> On Oct 16, 2023, at 10:46 PM, Eric Biggers <ebiggers@xxxxxxxxxx> wrote:
>
> On Mon, Oct 16, 2023 at 10:35:16PM -0700, Song Liu wrote:
>> On Mon, Oct 16, 2023 at 8:12 PM Eric Biggers <ebiggers@xxxxxxxxxx> wrote:
>>>
>>> On Mon, Oct 16, 2023 at 01:10:40PM -0700, Song Liu wrote:
>>>> On Sun, Oct 15, 2023 at 12:07 AM Eric Biggers <ebiggers@xxxxxxxxxx> wrote:
>>>>>
>>>> [...]
>>>>>> + */
>>>>>> +__bpf_kfunc int bpf_get_fsverity_digest(struct file *file, struct bpf_dynptr_kern *digest_ptr)
>>>>>> +{
>>>>>> + const struct inode *inode = file_inode(file);
>>>>>> + struct fsverity_digest *arg = digest_ptr->data;
>>>>>
>>>>> What alignment is guaranteed here?
>>>>
>>>> drnptr doesn't not provide alignment guarantee for digest_ptr->data.
>>>> If we need alignment guarantee, we need to add it here.
>>>
>>> So technically it's wrong to cast it to struct fsverity_digest, then.
>>
>> We can enforce alignment here. Would __aligned(2) be sufficient?
>>
>
> Do you mean something like the following:
>
> if (!IS_ALIGNED((uintptr_t)digest_ptr->data, __alignof__(*arg)))
> return -EINVAL;
I was thinking about hard-coding the alignment requirement.
__alignof__ is much better. Thanks for the suggestion!
Song
