diff options
Diffstat (limited to '0001-random-make-CPU-trust-a-boot-parameter.patch')
| -rw-r--r-- | 0001-random-make-CPU-trust-a-boot-parameter.patch | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/0001-random-make-CPU-trust-a-boot-parameter.patch b/0001-random-make-CPU-trust-a-boot-parameter.patch new file mode 100644 index 000000000..33695fcb4 --- /dev/null +++ b/0001-random-make-CPU-trust-a-boot-parameter.patch @@ -0,0 +1,82 @@ +From 9b25436662d5fb4c66eb527ead53cab15f596ee0 Mon Sep 17 00:00:00 2001 +From: Kees Cook <keescook@chromium.org> +Date: Mon, 27 Aug 2018 14:51:54 -0700 +Subject: [PATCH] random: make CPU trust a boot parameter + +Instead of forcing a distro or other system builder to choose +at build time whether the CPU is trusted for CRNG seeding via +CONFIG_RANDOM_TRUST_CPU, provide a boot-time parameter for end users to +control the choice. The CONFIG will set the default state instead. + +Signed-off-by: Kees Cook <keescook@chromium.org> +Signed-off-by: Theodore Ts'o <tytso@mit.edu> +--- + Documentation/admin-guide/kernel-parameters.txt | 6 ++++++ + drivers/char/Kconfig | 4 ++-- + drivers/char/random.c | 11 ++++++++--- + 3 files changed, 16 insertions(+), 5 deletions(-) + +diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt +index 0c8f7889efa1..227c5c6fa4c1 100644 +--- a/Documentation/admin-guide/kernel-parameters.txt ++++ b/Documentation/admin-guide/kernel-parameters.txt +@@ -3390,6 +3390,12 @@ + ramdisk_size= [RAM] Sizes of RAM disks in kilobytes + 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 + + cec_disable [X86] +diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig +index ce277ee0a28a..40728491f37b 100644 +--- a/drivers/char/Kconfig ++++ b/drivers/char/Kconfig +@@ -566,5 +566,5 @@ config RANDOM_TRUST_CPU + that CPU manufacturer (perhaps with the insistence or mandate + of a Nation State's intelligence or law enforcement agencies) + 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". +diff --git a/drivers/char/random.c b/drivers/char/random.c +index bf5f99fc36f1..c75b6cdf0053 100644 +--- a/drivers/char/random.c ++++ b/drivers/char/random.c +@@ -779,6 +779,13 @@ static struct crng_state **crng_node_pool __read_mostly; + + 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) + { + int i; +@@ -799,12 +806,10 @@ static void crng_initialize(struct crng_state *crng) + } + crng->state[i] ^= rv; + } +-#ifdef CONFIG_RANDOM_TRUST_CPU +- if (arch_init) { ++ if (trust_cpu && arch_init) { + crng_init = 2; + pr_notice("random: crng done (trusting CPU's manufacturer)\n"); + } +-#endif + crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1; + } + +-- +2.17.1 + |