proxmox-mirrors/efi-boot-shim
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Check that platform is in user mode before doing any validation

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This commit is contained in:
Matthew Garrett 2012-06-12 02:12:31 -04:00
parent 0db1af8aeb
commit b6db0dd4db
2 changed files with 45 additions and 3 deletions
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1
TODO
View File

@ -1,4 +1,3 @@
Fall through if not in user mode
Check against blacklist
Attempt to just LoadImage and StartImage?
Support for netbooting

47
shim.c
View File

@ -50,6 +50,33 @@ static EFI_STATUS (EFIAPI *entry_point) (EFI_HANDLE image_handle, EFI_SYSTEM_TAB
#include "cert.h"
static EFI_STATUS get_variable (CHAR16 *name, EFI_GUID guid,
unsigned int *size,void **buffer)
{
EFI_STATUS efi_status;
UINT32 attributes;
char allocate = !!(*size);
efi_status = uefi_call_wrapper(RT->GetVariable, 5, name, &guid,
&attributes, size, NULL);
if (efi_status != EFI_BUFFER_TOO_SMALL || !allocate)
return efi_status;
if (allocate)
*buffer = AllocatePool(*size);
if (!*buffer) {
Print(L"Unable to allocate variable buffer\n");
return EFI_OUT_OF_RESOURCES;
}
efi_status = uefi_call_wrapper(RT->GetVariable, 5, name, &guid,
&attributes, size, *buffer);
return efi_status;
}
/*
* Perform basic bounds checking of the intra-image pointers
*/
@ -173,17 +200,33 @@ static EFI_STATUS verify_buffer (char *data, int datasize,
{
unsigned int size = datasize;
unsigned int ctxsize;
void *ctx;
void *ctx = NULL;
UINT8 sb, setupmode;
UINT8 hash[SHA256_DIGEST_SIZE];
EFI_STATUS status = EFI_ACCESS_DENIED;
char *hashbase;
unsigned int hashsize;
WIN_CERTIFICATE_EFI_PKCS *cert;
unsigned int SumOfBytesHashed, SumOfSectionBytes;
unsigned int index, pos;
unsigned int index, pos, charsize = sizeof(char);
EFI_IMAGE_SECTION_HEADER *Section;
EFI_IMAGE_SECTION_HEADER *SectionHeader = NULL;
EFI_IMAGE_SECTION_HEADER *SectionCache;
EFI_GUID global_var = EFI_GLOBAL_VARIABLE;
status = get_variable(L"SecureBoot", global_var, &charsize, (void *)&sb);
/* FIXME - more paranoia here? */
if (status != EFI_SUCCESS || sb != 1) {
status = EFI_SUCCESS;
goto done;
}
status = get_variable(L"SetupMode", global_var, &charsize, (void *)&setupmode);
if (status == EFI_SUCCESS && setupmode == 1) {
goto done;
}
cert = ImageAddress (data, size, context->SecDir->VirtualAddress);