subject:"\[PATCH\] KVM\: SVM\: no need to call access_ok\(\) in LAUNCH

Re: [PATCH] KVM: SVM: no need to call access_ok() in LAUNCH_MEASURE command

2018-02-23 Thread Paolo Bonzini

On 23/02/2018 19:36, Brijesh Singh wrote:
> Using the access_ok() to validate the input before issuing the SEV
> command does not buy us anything in this case. If userland is
> giving us a garbage pointer then copy_to_user() will catch it when we try
> to return the measurement.
> 
> Suggested-by: Al Viro 
> Fixes: 0d0736f76347 (KVM: SVM: Add support for KVM_SEV_LAUNCH_MEASURE ...)
> Cc: Paolo Bonzini 
> Cc: "Radim Krčmář" 
> Cc: Borislav Petkov 
> Cc: Tom Lendacky 
> Cc: linux-kernel@vger.kernel.org
> Cc: Joerg Roedel 
> Signed-off-by: Brijesh Singh 
> ---
> 
> We no longer need patch [1]. This patch implements Al Viro's recommendation 
> [2]
> 
> [1] https://marc.info/?l=linux-kernel=151905677729098=2.
> [2] https://marc.info/?l=linux-kernel=151923536116467=2
> 
>  arch/x86/kvm/svm.c | 16 +++-
>  1 file changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index b3e488a74828..ca69d53d7e6d 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -6236,16 +6236,18 @@ static int sev_launch_update_data(struct kvm *kvm, 
> struct kvm_sev_cmd *argp)
>  
>  static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  {
> + void __user *measure = (void __user *)(uintptr_t)argp->data;
>   struct kvm_sev_info *sev = >arch.sev_info;
>   struct sev_data_launch_measure *data;
>   struct kvm_sev_launch_measure params;
> + void __user *p = NULL;
>   void *blob = NULL;
>   int ret;
>  
>   if (!sev_guest(kvm))
>   return -ENOTTY;
>  
> - if (copy_from_user(, (void __user *)(uintptr_t)argp->data, 
> sizeof(params)))
> + if (copy_from_user(, measure, sizeof(params)))
>   return -EFAULT;
>  
>   data = kzalloc(sizeof(*data), GFP_KERNEL);
> @@ -6256,17 +6258,13 @@ static int sev_launch_measure(struct kvm *kvm, struct 
> kvm_sev_cmd *argp)
>   if (!params.len)
>   goto cmd;
>  
> - if (params.uaddr) {
> + p = (void __user *)(uintptr_t)params.uaddr;
> + if (p) {
>   if (params.len > SEV_FW_BLOB_MAX_SIZE) {
>   ret = -EINVAL;
>   goto e_free;
>   }
>  
> - if (!access_ok(VERIFY_WRITE, params.uaddr, params.len)) {
> - ret = -EFAULT;
> - goto e_free;
> - }
> -
>   ret = -ENOMEM;
>   blob = kmalloc(params.len, GFP_KERNEL);
>   if (!blob)
> @@ -6290,13 +6288,13 @@ static int sev_launch_measure(struct kvm *kvm, struct 
> kvm_sev_cmd *argp)
>   goto e_free_blob;
>  
>   if (blob) {
> - if (copy_to_user((void __user *)(uintptr_t)params.uaddr, blob, 
> params.len))
> + if (copy_to_user(p, blob, params.len))
>   ret = -EFAULT;
>   }
>  
>  done:
>   params.len = data->len;
> - if (copy_to_user((void __user *)(uintptr_t)argp->data, , 
> sizeof(params)))
> + if (copy_to_user(measure, , sizeof(params)))
>   ret = -EFAULT;
>  e_free_blob:
>   kfree(blob);
> 

Queued, thanks Brijesh and Al.

Paolo

Re: [PATCH] KVM: SVM: no need to call access_ok() in LAUNCH_MEASURE command

2018-02-23 Thread Paolo Bonzini

On 23/02/2018 19:36, Brijesh Singh wrote:
> Using the access_ok() to validate the input before issuing the SEV
> command does not buy us anything in this case. If userland is
> giving us a garbage pointer then copy_to_user() will catch it when we try
> to return the measurement.
> 
> Suggested-by: Al Viro 
> Fixes: 0d0736f76347 (KVM: SVM: Add support for KVM_SEV_LAUNCH_MEASURE ...)
> Cc: Paolo Bonzini 
> Cc: "Radim Krčmář" 
> Cc: Borislav Petkov 
> Cc: Tom Lendacky 
> Cc: linux-kernel@vger.kernel.org
> Cc: Joerg Roedel 
> Signed-off-by: Brijesh Singh 
> ---
> 
> We no longer need patch [1]. This patch implements Al Viro's recommendation 
> [2]
> 
> [1] https://marc.info/?l=linux-kernel=151905677729098=2.
> [2] https://marc.info/?l=linux-kernel=151923536116467=2
> 
>  arch/x86/kvm/svm.c | 16 +++-
>  1 file changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index b3e488a74828..ca69d53d7e6d 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -6236,16 +6236,18 @@ static int sev_launch_update_data(struct kvm *kvm, 
> struct kvm_sev_cmd *argp)
>  
>  static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  {
> + void __user *measure = (void __user *)(uintptr_t)argp->data;
>   struct kvm_sev_info *sev = >arch.sev_info;
>   struct sev_data_launch_measure *data;
>   struct kvm_sev_launch_measure params;
> + void __user *p = NULL;
>   void *blob = NULL;
>   int ret;
>  
>   if (!sev_guest(kvm))
>   return -ENOTTY;
>  
> - if (copy_from_user(, (void __user *)(uintptr_t)argp->data, 
> sizeof(params)))
> + if (copy_from_user(, measure, sizeof(params)))
>   return -EFAULT;
>  
>   data = kzalloc(sizeof(*data), GFP_KERNEL);
> @@ -6256,17 +6258,13 @@ static int sev_launch_measure(struct kvm *kvm, struct 
> kvm_sev_cmd *argp)
>   if (!params.len)
>   goto cmd;
>  
> - if (params.uaddr) {
> + p = (void __user *)(uintptr_t)params.uaddr;
> + if (p) {
>   if (params.len > SEV_FW_BLOB_MAX_SIZE) {
>   ret = -EINVAL;
>   goto e_free;
>   }
>  
> - if (!access_ok(VERIFY_WRITE, params.uaddr, params.len)) {
> - ret = -EFAULT;
> - goto e_free;
> - }
> -
>   ret = -ENOMEM;
>   blob = kmalloc(params.len, GFP_KERNEL);
>   if (!blob)
> @@ -6290,13 +6288,13 @@ static int sev_launch_measure(struct kvm *kvm, struct 
> kvm_sev_cmd *argp)
>   goto e_free_blob;
>  
>   if (blob) {
> - if (copy_to_user((void __user *)(uintptr_t)params.uaddr, blob, 
> params.len))
> + if (copy_to_user(p, blob, params.len))
>   ret = -EFAULT;
>   }
>  
>  done:
>   params.len = data->len;
> - if (copy_to_user((void __user *)(uintptr_t)argp->data, , 
> sizeof(params)))
> + if (copy_to_user(measure, , sizeof(params)))
>   ret = -EFAULT;
>  e_free_blob:
>   kfree(blob);
> 

Queued, thanks Brijesh and Al.

Paolo

[PATCH] KVM: SVM: no need to call access_ok() in LAUNCH_MEASURE command

2018-02-23 Thread Brijesh Singh

Using the access_ok() to validate the input before issuing the SEV
command does not buy us anything in this case. If userland is
giving us a garbage pointer then copy_to_user() will catch it when we try
to return the measurement.

Suggested-by: Al Viro 
Fixes: 0d0736f76347 (KVM: SVM: Add support for KVM_SEV_LAUNCH_MEASURE ...)
Cc: Paolo Bonzini 
Cc: "Radim Krčmář" 
Cc: Borislav Petkov 
Cc: Tom Lendacky 
Cc: linux-kernel@vger.kernel.org
Cc: Joerg Roedel 
Signed-off-by: Brijesh Singh 
---

We no longer need patch [1]. This patch implements Al Viro's recommendation [2]

[1] https://marc.info/?l=linux-kernel=151905677729098=2.
[2] https://marc.info/?l=linux-kernel=151923536116467=2

 arch/x86/kvm/svm.c | 16 +++-
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b3e488a74828..ca69d53d7e6d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6236,16 +6236,18 @@ static int sev_launch_update_data(struct kvm *kvm, 
struct kvm_sev_cmd *argp)
 
 static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp)
 {
+   void __user *measure = (void __user *)(uintptr_t)argp->data;
struct kvm_sev_info *sev = >arch.sev_info;
struct sev_data_launch_measure *data;
struct kvm_sev_launch_measure params;
+   void __user *p = NULL;
void *blob = NULL;
int ret;
 
if (!sev_guest(kvm))
return -ENOTTY;
 
-   if (copy_from_user(, (void __user *)(uintptr_t)argp->data, 
sizeof(params)))
+   if (copy_from_user(, measure, sizeof(params)))
return -EFAULT;
 
data = kzalloc(sizeof(*data), GFP_KERNEL);
@@ -6256,17 +6258,13 @@ static int sev_launch_measure(struct kvm *kvm, struct 
kvm_sev_cmd *argp)
if (!params.len)
goto cmd;
 
-   if (params.uaddr) {
+   p = (void __user *)(uintptr_t)params.uaddr;
+   if (p) {
if (params.len > SEV_FW_BLOB_MAX_SIZE) {
ret = -EINVAL;
goto e_free;
}
 
-   if (!access_ok(VERIFY_WRITE, params.uaddr, params.len)) {
-   ret = -EFAULT;
-   goto e_free;
-   }
-
ret = -ENOMEM;
blob = kmalloc(params.len, GFP_KERNEL);
if (!blob)
@@ -6290,13 +6288,13 @@ static int sev_launch_measure(struct kvm *kvm, struct 
kvm_sev_cmd *argp)
goto e_free_blob;
 
if (blob) {
-   if (copy_to_user((void __user *)(uintptr_t)params.uaddr, blob, 
params.len))
+   if (copy_to_user(p, blob, params.len))
ret = -EFAULT;
}
 
 done:
params.len = data->len;
-   if (copy_to_user((void __user *)(uintptr_t)argp->data, , 
sizeof(params)))
+   if (copy_to_user(measure, , sizeof(params)))
ret = -EFAULT;
 e_free_blob:
kfree(blob);
-- 
2.14.3

[PATCH] KVM: SVM: no need to call access_ok() in LAUNCH_MEASURE command

2018-02-23 Thread Brijesh Singh

Using the access_ok() to validate the input before issuing the SEV
command does not buy us anything in this case. If userland is
giving us a garbage pointer then copy_to_user() will catch it when we try
to return the measurement.

Suggested-by: Al Viro 
Fixes: 0d0736f76347 (KVM: SVM: Add support for KVM_SEV_LAUNCH_MEASURE ...)
Cc: Paolo Bonzini 
Cc: "Radim Krčmář" 
Cc: Borislav Petkov 
Cc: Tom Lendacky 
Cc: linux-kernel@vger.kernel.org
Cc: Joerg Roedel 
Signed-off-by: Brijesh Singh 
---

We no longer need patch [1]. This patch implements Al Viro's recommendation [2]

[1] https://marc.info/?l=linux-kernel=151905677729098=2.
[2] https://marc.info/?l=linux-kernel=151923536116467=2

 arch/x86/kvm/svm.c | 16 +++-
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b3e488a74828..ca69d53d7e6d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6236,16 +6236,18 @@ static int sev_launch_update_data(struct kvm *kvm, 
struct kvm_sev_cmd *argp)
 
 static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp)
 {
+   void __user *measure = (void __user *)(uintptr_t)argp->data;
struct kvm_sev_info *sev = >arch.sev_info;
struct sev_data_launch_measure *data;
struct kvm_sev_launch_measure params;
+   void __user *p = NULL;
void *blob = NULL;
int ret;
 
if (!sev_guest(kvm))
return -ENOTTY;
 
-   if (copy_from_user(, (void __user *)(uintptr_t)argp->data, 
sizeof(params)))
+   if (copy_from_user(, measure, sizeof(params)))
return -EFAULT;
 
data = kzalloc(sizeof(*data), GFP_KERNEL);
@@ -6256,17 +6258,13 @@ static int sev_launch_measure(struct kvm *kvm, struct 
kvm_sev_cmd *argp)
if (!params.len)
goto cmd;
 
-   if (params.uaddr) {
+   p = (void __user *)(uintptr_t)params.uaddr;
+   if (p) {
if (params.len > SEV_FW_BLOB_MAX_SIZE) {
ret = -EINVAL;
goto e_free;
}
 
-   if (!access_ok(VERIFY_WRITE, params.uaddr, params.len)) {
-   ret = -EFAULT;
-   goto e_free;
-   }
-
ret = -ENOMEM;
blob = kmalloc(params.len, GFP_KERNEL);
if (!blob)
@@ -6290,13 +6288,13 @@ static int sev_launch_measure(struct kvm *kvm, struct 
kvm_sev_cmd *argp)
goto e_free_blob;
 
if (blob) {
-   if (copy_to_user((void __user *)(uintptr_t)params.uaddr, blob, 
params.len))
+   if (copy_to_user(p, blob, params.len))
ret = -EFAULT;
}
 
 done:
params.len = data->len;
-   if (copy_to_user((void __user *)(uintptr_t)argp->data, , 
sizeof(params)))
+   if (copy_to_user(measure, , sizeof(params)))
ret = -EFAULT;
 e_free_blob:
kfree(blob);
-- 
2.14.3

Re: [PATCH] KVM: SVM: no need to call access_ok() in LAUNCH_MEASURE command

Re: [PATCH] KVM: SVM: no need to call access_ok() in LAUNCH_MEASURE command

[PATCH] KVM: SVM: no need to call access_ok() in LAUNCH_MEASURE command

[PATCH] KVM: SVM: no need to call access_ok() in LAUNCH_MEASURE command

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