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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: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Lorenz Bauer 2018-12-03 11:31:23 +00:00 committed by Alexei Starovoitov
parent d59dd69d55
commit b5a36b1e1b
2 changed files with 18 additions and 4 deletions
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7
include/uapi/linux/bpf.h
View File

@ -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;

15
net/bpf/test_run.c
View File

@ -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;
@ -83,7 +93,8 @@ static int bpf_test_finish(const union bpf_attr *kattr,
goto out;
if (copy_to_user(&uattr->test.duration, &duration, sizeof(duration)))
goto out;
err = 0;
if (err != -ENOSPC)
err = 0;
out:
return err;
}