diff options
Diffstat (limited to '0001-random-add-a-config-option-to-trust-the-CPU-s-hwrng.patch')
| -rw-r--r-- | 0001-random-add-a-config-option-to-trust-the-CPU-s-hwrng.patch | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/0001-random-add-a-config-option-to-trust-the-CPU-s-hwrng.patch b/0001-random-add-a-config-option-to-trust-the-CPU-s-hwrng.patch new file mode 100644 index 000000000..8a2f68f82 --- /dev/null +++ b/0001-random-add-a-config-option-to-trust-the-CPU-s-hwrng.patch @@ -0,0 +1,78 @@ +From 39a8883a2b989d1d21bd8dd99f5557f0c5e89694 Mon Sep 17 00:00:00 2001 +From: Theodore Ts'o <tytso@mit.edu> +Date: Tue, 17 Jul 2018 18:24:27 -0400 +Subject: [PATCH] random: add a config option to trust the CPU's hwrng + +This gives the user building their own kernel (or a Linux +distribution) the option of deciding whether or not to trust the CPU's +hardware random number generator (e.g., RDRAND for x86 CPU's) as being +correctly implemented and not having a back door introduced (perhaps +courtesy of a Nation State's law enforcement or intelligence +agencies). + +This will prevent getrandom(2) from blocking, if there is a +willingness to trust the CPU manufacturer. + +Signed-off-by: Theodore Ts'o <tytso@mit.edu> +--- + drivers/char/Kconfig | 14 ++++++++++++++ + drivers/char/random.c | 11 ++++++++++- + 2 files changed, 24 insertions(+), 1 deletion(-) + +diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig +index 212f447938ae..ce277ee0a28a 100644 +--- a/drivers/char/Kconfig ++++ b/drivers/char/Kconfig +@@ -554,3 +554,17 @@ config ADI + + endmenu + ++config RANDOM_TRUST_CPU ++ bool "Trust the CPU manufacturer to initialize Linux's CRNG" ++ depends on X86 || S390 || PPC ++ default n ++ help ++ Assume that CPU manufacturer (e.g., Intel or AMD for RDSEED or ++ RDRAND, IBM for the S390 and Power PC architectures) is trustworthy ++ for the purposes of initializing Linux's CRNG. Since this is not ++ something that can be independently audited, this amounts to trusting ++ 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. ++ +diff --git a/drivers/char/random.c b/drivers/char/random.c +index 34ddfd57419b..f4013b8a711b 100644 +--- a/drivers/char/random.c ++++ b/drivers/char/random.c +@@ -782,6 +782,7 @@ static void invalidate_batched_entropy(void); + static void crng_initialize(struct crng_state *crng) + { + int i; ++ int arch_init = 1; + unsigned long rv; + + memcpy(&crng->state[0], "expand 32-byte k", 16); +@@ -792,10 +793,18 @@ static void crng_initialize(struct crng_state *crng) + _get_random_bytes(&crng->state[4], sizeof(__u32) * 12); + for (i = 4; i < 16; i++) { + if (!arch_get_random_seed_long(&rv) && +- !arch_get_random_long(&rv)) ++ !arch_get_random_long(&rv)) { + rv = random_get_entropy(); ++ arch_init = 0; ++ } + crng->state[i] ^= rv; + } ++#ifdef CONFIG_RANDOM_TRUST_CPU ++ if (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 + |