--- /dev/null
+--- 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");
projects / openwrt.git / commitdiff