aboutsummaryrefslogtreecommitdiff
path: root/pcap-netfilter-linux.c
diff options
context:
space:
mode:
Diffstat (limited to 'pcap-netfilter-linux.c')
-rw-r--r--pcap-netfilter-linux.c265
1 files changed, 221 insertions, 44 deletions
diff --git a/pcap-netfilter-linux.c b/pcap-netfilter-linux.c
index f9c6beff6e82..48f29b025294 100644
--- a/pcap-netfilter-linux.c
+++ b/pcap-netfilter-linux.c
@@ -51,17 +51,33 @@
#include <linux/types.h>
#include <linux/netlink.h>
+#include <linux/netfilter.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_log.h>
+#include <linux/netfilter/nfnetlink_queue.h>
+/* NOTE: if your program drops privilages after pcap_activate() it WON'T work with nfqueue.
+ * It took me quite some time to debug ;/
+ *
+ * Sending any data to nfnetlink socket requires CAP_NET_ADMIN privilages,
+ * and in nfqueue we need to send verdict reply after recving packet.
+ *
+ * In tcpdump you can disable dropping privilages with -Z root
+ */
+
#include "pcap-netfilter-linux.h"
#define HDR_LENGTH (NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg))))
#define NFLOG_IFACE "nflog"
+#define NFQUEUE_IFACE "nfqueue"
+
+typedef enum { OTHER = -1, NFLOG, NFQUEUE } nftype_t;
+
+static int nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict);
static int
-nflog_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
+netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
{
const unsigned char *buf;
int count = 0;
@@ -85,6 +101,7 @@ nflog_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char
while (len >= NLMSG_SPACE(0)) {
const struct nlmsghdr *nlh = (const struct nlmsghdr *) buf;
u_int32_t msg_len;
+ nftype_t type = OTHER;
if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || len < nlh->nlmsg_len) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len);
@@ -93,10 +110,19 @@ nflog_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char
if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG &&
NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET)
- {
+ type = NFLOG;
+
+ if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE &&
+ NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET)
+ type = NFQUEUE;
+
+ if (type != OTHER) {
const unsigned char *payload = NULL;
struct pcap_pkthdr pkth;
+ const struct nfgenmsg *nfg;
+ int id = 0;
+
if (handle->linktype != DLT_NFLOG) {
const struct nfattr *payload_attr = NULL;
@@ -105,15 +131,32 @@ nflog_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char
return -1;
}
+ nfg = NLMSG_DATA(nlh);
if (nlh->nlmsg_len > HDR_LENGTH) {
- struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
+ struct nfattr *attr = NFM_NFA(nfg);
int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH);
while (NFA_OK(attr, attr_len)) {
- switch (NFA_TYPE(attr)) {
- case NFULA_PAYLOAD:
- payload_attr = attr;
- break;
+ if (type == NFQUEUE) {
+ switch (NFA_TYPE(attr)) {
+ case NFQA_PACKET_HDR:
+ {
+ const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr);
+
+ id = ntohl(pkt_hdr->packet_id);
+ break;
+ }
+ case NFQA_PAYLOAD:
+ payload_attr = attr;
+ break;
+ }
+
+ } else if (type == NFLOG) {
+ switch (NFA_TYPE(attr)) {
+ case NFULA_PAYLOAD:
+ payload_attr = attr;
+ break;
+ }
}
attr = NFA_NEXT(attr, attr_len);
}
@@ -141,6 +184,11 @@ nflog_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char
count++;
}
}
+
+ if (type == NFQUEUE) {
+ /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */
+ nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT);
+ }
}
msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
@@ -183,7 +231,7 @@ struct my_nfattr {
};
static int
-nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t res_id, const struct my_nfattr *mynfa)
+netfilter_send_config_msg(const pcap_t *handle, u_int16_t msg_type, int ack, u_int8_t family, u_int16_t res_id, const struct my_nfattr *mynfa)
{
char buf[1024] __attribute__ ((aligned));
@@ -198,8 +246,8 @@ nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t res_id, c
++seq_id;
nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg));
- nlh->nlmsg_type = (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG;
- nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+ nlh->nlmsg_type = msg_type;
+ nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0);
nlh->nlmsg_pid = 0; /* to kernel */
nlh->nlmsg_seq = seq_id;
@@ -222,6 +270,9 @@ nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t res_id, c
if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1)
return -1;
+ if (!ack)
+ return 0;
+
/* waiting for reply loop */
do {
socklen_t addrlen = sizeof(snl);
@@ -261,6 +312,12 @@ nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t res_id, c
}
static int
+nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
+{
+ return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa);
+}
+
+static int
nflog_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int8_t family)
{
struct nfulnl_msg_config_cmd msg;
@@ -292,20 +349,79 @@ nflog_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_m
}
static int
-nflog_activate(pcap_t* handle)
+nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict)
+{
+ struct nfqnl_msg_verdict_hdr msg;
+ struct my_nfattr nfa;
+
+ msg.id = htonl(id);
+ msg.verdict = htonl(verdict);
+
+ nfa.data = &msg;
+ nfa.nfa_type = NFQA_VERDICT_HDR;
+ nfa.nfa_len = sizeof(msg);
+
+ return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa);
+}
+
+static int
+nfqueue_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa)
+{
+ return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa);
+}
+
+static int
+nfqueue_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int16_t pf)
+{
+ struct nfqnl_msg_config_cmd msg;
+ struct my_nfattr nfa;
+
+ msg.command = cmd;
+ msg.pf = htons(pf);
+
+ nfa.data = &msg;
+ nfa.nfa_type = NFQA_CFG_CMD;
+ nfa.nfa_len = sizeof(msg);
+
+ return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
+}
+
+static int
+nfqueue_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range)
+{
+ struct nfqnl_msg_config_params msg;
+ struct my_nfattr nfa;
+
+ msg.copy_range = htonl(copy_range);
+ msg.copy_mode = copy_mode;
+
+ nfa.data = &msg;
+ nfa.nfa_type = NFQA_CFG_PARAMS;
+ nfa.nfa_len = sizeof(msg);
+
+ return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa);
+}
+
+static int
+netfilter_activate(pcap_t* handle)
{
const char *dev = handle->opt.source;
unsigned short groups[32];
int group_count = 0;
+ nftype_t type = OTHER;
int i;
- if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
- dev += strlen(NFLOG_IFACE);
-
- /* nflog:30,33,42 looks nice, allow it */
- if (*dev == ':')
- dev++;
+ if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
+ dev += strlen(NFLOG_IFACE);
+ type = NFLOG;
+ } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
+ dev += strlen(NFQUEUE_IFACE);
+ type = NFQUEUE;
+ }
+
+ if (type != OTHER && *dev == ':') {
+ dev++;
while (*dev) {
long int group_id;
char *end_dev;
@@ -335,7 +451,7 @@ nflog_activate(pcap_t* handle)
}
}
- if (*dev) {
+ if (type == OTHER || *dev) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Can't get netfilter group(s) index from %s",
handle->opt.source);
@@ -351,8 +467,7 @@ nflog_activate(pcap_t* handle)
/* Initialize some components of the pcap structure. */
handle->bufsize = 128 + handle->snapshot;
handle->offset = 0;
- handle->linktype = DLT_NFLOG;
- handle->read_op = nflog_read_linux;
+ handle->read_op = netfilter_read_linux;
handle->inject_op = netfilter_inject_linux;
handle->setfilter_op = install_bpf_program; /* no kernel filtering */
handle->setdirection_op = NULL;
@@ -369,12 +484,17 @@ nflog_activate(pcap_t* handle)
return PCAP_ERROR;
}
- handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
- if (handle->dlt_list != NULL) {
- handle->dlt_list[0] = DLT_NFLOG;
- handle->dlt_list[1] = DLT_IPV4;
- handle->dlt_count = 2;
- }
+ if (type == NFLOG) {
+ handle->linktype = DLT_NFLOG;
+ handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
+ if (handle->dlt_list != NULL) {
+ handle->dlt_list[0] = DLT_NFLOG;
+ handle->dlt_list[1] = DLT_IPV4;
+ handle->dlt_count = 2;
+ }
+
+ } else
+ handle->linktype = DLT_IPV4;
handle->buffer = malloc(handle->bufsize);
if (!handle->buffer) {
@@ -382,27 +502,53 @@ nflog_activate(pcap_t* handle)
goto close_fail;
}
- if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
- snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno));
- goto close_fail;
- }
+ if (type == NFLOG) {
+ if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
+ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno));
+ goto close_fail;
+ }
- if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
- snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno));
- goto close_fail;
- }
+ if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
+ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno));
+ goto close_fail;
+ }
+
+ /* Bind socket to the nflog groups */
+ for (i = 0; i < group_count; i++) {
+ if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
+ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno));
+ goto close_fail;
+ }
- /* Bind socket to the nflog groups */
- for (i = 0; i < group_count; i++) {
- if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
- snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno));
+ if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
+ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_COPY_PACKET: %s", pcap_strerror(errno));
+ goto close_fail;
+ }
+ }
+
+ } else {
+ if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
+ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno));
goto close_fail;
}
- if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
- snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_COPY_PACKET: %s", pcap_strerror(errno));
+ if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) {
+ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno));
goto close_fail;
}
+
+ /* Bind socket to the nfqueue groups */
+ for (i = 0; i < group_count; i++) {
+ if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
+ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno));
+ goto close_fail;
+ }
+
+ if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
+ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_COPY_PACKET: %s", pcap_strerror(errno));
+ goto close_fail;
+ }
+ }
}
if (handle->opt.rfmon) {
@@ -432,20 +578,50 @@ close_fail:
}
pcap_t *
-nflog_create(const char *device, char *ebuf)
+netfilter_create(const char *device, char *ebuf, int *is_ours)
{
+ const char *cp;
pcap_t *p;
+ /* Does this look like an netfilter device? */
+ cp = strrchr(device, '/');
+ if (cp == NULL)
+ cp = device;
+
+ /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */
+ if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0)
+ cp += sizeof NFLOG_IFACE - 1;
+ else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0)
+ cp += sizeof NFQUEUE_IFACE - 1;
+ else {
+ /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */
+ *is_ours = 0;
+ return NULL;
+ }
+
+ /*
+ * Yes - is that either the end of the name, or is it followed
+ * by a colon?
+ */
+ if (*cp != ':' && *cp != '\0') {
+ /* Nope */
+ *is_ours = 0;
+ return NULL;
+ }
+
+ /* OK, it's probably ours. */
+ *is_ours = 1;
+
p = pcap_create_common(device, ebuf);
if (p == NULL)
return (NULL);
- p->activate_op = nflog_activate;
+ p->activate_op = netfilter_activate;
return (p);
}
int
-netfilter_platform_finddevs(pcap_if_t **alldevsp, char *err_str)
+netfilter_findalldevs(pcap_if_t **alldevsp, char *err_str)
{
pcap_if_t *found_dev = *alldevsp;
int sock;
@@ -463,6 +639,7 @@ netfilter_platform_finddevs(pcap_if_t **alldevsp, char *err_str)
if (pcap_add_if(&found_dev, NFLOG_IFACE, 0, "Linux netfilter log (NFLOG) interface", err_str) < 0)
return -1;
+ if (pcap_add_if(&found_dev, NFQUEUE_IFACE, 0, "Linux netfilter queue (NFQUEUE) interface", err_str) < 0)
+ return -1;
return 0;
}
-
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-31 12:28:30 +0000