Re: [PATCH 1/2] random: convert to using fops->read_iter()

Jens Axboe
2022-05-20T03:26:26Z

On 5/19/22 9:11 PM, Al Viro wrote:
> On Thu, May 19, 2022 at 05:31:36PM -0600, Jens Axboe wrote:
>
>> @@ -418,25 +419,23 @@ static ssize_t get_random_bytes_user(void __user *ubuf, size_t len)
>> * the user directly.
>> */
>> if (len <= CHACHA_KEY_SIZE) {
>> - ret = len - copy_to_user(ubuf, &chacha_state[4], len);
>> + ret = copy_to_iter(&chacha_state[4], len, to);
>> goto out_zero_chacha;
>> }
>>
>> for (;;) {
>> + size_t copied;
>> +
>> chacha20_block(chacha_state, output);
>> if (unlikely(chacha_state[12] == 0))
>> ++chacha_state[13];
>>
>> block_len = min_t(size_t, len, CHACHA_BLOCK_SIZE);
>> - left = copy_to_user(ubuf, output, block_len);
>> - if (left) {
>> - ret += block_len - left;
>> + copied = copy_to_iter(output, block_len, to);
>> + ret += copied;
>> + if (copied != block_len)
>> break;
>> - }
>
> copied = copy_to_iter(output, CHACHA_BLOCK_SIZE, to);
> ret += copied;
> if (copied != CHACHA_BLOCK_SIZE) {
> if (!ret)
> ret = -EFAULT;
> break;
> }
> }
>
>> SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags)
>> {
>> + struct iovec iov = { .iov_base = ubuf };
>> + struct iov_iter iter;
>
> import_single_range(READ, ubuf, len, &iov, &iter)
>
> (note, BTW, that this'll cap len)

Yep both of these are good changes.

--
Jens Axboe