Exercise r/w access to skb metadata through an offset-adjusted dynptr, read/write helper with an offset argument, and a slice starting at an offset. Also check for the expected errors when the offset is out of bounds. Signed-off-by: Jakub Sitnicki --- .../bpf/prog_tests/xdp_context_test_run.c | 10 ++ tools/testing/selftests/bpf/progs/test_xdp_meta.c | 119 +++++++++++++++++++++ 2 files changed, 129 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c b/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c index 79c4c58276e6..24a7b4b7fdb6 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c @@ -375,6 +375,16 @@ void test_xdp_context_tuntap(void) skel->progs.ing_cls_dynptr_slice_rdwr, skel->progs.ing_cls_dynptr_slice, skel->maps.test_result); + if (test__start_subtest("dynptr_offset")) + test_tuntap(skel->progs.ing_xdp_zalloc_meta, + skel->progs.ing_cls_dynptr_offset_wr, + skel->progs.ing_cls_dynptr_offset_rd, + skel->maps.test_result); + if (test__start_subtest("dynptr_offset_oob")) + test_tuntap(skel->progs.ing_xdp, + skel->progs.ing_cls_dynptr_offset_oob, + skel->progs.ing_cls, + skel->maps.test_result); test_xdp_meta__destroy(skel); } diff --git a/tools/testing/selftests/bpf/progs/test_xdp_meta.c b/tools/testing/selftests/bpf/progs/test_xdp_meta.c index e7879860f403..ee3d8adf5e9c 100644 --- a/tools/testing/selftests/bpf/progs/test_xdp_meta.c +++ b/tools/testing/selftests/bpf/progs/test_xdp_meta.c @@ -1,5 +1,6 @@ #include #include +#include #include #include @@ -122,6 +123,124 @@ int ing_cls_dynptr_slice_rdwr(struct __sk_buff *ctx) return TC_ACT_UNSPEC; /* pass */ } +/* Read skb metadata in chunks from various offsets in different ways. */ +SEC("tc") +int ing_cls_dynptr_offset_rd(struct __sk_buff *ctx) +{ + struct bpf_dynptr meta; + const __u32 chunk_len = META_SIZE / 4; + const __u32 zero = 0; + __u8 *dst, *src; + + dst = bpf_map_lookup_elem(&test_result, &zero); + if (!dst) + return TC_ACT_SHOT; + + /* 1. Regular read */ + bpf_dynptr_from_skb_meta(ctx, 0, &meta); + bpf_dynptr_read(dst, chunk_len, &meta, 0, 0); + dst += chunk_len; + + /* 2. Read from an offset-adjusted dynptr */ + bpf_dynptr_adjust(&meta, chunk_len, bpf_dynptr_size(&meta)); + bpf_dynptr_read(dst, chunk_len, &meta, 0, 0); + dst += chunk_len; + + /* 3. Read at an offset */ + bpf_dynptr_read(dst, chunk_len, &meta, chunk_len, 0); + dst += chunk_len; + + /* 4. Read from a slice starting at an offset */ + src = bpf_dynptr_slice(&meta, 2 * chunk_len, NULL, chunk_len); + if (!src) + return TC_ACT_SHOT; + __builtin_memcpy(dst, src, chunk_len); + + return TC_ACT_SHOT; +} + +/* Write skb metadata in chunks at various offsets in different ways. */ +SEC("tc") +int ing_cls_dynptr_offset_wr(struct __sk_buff *ctx) +{ + const __u32 chunk_len = META_SIZE / 4; + __u8 payload[META_SIZE]; + struct bpf_dynptr meta; + __u8 *dst, *src; + + bpf_skb_load_bytes(ctx, sizeof(struct ethhdr), payload, sizeof(payload)); + src = payload; + + /* 1. Regular write */ + bpf_dynptr_from_skb_meta(ctx, 0, &meta); + bpf_dynptr_write(&meta, 0, src, chunk_len, 0); + src += chunk_len; + + /* 2. Write to an offset-adjusted dynptr */ + bpf_dynptr_adjust(&meta, chunk_len, bpf_dynptr_size(&meta)); + bpf_dynptr_write(&meta, 0, src, chunk_len, 0); + src += chunk_len; + + /* 3. Write at an offset */ + bpf_dynptr_write(&meta, chunk_len, src, chunk_len, 0); + src += chunk_len; + + /* 4. Write to a slice starting at an offset */ + dst = bpf_dynptr_slice_rdwr(&meta, 2 * chunk_len, NULL, chunk_len); + if (!dst) + return TC_ACT_SHOT; + __builtin_memcpy(dst, src, chunk_len); + + return TC_ACT_UNSPEC; /* pass */ +} + +/* Pass an OOB offset to dynptr read, write, adjust, slice. */ +SEC("tc") +int ing_cls_dynptr_offset_oob(struct __sk_buff *ctx) +{ + struct bpf_dynptr meta; + __u8 md, *p; + int err; + + err = bpf_dynptr_from_skb_meta(ctx, 0, &meta); + if (err) + goto fail; + + /* read offset OOB */ + err = bpf_dynptr_read(&md, sizeof(md), &meta, META_SIZE, 0); + if (err != -E2BIG) + goto fail; + + /* write offset OOB */ + err = bpf_dynptr_write(&meta, META_SIZE, &md, sizeof(md), 0); + if (err != -E2BIG) + goto fail; + + /* adjust end offset OOB */ + err = bpf_dynptr_adjust(&meta, 0, META_SIZE + 1); + if (err != -ERANGE) + goto fail; + + /* adjust start offset OOB */ + err = bpf_dynptr_adjust(&meta, META_SIZE + 1, META_SIZE + 1); + if (err != -ERANGE) + goto fail; + + /* slice offset OOB */ + p = bpf_dynptr_slice(&meta, META_SIZE, NULL, sizeof(*p)); + if (p) + goto fail; + + /* slice rdwr offset OOB */ + p = bpf_dynptr_slice_rdwr(&meta, META_SIZE, NULL, sizeof(*p)); + if (p) + goto fail; + + return TC_ACT_UNSPEC; +fail: + return TC_ACT_SHOT; +} + /* Reserve and clear space for metadata but don't populate it */ SEC("xdp") int ing_xdp_zalloc_meta(struct xdp_md *ctx) -- 2.43.0