// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2012 Red Hat, Inc.
* Copyright (C) 2012 Jeremy Kerr <[email protected]>
*/
#include <linux/ctype.h>
#include <linux/efi.h>
#include <linux/fs.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/ucs2_string.h>
#include <linux/slab.h>
#include <linux/magic.h>
#include <linux/statfs.h>
#include <linux/notifier.h>
#include <linux/printk.h>
#include "internal.h"
static int efivarfs_ops_notifier(struct notifier_block *nb, unsigned long event,
void *data)
{
struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info, nb);
switch (event) {
case EFIVAR_OPS_RDONLY:
sfi->sb->s_flags |= SB_RDONLY;
break;
case EFIVAR_OPS_RDWR:
sfi->sb->s_flags &= ~SB_RDONLY;
break;
default:
return NOTIFY_DONE;
}
return NOTIFY_OK;
}
static void efivarfs_evict_inode(struct inode *inode)
{
clear_inode(inode);
}
static int efivarfs_show_options(struct seq_file *m, struct dentry *root)
{
struct super_block *sb = root->d_sb;
struct efivarfs_fs_info *sbi = sb->s_fs_info;
struct efivarfs_mount_opts *opts = &sbi->mount_opts;
if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
seq_printf(m, ",uid=%u",
from_kuid_munged(&init_user_ns, opts->uid));
if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
seq_printf(m, ",gid=%u",
from_kgid_munged(&init_user_ns, opts->gid));
return 0;
}
static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
const u32 attr = EFI_VARIABLE_NON_VOLATILE |
EFI_VARIABLE_BOOTSERVICE_ACCESS |
EFI_VARIABLE_RUNTIME_ACCESS;
u64 storage_space, remaining_space, max_variable_size;
u64 id = huge_encode_dev(dentry->d_sb->s_dev);
efi_status_t status;
/* Some UEFI firmware does not implement QueryVariableInfo() */
storage_space = remaining_space = 0;
if (efi_rt_services_supported(EFI_RT_SUPPORTED_QUERY_VARIABLE_INFO)) {
status = efivar_query_variable_info(attr, &storage_space,
&remaining_space,
&max_variable_size);
if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED)
pr_warn_ratelimited("query_variable_info() failed: 0x%lx\n",
status);
}
/*
* This is not a normal filesystem, so no point in pretending it has a block
* size; we declare f_bsize to 1, so that we can then report the exact value
* sent by EFI QueryVariableInfo in f_blocks and f_bfree
*/
buf->f_bsize = 1;
buf->f_namelen = NAME_MAX;
buf->f_blocks = storage_space;
buf->f_bfree = remaining_space;
buf->f_type = dentry->d_sb->s_magic;
buf->f_fsid = u64_to_fsid(id);
/*
* In f_bavail we declare the free space that the kernel will allow writing
* when the storage_paranoia x86 quirk is active. To use more, users
* should boot the kernel with efi_no_storage_paranoia.
*/
if (remaining_space > efivar_reserved_space())
buf->f_bavail = remaining_space - efivar_reserved_space();
else
buf->f_bavail = 0;
return 0;
}
static const struct super_operations efivarfs_ops = {
.statfs = efivarfs_statfs,
.drop_inode = generic_delete_inode,
.evict_inode = efivarfs_evict_inode,
.show_options = efivarfs_show_options,
};
/*
* Compare two efivarfs file names.
*
* An efivarfs filename is composed of two parts,
*
* 1. A case-sensitive variable name
* 2. A case-insensitive GUID
*
* So we need to perform a case-sensitive match on part 1 and a
* case-insensitive match on part 2.
*/
static int efivarfs_d_compare(const struct dentry *dentry,
unsigned int len, const char *str,
const struct qstr *name)
{
int guid = len - EFI_VARIABLE_GUID_LEN;
if (name->len != len)
return 1;
/* Case-sensitive compare for the variable name */
if (memcmp(str, name->name, guid))
return 1;
/* Case-insensitive compare for the GUID */
return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
}
static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
{
unsigned long hash = init_name_hash(dentry);
const unsigned char *s = qstr->name;
unsigned int len = qstr->len;
if (!efivarfs_valid_name(s, len))
return -EINVAL;
while (len-- > EFI_VARIABLE_GUID_LEN)
hash = partial_name_hash(*s++, hash);
/* GUID is case-insensitive. */
while (len--)
hash = partial_name_hash(tolower(*s++), hash);
qstr->hash = end_name_hash(hash);
return 0;
}
static const struct dentry_operations efivarfs_d_ops = {
.d_compare = efivarfs_d_compare,
.d_hash = efivarfs_d_hash,
.d_delete = always_delete_dentry,
};
static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
{
struct dentry *d;
struct qstr q;
int err;
q.name = name;
q.len = strlen(name);
err = efivarfs_d_hash(parent, &q);
if (err)
return ERR_PTR(err);
d = d_alloc(parent, &q);
if (d)
return d;
return ERR_PTR(-ENOMEM);
}
static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
unsigned long name_size, void *data,
struct list_head *list)
{
struct super_block *sb = (struct super_block *)data;
struct efivar_entry *entry;
struct inode *inode = NULL;
struct dentry *dentry, *root = sb->s_root;
unsigned long size = 0;
char *name;
int len;
int err = -ENOMEM;
bool is_removable = false;
if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
return 0;
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
return err;
memcpy(entry->var.VariableName, name16, name_size);
memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
len = ucs2_utf8size(entry->var.VariableName);
/* name, plus '-', plus GUID, plus NUL*/
name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
if (!name)
goto fail;
ucs2_as_utf8(name, entry->var.VariableName, len);
if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
is_removable = true;
name[len] = '-';
efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
/* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
strreplace(name, '/', '!');
inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
is_removable);
if (!inode)
goto fail_name;
dentry = efivarfs_alloc_dentry(root, name);
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
goto fail_inode;
}
__efivar_entry_get(entry, NULL, &size, NULL);
__efivar_entry_add(entry, list);
/* copied by the above to local storage in the dentry. */
kfree(name);
inode_lock(inode);
inode->i_private = entry;
i_size_write(inode, size + sizeof(entry->var.Attributes));
inode_unlock(inode);
d_add(dentry, inode);
return 0;
fail_inode:
iput(inode);
fail_name:
kfree(name);
fail:
kfree(entry);
return err;
}
static int efivarfs_destroy(struct efivar_entry *entry, void *data)
{
efivar_entry_remove(entry);
kfree(entry);
return 0;
}
enum {
Opt_uid, Opt_gid,
};
static const struct fs_parameter_spec efivarfs_parameters[] = {
fsparam_uid("uid", Opt_uid),
fsparam_gid("gid", Opt_gid),
{},
};
static int efivarfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
struct efivarfs_fs_info *sbi = fc->s_fs_info;
struct efivarfs_mount_opts *opts = &sbi->mount_opts;
struct fs_parse_result result;
int opt;
opt = fs_parse(fc, efivarfs_parameters, param, &result);
if (opt < 0)
return opt;
switch (opt) {
case Opt_uid:
opts->uid = result.uid;
break;
case Opt_gid:
opts->gid = result.gid;
break;
default:
return -EINVAL;
}
return 0;
}
static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
struct efivarfs_fs_info *sfi = sb->s_fs_info;
struct inode *inode = NULL;
struct dentry *root;
int err;
sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_blocksize = PAGE_SIZE;
sb->s_blocksize_bits = PAGE_SHIFT;
sb->s_magic = EFIVARFS_MAGIC;
sb->s_op = &efivarfs_ops;
sb->s_d_op = &efivarfs_d_ops;
sb->s_time_gran = 1;
if (!efivar_supports_writes())
sb->s_flags |= SB_RDONLY;
inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
if (!inode)
return -ENOMEM;
inode->i_op = &efivarfs_dir_inode_operations;
root = d_make_root(inode);
sb->s_root = root;
if (!root)
return -ENOMEM;
sfi->sb = sb;
sfi->nb.notifier_call = efivarfs_ops_notifier;
err = blocking_notifier_chain_register(&efivar_ops_nh, &sfi->nb);
if (err)
return err;
return efivar_init(efivarfs_callback, sb, &sfi->efivarfs_list);
}
static int efivarfs_get_tree(struct fs_context *fc)
{
return get_tree_single(fc, efivarfs_fill_super);
}
static int efivarfs_reconfigure(struct fs_context *fc)
{
if (!efivar_supports_writes() && !(fc->sb_flags & SB_RDONLY)) {
pr_err("Firmware does not support SetVariableRT. Can not remount with rw\n");
return -EINVAL;
}
return 0;
}
static const struct fs_context_operations efivarfs_context_ops = {
.get_tree = efivarfs_get_tree,
.parse_param = efivarfs_parse_param,
.reconfigure = efivarfs_reconfigure,
};
static int efivarfs_init_fs_context(struct fs_context *fc)
{
struct efivarfs_fs_info *sfi;
if (!efivar_is_available())
return -EOPNOTSUPP;
sfi = kzalloc(sizeof(*sfi), GFP_KERNEL);
if (!sfi)
return -ENOMEM;
INIT_LIST_HEAD(&sfi->efivarfs_list);
sfi->mount_opts.uid = GLOBAL_ROOT_UID;
sfi->mount_opts.gid = GLOBAL_ROOT_GID;
fc->s_fs_info = sfi;
fc->ops = &efivarfs_context_ops;
return 0;
}
static void efivarfs_kill_sb(struct super_block *sb)
{
struct efivarfs_fs_info *sfi = sb->s_fs_info;
blocking_notifier_chain_unregister(&efivar_ops_nh, &sfi->nb);
kill_litter_super(sb);
/* Remove all entries and destroy */
efivar_entry_iter(efivarfs_destroy, &sfi->efivarfs_list, NULL);
kfree(sfi);
}
static struct file_system_type efivarfs_type = {
.owner = THIS_MODULE,
.name = "efivarfs",
.init_fs_context = efivarfs_init_fs_context,
.kill_sb = efivarfs_kill_sb,
.parameters = efivarfs_parameters,
};
static __init int efivarfs_init(void)
{
return register_filesystem(&efivarfs_type);
}
static __exit void efivarfs_exit(void)
{
unregister_filesystem(&efivarfs_type);
}
MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
MODULE_DESCRIPTION("EFI Variable Filesystem");
MODULE_LICENSE("GPL");
MODULE_ALIAS_FS("efivarfs");
module_init(efivarfs_init);
module_exit(efivarfs_exit);
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