From d4306feb76ee9a6d9ecee63b152404bd0db0f97c Mon Sep 17 00:00:00 2001

From: Michal Sekletar <msekleta@redhat.com>

Date: Tue, 5 Aug 2014 16:46:19 +0200

Subject: [PATCH] Introduce bpf_filter1 function

Function takes additional argument which is a pointer to bpf_aux_data

structure. This newly introduced struct holds auxiliary data provided by caller

to specify additional data needed to implement some BPF extensions while

executing filter in userspace.

bpf_filter1 currently implements support for two BPF extesions, namely

vlan_tci and vlan_pr.

(cherry picked from 02e420f820750e970c93068c01ea10d4c16f2b9a)

Conflicts:

        bpf/net/bpf_filter.c

---

 bpf/net/bpf_filter.c | 77 +++++++++++++++++++++++++++++++++++++++++++---------

 pcap/bpf.h           | 10 +++++++

 2 files changed, 74 insertions(+), 13 deletions(-)

diff --git a/bpf/net/bpf_filter.c b/bpf/net/bpf_filter.c

index 0c4fb00..3409a9b 100644

--- a/bpf/net/bpf_filter.c

+++ b/bpf/net/bpf_filter.c

@@ -200,6 +200,17 @@ m_xhalf(m, k, err)

 }

 #endif

+#ifdef __linux__

+#include <linux/if_packet.h>

+#include <linux/filter.h>

+#endif

+

+enum {

+        BPF_S_ANC_NONE,

+        BPF_S_ANC_VLAN_TAG,

+        BPF_S_ANC_VLAN_TAG_PRESENT,

+};

+

 /*

  * Execute the filter program starting at pc on the packet p

  * wirelen is the length of the original packet

@@ -208,11 +219,12 @@ m_xhalf(m, k, err)

  * in all other cases, p is a pointer to a buffer and buflen is its size.

  */

 u_int

-bpf_filter(pc, p, wirelen, buflen)

+bpf_filter1(pc, p, wirelen, buflen, aux_data)

 	register const struct bpf_insn *pc;

 	register const u_char *p;

 	u_int wirelen;

 	register u_int buflen;

+        register const struct bpf_aux_data *aux_data;

 {

 	register u_int32 A, X;

 	register int k;

@@ -288,22 +300,50 @@ bpf_filter(pc, p, wirelen, buflen)

 			continue;

 		case BPF_LD|BPF_B|BPF_ABS:

-			k = pc->k;

-			if (k >= buflen) {

+			{

+#if defined(SKF_AD_VLAN_TAG) && defined(SKF_AD_VLAN_TAG_PRESENT)

+				int code = BPF_S_ANC_NONE;

+#define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE:		\

+				code = BPF_S_ANC_##CODE;		\

+                                        if (!aux_data)                  \

+                                                return 0;               \

+                                        break;

+

+				switch (pc->k) {

+					ANCILLARY(VLAN_TAG);

+					ANCILLARY(VLAN_TAG_PRESENT);

+				default :

+#endif

+					k = pc->k;

+					if (k >= buflen) {

 #if defined(KERNEL) || defined(_KERNEL)

-				if (m == NULL)

-					return 0;

-				n = m;

-				MINDEX(len, n, k);

-				A = mtod(n, u_char *)[k];

-				continue;

+						if (m == NULL)

+							return 0;

+						n = m;

+						MINDEX(len, n, k);

+						A = mtod(n, u_char *)[k];

+						continue;

 #else

-				return 0;

+						return 0;

+#endif

+					}

+					A = p[k];

+#if defined(SKF_AD_VLAN_TAG) && defined(SKF_AD_VLAN_TAG_PRESENT)

+				}

+				switch (code) {

+				case BPF_S_ANC_VLAN_TAG:

+					if (aux_data)

+						A = aux_data->vlan_tag;

+					break;

+

+				case BPF_S_ANC_VLAN_TAG_PRESENT:

+					if (aux_data)

+						A = aux_data->vlan_tag_present;

+					break;

+				}

 #endif

+				continue;

 			}

-			A = p[k];

-			continue;

-

 		case BPF_LD|BPF_W|BPF_LEN:

 			A = wirelen;

 			continue;

@@ -532,6 +572,17 @@ bpf_filter(pc, p, wirelen, buflen)

 	}

 }

+u_int

+bpf_filter(pc, p, wirelen, buflen)

+	register const struct bpf_insn *pc;

+	register const u_char *p;

+	u_int wirelen;

+	register u_int buflen;

+{

+	return bpf_filter1(pc, p, wirelen, buflen, NULL);

+}

+

+

 /*

  * Return true if the 'fcode' is a valid filter program.

  * The constraints are that each jump be forward and to a valid

diff --git a/pcap/bpf.h b/pcap/bpf.h

index 8286ed5..495f326 100644

--- a/pcap/bpf.h

+++ b/pcap/bpf.h

@@ -70,6 +70,9 @@

  *

  * This also provides our own multiple-include protection.

  */

+

+#include <stdint.h>

+

 #if !defined(_NET_BPF_H_) && !defined(_BPF_H_) && !defined(_H_BPF) && !defined(lib_pcap_bpf_h)

 #define lib_pcap_bpf_h

@@ -1317,6 +1320,11 @@ struct bpf_insn {

 	bpf_u_int32 k;

 };

+struct bpf_aux_data {

+        uint16_t vlan_tag_present;

+        uint16_t vlan_tag;

+};

+

 /*

  * Macros for insn array initializers.

  */

@@ -1326,9 +1334,11 @@ struct bpf_insn {

 #if __STDC__ || defined(__cplusplus)

 extern int bpf_validate(const struct bpf_insn *, int);

 extern u_int bpf_filter(const struct bpf_insn *, const u_char *, u_int, u_int);

+extern u_int bpf_filter1(const struct bpf_insn *, const u_char *, u_int, u_int, const struct bpf_aux_data *);        

 #else

 extern int bpf_validate();

 extern u_int bpf_filter();

+extern u_int bpf_filter();

 #endif

 /*

-- 

2.4.3