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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2012 Red Hat, Inc.4 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>5 */6 7#include <linux/ctype.h>8#include <linux/efi.h>9#include <linux/fs.h>10#include <linux/fs_context.h>11#include <linux/fs_parser.h>12#include <linux/module.h>13#include <linux/pagemap.h>14#include <linux/ucs2_string.h>15#include <linux/slab.h>16#include <linux/magic.h>17#include <linux/statfs.h>18#include <linux/notifier.h>19#include <linux/printk.h>20 21#include "internal.h"22 23static int efivarfs_ops_notifier(struct notifier_block *nb, unsigned long event,24 void *data)25{26 struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info, nb);27 28 switch (event) {29 case EFIVAR_OPS_RDONLY:30 sfi->sb->s_flags |= SB_RDONLY;31 break;32 case EFIVAR_OPS_RDWR:33 sfi->sb->s_flags &= ~SB_RDONLY;34 break;35 default:36 return NOTIFY_DONE;37 }38 39 return NOTIFY_OK;40}41 42static void efivarfs_evict_inode(struct inode *inode)43{44 clear_inode(inode);45}46 47static int efivarfs_show_options(struct seq_file *m, struct dentry *root)48{49 struct super_block *sb = root->d_sb;50 struct efivarfs_fs_info *sbi = sb->s_fs_info;51 struct efivarfs_mount_opts *opts = &sbi->mount_opts;52 53 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))54 seq_printf(m, ",uid=%u",55 from_kuid_munged(&init_user_ns, opts->uid));56 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))57 seq_printf(m, ",gid=%u",58 from_kgid_munged(&init_user_ns, opts->gid));59 return 0;60}61 62static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf)63{64 const u32 attr = EFI_VARIABLE_NON_VOLATILE |65 EFI_VARIABLE_BOOTSERVICE_ACCESS |66 EFI_VARIABLE_RUNTIME_ACCESS;67 u64 storage_space, remaining_space, max_variable_size;68 u64 id = huge_encode_dev(dentry->d_sb->s_dev);69 efi_status_t status;70 71 /* Some UEFI firmware does not implement QueryVariableInfo() */72 storage_space = remaining_space = 0;73 if (efi_rt_services_supported(EFI_RT_SUPPORTED_QUERY_VARIABLE_INFO)) {74 status = efivar_query_variable_info(attr, &storage_space,75 &remaining_space,76 &max_variable_size);77 if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED)78 pr_warn_ratelimited("query_variable_info() failed: 0x%lx\n",79 status);80 }81 82 /*83 * This is not a normal filesystem, so no point in pretending it has a block84 * size; we declare f_bsize to 1, so that we can then report the exact value85 * sent by EFI QueryVariableInfo in f_blocks and f_bfree86 */87 buf->f_bsize = 1;88 buf->f_namelen = NAME_MAX;89 buf->f_blocks = storage_space;90 buf->f_bfree = remaining_space;91 buf->f_type = dentry->d_sb->s_magic;92 buf->f_fsid = u64_to_fsid(id);93 94 /*95 * In f_bavail we declare the free space that the kernel will allow writing96 * when the storage_paranoia x86 quirk is active. To use more, users97 * should boot the kernel with efi_no_storage_paranoia.98 */99 if (remaining_space > efivar_reserved_space())100 buf->f_bavail = remaining_space - efivar_reserved_space();101 else102 buf->f_bavail = 0;103 104 return 0;105}106static const struct super_operations efivarfs_ops = {107 .statfs = efivarfs_statfs,108 .drop_inode = generic_delete_inode,109 .evict_inode = efivarfs_evict_inode,110 .show_options = efivarfs_show_options,111};112 113/*114 * Compare two efivarfs file names.115 *116 * An efivarfs filename is composed of two parts,117 *118 * 1. A case-sensitive variable name119 * 2. A case-insensitive GUID120 *121 * So we need to perform a case-sensitive match on part 1 and a122 * case-insensitive match on part 2.123 */124static int efivarfs_d_compare(const struct dentry *dentry,125 unsigned int len, const char *str,126 const struct qstr *name)127{128 int guid = len - EFI_VARIABLE_GUID_LEN;129 130 if (name->len != len)131 return 1;132 133 /* Case-sensitive compare for the variable name */134 if (memcmp(str, name->name, guid))135 return 1;136 137 /* Case-insensitive compare for the GUID */138 return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);139}140 141static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)142{143 unsigned long hash = init_name_hash(dentry);144 const unsigned char *s = qstr->name;145 unsigned int len = qstr->len;146 147 if (!efivarfs_valid_name(s, len))148 return -EINVAL;149 150 while (len-- > EFI_VARIABLE_GUID_LEN)151 hash = partial_name_hash(*s++, hash);152 153 /* GUID is case-insensitive. */154 while (len--)155 hash = partial_name_hash(tolower(*s++), hash);156 157 qstr->hash = end_name_hash(hash);158 return 0;159}160 161static const struct dentry_operations efivarfs_d_ops = {162 .d_compare = efivarfs_d_compare,163 .d_hash = efivarfs_d_hash,164 .d_delete = always_delete_dentry,165};166 167static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)168{169 struct dentry *d;170 struct qstr q;171 int err;172 173 q.name = name;174 q.len = strlen(name);175 176 err = efivarfs_d_hash(parent, &q);177 if (err)178 return ERR_PTR(err);179 180 d = d_alloc(parent, &q);181 if (d)182 return d;183 184 return ERR_PTR(-ENOMEM);185}186 187static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,188 unsigned long name_size, void *data,189 struct list_head *list)190{191 struct super_block *sb = (struct super_block *)data;192 struct efivar_entry *entry;193 struct inode *inode = NULL;194 struct dentry *dentry, *root = sb->s_root;195 unsigned long size = 0;196 char *name;197 int len;198 int err = -ENOMEM;199 bool is_removable = false;200 201 if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))202 return 0;203 204 entry = kzalloc(sizeof(*entry), GFP_KERNEL);205 if (!entry)206 return err;207 208 memcpy(entry->var.VariableName, name16, name_size);209 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));210 211 len = ucs2_utf8size(entry->var.VariableName);212 213 /* name, plus '-', plus GUID, plus NUL*/214 name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);215 if (!name)216 goto fail;217 218 ucs2_as_utf8(name, entry->var.VariableName, len);219 220 if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))221 is_removable = true;222 223 name[len] = '-';224 225 efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);226 227 name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';228 229 /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */230 strreplace(name, '/', '!');231 232 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,233 is_removable);234 if (!inode)235 goto fail_name;236 237 dentry = efivarfs_alloc_dentry(root, name);238 if (IS_ERR(dentry)) {239 err = PTR_ERR(dentry);240 goto fail_inode;241 }242 243 __efivar_entry_get(entry, NULL, &size, NULL);244 __efivar_entry_add(entry, list);245 246 /* copied by the above to local storage in the dentry. */247 kfree(name);248 249 inode_lock(inode);250 inode->i_private = entry;251 i_size_write(inode, size + sizeof(entry->var.Attributes));252 inode_unlock(inode);253 d_add(dentry, inode);254 255 return 0;256 257fail_inode:258 iput(inode);259fail_name:260 kfree(name);261fail:262 kfree(entry);263 return err;264}265 266static int efivarfs_destroy(struct efivar_entry *entry, void *data)267{268 efivar_entry_remove(entry);269 kfree(entry);270 return 0;271}272 273enum {274 Opt_uid, Opt_gid,275};276 277static const struct fs_parameter_spec efivarfs_parameters[] = {278 fsparam_uid("uid", Opt_uid),279 fsparam_gid("gid", Opt_gid),280 {},281};282 283static int efivarfs_parse_param(struct fs_context *fc, struct fs_parameter *param)284{285 struct efivarfs_fs_info *sbi = fc->s_fs_info;286 struct efivarfs_mount_opts *opts = &sbi->mount_opts;287 struct fs_parse_result result;288 int opt;289 290 opt = fs_parse(fc, efivarfs_parameters, param, &result);291 if (opt < 0)292 return opt;293 294 switch (opt) {295 case Opt_uid:296 opts->uid = result.uid;297 break;298 case Opt_gid:299 opts->gid = result.gid;300 break;301 default:302 return -EINVAL;303 }304 305 return 0;306}307 308static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)309{310 struct efivarfs_fs_info *sfi = sb->s_fs_info;311 struct inode *inode = NULL;312 struct dentry *root;313 int err;314 315 sb->s_maxbytes = MAX_LFS_FILESIZE;316 sb->s_blocksize = PAGE_SIZE;317 sb->s_blocksize_bits = PAGE_SHIFT;318 sb->s_magic = EFIVARFS_MAGIC;319 sb->s_op = &efivarfs_ops;320 sb->s_d_op = &efivarfs_d_ops;321 sb->s_time_gran = 1;322 323 if (!efivar_supports_writes())324 sb->s_flags |= SB_RDONLY;325 326 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);327 if (!inode)328 return -ENOMEM;329 inode->i_op = &efivarfs_dir_inode_operations;330 331 root = d_make_root(inode);332 sb->s_root = root;333 if (!root)334 return -ENOMEM;335 336 sfi->sb = sb;337 sfi->nb.notifier_call = efivarfs_ops_notifier;338 err = blocking_notifier_chain_register(&efivar_ops_nh, &sfi->nb);339 if (err)340 return err;341 342 return efivar_init(efivarfs_callback, sb, &sfi->efivarfs_list);343}344 345static int efivarfs_get_tree(struct fs_context *fc)346{347 return get_tree_single(fc, efivarfs_fill_super);348}349 350static int efivarfs_reconfigure(struct fs_context *fc)351{352 if (!efivar_supports_writes() && !(fc->sb_flags & SB_RDONLY)) {353 pr_err("Firmware does not support SetVariableRT. Can not remount with rw\n");354 return -EINVAL;355 }356 357 return 0;358}359 360static const struct fs_context_operations efivarfs_context_ops = {361 .get_tree = efivarfs_get_tree,362 .parse_param = efivarfs_parse_param,363 .reconfigure = efivarfs_reconfigure,364};365 366static int efivarfs_init_fs_context(struct fs_context *fc)367{368 struct efivarfs_fs_info *sfi;369 370 if (!efivar_is_available())371 return -EOPNOTSUPP;372 373 sfi = kzalloc(sizeof(*sfi), GFP_KERNEL);374 if (!sfi)375 return -ENOMEM;376 377 INIT_LIST_HEAD(&sfi->efivarfs_list);378 379 sfi->mount_opts.uid = GLOBAL_ROOT_UID;380 sfi->mount_opts.gid = GLOBAL_ROOT_GID;381 382 fc->s_fs_info = sfi;383 fc->ops = &efivarfs_context_ops;384 return 0;385}386 387static void efivarfs_kill_sb(struct super_block *sb)388{389 struct efivarfs_fs_info *sfi = sb->s_fs_info;390 391 blocking_notifier_chain_unregister(&efivar_ops_nh, &sfi->nb);392 kill_litter_super(sb);393 394 /* Remove all entries and destroy */395 efivar_entry_iter(efivarfs_destroy, &sfi->efivarfs_list, NULL);396 kfree(sfi);397}398 399static struct file_system_type efivarfs_type = {400 .owner = THIS_MODULE,401 .name = "efivarfs",402 .init_fs_context = efivarfs_init_fs_context,403 .kill_sb = efivarfs_kill_sb,404 .parameters = efivarfs_parameters,405};406 407static __init int efivarfs_init(void)408{409 return register_filesystem(&efivarfs_type);410}411 412static __exit void efivarfs_exit(void)413{414 unregister_filesystem(&efivarfs_type);415}416 417MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");418MODULE_DESCRIPTION("EFI Variable Filesystem");419MODULE_LICENSE("GPL");420MODULE_ALIAS_FS("efivarfs");421 422module_init(efivarfs_init);423module_exit(efivarfs_exit);424