diff options
Diffstat (limited to 'src/interface/efi/efi_init.c')
| -rw-r--r-- | src/interface/efi/efi_init.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/src/interface/efi/efi_init.c b/src/interface/efi/efi_init.c index ed9707f2c..70212b184 100644 --- a/src/interface/efi/efi_init.c +++ b/src/interface/efi/efi_init.c @@ -21,9 +21,12 @@ FILE_LICENCE ( GPL2_OR_LATER ); #include <string.h> #include <errno.h> +#include <endian.h> #include <ipxe/init.h> +#include <ipxe/rotate.h> #include <ipxe/efi/efi.h> #include <ipxe/efi/efi_driver.h> +#include <ipxe/efi/efi_utils.h> #include <ipxe/efi/Protocol/LoadedImage.h> /** Image handle passed to entry point */ @@ -32,6 +35,9 @@ EFI_HANDLE efi_image_handle; /** Loaded image protocol for this image */ EFI_LOADED_IMAGE_PROTOCOL *efi_loaded_image; +/** Device path for the loaded image's device handle */ +EFI_DEVICE_PATH_PROTOCOL *efi_loaded_image_path; + /** System table passed to entry point * * We construct the symbol name efi_systab via the PLATFORM macro. @@ -47,6 +53,16 @@ int efi_shutdown_in_progress; /** Event used to signal shutdown */ static EFI_EVENT efi_shutdown_event; +/** Stack cookie */ +unsigned long __stack_chk_guard; + +/** Exit function + * + * Cached to minimise external dependencies when a stack check + * failure is triggered. + */ +static EFI_EXIT efi_exit; + /* Forward declarations */ static EFI_STATUS EFIAPI efi_unload ( EFI_HANDLE image_handle ); @@ -88,6 +104,46 @@ static void * efi_find_table ( EFI_GUID *guid ) { } /** + * Construct a stack cookie value + * + * @v handle Image handle + * @ret cookie Stack cookie + */ +__attribute__ (( noinline )) unsigned long +efi_stack_cookie ( EFI_HANDLE handle ) { + unsigned long cookie = 0; + unsigned int rotation = ( 8 * sizeof ( cookie ) / 4 ); + + /* There is no viable source of entropy available at this + * point. Construct a value that is at least likely to vary + * between platforms and invocations. + */ + cookie ^= ( ( unsigned long ) handle ); + cookie = roll ( cookie, rotation ); + cookie ^= ( ( unsigned long ) &handle ); + cookie = roll ( cookie, rotation ); + cookie ^= profile_timestamp(); + cookie = roll ( cookie, rotation ); + cookie ^= build_id; + + /* Ensure that the value contains a NUL byte, to act as a + * runaway string terminator. Construct the NUL using a shift + * rather than a mask, to avoid losing valuable entropy in the + * lower-order bits. + */ + cookie <<= 8; + + /* Ensure that the NUL byte is placed at the bottom of the + * stack cookie, to avoid potential disclosure via an + * unterminated string. + */ + if ( __BYTE_ORDER == __BIG_ENDIAN ) + cookie >>= 8; + + return cookie; +} + +/** * Initialise EFI environment * * @v image_handle Image handle @@ -100,6 +156,9 @@ EFI_STATUS efi_init ( EFI_HANDLE image_handle, struct efi_protocol *prot; struct efi_config_table *tab; void *loaded_image; + void *device_path; + void *device_path_copy; + size_t device_path_len; EFI_STATUS efirc; int rc; @@ -130,6 +189,9 @@ EFI_STATUS efi_init ( EFI_HANDLE image_handle, DBGC ( systab, "EFI handle %p systab %p\n", image_handle, systab ); bs = systab->BootServices; + /* Store abort function pointer */ + efi_exit = bs->Exit; + /* Look up used protocols */ for_each_table_entry ( prot, EFI_PROTOCOLS ) { if ( ( efirc = bs->LocateProtocol ( &prot->guid, NULL, @@ -175,6 +237,33 @@ EFI_STATUS efi_init ( EFI_HANDLE image_handle, DBGC ( systab, "EFI image base address %p\n", efi_loaded_image->ImageBase ); + /* Get loaded image's device handle's device path */ + if ( ( efirc = bs->OpenProtocol ( efi_loaded_image->DeviceHandle, + &efi_device_path_protocol_guid, + &device_path, image_handle, NULL, + EFI_OPEN_PROTOCOL_GET_PROTOCOL ) ) != 0 ) { + rc = -EEFI ( efirc ); + DBGC ( systab, "EFI could not get loaded image's device path: " + "%s", strerror ( rc ) ); + goto err_no_device_path; + } + + /* Make a copy of the loaded image's device handle's device + * path, since the device handle itself may become invalidated + * when we load our own drivers. + */ + device_path_len = ( efi_devpath_len ( device_path ) + + sizeof ( EFI_DEVICE_PATH_PROTOCOL ) ); + if ( ( efirc = bs->AllocatePool ( EfiBootServicesData, device_path_len, + &device_path_copy ) ) != 0 ) { + rc = -EEFI ( efirc ); + goto err_alloc_device_path; + } + memcpy ( device_path_copy, device_path, device_path_len ); + efi_loaded_image_path = device_path_copy; + DBGC ( systab, "EFI image device path %s\n", + efi_devpath_text ( efi_loaded_image_path ) ); + /* EFI is perfectly capable of gracefully shutting down any * loaded devices if it decides to fall back to a legacy boot. * For no particularly comprehensible reason, it doesn't @@ -206,6 +295,9 @@ EFI_STATUS efi_init ( EFI_HANDLE image_handle, err_driver_install: bs->CloseEvent ( efi_shutdown_event ); err_create_event: + bs->FreePool ( efi_loaded_image_path ); + err_alloc_device_path: + err_no_device_path: err_no_loaded_image: err_missing_table: err_missing_protocol: @@ -236,7 +328,36 @@ static EFI_STATUS EFIAPI efi_unload ( EFI_HANDLE image_handle __unused ) { /* Uninstall exit boot services event */ bs->CloseEvent ( efi_shutdown_event ); + /* Free copy of loaded image's device handle's device path */ + bs->FreePool ( efi_loaded_image_path ); + DBGC ( systab, "EFI image unloaded\n" ); return 0; } + +/** + * Abort on stack check failure + * + */ +__attribute__ (( noreturn )) void __stack_chk_fail ( void ) { + EFI_STATUS efirc; + int rc; + + /* Report failure (when debugging) */ + DBGC ( efi_systab, "EFI stack check failed (cookie %#lx); aborting\n", + __stack_chk_guard ); + + /* Attempt to exit cleanly with an error status */ + if ( efi_exit ) { + efirc = efi_exit ( efi_image_handle, EFI_COMPROMISED_DATA, + 0, NULL ); + rc = -EEFI ( efirc ); + DBGC ( efi_systab, "EFI stack check exit failed: %s\n", + strerror ( rc ) ); + } + + /* If the exit fails for any reason, lock the system */ + while ( 1 ) {} + +} |