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EFI updates for v6.10: 

- Additional cleanup by Tim for the efivarfs variable name length
   confusion
 
 - Avoid freeing a bogus pointer when virtual remapping is omitted in the
   EFI boot stub
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Merge tag 'efi-next-for-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

Pull EFI updates from Ard Biesheuvel:
 "Only a handful of changes this cycle, consisting of cleanup work and a
  low-prio bugfix:

   - Additional cleanup by Tim for the efivarfs variable name length
     confusion

   - Avoid freeing a bogus pointer when virtual remapping is omitted in
     the EFI boot stub"

* tag 'efi-next-for-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  efi: libstub: only free priv.runtime_map when allocated
  efi: Clear up misconceptions about a maximum variable name size
  efivarfs: Remove unused internal struct members
  Documentation: Mark the 'efivars' sysfs interface as removed
  efi: pstore: Request at most 512 bytes for variable names
This commit is contained in:
Linus Torvalds 2024-05-14 15:19:26 -07:00
parent 614da38e2f 4b2543f7e1
commit 1b10b390d9
9 changed files with 33 additions and 95 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
Documentation/ABI/removed/sysfs-firmware-efi-vars Normal file
View File

@ -0,0 +1,12 @@
What: /sys/firmware/efi/vars
Date: April 2004, removed March 2023
Description:
This directory exposed interfaces for interacting with
EFI variables. For more information on EFI variables,
see 'Variable Services' in the UEFI specification
(section 7.2 in specification version 2.3 Errata D).
The 'efivars' sysfs interface was removed in March of 2023,
after being considered deprecated no later than September
of 2020. Its functionality has been replaced by the
'efivarfs' filesystem.

79
Documentation/ABI/stable/sysfs-firmware-efi-vars
View File

@ -1,79 +0,0 @@
What: /sys/firmware/efi/vars
Date: April 2004
Contact: Matt Domsch <Matt_Domsch@dell.com>
Description:
This directory exposes interfaces for interactive with
EFI variables. For more information on EFI variables,
see 'Variable Services' in the UEFI specification
(section 7.2 in specification version 2.3 Errata D).
In summary, EFI variables are named, and are classified
into separate namespaces through the use of a vendor
GUID. They also have an arbitrary binary value
associated with them.
The efivars module enumerates these variables and
creates a separate directory for each one found. Each
directory has a name of the form "<key>-<vendor guid>"
and contains the following files:
=============== ========================================
attributes: A read-only text file enumerating the
EFI variable flags. Potential values
include:
EFI_VARIABLE_NON_VOLATILE
EFI_VARIABLE_BOOTSERVICE_ACCESS
EFI_VARIABLE_RUNTIME_ACCESS
EFI_VARIABLE_HARDWARE_ERROR_RECORD
EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS
See the EFI documentation for an
explanation of each of these variables.
data: A read-only binary file that can be read
to attain the value of the EFI variable
guid: The vendor GUID of the variable. This
should always match the GUID in the
variable's name.
raw_var: A binary file that can be read to obtain
a structure that contains everything
there is to know about the variable.
For structure definition see "struct
efi_variable" in the kernel sources.
This file can also be written to in
order to update the value of a variable.
For this to work however, all fields of
the "struct efi_variable" passed must
match byte for byte with the structure
read out of the file, save for the value
portion.
**Note** the efi_variable structure
read/written with this file contains a
'long' type that may change widths
depending on your underlying
architecture.
size: As ASCII representation of the size of
the variable's value.
=============== ========================================
In addition, two other magic binary files are provided
in the top-level directory and are used for adding and
removing variables:
=============== ========================================
new_var: Takes a "struct efi_variable" and
instructs the EFI firmware to create a
new variable.
del_var: Takes a "struct efi_variable" and
instructs the EFI firmware to remove any
variable that has a matching vendor GUID
and variable key name.
=============== ========================================

2
Documentation/filesystems/efivarfs.rst
View File

@ -40,4 +40,4 @@ accidentally.
*See also:*
- Documentation/admin-guide/acpi/ssdt-overlays.rst
- Documentation/ABI/stable/sysfs-firmware-efi-vars
- Documentation/ABI/removed/sysfs-firmware-efi-vars

10
drivers/firmware/efi/efi-pstore.c
View File

@ -162,7 +162,15 @@ static ssize_t efi_pstore_read(struct pstore_record *record)
efi_status_t status;
for (;;) {
varname_size = 1024;
/*
* A small set of old UEFI implementations reject sizes
* above a certain threshold, the lowest seen in the wild
* is 512.
*
* TODO: Commonize with the iteration implementation in
* fs/efivarfs to keep all the quirks in one place.
*/
varname_size = 512;
/*
* If this is the first read() call in the pstore enumeration,

4
drivers/firmware/efi/libstub/fdt.c
View File

@ -335,8 +335,8 @@ fail_free_new_fdt:
fail:
efi_free(fdt_size, fdt_addr);
efi_bs_call(free_pool, priv.runtime_map);
if (!efi_novamap)
efi_bs_call(free_pool, priv.runtime_map);
return EFI_LOAD_ERROR;
}

2
drivers/firmware/efi/vars.c
View File

@ -215,7 +215,7 @@ efi_status_t efivar_set_variable_locked(efi_char16_t *name, efi_guid_t *vendor,
if (data_size > 0) {
status = check_var_size(nonblocking, attr,
data_size + ucs2_strsize(name, 1024));
data_size + ucs2_strsize(name, EFI_VAR_NAME_LEN));
if (status != EFI_SUCCESS)
return status;
}

5
fs/efivarfs/internal.h
View File

@ -24,11 +24,8 @@ struct efivarfs_fs_info {
struct efi_variable {
efi_char16_t VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
efi_guid_t VendorGuid;
unsigned long DataSize;
__u8 Data[1024];
efi_status_t Status;
__u32 Attributes;
} __attribute__((packed));
};
struct efivar_entry {
struct efi_variable var;

5
fs/efivarfs/vars.c
View File

@ -295,9 +295,9 @@ static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor,
unsigned long strsize1, strsize2;
bool found = false;
strsize1 = ucs2_strsize(variable_name, 1024);
strsize1 = ucs2_strsize(variable_name, EFI_VAR_NAME_LEN);
list_for_each_entry_safe(entry, n, head, list) {
strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
strsize2 = ucs2_strsize(entry->var.VariableName, EFI_VAR_NAME_LEN);
if (strsize1 == strsize2 &&
!memcmp(variable_name, &(entry->var.VariableName),
strsize2) &&
@ -396,6 +396,7 @@ int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *,
do {
variable_name_size = 512;
BUILD_BUG_ON(EFI_VAR_NAME_LEN < 512);
status = efivar_get_next_variable(&variable_name_size,
variable_name,

9
include/linux/efi.h
View File

@ -1072,12 +1072,11 @@ static inline u64 efivar_reserved_space(void) { return 0; }
#endif
/*
* The maximum size of VariableName + Data = 1024
* Therefore, it's reasonable to save that much
* space in each part of the structure,
* and we use a page for reading/writing.
* There is no actual upper limit specified for the variable name size.
*
* This limit exists only for practical purposes, since name conversions
* are bounds-checked and name data is occasionally stored in-line.
*/
#define EFI_VAR_NAME_LEN 1024
int efivars_register(struct efivars *efivars,