super.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * eCryptfs: Linux filesystem encryption layer
  4 *
  5 * Copyright (C) 1997-2003 Erez Zadok
  6 * Copyright (C) 2001-2003 Stony Brook University
  7 * Copyright (C) 2004-2006 International Business Machines Corp.
  8 *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
  9 *              Michael C. Thompson <mcthomps@us.ibm.com>
 10 */
 11
 12#include <linux/fs.h>
 13#include <linux/mount.h>
 14#include <linux/key.h>
 15#include <linux/slab.h>
 16#include <linux/seq_file.h>
 17#include <linux/file.h>
 18#include <linux/statfs.h>
 19#include <linux/magic.h>
 20#include "ecryptfs_kernel.h"
 21
 22struct kmem_cache *ecryptfs_inode_info_cache;
 23
 24/**
 25 * ecryptfs_alloc_inode - allocate an ecryptfs inode
 26 * @sb: Pointer to the ecryptfs super block
 27 *
 28 * Called to bring an inode into existence.
 29 *
 30 * Only handle allocation, setting up structures should be done in
 31 * ecryptfs_read_inode. This is because the kernel, between now and
 32 * then, will 0 out the private data pointer.
 33 *
 34 * Returns a pointer to a newly allocated inode, NULL otherwise
 35 */
 36static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
 37{
 38	struct ecryptfs_inode_info *inode_info;
 39	struct inode *inode = NULL;
 40
 41	inode_info = alloc_inode_sb(sb, ecryptfs_inode_info_cache, GFP_KERNEL);
 42	if (unlikely(!inode_info))
 43		goto out;
 44	ecryptfs_init_crypt_stat(&inode_info->crypt_stat);
 45	mutex_init(&inode_info->lower_file_mutex);
 46	atomic_set(&inode_info->lower_file_count, 0);
 47	inode_info->lower_file = NULL;
 48	inode = &inode_info->vfs_inode;
 49out:
 50	return inode;
 51}
 52
 53static void ecryptfs_free_inode(struct inode *inode)
 54{
 55	struct ecryptfs_inode_info *inode_info;
 56	inode_info = ecryptfs_inode_to_private(inode);
 57
 58	kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
 59}
 60
 61/**
 62 * ecryptfs_destroy_inode
 63 * @inode: The ecryptfs inode
 64 *
 65 * This is used during the final destruction of the inode.  All
 66 * allocation of memory related to the inode, including allocated
 67 * memory in the crypt_stat struct, will be released here.
 68 * There should be no chance that this deallocation will be missed.
 69 */
 70static void ecryptfs_destroy_inode(struct inode *inode)
 71{
 72	struct ecryptfs_inode_info *inode_info;
 73
 74	inode_info = ecryptfs_inode_to_private(inode);
 75	BUG_ON(inode_info->lower_file);
 76	ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
 77}
 78
 79/**
 80 * ecryptfs_statfs
 81 * @dentry: The ecryptfs dentry
 82 * @buf: The struct kstatfs to fill in with stats
 83 *
 84 * Get the filesystem statistics. Currently, we let this pass right through
 85 * to the lower filesystem and take no action ourselves.
 86 */
 87static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 88{
 89	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 90	int rc;
 91
 92	if (!lower_dentry->d_sb->s_op->statfs)
 93		return -ENOSYS;
 94
 95	rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
 96	if (rc)
 97		return rc;
 98
 99	buf->f_type = ECRYPTFS_SUPER_MAGIC;
100	rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen,
101	       &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat);
102
103	return rc;
104}
105
106/**
107 * ecryptfs_evict_inode
108 * @inode: The ecryptfs inode
109 *
110 * Called by iput() when the inode reference count reached zero
111 * and the inode is not hashed anywhere.  Used to clear anything
112 * that needs to be, before the inode is completely destroyed and put
113 * on the inode free list. We use this to drop out reference to the
114 * lower inode.
115 */
116static void ecryptfs_evict_inode(struct inode *inode)
117{
118	truncate_inode_pages_final(&inode->i_data);
119	clear_inode(inode);
120	iput(ecryptfs_inode_to_lower(inode));
121}
122
123/*
124 * ecryptfs_show_options
125 *
126 * Prints the mount options for a given superblock.
127 * Returns zero; does not fail.
128 */
129static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
130{
131	struct super_block *sb = root->d_sb;
132	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
133		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
134	struct ecryptfs_global_auth_tok *walker;
135
136	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
137	list_for_each_entry(walker,
138			    &mount_crypt_stat->global_auth_tok_list,
139			    mount_crypt_stat_list) {
140		if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
141			seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
142		else
143			seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
144	}
145	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
146
147	seq_printf(m, ",ecryptfs_cipher=%s",
148		mount_crypt_stat->global_default_cipher_name);
149
150	if (mount_crypt_stat->global_default_cipher_key_size)
151		seq_printf(m, ",ecryptfs_key_bytes=%zd",
152			   mount_crypt_stat->global_default_cipher_key_size);
153	if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
154		seq_printf(m, ",ecryptfs_passthrough");
155	if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
156		seq_printf(m, ",ecryptfs_xattr_metadata");
157	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
158		seq_printf(m, ",ecryptfs_encrypted_view");
159	if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
160		seq_printf(m, ",ecryptfs_unlink_sigs");
161	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
162		seq_printf(m, ",ecryptfs_mount_auth_tok_only");
163
164	return 0;
165}
166
167const struct super_operations ecryptfs_sops = {
168	.alloc_inode = ecryptfs_alloc_inode,
169	.destroy_inode = ecryptfs_destroy_inode,
170	.free_inode = ecryptfs_free_inode,
171	.statfs = ecryptfs_statfs,
172	.evict_inode = ecryptfs_evict_inode,
173	.show_options = ecryptfs_show_options
174};