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author | Arvind Sankar <nivedita@alum.mit.edu> | 2020-09-14 17:35:35 -0400 |
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committer | Ard Biesheuvel <ardb@kernel.org> | 2020-09-17 10:19:53 +0300 |
commit | 4a568ce29d3f48df95919f82a80e4b9be7ea0dc1 (patch) | |
tree | 019bd16303a6cf40bcec89adc4398e6df41a61a8 /drivers/firmware/efi/libstub/efi-stub-helper.c | |
parent | efi/libstub: Add efi_warn and *_once logging helpers (diff) | |
download | linux-4a568ce29d3f48df95919f82a80e4b9be7ea0dc1.tar.gz linux-4a568ce29d3f48df95919f82a80e4b9be7ea0dc1.tar.bz2 linux-4a568ce29d3f48df95919f82a80e4b9be7ea0dc1.zip |
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: Arvind Sankar <nivedita@alum.mit.edu>
Reported-by: Jacobo 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: Ard Biesheuvel <ardb@kernel.org>
Diffstat (limited to 'drivers/firmware/efi/libstub/efi-stub-helper.c')
-rw-r--r-- | drivers/firmware/efi/libstub/efi-stub-helper.c | 101 |
1 files changed, 100 insertions, 1 deletions
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index 6bca70bbb43d..4dbf04cc8930 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -231,6 +231,102 @@ efi_status_t efi_parse_options(char const *cmdline) } /* + * 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. * Returns NULL on error. @@ -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--) { |