diff options
Diffstat (limited to 'lib/efi_loader/efi_variable.c')
| -rw-r--r-- | lib/efi_loader/efi_variable.c | 335 |
1 files changed, 335 insertions, 0 deletions
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c new file mode 100644 index 0000000000..6c177da3a6 --- /dev/null +++ b/lib/efi_loader/efi_variable.c @@ -0,0 +1,335 @@ +/* + * EFI utils + * + * Copyright (c) 2017 Rob Clark + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include <malloc.h> +#include <charset.h> +#include <efi_loader.h> + +#define READ_ONLY BIT(31) + +/* + * Mapping between EFI variables and u-boot variables: + * + * efi_$guid_$varname = {attributes}(type)value + * + * For example: + * + * efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported= + * "{ro,boot,run}(blob)0000000000000000" + * efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder= + * "(blob)00010000" + * + * The attributes are a comma separated list of these possible + * attributes: + * + * + ro - read-only + * + boot - boot-services access + * + run - runtime access + * + * NOTE: with current implementation, no variables are available after + * ExitBootServices, and all are persisted (if possible). + * + * If not specified, the attributes default to "{boot}". + * + * The required type is one of: + * + * + utf8 - raw utf8 string + * + blob - arbitrary length hex string + * + * Maybe a utf16 type would be useful to for a string value to be auto + * converted to utf16? + */ + +#define MAX_VAR_NAME 31 +#define MAX_NATIVE_VAR_NAME \ + (strlen("efi_xxxxxxxx-xxxx-xxxx-xxxxxxxxxxxxxxxx_") + \ + (MAX_VAR_NAME * MAX_UTF8_PER_UTF16)) + +static int hex(unsigned char ch) +{ + if (ch >= 'a' && ch <= 'f') + return ch-'a'+10; + if (ch >= '0' && ch <= '9') + return ch-'0'; + if (ch >= 'A' && ch <= 'F') + return ch-'A'+10; + return -1; +} + +static const char *hex2mem(u8 *mem, const char *hexstr, int count) +{ + memset(mem, 0, count/2); + + do { + int nibble; + + *mem = 0; + + if (!count || !*hexstr) + break; + + nibble = hex(*hexstr); + if (nibble < 0) + break; + + *mem = nibble; + count--; + hexstr++; + + if (!count || !*hexstr) + break; + + nibble = hex(*hexstr); + if (nibble < 0) + break; + + *mem = (*mem << 4) | nibble; + count--; + hexstr++; + mem++; + + } while (1); + + if (*hexstr) + return hexstr; + + return NULL; +} + +static char *mem2hex(char *hexstr, const u8 *mem, int count) +{ + static const char hexchars[] = "0123456789abcdef"; + + while (count-- > 0) { + u8 ch = *mem++; + *hexstr++ = hexchars[ch >> 4]; + *hexstr++ = hexchars[ch & 0xf]; + } + + return hexstr; +} + +static efi_status_t efi_to_native(char *native, s16 *variable_name, + efi_guid_t *vendor) +{ + size_t len; + + len = utf16_strlen((u16 *)variable_name); + if (len >= MAX_VAR_NAME) + return EFI_DEVICE_ERROR; + + native += sprintf(native, "efi_%pUl_", vendor); + native = (char *)utf16_to_utf8((u8 *)native, (u16 *)variable_name, len); + *native = '\0'; + + return EFI_SUCCESS; +} + +static const char *prefix(const char *str, const char *prefix) +{ + size_t n = strlen(prefix); + if (!strncmp(prefix, str, n)) + return str + n; + return NULL; +} + +/* parse attributes part of variable value, if present: */ +static const char *parse_attr(const char *str, u32 *attrp) +{ + u32 attr = 0; + char sep = '{'; + + if (*str != '{') { + *attrp = EFI_VARIABLE_BOOTSERVICE_ACCESS; + return str; + } + + while (*str == sep) { + const char *s; + + str++; + + if ((s = prefix(str, "ro"))) { + attr |= READ_ONLY; + } else if ((s = prefix(str, "boot"))) { + attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS; + } else if ((s = prefix(str, "run"))) { + attr |= EFI_VARIABLE_RUNTIME_ACCESS; + } else { + printf("invalid attribute: %s\n", str); + break; + } + + str = s; + sep = ','; + } + + str++; + + *attrp = attr; + + return str; +} + +/* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#GetVariable.28.29 */ +efi_status_t EFIAPI efi_get_variable(s16 *variable_name, + efi_guid_t *vendor, u32 *attributes, + unsigned long *data_size, void *data) +{ + char native_name[MAX_NATIVE_VAR_NAME + 1]; + efi_status_t ret; + unsigned long in_size; + const char *val, *s; + u32 attr; + + EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes, + data_size, data); + + if (!variable_name || !vendor || !data_size) + return EFI_EXIT(EFI_INVALID_PARAMETER); + + ret = efi_to_native(native_name, variable_name, vendor); + if (ret) + return EFI_EXIT(ret); + + debug("%s: get '%s'\n", __func__, native_name); + + val = env_get(native_name); + if (!val) + return EFI_EXIT(EFI_NOT_FOUND); + + val = parse_attr(val, &attr); + + in_size = *data_size; + + if ((s = prefix(val, "(blob)"))) { + unsigned len = strlen(s); + + /* two characters per byte: */ + len = DIV_ROUND_UP(len, 2); + *data_size = len; + + if (in_size < len) + return EFI_EXIT(EFI_BUFFER_TOO_SMALL); + + if (!data) + return EFI_EXIT(EFI_INVALID_PARAMETER); + + if (hex2mem(data, s, len * 2)) + return EFI_EXIT(EFI_DEVICE_ERROR); + + debug("%s: got value: \"%s\"\n", __func__, s); + } else if ((s = prefix(val, "(utf8)"))) { + unsigned len = strlen(s) + 1; + + *data_size = len; + + if (in_size < len) + return EFI_EXIT(EFI_BUFFER_TOO_SMALL); + + if (!data) + return EFI_EXIT(EFI_INVALID_PARAMETER); + + memcpy(data, s, len); + ((char *)data)[len] = '\0'; + + debug("%s: got value: \"%s\"\n", __func__, (char *)data); + } else { + debug("%s: invalid value: '%s'\n", __func__, val); + return EFI_EXIT(EFI_DEVICE_ERROR); + } + + if (attributes) + *attributes = attr & EFI_VARIABLE_MASK; + + return EFI_EXIT(EFI_SUCCESS); +} + +/* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#GetNextVariableName.28.29 */ +efi_status_t EFIAPI efi_get_next_variable( + unsigned long *variable_name_size, + s16 *variable_name, efi_guid_t *vendor) +{ + EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor); + + return EFI_EXIT(EFI_DEVICE_ERROR); +} + +/* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#SetVariable.28.29 */ +efi_status_t EFIAPI efi_set_variable(s16 *variable_name, + efi_guid_t *vendor, u32 attributes, + unsigned long data_size, void *data) +{ + char native_name[MAX_NATIVE_VAR_NAME + 1]; + efi_status_t ret = EFI_SUCCESS; + char *val, *s; + u32 attr; + + EFI_ENTRY("\"%ls\" %pUl %x %lu %p", variable_name, vendor, attributes, + data_size, data); + + if (!variable_name || !vendor) + return EFI_EXIT(EFI_INVALID_PARAMETER); + + ret = efi_to_native(native_name, variable_name, vendor); + if (ret) + return EFI_EXIT(ret); + +#define ACCESS_ATTR (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS) + + if ((data_size == 0) || !(attributes & ACCESS_ATTR)) { + /* delete the variable: */ + env_set(native_name, NULL); + return EFI_EXIT(EFI_SUCCESS); + } + + val = env_get(native_name); + if (val) { + parse_attr(val, &attr); + + if (attr & READ_ONLY) + return EFI_EXIT(EFI_WRITE_PROTECTED); + } + + val = malloc(2 * data_size + strlen("{ro,run,boot}(blob)") + 1); + if (!val) + return EFI_EXIT(EFI_OUT_OF_RESOURCES); + + s = val; + + /* store attributes: */ + attributes &= (EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS); + s += sprintf(s, "{"); + while (attributes) { + u32 attr = 1 << (ffs(attributes) - 1); + + if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS) + s += sprintf(s, "boot"); + else if (attr == EFI_VARIABLE_RUNTIME_ACCESS) + s += sprintf(s, "run"); + + attributes &= ~attr; + if (attributes) + s += sprintf(s, ","); + } + s += sprintf(s, "}"); + + /* store payload: */ + s += sprintf(s, "(blob)"); + s = mem2hex(s, data, data_size); + *s = '\0'; + + debug("%s: setting: %s=%s\n", __func__, native_name, val); + + if (env_set(native_name, val)) + ret = EFI_DEVICE_ERROR; + + free(val); + + return EFI_EXIT(ret); +} |