From 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 21 Feb 2023 18:24:12 -0800 Subject: Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ... --- Documentation/bpf/map_sockmap.rst | 498 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 498 insertions(+) create mode 100644 Documentation/bpf/map_sockmap.rst (limited to 'Documentation/bpf/map_sockmap.rst') diff --git a/Documentation/bpf/map_sockmap.rst b/Documentation/bpf/map_sockmap.rst new file mode 100644 index 000000000..cc92047c6 --- /dev/null +++ b/Documentation/bpf/map_sockmap.rst @@ -0,0 +1,498 @@ +.. SPDX-License-Identifier: GPL-2.0-only +.. Copyright Red Hat + +============================================== +BPF_MAP_TYPE_SOCKMAP and BPF_MAP_TYPE_SOCKHASH +============================================== + +.. note:: + - ``BPF_MAP_TYPE_SOCKMAP`` was introduced in kernel version 4.14 + - ``BPF_MAP_TYPE_SOCKHASH`` was introduced in kernel version 4.18 + +``BPF_MAP_TYPE_SOCKMAP`` and ``BPF_MAP_TYPE_SOCKHASH`` maps can be used to +redirect skbs between sockets or to apply policy at the socket level based on +the result of a BPF (verdict) program with the help of the BPF helpers +``bpf_sk_redirect_map()``, ``bpf_sk_redirect_hash()``, +``bpf_msg_redirect_map()`` and ``bpf_msg_redirect_hash()``. + +``BPF_MAP_TYPE_SOCKMAP`` is backed by an array that uses an integer key as the +index to look up a reference to a ``struct sock``. The map values are socket +descriptors. Similarly, ``BPF_MAP_TYPE_SOCKHASH`` is a hash backed BPF map that +holds references to sockets via their socket descriptors. + +.. note:: + The value type is either __u32 or __u64; the latter (__u64) is to support + returning socket cookies to userspace. Returning the ``struct sock *`` that + the map holds to user-space is neither safe nor useful. + +These maps may have BPF programs attached to them, specifically a parser program +and a verdict program. The parser program determines how much data has been +parsed and therefore how much data needs to be queued to come to a verdict. The +verdict program is essentially the redirect program and can return a verdict +of ``__SK_DROP``, ``__SK_PASS``, or ``__SK_REDIRECT``. + +When a socket is inserted into one of these maps, its socket callbacks are +replaced and a ``struct sk_psock`` is attached to it. Additionally, this +``sk_psock`` inherits the programs that are attached to the map. + +A sock object may be in multiple maps, but can only inherit a single +parse or verdict program. If adding a sock object to a map would result +in having multiple parser programs the update will return an EBUSY error. + +The supported programs to attach to these maps are: + +.. code-block:: c + + struct sk_psock_progs { + struct bpf_prog *msg_parser; + struct bpf_prog *stream_parser; + struct bpf_prog *stream_verdict; + struct bpf_prog *skb_verdict; + }; + +.. note:: + Users are not allowed to attach ``stream_verdict`` and ``skb_verdict`` + programs to the same map. + +The attach types for the map programs are: + +- ``msg_parser`` program - ``BPF_SK_MSG_VERDICT``. +- ``stream_parser`` program - ``BPF_SK_SKB_STREAM_PARSER``. +- ``stream_verdict`` program - ``BPF_SK_SKB_STREAM_VERDICT``. +- ``skb_verdict`` program - ``BPF_SK_SKB_VERDICT``. + +There are additional helpers available to use with the parser and verdict +programs: ``bpf_msg_apply_bytes()`` and ``bpf_msg_cork_bytes()``. With +``bpf_msg_apply_bytes()`` BPF programs can tell the infrastructure how many +bytes the given verdict should apply to. The helper ``bpf_msg_cork_bytes()`` +handles a different case where a BPF program cannot reach a verdict on a msg +until it receives more bytes AND the program doesn't want to forward the packet +until it is known to be good. + +Finally, the helpers ``bpf_msg_pull_data()`` and ``bpf_msg_push_data()`` are +available to ``BPF_PROG_TYPE_SK_MSG`` BPF programs to pull in data and set the +start and end pointers to given values or to add metadata to the ``struct +sk_msg_buff *msg``. + +All these helpers will be described in more detail below. + +Usage +===== +Kernel BPF +---------- +bpf_msg_redirect_map() +^^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_msg_redirect_map(struct sk_msg_buff *msg, struct bpf_map *map, u32 key, u64 flags) + +This helper is used in programs implementing policies at the socket level. If +the message ``msg`` is allowed to pass (i.e., if the verdict BPF program +returns ``SK_PASS``), redirect it to the socket referenced by ``map`` (of type +``BPF_MAP_TYPE_SOCKMAP``) at index ``key``. Both ingress and egress interfaces +can be used for redirection. The ``BPF_F_INGRESS`` value in ``flags`` is used +to select the ingress path otherwise the egress path is selected. This is the +only flag supported for now. + +Returns ``SK_PASS`` on success, or ``SK_DROP`` on error. + +bpf_sk_redirect_map() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_sk_redirect_map(struct sk_buff *skb, struct bpf_map *map, u32 key u64 flags) + +Redirect the packet to the socket referenced by ``map`` (of type +``BPF_MAP_TYPE_SOCKMAP``) at index ``key``. Both ingress and egress interfaces +can be used for redirection. The ``BPF_F_INGRESS`` value in ``flags`` is used +to select the ingress path otherwise the egress path is selected. This is the +only flag supported for now. + +Returns ``SK_PASS`` on success, or ``SK_DROP`` on error. + +bpf_map_lookup_elem() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + void *bpf_map_lookup_elem(struct bpf_map *map, const void *key) + +socket entries of type ``struct sock *`` can be retrieved using the +``bpf_map_lookup_elem()`` helper. + +bpf_sock_map_update() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_sock_map_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags) + +Add an entry to, or update a ``map`` referencing sockets. The ``skops`` is used +as a new value for the entry associated to ``key``. The ``flags`` argument can +be one of the following: + +- ``BPF_ANY``: Create a new element or update an existing element. +- ``BPF_NOEXIST``: Create a new element only if it did not exist. +- ``BPF_EXIST``: Update an existing element. + +If the ``map`` has BPF programs (parser and verdict), those will be inherited +by the socket being added. If the socket is already attached to BPF programs, +this results in an error. + +Returns 0 on success, or a negative error in case of failure. + +bpf_sock_hash_update() +^^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_sock_hash_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags) + +Add an entry to, or update a sockhash ``map`` referencing sockets. The ``skops`` +is used as a new value for the entry associated to ``key``. + +The ``flags`` argument can be one of the following: + +- ``BPF_ANY``: Create a new element or update an existing element. +- ``BPF_NOEXIST``: Create a new element only if it did not exist. +- ``BPF_EXIST``: Update an existing element. + +If the ``map`` has BPF programs (parser and verdict), those will be inherited +by the socket being added. If the socket is already attached to BPF programs, +this results in an error. + +Returns 0 on success, or a negative error in case of failure. + +bpf_msg_redirect_hash() +^^^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_msg_redirect_hash(struct sk_msg_buff *msg, struct bpf_map *map, void *key, u64 flags) + +This helper is used in programs implementing policies at the socket level. If +the message ``msg`` is allowed to pass (i.e., if the verdict BPF program returns +``SK_PASS``), redirect it to the socket referenced by ``map`` (of type +``BPF_MAP_TYPE_SOCKHASH``) using hash ``key``. Both ingress and egress +interfaces can be used for redirection. The ``BPF_F_INGRESS`` value in +``flags`` is used to select the ingress path otherwise the egress path is +selected. This is the only flag supported for now. + +Returns ``SK_PASS`` on success, or ``SK_DROP`` on error. + +bpf_sk_redirect_hash() +^^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_sk_redirect_hash(struct sk_buff *skb, struct bpf_map *map, void *key, u64 flags) + +This helper is used in programs implementing policies at the skb socket level. +If the sk_buff ``skb`` is allowed to pass (i.e., if the verdict BPF program +returns ``SK_PASS``), redirect it to the socket referenced by ``map`` (of type +``BPF_MAP_TYPE_SOCKHASH``) using hash ``key``. Both ingress and egress +interfaces can be used for redirection. The ``BPF_F_INGRESS`` value in +``flags`` is used to select the ingress path otherwise the egress path is +selected. This is the only flag supported for now. + +Returns ``SK_PASS`` on success, or ``SK_DROP`` on error. + +bpf_msg_apply_bytes() +^^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_msg_apply_bytes(struct sk_msg_buff *msg, u32 bytes) + +For socket policies, apply the verdict of the BPF program to the next (number +of ``bytes``) of message ``msg``. For example, this helper can be used in the +following cases: + +- A single ``sendmsg()`` or ``sendfile()`` system call contains multiple + logical messages that the BPF program is supposed to read and for which it + should apply a verdict. +- A BPF program only cares to read the first ``bytes`` of a ``msg``. If the + message has a large payload, then setting up and calling the BPF program + repeatedly for all bytes, even though the verdict is already known, would + create unnecessary overhead. + +Returns 0 + +bpf_msg_cork_bytes() +^^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_msg_cork_bytes(struct sk_msg_buff *msg, u32 bytes) + +For socket policies, prevent the execution of the verdict BPF program for +message ``msg`` until the number of ``bytes`` have been accumulated. + +This can be used when one needs a specific number of bytes before a verdict can +be assigned, even if the data spans multiple ``sendmsg()`` or ``sendfile()`` +calls. + +Returns 0 + +bpf_msg_pull_data() +^^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_msg_pull_data(struct sk_msg_buff *msg, u32 start, u32 end, u64 flags) + +For socket policies, pull in non-linear data from user space for ``msg`` and set +pointers ``msg->data`` and ``msg->data_end`` to ``start`` and ``end`` bytes +offsets into ``msg``, respectively. + +If a program of type ``BPF_PROG_TYPE_SK_MSG`` is run on a ``msg`` it can only +parse data that the (``data``, ``data_end``) pointers have already consumed. +For ``sendmsg()`` hooks this is likely the first scatterlist element. But for +calls relying on the ``sendpage`` handler (e.g., ``sendfile()``) this will be +the range (**0**, **0**) because the data is shared with user space and by +default the objective is to avoid allowing user space to modify data while (or +after) BPF verdict is being decided. This helper can be used to pull in data +and to set the start and end pointers to given values. Data will be copied if +necessary (i.e., if data was not linear and if start and end pointers do not +point to the same chunk). + +A call to this helper is susceptible to change the underlying packet buffer. +Therefore, at load time, all checks on pointers previously done by the verifier +are invalidated and must be performed again, if the helper is used in +combination with direct packet access. + +All values for ``flags`` are reserved for future usage, and must be left at +zero. + +Returns 0 on success, or a negative error in case of failure. + +bpf_map_lookup_elem() +^^^^^^^^^^^^^^^^^^^^^ + +.. code-block:: c + + void *bpf_map_lookup_elem(struct bpf_map *map, const void *key) + +Look up a socket entry in the sockmap or sockhash map. + +Returns the socket entry associated to ``key``, or NULL if no entry was found. + +bpf_map_update_elem() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_map_update_elem(struct bpf_map *map, const void *key, const void *value, u64 flags) + +Add or update a socket entry in a sockmap or sockhash. + +The flags argument can be one of the following: + +- BPF_ANY: Create a new element or update an existing element. +- BPF_NOEXIST: Create a new element only if it did not exist. +- BPF_EXIST: Update an existing element. + +Returns 0 on success, or a negative error in case of failure. + +bpf_map_delete_elem() +^^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + long bpf_map_delete_elem(struct bpf_map *map, const void *key) + +Delete a socket entry from a sockmap or a sockhash. + +Returns 0 on success, or a negative error in case of failure. + +User space +---------- +bpf_map_update_elem() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + int bpf_map_update_elem(int fd, const void *key, const void *value, __u64 flags) + +Sockmap entries can be added or updated using the ``bpf_map_update_elem()`` +function. The ``key`` parameter is the index value of the sockmap array. And the +``value`` parameter is the FD value of that socket. + +Under the hood, the sockmap update function uses the socket FD value to +retrieve the associated socket and its attached psock. + +The flags argument can be one of the following: + +- BPF_ANY: Create a new element or update an existing element. +- BPF_NOEXIST: Create a new element only if it did not exist. +- BPF_EXIST: Update an existing element. + +bpf_map_lookup_elem() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + int bpf_map_lookup_elem(int fd, const void *key, void *value) + +Sockmap entries can be retrieved using the ``bpf_map_lookup_elem()`` function. + +.. note:: + The entry returned is a socket cookie rather than a socket itself. + +bpf_map_delete_elem() +^^^^^^^^^^^^^^^^^^^^^ +.. code-block:: c + + int bpf_map_delete_elem(int fd, const void *key) + +Sockmap entries can be deleted using the ``bpf_map_delete_elem()`` +function. + +Returns 0 on success, or negative error in case of failure. + +Examples +======== + +Kernel BPF +---------- +Several examples of the use of sockmap APIs can be found in: + +- `tools/testing/selftests/bpf/progs/test_sockmap_kern.h`_ +- `tools/testing/selftests/bpf/progs/sockmap_parse_prog.c`_ +- `tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c`_ +- `tools/testing/selftests/bpf/progs/test_sockmap_listen.c`_ +- `tools/testing/selftests/bpf/progs/test_sockmap_update.c`_ + +The following code snippet shows how to declare a sockmap. + +.. code-block:: c + + struct { + __uint(type, BPF_MAP_TYPE_SOCKMAP); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, __u64); + } sock_map_rx SEC(".maps"); + +The following code snippet shows a sample parser program. + +.. code-block:: c + + SEC("sk_skb/stream_parser") + int bpf_prog_parser(struct __sk_buff *skb) + { + return skb->len; + } + +The following code snippet shows a simple verdict program that interacts with a +sockmap to redirect traffic to another socket based on the local port. + +.. code-block:: c + + SEC("sk_skb/stream_verdict") + int bpf_prog_verdict(struct __sk_buff *skb) + { + __u32 lport = skb->local_port; + __u32 idx = 0; + + if (lport == 10000) + return bpf_sk_redirect_map(skb, &sock_map_rx, idx, 0); + + return SK_PASS; + } + +The following code snippet shows how to declare a sockhash map. + +.. code-block:: c + + struct socket_key { + __u32 src_ip; + __u32 dst_ip; + __u32 src_port; + __u32 dst_port; + }; + + struct { + __uint(type, BPF_MAP_TYPE_SOCKHASH); + __uint(max_entries, 1); + __type(key, struct socket_key); + __type(value, __u64); + } sock_hash_rx SEC(".maps"); + +The following code snippet shows a simple verdict program that interacts with a +sockhash to redirect traffic to another socket based on a hash of some of the +skb parameters. + +.. code-block:: c + + static inline + void extract_socket_key(struct __sk_buff *skb, struct socket_key *key) + { + key->src_ip = skb->remote_ip4; + key->dst_ip = skb->local_ip4; + key->src_port = skb->remote_port >> 16; + key->dst_port = (bpf_htonl(skb->local_port)) >> 16; + } + + SEC("sk_skb/stream_verdict") + int bpf_prog_verdict(struct __sk_buff *skb) + { + struct socket_key key; + + extract_socket_key(skb, &key); + + return bpf_sk_redirect_hash(skb, &sock_hash_rx, &key, 0); + } + +User space +---------- +Several examples of the use of sockmap APIs can be found in: + +- `tools/testing/selftests/bpf/prog_tests/sockmap_basic.c`_ +- `tools/testing/selftests/bpf/test_sockmap.c`_ +- `tools/testing/selftests/bpf/test_maps.c`_ + +The following code sample shows how to create a sockmap, attach a parser and +verdict program, as well as add a socket entry. + +.. code-block:: c + + int create_sample_sockmap(int sock, int parse_prog_fd, int verdict_prog_fd) + { + int index = 0; + int map, err; + + map = bpf_map_create(BPF_MAP_TYPE_SOCKMAP, NULL, sizeof(int), sizeof(int), 1, NULL); + if (map < 0) { + fprintf(stderr, "Failed to create sockmap: %s\n", strerror(errno)); + return -1; + } + + err = bpf_prog_attach(parse_prog_fd, map, BPF_SK_SKB_STREAM_PARSER, 0); + if (err){ + fprintf(stderr, "Failed to attach_parser_prog_to_map: %s\n", strerror(errno)); + goto out; + } + + err = bpf_prog_attach(verdict_prog_fd, map, BPF_SK_SKB_STREAM_VERDICT, 0); + if (err){ + fprintf(stderr, "Failed to attach_verdict_prog_to_map: %s\n", strerror(errno)); + goto out; + } + + err = bpf_map_update_elem(map, &index, &sock, BPF_NOEXIST); + if (err) { + fprintf(stderr, "Failed to update sockmap: %s\n", strerror(errno)); + goto out; + } + + out: + close(map); + return err; + } + +References +=========== + +- https://github.com/jrfastab/linux-kernel-xdp/commit/c89fd73cb9d2d7f3c716c3e00836f07b1aeb261f +- https://lwn.net/Articles/731133/ +- http://vger.kernel.org/lpc_net2018_talks/ktls_bpf_paper.pdf +- https://lwn.net/Articles/748628/ +- https://lore.kernel.org/bpf/20200218171023.844439-7-jakub@cloudflare.com/ + +.. _`tools/testing/selftests/bpf/progs/test_sockmap_kern.h`: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/progs/test_sockmap_kern.h +.. _`tools/testing/selftests/bpf/progs/sockmap_parse_prog.c`: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/progs/sockmap_parse_prog.c +.. _`tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c`: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c +.. _`tools/testing/selftests/bpf/prog_tests/sockmap_basic.c`: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c +.. _`tools/testing/selftests/bpf/test_sockmap.c`: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/test_sockmap.c +.. _`tools/testing/selftests/bpf/test_maps.c`: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/test_maps.c +.. _`tools/testing/selftests/bpf/progs/test_sockmap_listen.c`: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/progs/test_sockmap_listen.c +.. _`tools/testing/selftests/bpf/progs/test_sockmap_update.c`: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/progs/test_sockmap_update.c -- cgit v1.2.3