subject:"\[PATCH v5 4\/5\] x86,random,kvm\: Use KVM_GET_RNG_SEED in arch_get_rng

Re: [PATCH v5 4/5] x86,random,kvm: Use KVM_GET_RNG_SEED in arch_get_rng_seed

2014-07-31 Thread Paolo Bonzini

Il 24/07/2014 06:57, Andy Lutomirski ha scritto:
> This is a straightforward implementation: for each bit of internal
> RNG state, request one bit from KVM_GET_RNG_SEED.  This is done even
> if RDSEED/RDRAND worked, since KVM_GET_RNG_SEED is likely to provide
> cryptographically secure output even if the CPU's RNG is weak or
> compromised.
> 
> Signed-off-by: Andy Lutomirski 
> ---
>  arch/x86/Kconfig |  4 
>  arch/x86/include/asm/kvm_guest.h |  9 +
>  arch/x86/kernel/archrandom.c | 25 -
>  arch/x86/kernel/kvm.c| 10 ++
>  4 files changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index a8f749e..adfa09c 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -593,6 +593,7 @@ config KVM_GUEST
>   bool "KVM Guest support (including kvmclock)"
>   depends on PARAVIRT
>   select PARAVIRT_CLOCK
> + select ARCH_RANDOM
>   default y
>   ---help---
> This option enables various optimizations for running under the KVM
> @@ -1507,6 +1508,9 @@ config ARCH_RANDOM
> If supported, this is a high bandwidth, cryptographically
> secure hardware random number generator.
>  
> +   This also enables paravirt RNGs such as KVM's if the relevant
> +   PV guest support is enabled.
> +
>  config X86_SMAP
>   def_bool y
>   prompt "Supervisor Mode Access Prevention" if EXPERT
> diff --git a/arch/x86/include/asm/kvm_guest.h 
> b/arch/x86/include/asm/kvm_guest.h
> index a92b176..8c4dbd5 100644
> --- a/arch/x86/include/asm/kvm_guest.h
> +++ b/arch/x86/include/asm/kvm_guest.h
> @@ -3,4 +3,13 @@
>  
>  int kvm_setup_vsyscall_timeinfo(void);
>  
> +#if defined(CONFIG_KVM_GUEST) && defined(CONFIG_ARCH_RANDOM)
> +extern bool kvm_get_rng_seed(u64 *rv);
> +#else
> +static inline bool kvm_get_rng_seed(u64 *rv)
> +{
> + return false;
> +}
> +#endif
> +
>  #endif /* _ASM_X86_KVM_GUEST_H */
> diff --git a/arch/x86/kernel/archrandom.c b/arch/x86/kernel/archrandom.c
> index 47d13b0..8c8d021 100644
> --- a/arch/x86/kernel/archrandom.c
> +++ b/arch/x86/kernel/archrandom.c
> @@ -15,6 +15,7 @@
>   */
>  
>  #include 
> +#include 
>  
>  void arch_get_rng_seed(void *ctx,
>  void (*seed)(void *ctx, u32 data),
> @@ -22,7 +23,7 @@ void arch_get_rng_seed(void *ctx,
>  const char *log_prefix)
>  {
>   int i;
> - int rdseed_bits = 0, rdrand_bits = 0;
> + int rdseed_bits = 0, rdrand_bits = 0, kvm_bits = 0;
>   char buf[128] = "";
>   char *msgptr = buf;
>  
> @@ -42,10 +43,32 @@ void arch_get_rng_seed(void *ctx,
>  #endif
>   }
>  
> + /*
> +  * Use KVM_GET_RNG_SEED regardless of whether the CPU RNG
> +  * worked, since it incorporates entropy unavailable to the CPU,
> +  * and we shouldn't trust the hardware RNG more than we need to.
> +  * We request enough bits for the entire internal RNG state,
> +  * because there's no good reason not to.
> +  */
> + for (i = 0; i < bits_per_source; i += 64) {
> + u64 rv;
> +
> + if (kvm_get_rng_seed()) {
> + seed(ctx, (u32)rv);
> + seed(ctx, (u32)(rv >> 32));
> + kvm_bits += 8 * sizeof(rv);
> + } else {
> + break;  /* If it fails once, it will keep failing. */
> + }
> + }
> +
>   if (rdseed_bits)
>   msgptr += sprintf(msgptr, ", %d bits from RDSEED", rdseed_bits);
>   if (rdrand_bits)
>   msgptr += sprintf(msgptr, ", %d bits from RDRAND", rdrand_bits);
> + if (kvm_bits)
> + msgptr += sprintf(msgptr, ", %d bits from KVM_GET_RNG_BITS",
> +   kvm_bits);
>   if (buf[0])
>   pr_info("%s with %s\n", log_prefix, buf + 2);
>  }
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 3dd8e2c..bd8783a 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -416,6 +416,16 @@ void kvm_disable_steal_time(void)
>   wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
>  }
>  
> +bool kvm_get_rng_seed(u64 *v)
> +{
> + /*
> +  * Allow migration from a hypervisor with the GET_RNG_SEED
> +  * feature to a hypervisor without it.
> +  */
> + return (kvm_para_has_feature(KVM_FEATURE_GET_RNG_SEED) &&
> + rdmsrl_safe(MSR_KVM_GET_RNG_SEED, v) == 0);
> +}
> +
>  #ifdef CONFIG_SMP
>  static void __init kvm_smp_prepare_boot_cpu(void)
>  {
> 

Acked-by: Paolo Bonzini 
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Re: [PATCH v5 4/5] x86,random,kvm: Use KVM_GET_RNG_SEED in arch_get_rng_seed

2014-07-31 Thread Paolo Bonzini

Il 24/07/2014 06:57, Andy Lutomirski ha scritto:
 This is a straightforward implementation: for each bit of internal
 RNG state, request one bit from KVM_GET_RNG_SEED.  This is done even
 if RDSEED/RDRAND worked, since KVM_GET_RNG_SEED is likely to provide
 cryptographically secure output even if the CPU's RNG is weak or
 compromised.
 
 Signed-off-by: Andy Lutomirski l...@amacapital.net
 ---
  arch/x86/Kconfig |  4 
  arch/x86/include/asm/kvm_guest.h |  9 +
  arch/x86/kernel/archrandom.c | 25 -
  arch/x86/kernel/kvm.c| 10 ++
  4 files changed, 47 insertions(+), 1 deletion(-)
 
 diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
 index a8f749e..adfa09c 100644
 --- a/arch/x86/Kconfig
 +++ b/arch/x86/Kconfig
 @@ -593,6 +593,7 @@ config KVM_GUEST
   bool KVM Guest support (including kvmclock)
   depends on PARAVIRT
   select PARAVIRT_CLOCK
 + select ARCH_RANDOM
   default y
   ---help---
 This option enables various optimizations for running under the KVM
 @@ -1507,6 +1508,9 @@ config ARCH_RANDOM
 If supported, this is a high bandwidth, cryptographically
 secure hardware random number generator.
  
 +   This also enables paravirt RNGs such as KVM's if the relevant
 +   PV guest support is enabled.
 +
  config X86_SMAP
   def_bool y
   prompt Supervisor Mode Access Prevention if EXPERT
 diff --git a/arch/x86/include/asm/kvm_guest.h 
 b/arch/x86/include/asm/kvm_guest.h
 index a92b176..8c4dbd5 100644
 --- a/arch/x86/include/asm/kvm_guest.h
 +++ b/arch/x86/include/asm/kvm_guest.h
 @@ -3,4 +3,13 @@
  
  int kvm_setup_vsyscall_timeinfo(void);
  
 +#if defined(CONFIG_KVM_GUEST)  defined(CONFIG_ARCH_RANDOM)
 +extern bool kvm_get_rng_seed(u64 *rv);
 +#else
 +static inline bool kvm_get_rng_seed(u64 *rv)
 +{
 + return false;
 +}
 +#endif
 +
  #endif /* _ASM_X86_KVM_GUEST_H */
 diff --git a/arch/x86/kernel/archrandom.c b/arch/x86/kernel/archrandom.c
 index 47d13b0..8c8d021 100644
 --- a/arch/x86/kernel/archrandom.c
 +++ b/arch/x86/kernel/archrandom.c
 @@ -15,6 +15,7 @@
   */
  
  #include asm/archrandom.h
 +#include asm/kvm_guest.h
  
  void arch_get_rng_seed(void *ctx,
  void (*seed)(void *ctx, u32 data),
 @@ -22,7 +23,7 @@ void arch_get_rng_seed(void *ctx,
  const char *log_prefix)
  {
   int i;
 - int rdseed_bits = 0, rdrand_bits = 0;
 + int rdseed_bits = 0, rdrand_bits = 0, kvm_bits = 0;
   char buf[128] = ;
   char *msgptr = buf;
  
 @@ -42,10 +43,32 @@ void arch_get_rng_seed(void *ctx,
  #endif
   }
  
 + /*
 +  * Use KVM_GET_RNG_SEED regardless of whether the CPU RNG
 +  * worked, since it incorporates entropy unavailable to the CPU,
 +  * and we shouldn't trust the hardware RNG more than we need to.
 +  * We request enough bits for the entire internal RNG state,
 +  * because there's no good reason not to.
 +  */
 + for (i = 0; i  bits_per_source; i += 64) {
 + u64 rv;
 +
 + if (kvm_get_rng_seed(rv)) {
 + seed(ctx, (u32)rv);
 + seed(ctx, (u32)(rv  32));
 + kvm_bits += 8 * sizeof(rv);
 + } else {
 + break;  /* If it fails once, it will keep failing. */
 + }
 + }
 +
   if (rdseed_bits)
   msgptr += sprintf(msgptr, , %d bits from RDSEED, rdseed_bits);
   if (rdrand_bits)
   msgptr += sprintf(msgptr, , %d bits from RDRAND, rdrand_bits);
 + if (kvm_bits)
 + msgptr += sprintf(msgptr, , %d bits from KVM_GET_RNG_BITS,
 +   kvm_bits);
   if (buf[0])
   pr_info(%s with %s\n, log_prefix, buf + 2);
  }
 diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
 index 3dd8e2c..bd8783a 100644
 --- a/arch/x86/kernel/kvm.c
 +++ b/arch/x86/kernel/kvm.c
 @@ -416,6 +416,16 @@ void kvm_disable_steal_time(void)
   wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
  }
  
 +bool kvm_get_rng_seed(u64 *v)
 +{
 + /*
 +  * Allow migration from a hypervisor with the GET_RNG_SEED
 +  * feature to a hypervisor without it.
 +  */
 + return (kvm_para_has_feature(KVM_FEATURE_GET_RNG_SEED) 
 + rdmsrl_safe(MSR_KVM_GET_RNG_SEED, v) == 0);
 +}
 +
  #ifdef CONFIG_SMP
  static void __init kvm_smp_prepare_boot_cpu(void)
  {
 

Acked-by: Paolo Bonzini pbonz...@redhat.com
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[PATCH v5 4/5] x86,random,kvm: Use KVM_GET_RNG_SEED in arch_get_rng_seed

2014-07-23 Thread Andy Lutomirski

This is a straightforward implementation: for each bit of internal
RNG state, request one bit from KVM_GET_RNG_SEED.  This is done even
if RDSEED/RDRAND worked, since KVM_GET_RNG_SEED is likely to provide
cryptographically secure output even if the CPU's RNG is weak or
compromised.

Signed-off-by: Andy Lutomirski 
---
 arch/x86/Kconfig |  4 
 arch/x86/include/asm/kvm_guest.h |  9 +
 arch/x86/kernel/archrandom.c | 25 -
 arch/x86/kernel/kvm.c| 10 ++
 4 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a8f749e..adfa09c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -593,6 +593,7 @@ config KVM_GUEST
bool "KVM Guest support (including kvmclock)"
depends on PARAVIRT
select PARAVIRT_CLOCK
+   select ARCH_RANDOM
default y
---help---
  This option enables various optimizations for running under the KVM
@@ -1507,6 +1508,9 @@ config ARCH_RANDOM
  If supported, this is a high bandwidth, cryptographically
  secure hardware random number generator.
 
+ This also enables paravirt RNGs such as KVM's if the relevant
+ PV guest support is enabled.
+
 config X86_SMAP
def_bool y
prompt "Supervisor Mode Access Prevention" if EXPERT
diff --git a/arch/x86/include/asm/kvm_guest.h b/arch/x86/include/asm/kvm_guest.h
index a92b176..8c4dbd5 100644
--- a/arch/x86/include/asm/kvm_guest.h
+++ b/arch/x86/include/asm/kvm_guest.h
@@ -3,4 +3,13 @@
 
 int kvm_setup_vsyscall_timeinfo(void);
 
+#if defined(CONFIG_KVM_GUEST) && defined(CONFIG_ARCH_RANDOM)
+extern bool kvm_get_rng_seed(u64 *rv);
+#else
+static inline bool kvm_get_rng_seed(u64 *rv)
+{
+   return false;
+}
+#endif
+
 #endif /* _ASM_X86_KVM_GUEST_H */
diff --git a/arch/x86/kernel/archrandom.c b/arch/x86/kernel/archrandom.c
index 47d13b0..8c8d021 100644
--- a/arch/x86/kernel/archrandom.c
+++ b/arch/x86/kernel/archrandom.c
@@ -15,6 +15,7 @@
  */
 
 #include 
+#include 
 
 void arch_get_rng_seed(void *ctx,
   void (*seed)(void *ctx, u32 data),
@@ -22,7 +23,7 @@ void arch_get_rng_seed(void *ctx,
   const char *log_prefix)
 {
int i;
-   int rdseed_bits = 0, rdrand_bits = 0;
+   int rdseed_bits = 0, rdrand_bits = 0, kvm_bits = 0;
char buf[128] = "";
char *msgptr = buf;
 
@@ -42,10 +43,32 @@ void arch_get_rng_seed(void *ctx,
 #endif
}
 
+   /*
+* Use KVM_GET_RNG_SEED regardless of whether the CPU RNG
+* worked, since it incorporates entropy unavailable to the CPU,
+* and we shouldn't trust the hardware RNG more than we need to.
+* We request enough bits for the entire internal RNG state,
+* because there's no good reason not to.
+*/
+   for (i = 0; i < bits_per_source; i += 64) {
+   u64 rv;
+
+   if (kvm_get_rng_seed()) {
+   seed(ctx, (u32)rv);
+   seed(ctx, (u32)(rv >> 32));
+   kvm_bits += 8 * sizeof(rv);
+   } else {
+   break;  /* If it fails once, it will keep failing. */
+   }
+   }
+
if (rdseed_bits)
msgptr += sprintf(msgptr, ", %d bits from RDSEED", rdseed_bits);
if (rdrand_bits)
msgptr += sprintf(msgptr, ", %d bits from RDRAND", rdrand_bits);
+   if (kvm_bits)
+   msgptr += sprintf(msgptr, ", %d bits from KVM_GET_RNG_BITS",
+ kvm_bits);
if (buf[0])
pr_info("%s with %s\n", log_prefix, buf + 2);
 }
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 3dd8e2c..bd8783a 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -416,6 +416,16 @@ void kvm_disable_steal_time(void)
wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 }
 
+bool kvm_get_rng_seed(u64 *v)
+{
+   /*
+* Allow migration from a hypervisor with the GET_RNG_SEED
+* feature to a hypervisor without it.
+*/
+   return (kvm_para_has_feature(KVM_FEATURE_GET_RNG_SEED) &&
+   rdmsrl_safe(MSR_KVM_GET_RNG_SEED, v) == 0);
+}
+
 #ifdef CONFIG_SMP
 static void __init kvm_smp_prepare_boot_cpu(void)
 {
-- 
1.9.3

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[PATCH v5 4/5] x86,random,kvm: Use KVM_GET_RNG_SEED in arch_get_rng_seed

2014-07-23 Thread Andy Lutomirski

This is a straightforward implementation: for each bit of internal
RNG state, request one bit from KVM_GET_RNG_SEED.  This is done even
if RDSEED/RDRAND worked, since KVM_GET_RNG_SEED is likely to provide
cryptographically secure output even if the CPU's RNG is weak or
compromised.

Signed-off-by: Andy Lutomirski l...@amacapital.net
---
 arch/x86/Kconfig |  4 
 arch/x86/include/asm/kvm_guest.h |  9 +
 arch/x86/kernel/archrandom.c | 25 -
 arch/x86/kernel/kvm.c| 10 ++
 4 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a8f749e..adfa09c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -593,6 +593,7 @@ config KVM_GUEST
bool KVM Guest support (including kvmclock)
depends on PARAVIRT
select PARAVIRT_CLOCK
+   select ARCH_RANDOM
default y
---help---
  This option enables various optimizations for running under the KVM
@@ -1507,6 +1508,9 @@ config ARCH_RANDOM
  If supported, this is a high bandwidth, cryptographically
  secure hardware random number generator.
 
+ This also enables paravirt RNGs such as KVM's if the relevant
+ PV guest support is enabled.
+
 config X86_SMAP
def_bool y
prompt Supervisor Mode Access Prevention if EXPERT
diff --git a/arch/x86/include/asm/kvm_guest.h b/arch/x86/include/asm/kvm_guest.h
index a92b176..8c4dbd5 100644
--- a/arch/x86/include/asm/kvm_guest.h
+++ b/arch/x86/include/asm/kvm_guest.h
@@ -3,4 +3,13 @@
 
 int kvm_setup_vsyscall_timeinfo(void);
 
+#if defined(CONFIG_KVM_GUEST)  defined(CONFIG_ARCH_RANDOM)
+extern bool kvm_get_rng_seed(u64 *rv);
+#else
+static inline bool kvm_get_rng_seed(u64 *rv)
+{
+   return false;
+}
+#endif
+
 #endif /* _ASM_X86_KVM_GUEST_H */
diff --git a/arch/x86/kernel/archrandom.c b/arch/x86/kernel/archrandom.c
index 47d13b0..8c8d021 100644
--- a/arch/x86/kernel/archrandom.c
+++ b/arch/x86/kernel/archrandom.c
@@ -15,6 +15,7 @@
  */
 
 #include asm/archrandom.h
+#include asm/kvm_guest.h
 
 void arch_get_rng_seed(void *ctx,
   void (*seed)(void *ctx, u32 data),
@@ -22,7 +23,7 @@ void arch_get_rng_seed(void *ctx,
   const char *log_prefix)
 {
int i;
-   int rdseed_bits = 0, rdrand_bits = 0;
+   int rdseed_bits = 0, rdrand_bits = 0, kvm_bits = 0;
char buf[128] = ;
char *msgptr = buf;
 
@@ -42,10 +43,32 @@ void arch_get_rng_seed(void *ctx,
 #endif
}
 
+   /*
+* Use KVM_GET_RNG_SEED regardless of whether the CPU RNG
+* worked, since it incorporates entropy unavailable to the CPU,
+* and we shouldn't trust the hardware RNG more than we need to.
+* We request enough bits for the entire internal RNG state,
+* because there's no good reason not to.
+*/
+   for (i = 0; i  bits_per_source; i += 64) {
+   u64 rv;
+
+   if (kvm_get_rng_seed(rv)) {
+   seed(ctx, (u32)rv);
+   seed(ctx, (u32)(rv  32));
+   kvm_bits += 8 * sizeof(rv);
+   } else {
+   break;  /* If it fails once, it will keep failing. */
+   }
+   }
+
if (rdseed_bits)
msgptr += sprintf(msgptr, , %d bits from RDSEED, rdseed_bits);
if (rdrand_bits)
msgptr += sprintf(msgptr, , %d bits from RDRAND, rdrand_bits);
+   if (kvm_bits)
+   msgptr += sprintf(msgptr, , %d bits from KVM_GET_RNG_BITS,
+ kvm_bits);
if (buf[0])
pr_info(%s with %s\n, log_prefix, buf + 2);
 }
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 3dd8e2c..bd8783a 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -416,6 +416,16 @@ void kvm_disable_steal_time(void)
wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 }
 
+bool kvm_get_rng_seed(u64 *v)
+{
+   /*
+* Allow migration from a hypervisor with the GET_RNG_SEED
+* feature to a hypervisor without it.
+*/
+   return (kvm_para_has_feature(KVM_FEATURE_GET_RNG_SEED) 
+   rdmsrl_safe(MSR_KVM_GET_RNG_SEED, v) == 0);
+}
+
 #ifdef CONFIG_SMP
 static void __init kvm_smp_prepare_boot_cpu(void)
 {
-- 
1.9.3

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Re: [PATCH v5 4/5] x86,random,kvm: Use KVM_GET_RNG_SEED in arch_get_rng_seed

Re: [PATCH v5 4/5] x86,random,kvm: Use KVM_GET_RNG_SEED in arch_get_rng_seed

[PATCH v5 4/5] x86,random,kvm: Use KVM_GET_RNG_SEED in arch_get_rng_seed

[PATCH v5 4/5] x86,random,kvm: Use KVM_GET_RNG_SEED in arch_get_rng_seed

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