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Use the CPU RNG for entropy (rhbz 1572944)

This commit is contained in:
Laura Abbott 2018-09-13 17:26:33 -07:00
parent 473a8aafe6
commit b1cc6d82ff
22 changed files with 186 additions and 0 deletions
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78
0001-random-add-a-config-option-to-trust-the-CPU-s-hwrng.patch Normal file
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@ -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

82
0001-random-make-CPU-trust-a-boot-parameter.patch Normal file
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@ -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

1
configs/fedora/generic/CONFIG_RANDOM_TRUST_CPU Normal file
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@ -0,0 +1 @@
CONFIG_RANDOM_TRUST_CPU=y

1
kernel-aarch64-debug.config
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@ -4660,6 +4660,7 @@ CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOMIZE_BASE=y
CONFIG_RANDOMIZE_MODULE_REGION_FULL=y
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_RAS_CEC=y
CONFIG_RASPBERRYPI_FIRMWARE=y
CONFIG_RASPBERRYPI_POWER=y

1
kernel-aarch64.config
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@ -4637,6 +4637,7 @@ CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOMIZE_BASE=y
CONFIG_RANDOMIZE_MODULE_REGION_FULL=y
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_RAS_CEC=y
CONFIG_RASPBERRYPI_FIRMWARE=y
CONFIG_RASPBERRYPI_POWER=y

1
kernel-armv7hl-debug.config
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@ -4937,6 +4937,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_RAS_CEC=y
CONFIG_RASPBERRYPI_FIRMWARE=y
CONFIG_RASPBERRYPI_POWER=y

1
kernel-armv7hl-lpae-debug.config
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@ -4661,6 +4661,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_RAS_CEC=y
CONFIG_RASPBERRYPI_FIRMWARE=y
CONFIG_RASPBERRYPI_POWER=y

1
kernel-armv7hl-lpae.config
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@ -4638,6 +4638,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_RAS_CEC=y
CONFIG_RASPBERRYPI_FIRMWARE=y
CONFIG_RASPBERRYPI_POWER=y

1
kernel-armv7hl.config
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@ -4914,6 +4914,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_RAS_CEC=y
CONFIG_RASPBERRYPI_FIRMWARE=y
CONFIG_RASPBERRYPI_POWER=y

1
kernel-i686-PAE.config
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@ -4390,6 +4390,7 @@ CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOMIZE_BASE=y
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

1
kernel-i686-PAEdebug.config
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@ -4414,6 +4414,7 @@ CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOMIZE_BASE=y
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

1
kernel-i686-debug.config
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@ -4414,6 +4414,7 @@ CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOMIZE_BASE=y
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

1
kernel-i686.config
View File

@ -4390,6 +4390,7 @@ CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOMIZE_BASE=y
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

1
kernel-ppc64-debug.config
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@ -4220,6 +4220,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

1
kernel-ppc64.config
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@ -4194,6 +4194,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

1
kernel-ppc64le-debug.config
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@ -4158,6 +4158,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

1
kernel-ppc64le.config
View File

@ -4132,6 +4132,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

1
kernel-s390x-debug.config
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@ -4048,6 +4048,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set
CONFIG_RAW_DRIVER=y

1
kernel-s390x.config
View File

@ -4022,6 +4022,7 @@ CONFIG_RADIO_WL1273=m
CONFIG_RADIO_ZOLTRIX=m
CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set
CONFIG_RAW_DRIVER=y

1
kernel-x86_64-debug.config
View File

@ -4458,6 +4458,7 @@ CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOMIZE_BASE=y
CONFIG_RANDOMIZE_MEMORY=y
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

1
kernel-x86_64.config
View File

@ -4434,6 +4434,7 @@ CONFIG_RAID_ATTRS=m
# CONFIG_RANDOM32_SELFTEST is not set
CONFIG_RANDOMIZE_BASE=y
CONFIG_RANDOMIZE_MEMORY=y
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RAPIDIO is not set
CONFIG_RAS_CEC=y
# CONFIG_RAVE_SP_CORE is not set

7
kernel.spec
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@ -627,6 +627,10 @@ Patch504: xsa270.patch
# rhbz 1627963 1628715
Patch505: HID-fixes.patch
# rhbz 1572944
Patch506: 0001-random-add-a-config-option-to-trust-the-CPU-s-hwrng.patch
Patch507: 0001-random-make-CPU-trust-a-boot-parameter.patch
# END OF PATCH DEFINITIONS
%endif
@ -1876,6 +1880,9 @@ fi
#
#
%changelog
* Thu Sep 13 2018 Laura Abbott <labbott@redhat.com>
- Use the CPU RNG for entropy (rhbz 1572944)
* Thu Sep 13 2018 Laura Abbott <labbott@redhat.com>
- HID fixes (rhbz 1627963 1628715)