723 строки
18 KiB
C
723 строки
18 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Originally from efivars.c
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*
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* Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
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* Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
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*/
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#include <linux/capability.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/smp.h>
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#include <linux/efi.h>
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#include <linux/device.h>
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#include <linux/slab.h>
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#include <linux/ctype.h>
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#include <linux/ucs2_string.h>
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#include "internal.h"
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MODULE_IMPORT_NS(EFIVAR);
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static bool
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validate_device_path(efi_char16_t *var_name, int match, u8 *buffer,
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unsigned long len)
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{
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struct efi_generic_dev_path *node;
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int offset = 0;
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node = (struct efi_generic_dev_path *)buffer;
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if (len < sizeof(*node))
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return false;
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while (offset <= len - sizeof(*node) &&
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node->length >= sizeof(*node) &&
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node->length <= len - offset) {
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offset += node->length;
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if ((node->type == EFI_DEV_END_PATH ||
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node->type == EFI_DEV_END_PATH2) &&
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node->sub_type == EFI_DEV_END_ENTIRE)
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return true;
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node = (struct efi_generic_dev_path *)(buffer + offset);
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}
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/*
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* If we're here then either node->length pointed past the end
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* of the buffer or we reached the end of the buffer without
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* finding a device path end node.
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*/
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return false;
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}
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static bool
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validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer,
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unsigned long len)
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{
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/* An array of 16-bit integers */
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if ((len % 2) != 0)
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return false;
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return true;
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}
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static bool
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validate_load_option(efi_char16_t *var_name, int match, u8 *buffer,
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unsigned long len)
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{
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u16 filepathlength;
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int i, desclength = 0, namelen;
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namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN);
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/* Either "Boot" or "Driver" followed by four digits of hex */
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for (i = match; i < match+4; i++) {
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if (var_name[i] > 127 ||
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hex_to_bin(var_name[i] & 0xff) < 0)
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return true;
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}
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/* Reject it if there's 4 digits of hex and then further content */
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if (namelen > match + 4)
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return false;
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/* A valid entry must be at least 8 bytes */
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if (len < 8)
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return false;
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filepathlength = buffer[4] | buffer[5] << 8;
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/*
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* There's no stored length for the description, so it has to be
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* found by hand
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*/
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desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
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/* Each boot entry must have a descriptor */
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if (!desclength)
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return false;
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/*
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* If the sum of the length of the description, the claimed filepath
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* length and the original header are greater than the length of the
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* variable, it's malformed
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*/
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if ((desclength + filepathlength + 6) > len)
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return false;
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/*
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* And, finally, check the filepath
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*/
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return validate_device_path(var_name, match, buffer + desclength + 6,
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filepathlength);
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}
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static bool
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validate_uint16(efi_char16_t *var_name, int match, u8 *buffer,
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unsigned long len)
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{
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/* A single 16-bit integer */
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if (len != 2)
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return false;
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return true;
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}
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static bool
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validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer,
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unsigned long len)
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{
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int i;
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for (i = 0; i < len; i++) {
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if (buffer[i] > 127)
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return false;
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if (buffer[i] == 0)
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return true;
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}
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return false;
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}
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struct variable_validate {
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efi_guid_t vendor;
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char *name;
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bool (*validate)(efi_char16_t *var_name, int match, u8 *data,
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unsigned long len);
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};
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/*
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* This is the list of variables we need to validate, as well as the
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* whitelist for what we think is safe not to default to immutable.
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*
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* If it has a validate() method that's not NULL, it'll go into the
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* validation routine. If not, it is assumed valid, but still used for
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* whitelisting.
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*
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* Note that it's sorted by {vendor,name}, but globbed names must come after
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* any other name with the same prefix.
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*/
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static const struct variable_validate variable_validate[] = {
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{ EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 },
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{ EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order },
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{ EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option },
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{ EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order },
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{ EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option },
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{ EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path },
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{ EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path },
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{ EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path },
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{ EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path },
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{ EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path },
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{ EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path },
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{ EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string },
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{ EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL },
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{ EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string },
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{ EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 },
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{ LINUX_EFI_CRASH_GUID, "*", NULL },
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{ NULL_GUID, "", NULL },
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};
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/*
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* Check if @var_name matches the pattern given in @match_name.
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*
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* @var_name: an array of @len non-NUL characters.
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* @match_name: a NUL-terminated pattern string, optionally ending in "*". A
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* final "*" character matches any trailing characters @var_name,
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* including the case when there are none left in @var_name.
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* @match: on output, the number of non-wildcard characters in @match_name
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* that @var_name matches, regardless of the return value.
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* @return: whether @var_name fully matches @match_name.
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*/
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static bool
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variable_matches(const char *var_name, size_t len, const char *match_name,
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int *match)
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{
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for (*match = 0; ; (*match)++) {
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char c = match_name[*match];
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switch (c) {
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case '*':
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/* Wildcard in @match_name means we've matched. */
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return true;
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case '\0':
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/* @match_name has ended. Has @var_name too? */
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return (*match == len);
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default:
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/*
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* We've reached a non-wildcard char in @match_name.
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* Continue only if there's an identical character in
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* @var_name.
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*/
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if (*match < len && c == var_name[*match])
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continue;
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return false;
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}
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}
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}
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bool
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efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
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unsigned long data_size)
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{
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int i;
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unsigned long utf8_size;
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u8 *utf8_name;
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utf8_size = ucs2_utf8size(var_name);
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utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL);
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if (!utf8_name)
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return false;
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ucs2_as_utf8(utf8_name, var_name, utf8_size);
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utf8_name[utf8_size] = '\0';
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for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
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const char *name = variable_validate[i].name;
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int match = 0;
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if (efi_guidcmp(vendor, variable_validate[i].vendor))
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continue;
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if (variable_matches(utf8_name, utf8_size+1, name, &match)) {
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if (variable_validate[i].validate == NULL)
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break;
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kfree(utf8_name);
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return variable_validate[i].validate(var_name, match,
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data, data_size);
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}
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}
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kfree(utf8_name);
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return true;
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}
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bool
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efivar_variable_is_removable(efi_guid_t vendor, const char *var_name,
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size_t len)
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{
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int i;
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bool found = false;
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int match = 0;
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/*
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* Check if our variable is in the validated variables list
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*/
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for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
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if (efi_guidcmp(variable_validate[i].vendor, vendor))
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continue;
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if (variable_matches(var_name, len,
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variable_validate[i].name, &match)) {
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found = true;
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break;
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}
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}
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/*
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* If it's in our list, it is removable.
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*/
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return found;
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}
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static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor,
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struct list_head *head)
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{
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struct efivar_entry *entry, *n;
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unsigned long strsize1, strsize2;
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bool found = false;
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strsize1 = ucs2_strsize(variable_name, 1024);
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list_for_each_entry_safe(entry, n, head, list) {
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strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
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if (strsize1 == strsize2 &&
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!memcmp(variable_name, &(entry->var.VariableName),
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strsize2) &&
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!efi_guidcmp(entry->var.VendorGuid,
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*vendor)) {
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found = true;
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break;
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}
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}
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return found;
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}
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/*
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* Returns the size of variable_name, in bytes, including the
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* terminating NULL character, or variable_name_size if no NULL
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* character is found among the first variable_name_size bytes.
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*/
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static unsigned long var_name_strnsize(efi_char16_t *variable_name,
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unsigned long variable_name_size)
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{
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unsigned long len;
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efi_char16_t c;
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/*
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* The variable name is, by definition, a NULL-terminated
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* string, so make absolutely sure that variable_name_size is
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* the value we expect it to be. If not, return the real size.
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*/
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for (len = 2; len <= variable_name_size; len += sizeof(c)) {
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c = variable_name[(len / sizeof(c)) - 1];
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if (!c)
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break;
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}
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return min(len, variable_name_size);
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}
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/*
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* Print a warning when duplicate EFI variables are encountered and
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* disable the sysfs workqueue since the firmware is buggy.
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*/
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static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
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unsigned long len16)
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{
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size_t i, len8 = len16 / sizeof(efi_char16_t);
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char *str8;
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str8 = kzalloc(len8, GFP_KERNEL);
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if (!str8)
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return;
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for (i = 0; i < len8; i++)
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str8[i] = str16[i];
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printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
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str8, vendor_guid);
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kfree(str8);
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}
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/**
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* efivar_init - build the initial list of EFI variables
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* @func: callback function to invoke for every variable
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* @data: function-specific data to pass to @func
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* @duplicates: error if we encounter duplicates on @head?
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* @head: initialised head of variable list
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*
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* Get every EFI variable from the firmware and invoke @func. @func
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* should call efivar_entry_add() to build the list of variables.
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*
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* Returns 0 on success, or a kernel error code on failure.
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*/
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int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
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void *data, bool duplicates, struct list_head *head)
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{
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unsigned long variable_name_size = 1024;
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efi_char16_t *variable_name;
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efi_status_t status;
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efi_guid_t vendor_guid;
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int err = 0;
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variable_name = kzalloc(variable_name_size, GFP_KERNEL);
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if (!variable_name) {
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printk(KERN_ERR "efivars: Memory allocation failed.\n");
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return -ENOMEM;
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}
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err = efivar_lock();
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if (err)
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goto free;
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/*
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* Per EFI spec, the maximum storage allocated for both
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* the variable name and variable data is 1024 bytes.
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*/
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do {
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variable_name_size = 1024;
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status = efivar_get_next_variable(&variable_name_size,
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variable_name,
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&vendor_guid);
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switch (status) {
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case EFI_SUCCESS:
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variable_name_size = var_name_strnsize(variable_name,
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variable_name_size);
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/*
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* Some firmware implementations return the
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* same variable name on multiple calls to
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* get_next_variable(). Terminate the loop
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* immediately as there is no guarantee that
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* we'll ever see a different variable name,
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* and may end up looping here forever.
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*/
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if (duplicates &&
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variable_is_present(variable_name, &vendor_guid,
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head)) {
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dup_variable_bug(variable_name, &vendor_guid,
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variable_name_size);
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status = EFI_NOT_FOUND;
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} else {
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err = func(variable_name, vendor_guid,
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variable_name_size, data);
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if (err)
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status = EFI_NOT_FOUND;
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}
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break;
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case EFI_UNSUPPORTED:
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err = -EOPNOTSUPP;
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status = EFI_NOT_FOUND;
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break;
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case EFI_NOT_FOUND:
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break;
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default:
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printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
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status);
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status = EFI_NOT_FOUND;
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break;
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}
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} while (status != EFI_NOT_FOUND);
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efivar_unlock();
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free:
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kfree(variable_name);
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return err;
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}
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/**
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* efivar_entry_add - add entry to variable list
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* @entry: entry to add to list
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* @head: list head
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*
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* Returns 0 on success, or a kernel error code on failure.
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*/
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int efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
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{
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int err;
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err = efivar_lock();
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if (err)
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return err;
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list_add(&entry->list, head);
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efivar_unlock();
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return 0;
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}
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/**
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* __efivar_entry_add - add entry to variable list
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* @entry: entry to add to list
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* @head: list head
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*/
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void __efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
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{
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list_add(&entry->list, head);
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}
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/**
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* efivar_entry_remove - remove entry from variable list
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* @entry: entry to remove from list
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*
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* Returns 0 on success, or a kernel error code on failure.
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*/
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void efivar_entry_remove(struct efivar_entry *entry)
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{
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list_del(&entry->list);
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}
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/*
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* efivar_entry_list_del_unlock - remove entry from variable list
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* @entry: entry to remove
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*
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* Remove @entry from the variable list and release the list lock.
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*
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* NOTE: slightly weird locking semantics here - we expect to be
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* called with the efivars lock already held, and we release it before
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* returning. This is because this function is usually called after
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* set_variable() while the lock is still held.
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*/
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static void efivar_entry_list_del_unlock(struct efivar_entry *entry)
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{
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list_del(&entry->list);
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efivar_unlock();
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}
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/**
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* efivar_entry_delete - delete variable and remove entry from list
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* @entry: entry containing variable to delete
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*
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* Delete the variable from the firmware and remove @entry from the
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* variable list. It is the caller's responsibility to free @entry
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* once we return.
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*
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* Returns 0 on success, -EINTR if we can't grab the semaphore,
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* converted EFI status code if set_variable() fails.
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*/
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int efivar_entry_delete(struct efivar_entry *entry)
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{
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efi_status_t status;
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int err;
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err = efivar_lock();
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if (err)
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return err;
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status = efivar_set_variable_locked(entry->var.VariableName,
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&entry->var.VendorGuid,
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0, 0, NULL, false);
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if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) {
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efivar_unlock();
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return efi_status_to_err(status);
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}
|
|
|
|
efivar_entry_list_del_unlock(entry);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* efivar_entry_size - obtain the size of a variable
|
|
* @entry: entry for this variable
|
|
* @size: location to store the variable's size
|
|
*/
|
|
int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
|
|
{
|
|
efi_status_t status;
|
|
int err;
|
|
|
|
*size = 0;
|
|
|
|
err = efivar_lock();
|
|
if (err)
|
|
return err;
|
|
|
|
status = efivar_get_variable(entry->var.VariableName,
|
|
&entry->var.VendorGuid, NULL, size, NULL);
|
|
efivar_unlock();
|
|
|
|
if (status != EFI_BUFFER_TOO_SMALL)
|
|
return efi_status_to_err(status);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* __efivar_entry_get - call get_variable()
|
|
* @entry: read data for this variable
|
|
* @attributes: variable attributes
|
|
* @size: size of @data buffer
|
|
* @data: buffer to store variable data
|
|
*
|
|
* The caller MUST call efivar_entry_iter_begin() and
|
|
* efivar_entry_iter_end() before and after the invocation of this
|
|
* function, respectively.
|
|
*/
|
|
int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
|
|
unsigned long *size, void *data)
|
|
{
|
|
efi_status_t status;
|
|
|
|
status = efivar_get_variable(entry->var.VariableName,
|
|
&entry->var.VendorGuid,
|
|
attributes, size, data);
|
|
|
|
return efi_status_to_err(status);
|
|
}
|
|
|
|
/**
|
|
* efivar_entry_get - call get_variable()
|
|
* @entry: read data for this variable
|
|
* @attributes: variable attributes
|
|
* @size: size of @data buffer
|
|
* @data: buffer to store variable data
|
|
*/
|
|
int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
|
|
unsigned long *size, void *data)
|
|
{
|
|
int err;
|
|
|
|
err = efivar_lock();
|
|
if (err)
|
|
return err;
|
|
err = __efivar_entry_get(entry, attributes, size, data);
|
|
efivar_unlock();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* efivar_entry_set_get_size - call set_variable() and get new size (atomic)
|
|
* @entry: entry containing variable to set and get
|
|
* @attributes: attributes of variable to be written
|
|
* @size: size of data buffer
|
|
* @data: buffer containing data to write
|
|
* @set: did the set_variable() call succeed?
|
|
*
|
|
* This is a pretty special (complex) function. See efivarfs_file_write().
|
|
*
|
|
* Atomically call set_variable() for @entry and if the call is
|
|
* successful, return the new size of the variable from get_variable()
|
|
* in @size. The success of set_variable() is indicated by @set.
|
|
*
|
|
* Returns 0 on success, -EINVAL if the variable data is invalid,
|
|
* -ENOSPC if the firmware does not have enough available space, or a
|
|
* converted EFI status code if either of set_variable() or
|
|
* get_variable() fail.
|
|
*
|
|
* If the EFI variable does not exist when calling set_variable()
|
|
* (EFI_NOT_FOUND), @entry is removed from the variable list.
|
|
*/
|
|
int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
|
|
unsigned long *size, void *data, bool *set)
|
|
{
|
|
efi_char16_t *name = entry->var.VariableName;
|
|
efi_guid_t *vendor = &entry->var.VendorGuid;
|
|
efi_status_t status;
|
|
int err;
|
|
|
|
*set = false;
|
|
|
|
if (efivar_validate(*vendor, name, data, *size) == false)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* The lock here protects the get_variable call, the conditional
|
|
* set_variable call, and removal of the variable from the efivars
|
|
* list (in the case of an authenticated delete).
|
|
*/
|
|
err = efivar_lock();
|
|
if (err)
|
|
return err;
|
|
|
|
status = efivar_set_variable_locked(name, vendor, attributes, *size,
|
|
data, false);
|
|
if (status != EFI_SUCCESS) {
|
|
err = efi_status_to_err(status);
|
|
goto out;
|
|
}
|
|
|
|
*set = true;
|
|
|
|
/*
|
|
* Writing to the variable may have caused a change in size (which
|
|
* could either be an append or an overwrite), or the variable to be
|
|
* deleted. Perform a GetVariable() so we can tell what actually
|
|
* happened.
|
|
*/
|
|
*size = 0;
|
|
status = efivar_get_variable(entry->var.VariableName,
|
|
&entry->var.VendorGuid,
|
|
NULL, size, NULL);
|
|
|
|
if (status == EFI_NOT_FOUND)
|
|
efivar_entry_list_del_unlock(entry);
|
|
else
|
|
efivar_unlock();
|
|
|
|
if (status && status != EFI_BUFFER_TOO_SMALL)
|
|
return efi_status_to_err(status);
|
|
|
|
return 0;
|
|
|
|
out:
|
|
efivar_unlock();
|
|
return err;
|
|
|
|
}
|
|
|
|
/**
|
|
* efivar_entry_iter - iterate over variable list
|
|
* @func: callback function
|
|
* @head: head of variable list
|
|
* @data: function-specific data to pass to callback
|
|
*
|
|
* Iterate over the list of EFI variables and call @func with every
|
|
* entry on the list. It is safe for @func to remove entries in the
|
|
* list via efivar_entry_delete() while iterating.
|
|
*
|
|
* Some notes for the callback function:
|
|
* - a non-zero return value indicates an error and terminates the loop
|
|
* - @func is called from atomic context
|
|
*/
|
|
int efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
|
|
struct list_head *head, void *data)
|
|
{
|
|
struct efivar_entry *entry, *n;
|
|
int err = 0;
|
|
|
|
err = efivar_lock();
|
|
if (err)
|
|
return err;
|
|
|
|
list_for_each_entry_safe(entry, n, head, list) {
|
|
err = func(entry, data);
|
|
if (err)
|
|
break;
|
|
}
|
|
efivar_unlock();
|
|
|
|
return err;
|
|
}
|