svn commit: r355018 - in head/sys: dev/random sys
Conrad Meyer
cem at freebsd.org
Fri Nov 22 21:07:25 UTC 2019
It wasn't lost in the change. The parameters now have the names
"entropy" and "len," but it is the same functionality.
Best,
Conrad
On Fri, Nov 22, 2019 at 12:56 PM Ravi Pokala <rpokala at freebsd.org> wrote:
>
> Hi Conrad,
>
> The original code did
>
> explicit_bzero(data, size);
>
> which appears to have been lost in this change. Is that intentional? If so, why is that okay?
>
> Thanks,
>
> Ravi (rpokala@)
>
> -----Original Message-----
> From: <owner-src-committers at freebsd.org> on behalf of Conrad Meyer <cem at FreeBSD.org>
> Date: 2019-11-22, Friday at 12:20
> To: <src-committers at freebsd.org>, <svn-src-all at freebsd.org>, <svn-src-head at freebsd.org>
> Subject: svn commit: r355018 - in head/sys: dev/random sys
>
> Author: cem
> Date: Fri Nov 22 20:20:37 2019
> New Revision: 355018
> URL: https://svnweb.freebsd.org/changeset/base/355018
>
> Log:
> random(4): Abstract loader entropy injection
>
> Break random_harvestq_prime up into some logical subroutines. The goal
> is that it becomes easier to add other early entropy sources.
>
> While here, drop pre-12.0 compatibility logic. loader default configuration
> should preload the file as expeced since 12.0.
>
> Approved by: csprng(delphij, markm)
> Differential Revision: https://reviews.freebsd.org/D22482
>
> Modified:
> head/sys/dev/random/random_harvestq.c
> head/sys/sys/random.h
>
> Modified: head/sys/dev/random/random_harvestq.c
> ==============================================================================
> --- head/sys/dev/random/random_harvestq.c Fri Nov 22 20:18:07 2019 (r355017)
> +++ head/sys/dev/random/random_harvestq.c Fri Nov 22 20:20:37 2019 (r355018)
> @@ -402,6 +402,57 @@ random_harvestq_init(void *unused __unused)
> SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_SECOND, random_harvestq_init, NULL);
>
> /*
> + * Subroutine to slice up a contiguous chunk of 'entropy' and feed it into the
> + * underlying algorithm. Returns number of bytes actually fed into underlying
> + * algorithm.
> + */
> +static size_t
> +random_early_prime(char *entropy, size_t len)
> +{
> + struct harvest_event event;
> + size_t i;
> +
> + len = rounddown(len, sizeof(event.he_entropy));
> + if (len == 0)
> + return (0);
> +
> + for (i = 0; i < len; i += sizeof(event.he_entropy)) {
> + event.he_somecounter = (uint32_t)get_cyclecount();
> + event.he_size = sizeof(event.he_entropy);
> + event.he_source = RANDOM_CACHED;
> + event.he_destination =
> + harvest_context.hc_destination[RANDOM_CACHED]++;
> + memcpy(event.he_entropy, entropy + i, sizeof(event.he_entropy));
> + random_harvestq_fast_process_event(&event);
> + }
> + explicit_bzero(entropy, len);
> + return (len);
> +}
> +
> +/*
> + * Subroutine to search for known loader-loaded files in memory and feed them
> + * into the underlying algorithm early in boot. Returns the number of bytes
> + * loaded (zero if none were loaded).
> + */
> +static size_t
> +random_prime_loader_file(const char *type)
> +{
> + uint8_t *keyfile, *data;
> + size_t size;
> +
> + keyfile = preload_search_by_type(type);
> + if (keyfile == NULL)
> + return (0);
> +
> + data = preload_fetch_addr(keyfile);
> + size = preload_fetch_size(keyfile);
> + if (data == NULL)
> + return (0);
> +
> + return (random_early_prime(data, size));
> +}
> +
> +/*
> * This is used to prime the RNG by grabbing any early random stuff
> * known to the kernel, and inserting it directly into the hashing
> * module, currently Fortuna.
> @@ -410,41 +461,19 @@ SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_
> static void
> random_harvestq_prime(void *unused __unused)
> {
> - struct harvest_event event;
> - size_t count, size, i;
> - uint8_t *keyfile, *data;
> + size_t size;
>
> /*
> * Get entropy that may have been preloaded by loader(8)
> * and use it to pre-charge the entropy harvest queue.
> */
> - keyfile = preload_search_by_type(RANDOM_CACHED_BOOT_ENTROPY_MODULE);
> -#ifndef NO_BACKWARD_COMPATIBILITY
> - if (keyfile == NULL)
> - keyfile = preload_search_by_type(RANDOM_LEGACY_BOOT_ENTROPY_MODULE);
> -#endif
> - if (keyfile != NULL) {
> - data = preload_fetch_addr(keyfile);
> - size = preload_fetch_size(keyfile);
> - /* Trim the size. If the admin has a file with a funny size, we lose some. Tough. */
> - size -= (size % sizeof(event.he_entropy));
> - if (data != NULL && size != 0) {
> - for (i = 0; i < size; i += sizeof(event.he_entropy)) {
> - count = sizeof(event.he_entropy);
> - event.he_somecounter = (uint32_t)get_cyclecount();
> - event.he_size = count;
> - event.he_source = RANDOM_CACHED;
> - event.he_destination =
> - harvest_context.hc_destination[RANDOM_CACHED]++;
> - memcpy(event.he_entropy, data + i, sizeof(event.he_entropy));
> - random_harvestq_fast_process_event(&event);
> - }
> - explicit_bzero(data, size);
> - if (bootverbose)
> - printf("random: read %zu bytes from preloaded cache\n", size);
> - } else
> - if (bootverbose)
> - printf("random: no preloaded entropy cache\n");
> + size = random_prime_loader_file(RANDOM_CACHED_BOOT_ENTROPY_MODULE);
> + if (bootverbose) {
> + if (size > 0)
> + printf("random: read %zu bytes from preloaded cache\n",
> + size);
> + else
> + printf("random: no preloaded entropy cache\n");
> }
> }
> SYSINIT(random_device_prime, SI_SUB_RANDOM, SI_ORDER_MIDDLE, random_harvestq_prime, NULL);
>
> Modified: head/sys/sys/random.h
> ==============================================================================
> --- head/sys/sys/random.h Fri Nov 22 20:18:07 2019 (r355017)
> +++ head/sys/sys/random.h Fri Nov 22 20:20:37 2019 (r355018)
> @@ -81,7 +81,6 @@ enum random_entropy_source {
> _Static_assert(ENTROPYSOURCE <= 32,
> "hardcoded assumption that values fit in a typical word-sized bitset");
>
> -#define RANDOM_LEGACY_BOOT_ENTROPY_MODULE "/boot/entropy"
> #define RANDOM_CACHED_BOOT_ENTROPY_MODULE "boot_entropy_cache"
>
> extern u_int hc_source_mask;
>
>
>
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