cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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inode.c (4153B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (C) 2012 Red Hat, Inc.
      4 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
      5 */
      6
      7#include <linux/efi.h>
      8#include <linux/fs.h>
      9#include <linux/ctype.h>
     10#include <linux/kmemleak.h>
     11#include <linux/slab.h>
     12#include <linux/uuid.h>
     13#include <linux/fileattr.h>
     14
     15#include "internal.h"
     16
     17static const struct inode_operations efivarfs_file_inode_operations;
     18
     19struct inode *efivarfs_get_inode(struct super_block *sb,
     20				const struct inode *dir, int mode,
     21				dev_t dev, bool is_removable)
     22{
     23	struct inode *inode = new_inode(sb);
     24
     25	if (inode) {
     26		inode->i_ino = get_next_ino();
     27		inode->i_mode = mode;
     28		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
     29		inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
     30		switch (mode & S_IFMT) {
     31		case S_IFREG:
     32			inode->i_op = &efivarfs_file_inode_operations;
     33			inode->i_fop = &efivarfs_file_operations;
     34			break;
     35		case S_IFDIR:
     36			inode->i_op = &efivarfs_dir_inode_operations;
     37			inode->i_fop = &simple_dir_operations;
     38			inc_nlink(inode);
     39			break;
     40		}
     41	}
     42	return inode;
     43}
     44
     45/*
     46 * Return true if 'str' is a valid efivarfs filename of the form,
     47 *
     48 *	VariableName-12345678-1234-1234-1234-1234567891bc
     49 */
     50bool efivarfs_valid_name(const char *str, int len)
     51{
     52	const char *s = str + len - EFI_VARIABLE_GUID_LEN;
     53
     54	/*
     55	 * We need a GUID, plus at least one letter for the variable name,
     56	 * plus the '-' separator
     57	 */
     58	if (len < EFI_VARIABLE_GUID_LEN + 2)
     59		return false;
     60
     61	/* GUID must be preceded by a '-' */
     62	if (*(s - 1) != '-')
     63		return false;
     64
     65	/*
     66	 * Validate that 's' is of the correct format, e.g.
     67	 *
     68	 *	12345678-1234-1234-1234-123456789abc
     69	 */
     70	return uuid_is_valid(s);
     71}
     72
     73static int efivarfs_create(struct user_namespace *mnt_userns, struct inode *dir,
     74			   struct dentry *dentry, umode_t mode, bool excl)
     75{
     76	struct inode *inode = NULL;
     77	struct efivar_entry *var;
     78	int namelen, i = 0, err = 0;
     79	bool is_removable = false;
     80
     81	if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
     82		return -EINVAL;
     83
     84	var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
     85	if (!var)
     86		return -ENOMEM;
     87
     88	/* length of the variable name itself: remove GUID and separator */
     89	namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
     90
     91	err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid);
     92	if (err)
     93		goto out;
     94
     95	if (efivar_variable_is_removable(var->var.VendorGuid,
     96					 dentry->d_name.name, namelen))
     97		is_removable = true;
     98
     99	inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);
    100	if (!inode) {
    101		err = -ENOMEM;
    102		goto out;
    103	}
    104
    105	for (i = 0; i < namelen; i++)
    106		var->var.VariableName[i] = dentry->d_name.name[i];
    107
    108	var->var.VariableName[i] = '\0';
    109
    110	inode->i_private = var;
    111	kmemleak_ignore(var);
    112
    113	err = efivar_entry_add(var, &efivarfs_list);
    114	if (err)
    115		goto out;
    116
    117	d_instantiate(dentry, inode);
    118	dget(dentry);
    119out:
    120	if (err) {
    121		kfree(var);
    122		if (inode)
    123			iput(inode);
    124	}
    125	return err;
    126}
    127
    128static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
    129{
    130	struct efivar_entry *var = d_inode(dentry)->i_private;
    131
    132	if (efivar_entry_delete(var))
    133		return -EINVAL;
    134
    135	drop_nlink(d_inode(dentry));
    136	dput(dentry);
    137	return 0;
    138};
    139
    140const struct inode_operations efivarfs_dir_inode_operations = {
    141	.lookup = simple_lookup,
    142	.unlink = efivarfs_unlink,
    143	.create = efivarfs_create,
    144};
    145
    146static int
    147efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
    148{
    149	unsigned int i_flags;
    150	unsigned int flags = 0;
    151
    152	i_flags = d_inode(dentry)->i_flags;
    153	if (i_flags & S_IMMUTABLE)
    154		flags |= FS_IMMUTABLE_FL;
    155
    156	fileattr_fill_flags(fa, flags);
    157
    158	return 0;
    159}
    160
    161static int
    162efivarfs_fileattr_set(struct user_namespace *mnt_userns,
    163		      struct dentry *dentry, struct fileattr *fa)
    164{
    165	unsigned int i_flags = 0;
    166
    167	if (fileattr_has_fsx(fa))
    168		return -EOPNOTSUPP;
    169
    170	if (fa->flags & ~FS_IMMUTABLE_FL)
    171		return -EOPNOTSUPP;
    172
    173	if (fa->flags & FS_IMMUTABLE_FL)
    174		i_flags |= S_IMMUTABLE;
    175
    176	inode_set_flags(d_inode(dentry), i_flags, S_IMMUTABLE);
    177
    178	return 0;
    179}
    180
    181static const struct inode_operations efivarfs_file_inode_operations = {
    182	.fileattr_get = efivarfs_fileattr_get,
    183	.fileattr_set = efivarfs_fileattr_set,
    184};