,9 @@ static void handle_frame(struct hostapd_
+ 		case WLAN_FC_TODS:
+ 			bssid = hdr->addr1;
+ 			break;
++		case WLAN_FC_FROMDS:
++			bssid = hdr->addr2;
++			break;
+ 		default:
+ 			/* discard */
+ 			return;
+@@ -1908,6 +1912,150 @@ static void handle_monitor_read(int sock
+ }
+ 
+ 
++/*
++ * we post-process the filter code later and rewrite
++ * this to the offset to the last instruction
++ */
++#define PASS	0xFF
++#define FAIL	0xFE
++
++static struct sock_filter msock_filter_insns[] = {
++	/*
++	 * do a little-endian load of the radiotap length field
++	 */
++	/* load lower byte into A */
++	BPF_STMT(BPF_LD  | BPF_B | BPF_ABS, 2),
++	/* put it into X (== index register) */
++	BPF_STMT(BPF_MISC| BPF_TAX, 0),
++	/* load upper byte into A */
++	BPF_STMT(BPF_LD  | BPF_B | BPF_ABS, 3),
++	/* left-shift it by 8 */
++	BPF_STMT(BPF_ALU | BPF_LSH | BPF_K, 8),
++	/* or with X */
++	BPF_STMT(BPF_ALU | BPF_OR | BPF_X, 0),
++	/* put result into X */
++	BPF_STMT(BPF_MISC| BPF_TAX, 0),
++
++	/*
++	 * Allow management frames through, this also gives us those
++	 * management frames that we sent ourselves with status
++	 */
++	/* load the lower byte of the IEEE 802.11 frame control field */
++	BPF_STMT(BPF_LD  | BPF_B | BPF_IND, 0),
++	/* mask off frame type and version */
++	BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0xF),
++	/* accept frame if it's both 0, fall through otherwise */
++	BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0, PASS, 0),
++
++	/*
++	 * TODO: add a bit to radiotap RX flags that indicates
++	 * that the sending station is not associated, then
++	 * add a filter here that filters on our DA and that flag
++	 * to allow us to deauth frames to that bad station.
++	 *
++	 * Not a regression -- we didn't do it before either.
++	 */
++
++#if 0
++	/*
++	 * drop non-data frames, WDS frames
++	 */
++	/* load the lower byte of the frame control field */
++	BPF_STMT(BPF_LD   | BPF_B | BPF_IND, 0),
++	/* mask off QoS bit */
++	BPF_STMT(BPF_ALU  | BPF_AND | BPF_K, 0x0c),
++	/* drop non-data frames */
++	BPF_JUMP(BPF_JMP  | BPF_JEQ | BPF_K, 8, 0, FAIL),
++	/* load the upper byte of the frame control field */
++	BPF_STMT(BPF_LD   | BPF_B | BPF_IND, 0),
++	/* mask off toDS/fromDS */
++	BPF_STMT(BPF_ALU  | BPF_AND | BPF_K, 0x03),
++	/* drop WDS frames */
++	BPF_JUMP(BPF_JMP  | BPF_JEQ | BPF_K, 3, FAIL, 0),
++#endif
++
++	/*
++	 * add header length to index
++	 */
++	/* load the lower byte of the frame control field */
++	BPF_STMT(BPF_LD   | BPF_B | BPF_IND, 0),
++	/* mask off QoS bit */
++	BPF_STMT(BPF_ALU  | BPF_AND | BPF_K, 0x80),
++	/* right shift it by 6 to give 0 or 2 */
++	BPF_STMT(BPF_ALU  | BPF_RSH | BPF_K, 6),
++	/* add data frame header length */
++	BPF_STMT(BPF_ALU  | BPF_ADD | BPF_K, 24),
++	/* add index, was start of 802.11 header */
++	BPF_STMT(BPF_ALU  | BPF_ADD | BPF_X, 0),
++	/* move to index, now start of LL header */
++	BPF_STMT(BPF_MISC | BPF_TAX, 0),
++
++	/*
++	 * Accept empty data frames, we use those for
++	 * polling activity.
++	 */
++	BPF_STMT(BPF_LD  | BPF_W | BPF_LEN, 0),
++	BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_X, 0, PASS, 0),
++
++	/*
++	 * Accept EAPOL frames
++	 */
++	BPF_STMT(BPF_LD  | BPF_W | BPF_IND, 0),
++	BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0xAAAA0300, 0, FAIL),
++	BPF_STMT(BPF_LD  | BPF_W | BPF_IND, 4),
++	BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0x0000888E, PASS, FAIL),
++
++	/* keep these last two statements or change the code below */
++	/* return 0 == "DROP" */
++	BPF_STMT(BPF_RET | BPF_K, 0),
++	/* return ~0 == "keep all" */
++	BPF_STMT(BPF_RET | BPF_K, ~0),
++};
++
++static struct sock_fprog msock_filter = {
++	.len = sizeof(msock_filter_insns)/sizeof(msock_filter_insns[0]),
++	.filter = msock_filter_insns,
++};
++
++
++static int add_monitor_filter(int s)
++{
++	int idx;
++
++	/* rewrite all PASS/FAIL jump offsets */
++	for (idx = 0; idx < msock_filter.len; idx++) {
++		struct sock_filter *insn = &msock_filter_insns[idx];
++
++		if (BPF_CLASS(insn->code) == BPF_JMP) {
++			if (insn->code == (BPF_JMP|BPF_JA)) {
++				if (insn->k == PASS)
++					insn->k = msock_filter.len - idx - 2;
++				else if (insn->k == FAIL)
++					insn->k = msock_filter.len - idx - 3;
++			}
++
++			if (insn->jt == PASS)
++				insn->jt = msock_filter.len - idx - 2;
++			else if (insn->jt == FAIL)
++				insn->jt = msock_filter.len - idx - 3;
++
++			if (insn->jf == PASS)
++				insn->jf = msock_filter.len - idx - 2;
++			else if (insn->jf == FAIL)
++				insn->jf = msock_filter.len - idx - 3;
++		}
++	}
++
++	if (setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER,
++		       &msock_filter, sizeof(msock_filter))) {
++		perror("SO_ATTACH_FILTER");
++		return -1;
++	}
++
++	return 0;
++}
++
++
+ static int nl80211_create_monitor_interface(struct i802_driver_data *drv)
+ {
+ 	char buf[IFNAMSIZ];
+@@ -1936,6 +2084,12 @@ static int nl80211_create_monitor_interf
+ 		goto error;
+ 	}
+ 
++	if (add_monitor_filter(drv->monitor_sock)) {
++		wpa_printf(MSG_INFO, "Failed to set socket filter for monitor "
++			   "interface; do filtering in user space");
++		/* This works, but will cost in performance. */
++	}
++
+ 	if (bind(drv->monitor_sock, (struct sockaddr *) &ll,
+ 		 sizeof(ll)) < 0) {
+ 		perror("monitor socket bind");