Re: [RFC PATCH v2 10/20] x86: Insure that memory areas are encrypted when possible

[Tom Lendacky]

On 09/12/2016 11:33 AM, Borislav Petkov wrote:
> On Mon, Sep 12, 2016 at 10:05:36AM -0500, Tom Lendacky wrote:
>> I can look into that.  The reason I put this here is this is all the
>> early page fault support that is very specific to this file. I modified
>> an existing static function to take advantage of the mapping support.
> 
> Yeah, but all this code is SME-specific and doesn't belong there.
> AFAICT, it uses global/public symbols so there shouldn't be a problem to
> have it in mem_encrypt.c.

Ok, I'll look into moving this into mem_encrypt.c. I'd like to avoid
duplicating code so I may have to make that static function external
unless I find a better way.

Thanks,
Tom

> 
>> Hmmm, maybe... With the change to the early_memremap() the initrd is now
>> identified as BOOT_DATA in relocate_initrd() and so it will be mapped
>> and copied as non-encyrpted data. But since it was encrypted before the
>> call to relocate_initrd() it will copy encrypted bytes which will later
>> be accessed encrypted. That isn't clear though, so I'll rework
>> reserve_initrd() to perform the sme_early_mem_enc() once at the end
>> whether the initrd is re-located or not.
> 
> Makes sense.
> 
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Re: [RFC PATCH v2 10/20] x86: Insure that memory areas are encrypted when possible

[Borislav Petkov]

On Mon, Sep 12, 2016 at 10:05:36AM -0500, Tom Lendacky wrote:
> I can look into that.  The reason I put this here is this is all the
> early page fault support that is very specific to this file. I modified
> an existing static function to take advantage of the mapping support.

Yeah, but all this code is SME-specific and doesn't belong there.
AFAICT, it uses global/public symbols so there shouldn't be a problem to
have it in mem_encrypt.c.

> Hmmm, maybe... With the change to the early_memremap() the initrd is now
> identified as BOOT_DATA in relocate_initrd() and so it will be mapped
> and copied as non-encyrpted data. But since it was encrypted before the
> call to relocate_initrd() it will copy encrypted bytes which will later
> be accessed encrypted. That isn't clear though, so I'll rework
> reserve_initrd() to perform the sme_early_mem_enc() once at the end
> whether the initrd is re-located or not.

Makes sense.

-- 
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.
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Re: [RFC PATCH v2 10/20] x86: Insure that memory areas are encrypted when possible

[Tom Lendacky]

On 09/09/2016 10:53 AM, Borislav Petkov wrote:
> On Mon, Aug 22, 2016 at 05:37:23PM -0500, Tom Lendacky wrote:
>> Encrypt memory areas in place when possible (e.g. zero page, etc.) so
>> that special handling isn't needed afterwards.
>>
>> Signed-off-by: Tom Lendacky 
>> ---
>>  arch/x86/kernel/head64.c |   93 
>> --
>>  arch/x86/kernel/setup.c  |8 
>>  2 files changed, 96 insertions(+), 5 deletions(-)
> 
> ...
> 
>> +int __init early_make_pgtable(unsigned long address)
>> +{
>> +unsigned long physaddr = address - __PAGE_OFFSET;
>> +pmdval_t pmd;
>> +
>> +pmd = (physaddr & PMD_MASK) + early_pmd_flags;
>> +
>> +return __early_make_pgtable(address, pmd);
>> +}
>> +
>> +static void __init create_unencrypted_mapping(void *address, unsigned long 
>> size)
>> +{
>> +unsigned long physaddr = (unsigned long)address - __PAGE_OFFSET;
>> +pmdval_t pmd_flags, pmd;
>> +
>> +if (!sme_me_mask)
>> +return;
>> +
>> +/* Clear the encryption mask from the early_pmd_flags */
>> +pmd_flags = early_pmd_flags & ~sme_me_mask;
>> +
>> +do {
>> +pmd = (physaddr & PMD_MASK) + pmd_flags;
>> +__early_make_pgtable((unsigned long)address, pmd);
>> +
>> +address += PMD_SIZE;
>> +physaddr += PMD_SIZE;
>> +size = (size < PMD_SIZE) ? 0 : size - PMD_SIZE;
>> +} while (size);
>> +}
>> +
>> +static void __init __clear_mapping(unsigned long address)
> 
> Should be called something with "pmd" in the name as it clears a PMD,
> i.e. __clear_pmd_mapping or so.

Ok.

> 
>> +{
>> +unsigned long physaddr = address - __PAGE_OFFSET;
>> +pgdval_t pgd, *pgd_p;
>> +pudval_t pud, *pud_p;
>> +pmdval_t *pmd_p;
>> +
>> +/* Invalid address or early pgt is done ?  */
>> +if (physaddr >= MAXMEM ||
>> +read_cr3() != __sme_pa_nodebug(early_level4_pgt))
>> +return;
>> +
>> +pgd_p = _level4_pgt[pgd_index(address)].pgd;
>> +pgd = *pgd_p;
>> +
>> +if (!pgd)
>> +return;
>> +
>> +/*
>> + * The use of __START_KERNEL_map rather than __PAGE_OFFSET here matches
>> + * __early_make_pgtable where the entry was created.
>> + */
>> +pud_p = (pudval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - 
>> phys_base);
>> +pud_p += pud_index(address);
>> +pud = *pud_p;
>> +
>> +if (!pud)
>> +return;
>> +
>> +pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - 
>> phys_base);
>> +pmd_p[pmd_index(address)] = 0;
>> +}
>> +
>> +static void __init clear_mapping(void *address, unsigned long size)
>> +{
>> +if (!sme_me_mask)
>> +return;
>> +
>> +do {
>> +__clear_mapping((unsigned long)address);
>> +
>> +address += PMD_SIZE;
>> +size = (size < PMD_SIZE) ? 0 : size - PMD_SIZE;
>> +} while (size);
>> +}
>> +
>> +static void __init sme_memcpy(void *dst, void *src, unsigned long size)
>> +{
>> +create_unencrypted_mapping(src, size);
>> +memcpy(dst, src, size);
>> +clear_mapping(src, size);
>> +}
>> +
> 
> In any case, this whole functionality is SME-specific and should be
> somewhere in an SME-specific file. arch/x86/mm/mem_encrypt.c or so...

I can look into that.  The reason I put this here is this is all the
early page fault support that is very specific to this file. I modified
an existing static function to take advantage of the mapping support.

> 
>>  /* Don't add a printk in there. printk relies on the PDA which is not 
>> initialized 
>> yet. */
>>  static void __init clear_bss(void)
>> @@ -122,12 +205,12 @@ static void __init copy_bootdata(char *real_mode_data)
>>  char * command_line;
>>  unsigned long cmd_line_ptr;
>>  
>> -memcpy(_params, real_mode_data, sizeof boot_params);
>> +sme_memcpy(_params, real_mode_data, sizeof boot_params);
> 
> checkpatch.pl:
> 
> WARNING: sizeof boot_params should be sizeof(boot_params)
> #155: FILE: arch/x86/kernel/head64.c:208:
> +   sme_memcpy(_params, real_mode_data, sizeof boot_params);

I can fix that.

> 
>>  sanitize_boot_params(_params);
>>  cmd_line_ptr = get_cmd_line_ptr();
>>  if (cmd_line_ptr) {
>>  command_line = __va(cmd_line_ptr);
>> -memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
>> +sme_memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
>>  }
>>  }
>>  
>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>> index 1489da8..1fdaa11 100644
>> --- a/arch/x86/kernel/setup.c
>> +++ b/arch/x86/kernel/setup.c
>> @@ -114,6 +114,7 @@
>>  #include 
>>  #include 
>>  #include 
>> +#include 
>>  
>>  /*
>>   * max_low_pfn_mapped: highest direct mapped pfn under 4GB
>> @@ -376,6 +377,13 @@ static void __init reserve_initrd(void)
>>  !ramdisk_image || !ramdisk_size)
>>  return; /* No initrd provided by bootloader */
>>  
>> 

Re: [RFC PATCH v2 10/20] x86: Insure that memory areas are encrypted when possible

[Borislav Petkov]

On Mon, Aug 22, 2016 at 05:37:23PM -0500, Tom Lendacky wrote:
> Encrypt memory areas in place when possible (e.g. zero page, etc.) so
> that special handling isn't needed afterwards.
> 
> Signed-off-by: Tom Lendacky 
> ---
>  arch/x86/kernel/head64.c |   93 
> --
>  arch/x86/kernel/setup.c  |8 
>  2 files changed, 96 insertions(+), 5 deletions(-)

...

> +int __init early_make_pgtable(unsigned long address)
> +{
> + unsigned long physaddr = address - __PAGE_OFFSET;
> + pmdval_t pmd;
> +
> + pmd = (physaddr & PMD_MASK) + early_pmd_flags;
> +
> + return __early_make_pgtable(address, pmd);
> +}
> +
> +static void __init create_unencrypted_mapping(void *address, unsigned long 
> size)
> +{
> + unsigned long physaddr = (unsigned long)address - __PAGE_OFFSET;
> + pmdval_t pmd_flags, pmd;
> +
> + if (!sme_me_mask)
> + return;
> +
> + /* Clear the encryption mask from the early_pmd_flags */
> + pmd_flags = early_pmd_flags & ~sme_me_mask;
> +
> + do {
> + pmd = (physaddr & PMD_MASK) + pmd_flags;
> + __early_make_pgtable((unsigned long)address, pmd);
> +
> + address += PMD_SIZE;
> + physaddr += PMD_SIZE;
> + size = (size < PMD_SIZE) ? 0 : size - PMD_SIZE;
> + } while (size);
> +}
> +
> +static void __init __clear_mapping(unsigned long address)

Should be called something with "pmd" in the name as it clears a PMD,
i.e. __clear_pmd_mapping or so.

> +{
> + unsigned long physaddr = address - __PAGE_OFFSET;
> + pgdval_t pgd, *pgd_p;
> + pudval_t pud, *pud_p;
> + pmdval_t *pmd_p;
> +
> + /* Invalid address or early pgt is done ?  */
> + if (physaddr >= MAXMEM ||
> + read_cr3() != __sme_pa_nodebug(early_level4_pgt))
> + return;
> +
> + pgd_p = _level4_pgt[pgd_index(address)].pgd;
> + pgd = *pgd_p;
> +
> + if (!pgd)
> + return;
> +
> + /*
> +  * The use of __START_KERNEL_map rather than __PAGE_OFFSET here matches
> +  * __early_make_pgtable where the entry was created.
> +  */
> + pud_p = (pudval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - 
> phys_base);
> + pud_p += pud_index(address);
> + pud = *pud_p;
> +
> + if (!pud)
> + return;
> +
> + pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - 
> phys_base);
> + pmd_p[pmd_index(address)] = 0;
> +}
> +
> +static void __init clear_mapping(void *address, unsigned long size)
> +{
> + if (!sme_me_mask)
> + return;
> +
> + do {
> + __clear_mapping((unsigned long)address);
> +
> + address += PMD_SIZE;
> + size = (size < PMD_SIZE) ? 0 : size - PMD_SIZE;
> + } while (size);
> +}
> +
> +static void __init sme_memcpy(void *dst, void *src, unsigned long size)
> +{
> + create_unencrypted_mapping(src, size);
> + memcpy(dst, src, size);
> + clear_mapping(src, size);
> +}
> +

In any case, this whole functionality is SME-specific and should be
somewhere in an SME-specific file. arch/x86/mm/mem_encrypt.c or so...

>  /* Don't add a printk in there. printk relies on the PDA which is not 
> initialized 
> yet. */
>  static void __init clear_bss(void)
> @@ -122,12 +205,12 @@ static void __init copy_bootdata(char *real_mode_data)
>   char * command_line;
>   unsigned long cmd_line_ptr;
>  
> - memcpy(_params, real_mode_data, sizeof boot_params);
> + sme_memcpy(_params, real_mode_data, sizeof boot_params);

checkpatch.pl:

WARNING: sizeof boot_params should be sizeof(boot_params)
#155: FILE: arch/x86/kernel/head64.c:208:
+   sme_memcpy(_params, real_mode_data, sizeof boot_params);

>   sanitize_boot_params(_params);
>   cmd_line_ptr = get_cmd_line_ptr();
>   if (cmd_line_ptr) {
>   command_line = __va(cmd_line_ptr);
> - memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
> + sme_memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
>   }
>  }
>  
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 1489da8..1fdaa11 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -114,6 +114,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  
>  /*
>   * max_low_pfn_mapped: highest direct mapped pfn under 4GB
> @@ -376,6 +377,13 @@ static void __init reserve_initrd(void)
>   !ramdisk_image || !ramdisk_size)
>   return; /* No initrd provided by bootloader */
>  
> + /*
> +  * This memory is marked encrypted by the kernel but the ramdisk
> +  * was loaded in the clear by the bootloader, so make sure that
> +  * the ramdisk image is encrypted.
> +  */
> + sme_early_mem_enc(ramdisk_image, ramdisk_end - ramdisk_image);

What happens if we go and relocate the ramdisk? I.e., the function above
this one: relocate_initrd(). We 

[RFC PATCH v2 10/20] x86: Insure that memory areas are encrypted when possible

[Tom Lendacky]

Encrypt memory areas in place when possible (e.g. zero page, etc.) so
that special handling isn't needed afterwards.

Signed-off-by: Tom Lendacky 
---
 arch/x86/kernel/head64.c |   93 --
 arch/x86/kernel/setup.c  |8 
 2 files changed, 96 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 88c7bae..358d7bc 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -47,12 +47,12 @@ static void __init reset_early_page_tables(void)
 }
 
 /* Create a new PMD entry */
-int __init early_make_pgtable(unsigned long address)
+static int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
 {
unsigned long physaddr = address - __PAGE_OFFSET;
pgdval_t pgd, *pgd_p;
pudval_t pud, *pud_p;
-   pmdval_t pmd, *pmd_p;
+   pmdval_t *pmd_p;
 
/* Invalid address or early pgt is done ?  */
if (physaddr >= MAXMEM || read_cr3() != 
__sme_pa_nodebug(early_level4_pgt))
@@ -94,12 +94,95 @@ again:
memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + 
_KERNPG_TABLE;
}
-   pmd = (physaddr & PMD_MASK) + early_pmd_flags;
pmd_p[pmd_index(address)] = pmd;
 
return 0;
 }
 
+int __init early_make_pgtable(unsigned long address)
+{
+   unsigned long physaddr = address - __PAGE_OFFSET;
+   pmdval_t pmd;
+
+   pmd = (physaddr & PMD_MASK) + early_pmd_flags;
+
+   return __early_make_pgtable(address, pmd);
+}
+
+static void __init create_unencrypted_mapping(void *address, unsigned long 
size)
+{
+   unsigned long physaddr = (unsigned long)address - __PAGE_OFFSET;
+   pmdval_t pmd_flags, pmd;
+
+   if (!sme_me_mask)
+   return;
+
+   /* Clear the encryption mask from the early_pmd_flags */
+   pmd_flags = early_pmd_flags & ~sme_me_mask;
+
+   do {
+   pmd = (physaddr & PMD_MASK) + pmd_flags;
+   __early_make_pgtable((unsigned long)address, pmd);
+
+   address += PMD_SIZE;
+   physaddr += PMD_SIZE;
+   size = (size < PMD_SIZE) ? 0 : size - PMD_SIZE;
+   } while (size);
+}
+
+static void __init __clear_mapping(unsigned long address)
+{
+   unsigned long physaddr = address - __PAGE_OFFSET;
+   pgdval_t pgd, *pgd_p;
+   pudval_t pud, *pud_p;
+   pmdval_t *pmd_p;
+
+   /* Invalid address or early pgt is done ?  */
+   if (physaddr >= MAXMEM ||
+   read_cr3() != __sme_pa_nodebug(early_level4_pgt))
+   return;
+
+   pgd_p = _level4_pgt[pgd_index(address)].pgd;
+   pgd = *pgd_p;
+
+   if (!pgd)
+   return;
+
+   /*
+* The use of __START_KERNEL_map rather than __PAGE_OFFSET here matches
+* __early_make_pgtable where the entry was created.
+*/
+   pud_p = (pudval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - 
phys_base);
+   pud_p += pud_index(address);
+   pud = *pud_p;
+
+   if (!pud)
+   return;
+
+   pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - 
phys_base);
+   pmd_p[pmd_index(address)] = 0;
+}
+
+static void __init clear_mapping(void *address, unsigned long size)
+{
+   if (!sme_me_mask)
+   return;
+
+   do {
+   __clear_mapping((unsigned long)address);
+
+   address += PMD_SIZE;
+   size = (size < PMD_SIZE) ? 0 : size - PMD_SIZE;
+   } while (size);
+}
+
+static void __init sme_memcpy(void *dst, void *src, unsigned long size)
+{
+   create_unencrypted_mapping(src, size);
+   memcpy(dst, src, size);
+   clear_mapping(src, size);
+}
+
 /* Don't add a printk in there. printk relies on the PDA which is not 
initialized 
yet. */
 static void __init clear_bss(void)
@@ -122,12 +205,12 @@ static void __init copy_bootdata(char *real_mode_data)
char * command_line;
unsigned long cmd_line_ptr;
 
-   memcpy(_params, real_mode_data, sizeof boot_params);
+   sme_memcpy(_params, real_mode_data, sizeof boot_params);
sanitize_boot_params(_params);
cmd_line_ptr = get_cmd_line_ptr();
if (cmd_line_ptr) {
command_line = __va(cmd_line_ptr);
-   memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
+   sme_memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
}
 }
 
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 1489da8..1fdaa11 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -114,6 +114,7 @@
 #include 
 #include 
 #include 
+#include 
 
 /*
  * max_low_pfn_mapped: highest direct mapped pfn under 4GB
@@ -376,6 +377,13 @@ static void __init reserve_initrd(void)
!ramdisk_image || !ramdisk_size)
return; /* No initrd provided by bootloader */