41. IPsec Security Gateway Sample Application

41.1. Overview

The application demonstrates the implementation of a Security Gateway (not IPsec compliant, see the Constraints section below) using DPDK based on RFC4301, RFC4303, RFC3602 and RFC2404.

Internet Key Exchange (IKE) is not implemented, so only manual setting of Security Policies and Security Associations is supported.

The Security Policies (SP) are implemented as ACL rules, the Security Associations (SA) are stored in a table and the routing is implemented using LPM.

The application classifies the ports as Protected and Unprotected. Thus, traffic received on an Unprotected or Protected port is consider Inbound or Outbound respectively.

The Path for IPsec Inbound traffic is:

• Read packets from the port.
• Classify packets between IPv4 and ESP.
• Perform Inbound SA lookup for ESP packets based on their SPI.
• Perform Verification/Decryption.
• Remove ESP and outer IP header
• Inbound SP check using ACL of decrypted packets and any other IPv4 packets.
• Routing.
• Write packet to port.

The Path for the IPsec Outbound traffic is:

• Read packets from the port.
• Perform Outbound SP check using ACL of all IPv4 traffic.
• Perform Outbound SA lookup for packets that need IPsec protection.
• Add ESP and outer IP header.
• Perform Encryption/Digest.
• Routing.
• Write packet to port.

41.2. Constraints

• No IPv6 options headers.
• No AH mode.
• Currently only EAS-CBC, HMAC-SHA1 and NULL.
• Each SA must be handle by a unique lcore (1 RX queue per port).
• No chained mbufs.

41.3. Compiling the Application

To compile the application:

1. Go to the sample application directory:

   export RTE_SDK=/path/to/rte_sdk
   cd ${RTE_SDK}/examples/ipsec-secgw
   

2. Set the target (a default target is used if not specified). For example:

   export RTE_TARGET=x86_64-native-linuxapp-gcc
   

   See the DPDK Getting Started Guide for possible RTE_TARGET values.

3. Build the application:

   make
   

4. [Optional] Build the application for debugging: This option adds some extra flags, disables compiler optimizations and is verbose:

   make DEBUG=1
   

41.4. Running the Application

The application has a number of command line options:

./build/ipsec-secgw [EAL options] --
                     -p PORTMASK -P -u PORTMASK
                     --config (port,queue,lcore)[,(port,queue,lcore]
                     --single-sa SAIDX
                     --ep0|--ep1

Where:

• -p PORTMASK: Hexadecimal bitmask of ports to configure.
• -P: optional. Sets all ports to promiscuous mode so that packets are accepted regardless of the packet’s Ethernet MAC destination address. Without this option, only packets with the Ethernet MAC destination address set to the Ethernet address of the port are accepted (default is enabled).
• -u PORTMASK: hexadecimal bitmask of unprotected ports
• --config (port,queue,lcore)[,(port,queue,lcore)]: determines which queues from which ports are mapped to which cores.
• --single-sa SAIDX: use a single SA for outbound traffic, bypassing the SP on both Inbound and Outbound. This option is meant for debugging/performance purposes.
• --ep0: configure the app as Endpoint 0.
• --ep1: configure the app as Endpoint 1.

Either one of --ep0 or --ep1 must be specified. The main purpose of these options is to easily configure two systems back-to-back that would forward traffic through an IPsec tunnel (see IPSec Inbound/Outbound traffic).

The mapping of lcores to port/queues is similar to other l3fwd applications.

For example, given the following command line:

./build/ipsec-secgw -l 20,21 -n 4 --socket-mem 0,2048       \
       --vdev "cryptodev_null_pmd" -- -p 0xf -P -u 0x3      \
       --config="(0,0,20),(1,0,20),(2,0,21),(3,0,21)" --ep0 \

where each options means:

• The -l option enables cores 20 and 21.

• The -n option sets memory 4 channels.

• The --socket-mem to use 2GB on socket 1.

• The --vdev "cryptodev_null_pmd" option creates virtual NULL cryptodev PMD.

• The -p option enables ports (detected) 0, 1, 2 and 3.

• The -P option enables promiscuous mode.

• The -u option sets ports 1 and 2 as unprotected, leaving 2 and 3 as protected.

• The --config option enables one queue per port with the following mapping:

  Port	Queue	lcore	Description
  0	0	20	Map queue 0 from port 0 to lcore 20.
  1	0	20	Map queue 0 from port 1 to lcore 20.
  2	0	21	Map queue 0 from port 2 to lcore 21.
  3	0	21	Map queue 0 from port 3 to lcore 21.

• The --ep0 options configures the app with a given set of SP, SA and Routing entries as explained below in more detail.

Refer to the DPDK Getting Started Guide for general information on running applications and the Environment Abstraction Layer (EAL) options.

The application would do a best effort to “map” crypto devices to cores, with hardware devices having priority. Basically, hardware devices if present would be assigned to a core before software ones. This means that if the application is using a single core and both hardware and software crypto devices are detected, hardware devices will be used.

A way to achieve the case where you want to force the use of virtual crypto devices is to whitelist the Ethernet devices needed and therefore implicitly blacklisting all hardware crypto devices.

For example, something like the following command line:

./build/ipsec-secgw -l 20,21 -n 4 --socket-mem 0,2048 \
        -w 81:00.0 -w 81:00.1 -w 81:00.2 -w 81:00.3 \
        --vdev "cryptodev_aesni_mb_pmd" --vdev "cryptodev_null_pmd" \
        -- \
        -p 0xf -P -u 0x3 --config="(0,0,20),(1,0,20),(2,0,21),(3,0,21)" \
        --ep0

41.5. Configurations

The following sections provide some details on the default values used to initialize the SP, SA and Routing tables. Currently all configuration information is hard coded into the application.

The following image illustrate a few of the concepts regarding IPSec, such as protected/unprotected and inbound/outbound traffic, from the point of view of two back-to-back endpoints:

Fig. 41.1 IPSec Inbound/Outbound traffic

Note that the above image only displays unidirectional traffic per port for illustration purposes. The application supports bidirectional traffic on all ports,