Re: [PATCHv3 bpf-next 9/9] selftests/bpf: Add file_build_id test

[Daniel Borkmann]

On 3/16/23 6:01 PM, Jiri Olsa wrote:
> The test attaches bpf program to sched_process_exec tracepoint
> and gets build of executed file from bprm->file object.
>
> We use urandom_read as the test program and in addition we also
> attach uprobe to liburandom_read.so:urandlib_read_without_sema
> and retrieve and check build id of that shared library.
>
> Also executing the no_build_id binary to verify the bpf program
> gets the error properly.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
[...]
> diff --git a/tools/testing/selftests/bpf/progs/file_build_id.c b/tools/testing/selftests/bpf/progs/file_build_id.c
> new file mode 100644
> index 000000000000..6dc10c8e17ac
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/file_build_id.c
> @@ -0,0 +1,70 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include "vmlinux.h"
> +#include "err.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include <linux/string.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +int pid;
> +
> +u32 build_id_bin_size;
> +u32 build_id_lib_size;
> +
> +char build_id_bin[BUILD_ID_SIZE_MAX];
> +char build_id_lib[BUILD_ID_SIZE_MAX];
> +
> +long build_id_bin_err;
> +long build_id_lib_err;
> +
> +static int store_build_id(struct file *file, char *build_id, u32 *sz, long *err)
> +{
> +	struct build_id *bid;
> +
> +	bid = file->f_build_id;
> +	if (IS_ERR_OR_NULL(bid)) {

I think you might need to enable this also in the CI config:

  [...]
    CLNG-BPF [test_maps] btf_dump_test_case_multidim.bpf.o
    CLNG-BPF [test_maps] ima.bpf.o
    CLNG-BPF [test_maps] bpf_cubic.bpf.o
  progs/bpf_iter_task_vma_buildid.c:46:27: error: no member named 'f_build_id' in 'struct file'
          if (IS_ERR_OR_NULL(file->f_build_id)) {
                             ~~~~  ^
  progs/bpf_iter_task_vma_buildid.c:51:37: error: no member named 'f_build_id' in 'struct file'
                  __builtin_memcpy(&build_id, file->f_build_id, sizeof(*file->f_build_id));
                                              ~~~~  ^
  progs/bpf_iter_task_vma_buildid.c:51:63: error: no member named 'f_build_id' in 'struct file'
                  __builtin_memcpy(&build_id, file->f_build_id, sizeof(*file->f_build_id));
                                                                        ~~~~  ^
  3 errors generated.
  make: *** [Makefile:578: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/bpf_iter_task_vma_buildid.bpf.o] Error 1
  make: *** Waiting for unfinished jobs....
  make: Leaving directory '/tmp/work/bpf/bpf/tools/testing/selftests/bpf'
  Error: Process completed with exit code 2.

Thanks,
Daniel