diff options
Diffstat (limited to 'tools/testing/selftests/bpf/progs/test_xdp_vlan.c')
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_xdp_vlan.c | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_vlan.c b/tools/testing/selftests/bpf/progs/test_xdp_vlan.c new file mode 100644 index 000000000000..365a7d2d9f5c --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_xdp_vlan.c @@ -0,0 +1,292 @@ +/* SPDX-License-Identifier: GPL-2.0 + * Copyright(c) 2018 Jesper Dangaard Brouer. + * + * XDP/TC VLAN manipulation example + * + * GOTCHA: Remember to disable NIC hardware offloading of VLANs, + * else the VLAN tags are NOT inlined in the packet payload: + * + * # ethtool -K ixgbe2 rxvlan off + * + * Verify setting: + * # ethtool -k ixgbe2 | grep rx-vlan-offload + * rx-vlan-offload: off + * + */ +#include <stddef.h> +#include <stdbool.h> +#include <string.h> +#include <linux/bpf.h> +#include <linux/if_ether.h> +#include <linux/if_vlan.h> +#include <linux/in.h> +#include <linux/pkt_cls.h> + +#include "bpf_helpers.h" +#include "bpf_endian.h" + +/* linux/if_vlan.h have not exposed this as UAPI, thus mirror some here + * + * struct vlan_hdr - vlan header + * @h_vlan_TCI: priority and VLAN ID + * @h_vlan_encapsulated_proto: packet type ID or len + */ +struct _vlan_hdr { + __be16 h_vlan_TCI; + __be16 h_vlan_encapsulated_proto; +}; +#define VLAN_PRIO_MASK 0xe000 /* Priority Code Point */ +#define VLAN_PRIO_SHIFT 13 +#define VLAN_CFI_MASK 0x1000 /* Canonical Format Indicator */ +#define VLAN_TAG_PRESENT VLAN_CFI_MASK +#define VLAN_VID_MASK 0x0fff /* VLAN Identifier */ +#define VLAN_N_VID 4096 + +struct parse_pkt { + __u16 l3_proto; + __u16 l3_offset; + __u16 vlan_outer; + __u16 vlan_inner; + __u8 vlan_outer_offset; + __u8 vlan_inner_offset; +}; + +char _license[] SEC("license") = "GPL"; + +static __always_inline +bool parse_eth_frame(struct ethhdr *eth, void *data_end, struct parse_pkt *pkt) +{ + __u16 eth_type; + __u8 offset; + + offset = sizeof(*eth); + /* Make sure packet is large enough for parsing eth + 2 VLAN headers */ + if ((void *)eth + offset + (2*sizeof(struct _vlan_hdr)) > data_end) + return false; + + eth_type = eth->h_proto; + + /* Handle outer VLAN tag */ + if (eth_type == bpf_htons(ETH_P_8021Q) + || eth_type == bpf_htons(ETH_P_8021AD)) { + struct _vlan_hdr *vlan_hdr; + + vlan_hdr = (void *)eth + offset; + pkt->vlan_outer_offset = offset; + pkt->vlan_outer = bpf_ntohs(vlan_hdr->h_vlan_TCI) + & VLAN_VID_MASK; + eth_type = vlan_hdr->h_vlan_encapsulated_proto; + offset += sizeof(*vlan_hdr); + } + + /* Handle inner (double) VLAN tag */ + if (eth_type == bpf_htons(ETH_P_8021Q) + || eth_type == bpf_htons(ETH_P_8021AD)) { + struct _vlan_hdr *vlan_hdr; + + vlan_hdr = (void *)eth + offset; + pkt->vlan_inner_offset = offset; + pkt->vlan_inner = bpf_ntohs(vlan_hdr->h_vlan_TCI) + & VLAN_VID_MASK; + eth_type = vlan_hdr->h_vlan_encapsulated_proto; + offset += sizeof(*vlan_hdr); + } + + pkt->l3_proto = bpf_ntohs(eth_type); /* Convert to host-byte-order */ + pkt->l3_offset = offset; + + return true; +} + +/* Hint, VLANs are choosen to hit network-byte-order issues */ +#define TESTVLAN 4011 /* 0xFAB */ +// #define TO_VLAN 4000 /* 0xFA0 (hint 0xOA0 = 160) */ + +SEC("xdp_drop_vlan_4011") +int xdp_prognum0(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct parse_pkt pkt = { 0 }; + + if (!parse_eth_frame(data, data_end, &pkt)) + return XDP_ABORTED; + + /* Drop specific VLAN ID example */ + if (pkt.vlan_outer == TESTVLAN) + return XDP_ABORTED; + /* + * Using XDP_ABORTED makes it possible to record this event, + * via tracepoint xdp:xdp_exception like: + * # perf record -a -e xdp:xdp_exception + * # perf script + */ + return XDP_PASS; +} +/* +Commands to setup VLAN on Linux to test packets gets dropped: + + export ROOTDEV=ixgbe2 + export VLANID=4011 + ip link add link $ROOTDEV name $ROOTDEV.$VLANID type vlan id $VLANID + ip link set dev $ROOTDEV.$VLANID up + + ip link set dev $ROOTDEV mtu 1508 + ip addr add 100.64.40.11/24 dev $ROOTDEV.$VLANID + +Load prog with ip tool: + + ip link set $ROOTDEV xdp off + ip link set $ROOTDEV xdp object xdp_vlan01_kern.o section xdp_drop_vlan_4011 + +*/ + +/* Changing VLAN to zero, have same practical effect as removing the VLAN. */ +#define TO_VLAN 0 + +SEC("xdp_vlan_change") +int xdp_prognum1(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct parse_pkt pkt = { 0 }; + + if (!parse_eth_frame(data, data_end, &pkt)) + return XDP_ABORTED; + + /* Change specific VLAN ID */ + if (pkt.vlan_outer == TESTVLAN) { + struct _vlan_hdr *vlan_hdr = data + pkt.vlan_outer_offset; + + /* Modifying VLAN, preserve top 4 bits */ + vlan_hdr->h_vlan_TCI = + bpf_htons((bpf_ntohs(vlan_hdr->h_vlan_TCI) & 0xf000) + | TO_VLAN); + } + + return XDP_PASS; +} + +/* + * Show XDP+TC can cooperate, on creating a VLAN rewriter. + * 1. Create a XDP prog that can "pop"/remove a VLAN header. + * 2. Create a TC-bpf prog that egress can add a VLAN header. + */ + +#ifndef ETH_ALEN /* Ethernet MAC address length */ +#define ETH_ALEN 6 /* bytes */ +#endif +#define VLAN_HDR_SZ 4 /* bytes */ + +SEC("xdp_vlan_remove_outer") +int xdp_prognum2(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct parse_pkt pkt = { 0 }; + char *dest; + + if (!parse_eth_frame(data, data_end, &pkt)) + return XDP_ABORTED; + + /* Skip packet if no outer VLAN was detected */ + if (pkt.vlan_outer_offset == 0) + return XDP_PASS; + + /* Moving Ethernet header, dest overlap with src, memmove handle this */ + dest = data; + dest+= VLAN_HDR_SZ; + /* + * Notice: Taking over vlan_hdr->h_vlan_encapsulated_proto, by + * only moving two MAC addrs (12 bytes), not overwriting last 2 bytes + */ + __builtin_memmove(dest, data, ETH_ALEN * 2); + /* Note: LLVM built-in memmove inlining require size to be constant */ + + /* Move start of packet header seen by Linux kernel stack */ + bpf_xdp_adjust_head(ctx, VLAN_HDR_SZ); + + return XDP_PASS; +} + +static __always_inline +void shift_mac_4bytes_16bit(void *data) +{ + __u16 *p = data; + + p[7] = p[5]; /* delete p[7] was vlan_hdr->h_vlan_TCI */ + p[6] = p[4]; /* delete p[6] was ethhdr->h_proto */ + p[5] = p[3]; + p[4] = p[2]; + p[3] = p[1]; + p[2] = p[0]; +} + +static __always_inline +void shift_mac_4bytes_32bit(void *data) +{ + __u32 *p = data; + + /* Assuming VLAN hdr present. The 4 bytes in p[3] that gets + * overwritten, is ethhdr->h_proto and vlan_hdr->h_vlan_TCI. + * The vlan_hdr->h_vlan_encapsulated_proto take over role as + * ethhdr->h_proto. + */ + p[3] = p[2]; + p[2] = p[1]; + p[1] = p[0]; +} + +SEC("xdp_vlan_remove_outer2") +int xdp_prognum3(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + struct ethhdr *orig_eth = data; + struct parse_pkt pkt = { 0 }; + + if (!parse_eth_frame(orig_eth, data_end, &pkt)) + return XDP_ABORTED; + + /* Skip packet if no outer VLAN was detected */ + if (pkt.vlan_outer_offset == 0) + return XDP_PASS; + + /* Simply shift down MAC addrs 4 bytes, overwrite h_proto + TCI */ + shift_mac_4bytes_32bit(data); + + /* Move start of packet header seen by Linux kernel stack */ + bpf_xdp_adjust_head(ctx, VLAN_HDR_SZ); + + return XDP_PASS; +} + +/*===================================== + * BELOW: TC-hook based ebpf programs + * ==================================== + * The TC-clsact eBPF programs (currently) need to be attach via TC commands + */ + +SEC("tc_vlan_push") +int _tc_progA(struct __sk_buff *ctx) +{ + bpf_skb_vlan_push(ctx, bpf_htons(ETH_P_8021Q), TESTVLAN); + + return TC_ACT_OK; +} +/* +Commands to setup TC to use above bpf prog: + +export ROOTDEV=ixgbe2 +export FILE=xdp_vlan01_kern.o + +# Re-attach clsact to clear/flush existing role +tc qdisc del dev $ROOTDEV clsact 2> /dev/null ;\ +tc qdisc add dev $ROOTDEV clsact + +# Attach BPF prog EGRESS +tc filter add dev $ROOTDEV egress \ + prio 1 handle 1 bpf da obj $FILE sec tc_vlan_push + +tc filter show dev $ROOTDEV egress +*/ |