On Thu, Apr 22, 2021 at 5:26 PM Alexei Starovoitov
[off-list ref] wrote:

From: Alexei Starovoitov <ast@kernel.org>

Add placeholders for bpf_sys_bpf() helper and new program type.

v1->v2:
- check that expected_attach_type is zero
- allow more helper functions to be used in this program type, since they will
  only execute from user context via bpf_prog_test_run.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

LGTM, see minor comments below.

Acked-by: Andrii Nakryiko <andrii@kernel.org>

 include/linux/bpf.h            | 10 +++++++
 include/linux/bpf_types.h      |  2 ++
 include/uapi/linux/bpf.h       |  8 +++++
 kernel/bpf/syscall.c           | 54 ++++++++++++++++++++++++++++++++++
 net/bpf/test_run.c             | 43 +++++++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  8 +++++
 6 files changed, 125 insertions(+)

[...]

+
+const struct bpf_func_proto * __weak
+tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
+{
+

extra empty line

+       return bpf_base_func_proto(func_id);
+}
+
+static const struct bpf_func_proto *
+syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
+{
+       switch (func_id) {
+       case BPF_FUNC_sys_bpf:
+               return &bpf_sys_bpf_proto;
+       default:
+               return tracing_prog_func_proto(func_id, prog);
+       }
+}
+

[...]

+       if (ctx_size_in) {
+               ctx = kzalloc(ctx_size_in, GFP_USER);
+               if (!ctx)
+                       return -ENOMEM;
+               if (copy_from_user(ctx, ctx_in, ctx_size_in)) {
+                       err = -EFAULT;
+                       goto out;
+               }
+       }
+       retval = bpf_prog_run_pin_on_cpu(prog, ctx);
+
+       if (copy_to_user(&uattr->test.retval, &retval, sizeof(u32)))
+               err = -EFAULT;

is there a point in trying to do another copy_to_user if this fails?
I.e., why not goto out here?

+       if (ctx_size_in)
+               if (copy_to_user(ctx_in, ctx, ctx_size_in)) {
+                       err = -EFAULT;
+                       goto out;
+               }
+out:
+       kfree(ctx);
+       return err;
+}

[...]