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Commit 3243a89d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random 

Pull random driver fix from Ted Ts'o:
 "Fix things so the choice of whether or not to trust RDRAND to
  initialize the CRNG is configurable via the boot option
  random.trust_cpu={on,off}"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: make CPU trust a boot parameter
parents 1d225777 9b254366

Documentation/admin-guide/kernel-parameters.txt

+6 −0
Original line number Original line Diff line number Diff line
@@ -3523,6 +3523,12 @@ 
	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes

	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes

			See Documentation/blockdev/ramdisk.txt.

			See Documentation/blockdev/ramdisk.txt.





	random.trust_cpu={on,off}

			[KNL] Enable or disable trusting the use of the

			CPU's random number generator (if available) to

			fully seed the kernel's CRNG. Default is controlled

			by CONFIG_RANDOM_TRUST_CPU.



	ras=option[,option,...]	[KNL] RAS-specific options

	ras=option[,option,...]	[KNL] RAS-specific options





		cec_disable	[X86]

		cec_disable	[X86]

drivers/char/Kconfig

+2 −2
Original line number Original line Diff line number Diff line
@@ -566,5 +566,5 @@ config RANDOM_TRUST_CPU 
	that CPU manufacturer (perhaps with the insistence or mandate

	that CPU manufacturer (perhaps with the insistence or mandate

	of a Nation State's intelligence or law enforcement agencies)

	of a Nation State's intelligence or law enforcement agencies)

	has not installed a hidden back door to compromise the CPU's

	has not installed a hidden back door to compromise the CPU's

	random number generation facilities.

	random number generation facilities. This can also be configured

	at boot with "random.trust_cpu=on/off".

drivers/char/random.c

+8 −3
Original line number Original line Diff line number Diff line
@@ -779,6 +779,13 @@ static struct crng_state **crng_node_pool __read_mostly; 




static void invalidate_batched_entropy(void);

static void invalidate_batched_entropy(void);





static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);

static int __init parse_trust_cpu(char *arg)

{

	return kstrtobool(arg, &trust_cpu);

}

early_param("random.trust_cpu", parse_trust_cpu);



static void crng_initialize(struct crng_state *crng)

static void crng_initialize(struct crng_state *crng)

{

{

	int		i;

	int		i;
@@ -799,12 +806,10 @@ static void crng_initialize(struct crng_state *crng) 
		}

		}

		crng->state[i] ^= rv;

		crng->state[i] ^= rv;

	}

	}

#ifdef CONFIG_RANDOM_TRUST_CPU

	if (trust_cpu && arch_init) {

	if (arch_init) {

		crng_init = 2;

		crng_init = 2;

		pr_notice("random: crng done (trusting CPU's manufacturer)\n");

		pr_notice("random: crng done (trusting CPU's manufacturer)\n");

	}

	}

#endif

	crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;

	crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;

}

}