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efi_loader: Fix EFI_VARIABLE_APPEND_WRITE hash check

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According to UEFI v2.10 spec section 8.2.6, if a caller invokes the
SetVariables() service, it will produce a digest from hash(VariableName,
VendorGuid, Attributes, TimeStamp, DataNew_variable_content), then the
firmware that implements the SetVariable() service will compare the
digest with the result of applying the signer’s public key to the
signature. For EFI variable append write, efitools sign-efi-sig-list has
an option "-a" to add EFI_VARIABLE_APPEND_WRITE attr, and u-boot will
drop this attribute in efi_set_variable_int(). So if a caller uses
"sign-efi-sig-list -a" to create the authenticated variable, this append
write will fail in the u-boot due to "hash check failed".

This patch resumes writing the EFI_VARIABLE_APPEND_WRITE attr to ensure
that the hash check is correct. And also update the "test_efi_secboot"
test case to compliance with the change.

Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>
This commit is contained in:
Weizhao Ouyang 2024-05-08 19:13:12 +08:00 • committed by Heinrich Schuchardt
parent 1ebd659cf0
commit 3b7d26eb2b
4 changed files with 20 additions and 10 deletions
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6
lib/efi_loader/efi_variable.c
View file

@ -288,7 +288,6 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
/* check if a variable exists */
var = efi_var_mem_find(vendor, variable_name, NULL);
append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
attributes &= ~EFI_VARIABLE_APPEND_WRITE;
delete = !append && (!data_size || !attributes);
/* check attributes */
@ -304,7 +303,7 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
/* attributes won't be changed */
if (!delete &&
((ro_check && var->attr != attributes) ||
((ro_check && var->attr != (attributes & ~EFI_VARIABLE_APPEND_WRITE)) ||
(!ro_check && ((var->attr & ~EFI_VARIABLE_READ_ONLY)
!= (attributes & ~EFI_VARIABLE_READ_ONLY))))) {
return EFI_INVALID_PARAMETER;
@ -378,7 +377,8 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
for (; *old_data; ++old_data)
;
++old_data;
ret = efi_var_mem_ins(variable_name, vendor, attributes,
ret = efi_var_mem_ins(variable_name, vendor,
attributes & ~EFI_VARIABLE_APPEND_WRITE,
var->length, old_data, data_size, data,
time);
} else {