new file mode 100644
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+void test_skb_ctx(void)
+{
+ struct __sk_buff skb = {
+ .cb[0] = 1,
+ .cb[1] = 2,
+ .cb[2] = 3,
+ .cb[3] = 4,
+ .cb[4] = 5,
+ .priority = 6,
+ };
+ struct bpf_prog_test_run_attr tattr = {
+ .data_in = &pkt_v4,
+ .data_size_in = sizeof(pkt_v4),
+ .ctx_in = &skb,
+ .ctx_size_in = sizeof(skb),
+ .ctx_out = &skb,
+ .ctx_size_out = sizeof(skb),
+ };
+ struct bpf_object *obj;
+ int err;
+ int i;
+
+ err = bpf_prog_load("./test_skb_ctx.o", BPF_PROG_TYPE_SCHED_CLS, &obj,
+ &tattr.prog_fd);
+ if (CHECK_ATTR(err, "load", "err %d errno %d\n", err, errno))
+ return;
+
+ /* ctx_in != NULL, ctx_size_in == 0 */
+
+ tattr.ctx_size_in = 0;
+ err = bpf_prog_test_run_xattr(&tattr);
+ CHECK_ATTR(err == 0, "ctx_size_in", "err %d errno %d\n", err, errno);
+ tattr.ctx_size_in = sizeof(skb);
+
+ /* ctx_out != NULL, ctx_size_out == 0 */
+
+ tattr.ctx_size_out = 0;
+ err = bpf_prog_test_run_xattr(&tattr);
+ CHECK_ATTR(err == 0, "ctx_size_out", "err %d errno %d\n", err, errno);
+ tattr.ctx_size_out = sizeof(skb);
+
+ /* non-zero [len, tc_index] fields should be rejected*/
+
+ skb.len = 1;
+ err = bpf_prog_test_run_xattr(&tattr);
+ CHECK_ATTR(err == 0, "len", "err %d errno %d\n", err, errno);
+ skb.len = 0;
+
+ skb.tc_index = 1;
+ err = bpf_prog_test_run_xattr(&tattr);
+ CHECK_ATTR(err == 0, "tc_index", "err %d errno %d\n", err, errno);
+ skb.tc_index = 0;
+
+ /* non-zero [hash, sk] fields should be rejected */
+
+ skb.hash = 1;
+ err = bpf_prog_test_run_xattr(&tattr);
+ CHECK_ATTR(err == 0, "hash", "err %d errno %d\n", err, errno);
+ skb.hash = 0;
+
+ skb.sk = (struct bpf_sock *)1;
+ err = bpf_prog_test_run_xattr(&tattr);
+ CHECK_ATTR(err == 0, "sk", "err %d errno %d\n", err, errno);
+ skb.sk = 0;
+
+ err = bpf_prog_test_run_xattr(&tattr);
+ CHECK_ATTR(err != 0 || tattr.retval,
+ "run",
+ "err %d errno %d retval %d\n",
+ err, errno, tattr.retval);
+
+ CHECK_ATTR(tattr.ctx_size_out != sizeof(skb),
+ "ctx_size_out",
+ "incorrect output size, want %lu have %u\n",
+ sizeof(skb), tattr.ctx_size_out);
+
+ for (i = 0; i < 5; i++)
+ CHECK_ATTR(skb.cb[i] != i + 2,
+ "ctx_out_cb",
+ "skb->cb[i] == %d, expected %d\n",
+ skb.cb[i], i + 2);
+ CHECK_ATTR(skb.priority != 7,
+ "ctx_out_priority",
+ "skb->priority == %d, expected %d\n",
+ skb.priority, 7);
+}
new file mode 100644
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+int _version SEC("version") = 1;
+char _license[] SEC("license") = "GPL";
+
+SEC("skb_ctx")
+int process(struct __sk_buff *skb)
+{
+ #pragma clang loop unroll(full)
+ for (int i = 0; i < 5; i++) {
+ if (skb->cb[i] != i + 1)
+ return 1;
+ skb->cb[i]++;
+ }
+ skb->priority++;
+
+ return 0;
+}
Simple test that sets cb to {1,2,3,4,5} and priority to 6, runs bpf program that fails if cb is not what we expect and increments cb[i] and priority. When the test finishes, we check that cb is now {2,3,4,5,6} and priority is 7. We also test the sanity checks: * ctx_in is provided, but ctx_size_in is zero (same for ctx_out/ctx_size_out) * unexpected non-zero fields in __sk_buff return EINVAL Cc: Martin Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> --- .../selftests/bpf/prog_tests/skb_ctx.c | 89 +++++++++++++++++++ .../selftests/bpf/progs/test_skb_ctx.c | 21 +++++ 2 files changed, 110 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/skb_ctx.c create mode 100644 tools/testing/selftests/bpf/progs/test_skb_ctx.c