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.
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
Reviewed-by: Jesse Brandeburg <jbrandeburg@xxxxxxxxxxxxxx>
Signed-off-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
---
.../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 <stdbool.h>
#include <linux/bpf.h>
+#include <linux/errno.h>
#include <linux/if_ether.h>
#include <linux/pkt_cls.h>
@@ -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
