Commit 4a568ce2 authored by Arvind Sankar's avatar Arvind Sankar Committed by Ard Biesheuvel
Browse files

efi/x86: Add a quirk to support command line arguments on Dell EFI firmware 



At least some versions of Dell EFI firmware pass the entire
EFI_LOAD_OPTION descriptor, rather than just the OptionalData part, to
the loaded image. This was verified with firmware revision 2.15.0 on a
Dell Precision T3620 by Jacobo Pantoja.

To handle this, add a quirk to check if the options look like a valid
EFI_LOAD_OPTION descriptor, and if so, use the OptionalData part as the
command line.

Signed-off-by: default avatarArvind Sankar <nivedita@alum.mit.edu>
Reported-by: default avatarJacobo Pantoja <jacobopantoja@gmail.com>
Link: https://lore.kernel.org/linux-efi/20200907170021.GA2284449@rani.riverdale.lan/
Link: https://lore.kernel.org/r/20200914213535.933454-2-nivedita@alum.mit.edu


Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent c1df5e0c

drivers/firmware/efi/libstub/efi-stub-helper.c

+100 −1
Original line number Diff line number Diff line
@@ -230,6 +230,102 @@ efi_status_t efi_parse_options(char const *cmdline) 
	return EFI_SUCCESS;

}



/*

 * The EFI_LOAD_OPTION descriptor has the following layout:

 *	u32 Attributes;

 *	u16 FilePathListLength;

 *	u16 Description[];

 *	efi_device_path_protocol_t FilePathList[];

 *	u8 OptionalData[];

 *

 * This function validates and unpacks the variable-size data fields.

 */

static

bool efi_load_option_unpack(efi_load_option_unpacked_t *dest,

			    const efi_load_option_t *src, size_t size)

{

	const void *pos;

	u16 c;

	efi_device_path_protocol_t header;

	const efi_char16_t *description;

	const efi_device_path_protocol_t *file_path_list;



	if (size < offsetof(efi_load_option_t, variable_data))

		return false;

	pos = src->variable_data;

	size -= offsetof(efi_load_option_t, variable_data);



	if ((src->attributes & ~EFI_LOAD_OPTION_MASK) != 0)

		return false;



	/* Scan description. */

	description = pos;

	do {

		if (size < sizeof(c))

			return false;

		c = *(const u16 *)pos;

		pos += sizeof(c);

		size -= sizeof(c);

	} while (c != L'\0');



	/* Scan file_path_list. */

	file_path_list = pos;

	do {

		if (size < sizeof(header))

			return false;

		header = *(const efi_device_path_protocol_t *)pos;

		if (header.length < sizeof(header))

			return false;

		if (size < header.length)

			return false;

		pos += header.length;

		size -= header.length;

	} while ((header.type != EFI_DEV_END_PATH && header.type != EFI_DEV_END_PATH2) ||

		 (header.sub_type != EFI_DEV_END_ENTIRE));

	if (pos != (const void *)file_path_list + src->file_path_list_length)

		return false;



	dest->attributes = src->attributes;

	dest->file_path_list_length = src->file_path_list_length;

	dest->description = description;

	dest->file_path_list = file_path_list;

	dest->optional_data_size = size;

	dest->optional_data = size ? pos : NULL;



	return true;

}



/*

 * At least some versions of Dell firmware pass the entire contents of the

 * Boot#### variable, i.e. the EFI_LOAD_OPTION descriptor, rather than just the

 * OptionalData field.

 *

 * Detect this case and extract OptionalData.

 */

void efi_apply_loadoptions_quirk(const void **load_options, int *load_options_size)

{

	const efi_load_option_t *load_option = *load_options;

	efi_load_option_unpacked_t load_option_unpacked;



	if (!IS_ENABLED(CONFIG_X86))

		return;

	if (!load_option)

		return;

	if (*load_options_size < sizeof(*load_option))

		return;

	if ((load_option->attributes & ~EFI_LOAD_OPTION_BOOT_MASK) != 0)

		return;



	if (!efi_load_option_unpack(&load_option_unpacked, load_option, *load_options_size))

		return;



	efi_warn_once(FW_BUG "LoadOptions is an EFI_LOAD_OPTION descriptor\n");

	efi_warn_once(FW_BUG "Using OptionalData as a workaround\n");



	*load_options = load_option_unpacked.optional_data;

	*load_options_size = load_option_unpacked.optional_data_size;

}



/*

 * Convert the unicode UEFI command line to ASCII to pass to kernel.

 * Size of memory allocated return in *cmd_line_len.
@@ -239,12 +335,15 @@ char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len) 
{

	const u16 *s2;

	unsigned long cmdline_addr = 0;

	int options_chars = efi_table_attr(image, load_options_size) / 2;

	int options_chars = efi_table_attr(image, load_options_size);

	const u16 *options = efi_table_attr(image, load_options);

	int options_bytes = 0, safe_options_bytes = 0;  /* UTF-8 bytes */

	bool in_quote = false;

	efi_status_t status;



	efi_apply_loadoptions_quirk((const void **)&options, &options_chars);

	options_chars /= sizeof(*options);



	if (options) {

		s2 = options;

		while (options_bytes < COMMAND_LINE_SIZE && options_chars--) {

drivers/firmware/efi/libstub/efistub.h

+31 −0
Original line number Diff line number Diff line
@@ -708,6 +708,35 @@ union efi_load_file_protocol { 
	} mixed_mode;

};



typedef struct {

	u32 attributes;

	u16 file_path_list_length;

	u8 variable_data[];

	// efi_char16_t description[];

	// efi_device_path_protocol_t file_path_list[];

	// u8 optional_data[];

} __packed efi_load_option_t;



#define EFI_LOAD_OPTION_ACTIVE		0x0001U

#define EFI_LOAD_OPTION_FORCE_RECONNECT	0x0002U

#define EFI_LOAD_OPTION_HIDDEN		0x0008U

#define EFI_LOAD_OPTION_CATEGORY	0x1f00U

#define   EFI_LOAD_OPTION_CATEGORY_BOOT	0x0000U

#define   EFI_LOAD_OPTION_CATEGORY_APP	0x0100U



#define EFI_LOAD_OPTION_BOOT_MASK \

	(EFI_LOAD_OPTION_ACTIVE|EFI_LOAD_OPTION_HIDDEN|EFI_LOAD_OPTION_CATEGORY)

#define EFI_LOAD_OPTION_MASK (EFI_LOAD_OPTION_FORCE_RECONNECT|EFI_LOAD_OPTION_BOOT_MASK)



typedef struct {

	u32 attributes;

	u16 file_path_list_length;

	const efi_char16_t *description;

	const efi_device_path_protocol_t *file_path_list;

	size_t optional_data_size;

	const void *optional_data;

} efi_load_option_unpacked_t;



void efi_pci_disable_bridge_busmaster(void);



typedef efi_status_t (*efi_exit_boot_map_processing)(
@@ -750,6 +779,8 @@ __printf(1, 2) int efi_printk(char const *fmt, ...); 


void efi_free(unsigned long size, unsigned long addr);



void efi_apply_loadoptions_quirk(const void **load_options, int *load_options_size);



char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len);



efi_status_t efi_get_memory_map(struct efi_boot_memmap *map);

drivers/firmware/efi/libstub/file.c

+4 −1
Original line number Diff line number Diff line
@@ -136,7 +136,7 @@ efi_status_t handle_cmdline_files(efi_loaded_image_t *image, 
				  unsigned long *load_size)

{

	const efi_char16_t *cmdline = image->load_options;

	int cmdline_len = image->load_options_size / 2;

	int cmdline_len = image->load_options_size;

	unsigned long efi_chunk_size = ULONG_MAX;

	efi_file_protocol_t *volume = NULL;

	efi_file_protocol_t *file;
@@ -148,6 +148,9 @@ efi_status_t handle_cmdline_files(efi_loaded_image_t *image, 
	if (!load_addr || !load_size)

		return EFI_INVALID_PARAMETER;



	efi_apply_loadoptions_quirk((const void **)&cmdline, &cmdline_len);

	cmdline_len /= sizeof(*cmdline);



	if (IS_ENABLED(CONFIG_X86) && !efi_nochunk)

		efi_chunk_size = EFI_READ_CHUNK_SIZE;

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