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- // SPDX-License-Identifier: GPL-2.0+
- /*
- * Originally from efivars.c
- *
- * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
- * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
- */
- #include <linux/capability.h>
- #include <linux/types.h>
- #include <linux/errno.h>
- #include <linux/init.h>
- #include <linux/mm.h>
- #include <linux/module.h>
- #include <linux/string.h>
- #include <linux/smp.h>
- #include <linux/efi.h>
- #include <linux/sysfs.h>
- #include <linux/device.h>
- #include <linux/slab.h>
- #include <linux/ctype.h>
- #include <linux/ucs2_string.h>
- /* Private pointer to registered efivars */
- static struct efivars *__efivars;
- /*
- * efivars_lock protects three things:
- * 1) efivarfs_list and efivars_sysfs_list
- * 2) ->ops calls
- * 3) (un)registration of __efivars
- */
- static DEFINE_SEMAPHORE(efivars_lock);
- static bool
- validate_device_path(efi_char16_t *var_name, int match, u8 *buffer,
- unsigned long len)
- {
- struct efi_generic_dev_path *node;
- int offset = 0;
- node = (struct efi_generic_dev_path *)buffer;
- if (len < sizeof(*node))
- return false;
- while (offset <= len - sizeof(*node) &&
- node->length >= sizeof(*node) &&
- node->length <= len - offset) {
- offset += node->length;
- if ((node->type == EFI_DEV_END_PATH ||
- node->type == EFI_DEV_END_PATH2) &&
- node->sub_type == EFI_DEV_END_ENTIRE)
- return true;
- node = (struct efi_generic_dev_path *)(buffer + offset);
- }
- /*
- * If we're here then either node->length pointed past the end
- * of the buffer or we reached the end of the buffer without
- * finding a device path end node.
- */
- return false;
- }
- static bool
- validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer,
- unsigned long len)
- {
- /* An array of 16-bit integers */
- if ((len % 2) != 0)
- return false;
- return true;
- }
- static bool
- validate_load_option(efi_char16_t *var_name, int match, u8 *buffer,
- unsigned long len)
- {
- u16 filepathlength;
- int i, desclength = 0, namelen;
- namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN);
- /* Either "Boot" or "Driver" followed by four digits of hex */
- for (i = match; i < match+4; i++) {
- if (var_name[i] > 127 ||
- hex_to_bin(var_name[i] & 0xff) < 0)
- return true;
- }
- /* Reject it if there's 4 digits of hex and then further content */
- if (namelen > match + 4)
- return false;
- /* A valid entry must be at least 8 bytes */
- if (len < 8)
- return false;
- filepathlength = buffer[4] | buffer[5] << 8;
- /*
- * There's no stored length for the description, so it has to be
- * found by hand
- */
- desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
- /* Each boot entry must have a descriptor */
- if (!desclength)
- return false;
- /*
- * If the sum of the length of the description, the claimed filepath
- * length and the original header are greater than the length of the
- * variable, it's malformed
- */
- if ((desclength + filepathlength + 6) > len)
- return false;
- /*
- * And, finally, check the filepath
- */
- return validate_device_path(var_name, match, buffer + desclength + 6,
- filepathlength);
- }
- static bool
- validate_uint16(efi_char16_t *var_name, int match, u8 *buffer,
- unsigned long len)
- {
- /* A single 16-bit integer */
- if (len != 2)
- return false;
- return true;
- }
- static bool
- validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer,
- unsigned long len)
- {
- int i;
- for (i = 0; i < len; i++) {
- if (buffer[i] > 127)
- return false;
- if (buffer[i] == 0)
- return true;
- }
- return false;
- }
- struct variable_validate {
- efi_guid_t vendor;
- char *name;
- bool (*validate)(efi_char16_t *var_name, int match, u8 *data,
- unsigned long len);
- };
- /*
- * This is the list of variables we need to validate, as well as the
- * whitelist for what we think is safe not to default to immutable.
- *
- * If it has a validate() method that's not NULL, it'll go into the
- * validation routine. If not, it is assumed valid, but still used for
- * whitelisting.
- *
- * Note that it's sorted by {vendor,name}, but globbed names must come after
- * any other name with the same prefix.
- */
- static const struct variable_validate variable_validate[] = {
- { EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 },
- { EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order },
- { EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option },
- { EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order },
- { EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option },
- { EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path },
- { EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path },
- { EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path },
- { EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path },
- { EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path },
- { EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path },
- { EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string },
- { EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL },
- { EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string },
- { EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 },
- { LINUX_EFI_CRASH_GUID, "*", NULL },
- { NULL_GUID, "", NULL },
- };
- /*
- * Check if @var_name matches the pattern given in @match_name.
- *
- * @var_name: an array of @len non-NUL characters.
- * @match_name: a NUL-terminated pattern string, optionally ending in "*". A
- * final "*" character matches any trailing characters @var_name,
- * including the case when there are none left in @var_name.
- * @match: on output, the number of non-wildcard characters in @match_name
- * that @var_name matches, regardless of the return value.
- * @return: whether @var_name fully matches @match_name.
- */
- static bool
- variable_matches(const char *var_name, size_t len, const char *match_name,
- int *match)
- {
- for (*match = 0; ; (*match)++) {
- char c = match_name[*match];
- switch (c) {
- case '*':
- /* Wildcard in @match_name means we've matched. */
- return true;
- case '\0':
- /* @match_name has ended. Has @var_name too? */
- return (*match == len);
- default:
- /*
- * We've reached a non-wildcard char in @match_name.
- * Continue only if there's an identical character in
- * @var_name.
- */
- if (*match < len && c == var_name[*match])
- continue;
- return false;
- }
- }
- }
- bool
- efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
- unsigned long data_size)
- {
- int i;
- unsigned long utf8_size;
- u8 *utf8_name;
- utf8_size = ucs2_utf8size(var_name);
- utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL);
- if (!utf8_name)
- return false;
- ucs2_as_utf8(utf8_name, var_name, utf8_size);
- utf8_name[utf8_size] = '\0';
- for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
- const char *name = variable_validate[i].name;
- int match = 0;
- if (efi_guidcmp(vendor, variable_validate[i].vendor))
- continue;
- if (variable_matches(utf8_name, utf8_size+1, name, &match)) {
- if (variable_validate[i].validate == NULL)
- break;
- kfree(utf8_name);
- return variable_validate[i].validate(var_name, match,
- data, data_size);
- }
- }
- kfree(utf8_name);
- return true;
- }
- EXPORT_SYMBOL_GPL(efivar_validate);
- bool
- efivar_variable_is_removable(efi_guid_t vendor, const char *var_name,
- size_t len)
- {
- int i;
- bool found = false;
- int match = 0;
- /*
- * Check if our variable is in the validated variables list
- */
- for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
- if (efi_guidcmp(variable_validate[i].vendor, vendor))
- continue;
- if (variable_matches(var_name, len,
- variable_validate[i].name, &match)) {
- found = true;
- break;
- }
- }
- /*
- * If it's in our list, it is removable.
- */
- return found;
- }
- EXPORT_SYMBOL_GPL(efivar_variable_is_removable);
- static efi_status_t
- check_var_size(u32 attributes, unsigned long size)
- {
- const struct efivar_operations *fops;
- if (!__efivars)
- return EFI_UNSUPPORTED;
- fops = __efivars->ops;
- if (!fops->query_variable_store)
- return EFI_UNSUPPORTED;
- return fops->query_variable_store(attributes, size, false);
- }
- static efi_status_t
- check_var_size_nonblocking(u32 attributes, unsigned long size)
- {
- const struct efivar_operations *fops;
- if (!__efivars)
- return EFI_UNSUPPORTED;
- fops = __efivars->ops;
- if (!fops->query_variable_store)
- return EFI_UNSUPPORTED;
- return fops->query_variable_store(attributes, size, true);
- }
- static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor,
- struct list_head *head)
- {
- struct efivar_entry *entry, *n;
- unsigned long strsize1, strsize2;
- bool found = false;
- strsize1 = ucs2_strsize(variable_name, 1024);
- list_for_each_entry_safe(entry, n, head, list) {
- strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
- if (strsize1 == strsize2 &&
- !memcmp(variable_name, &(entry->var.VariableName),
- strsize2) &&
- !efi_guidcmp(entry->var.VendorGuid,
- *vendor)) {
- found = true;
- break;
- }
- }
- return found;
- }
- /*
- * Returns the size of variable_name, in bytes, including the
- * terminating NULL character, or variable_name_size if no NULL
- * character is found among the first variable_name_size bytes.
- */
- static unsigned long var_name_strnsize(efi_char16_t *variable_name,
- unsigned long variable_name_size)
- {
- unsigned long len;
- efi_char16_t c;
- /*
- * The variable name is, by definition, a NULL-terminated
- * string, so make absolutely sure that variable_name_size is
- * the value we expect it to be. If not, return the real size.
- */
- for (len = 2; len <= variable_name_size; len += sizeof(c)) {
- c = variable_name[(len / sizeof(c)) - 1];
- if (!c)
- break;
- }
- return min(len, variable_name_size);
- }
- /*
- * Print a warning when duplicate EFI variables are encountered and
- * disable the sysfs workqueue since the firmware is buggy.
- */
- static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
- unsigned long len16)
- {
- size_t i, len8 = len16 / sizeof(efi_char16_t);
- char *str8;
- str8 = kzalloc(len8, GFP_KERNEL);
- if (!str8)
- return;
- for (i = 0; i < len8; i++)
- str8[i] = str16[i];
- printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
- str8, vendor_guid);
- kfree(str8);
- }
- /**
- * efivar_init - build the initial list of EFI variables
- * @func: callback function to invoke for every variable
- * @data: function-specific data to pass to @func
- * @duplicates: error if we encounter duplicates on @head?
- * @head: initialised head of variable list
- *
- * Get every EFI variable from the firmware and invoke @func. @func
- * should call efivar_entry_add() to build the list of variables.
- *
- * Returns 0 on success, or a kernel error code on failure.
- */
- int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
- void *data, bool duplicates, struct list_head *head)
- {
- const struct efivar_operations *ops;
- unsigned long variable_name_size = 1024;
- efi_char16_t *variable_name;
- efi_status_t status;
- efi_guid_t vendor_guid;
- int err = 0;
- if (!__efivars)
- return -EFAULT;
- ops = __efivars->ops;
- variable_name = kzalloc(variable_name_size, GFP_KERNEL);
- if (!variable_name) {
- printk(KERN_ERR "efivars: Memory allocation failed.\n");
- return -ENOMEM;
- }
- if (down_interruptible(&efivars_lock)) {
- err = -EINTR;
- goto free;
- }
- /*
- * Per EFI spec, the maximum storage allocated for both
- * the variable name and variable data is 1024 bytes.
- */
- do {
- variable_name_size = 1024;
- status = ops->get_next_variable(&variable_name_size,
- variable_name,
- &vendor_guid);
- switch (status) {
- case EFI_SUCCESS:
- if (duplicates)
- up(&efivars_lock);
- variable_name_size = var_name_strnsize(variable_name,
- variable_name_size);
- /*
- * Some firmware implementations return the
- * same variable name on multiple calls to
- * get_next_variable(). Terminate the loop
- * immediately as there is no guarantee that
- * we'll ever see a different variable name,
- * and may end up looping here forever.
- */
- if (duplicates &&
- variable_is_present(variable_name, &vendor_guid,
- head)) {
- dup_variable_bug(variable_name, &vendor_guid,
- variable_name_size);
- status = EFI_NOT_FOUND;
- } else {
- err = func(variable_name, vendor_guid,
- variable_name_size, data);
- if (err)
- status = EFI_NOT_FOUND;
- }
- if (duplicates) {
- if (down_interruptible(&efivars_lock)) {
- err = -EINTR;
- goto free;
- }
- }
- break;
- case EFI_UNSUPPORTED:
- err = -EOPNOTSUPP;
- status = EFI_NOT_FOUND;
- break;
- case EFI_NOT_FOUND:
- break;
- default:
- printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
- status);
- status = EFI_NOT_FOUND;
- break;
- }
- } while (status != EFI_NOT_FOUND);
- up(&efivars_lock);
- free:
- kfree(variable_name);
- return err;
- }
- EXPORT_SYMBOL_GPL(efivar_init);
- /**
- * efivar_entry_add - add entry to variable list
- * @entry: entry to add to list
- * @head: list head
- *
- * Returns 0 on success, or a kernel error code on failure.
- */
- int efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
- {
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- list_add(&entry->list, head);
- up(&efivars_lock);
- return 0;
- }
- EXPORT_SYMBOL_GPL(efivar_entry_add);
- /**
- * efivar_entry_remove - remove entry from variable list
- * @entry: entry to remove from list
- *
- * Returns 0 on success, or a kernel error code on failure.
- */
- int efivar_entry_remove(struct efivar_entry *entry)
- {
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- list_del(&entry->list);
- up(&efivars_lock);
- return 0;
- }
- EXPORT_SYMBOL_GPL(efivar_entry_remove);
- /*
- * efivar_entry_list_del_unlock - remove entry from variable list
- * @entry: entry to remove
- *
- * Remove @entry from the variable list and release the list lock.
- *
- * NOTE: slightly weird locking semantics here - we expect to be
- * called with the efivars lock already held, and we release it before
- * returning. This is because this function is usually called after
- * set_variable() while the lock is still held.
- */
- static void efivar_entry_list_del_unlock(struct efivar_entry *entry)
- {
- list_del(&entry->list);
- up(&efivars_lock);
- }
- /**
- * __efivar_entry_delete - delete an EFI variable
- * @entry: entry containing EFI variable to delete
- *
- * Delete the variable from the firmware but leave @entry on the
- * variable list.
- *
- * This function differs from efivar_entry_delete() because it does
- * not remove @entry from the variable list. Also, it is safe to be
- * called from within a efivar_entry_iter_begin() and
- * efivar_entry_iter_end() region, unlike efivar_entry_delete().
- *
- * Returns 0 on success, or a converted EFI status code if
- * set_variable() fails.
- */
- int __efivar_entry_delete(struct efivar_entry *entry)
- {
- efi_status_t status;
- if (!__efivars)
- return -EINVAL;
- status = __efivars->ops->set_variable(entry->var.VariableName,
- &entry->var.VendorGuid,
- 0, 0, NULL);
- return efi_status_to_err(status);
- }
- EXPORT_SYMBOL_GPL(__efivar_entry_delete);
- /**
- * efivar_entry_delete - delete variable and remove entry from list
- * @entry: entry containing variable to delete
- *
- * Delete the variable from the firmware and remove @entry from the
- * variable list. It is the caller's responsibility to free @entry
- * once we return.
- *
- * Returns 0 on success, -EINTR if we can't grab the semaphore,
- * converted EFI status code if set_variable() fails.
- */
- int efivar_entry_delete(struct efivar_entry *entry)
- {
- const struct efivar_operations *ops;
- efi_status_t status;
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- if (!__efivars) {
- up(&efivars_lock);
- return -EINVAL;
- }
- ops = __efivars->ops;
- status = ops->set_variable(entry->var.VariableName,
- &entry->var.VendorGuid,
- 0, 0, NULL);
- if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) {
- up(&efivars_lock);
- return efi_status_to_err(status);
- }
- efivar_entry_list_del_unlock(entry);
- return 0;
- }
- EXPORT_SYMBOL_GPL(efivar_entry_delete);
- /**
- * efivar_entry_set - call set_variable()
- * @entry: entry containing the EFI variable to write
- * @attributes: variable attributes
- * @size: size of @data buffer
- * @data: buffer containing variable data
- * @head: head of variable list
- *
- * Calls set_variable() for an EFI variable. If creating a new EFI
- * variable, this function is usually followed by efivar_entry_add().
- *
- * Before writing the variable, the remaining EFI variable storage
- * space is checked to ensure there is enough room available.
- *
- * If @head is not NULL a lookup is performed to determine whether
- * the entry is already on the list.
- *
- * Returns 0 on success, -EINTR if we can't grab the semaphore,
- * -EEXIST if a lookup is performed and the entry already exists on
- * the list, or a converted EFI status code if set_variable() fails.
- */
- int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
- unsigned long size, void *data, struct list_head *head)
- {
- const struct efivar_operations *ops;
- efi_status_t status;
- efi_char16_t *name = entry->var.VariableName;
- efi_guid_t vendor = entry->var.VendorGuid;
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- if (!__efivars) {
- up(&efivars_lock);
- return -EINVAL;
- }
- ops = __efivars->ops;
- if (head && efivar_entry_find(name, vendor, head, false)) {
- up(&efivars_lock);
- return -EEXIST;
- }
- status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
- if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED)
- status = ops->set_variable(name, &vendor,
- attributes, size, data);
- up(&efivars_lock);
- return efi_status_to_err(status);
- }
- EXPORT_SYMBOL_GPL(efivar_entry_set);
- /*
- * efivar_entry_set_nonblocking - call set_variable_nonblocking()
- *
- * This function is guaranteed to not block and is suitable for calling
- * from crash/panic handlers.
- *
- * Crucially, this function will not block if it cannot acquire
- * efivars_lock. Instead, it returns -EBUSY.
- */
- static int
- efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
- u32 attributes, unsigned long size, void *data)
- {
- const struct efivar_operations *ops;
- efi_status_t status;
- if (down_trylock(&efivars_lock))
- return -EBUSY;
- if (!__efivars) {
- up(&efivars_lock);
- return -EINVAL;
- }
- status = check_var_size_nonblocking(attributes,
- size + ucs2_strsize(name, 1024));
- if (status != EFI_SUCCESS) {
- up(&efivars_lock);
- return -ENOSPC;
- }
- ops = __efivars->ops;
- status = ops->set_variable_nonblocking(name, &vendor, attributes,
- size, data);
- up(&efivars_lock);
- return efi_status_to_err(status);
- }
- /**
- * efivar_entry_set_safe - call set_variable() if enough space in firmware
- * @name: buffer containing the variable name
- * @vendor: variable vendor guid
- * @attributes: variable attributes
- * @block: can we block in this context?
- * @size: size of @data buffer
- * @data: buffer containing variable data
- *
- * Ensures there is enough free storage in the firmware for this variable, and
- * if so, calls set_variable(). If creating a new EFI variable, this function
- * is usually followed by efivar_entry_add().
- *
- * Returns 0 on success, -ENOSPC if the firmware does not have enough
- * space for set_variable() to succeed, or a converted EFI status code
- * if set_variable() fails.
- */
- int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes,
- bool block, unsigned long size, void *data)
- {
- const struct efivar_operations *ops;
- efi_status_t status;
- unsigned long varsize;
- if (!__efivars)
- return -EINVAL;
- ops = __efivars->ops;
- if (!ops->query_variable_store)
- return -ENOSYS;
- /*
- * If the EFI variable backend provides a non-blocking
- * ->set_variable() operation and we're in a context where we
- * cannot block, then we need to use it to avoid live-locks,
- * since the implication is that the regular ->set_variable()
- * will block.
- *
- * If no ->set_variable_nonblocking() is provided then
- * ->set_variable() is assumed to be non-blocking.
- */
- if (!block && ops->set_variable_nonblocking)
- return efivar_entry_set_nonblocking(name, vendor, attributes,
- size, data);
- varsize = size + ucs2_strsize(name, 1024);
- if (!block) {
- if (down_trylock(&efivars_lock))
- return -EBUSY;
- status = check_var_size_nonblocking(attributes, varsize);
- } else {
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- status = check_var_size(attributes, varsize);
- }
- if (status != EFI_SUCCESS) {
- up(&efivars_lock);
- return -ENOSPC;
- }
- status = ops->set_variable(name, &vendor, attributes, size, data);
- up(&efivars_lock);
- return efi_status_to_err(status);
- }
- EXPORT_SYMBOL_GPL(efivar_entry_set_safe);
- /**
- * efivar_entry_find - search for an entry
- * @name: the EFI variable name
- * @guid: the EFI variable vendor's guid
- * @head: head of the variable list
- * @remove: should we remove the entry from the list?
- *
- * Search for an entry on the variable list that has the EFI variable
- * name @name and vendor guid @guid. If an entry is found on the list
- * and @remove is true, the entry is removed from the list.
- *
- * The caller MUST call efivar_entry_iter_begin() and
- * efivar_entry_iter_end() before and after the invocation of this
- * function, respectively.
- *
- * Returns the entry if found on the list, %NULL otherwise.
- */
- struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid,
- struct list_head *head, bool remove)
- {
- struct efivar_entry *entry, *n;
- int strsize1, strsize2;
- bool found = false;
- list_for_each_entry_safe(entry, n, head, list) {
- strsize1 = ucs2_strsize(name, 1024);
- strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
- if (strsize1 == strsize2 &&
- !memcmp(name, &(entry->var.VariableName), strsize1) &&
- !efi_guidcmp(guid, entry->var.VendorGuid)) {
- found = true;
- break;
- }
- }
- if (!found)
- return NULL;
- if (remove) {
- if (entry->scanning) {
- /*
- * The entry will be deleted
- * after scanning is completed.
- */
- entry->deleting = true;
- } else
- list_del(&entry->list);
- }
- return entry;
- }
- EXPORT_SYMBOL_GPL(efivar_entry_find);
- /**
- * 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)
- {
- const struct efivar_operations *ops;
- efi_status_t status;
- *size = 0;
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- if (!__efivars) {
- up(&efivars_lock);
- return -EINVAL;
- }
- ops = __efivars->ops;
- status = ops->get_variable(entry->var.VariableName,
- &entry->var.VendorGuid, NULL, size, NULL);
- up(&efivars_lock);
- if (status != EFI_BUFFER_TOO_SMALL)
- return efi_status_to_err(status);
- return 0;
- }
- EXPORT_SYMBOL_GPL(efivar_entry_size);
- /**
- * __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;
- if (!__efivars)
- return -EINVAL;
- status = __efivars->ops->get_variable(entry->var.VariableName,
- &entry->var.VendorGuid,
- attributes, size, data);
- return efi_status_to_err(status);
- }
- EXPORT_SYMBOL_GPL(__efivar_entry_get);
- /**
- * 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)
- {
- efi_status_t status;
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- if (!__efivars) {
- up(&efivars_lock);
- return -EINVAL;
- }
- status = __efivars->ops->get_variable(entry->var.VariableName,
- &entry->var.VendorGuid,
- attributes, size, data);
- up(&efivars_lock);
- return efi_status_to_err(status);
- }
- EXPORT_SYMBOL_GPL(efivar_entry_get);
- /**
- * 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)
- {
- const struct efivar_operations *ops;
- 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).
- */
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- if (!__efivars) {
- err = -EINVAL;
- goto out;
- }
- /*
- * Ensure that the available space hasn't shrunk below the safe level
- */
- status = check_var_size(attributes, *size + ucs2_strsize(name, 1024));
- if (status != EFI_SUCCESS) {
- if (status != EFI_UNSUPPORTED) {
- err = efi_status_to_err(status);
- goto out;
- }
- if (*size > 65536) {
- err = -ENOSPC;
- goto out;
- }
- }
- ops = __efivars->ops;
- status = ops->set_variable(name, vendor, attributes, *size, data);
- 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 = ops->get_variable(entry->var.VariableName,
- &entry->var.VendorGuid,
- NULL, size, NULL);
- if (status == EFI_NOT_FOUND)
- efivar_entry_list_del_unlock(entry);
- else
- up(&efivars_lock);
- if (status && status != EFI_BUFFER_TOO_SMALL)
- return efi_status_to_err(status);
- return 0;
- out:
- up(&efivars_lock);
- return err;
- }
- EXPORT_SYMBOL_GPL(efivar_entry_set_get_size);
- /**
- * efivar_entry_iter_begin - begin iterating the variable list
- *
- * Lock the variable list to prevent entry insertion and removal until
- * efivar_entry_iter_end() is called. This function is usually used in
- * conjunction with __efivar_entry_iter() or efivar_entry_iter().
- */
- int efivar_entry_iter_begin(void)
- {
- return down_interruptible(&efivars_lock);
- }
- EXPORT_SYMBOL_GPL(efivar_entry_iter_begin);
- /**
- * efivar_entry_iter_end - finish iterating the variable list
- *
- * Unlock the variable list and allow modifications to the list again.
- */
- void efivar_entry_iter_end(void)
- {
- up(&efivars_lock);
- }
- EXPORT_SYMBOL_GPL(efivar_entry_iter_end);
- /**
- * __efivar_entry_iter - iterate over variable list
- * @func: callback function
- * @head: head of the variable list
- * @data: function-specific data to pass to callback
- * @prev: entry to begin iterating from
- *
- * 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().
- *
- * You MUST call efivar_entry_iter_begin() before this function, and
- * efivar_entry_iter_end() afterwards.
- *
- * It is possible to begin iteration from an arbitrary entry within
- * the list by passing @prev. @prev is updated on return to point to
- * the last entry passed to @func. To begin iterating from the
- * beginning of the list @prev must be %NULL.
- *
- * The restrictions for @func are the same as documented for
- * efivar_entry_iter().
- */
- int __efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
- struct list_head *head, void *data,
- struct efivar_entry **prev)
- {
- struct efivar_entry *entry, *n;
- int err = 0;
- if (!prev || !*prev) {
- list_for_each_entry_safe(entry, n, head, list) {
- err = func(entry, data);
- if (err)
- break;
- }
- if (prev)
- *prev = entry;
- return err;
- }
- list_for_each_entry_safe_continue((*prev), n, head, list) {
- err = func(*prev, data);
- if (err)
- break;
- }
- return err;
- }
- EXPORT_SYMBOL_GPL(__efivar_entry_iter);
- /**
- * 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)
- {
- int err = 0;
- err = efivar_entry_iter_begin();
- if (err)
- return err;
- err = __efivar_entry_iter(func, head, data, NULL);
- efivar_entry_iter_end();
- return err;
- }
- EXPORT_SYMBOL_GPL(efivar_entry_iter);
- /**
- * efivars_kobject - get the kobject for the registered efivars
- *
- * If efivars_register() has not been called we return NULL,
- * otherwise return the kobject used at registration time.
- */
- struct kobject *efivars_kobject(void)
- {
- if (!__efivars)
- return NULL;
- return __efivars->kobject;
- }
- EXPORT_SYMBOL_GPL(efivars_kobject);
- /**
- * efivars_register - register an efivars
- * @efivars: efivars to register
- * @ops: efivars operations
- * @kobject: @efivars-specific kobject
- *
- * Only a single efivars can be registered at any time.
- */
- int efivars_register(struct efivars *efivars,
- const struct efivar_operations *ops,
- struct kobject *kobject)
- {
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- efivars->ops = ops;
- efivars->kobject = kobject;
- __efivars = efivars;
- pr_info("Registered efivars operations\n");
- up(&efivars_lock);
- return 0;
- }
- EXPORT_SYMBOL_GPL(efivars_register);
- /**
- * efivars_unregister - unregister an efivars
- * @efivars: efivars to unregister
- *
- * The caller must have already removed every entry from the list,
- * failure to do so is an error.
- */
- int efivars_unregister(struct efivars *efivars)
- {
- int rv;
- if (down_interruptible(&efivars_lock))
- return -EINTR;
- if (!__efivars) {
- printk(KERN_ERR "efivars not registered\n");
- rv = -EINVAL;
- goto out;
- }
- if (__efivars != efivars) {
- rv = -EINVAL;
- goto out;
- }
- pr_info("Unregistered efivars operations\n");
- __efivars = NULL;
- rv = 0;
- out:
- up(&efivars_lock);
- return rv;
- }
- EXPORT_SYMBOL_GPL(efivars_unregister);
- int efivar_supports_writes(void)
- {
- return __efivars && __efivars->ops->set_variable;
- }
- EXPORT_SYMBOL_GPL(efivar_supports_writes);
|