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authorLinus Torvalds <torvalds@linux-foundation.org>2022-04-01 00:51:34 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-04-01 00:51:34 +0300
commit478f74a3d8085076dfcb481aa9361b808a6aae94 (patch)
tree9392ad6d7fe8dce797c3ea16fcec3c453348938d
parent354b8bf222ee15bf9aac3d870ba8e0880dd9bc8d (diff)
parent1754abb3e7583c570666fa1e1ee5b317e88c89a0 (diff)
downloadlinux-478f74a3d8085076dfcb481aa9361b808a6aae94.tar.xz
Merge tag 'random-5.18-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator fixes from Jason Donenfeld: - If a hardware random number generator passes a sufficiently large chunk of entropy to random.c during early boot, we now skip the "fast_init" business and let it initialize the RNG. This makes CONFIG_RANDOM_TRUST_BOOTLOADER=y actually useful. - We already have the command line `random.trust_cpu=0/1` option for RDRAND, which let distros enable CONFIG_RANDOM_TRUST_CPU=y while placating concerns of more paranoid users. Now we add `random.trust_bootloader=0/1` so that distros can similarly enable CONFIG_RANDOM_TRUST_BOOTLOADER=y. - Re-add a comment that got removed by accident in the recent revert. - Add the spec-compliant ACPI CID for vmgenid, which Microsoft added to the vmgenid spec at Ard's request during earlier review. - Restore build-time randomness via the latent entropy plugin, which was lost when we transitioned to using a hash function. * tag 'random-5.18-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: random: mix build-time latent entropy into pool at init virt: vmgenid: recognize new CID added by Hyper-V random: re-add removed comment about get_random_{u32,u64} reseeding random: treat bootloader trust toggle the same way as cpu trust toggle random: skip fast_init if hwrng provides large chunk of entropy
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt6
-rw-r--r--drivers/char/Kconfig3
-rw-r--r--drivers/char/random.c22
-rw-r--r--drivers/virt/vmgenid.c1
4 files changed, 26 insertions, 6 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b7ccaa2ea867..3f1cc5e317ed 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4427,6 +4427,12 @@
fully seed the kernel's CRNG. Default is controlled
by CONFIG_RANDOM_TRUST_CPU.
+ random.trust_bootloader={on,off}
+ [KNL] Enable or disable trusting the use of a
+ seed passed by the bootloader (if available) to
+ fully seed the kernel's CRNG. Default is controlled
+ by CONFIG_RANDOM_TRUST_BOOTLOADER.
+
randomize_kstack_offset=
[KNL] Enable or disable kernel stack offset
randomization, which provides roughly 5 bits of
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 740811893c57..55f48375e3fe 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -449,6 +449,7 @@ config RANDOM_TRUST_BOOTLOADER
device randomness. Say Y here to assume the entropy provided by the
booloader is trustworthy so it will be added to the kernel's entropy
pool. Otherwise, say N here so it will be regarded as device input that
- only mixes the entropy pool.
+ only mixes the entropy pool. This can also be configured at boot with
+ "random.trust_bootloader=on/off".
endmenu
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 66ce7c03a142..1d8242969751 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -224,9 +224,10 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller, void
*
* These interfaces will return the requested number of random bytes
* into the given buffer or as a return value. This is equivalent to
- * a read from /dev/urandom. The integer family of functions may be
- * higher performance for one-off random integers, because they do a
- * bit of buffering.
+ * a read from /dev/urandom. The u32, u64, int, and long family of
+ * functions may be higher performance for one-off random integers,
+ * because they do a bit of buffering and do not invoke reseeding
+ * until the buffer is emptied.
*
*********************************************************************/
@@ -948,11 +949,17 @@ static bool drain_entropy(void *buf, size_t nbytes, bool force)
**********************************************************************/
static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
+static bool trust_bootloader __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER);
static int __init parse_trust_cpu(char *arg)
{
return kstrtobool(arg, &trust_cpu);
}
+static int __init parse_trust_bootloader(char *arg)
+{
+ return kstrtobool(arg, &trust_bootloader);
+}
early_param("random.trust_cpu", parse_trust_cpu);
+early_param("random.trust_bootloader", parse_trust_bootloader);
/*
* The first collection of entropy occurs at system boot while interrupts
@@ -968,6 +975,11 @@ int __init rand_initialize(void)
bool arch_init = true;
unsigned long rv;
+#if defined(LATENT_ENTROPY_PLUGIN)
+ static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy;
+ _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed));
+#endif
+
for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) {
if (!arch_get_random_seed_long_early(&rv) &&
!arch_get_random_long_early(&rv)) {
@@ -1128,7 +1140,7 @@ void rand_initialize_disk(struct gendisk *disk)
void add_hwgenerator_randomness(const void *buffer, size_t count,
size_t entropy)
{
- if (unlikely(crng_init == 0)) {
+ if (unlikely(crng_init == 0 && entropy < POOL_MIN_BITS)) {
size_t ret = crng_pre_init_inject(buffer, count, true);
mix_pool_bytes(buffer, ret);
count -= ret;
@@ -1160,7 +1172,7 @@ EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
*/
void add_bootloader_randomness(const void *buf, size_t size)
{
- if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER))
+ if (trust_bootloader)
add_hwgenerator_randomness(buf, size, size * 8);
else
add_device_randomness(buf, size);
diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
index 0ae1a39f2e28..a1c467a0e9f7 100644
--- a/drivers/virt/vmgenid.c
+++ b/drivers/virt/vmgenid.c
@@ -78,6 +78,7 @@ static void vmgenid_notify(struct acpi_device *device, u32 event)
}
static const struct acpi_device_id vmgenid_ids[] = {
+ { "VMGENCTR", 0 },
{ "VM_GEN_COUNTER", 0 },
{ }
};