Messages in this thread Patch in this message | | | Date | Thu, 20 Jan 2022 12:50:18 -0500 | From | "Theodore Ts'o" <> | Subject | Re: [PATCH] random: use named fields for adjusting chacha state |
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On Thu, Jan 20, 2022 at 04:07:34PM +0100, Jason A. Donenfeld wrote: > @@ -750,13 +756,13 @@ static bool crng_init_try_arch(struct crng_state *crng) > bool arch_init = true; > unsigned long rv; > > - for (i = 4; i < 16; i++) { > + for (i = 0; i < ARRAY_SIZE(crng->key); i++) { > if (!arch_get_random_seed_long(&rv) && > !arch_get_random_long(&rv)) { > rv = random_get_entropy(); > arch_init = false; > } > - crng->state[i] ^= rv; > + crng->key[i] ^= rv; > }
This change means that we're only initializing the key, but we're not initializing the counter/nonce (well, IV) value. Could you fix this, please?
> @@ -768,13 +774,13 @@ static bool __init crng_init_try_arch_early(struct crng_state *crng) > bool arch_init = true; > unsigned long rv; > > - for (i = 4; i < 16; i++) { > + for (i = 0; i < ARRAY_SIZE(crng->key); i++) { > if (!arch_get_random_seed_long_early(&rv) && > !arch_get_random_long_early(&rv)) { > rv = random_get_entropy(); > arch_init = false; > } > - crng->state[i] ^= rv; > + crng->key[i] ^= rv; > }
Same issue here.
> @@ -783,14 +789,14 @@ static bool __init crng_init_try_arch_early(struct crng_state *crng) > static void crng_initialize_secondary(struct crng_state *crng) > { > chacha_init_consts(crng->state); > - _get_random_bytes(&crng->state[4], sizeof(u32) * 12); > + _get_random_bytes(&crng->key, sizeof(crng->key)); > crng_init_try_arch(crng); > crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; > }
.... and here....
> static void __init crng_initialize_primary(struct crng_state *crng) > { > - _extract_entropy(&crng->state[4], sizeof(u32) * 12); > + _extract_entropy(&crng->key, sizeof(crng->key)); > if (crng_init_try_arch_early(crng) && trust_cpu && crng_init < 2) { > invalidate_batched_entropy(); > numa_crng_init(); > @@ -892,7 +898,7 @@ static size_t crng_fast_load(const u8 *cp, size_t len)
And here....
> @@ -994,9 +1000,9 @@ static void _extract_crng(struct crng_state *crng, u8 out[CHACHA_BLOCK_SIZE]) > crng_reseed(crng, crng == &primary_crng); > } > spin_lock_irqsave(&crng->lock, flags); > - chacha20_block(&crng->state[0], out); > - if (crng->state[12] == 0) > - crng->state[13]++; > + chacha20_block(crng->state, out); > + if (unlikely(!crng->counter[0] && !++crng->counter[1])) > + ++crng->nonce; > spin_unlock_irqrestore(&crng->lock, flags); > }
Minor nit, but I might do this as:
if (unlikely(!crng->counter[0]) && !++crng->counter[1]) ++crng->nonce;
Cheers,
- Ted
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