2020-07-17 17:44:05

by Kees Cook

Subject: [PATCH 03/13] fs/kernel_read_file: Remove FIRMWARE_EFI_EMBEDDED enum

The "FIRMWARE_EFI_EMBEDDED" enum is a "where", not a "what". It
should not be distinguished separately from just "FIRMWARE", as this
confuses the LSMs about what is being loaded. Additionally, there was
no actual validation of the firmware contents happening.

Fixes: e4c2c0ff00ec ("firmware: Add new platform fallback mechanism and firmware_request_platform()")
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
To aid in backporting, this change is made before moving
kernel_read_file() to separate header/source files.
---
drivers/base/firmware_loader/fallback_platform.c | 2 +-
include/linux/fs.h | 3 +--
2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/base/firmware_loader/fallback_platform.c b/drivers/base/firmware_loader/fallback_platform.c
index 685edb7dd05a..6958ab1a8059 100644
--- a/drivers/base/firmware_loader/fallback_platform.c
+++ b/drivers/base/firmware_loader/fallback_platform.c
@@ -17,7 +17,7 @@ int firmware_fallback_platform(struct fw_priv *fw_priv, u32 opt_flags)
if (!(opt_flags & FW_OPT_FALLBACK_PLATFORM))
return -ENOENT;

- rc = security_kernel_load_data(LOADING_FIRMWARE_EFI_EMBEDDED);
+ rc = security_kernel_load_data(LOADING_FIRMWARE);
if (rc)
return rc;

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 95fc775ed937..f50a35d54a61 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2993,11 +2993,10 @@ static inline void i_readcount_inc(struct inode *inode)
#endif
extern int do_pipe_flags(int *, int);

-/* This is a list of *what* is being read, not *how*. */
+/* This is a list of *what* is being read, not *how* nor *where*. */
#define __kernel_read_file_id(id) \
id(UNKNOWN, unknown) \
id(FIRMWARE, firmware) \
- id(FIRMWARE_EFI_EMBEDDED, firmware) \
id(MODULE, kernel-module) \
id(KEXEC_IMAGE, kexec-image) \
id(KEXEC_INITRAMFS, kexec-initramfs) \
--
2.25.1

2020-07-17 19:12:06

by Scott Branden

Subject: Re: [PATCH 03/13] fs/kernel_read_file: Remove FIRMWARE_EFI_EMBEDDED enum

On 2020-07-17 10:42 a.m., Kees Cook wrote:
> The "FIRMWARE_EFI_EMBEDDED" enum is a "where", not a "what". It
> should not be distinguished separately from just "FIRMWARE", as this
> confuses the LSMs about what is being loaded. Additionally, there was
> no actual validation of the firmware contents happening.
>
> Fixes: e4c2c0ff00ec ("firmware: Add new platform fallback mechanism and firmware_request_platform()")
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
Acked-by: Scott Branden <[email protected]>
> ---
> To aid in backporting, this change is made before moving
> kernel_read_file() to separate header/source files.
> ---
> drivers/base/firmware_loader/fallback_platform.c | 2 +-
> include/linux/fs.h | 3 +--
> 2 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/base/firmware_loader/fallback_platform.c b/drivers/base/firmware_loader/fallback_platform.c
> index 685edb7dd05a..6958ab1a8059 100644
> --- a/drivers/base/firmware_loader/fallback_platform.c
> +++ b/drivers/base/firmware_loader/fallback_platform.c
> @@ -17,7 +17,7 @@ int firmware_fallback_platform(struct fw_priv *fw_priv, u32 opt_flags)
> if (!(opt_flags & FW_OPT_FALLBACK_PLATFORM))
> return -ENOENT;
>
> - rc = security_kernel_load_data(LOADING_FIRMWARE_EFI_EMBEDDED);
> + rc = security_kernel_load_data(LOADING_FIRMWARE);
> if (rc)
> return rc;
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 95fc775ed937..f50a35d54a61 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2993,11 +2993,10 @@ static inline void i_readcount_inc(struct inode *inode)
> #endif
> extern int do_pipe_flags(int *, int);
>
> -/* This is a list of *what* is being read, not *how*. */
> +/* This is a list of *what* is being read, not *how* nor *where*. */
> #define __kernel_read_file_id(id) \
> id(UNKNOWN, unknown) \
> id(FIRMWARE, firmware) \
> - id(FIRMWARE_EFI_EMBEDDED, firmware) \
> id(MODULE, kernel-module) \
> id(KEXEC_IMAGE, kexec-image) \
> id(KEXEC_INITRAMFS, kexec-initramfs) \