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 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; 49 out: 50 return inode; 51 } 52 53 static 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 */ 70 static 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 */ 87 static 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 */ 116 static 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 */ 129 static 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 } 166 167 const 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 }; 175