Re: [PATCH bpf-next v5 09/10] selftests/bpf: move bpf_jit_harden helper into testing_helpers

[Ihor Solodrai <ihor.solodrai@linux.dev>]

On 7/9/26 3:01 AM, Alexis Lothoré (eBPF Foundation) wrote:
> Move set_bpf_jit_harden to testing helpers so that other selftests can
> change the hardening configuration without re-implementing a helper.
> 
> Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
> ---
> Changes in v5:
> - check set_bpf_jit_harden return code in cleanup path
> 
> Changes in v3:
> - new patch
> ---
>  .../selftests/bpf/prog_tests/bpf_insn_array.c      | 44 +++-------------------
>  tools/testing/selftests/bpf/testing_helpers.c      | 32 ++++++++++++++++
>  tools/testing/selftests/bpf/testing_helpers.h      |  1 +
>  3 files changed, 38 insertions(+), 39 deletions(-)

The move makes sense, thanks.

Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>

> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_insn_array.c b/tools/testing/selftests/bpf/prog_tests/bpf_insn_array.c
> index 0222a9a5d076..815f3e04540f 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_insn_array.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_insn_array.c
> @@ -227,42 +227,6 @@ static void check_incorrect_index(void)
>  	check_mid_insn_index();
>  }
>  
> -static int set_bpf_jit_harden(char *level)
> -{
> -	char old_level;
> -	int err = -1;
> -	int fd = -1;
> -
> -	fd = open("/proc/sys/net/core/bpf_jit_harden", O_RDWR | O_NONBLOCK);
> -	if (fd < 0) {
> -		ASSERT_FAIL("open .../bpf_jit_harden returned %d (errno=%d)", fd, errno);
> -		return -1;
> -	}
> -
> -	err = read(fd, &old_level, 1);
> -	if (err != 1) {
> -		ASSERT_FAIL("read from .../bpf_jit_harden returned %d (errno=%d)", err, errno);
> -		err = -1;
> -		goto end;
> -	}
> -
> -	lseek(fd, 0, SEEK_SET);
> -
> -	err = write(fd, level, 1);
> -	if (err != 1) {
> -		ASSERT_FAIL("write to .../bpf_jit_harden returned %d (errno=%d)", err, errno);
> -		err = -1;
> -		goto end;
> -	}
> -
> -	err = 0;
> -	*level = old_level;
> -end:
> -	if (fd >= 0)
> -		close(fd);
> -	return err;
> -}
> -
>  static void check_blindness(void)
>  {
>  	struct bpf_insn insns[] = {
> @@ -272,7 +236,7 @@ static void check_blindness(void)
>  		BPF_MOV64_IMM(BPF_REG_0, 1),
>  		BPF_EXIT_INSN(),
>  	};
> -	int prog_fd = -1, map_fd;
> +	int prog_fd = -1, map_fd, ret;
>  	struct bpf_insn_array_value val = {};
>  	char bpf_jit_harden = '@'; /* non-exizsting value */
>  	int i;
> @@ -291,7 +255,8 @@ static void check_blindness(void)
>  		goto cleanup;
>  
>  	bpf_jit_harden = '2';
> -	if (set_bpf_jit_harden(&bpf_jit_harden)) {
> +	ret = set_bpf_jit_harden(&bpf_jit_harden);
> +	if (!ASSERT_OK(ret, "set bpf_jit_harden")) {
>  		bpf_jit_harden = '@'; /* open, read or write failed => no write was done */
>  		goto cleanup;
>  	}
> @@ -313,7 +278,8 @@ static void check_blindness(void)
>  cleanup:
>  	/* restore the old one */
>  	if (bpf_jit_harden != '@')
> -		set_bpf_jit_harden(&bpf_jit_harden);
> +		ASSERT_OK(set_bpf_jit_harden(&bpf_jit_harden),
> +			  "restore hardening configuration");
>  
>  	close(prog_fd);
>  	close(map_fd);
> diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c
> index c970e7793dfc..737f668b35e2 100644
> --- a/tools/testing/selftests/bpf/testing_helpers.c
> +++ b/tools/testing/selftests/bpf/testing_helpers.c
> @@ -519,6 +519,38 @@ bool is_jit_enabled(void)
>  	return enabled;
>  }
>  
> +int set_bpf_jit_harden(char *level)
> +{
> +	char old_level;
> +	int err = -1;
> +	int fd = -1;
> +
> +	fd = open("/proc/sys/net/core/bpf_jit_harden", O_RDWR | O_NONBLOCK);
> +	if (fd < 0)
> +		return -1;
> +
> +	err = read(fd, &old_level, 1);
> +	if (err != 1) {
> +		err = -1;
> +		goto end;
> +	}
> +
> +	lseek(fd, 0, SEEK_SET);
> +
> +	err = write(fd, level, 1);
> +	if (err != 1) {
> +		err = -1;
> +		goto end;
> +	}
> +
> +	err = 0;
> +	*level = old_level;
> +end:
> +	if (fd >= 0)
> +		close(fd);
> +	return err;
> +}
> +
>  int stack_mprotect(void)
>  {
>  	void *buf;
> diff --git a/tools/testing/selftests/bpf/testing_helpers.h b/tools/testing/selftests/bpf/testing_helpers.h
> index 2edc6fb7fc52..e00642afe86f 100644
> --- a/tools/testing/selftests/bpf/testing_helpers.h
> +++ b/tools/testing/selftests/bpf/testing_helpers.h
> @@ -59,6 +59,7 @@ struct bpf_insn;
>  int get_xlated_program(int fd_prog, struct bpf_insn **buf, __u32 *cnt);
>  int testing_prog_flags(void);
>  bool is_jit_enabled(void);
> +int set_bpf_jit_harden(char *level);
>  int stack_mprotect(void);
>  
>  #endif /* __TESTING_HELPERS_H */
>