diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-25 11:17:34 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-25 11:17:34 -0800 |
commit | 4ba9920e5e9c0e16b5ed24292d45322907bb9035 (patch) | |
tree | 7d023baea59ed0886ded1f0b6d1c6385690b88f7 /Documentation | |
parent | 82c477669a4665eb4e52030792051e0559ee2a36 (diff) | |
parent | 8b662fe70c68282f78482dc272df0c4f355e49f5 (diff) |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller:
1) BPF debugger and asm tool by Daniel Borkmann.
2) Speed up create/bind in AF_PACKET, also from Daniel Borkmann.
3) Correct reciprocal_divide and update users, from Hannes Frederic
Sowa and Daniel Borkmann.
4) Currently we only have a "set" operation for the hw timestamp socket
ioctl, add a "get" operation to match. From Ben Hutchings.
5) Add better trace events for debugging driver datapath problems, also
from Ben Hutchings.
6) Implement auto corking in TCP, from Eric Dumazet. Basically, if we
have a small send and a previous packet is already in the qdisc or
device queue, defer until TX completion or we get more data.
7) Allow userspace to manage ipv6 temporary addresses, from Jiri Pirko.
8) Add a qdisc bypass option for AF_PACKET sockets, from Daniel
Borkmann.
9) Share IP header compression code between Bluetooth and IEEE802154
layers, from Jukka Rissanen.
10) Fix ipv6 router reachability probing, from Jiri Benc.
11) Allow packets to be captured on macvtap devices, from Vlad Yasevich.
12) Support tunneling in GRO layer, from Jerry Chu.
13) Allow bonding to be configured fully using netlink, from Scott
Feldman.
14) Allow AF_PACKET users to obtain the VLAN TPID, just like they can
already get the TCI. From Atzm Watanabe.
15) New "Heavy Hitter" qdisc, from Terry Lam.
16) Significantly improve the IPSEC support in pktgen, from Fan Du.
17) Allow ipv4 tunnels to cache routes, just like sockets. From Tom
Herbert.
18) Add Proportional Integral Enhanced packet scheduler, from Vijay
Subramanian.
19) Allow openvswitch to mmap'd netlink, from Thomas Graf.
20) Key TCP metrics blobs also by source address, not just destination
address. From Christoph Paasch.
21) Support 10G in generic phylib. From Andy Fleming.
22) Try to short-circuit GRO flow compares using device provided RX
hash, if provided. From Tom Herbert.
The wireless and netfilter folks have been busy little bees too.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (2064 commits)
net/cxgb4: Fix referencing freed adapter
ipv6: reallocate addrconf router for ipv6 address when lo device up
fib_frontend: fix possible NULL pointer dereference
rtnetlink: remove IFLA_BOND_SLAVE definition
rtnetlink: remove check for fill_slave_info in rtnl_have_link_slave_info
qlcnic: update version to 5.3.55
qlcnic: Enhance logic to calculate msix vectors.
qlcnic: Refactor interrupt coalescing code for all adapters.
qlcnic: Update poll controller code path
qlcnic: Interrupt code cleanup
qlcnic: Enhance Tx timeout debugging.
qlcnic: Use bool for rx_mac_learn.
bonding: fix u64 division
rtnetlink: add missing IFLA_BOND_AD_INFO_UNSPEC
sfc: Use the correct maximum TX DMA ring size for SFC9100
Add Shradha Shah as the sfc driver maintainer.
net/vxlan: Share RX skb de-marking and checksum checks with ovs
tulip: cleanup by using ARRAY_SIZE()
ip_tunnel: clear IPCB in ip_tunnel_xmit() in case dst_link_failure() is called
net/cxgb4: Don't retrieve stats during recovery
...
Diffstat (limited to 'Documentation')
25 files changed, 1115 insertions, 137 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-net-mesh b/Documentation/ABI/testing/sysfs-class-net-mesh index 0baa657b18c..4793d3dff6a 100644 --- a/Documentation/ABI/testing/sysfs-class-net-mesh +++ b/Documentation/ABI/testing/sysfs-class-net-mesh @@ -68,6 +68,14 @@ Description: Defines the penalty which will be applied to an originator message's tq-field on every hop. +What: /sys/class/net/<mesh_iface>/mesh/isolation_mark +Date: Nov 2013 +Contact: Antonio Quartulli <antonio@meshcoding.com> +Description: + Defines the isolation mark (and its bitmask) which + is used to classify clients as "isolated" by the + Extended Isolation feature. + What: /sys/class/net/<mesh_iface>/mesh/network_coding Date: Nov 2012 Contact: Martin Hundeboll <martin@hundeboll.net> diff --git a/Documentation/cgroups/net_cls.txt b/Documentation/cgroups/net_cls.txt index 9face6bb578..ec182346dea 100644 --- a/Documentation/cgroups/net_cls.txt +++ b/Documentation/cgroups/net_cls.txt @@ -6,6 +6,8 @@ tag network packets with a class identifier (classid). The Traffic Controller (tc) can be used to assign different priorities to packets from different cgroups. +Also, Netfilter (iptables) can use this tag to perform +actions on such packets. Creating a net_cls cgroups instance creates a net_cls.classid file. This net_cls.classid value is initialized to 0. @@ -32,3 +34,6 @@ tc class add dev eth0 parent 10: classid 10:1 htb rate 40mbit - creating traffic class 10:1 tc filter add dev eth0 parent 10: protocol ip prio 10 handle 1: cgroup + +configuring iptables, basic example: +iptables -A OUTPUT -m cgroup ! --cgroup 0x100001 -j DROP diff --git a/Documentation/devicetree/bindings/net/allwinner,sun7i-a20-gmac.txt b/Documentation/devicetree/bindings/net/allwinner,sun7i-a20-gmac.txt new file mode 100644 index 00000000000..ea4d752389a --- /dev/null +++ b/Documentation/devicetree/bindings/net/allwinner,sun7i-a20-gmac.txt @@ -0,0 +1,27 @@ +* Allwinner GMAC ethernet controller + +This device is a platform glue layer for stmmac. +Please see stmmac.txt for the other unchanged properties. + +Required properties: + - compatible: Should be "allwinner,sun7i-a20-gmac" + - clocks: Should contain the GMAC main clock, and tx clock + The tx clock type should be "allwinner,sun7i-a20-gmac-clk" + - clock-names: Should contain the clock names "stmmaceth", + and "allwinner_gmac_tx" + +Optional properties: +- phy-supply: phandle to a regulator if the PHY needs one + +Examples: + + gmac: ethernet@01c50000 { + compatible = "allwinner,sun7i-a20-gmac"; + reg = <0x01c50000 0x10000>, + <0x01c20164 0x4>; + interrupts = <0 85 1>; + interrupt-names = "macirq"; + clocks = <&ahb_gates 49>, <&gmac_tx>; + clock-names = "stmmaceth", "allwinner_gmac_tx"; + phy-mode = "mii"; + }; diff --git a/Documentation/devicetree/bindings/net/can/microchip,mcp251x.txt b/Documentation/devicetree/bindings/net/can/microchip,mcp251x.txt new file mode 100644 index 00000000000..ee3723beb70 --- /dev/null +++ b/Documentation/devicetree/bindings/net/can/microchip,mcp251x.txt @@ -0,0 +1,25 @@ +* Microchip MCP251X stand-alone CAN controller device tree bindings + +Required properties: + - compatible: Should be one of the following: + - "microchip,mcp2510" for MCP2510. + - "microchip,mcp2515" for MCP2515. + - reg: SPI chip select. + - clocks: The clock feeding the CAN controller. + - interrupt-parent: The parent interrupt controller. + - interrupts: Should contain IRQ line for the CAN controller. + +Optional properties: + - vdd-supply: Regulator that powers the CAN controller. + - xceiver-supply: Regulator that powers the CAN transceiver. + +Example: + can0: can@1 { + compatible = "microchip,mcp2515"; + reg = <1>; + clocks = <&clk24m>; + interrupt-parent = <&gpio4>; + interrupts = <13 0x2>; + vdd-supply = <®5v0>; + xceiver-supply = <®5v0>; + }; diff --git a/Documentation/devicetree/bindings/net/davinci_emac.txt b/Documentation/devicetree/bindings/net/davinci_emac.txt index bad381faf03..ca0911a20e8 100644 --- a/Documentation/devicetree/bindings/net/davinci_emac.txt +++ b/Documentation/devicetree/bindings/net/davinci_emac.txt @@ -12,8 +12,6 @@ Required properties: - ti,davinci-ctrl-ram-size: size of control module ram - ti,davinci-rmii-en: use RMII - ti,davinci-no-bd-ram: has the emac controller BD RAM -- phy-handle: Contains a phandle to an Ethernet PHY. - if not, davinci_emac driver defaults to 100/FULL - interrupts: interrupt mapping for the davinci emac interrupts sources: 4 sources: <Receive Threshold Interrupt Receive Interrupt @@ -21,6 +19,8 @@ Required properties: Miscellaneous Interrupt> Optional properties: +- phy-handle: Contains a phandle to an Ethernet PHY. + If absent, davinci_emac driver defaults to 100/FULL. - local-mac-address : 6 bytes, mac address Example (enbw_cmc board): diff --git a/Documentation/devicetree/bindings/net/phy.txt b/Documentation/devicetree/bindings/net/phy.txt index 85de6107b98..58307d0931c 100644 --- a/Documentation/devicetree/bindings/net/phy.txt +++ b/Documentation/devicetree/bindings/net/phy.txt @@ -19,6 +19,7 @@ Optional Properties: specifications. If neither of these are specified, the default is to assume clause 22. The compatible list may also contain other elements. +- max-speed: Maximum PHY supported speed (10, 100, 1000...) Example: diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt index eba0e5e59eb..9d92d42140f 100644 --- a/Documentation/devicetree/bindings/net/stmmac.txt +++ b/Documentation/devicetree/bindings/net/stmmac.txt @@ -12,7 +12,6 @@ Required properties: property - phy-mode: String, operation mode of the PHY interface. Supported values are: "mii", "rmii", "gmii", "rgmii". -- snps,phy-addr phy address to connect to. - snps,reset-gpio gpio number for phy reset. - snps,reset-active-low boolean flag to indicate if phy reset is active low. - snps,reset-delays-us is triplet of delays @@ -30,6 +29,11 @@ Required properties: Optional properties: - mac-address: 6 bytes, mac address +- resets: Should contain a phandle to the STMMAC reset signal, if any +- reset-names: Should contain the reset signal name "stmmaceth", if a + reset phandle is given +- max-frame-size: Maximum Transfer Unit (IEEE defined MTU), rather + than the maximum frame size. Examples: @@ -40,5 +44,6 @@ Examples: interrupts = <24 23>; interrupt-names = "macirq", "eth_wake_irq"; mac-address = [000000000000]; /* Filled in by U-Boot */ + max-frame-size = <3800>; phy-mode = "gmii"; }; diff --git a/Documentation/networking/batman-adv.txt b/Documentation/networking/batman-adv.txt index 89490beb3c0..58e49042fc2 100644 --- a/Documentation/networking/batman-adv.txt +++ b/Documentation/networking/batman-adv.txt @@ -66,11 +66,10 @@ All mesh wide settings can be found in batman's own interface folder: # ls /sys/class/net/bat0/mesh/ -# aggregated_ogms gw_bandwidth log_level -# ap_isolation gw_mode orig_interval -# bonding gw_sel_class routing_algo -# bridge_loop_avoidance hop_penalty fragmentation - +#aggregated_ogms distributed_arp_table gw_sel_class orig_interval +#ap_isolation fragmentation hop_penalty routing_algo +#bonding gw_bandwidth isolation_mark vlan0 +#bridge_loop_avoidance gw_mode log_level There is a special folder for debugging information: diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt index 2cdb8b66caa..5cdb22971d1 100644 --- a/Documentation/networking/bonding.txt +++ b/Documentation/networking/bonding.txt @@ -657,7 +657,8 @@ primary one slave is preferred over another, e.g., when one slave has higher throughput than another. - The primary option is only valid for active-backup mode. + The primary option is only valid for active-backup(1), + balance-tlb (5) and balance-alb (6) mode. primary_reselect @@ -853,6 +854,14 @@ resend_igmp This option was added for bonding version 3.7.0. +lp_interval + + Specifies the number of seconds between instances where the bonding + driver sends learning packets to each slaves peer switch. + + The valid range is 1 - 0x7fffffff; the default value is 1. This Option + has effect only in balance-tlb and balance-alb modes. + 3. Configuring Bonding Devices ============================== diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt index 4c072414ead..f3089d42351 100644 --- a/Documentation/networking/can.txt +++ b/Documentation/networking/can.txt @@ -2,21 +2,20 @@ can.txt -Readme file for the Controller Area Network Protocol Family (aka Socket CAN) +Readme file for the Controller Area Network Protocol Family (aka SocketCAN) This file contains - 1 Overview / What is Socket CAN + 1 Overview / What is SocketCAN 2 Motivation / Why using the socket API - 3 Socket CAN concept + 3 SocketCAN concept 3.1 receive lists 3.2 local loopback of sent frames - 3.3 network security issues (capabilities) - 3.4 network problem notifications + 3.3 network problem notifications - 4 How to use Socket CAN + 4 How to use SocketCAN 4.1 RAW protocol sockets with can_filters (SOCK_RAW) 4.1.1 RAW socket option CAN_RAW_FILTER 4.1.2 RAW socket option CAN_RAW_ERR_FILTER @@ -34,7 +33,7 @@ This file contains 4.3 connected transport protocols (SOCK_SEQPACKET) 4.4 unconnected transport protocols (SOCK_DGRAM) - 5 Socket CAN core module + 5 SocketCAN core module 5.1 can.ko module params 5.2 procfs content 5.3 writing own CAN protocol modules @@ -51,20 +50,20 @@ This file contains 6.6 CAN FD (flexible data rate) driver support 6.7 supported CAN hardware - 7 Socket CAN resources + 7 SocketCAN resources 8 Credits ============================================================================ -1. Overview / What is Socket CAN +1. Overview / What is SocketCAN -------------------------------- The socketcan package is an implementation of CAN protocols (Controller Area Network) for Linux. CAN is a networking technology which has widespread use in automation, embedded devices, and automotive fields. While there have been other CAN implementations -for Linux based on character devices, Socket CAN uses the Berkeley +for Linux based on character devices, SocketCAN uses the Berkeley socket API, the Linux network stack and implements the CAN device drivers as network interfaces. The CAN socket API has been designed as similar as possible to the TCP/IP protocols to allow programmers, @@ -74,7 +73,7 @@ sockets. 2. Motivation / Why using the socket API ---------------------------------------- -There have been CAN implementations for Linux before Socket CAN so the +There have been CAN implementations for Linux before SocketCAN so the question arises, why we have started another project. Most existing implementations come as a device driver for some CAN hardware, they are based on character devices and provide comparatively little @@ -89,10 +88,10 @@ the CAN controller requires employment of another device driver and often the need for adaption of large parts of the application to the new driver's API. -Socket CAN was designed to overcome all of these limitations. A new +SocketCAN was designed to overcome all of these limitations. A new protocol family has been implemented which provides a socket interface to user space applications and which builds upon the Linux network -layer, so to use all of the provided queueing functionality. A device +layer, enabling use all of the provided queueing functionality. A device driver for CAN controller hardware registers itself with the Linux network layer as a network device, so that CAN frames from the controller can be passed up to the network layer and on to the CAN @@ -146,15 +145,15 @@ solution for a couple of reasons: providing an API for device drivers to register with. However, then it would be no more difficult, or may be even easier, to use the networking framework provided by the Linux kernel, and this is what - Socket CAN does. + SocketCAN does. The use of the networking framework of the Linux kernel is just the natural and most appropriate way to implement CAN for Linux. -3. Socket CAN concept +3. SocketCAN concept --------------------- - As described in chapter 2 it is the main goal of Socket CAN to + As described in chapter 2 it is the main goal of SocketCAN to provide a socket interface to user space applications which builds upon the Linux network layer. In contrast to the commonly known TCP/IP and ethernet networking, the CAN bus is a broadcast-only(!) @@ -168,11 +167,11 @@ solution for a couple of reasons: The network transparent access of multiple applications leads to the problem that different applications may be interested in the same - CAN-IDs from the same CAN network interface. The Socket CAN core + CAN-IDs from the same CAN network interface. The SocketCAN core module - which implements the protocol family CAN - provides several high efficient receive lists for this reason. If e.g. a user space application opens a CAN RAW socket, the raw protocol module itself - requests the (range of) CAN-IDs from the Socket CAN core that are + requests the (range of) CAN-IDs from the SocketCAN core that are requested by the user. The subscription and unsubscription of CAN-IDs can be done for specific CAN interfaces or for all(!) known CAN interfaces with the can_rx_(un)register() functions provided to @@ -217,21 +216,7 @@ solution for a couple of reasons: * = you really like to have this when you're running analyser tools like 'candump' or 'cansniffer' on the (same) node. - 3.3 network security issues (capabilities) - - The Controller Area Network is a local field bus transmitting only - broadcast messages without any routing and security concepts. - In the majority of cases the user application has to deal with - raw CAN frames. Therefore it might be reasonable NOT to restrict - the CAN access only to the user root, as known from other networks. - Since the currently implemented CAN_RAW and CAN_BCM sockets can only - send and receive frames to/from CAN interfaces it does not affect - security of others networks to allow all users to access the CAN. - To enable non-root users to access CAN_RAW and CAN_BCM protocol - sockets the Kconfig options CAN_RAW_USER and/or CAN_BCM_USER may be - selected at kernel compile time. - - 3.4 network problem notifications + 3.3 network problem notifications The use of the CAN bus may lead to several problems on the physical and media access control layer. Detecting and logging of these lower @@ -251,11 +236,11 @@ solution for a couple of reasons: by default. The format of the CAN error message frame is briefly described in the Linux header file "include/linux/can/error.h". -4. How to use Socket CAN +4. How to use SocketCAN ------------------------ Like TCP/IP, you first need to open a socket for communicating over a - CAN network. Since Socket CAN implements a new protocol family, you + CAN network. Since SocketCAN implements a new protocol family, you need to pass PF_CAN as the first argument to the socket(2) system call. Currently, there are two CAN protocols to choose from, the raw socket protocol and the broadcast manager (BCM). So to open a socket, @@ -286,8 +271,8 @@ solution for a couple of reasons: }; The alignment of the (linear) payload data[] to a 64bit boundary - allows the user to define own structs and unions to easily access the - CAN payload. There is no given byteorder on the CAN bus by + allows the user to define their own structs and unions to easily access + the CAN payload. There is no given byteorder on the CAN bus by default. A read(2) system call on a CAN_RAW socket transfers a struct can_frame to the user space. @@ -479,7 +464,7 @@ solution for a couple of reasons: setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, NULL, 0); - To set the filters to zero filters is quite obsolete as not read + To set the filters to zero filters is quite obsolete as to not read data causes the raw socket to discard the received CAN frames. But having this 'send only' use-case we may remove the receive list in the Kernel to save a little (really a very little!) CPU usage. @@ -814,17 +799,17 @@ solution for a couple of reasons: 4.4 unconnected transport protocols (SOCK_DGRAM) -5. Socket CAN core module +5. SocketCAN core module ------------------------- - The Socket CAN core module implements the protocol family + The SocketCAN core module implements the protocol family PF_CAN. CAN protocol modules are loaded by the core module at runtime. The core module provides an interface for CAN protocol modules to subscribe needed CAN IDs (see chapter 3.1). 5.1 can.ko module params - - stats_timer: To calculate the Socket CAN core statistics + - stats_timer: To calculate the SocketCAN core statistics (e.g. current/maximum frames per second) this 1 second timer is invoked at can.ko module start time by default. This timer can be disabled by using stattimer=0 on the module commandline. @@ -833,7 +818,7 @@ solution for a couple of reasons: 5.2 procfs content - As described in chapter 3.1 the Socket CAN core uses several filter + As described in chapter 3.1 the SocketCAN core uses several filter lists to deliver received CAN frames to CAN protocol modules. These receive lists, their filters and the count of filter matches can be checked in the appropriate receive list. All entries contain the @@ -860,15 +845,15 @@ solution for a couple of reasons: Additional procfs files in /proc/net/can - stats - Socket CAN core statistics (rx/tx frames, match ratios, ...) + stats - SocketCAN core statistics (rx/tx frames, match ratios, ...) reset_stats - manual statistic reset - version - prints the Socket CAN core version and the ABI version + version - prints the SocketCAN core version and the ABI version 5.3 writing own CAN protocol modules To implement a new protocol in the protocol family PF_CAN a new protocol has to be defined in include/linux/can.h . - The prototypes and definitions to use the Socket CAN core can be + The prototypes and definitions to use the SocketCAN core can be accessed by including include/linux/can/core.h . In addition to functions that register the CAN protocol and the CAN device notifier chain there are functions to subscribe CAN @@ -1105,7 +1090,7 @@ solution for a couple of reasons: $ ip link set canX up type can bitrate 125000 - A device may enter the "bus-off" state if too much errors occurred on + A device may enter the "bus-off" state if too many errors occurred on the CAN bus. Then no more messages are received or sent. An automatic bus-off recovery can be enabled by setting the "restart-ms" to a non-zero value, e.g.: @@ -1125,7 +1110,7 @@ solution for a couple of reasons: CAN FD capable CAN controllers support two different bitrates for the arbitration phase and the payload phase of the CAN FD frame. Therefore a - second bittiming has to be specified in order to enable the CAN FD bitrate. + second bit timing has to be specified in order to enable the CAN FD bitrate. Additionally CAN FD capable CAN controllers support up to 64 bytes of payload. The representation of this length in can_frame.can_dlc and @@ -1150,21 +1135,16 @@ solution for a couple of reasons: 6.7 Supported CAN hardware Please check the "Kconfig" file in "drivers/net/can" to get an actual - list of the support CAN hardware. On the Socket CAN project website + list of the support CAN hardware. On the SocketCAN project website (see chapter 7) there might be further drivers available, also for older kernel versions. -7. Socket CAN resources +7. SocketCAN resources ----------------------- - You can find further resources for Socket CAN like user space tools, - support for old kernel versions, more drivers, mailing lists, etc. - at the BerliOS OSS project website for Socket CAN: - - http://developer.berlios.de/projects/socketcan - - If you have questions, bug fixes, etc., don't hesitate to post them to - the Socketcan-Users mailing list. But please search the archives first. + The Linux CAN / SocketCAN project ressources (project site / mailing list) + are referenced in the MAINTAINERS file in the Linux source tree. + Search for CAN NETWORK [LAYERS|DRIVERS]. 8. Credits ---------- diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt index cdb3e40b9d1..a06b48d2f5c 100644 --- a/Documentation/networking/filter.txt +++ b/Documentation/networking/filter.txt @@ -1,49 +1,563 @@ -filter.txt: Linux Socket Filtering -Written by: Jay Schulist <jschlst@samba.org> +Linux Socket Filtering aka Berkeley Packet Filter (BPF) +======================================================= Introduction -============ - - Linux Socket Filtering is derived from the Berkeley -Packet Filter. There are some distinct differences between -the BSD and Linux Kernel Filtering. - -Linux Socket Filtering (LSF) allows a user-space program to -attach a filter onto any socket and allow or disallow certain -types of data to come through the socket. LSF follows exactly -the same filter code structure as the BSD Berkeley Packet Filter -(BPF), so referring to the BSD bpf.4 manpage is very helpful in -creating filters. - -LSF is much simpler than BPF. One does not have to worry about -devices or anything like that. You simply create your filter -code, send it to the kernel via the SO_ATTACH_FILTER option and -if your filter code passes the kernel check on it, you then -immediately begin filtering data on that socket. - -You can also detach filters from your socket via the -SO_DETACH_FILTER option. This will probably not be used much -since when you close a socket that has a filter on it the -filter is automagically removed. The other less common case -may be adding a different filter on the same socket where you had another -filter that is still running: the kernel takes care of removing -the old one and placing your new one in its place, assuming your -filter has passed the checks, otherwise if it fails the old filter -will remain on that socket. - -SO_LOCK_FILTER option allows to lock the filter attached to a -socket. Once set, a filter cannot be removed or changed. This allows -one process to setup a socket, attach a filter, lock it then drop -privileges and be assured that the filter will be kept until the -socket is closed. - -Examples -======== - -Ioctls- -setsockopt(sockfd, SOL_SOCKET, SO_ATTACH_FILTER, &Filter, sizeof(Filter)); -setsockopt(sockfd, SOL_SOCKET, SO_DETACH_FILTER, &value, sizeof(value)); -setsockopt(sockfd, SOL_SOCKET, SO_LOCK_FILTER, &value, sizeof(value)); - -See the BSD bpf.4 manpage and the BSD Packet Filter paper written by -Steven McCanne and Van Jacobson of Lawrence Berkeley Laboratory. +------------ + +Linux Socket Filtering (LSF) is derived from the Berkeley Packet Filter. +Though there are some distinct differences between the BSD and Linux +Kernel filtering, but when we speak of BPF or LSF in Linux context, we +mean the very same mechanism of filtering in the Linux kernel. + +BPF allows a user-space program to attach a filter onto any socket and +allow or disallow certain types of data to come through the socket. LSF +follows exactly the same filter code structure as BSD's BPF, so referring +to the BSD bpf.4 manpage is very helpful in creating filters. + +On Linux, BPF is much simpler than on BSD. One does not have to worry +about devices or anything like that. You simply create your filter code, +send it to the kernel via the SO_ATTACH_FILTER option and if your filter +code passes the kernel check on it, you then immediately begin filtering +data on that socket. + +You can also detach filters from your socket via the SO_DETACH_FILTER +option. This will probably not be used much since when you close a socket +that has a filter on it the filter is automagically removed. The other +less common case may be adding a different filter on the same socket where +you had another filter that is still running: the kernel takes care of +removing the old one and placing your new one in its place, assuming your +filter has passed the checks, otherwise if it fails the old filter will +remain on that socket. + +SO_LOCK_FILTER option allows to lock the filter attached to a socket. Once +set, a filter cannot be removed or changed. This allows one process to +setup a socket, attach a filter, lock it then drop privileges and be +assured that the filter will be kept until the socket is closed. + +The biggest user of this construct might be libpcap. Issuing a high-level +filter command like `tcpdump -i em1 port 22` passes through the libpcap +internal compiler that generates a structure that can eventually be loaded +via SO_ATTACH_FILTER to the kernel. `tcpdump -i em1 port 22 -ddd` +displays what is being placed into this structure. + +Although we were only speaking about sockets here, BPF in Linux is used +in many more places. There's xt_bpf for netfilter, cls_bpf in the kernel +qdisc layer, SECCOMP-BPF (SECure COMPuting [1]), and lots of other places +such as team driver, PTP code, etc where BPF is being used. + + [1] Documentation/prctl/seccomp_filter.txt + +Original BPF paper: + +Steven McCanne and Van Jacobson. 1993. The BSD packet filter: a new +architecture for user-level packet capture. In Proceedings of the +USENIX Winter 1993 Conference Proceedings on USENIX Winter 1993 +Conference Proceedings (USENIX'93). USENIX Association, Berkeley, +CA, USA, 2-2. [http://www.tcpdump.org/papers/bpf-usenix93.pdf] + +Structure +--------- + +User space applications include <linux/filter.h> which contains the +following relevant structures: + +struct sock_filter { /* Filter block */ + __u16 code; /* Actual filter code */ + __u8 jt; /* Jump true */ + __u8 jf; /* Jump false */ + __u32 k; /* Generic multiuse field */ +}; + +Such a structure is assembled as an array of 4-tuples, that contains +a code, jt, jf and k value. jt and jf are jump offsets and k a generic +value to be used for a provided code. + +struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ + unsigned short len; /* Number of filter blocks */ + struct sock_filter __user *filter; +}; + +For socket filtering, a pointer to this structure (as shown in +follow-up example) is being passed to the kernel through setsockopt(2). + +Example +------- + +#include <sys/socket.h> +#include <sys/types.h> +#include <arpa/inet.h> +#include <linux/if_ether.h> +/* ... */ + +/* From the example above: tcpdump -i em1 port 22 -dd */ +struct sock_filter code[] = { + { 0x28, 0, 0, 0x0000000c }, + { 0x15, 0, 8, 0x000086dd }, + { 0x30, 0, 0, 0x00000014 }, + { 0x15, 2, 0, 0x00000084 }, + { 0x15, 1, 0, 0x00000006 }, + { 0x15, 0, 17, 0x00000011 }, + { 0x28, 0, 0, 0x00000036 }, + { 0x15, 14, 0, 0x00000016 }, + { 0x28, 0, 0, 0x00000038 }, + { 0x15, 12, 13, 0x00000016 }, + { 0x15, 0, 12, 0x00000800 }, + { 0x30, 0, 0, 0x00000017 }, + { 0x15, 2, 0, 0x00000084 }, + { 0x15, 1, 0, 0x00000006 }, + { 0x15, 0, 8, 0x00000011 }, + { 0x28, 0, 0, 0x00000014 }, + { 0x45, 6, 0, 0x00001fff }, + { 0xb1, 0, 0, 0x0000000e }, + { 0x48, 0, 0, 0x0000000e }, + { 0x15, 2, 0, 0x00000016 }, + { 0x48, 0, 0, 0x00000010 }, + { 0x15, 0, 1, 0x00000016 }, + { 0x06, 0, 0, 0x0000ffff }, + { 0x06, 0, 0, 0x00000000 }, +}; + +struct sock_fprog bpf = { + .len = ARRAY_SIZE(code), + .filter |