packetbeat: Enable setting promiscuous mode automatically (elastic#11366

)

packetbeat: Enable setting promiscuous mode automatically  (elastic#11366)

CHANGELOG.next.asciidoc

@@ -84,6 +84,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 
 *Packetbeat*
 
+- Enable setting promiscuous mode automatically. {pull}11366[11366]
 
 *Winlogbeat*
 

packetbeat/Dockerfile

@@ -0,0 +1,15 @@
+FROM golang:1.13.7
+
+RUN \
+    apt-get update \
+      && apt-get install -y --no-install-recommends \
+         python-pip \
+         virtualenv \
+         librpm-dev \
+         netcat \
+         libpcap-dev \
+      && rm -rf /var/lib/apt/lists/*
+
+RUN pip install --upgrade pip
+RUN pip install --upgrade setuptools
+RUN pip install --upgrade docker-compose==1.23.2

packetbeat/Makefile

@@ -1,7 +1,7 @@
 BEAT_NAME?=packetbeat
 BEAT_TITLE?=Packetbeat
 SYSTEM_TESTS?=true
-TEST_ENVIRONMENT=false
+TEST_ENVIRONMENT?=true
 ES_BEATS?=..
 EXCLUDE_COMMON_UPDATE_TARGET=true
 

packetbeat/_meta/beat.reference.yml

@@ -40,6 +40,13 @@ packetbeat.interfaces.device: {{ call .device .GOOS }}
 # Use this setting to override the automatically generated BPF filter.
 #packetbeat.interfaces.bpf_filter:
 
+# With `auto_promisc_mode` Packetbeat puts interface in promiscuous mode automatically on startup.
+# This option does not work with `any` interface device.
+# The default option is false and requires manual set-up of promiscuous mode.
+# Warning: under some circumstances (e.g beat crash) promiscuous mode
+# can stay enabled even after beat is shut down.
+#packetbeat.interfaces.auto_promisc_mode: true
+
 #================================== Flows =====================================
 
 packetbeat.flows:

packetbeat/config/config.go

@@ -36,17 +36,18 @@ type Config struct {
 }
 
 type InterfacesConfig struct {
-	Device       string `config:"device"`
-	Type         string `config:"type"`
-	File         string `config:"file"`
-	WithVlans    bool   `config:"with_vlans"`
-	BpfFilter    string `config:"bpf_filter"`
-	Snaplen      int    `config:"snaplen"`
-	BufferSizeMb int    `config:"buffer_size_mb"`
-	TopSpeed     bool
-	Dumpfile     string
-	OneAtATime   bool
-	Loop         int
+	Device                string `config:"device"`
+	Type                  string `config:"type"`
+	File                  string `config:"file"`
+	WithVlans             bool   `config:"with_vlans"`
+	BpfFilter             string `config:"bpf_filter"`
+	Snaplen               int    `config:"snaplen"`
+	BufferSizeMb          int    `config:"buffer_size_mb"`
+	EnableAutoPromiscMode bool   `config:"auto_promisc_mode"`
+	TopSpeed              bool
+	Dumpfile              string
+	OneAtATime            bool
+	Loop                  int
 }
 
 type Flows struct {

packetbeat/docker-compose.yml

@@ -0,0 +1,37 @@
+version: '2.3'
+services:
+  beat:
+    build: ${PWD}/.
+    depends_on:
+      - proxy_dep
+    working_dir: /go/src/github.com/elastic/beats/packetbeat
+    environment:
+      - ES_HOST=elasticsearch
+      - ES_PORT=9200
+      - ES_USER=beats
+      - ES_PASS=testing
+      - KIBANA_HOST=kibana
+      - KIBANA_PORT=5601
+    volumes:
+      - ${PWD}/..:/go/src/github.com/elastic/beats/
+    command: make
+    privileged: true
+    pid: host
+
+  # This is a proxy used to block beats until all services are healthy.
+  # See: https://github.com/docker/compose/issues/4369
+  proxy_dep:
+    image: busybox
+    depends_on:
+      elasticsearch: { condition: service_healthy }
+      kibana: { condition: service_healthy }
+
+  elasticsearch:
+    extends:
+      file: ../testing/environments/${TESTING_ENVIRONMENT}.yml
+      service: elasticsearch
+
+  kibana:
+    extends:
+      file: ../testing/environments/${TESTING_ENVIRONMENT}.yml
+      service: kibana

packetbeat/docs/packetbeat-options.asciidoc

@@ -176,6 +176,26 @@ packetbeat.interfaces.type: af_packet
 packetbeat.interfaces.buffer_size_mb: 100
 ------------------------------------------------------------------------------
 
+[float]
+==== `auto_promisc_mode`
+
+With `auto_promisc_mode` Packetbeat puts interface in promiscuous mode automatically on startup.
+This option does not work with `any` interface device.
+The default option is false and requires manual set-up of promiscuous mode.
+Warning: under some circumstances (e.g beat crash) promiscuous mode
+can stay enabled even after beat is shut down.
+
+Example:
+
+[source,yaml]
+------------------------------------------------------------------------------
+packetbeat.interfaces.device: eth0
+packetbeat.interfaces.type: af_packet
+packetbeat.interfaces.buffer_size_mb: 100
+packetbeat.interfaces.auto_promisc_mode: true
+------------------------------------------------------------------------------
+
+
 [float]
 ==== `with_vlans`
 

packetbeat/packetbeat.reference.yml

@@ -40,6 +40,13 @@ packetbeat.interfaces.device: any
 # Use this setting to override the automatically generated BPF filter.
 #packetbeat.interfaces.bpf_filter:
 
+# With `auto_promisc_mode` Packetbeat puts interface in promiscuous mode automatically on startup.
+# This option does not work with `any` interface device.
+# The default option is false and requires manual set-up of promiscuous mode.
+# Warning: under some circumstances (e.g beat crash) promiscuous mode
+# can stay enabled even after beat is shut down.
+#packetbeat.interfaces.auto_promisc_mode: true
+
 #================================== Flows =====================================
 
 packetbeat.flows:

packetbeat/sniffer/afpacket_linux.go

@@ -20,22 +20,49 @@
 package sniffer
 
 import (
+	"fmt"
+	"syscall"
 	"time"
+	"unsafe"
+
+	"github.com/elastic/beats/libbeat/logp"
 
 	"github.com/tsg/gopacket"
 	"github.com/tsg/gopacket/afpacket"
 	"github.com/tsg/gopacket/layers"
 )
 
 type afpacketHandle struct {
-	TPacket *afpacket.TPacket
+	TPacket                      *afpacket.TPacket
+	promiscPreviousState         bool
+	promiscPreviousStateDetected bool
+	device                       string
 }
 
 func newAfpacketHandle(device string, snaplen int, block_size int, num_blocks int,
-	timeout time.Duration) (*afpacketHandle, error) {
+	timeout time.Duration, autoPromiscMode bool) (*afpacketHandle, error) {
 
-	h := &afpacketHandle{}
 	var err error
+	var promiscEnabled bool
+
+	if autoPromiscMode {
+		promiscEnabled, err = isPromiscEnabled(device)
+		if err != nil {
+			logp.Err("Failed to get promiscuous mode for device '%s': %v", device, err)
+		}
+
+		if !promiscEnabled {
+			if setPromiscErr := setPromiscMode(device, true); setPromiscErr != nil {
+				logp.Warn("Failed to set promiscuous mode for device '%s'. Packetbeat may be unable to see any network traffic. Please follow packetbeat FAQ to learn about mitigation: Error: %v", device, err)
+			}
+		}
+	}
+
+	h := &afpacketHandle{
+		promiscPreviousState:         promiscEnabled,
+		device:                       device,
+		promiscPreviousStateDetected: autoPromiscMode && err == nil,
+	}
 
 	if device == "any" {
 		h.TPacket, err = afpacket.NewTPacket(
@@ -69,4 +96,51 @@ func (h *afpacketHandle) LinkType() layers.LinkType {
 
 func (h *afpacketHandle) Close() {
 	h.TPacket.Close()
+	// previous state detected only if auto mode was on
+	if h.promiscPreviousStateDetected {
+		if err := setPromiscMode(h.device, h.promiscPreviousState); err != nil {
+			logp.Warn("Failed to reset promiscuous mode for device '%s'. Your device might be in promiscuous mode.: %v", h.device, err)
+		}
+	}
+}
+
+func isPromiscEnabled(device string) (bool, error) {
+	if device == "any" {
+		return false, nil
+	}
+
+	s, e := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, 0)
+	if e != nil {
+		return false, e
+	}
+
+	defer syscall.Close(s)
+
+	var ifreq struct {
+		name  [syscall.IFNAMSIZ]byte
+		flags uint16
+	}
+
+	copy(ifreq.name[:], []byte(device))
+	_, _, ep := syscall.Syscall(syscall.SYS_IOCTL, uintptr(s), syscall.SIOCGIFFLAGS, uintptr(unsafe.Pointer(&ifreq)))
+	if ep != 0 {
+		return false, fmt.Errorf("ioctl command SIOCGIFFLAGS failed to get device flags for %v: return code %d", device, ep)
+	}
+
+	return ifreq.flags&uint16(syscall.IFF_PROMISC) != 0, nil
+}
+
+// setPromiscMode enables promisc mode if configured.
+// this makes maintenance for user simpler without any additional manual steps
+// issue [700](https://github.com/elastic/beats/issues/700)
+func setPromiscMode(device string, enabled bool) error {
+	if device == "any" {
+		logp.Warn("Cannot set promiscuous mode to device 'any'")
+		return nil
+	}
+
+	// SetLsfPromisc is marked as deprecated but used to improve readability (bpf)
+	// and avoid Cgo (pcap)
+	// TODO: replace with x/net/bpf or pcap
+	return syscall.SetLsfPromisc(device, enabled)
 }

packetbeat/sniffer/afpacket_nonlinux.go

@@ -31,7 +31,7 @@ type afpacketHandle struct {
 }
 
 func newAfpacketHandle(device string, snaplen int, blockSize int, numBlocks int,
-	timeout time.Duration) (*afpacketHandle, error) {
+	timeout time.Duration, enableAutoPromiscMode bool) (*afpacketHandle, error) {
 
 	return nil, fmt.Errorf("Afpacket MMAP sniffing is only available on Linux")
 }

packetbeat/sniffer/sniffer.go

@@ -305,7 +305,7 @@ func openAFPacket(filter string, cfg *config.InterfacesConfig) (snifferHandle, e
 	}
 
 	timeout := 500 * time.Millisecond
-	h, err := newAfpacketHandle(cfg.Device, szFrame, szBlock, numBlocks, timeout)
+	h, err := newAfpacketHandle(cfg.Device, szFrame, szBlock, numBlocks, timeout, cfg.EnableAutoPromiscMode)
 	if err != nil {
 		return nil, err
 	}

packetbeat/tests/system/config/packetbeat.yml.j2

@@ -4,6 +4,12 @@
 # keyword to sniff on all connected interfaces.
 packetbeat.interfaces.device: {{ iface_device|default("any") }}
 
+{% if af_packet %}
+packetbeat.interfaces.type: af_packet
+packetbeat.interfaces.buffer_size_mb: 100
+packetbeat.interfaces.auto_promisc_mode: true
+{% endif %}
+
 {% if bpf_filter %}
 packetbeat.interfaces.bpf_filter: {{ bpf_filter }}
 {% endif %}

packetbeat/tests/system/test_0069_af_packet.py

@@ -0,0 +1,84 @@
+import os
+import subprocess
+import sys
+import time
+import unittest
+from packetbeat import BaseTest
+
+"""
+Tests for afpacket.
+"""
+
+
+def is_root():
+    if 'geteuid' not in dir(os):
+        return False
+    euid = os.geteuid()
+    print("euid is", euid)
+    return euid == 0
+
+
+class Test(BaseTest):
+
+    @unittest.skipUnless(
+        sys.platform.startswith("linux"),
+        "af_packet only on Linux")
+    @unittest.skipUnless(is_root(), "Requires root")
+    def test_afpacket_promisc(self):
+        """
+        Should switch to promisc mode and back.
+        """
+
+        # get device name, leave out loopback device
+        devices = [f for f in os.listdir(
+            "/sys/class/net") if f.startswith("lo")]
+        assert len(devices) > 0
+
+        device = devices[0]
+
+        ip_proc = subprocess.Popen(
+            ["ip", "link", "show", device], stdout=subprocess.PIPE)
+        o, e = ip_proc.communicate()
+        assert e is None
+
+        prev_promisc = "PROMISC" in o.decode("utf-8")
+
+        # turn off promics if was on
+        if prev_promisc:
+            subprocess.call(["ip", "link", "set", device,
+                             "promisc", "off"], stdout=subprocess.PIPE)
+
+        self.render_config_template(
+            af_packet=True,
+            iface_device=device
+        )
+        packetbeat = self.start_packetbeat()
+
+        # wait for promisc to be turned on, cap(90s)
+        for x in range(10):
+            time.sleep(5)
+
+            ip_proc = subprocess.Popen(
+                ["ip", "link", "show", device], stdout=subprocess.PIPE)
+            o, e = ip_proc.communicate()
+
+            is_promisc = "PROMISC" in o.decode("utf-8")
+            if is_promisc:
+                break
+
+        assert is_promisc
+
+        # stop packetbeat and check if promisc is set to previous state
+        packetbeat.kill_and_wait()
+
+        ip_proc = subprocess.Popen(
+            ["ip", "link", "show", device], stdout=subprocess.PIPE)
+        o, e = ip_proc.communicate()
+        assert e is None
+
+        is_promisc = "PROMISC" in o.decode("utf-8")
+        assert is_promisc == False
+
+        # reset device
+        if prev_promisc:
+            subprocess.call(["ip", "link", "set", device, "promisc", "on"])