Re: [PATCH v16 4/5] random: introduce generic vDSO getrandom() implementation

[Randy Dunlap <rdunlap@infradead.org>]

On 5/28/24 5:19 AM, Jason A. Donenfeld wrote:
> +/**
> + * __cvdso_getrandom_data - Generic vDSO implementation of getrandom() syscall.
> + * @rng_info:		Describes state of kernel RNG, memory shared with kernel.
> + * @buffer:		Destination buffer to fill with random bytes.
> + * @len:		Size of @buffer in bytes.
> + * @flags:		Zero or more GRND_* flags.
> + * @opaque_state:	Pointer to an opaque state area.
> + *
> + * This implements a "fast key erasure" RNG using ChaCha20, in the same way that the kernel's
> + * getrandom() syscall does. It periodically reseeds its key from the kernel's RNG, at the same
> + * schedule that the kernel's RNG is reseeded. If the kernel's RNG is not ready, then this always
> + * calls into the syscall.
> + *
> + * @opaque_state *must* be allocated using the vgetrandom_alloc() syscall.  Unless external locking
> + * is used, one state must be allocated per thread, as it is not safe to call this function
> + * concurrently with the same @opaque_state. However, it is safe to call this using the same
> + * @opaque_state that is shared between main code and signal handling code, within the same thread.
> + *
> + * Returns the number of random bytes written to @buffer, or a negative value indicating an error.

    * Returns:


> + */

-- 
#Randy
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