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 = 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; 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 * @sb: The ecryptfs super block 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 }; 179