[PATCH 1/2] efi: add a function for transferring status to string

[PATCH 1/2] efi: add a function for transferring status to string

[Lee, Chun-Yi]

This function can be used to transfer EFI status code to string
for printing out debug message. Using this function can improve
the readability of log.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
---
 include/linux/efi.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 54357a258b35..a43cb0dc37af 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1768,4 +1768,32 @@ struct linux_efi_memreserve {
 #define EFI_MEMRESERVE_COUNT(size) (((size) - sizeof(struct linux_efi_memreserve)) \
 	/ sizeof(((struct linux_efi_memreserve *)0)->entry[0]))
 
+#define EFI_STATUS_STR(_status) \
+case EFI_##_status: \
+	return "EFI_" __stringify(_status);
+
+static inline char *
+efi_status_to_str(efi_status_t status)
+{
+	switch (status) {
+	EFI_STATUS_STR(SUCCESS)
+	EFI_STATUS_STR(LOAD_ERROR)
+	EFI_STATUS_STR(INVALID_PARAMETER)
+	EFI_STATUS_STR(UNSUPPORTED)
+	EFI_STATUS_STR(BAD_BUFFER_SIZE)
+	EFI_STATUS_STR(BUFFER_TOO_SMALL)
+	EFI_STATUS_STR(NOT_READY)
+	EFI_STATUS_STR(DEVICE_ERROR)
+	EFI_STATUS_STR(WRITE_PROTECTED)
+	EFI_STATUS_STR(OUT_OF_RESOURCES)
+	EFI_STATUS_STR(NOT_FOUND)
+	EFI_STATUS_STR(ABORTED)
+	EFI_STATUS_STR(SECURITY_VIOLATION)
+	default:
+		pr_warn("Unknown efi status: 0x%lx", status);
+	}
+
+	return "Unknown efi status";
+}
+
 #endif /* _LINUX_EFI_H */
-- 
2.16.4

[PATCH 2/2] efi: print appropriate status message when loading certificates

[Lee, Chun-Yi]

When loading certificates list from UEFI variable, the original error
message direct shows the efi status code from UEFI firmware. It looks
ugly:

[    2.335031] Couldn't get size: 0x800000000000000e
[    2.335032] Couldn't get UEFI MokListRT
[    2.339985] Couldn't get size: 0x800000000000000e
[    2.339987] Couldn't get UEFI dbx list

So, this patch shows the status string instead of status code.

On the other hand, the error message of EFI_NOT_FOUND
(0x800000000000000e) doesn't need to be exposed because kernel
already prints "Couldn't get UEFI..." message. This patch also
filtered out it.

Link: https://forums.opensuse.org/showthread.php/535324-MODSIGN-Couldn-t-get-UEFI-db-list?p=2897516#post2897516
Cc: James Morris <jmorris@namei.org>
Cc: Serge E. Hallyn" <serge@hallyn.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: Josh Boyer <jwboyer@fedoraproject.org>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
---
 security/integrity/platform_certs/load_uefi.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
index 81b19c52832b..fe261166621f 100644
--- a/security/integrity/platform_certs/load_uefi.c
+++ b/security/integrity/platform_certs/load_uefi.c
@@ -48,7 +48,9 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
 
 	status = efi.get_variable(name, guid, NULL, &lsize, &tmpdb);
 	if (status != EFI_BUFFER_TOO_SMALL) {
-		pr_err("Couldn't get size: 0x%lx\n", status);
+		if (status != EFI_NOT_FOUND)
+			pr_err("Couldn't get size: %s\n",
+				efi_status_to_str(status));
 		return NULL;
 	}
 
@@ -59,7 +61,8 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
 	status = efi.get_variable(name, guid, NULL, &lsize, db);
 	if (status != EFI_SUCCESS) {
 		kfree(db);
-		pr_err("Error reading db var: 0x%lx\n", status);
+		pr_err("Error reading db var: %s\n",
+			efi_status_to_str(status));
 		return NULL;
 	}
 
-- 
2.16.4

Re: [PATCH 2/2] efi: print appropriate status message when loading certificates

[Ard Biesheuvel]

On Fri, 22 Mar 2019 at 11:34, Lee, Chun-Yi <joeyli.kernel@gmail.com> wrote:
>
> When loading certificates list from UEFI variable, the original error
> message direct shows the efi status code from UEFI firmware. It looks
> ugly:
>
> [    2.335031] Couldn't get size: 0x800000000000000e
> [    2.335032] Couldn't get UEFI MokListRT
> [    2.339985] Couldn't get size: 0x800000000000000e
> [    2.339987] Couldn't get UEFI dbx list
>

Why is it an error in the first place if these EFI variables do not exist?


> So, this patch shows the status string instead of status code.
>
> On the other hand, the error message of EFI_NOT_FOUND
> (0x800000000000000e) doesn't need to be exposed because kernel
> already prints "Couldn't get UEFI..." message. This patch also
> filtered out it.
>
> Link: https://forums.opensuse.org/showthread.php/535324-MODSIGN-Couldn-t-get-UEFI-db-list?p=2897516#post2897516
> Cc: James Morris <jmorris@namei.org>
> Cc: Serge E. Hallyn" <serge@hallyn.com>
> Cc: David Howells <dhowells@redhat.com>
> Cc: Nayna Jain <nayna@linux.ibm.com>
> Cc: Josh Boyer <jwboyer@fedoraproject.org>
> Cc: Mimi Zohar <zohar@linux.ibm.com>
> Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
> ---
>  security/integrity/platform_certs/load_uefi.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
> index 81b19c52832b..fe261166621f 100644
> --- a/security/integrity/platform_certs/load_uefi.c
> +++ b/security/integrity/platform_certs/load_uefi.c
> @@ -48,7 +48,9 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
>
>         status = efi.get_variable(name, guid, NULL, &lsize, &tmpdb);
>         if (status != EFI_BUFFER_TOO_SMALL) {
> -               pr_err("Couldn't get size: 0x%lx\n", status);
> +               if (status != EFI_NOT_FOUND)
> +                       pr_err("Couldn't get size: %s\n",
> +                               efi_status_to_str(status));
>                 return NULL;
>         }
>
> @@ -59,7 +61,8 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
>         status = efi.get_variable(name, guid, NULL, &lsize, db);
>         if (status != EFI_SUCCESS) {
>                 kfree(db);
> -               pr_err("Error reading db var: 0x%lx\n", status);
> +               pr_err("Error reading db var: %s\n",
> +                       efi_status_to_str(status));
>                 return NULL;
>         }
>
> --
> 2.16.4
>

Re: [PATCH 2/2] efi: print appropriate status message when loading certificates

[jlee]

Hi Ard,

On Fri, Mar 22, 2019 at 03:27:46PM +0100, Ard Biesheuvel wrote:
> On Fri, 22 Mar 2019 at 11:34, Lee, Chun-Yi <joeyli.kernel@gmail.com> wrote:
> >
> > When loading certificates list from UEFI variable, the original error
> > message direct shows the efi status code from UEFI firmware. It looks
> > ugly:
> >
> > [    2.335031] Couldn't get size: 0x800000000000000e
> > [    2.335032] Couldn't get UEFI MokListRT
> > [    2.339985] Couldn't get size: 0x800000000000000e
> > [    2.339987] Couldn't get UEFI dbx list
> >
> 
> Why is it an error in the first place if these EFI variables do not exist?
> 

As you said, the error message should only be exposed when
these EFI variables exist. I will change it in next version of
my patch.

Thanks a lot!
Joey Lee

> 
> > So, this patch shows the status string instead of status code.
> >
> > On the other hand, the error message of EFI_NOT_FOUND
> > (0x800000000000000e) doesn't need to be exposed because kernel
> > already prints "Couldn't get UEFI..." message. This patch also
> > filtered out it.
> >
> > Link: https://forums.opensuse.org/showthread.php/535324-MODSIGN-Couldn-t-get-UEFI-db-list?p=2897516#post2897516
> > Cc: James Morris <jmorris@namei.org>
> > Cc: Serge E. Hallyn" <serge@hallyn.com>
> > Cc: David Howells <dhowells@redhat.com>
> > Cc: Nayna Jain <nayna@linux.ibm.com>
> > Cc: Josh Boyer <jwboyer@fedoraproject.org>
> > Cc: Mimi Zohar <zohar@linux.ibm.com>
> > Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
> > ---
> >  security/integrity/platform_certs/load_uefi.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
> > index 81b19c52832b..fe261166621f 100644
> > --- a/security/integrity/platform_certs/load_uefi.c
> > +++ b/security/integrity/platform_certs/load_uefi.c
> > @@ -48,7 +48,9 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
> >
> >         status = efi.get_variable(name, guid, NULL, &lsize, &tmpdb);
> >         if (status != EFI_BUFFER_TOO_SMALL) {
> > -               pr_err("Couldn't get size: 0x%lx\n", status);
> > +               if (status != EFI_NOT_FOUND)
> > +                       pr_err("Couldn't get size: %s\n",
> > +                               efi_status_to_str(status));
> >                 return NULL;
> >         }
> >
> > @@ -59,7 +61,8 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
> >         status = efi.get_variable(name, guid, NULL, &lsize, db);
> >         if (status != EFI_SUCCESS) {
> >                 kfree(db);
> > -               pr_err("Error reading db var: 0x%lx\n", status);
> > +               pr_err("Error reading db var: %s\n",
> > +                       efi_status_to_str(status));
> >                 return NULL;
> >         }
> >
> > --
> > 2.16.4
> >