diff options
Diffstat (limited to 'drivers/firmware/efi/libstub/efi-stub-helper.c')
| -rw-r--r-- | drivers/firmware/efi/libstub/efi-stub-helper.c | 722 |
1 files changed, 722 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c new file mode 100644 index 0000000000..bfa30625f5 --- /dev/null +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -0,0 +1,722 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Helper functions used by the EFI stub on multiple + * architectures. This should be #included by the EFI stub + * implementation files. + * + * Copyright 2011 Intel Corporation; author Matt Fleming + */ + +#include <linux/stdarg.h> + +#include <linux/efi.h> +#include <linux/kernel.h> +#include <asm/efi.h> +#include <asm/setup.h> + +#include "efistub.h" + +bool efi_nochunk; +bool efi_nokaslr = !IS_ENABLED(CONFIG_RANDOMIZE_BASE); +bool efi_novamap; + +static bool efi_noinitrd; +static bool efi_nosoftreserve; +static bool efi_disable_pci_dma = IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA); + +bool __pure __efi_soft_reserve_enabled(void) +{ + return !efi_nosoftreserve; +} + +/** + * efi_parse_options() - Parse EFI command line options + * @cmdline: kernel command line + * + * Parse the ASCII string @cmdline for EFI options, denoted by the efi= + * option, e.g. efi=nochunk. + * + * It should be noted that efi= is parsed in two very different + * environments, first in the early boot environment of the EFI boot + * stub, and subsequently during the kernel boot. + * + * Return: status code + */ +efi_status_t efi_parse_options(char const *cmdline) +{ + size_t len; + efi_status_t status; + char *str, *buf; + + if (!cmdline) + return EFI_SUCCESS; + + len = strnlen(cmdline, COMMAND_LINE_SIZE - 1) + 1; + status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf); + if (status != EFI_SUCCESS) + return status; + + memcpy(buf, cmdline, len - 1); + buf[len - 1] = '\0'; + str = skip_spaces(buf); + + while (*str) { + char *param, *val; + + str = next_arg(str, ¶m, &val); + if (!val && !strcmp(param, "--")) + break; + + if (!strcmp(param, "nokaslr")) { + efi_nokaslr = true; + } else if (!strcmp(param, "quiet")) { + efi_loglevel = CONSOLE_LOGLEVEL_QUIET; + } else if (!strcmp(param, "noinitrd")) { + efi_noinitrd = true; + } else if (IS_ENABLED(CONFIG_X86_64) && !strcmp(param, "no5lvl")) { + efi_no5lvl = true; + } else if (!strcmp(param, "efi") && val) { + efi_nochunk = parse_option_str(val, "nochunk"); + efi_novamap |= parse_option_str(val, "novamap"); + + efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) && + parse_option_str(val, "nosoftreserve"); + + if (parse_option_str(val, "disable_early_pci_dma")) + efi_disable_pci_dma = true; + if (parse_option_str(val, "no_disable_early_pci_dma")) + efi_disable_pci_dma = false; + if (parse_option_str(val, "debug")) + efi_loglevel = CONSOLE_LOGLEVEL_DEBUG; + } else if (!strcmp(param, "video") && + val && strstarts(val, "efifb:")) { + efi_parse_option_graphics(val + strlen("efifb:")); + } + } + efi_bs_call(free_pool, buf); + 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, u32 *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; +} + +enum efistub_event { + EFISTUB_EVT_INITRD, + EFISTUB_EVT_LOAD_OPTIONS, + EFISTUB_EVT_COUNT, +}; + +#define STR_WITH_SIZE(s) sizeof(s), s + +static const struct { + u32 pcr_index; + u32 event_id; + u32 event_data_len; + u8 event_data[52]; +} events[] = { + [EFISTUB_EVT_INITRD] = { + 9, + INITRD_EVENT_TAG_ID, + STR_WITH_SIZE("Linux initrd") + }, + [EFISTUB_EVT_LOAD_OPTIONS] = { + 9, + LOAD_OPTIONS_EVENT_TAG_ID, + STR_WITH_SIZE("LOADED_IMAGE::LoadOptions") + }, +}; + +static efi_status_t efi_measure_tagged_event(unsigned long load_addr, + unsigned long load_size, + enum efistub_event event) +{ + efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID; + efi_tcg2_protocol_t *tcg2 = NULL; + efi_status_t status; + + efi_bs_call(locate_protocol, &tcg2_guid, NULL, (void **)&tcg2); + if (tcg2) { + struct efi_measured_event { + efi_tcg2_event_t event_data; + efi_tcg2_tagged_event_t tagged_event; + u8 tagged_event_data[]; + } *evt; + int size = sizeof(*evt) + events[event].event_data_len; + + status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size, + (void **)&evt); + if (status != EFI_SUCCESS) + goto fail; + + evt->event_data = (struct efi_tcg2_event){ + .event_size = size, + .event_header.header_size = sizeof(evt->event_data.event_header), + .event_header.header_version = EFI_TCG2_EVENT_HEADER_VERSION, + .event_header.pcr_index = events[event].pcr_index, + .event_header.event_type = EV_EVENT_TAG, + }; + + evt->tagged_event = (struct efi_tcg2_tagged_event){ + .tagged_event_id = events[event].event_id, + .tagged_event_data_size = events[event].event_data_len, + }; + + memcpy(evt->tagged_event_data, events[event].event_data, + events[event].event_data_len); + + status = efi_call_proto(tcg2, hash_log_extend_event, 0, + load_addr, load_size, &evt->event_data); + efi_bs_call(free_pool, evt); + + if (status != EFI_SUCCESS) + goto fail; + return EFI_SUCCESS; + } + + return EFI_UNSUPPORTED; +fail: + efi_warn("Failed to measure data for event %d: 0x%lx\n", event, status); + return status; +} + +/* + * 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. + */ +char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len) +{ + const efi_char16_t *options = efi_table_attr(image, load_options); + u32 options_size = efi_table_attr(image, load_options_size); + int options_bytes = 0, safe_options_bytes = 0; /* UTF-8 bytes */ + unsigned long cmdline_addr = 0; + const efi_char16_t *s2; + bool in_quote = false; + efi_status_t status; + u32 options_chars; + + if (options_size > 0) + efi_measure_tagged_event((unsigned long)options, options_size, + EFISTUB_EVT_LOAD_OPTIONS); + + efi_apply_loadoptions_quirk((const void **)&options, &options_size); + options_chars = options_size / sizeof(efi_char16_t); + + if (options) { + s2 = options; + while (options_bytes < COMMAND_LINE_SIZE && options_chars--) { + efi_char16_t c = *s2++; + + if (c < 0x80) { + if (c == L'\0' || c == L'\n') + break; + if (c == L'"') + in_quote = !in_quote; + else if (!in_quote && isspace((char)c)) + safe_options_bytes = options_bytes; + + options_bytes++; + continue; + } + + /* + * Get the number of UTF-8 bytes corresponding to a + * UTF-16 character. + * The first part handles everything in the BMP. + */ + options_bytes += 2 + (c >= 0x800); + /* + * Add one more byte for valid surrogate pairs. Invalid + * surrogates will be replaced with 0xfffd and take up + * only 3 bytes. + */ + if ((c & 0xfc00) == 0xd800) { + /* + * If the very last word is a high surrogate, + * we must ignore it since we can't access the + * low surrogate. + */ + if (!options_chars) { + options_bytes -= 3; + } else if ((*s2 & 0xfc00) == 0xdc00) { + options_bytes++; + options_chars--; + s2++; + } + } + } + if (options_bytes >= COMMAND_LINE_SIZE) { + options_bytes = safe_options_bytes; + efi_err("Command line is too long: truncated to %d bytes\n", + options_bytes); + } + } + + options_bytes++; /* NUL termination */ + + status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, options_bytes, + (void **)&cmdline_addr); + if (status != EFI_SUCCESS) + return NULL; + + snprintf((char *)cmdline_addr, options_bytes, "%.*ls", + options_bytes - 1, options); + + *cmd_line_len = options_bytes; + return (char *)cmdline_addr; +} + +/** + * efi_exit_boot_services() - Exit boot services + * @handle: handle of the exiting image + * @priv: argument to be passed to @priv_func + * @priv_func: function to process the memory map before exiting boot services + * + * Handle calling ExitBootServices according to the requirements set out by the + * spec. Obtains the current memory map, and returns that info after calling + * ExitBootServices. The client must specify a function to perform any + * processing of the memory map data prior to ExitBootServices. A client + * specific structure may be passed to the function via priv. The client + * function may be called multiple times. + * + * Return: status code + */ +efi_status_t efi_exit_boot_services(void *handle, void *priv, + efi_exit_boot_map_processing priv_func) +{ + struct efi_boot_memmap *map; + efi_status_t status; + + if (efi_disable_pci_dma) + efi_pci_disable_bridge_busmaster(); + + status = efi_get_memory_map(&map, true); + if (status != EFI_SUCCESS) + return status; + + status = priv_func(map, priv); + if (status != EFI_SUCCESS) { + efi_bs_call(free_pool, map); + return status; + } + + status = efi_bs_call(exit_boot_services, handle, map->map_key); + + if (status == EFI_INVALID_PARAMETER) { + /* + * The memory map changed between efi_get_memory_map() and + * exit_boot_services(). Per the UEFI Spec v2.6, Section 6.4: + * EFI_BOOT_SERVICES.ExitBootServices we need to get the + * updated map, and try again. The spec implies one retry + * should be sufficent, which is confirmed against the EDK2 + * implementation. Per the spec, we can only invoke + * get_memory_map() and exit_boot_services() - we cannot alloc + * so efi_get_memory_map() cannot be used, and we must reuse + * the buffer. For all practical purposes, the headroom in the + * buffer should account for any changes in the map so the call + * to get_memory_map() is expected to succeed here. + */ + map->map_size = map->buff_size; + status = efi_bs_call(get_memory_map, + &map->map_size, + &map->map, + &map->map_key, + &map->desc_size, + &map->desc_ver); + + /* exit_boot_services() was called, thus cannot free */ + if (status != EFI_SUCCESS) + return status; + + status = priv_func(map, priv); + /* exit_boot_services() was called, thus cannot free */ + if (status != EFI_SUCCESS) + return status; + + status = efi_bs_call(exit_boot_services, handle, map->map_key); + } + + return status; +} + +/** + * get_efi_config_table() - retrieve UEFI configuration table + * @guid: GUID of the configuration table to be retrieved + * Return: pointer to the configuration table or NULL + */ +void *get_efi_config_table(efi_guid_t guid) +{ + unsigned long tables = efi_table_attr(efi_system_table, tables); + int nr_tables = efi_table_attr(efi_system_table, nr_tables); + int i; + + for (i = 0; i < nr_tables; i++) { + efi_config_table_t *t = (void *)tables; + + if (efi_guidcmp(t->guid, guid) == 0) + return efi_table_attr(t, table); + + tables += efi_is_native() ? sizeof(efi_config_table_t) + : sizeof(efi_config_table_32_t); + } + return NULL; +} + +/* + * The LINUX_EFI_INITRD_MEDIA_GUID vendor media device path below provides a way + * for the firmware or bootloader to expose the initrd data directly to the stub + * via the trivial LoadFile2 protocol, which is defined in the UEFI spec, and is + * very easy to implement. It is a simple Linux initrd specific conduit between + * kernel and firmware, allowing us to put the EFI stub (being part of the + * kernel) in charge of where and when to load the initrd, while leaving it up + * to the firmware to decide whether it needs to expose its filesystem hierarchy + * via EFI protocols. + */ +static const struct { + struct efi_vendor_dev_path vendor; + struct efi_generic_dev_path end; +} __packed initrd_dev_path = { + { + { + EFI_DEV_MEDIA, + EFI_DEV_MEDIA_VENDOR, + sizeof(struct efi_vendor_dev_path), + }, + LINUX_EFI_INITRD_MEDIA_GUID + }, { + EFI_DEV_END_PATH, + EFI_DEV_END_ENTIRE, + sizeof(struct efi_generic_dev_path) + } +}; + +/** + * efi_load_initrd_dev_path() - load the initrd from the Linux initrd device path + * @initrd: pointer of struct to store the address where the initrd was loaded + * and the size of the loaded initrd + * @max: upper limit for the initrd memory allocation + * + * Return: + * * %EFI_SUCCESS if the initrd was loaded successfully, in which + * case @load_addr and @load_size are assigned accordingly + * * %EFI_NOT_FOUND if no LoadFile2 protocol exists on the initrd device path + * * %EFI_OUT_OF_RESOURCES if memory allocation failed + * * %EFI_LOAD_ERROR in all other cases + */ +static +efi_status_t efi_load_initrd_dev_path(struct linux_efi_initrd *initrd, + unsigned long max) +{ + efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID; + efi_device_path_protocol_t *dp; + efi_load_file2_protocol_t *lf2; + efi_handle_t handle; + efi_status_t status; + + dp = (efi_device_path_protocol_t *)&initrd_dev_path; + status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle); + if (status != EFI_SUCCESS) + return status; + + status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid, + (void **)&lf2); + if (status != EFI_SUCCESS) + return status; + + initrd->size = 0; + status = efi_call_proto(lf2, load_file, dp, false, &initrd->size, NULL); + if (status != EFI_BUFFER_TOO_SMALL) + return EFI_LOAD_ERROR; + + status = efi_allocate_pages(initrd->size, &initrd->base, max); + if (status != EFI_SUCCESS) + return status; + + status = efi_call_proto(lf2, load_file, dp, false, &initrd->size, + (void *)initrd->base); + if (status != EFI_SUCCESS) { + efi_free(initrd->size, initrd->base); + return EFI_LOAD_ERROR; + } + return EFI_SUCCESS; +} + +static +efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image, + struct linux_efi_initrd *initrd, + unsigned long soft_limit, + unsigned long hard_limit) +{ + if (image == NULL) + return EFI_UNSUPPORTED; + + return handle_cmdline_files(image, L"initrd=", sizeof(L"initrd=") - 2, + soft_limit, hard_limit, + &initrd->base, &initrd->size); +} + +/** + * efi_load_initrd() - Load initial RAM disk + * @image: EFI loaded image protocol + * @soft_limit: preferred address for loading the initrd + * @hard_limit: upper limit address for loading the initrd + * + * Return: status code + */ +efi_status_t efi_load_initrd(efi_loaded_image_t *image, + unsigned long soft_limit, + unsigned long hard_limit, + const struct linux_efi_initrd **out) +{ + efi_guid_t tbl_guid = LINUX_EFI_INITRD_MEDIA_GUID; + efi_status_t status = EFI_SUCCESS; + struct linux_efi_initrd initrd, *tbl; + + if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD) || efi_noinitrd) + return EFI_SUCCESS; + + status = efi_load_initrd_dev_path(&initrd, hard_limit); + if (status == EFI_SUCCESS) { + efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n"); + if (initrd.size > 0 && + efi_measure_tagged_event(initrd.base, initrd.size, + EFISTUB_EVT_INITRD) == EFI_SUCCESS) + efi_info("Measured initrd data into PCR 9\n"); + } else if (status == EFI_NOT_FOUND) { + status = efi_load_initrd_cmdline(image, &initrd, soft_limit, + hard_limit); + /* command line loader disabled or no initrd= passed? */ + if (status == EFI_UNSUPPORTED || status == EFI_NOT_READY) + return EFI_SUCCESS; + if (status == EFI_SUCCESS) + efi_info("Loaded initrd from command line option\n"); + } + if (status != EFI_SUCCESS) + goto failed; + + status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(initrd), + (void **)&tbl); + if (status != EFI_SUCCESS) + goto free_initrd; + + *tbl = initrd; + status = efi_bs_call(install_configuration_table, &tbl_guid, tbl); + if (status != EFI_SUCCESS) + goto free_tbl; + + if (out) + *out = tbl; + return EFI_SUCCESS; + +free_tbl: + efi_bs_call(free_pool, tbl); +free_initrd: + efi_free(initrd.size, initrd.base); +failed: + efi_err("Failed to load initrd: 0x%lx\n", status); + return status; +} + +/** + * efi_wait_for_key() - Wait for key stroke + * @usec: number of microseconds to wait for key stroke + * @key: key entered + * + * Wait for up to @usec microseconds for a key stroke. + * + * Return: status code, EFI_SUCCESS if key received + */ +efi_status_t efi_wait_for_key(unsigned long usec, efi_input_key_t *key) +{ + efi_event_t events[2], timer; + unsigned long index; + efi_simple_text_input_protocol_t *con_in; + efi_status_t status; + + con_in = efi_table_attr(efi_system_table, con_in); + if (!con_in) + return EFI_UNSUPPORTED; + efi_set_event_at(events, 0, efi_table_attr(con_in, wait_for_key)); + + status = efi_bs_call(create_event, EFI_EVT_TIMER, 0, NULL, NULL, &timer); + if (status != EFI_SUCCESS) + return status; + + status = efi_bs_call(set_timer, timer, EfiTimerRelative, + EFI_100NSEC_PER_USEC * usec); + if (status != EFI_SUCCESS) + return status; + efi_set_event_at(events, 1, timer); + + status = efi_bs_call(wait_for_event, 2, events, &index); + if (status == EFI_SUCCESS) { + if (index == 0) + status = efi_call_proto(con_in, read_keystroke, key); + else + status = EFI_TIMEOUT; + } + + efi_bs_call(close_event, timer); + + return status; +} + +/** + * efi_remap_image - Remap a loaded image with the appropriate permissions + * for code and data + * + * @image_base: the base of the image in memory + * @alloc_size: the size of the area in memory occupied by the image + * @code_size: the size of the leading part of the image containing code + * and read-only data + * + * efi_remap_image() uses the EFI memory attribute protocol to remap the code + * region of the loaded image read-only/executable, and the remainder + * read-write/non-executable. The code region is assumed to start at the base + * of the image, and will therefore cover the PE/COFF header as well. + */ +void efi_remap_image(unsigned long image_base, unsigned alloc_size, + unsigned long code_size) +{ + efi_guid_t guid = EFI_MEMORY_ATTRIBUTE_PROTOCOL_GUID; + efi_memory_attribute_protocol_t *memattr; + efi_status_t status; + u64 attr; + + /* + * If the firmware implements the EFI_MEMORY_ATTRIBUTE_PROTOCOL, let's + * invoke it to remap the text/rodata region of the decompressed image + * as read-only and the data/bss region as non-executable. + */ + status = efi_bs_call(locate_protocol, &guid, NULL, (void **)&memattr); + if (status != EFI_SUCCESS) + return; + + // Get the current attributes for the entire region + status = memattr->get_memory_attributes(memattr, image_base, + alloc_size, &attr); + if (status != EFI_SUCCESS) { + efi_warn("Failed to retrieve memory attributes for image region: 0x%lx\n", + status); + return; + } + + // Mark the code region as read-only + status = memattr->set_memory_attributes(memattr, image_base, code_size, + EFI_MEMORY_RO); + if (status != EFI_SUCCESS) { + efi_warn("Failed to remap code region read-only\n"); + return; + } + + // If the entire region was already mapped as non-exec, clear the + // attribute from the code region. Otherwise, set it on the data + // region. + if (attr & EFI_MEMORY_XP) { + status = memattr->clear_memory_attributes(memattr, image_base, + code_size, + EFI_MEMORY_XP); + if (status != EFI_SUCCESS) + efi_warn("Failed to remap code region executable\n"); + } else { + status = memattr->set_memory_attributes(memattr, + image_base + code_size, + alloc_size - code_size, + EFI_MEMORY_XP); + if (status != EFI_SUCCESS) + efi_warn("Failed to remap data region non-executable\n"); + } +} |