[PATCH 0/2] efi: cosmetic patches for the error messages when loading certificates

[PATCH 0/2] efi: cosmetic patches for the error messages when loading certificates

[Lee, Chun-Yi]

When loading certificates list from EFI variables, the error
message and efi status code always be emitted to dmesg. 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

This cosmetic patch set moved the above messages to the error
handling code path. And, it adds a function to transfer EFI status
code to string to improve the readability of debug log. The function
can also be used in other EFI log.

Lee, Chun-Yi (2):
  efi: add a function for transferring status to string
  efi: show error messages only when loading certificates is failed

 include/linux/efi.h                           | 26 +++++++++++++++++
 security/integrity/platform_certs/load_uefi.c | 41 ++++++++++++++-------------
 2 files changed, 48 insertions(+), 19 deletions(-)

-- 
2.16.4

[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
to improve the readability of debug log.

Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
---
 include/linux/efi.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/include/linux/efi.h b/include/linux/efi.h
index d87acf62958e..08daf4cdd807 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -42,6 +42,32 @@
 #define EFI_ABORTED		(21 | (1UL << (BITS_PER_LONG-1)))
 #define EFI_SECURITY_VIOLATION	(26 | (1UL << (BITS_PER_LONG-1)))
 
+#define EFI_STATUS_STR(_status) \
+	case EFI_##_status: \
+		return "EFI_" __stringify(_status);
+
+static inline char *
+efi_status_to_str(unsigned long 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)
+	}
+
+	return "";
+}
+
 typedef unsigned long efi_status_t;
 typedef u8 efi_bool_t;
 typedef u16 efi_char16_t;		/* UNICODE character */
-- 
2.16.4

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

[Ard Biesheuvel]

On Thu, 12 Dec 2019 at 10:38, Lee, Chun-Yi <joeyli.kernel@gmail.com> wrote:
>
> This function can be used to transfer EFI status code to string
> to improve the readability of debug log.
>
> Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>

I think I mentioned this the last time you sent this patch: by making
this a static inline, those strings will be copied into each object
file that uses this routine.
Instead, please make it an ordinary function.

> ---
>  include/linux/efi.h | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index d87acf62958e..08daf4cdd807 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -42,6 +42,32 @@
>  #define EFI_ABORTED            (21 | (1UL << (BITS_PER_LONG-1)))
>  #define EFI_SECURITY_VIOLATION (26 | (1UL << (BITS_PER_LONG-1)))
>
> +#define EFI_STATUS_STR(_status) \
> +       case EFI_##_status: \
> +               return "EFI_" __stringify(_status);
> +
> +static inline char *
> +efi_status_to_str(unsigned long 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)
> +       }
> +
> +       return "";
> +}
> +
>  typedef unsigned long efi_status_t;
>  typedef u8 efi_bool_t;
>  typedef u16 efi_char16_t;              /* UNICODE character */
> --
> 2.16.4
>

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

[Joey Lee]

Hi Ard, 

On Thu, Dec 12, 2019 at 11:20:48AM +0000, Ard Biesheuvel wrote:
> On Thu, 12 Dec 2019 at 10:38, Lee, Chun-Yi <joeyli.kernel@gmail.com> wrote:
> >
> > This function can be used to transfer EFI status code to string
> > to improve the readability of debug log.
> >
> > Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
> 
> I think I mentioned this the last time you sent this patch: by making
> this a static inline, those strings will be copied into each object
> file that uses this routine.
> Instead, please make it an ordinary function.
> 

Sorry for I just sent a old version patch. I will send a new one.

Thanks a lot!
Joey Lee 

> > ---
> >  include/linux/efi.h | 26 ++++++++++++++++++++++++++
> >  1 file changed, 26 insertions(+)
> >
> > diff --git a/include/linux/efi.h b/include/linux/efi.h
> > index d87acf62958e..08daf4cdd807 100644
> > --- a/include/linux/efi.h
> > +++ b/include/linux/efi.h
> > @@ -42,6 +42,32 @@
> >  #define EFI_ABORTED            (21 | (1UL << (BITS_PER_LONG-1)))
> >  #define EFI_SECURITY_VIOLATION (26 | (1UL << (BITS_PER_LONG-1)))
> >
> > +#define EFI_STATUS_STR(_status) \
> > +       case EFI_##_status: \
> > +               return "EFI_" __stringify(_status);
> > +
> > +static inline char *
> > +efi_status_to_str(unsigned long 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)
> > +       }
> > +
> > +       return "";
> > +}
> > +
> >  typedef unsigned long efi_status_t;
> >  typedef u8 efi_bool_t;
> >  typedef u16 efi_char16_t;              /* UNICODE character */
> > --
> > 2.16.4
> >

[PATCH 2/2] efi: show error messages only when loading certificates is failed

[Lee, Chun-Yi]

When loading certificates list from EFI variables, the error
message and efi status code always be emitted to dmesg. 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

This cosmetic patch moved the messages to the error handling code
path. And, it also shows the corresponding status string of status
code.

Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
---
 security/integrity/platform_certs/load_uefi.c | 41 ++++++++++++++-------------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
index 81b19c52832b..3b766831d2c5 100644
--- a/security/integrity/platform_certs/load_uefi.c
+++ b/security/integrity/platform_certs/load_uefi.c
@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/kernel.h>
 #include <linux/sched.h>
@@ -39,7 +40,7 @@ static __init bool uefi_check_ignore_db(void)
  * Get a certificate list blob from the named EFI variable.
  */
 static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
-				  unsigned long *size)
+				  unsigned long *size, const char *source)
 {
 	efi_status_t status;
 	unsigned long lsize = 4;
@@ -48,23 +49,31 @@ 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);
-		return NULL;
+		if (status == EFI_NOT_FOUND) {
+			pr_debug("%s list was not found\n", source);
+			return NULL;
+		}
+		goto err;
 	}
 
 	db = kmalloc(lsize, GFP_KERNEL);
-	if (!db)
-		return NULL;
+	if (!db) {
+		status = EFI_OUT_OF_RESOURCES;
+		goto err;
+	}
 
 	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);
-		return NULL;
+		goto err;
 	}
 
 	*size = lsize;
 	return db;
+err:
+	pr_err("Couldn't get %s list: %s (0x%lx)\n",
+		source, efi_status_to_str(status), status);
+	return NULL;
 }
 
 /*
@@ -153,10 +162,8 @@ static int __init load_uefi_certs(void)
 	 * an error if we can't get them.
 	 */
 	if (!uefi_check_ignore_db()) {
-		db = get_cert_list(L"db", &secure_var, &dbsize);
-		if (!db) {
-			pr_err("MODSIGN: Couldn't get UEFI db list\n");
-		} else {
+		db = get_cert_list(L"db", &secure_var, &dbsize, "UEFI:db");
+		if (db) {
 			rc = parse_efi_signature_list("UEFI:db",
 					db, dbsize, get_handler_for_db);
 			if (rc)
@@ -166,10 +173,8 @@ static int __init load_uefi_certs(void)
 		}
 	}
 
-	mok = get_cert_list(L"MokListRT", &mok_var, &moksize);
-	if (!mok) {
-		pr_info("Couldn't get UEFI MokListRT\n");
-	} else {
+	mok = get_cert_list(L"MokListRT", &mok_var, &moksize, "UEFI:MokListRT");
+	if (mok) {
 		rc = parse_efi_signature_list("UEFI:MokListRT",
 					      mok, moksize, get_handler_for_db);
 		if (rc)
@@ -177,10 +182,8 @@ static int __init load_uefi_certs(void)
 		kfree(mok);
 	}
 
-	dbx = get_cert_list(L"dbx", &secure_var, &dbxsize);
-	if (!dbx) {
-		pr_info("Couldn't get UEFI dbx list\n");
-	} else {
+	dbx = get_cert_list(L"dbx", &secure_var, &dbxsize, "UEFI:dbx");
+	if (dbx) {
 		rc = parse_efi_signature_list("UEFI:dbx",
 					      dbx, dbxsize,
 					      get_handler_for_dbx);
-- 
2.16.4