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efi_loader: carve out efi_check_pe()

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Carve out a function to check that a buffer contains a PE-COFF image.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
This commit is contained in:
Heinrich Schuchardt 2021-01-12 12:40:32 +01:00
parent dd860b90ff
commit 5dad05a0e6
2 changed files with 48 additions and 34 deletions
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2
include/efi_loader.h
View file

@ -460,6 +460,8 @@ efi_status_t efi_set_watchdog(unsigned long timeout);
/* Called from places to check whether a timer expired */
void efi_timer_check(void);
/* Check if a buffer contains a PE-COFF image */
efi_status_t efi_check_pe(void *buffer, size_t size, void **nt_header);
/* PE loader implementation */
efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
void *efi, size_t efi_size,

80
lib/efi_loader/efi_image_loader.c
View file

@ -675,6 +675,46 @@ static bool efi_image_authenticate(void *efi, size_t efi_size)
}
#endif /* CONFIG_EFI_SECURE_BOOT */
/**
* efi_check_pe() - check if a memory buffer contains a PE-COFF image
*
* @buffer: buffer to check
* @size: size of buffer
* @nt_header: on return pointer to NT header of PE-COFF image
* Return: EFI_SUCCESS if the buffer contains a PE-COFF image
*/
efi_status_t efi_check_pe(void *buffer, size_t size, void **nt_header)
{
IMAGE_DOS_HEADER *dos = buffer;
IMAGE_NT_HEADERS32 *nt;
if (size < sizeof(*dos))
return EFI_INVALID_PARAMETER;
/* Check for DOS magix */
if (dos->e_magic != IMAGE_DOS_SIGNATURE)
return EFI_INVALID_PARAMETER;
/*
* Check if the image section header fits into the file. Knowing that at
* least one section header follows we only need to check for the length
* of the 64bit header which is longer than the 32bit header.
*/
if (size < dos->e_lfanew + sizeof(IMAGE_NT_HEADERS32))
return EFI_INVALID_PARAMETER;
nt = (IMAGE_NT_HEADERS32 *)((u8 *)buffer + dos->e_lfanew);
/* Check for PE-COFF magic */
if (nt->Signature != IMAGE_NT_SIGNATURE)
return EFI_INVALID_PARAMETER;
if (nt_header)
*nt_header = nt;
return EFI_SUCCESS;
}
/**
* efi_load_pe() - relocate EFI binary
*
@ -705,36 +745,10 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
int supported = 0;
efi_status_t ret;
/* Sanity check for a file header */
if (efi_size < sizeof(*dos)) {
log_err("Truncated DOS Header\n");
ret = EFI_LOAD_ERROR;
goto err;
}
dos = efi;
if (dos->e_magic != IMAGE_DOS_SIGNATURE) {
log_err("Invalid DOS Signature\n");
ret = EFI_LOAD_ERROR;
goto err;
}
/*
* Check if the image section header fits into the file. Knowing that at
* least one section header follows we only need to check for the length
* of the 64bit header which is longer than the 32bit header.
*/
if (efi_size < dos->e_lfanew + sizeof(IMAGE_NT_HEADERS64)) {
log_err("Invalid offset for Extended Header\n");
ret = EFI_LOAD_ERROR;
goto err;
}
nt = (void *) ((char *)efi + dos->e_lfanew);
if (nt->Signature != IMAGE_NT_SIGNATURE) {
log_err("Invalid NT Signature\n");
ret = EFI_LOAD_ERROR;
goto err;
ret = efi_check_pe(efi, efi_size, (void **)&nt);
if (ret != EFI_SUCCESS) {
log_err("Not a PE-COFF file\n");
return EFI_LOAD_ERROR;
}
for (i = 0; machines[i]; i++)
@ -746,8 +760,7 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
if (!supported) {
log_err("Machine type 0x%04x is not supported\n",
nt->FileHeader.Machine);
ret = EFI_LOAD_ERROR;
goto err;
return EFI_LOAD_ERROR;
}
num_sections = nt->FileHeader.NumberOfSections;
@ -757,8 +770,7 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
if (efi_size < ((void *)sections + sizeof(sections[0]) * num_sections
- efi)) {
log_err("Invalid number of sections: %d\n", num_sections);
ret = EFI_LOAD_ERROR;
goto err;
return EFI_LOAD_ERROR;
}
/* Authenticate an image */