[9/9] integrity: check properly whether EFI GetVariable() is available
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Message ID 20200219171907.11894-10-ardb@kernel.org
State New
Headers show
Series
  • Untitled series #244189
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Commit Message

Ard Biesheuvel Feb. 19, 2020, 5:19 p.m. UTC
Testing the value of the efi.get_variable function pointer is not
the right way to establish whether the platform supports EFI
variables at runtime. Instead, use the newly added granular check
that can test for the presence of each EFI runtime service
individually.

Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 security/integrity/platform_certs/load_uefi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Serge Hallyn Feb. 19, 2020, 8:46 p.m. UTC | #1
On Wed, Feb 19, 2020 at 06:19:07PM +0100, Ard Biesheuvel wrote:
> Testing the value of the efi.get_variable function pointer is not
> the right way to establish whether the platform supports EFI
> variables at runtime. Instead, use the newly added granular check
> that can test for the presence of each EFI runtime service
> individually.
> 
> Cc: James Morris <jmorris@namei.org>
> Cc: "Serge E. Hallyn" <serge@hallyn.com>
> Cc: linux-security-module@vger.kernel.org
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  security/integrity/platform_certs/load_uefi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
> index 111898aad56e..e2fe1bd3abb9 100644
> --- a/security/integrity/platform_certs/load_uefi.c
> +++ b/security/integrity/platform_certs/load_uefi.c
> @@ -76,7 +76,7 @@ static int __init load_uefi_certs(void)
>  	unsigned long dbsize = 0, dbxsize = 0, moksize = 0;
>  	int rc = 0;
>  
> -	if (!efi.get_variable)
> +	if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))

Sorry, where is this defined?

>  		return false;
>  
>  	/* Get db, MokListRT, and dbx.  They might not exist, so it isn't
> -- 
> 2.17.1
Ard Biesheuvel Feb. 19, 2020, 9 p.m. UTC | #2
On Wed, 19 Feb 2020 at 21:46, Serge E. Hallyn <serge@hallyn.com> wrote:
>
> On Wed, Feb 19, 2020 at 06:19:07PM +0100, Ard Biesheuvel wrote:
> > Testing the value of the efi.get_variable function pointer is not
> > the right way to establish whether the platform supports EFI
> > variables at runtime. Instead, use the newly added granular check
> > that can test for the presence of each EFI runtime service
> > individually.
> >
> > Cc: James Morris <jmorris@namei.org>
> > Cc: "Serge E. Hallyn" <serge@hallyn.com>
> > Cc: linux-security-module@vger.kernel.org
> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> > ---
> >  security/integrity/platform_certs/load_uefi.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
> > index 111898aad56e..e2fe1bd3abb9 100644
> > --- a/security/integrity/platform_certs/load_uefi.c
> > +++ b/security/integrity/platform_certs/load_uefi.c
> > @@ -76,7 +76,7 @@ static int __init load_uefi_certs(void)
> >       unsigned long dbsize = 0, dbxsize = 0, moksize = 0;
> >       int rc = 0;
> >
> > -     if (!efi.get_variable)
> > +     if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
>
> Sorry, where is this defined?
>

Apologies, I failed to cc everyone on the whole series.

It is defined in the first patch.

https://lore.kernel.org/linux-efi/20200219171907.11894-1-ardb@kernel.org/
Serge Hallyn Feb. 20, 2020, 3:19 a.m. UTC | #3
On Wed, Feb 19, 2020 at 10:00:11PM +0100, Ard Biesheuvel wrote:
> On Wed, 19 Feb 2020 at 21:46, Serge E. Hallyn <serge@hallyn.com> wrote:
> >
> > On Wed, Feb 19, 2020 at 06:19:07PM +0100, Ard Biesheuvel wrote:
> > > Testing the value of the efi.get_variable function pointer is not
> > > the right way to establish whether the platform supports EFI
> > > variables at runtime. Instead, use the newly added granular check
> > > that can test for the presence of each EFI runtime service
> > > individually.
> > >
> > > Cc: James Morris <jmorris@namei.org>
> > > Cc: "Serge E. Hallyn" <serge@hallyn.com>
> > > Cc: linux-security-module@vger.kernel.org
> > > Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> > > ---
> > >  security/integrity/platform_certs/load_uefi.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
> > > index 111898aad56e..e2fe1bd3abb9 100644
> > > --- a/security/integrity/platform_certs/load_uefi.c
> > > +++ b/security/integrity/platform_certs/load_uefi.c
> > > @@ -76,7 +76,7 @@ static int __init load_uefi_certs(void)
> > >       unsigned long dbsize = 0, dbxsize = 0, moksize = 0;
> > >       int rc = 0;
> > >
> > > -     if (!efi.get_variable)
> > > +     if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
> >
> > Sorry, where is this defined?
> >
> 
> Apologies, I failed to cc everyone on the whole series.
> 
> It is defined in the first patch.
> 
> https://lore.kernel.org/linux-efi/20200219171907.11894-1-ardb@kernel.org/

Gotcha, thanks, I shoulda get-lore-mbox'ed it :)

Acked-by: Serge Hallyn <serge@hallyn.com>

thanks,
-serge

Patch
diff mbox series

diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
index 111898aad56e..e2fe1bd3abb9 100644
--- a/security/integrity/platform_certs/load_uefi.c
+++ b/security/integrity/platform_certs/load_uefi.c
@@ -76,7 +76,7 @@  static int __init load_uefi_certs(void)
 	unsigned long dbsize = 0, dbxsize = 0, moksize = 0;
 	int rc = 0;
 
-	if (!efi.get_variable)
+	if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
 		return false;
 
 	/* Get db, MokListRT, and dbx.  They might not exist, so it isn't