From c50e96099edb134bf107fafc02715fbc4aa2277f Mon Sep 17 00:00:00 2001 From: Christian Ehrig Date: Fri, 7 Apr 2023 15:38:54 +0200 Subject: [PATCH] bpf,fou: Add bpf_skb_{set,get}_fou_encap kfuncs Add two new kfuncs that allow a BPF tc-hook, installed on an ipip device in collect-metadata mode, to control FOU encap parameters on a per-packet level. The set of kfuncs is registered with the fou module. The bpf_skb_set_fou_encap kfunc is supposed to be used in tandem and after a successful call to the bpf_skb_set_tunnel_key bpf-helper. UDP source and destination ports can be controlled by passing a struct bpf_fou_encap. A source port of zero will auto-assign a source port. enum bpf_fou_encap_type is used to specify if the egress path should FOU or GUE encap the packet. On the ingress path bpf_skb_get_fou_encap can be used to read UDP source and destination ports from the receiver's point of view and allows for packet multiplexing across different destination ports within a single BPF program and ipip device. Signed-off-by: Christian Ehrig Link: https://lore.kernel.org/r/e17c94a646b63e78ce0dbf3f04b2c33dc948a32d.1680874078.git.cehrig@cloudflare.com Signed-off-by: Alexei Starovoitov --- include/net/fou.h | 2 + net/ipv4/Makefile | 2 +- net/ipv4/fou_bpf.c | 119 ++++++++++++++++++++++++++++++++++++++++++++ net/ipv4/fou_core.c | 5 ++ 4 files changed, 127 insertions(+), 1 deletion(-) create mode 100644 net/ipv4/fou_bpf.c diff --git a/include/net/fou.h b/include/net/fou.h index 80f56e275b08..824eb4b231fd 100644 --- a/include/net/fou.h +++ b/include/net/fou.h @@ -17,4 +17,6 @@ int __fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e, int __gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e, u8 *protocol, __be16 *sport, int type); +int register_fou_bpf(void); + #endif diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile index 880277c9fd07..b18ba8ef93ad 100644 --- a/net/ipv4/Makefile +++ b/net/ipv4/Makefile @@ -26,7 +26,7 @@ obj-$(CONFIG_IP_MROUTE) += ipmr.o obj-$(CONFIG_IP_MROUTE_COMMON) += ipmr_base.o obj-$(CONFIG_NET_IPIP) += ipip.o gre-y := gre_demux.o -fou-y := fou_core.o fou_nl.o +fou-y := fou_core.o fou_nl.o fou_bpf.o obj-$(CONFIG_NET_FOU) += fou.o obj-$(CONFIG_NET_IPGRE_DEMUX) += gre.o obj-$(CONFIG_NET_IPGRE) += ip_gre.o diff --git a/net/ipv4/fou_bpf.c b/net/ipv4/fou_bpf.c new file mode 100644 index 000000000000..3760a14b6b57 --- /dev/null +++ b/net/ipv4/fou_bpf.c @@ -0,0 +1,119 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Unstable Fou Helpers for TC-BPF hook + * + * These are called from SCHED_CLS BPF programs. Note that it is + * allowed to break compatibility for these functions since the interface they + * are exposed through to BPF programs is explicitly unstable. + */ + +#include +#include + +#include +#include + +struct bpf_fou_encap { + __be16 sport; + __be16 dport; +}; + +enum bpf_fou_encap_type { + FOU_BPF_ENCAP_FOU, + FOU_BPF_ENCAP_GUE, +}; + +__diag_push(); +__diag_ignore_all("-Wmissing-prototypes", + "Global functions as their definitions will be in BTF"); + +/* bpf_skb_set_fou_encap - Set FOU encap parameters + * + * This function allows for using GUE or FOU encapsulation together with an + * ipip device in collect-metadata mode. + * + * It is meant to be used in BPF tc-hooks and after a call to the + * bpf_skb_set_tunnel_key helper, responsible for setting IP addresses. + * + * Parameters: + * @skb_ctx Pointer to ctx (__sk_buff) in TC program. Cannot be NULL + * @encap Pointer to a `struct bpf_fou_encap` storing UDP src and + * dst ports. If sport is set to 0 the kernel will auto-assign a + * port. This is similar to using `encap-sport auto`. + * Cannot be NULL + * @type Encapsulation type for the packet. Their definitions are + * specified in `enum bpf_fou_encap_type` + */ +__bpf_kfunc int bpf_skb_set_fou_encap(struct __sk_buff *skb_ctx, + struct bpf_fou_encap *encap, int type) +{ + struct sk_buff *skb = (struct sk_buff *)skb_ctx; + struct ip_tunnel_info *info = skb_tunnel_info(skb); + + if (unlikely(!encap)) + return -EINVAL; + + if (unlikely(!info || !(info->mode & IP_TUNNEL_INFO_TX))) + return -EINVAL; + + switch (type) { + case FOU_BPF_ENCAP_FOU: + info->encap.type = TUNNEL_ENCAP_FOU; + break; + case FOU_BPF_ENCAP_GUE: + info->encap.type = TUNNEL_ENCAP_GUE; + break; + default: + info->encap.type = TUNNEL_ENCAP_NONE; + } + + if (info->key.tun_flags & TUNNEL_CSUM) + info->encap.flags |= TUNNEL_ENCAP_FLAG_CSUM; + + info->encap.sport = encap->sport; + info->encap.dport = encap->dport; + + return 0; +} + +/* bpf_skb_get_fou_encap - Get FOU encap parameters + * + * This function allows for reading encap metadata from a packet received + * on an ipip device in collect-metadata mode. + * + * Parameters: + * @skb_ctx Pointer to ctx (__sk_buff) in TC program. Cannot be NULL + * @encap Pointer to a struct bpf_fou_encap storing UDP source and + * destination port. Cannot be NULL + */ +__bpf_kfunc int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx, + struct bpf_fou_encap *encap) +{ + struct sk_buff *skb = (struct sk_buff *)skb_ctx; + struct ip_tunnel_info *info = skb_tunnel_info(skb); + + if (unlikely(!info)) + return -EINVAL; + + encap->sport = info->encap.sport; + encap->dport = info->encap.dport; + + return 0; +} + +__diag_pop() + +BTF_SET8_START(fou_kfunc_set) +BTF_ID_FLAGS(func, bpf_skb_set_fou_encap) +BTF_ID_FLAGS(func, bpf_skb_get_fou_encap) +BTF_SET8_END(fou_kfunc_set) + +static const struct btf_kfunc_id_set fou_bpf_kfunc_set = { + .owner = THIS_MODULE, + .set = &fou_kfunc_set, +}; + +int register_fou_bpf(void) +{ + return register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, + &fou_bpf_kfunc_set); +} diff --git a/net/ipv4/fou_core.c b/net/ipv4/fou_core.c index cafec9b4eee0..0c41076e31ed 100644 --- a/net/ipv4/fou_core.c +++ b/net/ipv4/fou_core.c @@ -1236,10 +1236,15 @@ static int __init fou_init(void) if (ret < 0) goto unregister; + ret = register_fou_bpf(); + if (ret < 0) + goto kfunc_failed; + ret = ip_tunnel_encap_add_fou_ops(); if (ret == 0) return 0; +kfunc_failed: genl_unregister_family(&fou_nl_family); unregister: unregister_pernet_device(&fou_net_ops);