496 lines
12 KiB
C
496 lines
12 KiB
C
#include <stdbool.h>
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#include <linux/bpf.h>
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#include <linux/errno.h>
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#include <linux/if_ether.h>
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#include <linux/pkt_cls.h>
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#include <bpf/bpf_helpers.h>
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#include "bpf_kfuncs.h"
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#define META_SIZE 32
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#define ctx_ptr(ctx, mem) (void *)(unsigned long)ctx->mem
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/* Demonstrates how metadata can be passed from an XDP program to a TC program
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* using bpf_xdp_adjust_meta.
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* For the sake of testing the metadata support in drivers, the XDP program uses
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* a fixed-size payload after the Ethernet header as metadata. The TC program
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* copies the metadata it receives into a map so it can be checked from
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* userspace.
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*/
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__uint(max_entries, 1);
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__type(key, __u32);
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__uint(value_size, META_SIZE);
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} test_result SEC(".maps");
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bool test_pass;
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SEC("tc")
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int ing_cls(struct __sk_buff *ctx)
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{
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__u8 *data, *data_meta;
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__u32 key = 0;
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data_meta = ctx_ptr(ctx, data_meta);
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data = ctx_ptr(ctx, data);
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if (data_meta + META_SIZE > data)
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return TC_ACT_SHOT;
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bpf_map_update_elem(&test_result, &key, data_meta, BPF_ANY);
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return TC_ACT_SHOT;
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}
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/* Read from metadata using bpf_dynptr_read helper */
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SEC("tc")
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int ing_cls_dynptr_read(struct __sk_buff *ctx)
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{
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struct bpf_dynptr meta;
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const __u32 zero = 0;
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__u8 *dst;
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dst = bpf_map_lookup_elem(&test_result, &zero);
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if (!dst)
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return TC_ACT_SHOT;
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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bpf_dynptr_read(dst, META_SIZE, &meta, 0, 0);
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return TC_ACT_SHOT;
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}
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/* Write to metadata using bpf_dynptr_write helper */
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SEC("tc")
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int ing_cls_dynptr_write(struct __sk_buff *ctx)
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{
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struct bpf_dynptr data, meta;
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__u8 *src;
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bpf_dynptr_from_skb(ctx, 0, &data);
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src = bpf_dynptr_slice(&data, sizeof(struct ethhdr), NULL, META_SIZE);
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if (!src)
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return TC_ACT_SHOT;
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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bpf_dynptr_write(&meta, 0, src, META_SIZE, 0);
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return TC_ACT_UNSPEC; /* pass */
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}
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/* Read from metadata using read-only dynptr slice */
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SEC("tc")
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int ing_cls_dynptr_slice(struct __sk_buff *ctx)
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{
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struct bpf_dynptr meta;
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const __u32 zero = 0;
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__u8 *dst, *src;
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dst = bpf_map_lookup_elem(&test_result, &zero);
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if (!dst)
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return TC_ACT_SHOT;
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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src = bpf_dynptr_slice(&meta, 0, NULL, META_SIZE);
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if (!src)
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return TC_ACT_SHOT;
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__builtin_memcpy(dst, src, META_SIZE);
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return TC_ACT_SHOT;
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}
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/* Write to metadata using writeable dynptr slice */
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SEC("tc")
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int ing_cls_dynptr_slice_rdwr(struct __sk_buff *ctx)
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{
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struct bpf_dynptr data, meta;
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__u8 *src, *dst;
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bpf_dynptr_from_skb(ctx, 0, &data);
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src = bpf_dynptr_slice(&data, sizeof(struct ethhdr), NULL, META_SIZE);
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if (!src)
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return TC_ACT_SHOT;
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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dst = bpf_dynptr_slice_rdwr(&meta, 0, NULL, META_SIZE);
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if (!dst)
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return TC_ACT_SHOT;
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__builtin_memcpy(dst, src, META_SIZE);
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return TC_ACT_UNSPEC; /* pass */
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}
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/* Read skb metadata in chunks from various offsets in different ways. */
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SEC("tc")
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int ing_cls_dynptr_offset_rd(struct __sk_buff *ctx)
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{
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struct bpf_dynptr meta;
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const __u32 chunk_len = META_SIZE / 4;
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const __u32 zero = 0;
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__u8 *dst, *src;
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dst = bpf_map_lookup_elem(&test_result, &zero);
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if (!dst)
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return TC_ACT_SHOT;
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/* 1. Regular read */
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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bpf_dynptr_read(dst, chunk_len, &meta, 0, 0);
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dst += chunk_len;
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/* 2. Read from an offset-adjusted dynptr */
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bpf_dynptr_adjust(&meta, chunk_len, bpf_dynptr_size(&meta));
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bpf_dynptr_read(dst, chunk_len, &meta, 0, 0);
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dst += chunk_len;
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/* 3. Read at an offset */
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bpf_dynptr_read(dst, chunk_len, &meta, chunk_len, 0);
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dst += chunk_len;
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/* 4. Read from a slice starting at an offset */
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src = bpf_dynptr_slice(&meta, 2 * chunk_len, NULL, chunk_len);
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if (!src)
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return TC_ACT_SHOT;
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__builtin_memcpy(dst, src, chunk_len);
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return TC_ACT_SHOT;
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}
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/* Write skb metadata in chunks at various offsets in different ways. */
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SEC("tc")
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int ing_cls_dynptr_offset_wr(struct __sk_buff *ctx)
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{
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const __u32 chunk_len = META_SIZE / 4;
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__u8 payload[META_SIZE];
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struct bpf_dynptr meta;
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__u8 *dst, *src;
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bpf_skb_load_bytes(ctx, sizeof(struct ethhdr), payload, sizeof(payload));
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src = payload;
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/* 1. Regular write */
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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bpf_dynptr_write(&meta, 0, src, chunk_len, 0);
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src += chunk_len;
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/* 2. Write to an offset-adjusted dynptr */
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bpf_dynptr_adjust(&meta, chunk_len, bpf_dynptr_size(&meta));
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bpf_dynptr_write(&meta, 0, src, chunk_len, 0);
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src += chunk_len;
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/* 3. Write at an offset */
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bpf_dynptr_write(&meta, chunk_len, src, chunk_len, 0);
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src += chunk_len;
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/* 4. Write to a slice starting at an offset */
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dst = bpf_dynptr_slice_rdwr(&meta, 2 * chunk_len, NULL, chunk_len);
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if (!dst)
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return TC_ACT_SHOT;
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__builtin_memcpy(dst, src, chunk_len);
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return TC_ACT_UNSPEC; /* pass */
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}
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/* Pass an OOB offset to dynptr read, write, adjust, slice. */
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SEC("tc")
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int ing_cls_dynptr_offset_oob(struct __sk_buff *ctx)
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{
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struct bpf_dynptr meta;
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__u8 md, *p;
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int err;
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err = bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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if (err)
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goto fail;
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/* read offset OOB */
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err = bpf_dynptr_read(&md, sizeof(md), &meta, META_SIZE, 0);
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if (err != -E2BIG)
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goto fail;
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/* write offset OOB */
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err = bpf_dynptr_write(&meta, META_SIZE, &md, sizeof(md), 0);
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if (err != -E2BIG)
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goto fail;
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/* adjust end offset OOB */
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err = bpf_dynptr_adjust(&meta, 0, META_SIZE + 1);
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if (err != -ERANGE)
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goto fail;
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/* adjust start offset OOB */
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err = bpf_dynptr_adjust(&meta, META_SIZE + 1, META_SIZE + 1);
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if (err != -ERANGE)
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goto fail;
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/* slice offset OOB */
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p = bpf_dynptr_slice(&meta, META_SIZE, NULL, sizeof(*p));
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if (p)
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goto fail;
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/* slice rdwr offset OOB */
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p = bpf_dynptr_slice_rdwr(&meta, META_SIZE, NULL, sizeof(*p));
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if (p)
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goto fail;
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return TC_ACT_UNSPEC;
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fail:
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return TC_ACT_SHOT;
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}
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/* Reserve and clear space for metadata but don't populate it */
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SEC("xdp")
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int ing_xdp_zalloc_meta(struct xdp_md *ctx)
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{
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struct ethhdr *eth = ctx_ptr(ctx, data);
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__u8 *meta;
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int ret;
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/* Drop any non-test packets */
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if (eth + 1 > ctx_ptr(ctx, data_end))
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return XDP_DROP;
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if (eth->h_proto != 0)
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return XDP_DROP;
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ret = bpf_xdp_adjust_meta(ctx, -META_SIZE);
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if (ret < 0)
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return XDP_DROP;
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meta = ctx_ptr(ctx, data_meta);
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if (meta + META_SIZE > ctx_ptr(ctx, data))
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return XDP_DROP;
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__builtin_memset(meta, 0, META_SIZE);
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return XDP_PASS;
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}
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SEC("xdp")
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int ing_xdp(struct xdp_md *ctx)
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{
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__u8 *data, *data_meta, *data_end, *payload;
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struct ethhdr *eth;
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int ret;
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ret = bpf_xdp_adjust_meta(ctx, -META_SIZE);
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if (ret < 0)
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return XDP_DROP;
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data_meta = ctx_ptr(ctx, data_meta);
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data_end = ctx_ptr(ctx, data_end);
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data = ctx_ptr(ctx, data);
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eth = (struct ethhdr *)data;
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payload = data + sizeof(struct ethhdr);
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if (payload + META_SIZE > data_end ||
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data_meta + META_SIZE > data)
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return XDP_DROP;
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/* The Linux networking stack may send other packets on the test
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* interface that interfere with the test. Just drop them.
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* The test packets can be recognized by their ethertype of zero.
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*/
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if (eth->h_proto != 0)
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return XDP_DROP;
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__builtin_memcpy(data_meta, payload, META_SIZE);
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return XDP_PASS;
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}
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/*
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* Check that skb->data_meta..skb->data is empty if prog writes to packet
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* _payload_ using packet pointers. Applies only to cloned skbs.
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*/
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SEC("tc")
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int clone_data_meta_empty_on_data_write(struct __sk_buff *ctx)
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{
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struct ethhdr *eth = ctx_ptr(ctx, data);
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if (eth + 1 > ctx_ptr(ctx, data_end))
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goto out;
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/* Ignore non-test packets */
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if (eth->h_proto != 0)
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goto out;
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/* Expect no metadata */
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if (ctx->data_meta != ctx->data)
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goto out;
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/* Packet write to trigger unclone in prologue */
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eth->h_proto = 42;
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test_pass = true;
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out:
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return TC_ACT_SHOT;
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}
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/*
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* Check that skb->data_meta..skb->data is empty if prog writes to packet
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* _metadata_ using packet pointers. Applies only to cloned skbs.
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*/
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SEC("tc")
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int clone_data_meta_empty_on_meta_write(struct __sk_buff *ctx)
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{
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struct ethhdr *eth = ctx_ptr(ctx, data);
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__u8 *md = ctx_ptr(ctx, data_meta);
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if (eth + 1 > ctx_ptr(ctx, data_end))
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goto out;
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/* Ignore non-test packets */
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if (eth->h_proto != 0)
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goto out;
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if (md + 1 > ctx_ptr(ctx, data)) {
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/* Expect no metadata */
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test_pass = true;
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} else {
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/* Metadata write to trigger unclone in prologue */
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*md = 42;
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}
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out:
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return TC_ACT_SHOT;
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}
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/*
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* Check that skb_meta dynptr is writable but empty if prog writes to packet
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* _payload_ using a dynptr slice. Applies only to cloned skbs.
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*/
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SEC("tc")
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int clone_dynptr_empty_on_data_slice_write(struct __sk_buff *ctx)
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{
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struct bpf_dynptr data, meta;
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struct ethhdr *eth;
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bpf_dynptr_from_skb(ctx, 0, &data);
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eth = bpf_dynptr_slice_rdwr(&data, 0, NULL, sizeof(*eth));
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if (!eth)
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goto out;
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/* Ignore non-test packets */
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if (eth->h_proto != 0)
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goto out;
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/* Expect no metadata */
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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if (bpf_dynptr_is_rdonly(&meta) || bpf_dynptr_size(&meta) > 0)
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goto out;
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/* Packet write to trigger unclone in prologue */
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eth->h_proto = 42;
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test_pass = true;
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out:
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return TC_ACT_SHOT;
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}
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/*
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* Check that skb_meta dynptr is writable but empty if prog writes to packet
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* _metadata_ using a dynptr slice. Applies only to cloned skbs.
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*/
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SEC("tc")
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int clone_dynptr_empty_on_meta_slice_write(struct __sk_buff *ctx)
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{
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struct bpf_dynptr data, meta;
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const struct ethhdr *eth;
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__u8 *md;
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bpf_dynptr_from_skb(ctx, 0, &data);
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eth = bpf_dynptr_slice(&data, 0, NULL, sizeof(*eth));
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if (!eth)
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goto out;
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/* Ignore non-test packets */
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if (eth->h_proto != 0)
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goto out;
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/* Expect no metadata */
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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if (bpf_dynptr_is_rdonly(&meta) || bpf_dynptr_size(&meta) > 0)
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goto out;
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/* Metadata write to trigger unclone in prologue */
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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md = bpf_dynptr_slice_rdwr(&meta, 0, NULL, sizeof(*md));
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if (md)
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*md = 42;
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test_pass = true;
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out:
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return TC_ACT_SHOT;
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}
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/*
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* Check that skb_meta dynptr is read-only before prog writes to packet payload
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* using dynptr_write helper. Applies only to cloned skbs.
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*/
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SEC("tc")
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int clone_dynptr_rdonly_before_data_dynptr_write(struct __sk_buff *ctx)
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{
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struct bpf_dynptr data, meta;
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const struct ethhdr *eth;
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bpf_dynptr_from_skb(ctx, 0, &data);
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eth = bpf_dynptr_slice(&data, 0, NULL, sizeof(*eth));
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if (!eth)
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goto out;
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/* Ignore non-test packets */
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if (eth->h_proto != 0)
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goto out;
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/* Expect read-only metadata before unclone */
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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if (!bpf_dynptr_is_rdonly(&meta) || bpf_dynptr_size(&meta) != META_SIZE)
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goto out;
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/* Helper write to payload will unclone the packet */
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bpf_dynptr_write(&data, offsetof(struct ethhdr, h_proto), "x", 1, 0);
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/* Expect no metadata after unclone */
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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if (bpf_dynptr_is_rdonly(&meta) || bpf_dynptr_size(&meta) != 0)
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goto out;
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test_pass = true;
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out:
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return TC_ACT_SHOT;
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}
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/*
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* Check that skb_meta dynptr is read-only if prog writes to packet
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* metadata using dynptr_write helper. Applies only to cloned skbs.
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*/
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SEC("tc")
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int clone_dynptr_rdonly_before_meta_dynptr_write(struct __sk_buff *ctx)
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{
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struct bpf_dynptr data, meta;
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const struct ethhdr *eth;
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bpf_dynptr_from_skb(ctx, 0, &data);
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eth = bpf_dynptr_slice(&data, 0, NULL, sizeof(*eth));
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if (!eth)
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goto out;
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/* Ignore non-test packets */
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if (eth->h_proto != 0)
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goto out;
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/* Expect read-only metadata */
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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if (!bpf_dynptr_is_rdonly(&meta) || bpf_dynptr_size(&meta) != META_SIZE)
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goto out;
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/* Metadata write. Expect failure. */
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bpf_dynptr_from_skb_meta(ctx, 0, &meta);
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if (bpf_dynptr_write(&meta, 0, "x", 1, 0) != -EINVAL)
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goto out;
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test_pass = true;
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out:
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return TC_ACT_SHOT;
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}
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char _license[] SEC("license") = "GPL";
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