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Commit b5a36b1e authored by Lorenz Bauer's avatar Lorenz Bauer Committed by Alexei Starovoitov
Browse files

bpf: respect size hint to BPF_PROG_TEST_RUN if present 



Use data_size_out as a size hint when copying test output to user space.
ENOSPC is returned if the output buffer is too small.
Callers which so far did not set data_size_out are not affected.

Signed-off-by: default avatarLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d59dd69d

include/uapi/linux/bpf.h

+5 −2
Original line number Diff line number Diff line
@@ -374,8 +374,11 @@ union bpf_attr { 
	struct { /* anonymous struct used by BPF_PROG_TEST_RUN command */

		__u32		prog_fd;

		__u32		retval;

		__u32		data_size_in;

		__u32		data_size_out;

		__u32		data_size_in;	/* input: len of data_in */

		__u32		data_size_out;	/* input/output: len of data_out

						 *   returns ENOSPC if data_out

						 *   is too small.

						 */

		__aligned_u64	data_in;

		__aligned_u64	data_out;

		__u32		repeat;

net/bpf/test_run.c

+13 −2
Original line number Diff line number Diff line
@@ -74,8 +74,18 @@ static int bpf_test_finish(const union bpf_attr *kattr, 
{

	void __user *data_out = u64_to_user_ptr(kattr->test.data_out);

	int err = -EFAULT;

	u32 copy_size = size;



	if (data_out && copy_to_user(data_out, data, size))

	/* Clamp copy if the user has provided a size hint, but copy the full

	 * buffer if not to retain old behaviour.

	 */

	if (kattr->test.data_size_out &&

	    copy_size > kattr->test.data_size_out) {

		copy_size = kattr->test.data_size_out;

		err = -ENOSPC;

	}



	if (data_out && copy_to_user(data_out, data, copy_size))

		goto out;

	if (copy_to_user(&uattr->test.data_size_out, &size, sizeof(size)))

		goto out;
@@ -83,6 +93,7 @@ static int bpf_test_finish(const union bpf_attr *kattr, 
		goto out;

	if (copy_to_user(&uattr->test.duration, &duration, sizeof(duration)))

		goto out;

	if (err != -ENOSPC)

		err = 0;

out:

	return err;