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base/SOURCES/0002-Use-BPF-extensions-in-...

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From e80ed31b6e3ab778a7e0dd53348f488a91456cfc Mon Sep 17 00:00:00 2001
From: Michal Sekletar <msekleta@redhat.com>
Date: Fri, 31 Oct 2014 15:19:54 +0100
Subject: [PATCH 2/2] Use BPF extensions in compiled filters
libpcap will generate BPF filter code which uses BPF extensions if target
platform supports them. Currently supported BPF extensions are vlan_tci and
vlan_pr.
Also to properly handle such filters when filtering in userspace libpcap now
employs bpf_filter1.
(cherry picked from 04660eb1e56102e2369473cae2538e4d3d263607)
Conflicts:
pcap-linux.c
---
gencode.c | 110 +++++++++++++++++++++++++++++++++++++++++++++--------------
pcap-linux.c | 23 +++++++++----
2 files changed, 102 insertions(+), 31 deletions(-)
diff --git a/gencode.c b/gencode.c
index d58ea30..2ff725e 100644
--- a/gencode.c
+++ b/gencode.c
@@ -58,6 +58,7 @@ static const char rcsid[] _U_ =
#include <netinet/in.h>
#include <arpa/inet.h>
+#include <errno.h>
#endif /* WIN32 */
@@ -135,9 +136,9 @@ static pcap_t *bpf_pcap;
/* Hack for updating VLAN, MPLS, and PPPoE offsets. */
#ifdef WIN32
-static u_int orig_linktype = (u_int)-1, orig_nl = (u_int)-1, label_stack_depth = (u_int)-1;
+static u_int orig_linktype = (u_int)-1, orig_nl = (u_int)-1, label_stack_depth = (u_int)-1, vlan_stack_depth = (u_int)-1;
#else
-static u_int orig_linktype = -1U, orig_nl = -1U, label_stack_depth = -1U;
+static u_int orig_linktype = -1U, orig_nl = -1U, label_stack_depth = -1U, vlan_stack_depth = -1U;
#endif
/* XXX */
@@ -962,6 +963,7 @@ init_linktype(p)
orig_linktype = -1;
orig_nl = -1;
label_stack_depth = 0;
+ vlan_stack_depth = 0;
reg_off_ll = -1;
reg_off_macpl = -1;
@@ -7861,6 +7863,76 @@ gen_ahostop(eaddr, dir)
/* NOTREACHED */
}
+#if defined(SKF_AD_VLAN_TAG) && defined(SKF_AD_VLAN_TAG_PRESENT)
+static int skf_ad_vlan_tag_present_supported(int bpf_extensions) {
+ return bpf_extensions >= SKF_AD_VLAN_TAG_PRESENT;
+}
+
+static struct block *
+gen_vlan_bpf_extensions(int vlan_num) {
+ struct block *b0, *b1;
+ struct slist *s;
+ int val = 0, len, r;
+
+ len = sizeof(val);
+ r = getsockopt(bpf_pcap->fd, SOL_SOCKET, SO_BPF_EXTENSIONS, &val, &len);
+ if (r < 0)
+ return NULL;
+
+ if (!skf_ad_vlan_tag_present_supported(val))
+ return NULL;
+
+ /* generate new filter code based on extracting packet
+ * metadata */
+ s = new_stmt(BPF_LD|BPF_B|BPF_ABS);
+ s->s.k = SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT;
+
+ b0 = new_block(JMP(BPF_JEQ));
+ b0->stmts = s;
+ b0->s.k = 1;
+
+ if (vlan_num >= 0) {
+ s = new_stmt(BPF_LD|BPF_B|BPF_ABS);
+ s->s.k = SKF_AD_OFF + SKF_AD_VLAN_TAG;
+
+ b1 = new_block(JMP(BPF_JEQ));
+ b1->stmts = s;
+ b1->s.k = (bpf_int32) vlan_num;
+
+ gen_and(b0,b1);
+ b0 = b1;
+ }
+
+ return b0;
+}
+#endif
+
+static struct block *
+gen_vlan_no_bpf_extensions(int vlan_num) {
+ struct block *b0, *b1;
+
+ /* check for VLAN, including QinQ */
+ b0 = gen_cmp(OR_LINK, off_linktype, BPF_H,
+ (bpf_int32)ETHERTYPE_8021Q);
+ b1 = gen_cmp(OR_LINK, off_linktype, BPF_H,
+ (bpf_int32)ETHERTYPE_8021QINQ);
+ gen_or(b0,b1);
+ b0 = b1;
+
+ /* If a specific VLAN is requested, check VLAN id */
+ if (vlan_num >= 0) {
+ b1 = gen_mcmp(OR_MACPL, 0, BPF_H,
+ (bpf_int32)vlan_num, 0x0fff);
+ gen_and(b0, b1);
+ b0 = b1;
+ }
+
+ off_macpl += 4;
+ off_linktype += 4;
+
+ return b0;
+}
+
/*
* support IEEE 802.1Q VLAN trunk over ethernet
*/
@@ -7912,36 +7984,24 @@ gen_vlan(vlan_num)
case DLT_EN10MB:
case DLT_NETANALYZER:
case DLT_NETANALYZER_TRANSPARENT:
- /* check for VLAN, including QinQ */
- b0 = gen_cmp(OR_LINK, off_linktype, BPF_H,
- (bpf_int32)ETHERTYPE_8021Q);
- b1 = gen_cmp(OR_LINK, off_linktype, BPF_H,
- (bpf_int32)ETHERTYPE_8021QINQ);
- gen_or(b0,b1);
- b0 = b1;
-
- /* If a specific VLAN is requested, check VLAN id */
- if (vlan_num >= 0) {
- b1 = gen_mcmp(OR_MACPL, 0, BPF_H,
- (bpf_int32)vlan_num, 0x0fff);
- gen_and(b0, b1);
- b0 = b1;
- }
-
- off_macpl += 4;
- off_linktype += 4;
-#if 0
- off_nl_nosnap += 4;
- off_nl += 4;
+#if defined(SKF_AD_VLAN_TAG) && defined(SKF_AD_VLAN_TAG_PRESENT)
+ if (!vlan_stack_depth) {
+ b0 = gen_vlan_bpf_extensions(vlan_num);
+ if (!b0)
+ b0 = gen_vlan_no_bpf_extensions(vlan_num);
+ }
+ else
#endif
- break;
-
+ b0 = gen_vlan_no_bpf_extensions(vlan_num);
+ break;
default:
bpf_error("no VLAN support for data link type %d",
linktype);
/*NOTREACHED*/
}
+ vlan_stack_depth++;
+
return (b0);
}
diff --git a/pcap-linux.c b/pcap-linux.c
index a0e543c..68e6d05 100644
--- a/pcap-linux.c
+++ b/pcap-linux.c
@@ -1475,6 +1475,7 @@ pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
int packet_len, caplen;
struct pcap_pkthdr pcap_header;
+ struct bpf_aux_data aux_data;
#ifdef HAVE_PF_PACKET_SOCKETS
/*
* If this is a cooked device, leave extra room for a
@@ -1658,6 +1659,11 @@ pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
tag->vlan_tpid = htons(ETH_P_8021Q);
tag->vlan_tci = htons(aux->tp_vlan_tci);
+ /* store vlan tci to bpf_aux_data struct for userland bpf filter */
+#if defined(TP_STATUS_VLAN_VALID)
+ aux_data.vlan_tag = htons(aux->tp_vlan_tci) & 0x0fff;
+ aux_data.vlan_tag_present = (aux->tp_status & TP_STATUS_VLAN_VALID);
+#endif
packet_len += VLAN_TAG_LEN;
}
}
@@ -1702,8 +1708,8 @@ pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
/* Run the packet filter if not using kernel filter */
if (handlep->filter_in_userland && handle->fcode.bf_insns) {
- if (bpf_filter(handle->fcode.bf_insns, bp,
- packet_len, caplen) == 0)
+ if (bpf_filter1(handle->fcode.bf_insns, bp,
+ packet_len, caplen, &aux_data) == 0)
{
/* rejected by filter */
return 0;
@@ -4270,10 +4276,15 @@ static int pcap_handle_packet_mmap(
snaplen += sizeof(struct sll_header);
}
- if (handlep->filter_in_userland && handle->fcode.bf_insns &&
- (bpf_filter(handle->fcode.bf_insns, bp,
- tp_len, snaplen) == 0))
- return 0;
+ if (handlep->filter_in_userland && handle->fcode.bf_insns) {
+ struct bpf_aux_data aux_data;
+
+ aux_data.vlan_tag = tp_vlan_tci & 0x0fff;
+ aux_data.vlan_tag_present = tp_vlan_tci_valid;
+
+ if (bpf_filter1(handle->fcode.bf_insns, bp, tp_len, tp_snaplen, &aux_data) == 0)
+ return 0;
+ }
if (!linux_check_direction(handle, sll))
return 0;
--
2.4.3