LXR linux/fs/ecryptfs/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 = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL);
  42        if (unlikely(!inode_info))
  43                goto out;
  44        if (ecryptfs_init_crypt_stat(&inode_info->crypt_stat)) {
  45                kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
  46                goto out;
  47        }
  48        mutex_init(&inode_info->lower_file_mutex);
  49        atomic_set(&inode_info->lower_file_count, 0);
  50        inode_info->lower_file = NULL;
  51        inode = &inode_info->vfs_inode;
  52out:
  53        return inode;
  54}
  55
  56static void ecryptfs_free_inode(struct inode *inode)
  57{
  58        struct ecryptfs_inode_info *inode_info;
  59        inode_info = ecryptfs_inode_to_private(inode);
  60
  61        kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
  62}
  63
  64/**
  65 * ecryptfs_destroy_inode
  66 * @inode: The ecryptfs inode
  67 *
  68 * This is used during the final destruction of the inode.  All
  69 * allocation of memory related to the inode, including allocated
  70 * memory in the crypt_stat struct, will be released here.
  71 * There should be no chance that this deallocation will be missed.
  72 */
  73static void ecryptfs_destroy_inode(struct inode *inode)
  74{
  75        struct ecryptfs_inode_info *inode_info;
  76
  77        inode_info = ecryptfs_inode_to_private(inode);
  78        BUG_ON(inode_info->lower_file);
  79        ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
  80}
  81
  82/**
  83 * ecryptfs_statfs
  84 * @dentry: The ecryptfs dentry
  85 * @buf: The struct kstatfs to fill in with stats
  86 *
  87 * Get the filesystem statistics. Currently, we let this pass right through
  88 * to the lower filesystem and take no action ourselves.
  89 */
  90static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
  91{
  92        struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
  93        int rc;
  94
  95        if (!lower_dentry->d_sb->s_op->statfs)
  96                return -ENOSYS;
  97
  98        rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
  99        if (rc)
 100                return rc;
 101
 102        buf->f_type = ECRYPTFS_SUPER_MAGIC;
 103        rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen,
 104               &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat);
 105
 106        return rc;
 107}
 108
 109/**
 110 * ecryptfs_evict_inode
 111 * @inode: The ecryptfs inode
 112 *
 113 * Called by iput() when the inode reference count reached zero
 114 * and the inode is not hashed anywhere.  Used to clear anything
 115 * that needs to be, before the inode is completely destroyed and put
 116 * on the inode free list. We use this to drop out reference to the
 117 * lower inode.
 118 */
 119static void ecryptfs_evict_inode(struct inode *inode)
 120{
 121        truncate_inode_pages_final(&inode->i_data);
 122        clear_inode(inode);
 123        iput(ecryptfs_inode_to_lower(inode));
 124}
 125
 126/*
 127 * ecryptfs_show_options
 128 *
 129 * Prints the mount options for a given superblock.
 130 * Returns zero; does not fail.
 131 */
 132static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
 133{
 134        struct super_block *sb = root->d_sb;
 135        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 136                &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
 137        struct ecryptfs_global_auth_tok *walker;
 138
 139        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 140        list_for_each_entry(walker,
 141                            &mount_crypt_stat->global_auth_tok_list,
 142                            mount_crypt_stat_list) {
 143                if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
 144                        seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
 145                else
 146                        seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
 147        }
 148        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 149
 150        seq_printf(m, ",ecryptfs_cipher=%s",
 151                mount_crypt_stat->global_default_cipher_name);
 152
 153        if (mount_crypt_stat->global_default_cipher_key_size)
 154                seq_printf(m, ",ecryptfs_key_bytes=%zd",
 155                           mount_crypt_stat->global_default_cipher_key_size);
 156        if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
 157                seq_printf(m, ",ecryptfs_passthrough");
 158        if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 159                seq_printf(m, ",ecryptfs_xattr_metadata");
 160        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 161                seq_printf(m, ",ecryptfs_encrypted_view");
 162        if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
 163                seq_printf(m, ",ecryptfs_unlink_sigs");
 164        if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 165                seq_printf(m, ",ecryptfs_mount_auth_tok_only");
 166
 167        return 0;
 168}
 169
 170const struct super_operations ecryptfs_sops = {
 171        .alloc_inode = ecryptfs_alloc_inode,
 172        .destroy_inode = ecryptfs_destroy_inode,
 173        .free_inode = ecryptfs_free_inode,
 174        .statfs = ecryptfs_statfs,
 175        .remount_fs = NULL,
 176        .evict_inode = ecryptfs_evict_inode,
 177        .show_options = ecryptfs_show_options
 178};
 179