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wireshark/plugins/epan/falco_bridge/packet-falco-bridge.c

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/* packet-falco-bridge.c
*
* By Loris Degioanni
* Copyright (C) 2021 Sysdig, Inc.
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
// To do:
// - Convert this to C++? It would let us get rid of the glue that is
// sinsp-span and make string handling a lot easier. However,
// epan/address.h and driver/ppm_events_public.h both define PT_NONE.
// - Add a configuration preference for configure_plugin?
#include "config.h"
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#ifndef _WIN32
#include <unistd.h>
#include <dlfcn.h>
#endif
#include <epan/exceptions.h>
#include <epan/packet.h>
#include <epan/proto.h>
#include <epan/proto_data.h>
#include <epan/conversation_filter.h>
#include <epan/tap.h>
#include <epan/stat_tap_ui.h>
#include <wsutil/file_util.h>
#include <wsutil/filesystem.h>
#include "sinsp-span.h"
#include "conversation-macros.h"
typedef enum bridge_field_flags_e {
BFF_NONE = 0,
BFF_HIDDEN = 1 << 1, // Unused
BFF_INFO = 1 << 2,
BFF_CONVERSATION = 1 << 3
} bridge_field_flags_e;
typedef struct bridge_info {
sinsp_source_info_t *ssi;
uint32_t source_id;
int proto;
hf_register_info* hf;
int* hf_ids;
uint32_t visible_fields;
uint32_t* field_flags;
int* field_ids;
} bridge_info;
typedef struct conv_fld_info {
const char* proto_name;
hf_register_info* field_info;
char field_val[4096];
} conv_fld_info;
static int proto_falco_bridge = -1;
static gint ett_falco_bridge = -1;
static gint ett_sinsp_span = -1;
static dissector_table_t ptype_dissector_table;
static int dissect_falco_bridge(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data);
static int dissect_sinsp_span(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_);
void register_conversation_filters_mappings(void);
/*
* Array of plugin bridges
*/
bridge_info* bridges = NULL;
guint nbridges = 0;
guint n_conv_fields = 0;
/*
* sinsp extractor span
*/
sinsp_span_t *sinsp_span = NULL;
/*
* Fields
*/
static int hf_sdp_source_id_size = -1;
static int hf_sdp_lengths = -1;
static int hf_sdp_source_id = -1;
static hf_register_info hf[] = {
{ &hf_sdp_source_id_size,
{ "Plugin ID size", "falcobridge.id.size",
FT_UINT32, BASE_DEC,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_sdp_lengths,
{ "Field Lengths", "falcobridge.lens",
FT_UINT32, BASE_DEC,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_sdp_source_id,
{ "Plugin ID", "falcobridge.id",
FT_UINT32, BASE_DEC,
NULL, 0x0,
NULL, HFILL }
},
};
/*
* Conversation filters mappers setup
*/
#define MAX_CONV_FILTER_STR_LEN 1024
static conv_fld_info conv_fld_infos[MAX_N_CONV_FILTERS];
DECLARE_CONV_FLTS()
static char conv_flt_vals[MAX_N_CONV_FILTERS][MAX_CONV_FILTER_STR_LEN];
static guint conv_vals_cnt = 0;
void
register_conversation_filters_mappings(void)
{
MAP_CONV_FLTS()
}
void
configure_plugin(bridge_info* bi, char* config _U_)
{
/*
* Initialize the plugin
*/
bi->source_id = get_sinsp_source_id(bi->ssi);
uint32_t tot_fields = get_sinsp_source_nfields(bi->ssi);
bi->visible_fields = 0;
sinsp_field_info_t sfi;
for (uint32_t j = 0; j < tot_fields; j++) {
get_sinsp_source_field_info(bi->ssi, j, &sfi);
if (sfi.is_hidden) {
/*
* Skip the fields that are marked as hidden.
* XXX Should we keep them and call proto_item_set_hidden?
*/
continue;
}
bi->visible_fields++;
}
if (bi->visible_fields) {
bi->hf = (hf_register_info*)wmem_alloc(wmem_epan_scope(), bi->visible_fields * sizeof(hf_register_info));
bi->hf_ids = (int*)wmem_alloc(wmem_epan_scope(), bi->visible_fields * sizeof(int));
bi->field_ids = (int*)wmem_alloc(wmem_epan_scope(), bi->visible_fields * sizeof(int));
bi->field_flags = (guint32*)wmem_alloc(wmem_epan_scope(), bi->visible_fields * sizeof(guint32));
uint32_t fld_cnt = 0;
size_t conv_fld_cnt = 0;
for (uint32_t j = 0; j < tot_fields; j++)
{
bi->hf_ids[fld_cnt] = -1;
bi->field_ids[fld_cnt] = j;
bi->field_flags[fld_cnt] = BFF_NONE;
hf_register_info* ri = bi->hf + fld_cnt;
get_sinsp_source_field_info(bi->ssi, j, &sfi);
if (sfi.is_hidden) {
/*
* Skip the fields that are marked as hidden
*/
continue;
}
enum ftenum ftype;
int fdisplay = BASE_NONE;
switch (sfi.type) {
case SFT_STRINGZ:
ftype = FT_STRINGZ;
break;
case SFT_UINT64:
ftype = FT_UINT64;
switch (sfi.display_format) {
case SFDF_DECIMAL:
fdisplay = BASE_DEC;
break;
case SFDF_HEXADECIMAL:
fdisplay = BASE_HEX;
break;
case SFDF_OCTAL:
fdisplay = BASE_OCT;
break;
default:
THROW_FORMATTED(DissectorError, "error in plugin %s: display format %s is not supported",
get_sinsp_source_name(bi->ssi),
sfi.abbrev);
}
break;
default:
THROW_FORMATTED(DissectorError, "error in plugin %s: type of field %s is not supported",
get_sinsp_source_name(bi->ssi),
sfi.abbrev);
}
hf_register_info finfo = {
bi->hf_ids + fld_cnt,
{
wmem_strdup(wmem_epan_scope(), sfi.display), wmem_strdup(wmem_epan_scope(), sfi.abbrev),
ftype, fdisplay,
NULL, 0x0,
wmem_strdup(wmem_epan_scope(), sfi.description), HFILL
}
};
*ri = finfo;
if (sfi.is_info) {
bi->field_flags[fld_cnt] |= BFF_INFO;
}
if (sfi.is_conversation) {
bi->field_flags[fld_cnt] |= BFF_CONVERSATION;
conv_fld_infos[conv_fld_cnt].field_info = ri;
const char *source_name = get_sinsp_source_name(bi->ssi);
conv_fld_infos[conv_fld_cnt].proto_name = source_name;
// XXX We currently build a filter per field. Should we "and" them instead?
register_log_conversation_filter(source_name, finfo.hfinfo.name, fv_func[conv_fld_cnt], bfs_func[conv_fld_cnt]);
conv_fld_cnt++;
}
fld_cnt++;
}
proto_register_field_array(proto_falco_bridge, bi->hf, fld_cnt);
if (conv_fld_cnt > 0) {
add_conversation_filter_protocol(get_sinsp_source_name(bi->ssi));
}
}
}
void
import_plugin(char* fname)
{
nbridges++;
bridge_info* bi = &bridges[nbridges - 1];
sinsp_span = create_sinsp_span();
if (create_sinsp_source(sinsp_span, fname, &(bi->ssi)) == FALSE) {
nbridges--;
THROW_FORMATTED(DissectorError, "unable to load sinsp plugin %s.", fname);
}
configure_plugin(bi, "");
const char *source_name = get_sinsp_source_name(bi->ssi);
const char *plugin_name = g_strdup_printf("%s Plugin", source_name);
bi->proto = proto_register_protocol (
plugin_name, /* full name */
source_name, /* short name */
source_name /* filter_name */
);
static dissector_handle_t ct_handle;
ct_handle = create_dissector_handle(dissect_sinsp_span, bi->proto);
dissector_add_uint("falcobridge.id", bi->source_id, ct_handle);
}
static void
on_wireshark_exit(void)
{
destroy_sinsp_span(sinsp_span);
sinsp_span = NULL;
}
void
proto_register_falcoplugin(void)
{
proto_falco_bridge = proto_register_protocol (
"Falco Bridge", /* name */
"Falco Bridge", /* short name */
"falcobridge" /* abbrev */
);
register_dissector("falcobridge", dissect_falco_bridge, proto_falco_bridge);
/*
* Create the dissector table that we will use to route the dissection to
* the appropriate Falco plugin.
*/
ptype_dissector_table = register_dissector_table("falcobridge.id",
"Falco Bridge Plugin ID", proto_falco_bridge, FT_UINT32, BASE_DEC);
/*
* Create the mapping infrastructure for conversation filtering
*/
register_conversation_filters_mappings();
/*
* Load the plugins
*/
WS_DIR *dir;
WS_DIRENT *file;
char *filename;
char *dname = g_build_filename(get_plugins_dir_with_version(), "falco", NULL);
/*
* We scan the plugins directory twice. The first time we count how many
* plugins we have, which we need to know in order to allocate the right
* amount of memory. The second time we actually load and configure
* each plugin.
*/
if ((dir = ws_dir_open(dname, 0, NULL)) != NULL) {
while ((ws_dir_read_name(dir)) != NULL) {
nbridges++;
}
ws_dir_close(dir);
}
bridges = g_new(bridge_info, nbridges);
nbridges = 0;
if ((dir = ws_dir_open(dname, 0, NULL)) != NULL) {
while ((file = ws_dir_read_name(dir)) != NULL) {
filename = g_build_filename(dname, ws_dir_get_name(file), NULL);
import_plugin(filename);
g_free(filename);
}
ws_dir_close(dir);
}
g_free(dname);
/*
* Setup protocol subtree array
*/
static gint *ett[] = {
&ett_falco_bridge,
&ett_sinsp_span,
};
proto_register_field_array(proto_falco_bridge, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
register_shutdown_routine(on_wireshark_exit);
}
static bridge_info*
get_bridge_info(guint32 source_id)
{
for(guint j = 0; j < nbridges; j++)
{
if(bridges[j].source_id == source_id)
{
return &bridges[j];
}
}
return NULL;
}
#define PROTO_DATA_BRIDGE_HANDLE 0x00
static int
dissect_falco_bridge(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
conv_vals_cnt = 0;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "Falco Bridge");
/* Clear out stuff in the info column */
col_clear(pinfo->cinfo,COL_INFO);
// https://github.com/falcosecurity/libs/blob/9c942f27/userspace/libscap/scap.c#L1900
proto_item *ti = proto_tree_add_item(tree, proto_falco_bridge, tvb, 0, 12, ENC_NA);
proto_tree *fb_tree = proto_item_add_subtree(ti, ett_falco_bridge);
proto_tree_add_item(fb_tree, hf_sdp_source_id_size, tvb, 0, 4, ENC_LITTLE_ENDIAN);
proto_tree_add_item(fb_tree, hf_sdp_lengths, tvb, 4, 4, ENC_LITTLE_ENDIAN);
proto_item *idti = proto_tree_add_item(fb_tree, hf_sdp_source_id, tvb, 8, 4, ENC_LITTLE_ENDIAN);
guint32 source_id = tvb_get_guint32(tvb, 8, ENC_LITTLE_ENDIAN);
bridge_info* bi = get_bridge_info(source_id);
col_add_fstr(pinfo->cinfo, COL_INFO, "Plugin ID: %u", source_id);
if (bi == NULL) {
proto_item_append_text(idti, " (NOT SUPPORTED)");
col_append_str(pinfo->cinfo, COL_INFO, " (NOT SUPPORTED)");
return tvb_captured_length(tvb);
}
const char *source_name = get_sinsp_source_name(bi->ssi);
proto_item_append_text(idti, " (%s)", source_name);
col_append_fstr(pinfo->cinfo, COL_INFO, " (%s)", source_name);
dissector_handle_t dissector = dissector_get_uint_handle(ptype_dissector_table, source_id);
if (dissector) {
p_add_proto_data(pinfo->pool, pinfo, proto_falco_bridge, PROTO_DATA_BRIDGE_HANDLE, bi);
tvbuff_t* next_tvb = tvb_new_subset_length(tvb, 12, tvb_captured_length(tvb) - 12);
call_dissector_with_data(dissector, next_tvb, pinfo, tree, data);
}
return tvb_captured_length(tvb);
}
static int
dissect_sinsp_span(tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* data _U_)
{
bridge_info* bi = p_get_proto_data(pinfo->pool, pinfo, proto_falco_bridge, PROTO_DATA_BRIDGE_HANDLE);
guint plen = tvb_captured_length(tvb);
const char *source_name = get_sinsp_source_name(bi->ssi);
col_set_str(pinfo->cinfo, COL_PROTOCOL, source_name);
/* Clear out stuff in the info column */
col_clear(pinfo->cinfo, COL_INFO);
proto_item* ti = proto_tree_add_item(tree, bi->proto, tvb, 0, plen, ENC_NA);
proto_tree* fb_tree = proto_item_add_subtree(ti, ett_sinsp_span);
guint8* payload = (guint8*)tvb_get_ptr(tvb, 0, plen);
for (uint32_t fld_idx = 0; fld_idx < bi->visible_fields; fld_idx++) {
header_field_info* hfinfo = &(bi->hf[fld_idx].hfinfo);
sinsp_field_extract_t sfe;
sfe.field_id = bi->field_ids[fld_idx];
sfe.field_name = hfinfo->abbrev;
sfe.type = hfinfo->type == FT_STRINGZ ? SFT_STRINGZ : SFT_UINT64;
bool rc = extract_sisnp_source_field(bi->ssi, pinfo->num, payload, plen, pinfo->pool, &sfe);
if (!rc) {
REPORT_DISSECTOR_BUG("Falco plugin %s extract error", get_sinsp_source_name(bi->ssi));
}
if (!sfe.is_present) {
continue;
}
if (sfe.type == SFT_STRINGZ && hfinfo->type == FT_STRINGZ) {
proto_item *pi = proto_tree_add_string(fb_tree, bi->hf_ids[fld_idx], tvb, 0, plen, sfe.res_str);
if (bi->field_flags[fld_idx] & BFF_INFO) {
col_append_sep_fstr(pinfo->cinfo, COL_INFO, ", ", "%s", sfe.res_str);
// Mark it hidden, otherwise we end up with a bunch of empty "Info" tree items.
proto_item_set_hidden(pi);
}
if ((bi->field_flags[fld_idx] & BFF_CONVERSATION) != 0) {
char* cvalptr = conv_flt_vals[conv_vals_cnt];
snprintf(cvalptr, MAX_CONV_FILTER_STR_LEN, "%s", sfe.res_str);
p_add_proto_data(pinfo->pool,
pinfo,
proto_falco_bridge,
PROTO_DATA_CONVINFO_USER_BASE + conv_vals_cnt, cvalptr);
}
if ((bi->field_flags[fld_idx] & BFF_CONVERSATION) != 0) {
conv_vals_cnt++;
}
}
else if (sfe.type == SFT_UINT64 && hfinfo->type == FT_UINT64) {
proto_tree_add_uint64(fb_tree, bi->hf_ids[fld_idx], tvb, 0, plen, sfe.res_u64);
}
else {
REPORT_DISSECTOR_BUG("field %s has an unrecognized or mismatched type %u != %u",
hfinfo->abbrev, sfe.type, hfinfo->type);
}
}
return plen;
}
void
proto_reg_handoff_sdplugin(void)
{
}
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