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

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SVN-Revision: 14225
This commit is contained in:
Felix Fietkau 2009-01-27 20:05:46 +00:00
parent fe48f4cac0
commit 9bb8734d2e
1 changed files with 184 additions and 0 deletions
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184
package/hostapd/patches/110-nl80211_socketfilter.patch Normal file
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@ -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");