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
  22 struct 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  */
  36 static 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         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;
  52 out:
  53         return inode;
  54 }
  55
  56 static 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  */
  73 static 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  */
  90 static 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  */
 119 static 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  */
 132 static 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
 170 const 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 };