2005-04-16 16:20:36 -06:00
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--------------------------------------------------------------------------------
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+ ABSTRACT
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--------------------------------------------------------------------------------
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2010-02-05 17:29:48 -07:00
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This file documents the mmap() facility available with the PACKET
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2012-11-07 19:37:01 -07:00
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socket interface on 2.4/2.6/3.x kernels. This type of sockets is used for
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i) capture network traffic with utilities like tcpdump, ii) transmit network
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traffic, or any other that needs raw access to network interface.
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2005-04-16 16:20:36 -06:00
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2009-05-18 23:11:22 -06:00
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You can find the latest version of this document at:
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2010-07-23 21:51:24 -06:00
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http://wiki.ipxwarzone.com/index.php5?title=Linux_packet_mmap
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2005-04-16 16:20:36 -06:00
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2009-05-18 23:11:22 -06:00
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Howto can be found at:
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http://wiki.gnu-log.net (packet_mmap)
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2005-04-16 16:20:36 -06:00
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2009-05-18 23:11:22 -06:00
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Please send your comments to
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2007-05-09 00:50:42 -06:00
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Ulisses Alonso Camaró <uaca@i.hate.spam.alumni.uv.es>
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2009-05-18 23:11:22 -06:00
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Johann Baudy <johann.baudy@gnu-log.net>
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2005-04-16 16:20:36 -06:00
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-------------------------------------------------------------------------------
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+ Why use PACKET_MMAP
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--------------------------------------------------------------------------------
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2012-11-07 19:37:01 -07:00
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In Linux 2.4/2.6/3.x if PACKET_MMAP is not enabled, the capture process is very
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inefficient. It uses very limited buffers and requires one system call to
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capture each packet, it requires two if you want to get packet's timestamp
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(like libpcap always does).
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2005-04-16 16:20:36 -06:00
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In the other hand PACKET_MMAP is very efficient. PACKET_MMAP provides a size
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2009-05-18 23:11:22 -06:00
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configurable circular buffer mapped in user space that can be used to either
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send or receive packets. This way reading packets just needs to wait for them,
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most of the time there is no need to issue a single system call. Concerning
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transmission, multiple packets can be sent through one system call to get the
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2012-11-07 19:37:01 -07:00
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highest bandwidth. By using a shared buffer between the kernel and the user
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also has the benefit of minimizing packet copies.
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2009-05-18 23:11:22 -06:00
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It's fine to use PACKET_MMAP to improve the performance of the capture and
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transmission process, but it isn't everything. At least, if you are capturing
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at high speeds (this is relative to the cpu speed), you should check if the
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device driver of your network interface card supports some sort of interrupt
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load mitigation or (even better) if it supports NAPI, also make sure it is
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enabled. For transmission, check the MTU (Maximum Transmission Unit) used and
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2012-11-07 19:37:01 -07:00
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supported by devices of your network. CPU IRQ pinning of your network interface
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card can also be an advantage.
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2005-04-16 16:20:36 -06:00
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--------------------------------------------------------------------------------
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2010-02-05 17:29:48 -07:00
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+ How to use mmap() to improve capture process
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2005-04-16 16:20:36 -06:00
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--------------------------------------------------------------------------------
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2006-03-24 10:23:14 -07:00
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From the user standpoint, you should use the higher level libpcap library, which
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2005-04-16 16:20:36 -06:00
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is a de facto standard, portable across nearly all operating systems
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including Win32.
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Said that, at time of this writing, official libpcap 0.8.1 is out and doesn't include
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support for PACKET_MMAP, and also probably the libpcap included in your distribution.
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I'm aware of two implementations of PACKET_MMAP in libpcap:
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2010-07-23 21:51:24 -06:00
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http://wiki.ipxwarzone.com/ (by Simon Patarin, based on libpcap 0.6.2)
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2005-04-16 16:20:36 -06:00
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http://public.lanl.gov/cpw/ (by Phil Wood, based on lastest libpcap)
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The rest of this document is intended for people who want to understand
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the low level details or want to improve libpcap by including PACKET_MMAP
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support.
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--------------------------------------------------------------------------------
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2010-02-05 17:29:48 -07:00
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+ How to use mmap() directly to improve capture process
|
2005-04-16 16:20:36 -06:00
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--------------------------------------------------------------------------------
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From the system calls stand point, the use of PACKET_MMAP involves
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the following process:
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[setup] socket() -------> creation of the capture socket
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setsockopt() ---> allocation of the circular buffer (ring)
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2009-05-18 23:11:22 -06:00
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option: PACKET_RX_RING
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2006-10-03 14:46:31 -06:00
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mmap() ---------> mapping of the allocated buffer to the
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2005-04-16 16:20:36 -06:00
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user process
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[capture] poll() ---------> to wait for incoming packets
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[shutdown] close() --------> destruction of the capture socket and
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deallocation of all associated
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resources.
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socket creation and destruction is straight forward, and is done
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the same way with or without PACKET_MMAP:
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2012-11-07 19:37:01 -07:00
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int fd = socket(PF_PACKET, mode, htons(ETH_P_ALL));
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2005-04-16 16:20:36 -06:00
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where mode is SOCK_RAW for the raw interface were link level
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information can be captured or SOCK_DGRAM for the cooked
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interface where link level information capture is not
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supported and a link level pseudo-header is provided
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by the kernel.
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The destruction of the socket and all associated resources
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is done by a simple call to close(fd).
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2014-01-10 02:22:37 -07:00
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Similarly as without PACKET_MMAP, it is possible to use one socket
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for capture and transmission. This can be done by mapping the
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allocated RX and TX buffer ring with a single mmap() call.
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See "Mapping and use of the circular buffer (ring)".
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2010-04-22 16:08:02 -06:00
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Next I will describe PACKET_MMAP settings and its constraints,
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2006-10-03 14:46:31 -06:00
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also the mapping of the circular buffer in the user process and
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2005-04-16 16:20:36 -06:00
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the use of this buffer.
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2009-05-18 23:11:22 -06:00
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--------------------------------------------------------------------------------
|
2010-02-05 17:29:48 -07:00
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+ How to use mmap() directly to improve transmission process
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2009-05-18 23:11:22 -06:00
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--------------------------------------------------------------------------------
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Transmission process is similar to capture as shown below.
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[setup] socket() -------> creation of the transmission socket
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setsockopt() ---> allocation of the circular buffer (ring)
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option: PACKET_TX_RING
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bind() ---------> bind transmission socket with a network interface
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mmap() ---------> mapping of the allocated buffer to the
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user process
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[transmission] poll() ---------> wait for free packets (optional)
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send() ---------> send all packets that are set as ready in
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the ring
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The flag MSG_DONTWAIT can be used to return
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before end of transfer.
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[shutdown] close() --------> destruction of the transmission socket and
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deallocation of all associated resources.
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|
2013-12-06 03:36:15 -07:00
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Socket creation and destruction is also straight forward, and is done
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the same way as in capturing described in the previous paragraph:
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int fd = socket(PF_PACKET, mode, 0);
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The protocol can optionally be 0 in case we only want to transmit
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via this socket, which avoids an expensive call to packet_rcv().
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In this case, you also need to bind(2) the TX_RING with sll_protocol = 0
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set. Otherwise, htons(ETH_P_ALL) or any other protocol, for example.
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|
2009-05-18 23:11:22 -06:00
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Binding the socket to your network interface is mandatory (with zero copy) to
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know the header size of frames used in the circular buffer.
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As capture, each frame contains two parts:
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--------------------
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| struct tpacket_hdr | Header. It contains the status of
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| | of this frame
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|--------------------|
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| data buffer |
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. . Data that will be sent over the network interface.
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. .
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--------------------
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bind() associates the socket to your network interface thanks to
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sll_ifindex parameter of struct sockaddr_ll.
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Initialization example:
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struct sockaddr_ll my_addr;
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struct ifreq s_ifr;
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...
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strncpy (s_ifr.ifr_name, "eth0", sizeof(s_ifr.ifr_name));
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/* get interface index of eth0 */
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ioctl(this->socket, SIOCGIFINDEX, &s_ifr);
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/* fill sockaddr_ll struct to prepare binding */
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my_addr.sll_family = AF_PACKET;
|
2011-12-22 10:47:54 -07:00
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my_addr.sll_protocol = htons(ETH_P_ALL);
|
2009-05-18 23:11:22 -06:00
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my_addr.sll_ifindex = s_ifr.ifr_ifindex;
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/* bind socket to eth0 */
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bind(this->socket, (struct sockaddr *)&my_addr, sizeof(struct sockaddr_ll));
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A complete tutorial is available at: http://wiki.gnu-log.net/
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|
2012-11-06 16:10:47 -07:00
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By default, the user should put data at :
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frame base + TPACKET_HDRLEN - sizeof(struct sockaddr_ll)
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So, whatever you choose for the socket mode (SOCK_DGRAM or SOCK_RAW),
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the beginning of the user data will be at :
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frame base + TPACKET_ALIGN(sizeof(struct tpacket_hdr))
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If you wish to put user data at a custom offset from the beginning of
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the frame (for payload alignment with SOCK_RAW mode for instance) you
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can set tp_net (with SOCK_DGRAM) or tp_mac (with SOCK_RAW). In order
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to make this work it must be enabled previously with setsockopt()
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and the PACKET_TX_HAS_OFF option.
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|
2005-04-16 16:20:36 -06:00
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--------------------------------------------------------------------------------
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+ PACKET_MMAP settings
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--------------------------------------------------------------------------------
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To setup PACKET_MMAP from user level code is done with a call like
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|
2009-05-18 23:11:22 -06:00
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- Capture process
|
2005-04-16 16:20:36 -06:00
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setsockopt(fd, SOL_PACKET, PACKET_RX_RING, (void *) &req, sizeof(req))
|
2009-05-18 23:11:22 -06:00
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- Transmission process
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setsockopt(fd, SOL_PACKET, PACKET_TX_RING, (void *) &req, sizeof(req))
|
2005-04-16 16:20:36 -06:00
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The most significant argument in the previous call is the req parameter,
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this parameter must to have the following structure:
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struct tpacket_req
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{
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unsigned int tp_block_size; /* Minimal size of contiguous block */
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unsigned int tp_block_nr; /* Number of blocks */
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unsigned int tp_frame_size; /* Size of frame */
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unsigned int tp_frame_nr; /* Total number of frames */
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};
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This structure is defined in /usr/include/linux/if_packet.h and establishes a
|
2009-05-18 23:11:22 -06:00
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circular buffer (ring) of unswappable memory.
|
2005-04-16 16:20:36 -06:00
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Being mapped in the capture process allows reading the captured frames and
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related meta-information like timestamps without requiring a system call.
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|
2009-05-18 23:11:22 -06:00
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Frames are grouped in blocks. Each block is a physically contiguous
|
2005-04-16 16:20:36 -06:00
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region of memory and holds tp_block_size/tp_frame_size frames. The total number
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of blocks is tp_block_nr. Note that tp_frame_nr is a redundant parameter because
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frames_per_block = tp_block_size/tp_frame_size
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indeed, packet_set_ring checks that the following condition is true
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frames_per_block * tp_block_nr == tp_frame_nr
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Lets see an example, with the following values:
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tp_block_size= 4096
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tp_frame_size= 2048
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tp_block_nr = 4
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tp_frame_nr = 8
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we will get the following buffer structure:
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block #1 block #2
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+---------+---------+ +---------+---------+
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| frame 1 | frame 2 | | frame 3 | frame 4 |
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+---------+---------+ +---------+---------+
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block #3 block #4
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+---------+---------+ +---------+---------+
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| frame 5 | frame 6 | | frame 7 | frame 8 |
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+---------+---------+ +---------+---------+
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|
A frame can be of any size with the only condition it can fit in a block. A block
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|
can only hold an integer number of frames, or in other words, a frame cannot
|
2011-03-30 19:57:33 -06:00
|
|
|
be spawned across two blocks, so there are some details you have to take into
|
2006-10-03 14:46:31 -06:00
|
|
|
account when choosing the frame_size. See "Mapping and use of the circular
|
2005-04-16 16:20:36 -06:00
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|
|
buffer (ring)".
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|
|
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|
|
--------------------------------------------------------------------------------
|
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|
+ PACKET_MMAP setting constraints
|
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|
--------------------------------------------------------------------------------
|
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|
|
In kernel versions prior to 2.4.26 (for the 2.4 branch) and 2.6.5 (2.6 branch),
|
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|
|
the PACKET_MMAP buffer could hold only 32768 frames in a 32 bit architecture or
|
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|
16384 in a 64 bit architecture. For information on these kernel versions
|
|
|
|
see http://pusa.uv.es/~ulisses/packet_mmap/packet_mmap.pre-2.4.26_2.6.5.txt
|
|
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|
|
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|
|
Block size limit
|
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|
|
------------------
|
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|
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|
|
As stated earlier, each block is a contiguous physical region of memory. These
|
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|
memory regions are allocated with calls to the __get_free_pages() function. As
|
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|
the name indicates, this function allocates pages of memory, and the second
|
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|
|
argument is "order" or a power of two number of pages, that is
|
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|
|
(for PAGE_SIZE == 4096) order=0 ==> 4096 bytes, order=1 ==> 8192 bytes,
|
|
|
|
order=2 ==> 16384 bytes, etc. The maximum size of a
|
|
|
|
region allocated by __get_free_pages is determined by the MAX_ORDER macro. More
|
|
|
|
precisely the limit can be calculated as:
|
|
|
|
|
|
|
|
PAGE_SIZE << MAX_ORDER
|
|
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|
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|
|
In a i386 architecture PAGE_SIZE is 4096 bytes
|
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|
In a 2.4/i386 kernel MAX_ORDER is 10
|
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|
In a 2.6/i386 kernel MAX_ORDER is 11
|
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|
So get_free_pages can allocate as much as 4MB or 8MB in a 2.4/2.6 kernel
|
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|
|
respectively, with an i386 architecture.
|
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|
|
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|
|
User space programs can include /usr/include/sys/user.h and
|
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|
|
/usr/include/linux/mmzone.h to get PAGE_SIZE MAX_ORDER declarations.
|
|
|
|
|
|
|
|
The pagesize can also be determined dynamically with the getpagesize (2)
|
|
|
|
system call.
|
|
|
|
|
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|
|
Block number limit
|
|
|
|
--------------------
|
|
|
|
|
|
|
|
To understand the constraints of PACKET_MMAP, we have to see the structure
|
|
|
|
used to hold the pointers to each block.
|
|
|
|
|
|
|
|
Currently, this structure is a dynamically allocated vector with kmalloc
|
|
|
|
called pg_vec, its size limits the number of blocks that can be allocated.
|
|
|
|
|
|
|
|
+---+---+---+---+
|
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|
|
| x | x | x | x |
|
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|
|
+---+---+---+---+
|
|
|
|
| | | |
|
|
|
|
| | | v
|
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|
|
| | v block #4
|
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|
| v block #3
|
|
|
|
v block #2
|
|
|
|
block #1
|
|
|
|
|
2006-10-03 14:50:39 -06:00
|
|
|
kmalloc allocates any number of bytes of physically contiguous memory from
|
|
|
|
a pool of pre-determined sizes. This pool of memory is maintained by the slab
|
2006-03-24 10:23:14 -07:00
|
|
|
allocator which is at the end the responsible for doing the allocation and
|
|
|
|
hence which imposes the maximum memory that kmalloc can allocate.
|
2005-04-16 16:20:36 -06:00
|
|
|
|
|
|
|
In a 2.4/2.6 kernel and the i386 architecture, the limit is 131072 bytes. The
|
|
|
|
predetermined sizes that kmalloc uses can be checked in the "size-<bytes>"
|
|
|
|
entries of /proc/slabinfo
|
|
|
|
|
|
|
|
In a 32 bit architecture, pointers are 4 bytes long, so the total number of
|
|
|
|
pointers to blocks is
|
|
|
|
|
|
|
|
131072/4 = 32768 blocks
|
|
|
|
|
|
|
|
PACKET_MMAP buffer size calculator
|
|
|
|
------------------------------------
|
|
|
|
|
|
|
|
Definitions:
|
|
|
|
|
|
|
|
<size-max> : is the maximum size of allocable with kmalloc (see /proc/slabinfo)
|
|
|
|
<pointer size>: depends on the architecture -- sizeof(void *)
|
|
|
|
<page size> : depends on the architecture -- PAGE_SIZE or getpagesize (2)
|
|
|
|
<max-order> : is the value defined with MAX_ORDER
|
|
|
|
<frame size> : it's an upper bound of frame's capture size (more on this later)
|
|
|
|
|
|
|
|
from these definitions we will derive
|
|
|
|
|
|
|
|
<block number> = <size-max>/<pointer size>
|
|
|
|
<block size> = <pagesize> << <max-order>
|
|
|
|
|
|
|
|
so, the max buffer size is
|
|
|
|
|
|
|
|
<block number> * <block size>
|
|
|
|
|
|
|
|
and, the number of frames be
|
|
|
|
|
|
|
|
<block number> * <block size> / <frame size>
|
|
|
|
|
2006-03-31 16:29:43 -07:00
|
|
|
Suppose the following parameters, which apply for 2.6 kernel and an
|
2005-04-16 16:20:36 -06:00
|
|
|
i386 architecture:
|
|
|
|
|
|
|
|
<size-max> = 131072 bytes
|
|
|
|
<pointer size> = 4 bytes
|
|
|
|
<pagesize> = 4096 bytes
|
|
|
|
<max-order> = 11
|
|
|
|
|
2006-10-03 14:46:31 -06:00
|
|
|
and a value for <frame size> of 2048 bytes. These parameters will yield
|
2005-04-16 16:20:36 -06:00
|
|
|
|
|
|
|
<block number> = 131072/4 = 32768 blocks
|
|
|
|
<block size> = 4096 << 11 = 8 MiB.
|
|
|
|
|
|
|
|
and hence the buffer will have a 262144 MiB size. So it can hold
|
|
|
|
262144 MiB / 2048 bytes = 134217728 frames
|
|
|
|
|
|
|
|
Actually, this buffer size is not possible with an i386 architecture.
|
|
|
|
Remember that the memory is allocated in kernel space, in the case of
|
|
|
|
an i386 kernel's memory size is limited to 1GiB.
|
|
|
|
|
|
|
|
All memory allocations are not freed until the socket is closed. The memory
|
|
|
|
allocations are done with GFP_KERNEL priority, this basically means that
|
|
|
|
the allocation can wait and swap other process' memory in order to allocate
|
2006-10-03 14:52:05 -06:00
|
|
|
the necessary memory, so normally limits can be reached.
|
2005-04-16 16:20:36 -06:00
|
|
|
|
|
|
|
Other constraints
|
|
|
|
-------------------
|
|
|
|
|
|
|
|
If you check the source code you will see that what I draw here as a frame
|
2006-11-29 21:21:10 -07:00
|
|
|
is not only the link level frame. At the beginning of each frame there is a
|
2005-04-16 16:20:36 -06:00
|
|
|
header called struct tpacket_hdr used in PACKET_MMAP to hold link level's frame
|
|
|
|
meta information like timestamp. So what we draw here a frame it's really
|
|
|
|
the following (from include/linux/if_packet.h):
|
|
|
|
|
|
|
|
/*
|
|
|
|
Frame structure:
|
|
|
|
|
|
|
|
- Start. Frame must be aligned to TPACKET_ALIGNMENT=16
|
|
|
|
- struct tpacket_hdr
|
|
|
|
- pad to TPACKET_ALIGNMENT=16
|
|
|
|
- struct sockaddr_ll
|
2006-10-03 14:45:33 -06:00
|
|
|
- Gap, chosen so that packet data (Start+tp_net) aligns to
|
2005-04-16 16:20:36 -06:00
|
|
|
TPACKET_ALIGNMENT=16
|
|
|
|
- Start+tp_mac: [ Optional MAC header ]
|
|
|
|
- Start+tp_net: Packet data, aligned to TPACKET_ALIGNMENT=16.
|
|
|
|
- Pad to align to TPACKET_ALIGNMENT=16
|
|
|
|
*/
|
|
|
|
|
|
|
|
The following are conditions that are checked in packet_set_ring
|
|
|
|
|
|
|
|
tp_block_size must be a multiple of PAGE_SIZE (1)
|
|
|
|
tp_frame_size must be greater than TPACKET_HDRLEN (obvious)
|
|
|
|
tp_frame_size must be a multiple of TPACKET_ALIGNMENT
|
|
|
|
tp_frame_nr must be exactly frames_per_block*tp_block_nr
|
|
|
|
|
2006-10-03 14:46:31 -06:00
|
|
|
Note that tp_block_size should be chosen to be a power of two or there will
|
2005-04-16 16:20:36 -06:00
|
|
|
be a waste of memory.
|
|
|
|
|
|
|
|
--------------------------------------------------------------------------------
|
2006-10-03 14:46:31 -06:00
|
|
|
+ Mapping and use of the circular buffer (ring)
|
2005-04-16 16:20:36 -06:00
|
|
|
--------------------------------------------------------------------------------
|
|
|
|
|
2006-10-03 14:46:31 -06:00
|
|
|
The mapping of the buffer in the user process is done with the conventional
|
2005-04-16 16:20:36 -06:00
|
|
|
mmap function. Even the circular buffer is compound of several physically
|
|
|
|
discontiguous blocks of memory, they are contiguous to the user space, hence
|
|
|
|
just one call to mmap is needed:
|
|
|
|
|
|
|
|
mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
|
|
|
|
|
|
|
|
If tp_frame_size is a divisor of tp_block_size frames will be
|
2008-07-25 20:45:33 -06:00
|
|
|
contiguously spaced by tp_frame_size bytes. If not, each
|
2005-04-16 16:20:36 -06:00
|
|
|
tp_block_size/tp_frame_size frames there will be a gap between
|
|
|
|
the frames. This is because a frame cannot be spawn across two
|
|
|
|
blocks.
|
|
|
|
|
2014-01-10 02:22:37 -07:00
|
|
|
To use one socket for capture and transmission, the mapping of both the
|
|
|
|
RX and TX buffer ring has to be done with one call to mmap:
|
|
|
|
|
|
|
|
...
|
|
|
|
setsockopt(fd, SOL_PACKET, PACKET_RX_RING, &foo, sizeof(foo));
|
|
|
|
setsockopt(fd, SOL_PACKET, PACKET_TX_RING, &bar, sizeof(bar));
|
|
|
|
...
|
|
|
|
rx_ring = mmap(0, size * 2, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
|
|
|
|
tx_ring = rx_ring + size;
|
|
|
|
|
|
|
|
RX must be the first as the kernel maps the TX ring memory right
|
|
|
|
after the RX one.
|
|
|
|
|
2005-04-16 16:20:36 -06:00
|
|
|
At the beginning of each frame there is an status field (see
|
|
|
|
struct tpacket_hdr). If this field is 0 means that the frame is ready
|
|
|
|
to be used for the kernel, If not, there is a frame the user can read
|
|
|
|
and the following flags apply:
|
|
|
|
|
2009-05-18 23:11:22 -06:00
|
|
|
+++ Capture process:
|
2005-04-16 16:20:36 -06:00
|
|
|
from include/linux/if_packet.h
|
|
|
|
|
|
|
|
#define TP_STATUS_COPY 2
|
|
|
|
#define TP_STATUS_LOSING 4
|
|
|
|
#define TP_STATUS_CSUMNOTREADY 8
|
|
|
|
|
|
|
|
TP_STATUS_COPY : This flag indicates that the frame (and associated
|
|
|
|
meta information) has been truncated because it's
|
|
|
|
larger than tp_frame_size. This packet can be
|
|
|
|
read entirely with recvfrom().
|
|
|
|
|
|
|
|
In order to make this work it must to be
|
|
|
|
enabled previously with setsockopt() and
|
|
|
|
the PACKET_COPY_THRESH option.
|
|
|
|
|
|
|
|
The number of frames than can be buffered to
|
|
|
|
be read with recvfrom is limited like a normal socket.
|
|
|
|
See the SO_RCVBUF option in the socket (7) man page.
|
|
|
|
|
|
|
|
TP_STATUS_LOSING : indicates there were packet drops from last time
|
|
|
|
statistics where checked with getsockopt() and
|
|
|
|
the PACKET_STATISTICS option.
|
|
|
|
|
2006-03-24 10:23:14 -07:00
|
|
|
TP_STATUS_CSUMNOTREADY: currently it's used for outgoing IP packets which
|
2010-04-22 16:08:02 -06:00
|
|
|
its checksum will be done in hardware. So while
|
2005-04-16 16:20:36 -06:00
|
|
|
reading the packet we should not try to check the
|
|
|
|
checksum.
|
|
|
|
|
|
|
|
for convenience there are also the following defines:
|
|
|
|
|
|
|
|
#define TP_STATUS_KERNEL 0
|
|
|
|
#define TP_STATUS_USER 1
|
|
|
|
|
|
|
|
The kernel initializes all frames to TP_STATUS_KERNEL, when the kernel
|
|
|
|
receives a packet it puts in the buffer and updates the status with
|
|
|
|
at least the TP_STATUS_USER flag. Then the user can read the packet,
|
|
|
|
once the packet is read the user must zero the status field, so the kernel
|
|
|
|
can use again that frame buffer.
|
|
|
|
|
|
|
|
The user can use poll (any other variant should apply too) to check if new
|
|
|
|
packets are in the ring:
|
|
|
|
|
|
|
|
struct pollfd pfd;
|
|
|
|
|
|
|
|
pfd.fd = fd;
|
|
|
|
pfd.revents = 0;
|
|
|
|
pfd.events = POLLIN|POLLRDNORM|POLLERR;
|
|
|
|
|
|
|
|
if (status == TP_STATUS_KERNEL)
|
|
|
|
retval = poll(&pfd, 1, timeout);
|
|
|
|
|
|
|
|
It doesn't incur in a race condition to first check the status value and
|
|
|
|
then poll for frames.
|
|
|
|
|
2009-05-18 23:11:22 -06:00
|
|
|
++ Transmission process
|
|
|
|
Those defines are also used for transmission:
|
|
|
|
|
|
|
|
#define TP_STATUS_AVAILABLE 0 // Frame is available
|
|
|
|
#define TP_STATUS_SEND_REQUEST 1 // Frame will be sent on next send()
|
|
|
|
#define TP_STATUS_SENDING 2 // Frame is currently in transmission
|
|
|
|
#define TP_STATUS_WRONG_FORMAT 4 // Frame format is not correct
|
|
|
|
|
|
|
|
First, the kernel initializes all frames to TP_STATUS_AVAILABLE. To send a
|
|
|
|
packet, the user fills a data buffer of an available frame, sets tp_len to
|
|
|
|
current data buffer size and sets its status field to TP_STATUS_SEND_REQUEST.
|
|
|
|
This can be done on multiple frames. Once the user is ready to transmit, it
|
|
|
|
calls send(). Then all buffers with status equal to TP_STATUS_SEND_REQUEST are
|
|
|
|
forwarded to the network device. The kernel updates each status of sent
|
|
|
|
frames with TP_STATUS_SENDING until the end of transfer.
|
|
|
|
At the end of each transfer, buffer status returns to TP_STATUS_AVAILABLE.
|
|
|
|
|
|
|
|
header->tp_len = in_i_size;
|
|
|
|
header->tp_status = TP_STATUS_SEND_REQUEST;
|
|
|
|
retval = send(this->socket, NULL, 0, 0);
|
|
|
|
|
|
|
|
The user can also use poll() to check if a buffer is available:
|
|
|
|
(status == TP_STATUS_SENDING)
|
|
|
|
|
|
|
|
struct pollfd pfd;
|
|
|
|
pfd.fd = fd;
|
|
|
|
pfd.revents = 0;
|
|
|
|
pfd.events = POLLOUT;
|
|
|
|
retval = poll(&pfd, 1, timeout);
|
|
|
|
|
2012-11-07 19:37:01 -07:00
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
+ What TPACKET versions are available and when to use them?
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
int val = tpacket_version;
|
|
|
|
setsockopt(fd, SOL_PACKET, PACKET_VERSION, &val, sizeof(val));
|
|
|
|
getsockopt(fd, SOL_PACKET, PACKET_VERSION, &val, sizeof(val));
|
|
|
|
|
|
|
|
where 'tpacket_version' can be TPACKET_V1 (default), TPACKET_V2, TPACKET_V3.
|
|
|
|
|
|
|
|
TPACKET_V1:
|
|
|
|
- Default if not otherwise specified by setsockopt(2)
|
|
|
|
- RX_RING, TX_RING available
|
|
|
|
|
|
|
|
TPACKET_V1 --> TPACKET_V2:
|
|
|
|
- Made 64 bit clean due to unsigned long usage in TPACKET_V1
|
|
|
|
structures, thus this also works on 64 bit kernel with 32 bit
|
|
|
|
userspace and the like
|
|
|
|
- Timestamp resolution in nanoseconds instead of microseconds
|
|
|
|
- RX_RING, TX_RING available
|
2013-12-20 07:12:20 -07:00
|
|
|
- VLAN metadata information available for packets
|
|
|
|
(TP_STATUS_VLAN_VALID, TP_STATUS_VLAN_TPID_VALID),
|
|
|
|
in the tpacket2_hdr structure:
|
|
|
|
- TP_STATUS_VLAN_VALID bit being set into the tp_status field indicates
|
|
|
|
that the tp_vlan_tci field has valid VLAN TCI value
|
|
|
|
- TP_STATUS_VLAN_TPID_VALID bit being set into the tp_status field
|
|
|
|
indicates that the tp_vlan_tpid field has valid VLAN TPID value
|
2012-11-07 19:37:01 -07:00
|
|
|
- How to switch to TPACKET_V2:
|
|
|
|
1. Replace struct tpacket_hdr by struct tpacket2_hdr
|
|
|
|
2. Query header len and save
|
|
|
|
3. Set protocol version to 2, set up ring as usual
|
|
|
|
4. For getting the sockaddr_ll,
|
|
|
|
use (void *)hdr + TPACKET_ALIGN(hdrlen) instead of
|
|
|
|
(void *)hdr + TPACKET_ALIGN(sizeof(struct tpacket_hdr))
|
|
|
|
|
|
|
|
TPACKET_V2 --> TPACKET_V3:
|
|
|
|
- Flexible buffer implementation:
|
|
|
|
1. Blocks can be configured with non-static frame-size
|
|
|
|
2. Read/poll is at a block-level (as opposed to packet-level)
|
|
|
|
3. Added poll timeout to avoid indefinite user-space wait
|
|
|
|
on idle links
|
|
|
|
4. Added user-configurable knobs:
|
|
|
|
4.1 block::timeout
|
|
|
|
4.2 tpkt_hdr::sk_rxhash
|
|
|
|
- RX Hash data available in user space
|
|
|
|
- Currently only RX_RING available
|
|
|
|
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
+ AF_PACKET fanout mode
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
In the AF_PACKET fanout mode, packet reception can be load balanced among
|
|
|
|
processes. This also works in combination with mmap(2) on packet sockets.
|
|
|
|
|
2013-08-28 14:13:11 -06:00
|
|
|
Currently implemented fanout policies are:
|
|
|
|
|
|
|
|
- PACKET_FANOUT_HASH: schedule to socket by skb's rxhash
|
|
|
|
- PACKET_FANOUT_LB: schedule to socket by round-robin
|
|
|
|
- PACKET_FANOUT_CPU: schedule to socket by CPU packet arrives on
|
|
|
|
- PACKET_FANOUT_RND: schedule to socket by random selection
|
|
|
|
- PACKET_FANOUT_ROLLOVER: if one socket is full, rollover to another
|
2014-01-27 09:43:04 -07:00
|
|
|
- PACKET_FANOUT_QM: schedule to socket by skbs recorded queue_mapping
|
2013-08-28 14:13:11 -06:00
|
|
|
|
2012-11-07 19:37:01 -07:00
|
|
|
Minimal example code by David S. Miller (try things like "./test eth0 hash",
|
|
|
|
"./test eth0 lb", etc.):
|
|
|
|
|
|
|
|
#include <stddef.h>
|
|
|
|
#include <stdlib.h>
|
|
|
|
#include <stdio.h>
|
|
|
|
#include <string.h>
|
|
|
|
|
|
|
|
#include <sys/types.h>
|
|
|
|
#include <sys/wait.h>
|
|
|
|
#include <sys/socket.h>
|
|
|
|
#include <sys/ioctl.h>
|
|
|
|
|
|
|
|
#include <unistd.h>
|
|
|
|
|
|
|
|
#include <linux/if_ether.h>
|
|
|
|
#include <linux/if_packet.h>
|
|
|
|
|
|
|
|
#include <net/if.h>
|
|
|
|
|
|
|
|
static const char *device_name;
|
|
|
|
static int fanout_type;
|
|
|
|
static int fanout_id;
|
|
|
|
|
|
|
|
#ifndef PACKET_FANOUT
|
|
|
|
# define PACKET_FANOUT 18
|
|
|
|
# define PACKET_FANOUT_HASH 0
|
|
|
|
# define PACKET_FANOUT_LB 1
|
|
|
|
#endif
|
|
|
|
|
|
|
|
static int setup_socket(void)
|
|
|
|
{
|
|
|
|
int err, fd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_IP));
|
|
|
|
struct sockaddr_ll ll;
|
|
|
|
struct ifreq ifr;
|
|
|
|
int fanout_arg;
|
|
|
|
|
|
|
|
if (fd < 0) {
|
|
|
|
perror("socket");
|
|
|
|
return EXIT_FAILURE;
|
|
|
|
}
|
|
|
|
|
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
|
|
strcpy(ifr.ifr_name, device_name);
|
|
|
|
err = ioctl(fd, SIOCGIFINDEX, &ifr);
|
|
|
|
if (err < 0) {
|
|
|
|
perror("SIOCGIFINDEX");
|
|
|
|
return EXIT_FAILURE;
|
|
|
|
}
|
|
|
|
|
|
|
|
memset(&ll, 0, sizeof(ll));
|
|
|
|
ll.sll_family = AF_PACKET;
|
|
|
|
ll.sll_ifindex = ifr.ifr_ifindex;
|
|
|
|
err = bind(fd, (struct sockaddr *) &ll, sizeof(ll));
|
|
|
|
if (err < 0) {
|
|
|
|
perror("bind");
|
|
|
|
return EXIT_FAILURE;
|
|
|
|
}
|
|
|
|
|
|
|
|
fanout_arg = (fanout_id | (fanout_type << 16));
|
|
|
|
err = setsockopt(fd, SOL_PACKET, PACKET_FANOUT,
|
|
|
|
&fanout_arg, sizeof(fanout_arg));
|
|
|
|
if (err) {
|
|
|
|
perror("setsockopt");
|
|
|
|
return EXIT_FAILURE;
|
|
|
|
}
|
|
|
|
|
|
|
|
return fd;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void fanout_thread(void)
|
|
|
|
{
|
|
|
|
int fd = setup_socket();
|
|
|
|
int limit = 10000;
|
|
|
|
|
|
|
|
if (fd < 0)
|
|
|
|
exit(fd);
|
|
|
|
|
|
|
|
while (limit-- > 0) {
|
|
|
|
char buf[1600];
|
|
|
|
int err;
|
|
|
|
|
|
|
|
err = read(fd, buf, sizeof(buf));
|
|
|
|
if (err < 0) {
|
|
|
|
perror("read");
|
|
|
|
exit(EXIT_FAILURE);
|
|
|
|
}
|
|
|
|
if ((limit % 10) == 0)
|
|
|
|
fprintf(stdout, "(%d) \n", getpid());
|
|
|
|
}
|
|
|
|
|
|
|
|
fprintf(stdout, "%d: Received 10000 packets\n", getpid());
|
|
|
|
|
|
|
|
close(fd);
|
|
|
|
exit(0);
|
|
|
|
}
|
|
|
|
|
|
|
|
int main(int argc, char **argp)
|
|
|
|
{
|
|
|
|
int fd, err;
|
|
|
|
int i;
|
|
|
|
|
|
|
|
if (argc != 3) {
|
|
|
|
fprintf(stderr, "Usage: %s INTERFACE {hash|lb}\n", argp[0]);
|
|
|
|
return EXIT_FAILURE;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!strcmp(argp[2], "hash"))
|
|
|
|
fanout_type = PACKET_FANOUT_HASH;
|
|
|
|
else if (!strcmp(argp[2], "lb"))
|
|
|
|
fanout_type = PACKET_FANOUT_LB;
|
|
|
|
else {
|
|
|
|
fprintf(stderr, "Unknown fanout type [%s]\n", argp[2]);
|
|
|
|
exit(EXIT_FAILURE);
|
|
|
|
}
|
|
|
|
|
|
|
|
device_name = argp[1];
|
|
|
|
fanout_id = getpid() & 0xffff;
|
|
|
|
|
|
|
|
for (i = 0; i < 4; i++) {
|
|
|
|
pid_t pid = fork();
|
|
|
|
|
|
|
|
switch (pid) {
|
|
|
|
case 0:
|
|
|
|
fanout_thread();
|
|
|
|
|
|
|
|
case -1:
|
|
|
|
perror("fork");
|
|
|
|
exit(EXIT_FAILURE);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
for (i = 0; i < 4; i++) {
|
|
|
|
int status;
|
|
|
|
|
|
|
|
wait(&status);
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2013-03-28 23:36:29 -06:00
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
+ AF_PACKET TPACKET_V3 example
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
AF_PACKET's TPACKET_V3 ring buffer can be configured to use non-static frame
|
|
|
|
sizes by doing it's own memory management. It is based on blocks where polling
|
|
|
|
works on a per block basis instead of per ring as in TPACKET_V2 and predecessor.
|
|
|
|
|
|
|
|
It is said that TPACKET_V3 brings the following benefits:
|
|
|
|
*) ~15 - 20% reduction in CPU-usage
|
|
|
|
*) ~20% increase in packet capture rate
|
|
|
|
*) ~2x increase in packet density
|
|
|
|
*) Port aggregation analysis
|
|
|
|
*) Non static frame size to capture entire packet payload
|
|
|
|
|
|
|
|
So it seems to be a good candidate to be used with packet fanout.
|
|
|
|
|
|
|
|
Minimal example code by Daniel Borkmann based on Chetan Loke's lolpcap (compile
|
|
|
|
it with gcc -Wall -O2 blob.c, and try things like "./a.out eth0", etc.):
|
|
|
|
|
2013-06-06 08:08:13 -06:00
|
|
|
/* Written from scratch, but kernel-to-user space API usage
|
|
|
|
* dissected from lolpcap:
|
|
|
|
* Copyright 2011, Chetan Loke <loke.chetan@gmail.com>
|
|
|
|
* License: GPL, version 2.0
|
|
|
|
*/
|
|
|
|
|
2013-03-28 23:36:29 -06:00
|
|
|
#include <stdio.h>
|
|
|
|
#include <stdlib.h>
|
|
|
|
#include <stdint.h>
|
|
|
|
#include <string.h>
|
|
|
|
#include <assert.h>
|
|
|
|
#include <net/if.h>
|
|
|
|
#include <arpa/inet.h>
|
|
|
|
#include <netdb.h>
|
|
|
|
#include <poll.h>
|
|
|
|
#include <unistd.h>
|
|
|
|
#include <signal.h>
|
|
|
|
#include <inttypes.h>
|
|
|
|
#include <sys/socket.h>
|
|
|
|
#include <sys/mman.h>
|
|
|
|
#include <linux/if_packet.h>
|
|
|
|
#include <linux/if_ether.h>
|
|
|
|
#include <linux/ip.h>
|
|
|
|
|
|
|
|
#ifndef likely
|
|
|
|
# define likely(x) __builtin_expect(!!(x), 1)
|
|
|
|
#endif
|
|
|
|
#ifndef unlikely
|
|
|
|
# define unlikely(x) __builtin_expect(!!(x), 0)
|
|
|
|
#endif
|
|
|
|
|
|
|
|
struct block_desc {
|
|
|
|
uint32_t version;
|
|
|
|
uint32_t offset_to_priv;
|
|
|
|
struct tpacket_hdr_v1 h1;
|
|
|
|
};
|
|
|
|
|
|
|
|
struct ring {
|
|
|
|
struct iovec *rd;
|
|
|
|
uint8_t *map;
|
|
|
|
struct tpacket_req3 req;
|
|
|
|
};
|
|
|
|
|
|
|
|
static unsigned long packets_total = 0, bytes_total = 0;
|
|
|
|
static sig_atomic_t sigint = 0;
|
|
|
|
|
2013-06-06 08:08:13 -06:00
|
|
|
static void sighandler(int num)
|
2013-03-28 23:36:29 -06:00
|
|
|
{
|
|
|
|
sigint = 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int setup_socket(struct ring *ring, char *netdev)
|
|
|
|
{
|
|
|
|
int err, i, fd, v = TPACKET_V3;
|
|
|
|
struct sockaddr_ll ll;
|
2013-06-06 08:08:13 -06:00
|
|
|
unsigned int blocksiz = 1 << 22, framesiz = 1 << 11;
|
|
|
|
unsigned int blocknum = 64;
|
2013-03-28 23:36:29 -06:00
|
|
|
|
|
|
|
fd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
|
|
|
|
if (fd < 0) {
|
|
|
|
perror("socket");
|
|
|
|
exit(1);
|
|
|
|
}
|
|
|
|
|
|
|
|
err = setsockopt(fd, SOL_PACKET, PACKET_VERSION, &v, sizeof(v));
|
|
|
|
if (err < 0) {
|
|
|
|
perror("setsockopt");
|
|
|
|
exit(1);
|
|
|
|
}
|
|
|
|
|
|
|
|
memset(&ring->req, 0, sizeof(ring->req));
|
2013-06-06 08:08:13 -06:00
|
|
|
ring->req.tp_block_size = blocksiz;
|
|
|
|
ring->req.tp_frame_size = framesiz;
|
|
|
|
ring->req.tp_block_nr = blocknum;
|
|
|
|
ring->req.tp_frame_nr = (blocksiz * blocknum) / framesiz;
|
|
|
|
ring->req.tp_retire_blk_tov = 60;
|
|
|
|
ring->req.tp_feature_req_word = TP_FT_REQ_FILL_RXHASH;
|
2013-03-28 23:36:29 -06:00
|
|
|
|
|
|
|
err = setsockopt(fd, SOL_PACKET, PACKET_RX_RING, &ring->req,
|
|
|
|
sizeof(ring->req));
|
|
|
|
if (err < 0) {
|
|
|
|
perror("setsockopt");
|
|
|
|
exit(1);
|
|
|
|
}
|
|
|
|
|
|
|
|
ring->map = mmap(NULL, ring->req.tp_block_size * ring->req.tp_block_nr,
|
2013-06-06 08:08:13 -06:00
|
|
|
PROT_READ | PROT_WRITE, MAP_SHARED | MAP_LOCKED, fd, 0);
|
2013-03-28 23:36:29 -06:00
|
|
|
if (ring->map == MAP_FAILED) {
|
|
|
|
perror("mmap");
|
|
|
|
exit(1);
|
|
|
|
}
|
|
|
|
|
|
|
|
ring->rd = malloc(ring->req.tp_block_nr * sizeof(*ring->rd));
|
|
|
|
assert(ring->rd);
|
|
|
|
for (i = 0; i < ring->req.tp_block_nr; ++i) {
|
|
|
|
ring->rd[i].iov_base = ring->map + (i * ring->req.tp_block_size);
|
|
|
|
ring->rd[i].iov_len = ring->req.tp_block_size;
|
|
|
|
}
|
|
|
|
|
|
|
|
memset(&ll, 0, sizeof(ll));
|
|
|
|
ll.sll_family = PF_PACKET;
|
|
|
|
ll.sll_protocol = htons(ETH_P_ALL);
|
|
|
|
ll.sll_ifindex = if_nametoindex(netdev);
|
|
|
|
ll.sll_hatype = 0;
|
|
|
|
ll.sll_pkttype = 0;
|
|
|
|
ll.sll_halen = 0;
|
|
|
|
|
|
|
|
err = bind(fd, (struct sockaddr *) &ll, sizeof(ll));
|
|
|
|
if (err < 0) {
|
|
|
|
perror("bind");
|
|
|
|
exit(1);
|
|
|
|
}
|
|
|
|
|
|
|
|
return fd;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void display(struct tpacket3_hdr *ppd)
|
|
|
|
{
|
|
|
|
struct ethhdr *eth = (struct ethhdr *) ((uint8_t *) ppd + ppd->tp_mac);
|
|
|
|
struct iphdr *ip = (struct iphdr *) ((uint8_t *) eth + ETH_HLEN);
|
|
|
|
|
|
|
|
if (eth->h_proto == htons(ETH_P_IP)) {
|
|
|
|
struct sockaddr_in ss, sd;
|
|
|
|
char sbuff[NI_MAXHOST], dbuff[NI_MAXHOST];
|
|
|
|
|
|
|
|
memset(&ss, 0, sizeof(ss));
|
|
|
|
ss.sin_family = PF_INET;
|
|
|
|
ss.sin_addr.s_addr = ip->saddr;
|
|
|
|
getnameinfo((struct sockaddr *) &ss, sizeof(ss),
|
|
|
|
sbuff, sizeof(sbuff), NULL, 0, NI_NUMERICHOST);
|
|
|
|
|
|
|
|
memset(&sd, 0, sizeof(sd));
|
|
|
|
sd.sin_family = PF_INET;
|
|
|
|
sd.sin_addr.s_addr = ip->daddr;
|
|
|
|
getnameinfo((struct sockaddr *) &sd, sizeof(sd),
|
|
|
|
dbuff, sizeof(dbuff), NULL, 0, NI_NUMERICHOST);
|
|
|
|
|
|
|
|
printf("%s -> %s, ", sbuff, dbuff);
|
|
|
|
}
|
|
|
|
|
|
|
|
printf("rxhash: 0x%x\n", ppd->hv1.tp_rxhash);
|
|
|
|
}
|
|
|
|
|
|
|
|
static void walk_block(struct block_desc *pbd, const int block_num)
|
|
|
|
{
|
2013-06-06 08:08:13 -06:00
|
|
|
int num_pkts = pbd->h1.num_pkts, i;
|
2013-03-28 23:36:29 -06:00
|
|
|
unsigned long bytes = 0;
|
|
|
|
struct tpacket3_hdr *ppd;
|
|
|
|
|
2013-06-06 08:08:13 -06:00
|
|
|
ppd = (struct tpacket3_hdr *) ((uint8_t *) pbd +
|
|
|
|
pbd->h1.offset_to_first_pkt);
|
2013-03-28 23:36:29 -06:00
|
|
|
for (i = 0; i < num_pkts; ++i) {
|
|
|
|
bytes += ppd->tp_snaplen;
|
|
|
|
display(ppd);
|
|
|
|
|
2013-06-06 08:08:13 -06:00
|
|
|
ppd = (struct tpacket3_hdr *) ((uint8_t *) ppd +
|
|
|
|
ppd->tp_next_offset);
|
2013-03-28 23:36:29 -06:00
|
|
|
}
|
|
|
|
|
|
|
|
packets_total += num_pkts;
|
|
|
|
bytes_total += bytes;
|
|
|
|
}
|
|
|
|
|
2013-06-06 08:08:13 -06:00
|
|
|
static void flush_block(struct block_desc *pbd)
|
2013-03-28 23:36:29 -06:00
|
|
|
{
|
2013-06-06 08:08:13 -06:00
|
|
|
pbd->h1.block_status = TP_STATUS_KERNEL;
|
2013-03-28 23:36:29 -06:00
|
|
|
}
|
|
|
|
|
|
|
|
static void teardown_socket(struct ring *ring, int fd)
|
|
|
|
{
|
|
|
|
munmap(ring->map, ring->req.tp_block_size * ring->req.tp_block_nr);
|
|
|
|
free(ring->rd);
|
|
|
|
close(fd);
|
|
|
|
}
|
|
|
|
|
|
|
|
int main(int argc, char **argp)
|
|
|
|
{
|
|
|
|
int fd, err;
|
|
|
|
socklen_t len;
|
|
|
|
struct ring ring;
|
|
|
|
struct pollfd pfd;
|
2013-06-06 08:08:13 -06:00
|
|
|
unsigned int block_num = 0, blocks = 64;
|
2013-03-28 23:36:29 -06:00
|
|
|
struct block_desc *pbd;
|
|
|
|
struct tpacket_stats_v3 stats;
|
|
|
|
|
|
|
|
if (argc != 2) {
|
|
|
|
fprintf(stderr, "Usage: %s INTERFACE\n", argp[0]);
|
|
|
|
return EXIT_FAILURE;
|
|
|
|
}
|
|
|
|
|
|
|
|
signal(SIGINT, sighandler);
|
|
|
|
|
|
|
|
memset(&ring, 0, sizeof(ring));
|
|
|
|
fd = setup_socket(&ring, argp[argc - 1]);
|
|
|
|
assert(fd > 0);
|
|
|
|
|
|
|
|
memset(&pfd, 0, sizeof(pfd));
|
|
|
|
pfd.fd = fd;
|
|
|
|
pfd.events = POLLIN | POLLERR;
|
|
|
|
pfd.revents = 0;
|
|
|
|
|
|
|
|
while (likely(!sigint)) {
|
|
|
|
pbd = (struct block_desc *) ring.rd[block_num].iov_base;
|
2013-06-06 08:08:13 -06:00
|
|
|
|
|
|
|
if ((pbd->h1.block_status & TP_STATUS_USER) == 0) {
|
2013-03-28 23:36:29 -06:00
|
|
|
poll(&pfd, 1, -1);
|
2013-06-06 08:08:13 -06:00
|
|
|
continue;
|
2013-03-28 23:36:29 -06:00
|
|
|
}
|
|
|
|
|
|
|
|
walk_block(pbd, block_num);
|
|
|
|
flush_block(pbd);
|
2013-06-06 08:08:13 -06:00
|
|
|
block_num = (block_num + 1) % blocks;
|
2013-03-28 23:36:29 -06:00
|
|
|
}
|
|
|
|
|
|
|
|
len = sizeof(stats);
|
|
|
|
err = getsockopt(fd, SOL_PACKET, PACKET_STATISTICS, &stats, &len);
|
|
|
|
if (err < 0) {
|
|
|
|
perror("getsockopt");
|
|
|
|
exit(1);
|
|
|
|
}
|
|
|
|
|
|
|
|
fflush(stdout);
|
|
|
|
printf("\nReceived %u packets, %lu bytes, %u dropped, freeze_q_cnt: %u\n",
|
|
|
|
stats.tp_packets, bytes_total, stats.tp_drops,
|
|
|
|
stats.tp_freeze_q_cnt);
|
|
|
|
|
|
|
|
teardown_socket(&ring, fd);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
packet: introduce PACKET_QDISC_BYPASS socket option
This patch introduces a PACKET_QDISC_BYPASS socket option, that
allows for using a similar xmit() function as in pktgen instead
of taking the dev_queue_xmit() path. This can be very useful when
PF_PACKET applications are required to be used in a similar
scenario as pktgen, but with full, flexible packet payload that
needs to be provided, for example.
On default, nothing changes in behaviour for normal PF_PACKET
TX users, so everything stays as is for applications. New users,
however, can now set PACKET_QDISC_BYPASS if needed to prevent
own packets from i) reentering packet_rcv() and ii) to directly
push the frame to the driver.
In doing so we can increase pps (here 64 byte packets) for
PF_PACKET a bit:
# CPUs -- QDISC_BYPASS -- qdisc path -- qdisc path[**]
1 CPU == 1,509,628 pps -- 1,208,708 -- 1,247,436
2 CPUs == 3,198,659 pps -- 2,536,012 -- 1,605,779
3 CPUs == 4,787,992 pps -- 3,788,740 -- 1,735,610
4 CPUs == 6,173,956 pps -- 4,907,799 -- 1,909,114
5 CPUs == 7,495,676 pps -- 5,956,499 -- 2,014,422
6 CPUs == 9,001,496 pps -- 7,145,064 -- 2,155,261
7 CPUs == 10,229,776 pps -- 8,190,596 -- 2,220,619
8 CPUs == 11,040,732 pps -- 9,188,544 -- 2,241,879
9 CPUs == 12,009,076 pps -- 10,275,936 -- 2,068,447
10 CPUs == 11,380,052 pps -- 11,265,337 -- 1,578,689
11 CPUs == 11,672,676 pps -- 11,845,344 -- 1,297,412
[...]
20 CPUs == 11,363,192 pps -- 11,014,933 -- 1,245,081
[**]: qdisc path with packet_rcv(), how probably most people
seem to use it (hopefully not anymore if not needed)
The test was done using a modified trafgen, sending a simple
static 64 bytes packet, on all CPUs. The trick in the fast
"qdisc path" case, is to avoid reentering packet_rcv() by
setting the RAW socket protocol to zero, like:
socket(PF_PACKET, SOCK_RAW, 0);
Tradeoffs are documented as well in this patch, clearly, if
queues are busy, we will drop more packets, tc disciplines are
ignored, and these packets are not visible to taps anymore. For
a pktgen like scenario, we argue that this is acceptable.
The pointer to the xmit function has been placed in packet
socket structure hole between cached_dev and prot_hook that
is hot anyway as we're working on cached_dev in each send path.
Done in joint work together with Jesper Dangaard Brouer.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-12-06 03:36:17 -07:00
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-------------------------------------------------------------------------------
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+ PACKET_QDISC_BYPASS
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-------------------------------------------------------------------------------
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If there is a requirement to load the network with many packets in a similar
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fashion as pktgen does, you might set the following option after socket
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creation:
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int one = 1;
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setsockopt(fd, SOL_PACKET, PACKET_QDISC_BYPASS, &one, sizeof(one));
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This has the side-effect, that packets sent through PF_PACKET will bypass the
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kernel's qdisc layer and are forcedly pushed to the driver directly. Meaning,
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packet are not buffered, tc disciplines are ignored, increased loss can occur
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and such packets are also not visible to other PF_PACKET sockets anymore. So,
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you have been warned; generally, this can be useful for stress testing various
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components of a system.
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On default, PACKET_QDISC_BYPASS is disabled and needs to be explicitly enabled
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on PF_PACKET sockets.
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2010-06-02 06:53:56 -06:00
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-------------------------------------------------------------------------------
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+ PACKET_TIMESTAMP
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-------------------------------------------------------------------------------
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The PACKET_TIMESTAMP setting determines the source of the timestamp in
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2013-04-22 18:39:32 -06:00
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the packet meta information for mmap(2)ed RX_RING and TX_RINGs. If your
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NIC is capable of timestamping packets in hardware, you can request those
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hardware timestamps to be used. Note: you may need to enable the generation
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of hardware timestamps with SIOCSHWTSTAMP (see related information from
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Documentation/networking/timestamping.txt).
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2010-06-02 06:53:56 -06:00
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PACKET_TIMESTAMP accepts the same integer bit field as
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SO_TIMESTAMPING. However, only the SOF_TIMESTAMPING_SYS_HARDWARE
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and SOF_TIMESTAMPING_RAW_HARDWARE values are recognized by
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PACKET_TIMESTAMP. SOF_TIMESTAMPING_SYS_HARDWARE takes precedence over
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SOF_TIMESTAMPING_RAW_HARDWARE if both bits are set.
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int req = 0;
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req |= SOF_TIMESTAMPING_SYS_HARDWARE;
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setsockopt(fd, SOL_PACKET, PACKET_TIMESTAMP, (void *) &req, sizeof(req))
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2013-04-22 18:39:32 -06:00
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For the mmap(2)ed ring buffers, such timestamps are stored in the
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tpacket{,2,3}_hdr structure's tp_sec and tp_{n,u}sec members. To determine
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what kind of timestamp has been reported, the tp_status field is binary |'ed
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with the following possible bits ...
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TP_STATUS_TS_SYS_HARDWARE
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TP_STATUS_TS_RAW_HARDWARE
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TP_STATUS_TS_SOFTWARE
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... that are equivalent to its SOF_TIMESTAMPING_* counterparts. For the
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RX_RING, if none of those 3 are set (i.e. PACKET_TIMESTAMP is not set),
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then this means that a software fallback was invoked *within* PF_PACKET's
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processing code (less precise).
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Getting timestamps for the TX_RING works as follows: i) fill the ring frames,
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ii) call sendto() e.g. in blocking mode, iii) wait for status of relevant
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frames to be updated resp. the frame handed over to the application, iv) walk
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through the frames to pick up the individual hw/sw timestamps.
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Only (!) if transmit timestamping is enabled, then these bits are combined
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with binary | with TP_STATUS_AVAILABLE, so you must check for that in your
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application (e.g. !(tp_status & (TP_STATUS_SEND_REQUEST | TP_STATUS_SENDING))
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in a first step to see if the frame belongs to the application, and then
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one can extract the type of timestamp in a second step from tp_status)!
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If you don't care about them, thus having it disabled, checking for
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TP_STATUS_AVAILABLE resp. TP_STATUS_WRONG_FORMAT is sufficient. If in the
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TX_RING part only TP_STATUS_AVAILABLE is set, then the tp_sec and tp_{n,u}sec
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members do not contain a valid value. For TX_RINGs, by default no timestamp
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is generated!
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2010-06-02 06:53:56 -06:00
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See include/linux/net_tstamp.h and Documentation/networking/timestamping
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for more information on hardware timestamps.
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2012-11-07 19:37:01 -07:00
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-------------------------------------------------------------------------------
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+ Miscellaneous bits
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-------------------------------------------------------------------------------
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- Packet sockets work well together with Linux socket filters, thus you also
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might want to have a look at Documentation/networking/filter.txt
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2005-04-16 16:20:36 -06:00
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--------------------------------------------------------------------------------
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+ THANKS
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--------------------------------------------------------------------------------
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Jesse Brandeburg, for fixing my grammathical/spelling errors
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