diff options
Diffstat (limited to 'fs/efivarfs/inode.c')
| -rw-r--r-- | fs/efivarfs/inode.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c new file mode 100644 index 0000000000..db9231f0e7 --- /dev/null +++ b/fs/efivarfs/inode.c @@ -0,0 +1,188 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2012 Red Hat, Inc. + * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> + */ + +#include <linux/efi.h> +#include <linux/fs.h> +#include <linux/ctype.h> +#include <linux/kmemleak.h> +#include <linux/slab.h> +#include <linux/uuid.h> +#include <linux/fileattr.h> + +#include "internal.h" + +static const struct inode_operations efivarfs_file_inode_operations; + +struct inode *efivarfs_get_inode(struct super_block *sb, + const struct inode *dir, int mode, + dev_t dev, bool is_removable) +{ + struct inode *inode = new_inode(sb); + + if (inode) { + inode->i_ino = get_next_ino(); + inode->i_mode = mode; + inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode); + inode->i_flags = is_removable ? 0 : S_IMMUTABLE; + switch (mode & S_IFMT) { + case S_IFREG: + inode->i_op = &efivarfs_file_inode_operations; + inode->i_fop = &efivarfs_file_operations; + break; + case S_IFDIR: + inode->i_op = &efivarfs_dir_inode_operations; + inode->i_fop = &simple_dir_operations; + inc_nlink(inode); + break; + } + } + return inode; +} + +/* + * Return true if 'str' is a valid efivarfs filename of the form, + * + * VariableName-12345678-1234-1234-1234-1234567891bc + */ +bool efivarfs_valid_name(const char *str, int len) +{ + const char *s = str + len - EFI_VARIABLE_GUID_LEN; + + /* + * We need a GUID, plus at least one letter for the variable name, + * plus the '-' separator + */ + if (len < EFI_VARIABLE_GUID_LEN + 2) + return false; + + /* GUID must be preceded by a '-' */ + if (*(s - 1) != '-') + return false; + + /* + * Validate that 's' is of the correct format, e.g. + * + * 12345678-1234-1234-1234-123456789abc + */ + return uuid_is_valid(s); +} + +static int efivarfs_create(struct mnt_idmap *idmap, struct inode *dir, + struct dentry *dentry, umode_t mode, bool excl) +{ + struct inode *inode = NULL; + struct efivar_entry *var; + int namelen, i = 0, err = 0; + bool is_removable = false; + + if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) + return -EINVAL; + + var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); + if (!var) + return -ENOMEM; + + /* length of the variable name itself: remove GUID and separator */ + namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1; + + err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid); + if (err) + goto out; + if (guid_equal(&var->var.VendorGuid, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) { + err = -EPERM; + goto out; + } + + if (efivar_variable_is_removable(var->var.VendorGuid, + dentry->d_name.name, namelen)) + is_removable = true; + + inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable); + if (!inode) { + err = -ENOMEM; + goto out; + } + + for (i = 0; i < namelen; i++) + var->var.VariableName[i] = dentry->d_name.name[i]; + + var->var.VariableName[i] = '\0'; + + inode->i_private = var; + kmemleak_ignore(var); + + err = efivar_entry_add(var, &efivarfs_list); + if (err) + goto out; + + d_instantiate(dentry, inode); + dget(dentry); +out: + if (err) { + kfree(var); + if (inode) + iput(inode); + } + return err; +} + +static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) +{ + struct efivar_entry *var = d_inode(dentry)->i_private; + + if (efivar_entry_delete(var)) + return -EINVAL; + + drop_nlink(d_inode(dentry)); + dput(dentry); + return 0; +}; + +const struct inode_operations efivarfs_dir_inode_operations = { + .lookup = simple_lookup, + .unlink = efivarfs_unlink, + .create = efivarfs_create, +}; + +static int +efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa) +{ + unsigned int i_flags; + unsigned int flags = 0; + + i_flags = d_inode(dentry)->i_flags; + if (i_flags & S_IMMUTABLE) + flags |= FS_IMMUTABLE_FL; + + fileattr_fill_flags(fa, flags); + + return 0; +} + +static int +efivarfs_fileattr_set(struct mnt_idmap *idmap, + struct dentry *dentry, struct fileattr *fa) +{ + unsigned int i_flags = 0; + + if (fileattr_has_fsx(fa)) + return -EOPNOTSUPP; + + if (fa->flags & ~FS_IMMUTABLE_FL) + return -EOPNOTSUPP; + + if (fa->flags & FS_IMMUTABLE_FL) + i_flags |= S_IMMUTABLE; + + inode_set_flags(d_inode(dentry), i_flags, S_IMMUTABLE); + + return 0; +} + +static const struct inode_operations efivarfs_file_inode_operations = { + .fileattr_get = efivarfs_fileattr_get, + .fileattr_set = efivarfs_fileattr_set, +}; |