xref: /linux/fs/ecryptfs/ecryptfs_kernel.h (revision 0bd2af46839ad6262d25714a6ec0365db9d6b98f)
1 /**
2  * eCryptfs: Linux filesystem encryption layer
3  * Kernel declarations.
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  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License as
12  * published by the Free Software Foundation; either version 2 of the
13  * License, or (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful, but
16  * WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
23  * 02111-1307, USA.
24  */
25 
26 #ifndef ECRYPTFS_KERNEL_H
27 #define ECRYPTFS_KERNEL_H
28 
29 #include <keys/user-type.h>
30 #include <linux/fs.h>
31 #include <linux/scatterlist.h>
32 
33 /* Version verification for shared data structures w/ userspace */
34 #define ECRYPTFS_VERSION_MAJOR 0x00
35 #define ECRYPTFS_VERSION_MINOR 0x04
36 #define ECRYPTFS_SUPPORTED_FILE_VERSION 0x01
37 /* These flags indicate which features are supported by the kernel
38  * module; userspace tools such as the mount helper read
39  * ECRYPTFS_VERSIONING_MASK from a sysfs handle in order to determine
40  * how to behave. */
41 #define ECRYPTFS_VERSIONING_PASSPHRASE 0x00000001
42 #define ECRYPTFS_VERSIONING_PUBKEY 0x00000002
43 #define ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH 0x00000004
44 #define ECRYPTFS_VERSIONING_POLICY 0x00000008
45 #define ECRYPTFS_VERSIONING_MASK (ECRYPTFS_VERSIONING_PASSPHRASE \
46                                   | ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH)
47 
48 #define ECRYPTFS_MAX_PASSWORD_LENGTH 64
49 #define ECRYPTFS_MAX_PASSPHRASE_BYTES ECRYPTFS_MAX_PASSWORD_LENGTH
50 #define ECRYPTFS_SALT_SIZE 8
51 #define ECRYPTFS_SALT_SIZE_HEX (ECRYPTFS_SALT_SIZE*2)
52 /* The original signature size is only for what is stored on disk; all
53  * in-memory representations are expanded hex, so it better adapted to
54  * be passed around or referenced on the command line */
55 #define ECRYPTFS_SIG_SIZE 8
56 #define ECRYPTFS_SIG_SIZE_HEX (ECRYPTFS_SIG_SIZE*2)
57 #define ECRYPTFS_PASSWORD_SIG_SIZE ECRYPTFS_SIG_SIZE_HEX
58 #define ECRYPTFS_MAX_KEY_BYTES 64
59 #define ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES 512
60 #define ECRYPTFS_DEFAULT_IV_BYTES 16
61 #define ECRYPTFS_FILE_VERSION 0x01
62 #define ECRYPTFS_DEFAULT_HEADER_EXTENT_SIZE 8192
63 #define ECRYPTFS_DEFAULT_EXTENT_SIZE 4096
64 #define ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE 8192
65 
66 #define RFC2440_CIPHER_DES3_EDE 0x02
67 #define RFC2440_CIPHER_CAST_5 0x03
68 #define RFC2440_CIPHER_BLOWFISH 0x04
69 #define RFC2440_CIPHER_AES_128 0x07
70 #define RFC2440_CIPHER_AES_192 0x08
71 #define RFC2440_CIPHER_AES_256 0x09
72 #define RFC2440_CIPHER_TWOFISH 0x0a
73 #define RFC2440_CIPHER_CAST_6 0x0b
74 
75 #define ECRYPTFS_SET_FLAG(flag_bit_vector, flag) (flag_bit_vector |= (flag))
76 #define ECRYPTFS_CLEAR_FLAG(flag_bit_vector, flag) (flag_bit_vector &= ~(flag))
77 #define ECRYPTFS_CHECK_FLAG(flag_bit_vector, flag) (flag_bit_vector & (flag))
78 
79 /**
80  * For convenience, we may need to pass around the encrypted session
81  * key between kernel and userspace because the authentication token
82  * may not be extractable.  For example, the TPM may not release the
83  * private key, instead requiring the encrypted data and returning the
84  * decrypted data.
85  */
86 struct ecryptfs_session_key {
87 #define ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT 0x00000001
88 #define ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT 0x00000002
89 #define ECRYPTFS_CONTAINS_DECRYPTED_KEY 0x00000004
90 #define ECRYPTFS_CONTAINS_ENCRYPTED_KEY 0x00000008
91 	u32 flags;
92 	u32 encrypted_key_size;
93 	u32 decrypted_key_size;
94 	u8 encrypted_key[ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES];
95 	u8 decrypted_key[ECRYPTFS_MAX_KEY_BYTES];
96 };
97 
98 struct ecryptfs_password {
99 	u32 password_bytes;
100 	s32 hash_algo;
101 	u32 hash_iterations;
102 	u32 session_key_encryption_key_bytes;
103 #define ECRYPTFS_PERSISTENT_PASSWORD 0x01
104 #define ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET 0x02
105 	u32 flags;
106 	/* Iterated-hash concatenation of salt and passphrase */
107 	u8 session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
108 	u8 signature[ECRYPTFS_PASSWORD_SIG_SIZE + 1];
109 	/* Always in expanded hex */
110 	u8 salt[ECRYPTFS_SALT_SIZE];
111 };
112 
113 enum ecryptfs_token_types {ECRYPTFS_PASSWORD, ECRYPTFS_PRIVATE_KEY};
114 
115 /* May be a password or a private key */
116 struct ecryptfs_auth_tok {
117 	u16 version; /* 8-bit major and 8-bit minor */
118 	u16 token_type;
119 	u32 flags;
120 	struct ecryptfs_session_key session_key;
121 	u8 reserved[32];
122 	union {
123 		struct ecryptfs_password password;
124 		/* Private key is in future eCryptfs releases */
125 	} token;
126 } __attribute__ ((packed));
127 
128 void ecryptfs_dump_auth_tok(struct ecryptfs_auth_tok *auth_tok);
129 extern void ecryptfs_to_hex(char *dst, char *src, size_t src_size);
130 extern void ecryptfs_from_hex(char *dst, char *src, int dst_size);
131 
132 struct ecryptfs_key_record {
133 	unsigned char type;
134 	size_t enc_key_size;
135 	unsigned char sig[ECRYPTFS_SIG_SIZE];
136 	unsigned char enc_key[ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES];
137 };
138 
139 struct ecryptfs_auth_tok_list {
140 	struct ecryptfs_auth_tok *auth_tok;
141 	struct list_head list;
142 };
143 
144 struct ecryptfs_crypt_stat;
145 struct ecryptfs_mount_crypt_stat;
146 
147 struct ecryptfs_page_crypt_context {
148 	struct page *page;
149 #define ECRYPTFS_PREPARE_COMMIT_MODE 0
150 #define ECRYPTFS_WRITEPAGE_MODE      1
151 	unsigned int mode;
152 	union {
153 		struct file *lower_file;
154 		struct writeback_control *wbc;
155 	} param;
156 };
157 
158 static inline struct ecryptfs_auth_tok *
159 ecryptfs_get_key_payload_data(struct key *key)
160 {
161 	return (struct ecryptfs_auth_tok *)
162 		(((struct user_key_payload*)key->payload.data)->data);
163 }
164 
165 #define ECRYPTFS_SUPER_MAGIC 0xf15f
166 #define ECRYPTFS_MAX_KEYSET_SIZE 1024
167 #define ECRYPTFS_MAX_CIPHER_NAME_SIZE 32
168 #define ECRYPTFS_MAX_NUM_ENC_KEYS 64
169 #define ECRYPTFS_MAX_NUM_KEYSIGS 2 /* TODO: Make this a linked list */
170 #define ECRYPTFS_MAX_IV_BYTES 16	/* 128 bits */
171 #define ECRYPTFS_SALT_BYTES 2
172 #define MAGIC_ECRYPTFS_MARKER 0x3c81b7f5
173 #define MAGIC_ECRYPTFS_MARKER_SIZE_BYTES 8	/* 4*2 */
174 #define ECRYPTFS_FILE_SIZE_BYTES 8
175 #define ECRYPTFS_DEFAULT_CIPHER "aes"
176 #define ECRYPTFS_DEFAULT_KEY_BYTES 16
177 #define ECRYPTFS_DEFAULT_CHAINING_MODE CRYPTO_TFM_MODE_CBC
178 #define ECRYPTFS_DEFAULT_HASH "md5"
179 #define ECRYPTFS_TAG_3_PACKET_TYPE 0x8C
180 #define ECRYPTFS_TAG_11_PACKET_TYPE 0xED
181 #define MD5_DIGEST_SIZE 16
182 
183 /**
184  * This is the primary struct associated with each encrypted file.
185  *
186  * TODO: cache align/pack?
187  */
188 struct ecryptfs_crypt_stat {
189 #define ECRYPTFS_STRUCT_INITIALIZED 0x00000001
190 #define ECRYPTFS_POLICY_APPLIED     0x00000002
191 #define ECRYPTFS_NEW_FILE           0x00000004
192 #define ECRYPTFS_ENCRYPTED          0x00000008
193 #define ECRYPTFS_SECURITY_WARNING   0x00000010
194 #define ECRYPTFS_ENABLE_HMAC        0x00000020
195 #define ECRYPTFS_ENCRYPT_IV_PAGES   0x00000040
196 #define ECRYPTFS_KEY_VALID          0x00000080
197 	u32 flags;
198 	unsigned int file_version;
199 	size_t iv_bytes;
200 	size_t num_keysigs;
201 	size_t header_extent_size;
202 	size_t num_header_extents_at_front;
203 	size_t extent_size; /* Data extent size; default is 4096 */
204 	size_t key_size;
205 	size_t extent_shift;
206 	unsigned int extent_mask;
207 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
208 	struct crypto_blkcipher *tfm;
209 	struct crypto_hash *hash_tfm; /* Crypto context for generating
210 				       * the initialization vectors */
211 	unsigned char cipher[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
212 	unsigned char key[ECRYPTFS_MAX_KEY_BYTES];
213 	unsigned char root_iv[ECRYPTFS_MAX_IV_BYTES];
214 	unsigned char keysigs[ECRYPTFS_MAX_NUM_KEYSIGS][ECRYPTFS_SIG_SIZE_HEX];
215 	struct mutex cs_tfm_mutex;
216 	struct mutex cs_hash_tfm_mutex;
217 	struct mutex cs_mutex;
218 };
219 
220 /* inode private data. */
221 struct ecryptfs_inode_info {
222 	struct inode vfs_inode;
223 	struct inode *wii_inode;
224 	struct ecryptfs_crypt_stat crypt_stat;
225 };
226 
227 /* dentry private data. Each dentry must keep track of a lower
228  * vfsmount too. */
229 struct ecryptfs_dentry_info {
230 	struct dentry *wdi_dentry;
231 	struct vfsmount *lower_mnt;
232 	struct ecryptfs_crypt_stat *crypt_stat;
233 };
234 
235 /**
236  * This struct is to enable a mount-wide passphrase/salt combo. This
237  * is more or less a stopgap to provide similar functionality to other
238  * crypto filesystems like EncFS or CFS until full policy support is
239  * implemented in eCryptfs.
240  */
241 struct ecryptfs_mount_crypt_stat {
242 	/* Pointers to memory we do not own, do not free these */
243 #define ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED 0x00000001
244 	u32 flags;
245 	struct ecryptfs_auth_tok *global_auth_tok;
246 	struct key *global_auth_tok_key;
247 	size_t global_default_cipher_key_size;
248 	struct crypto_blkcipher *global_key_tfm;
249 	struct mutex global_key_tfm_mutex;
250 	unsigned char global_default_cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE
251 						 + 1];
252 	unsigned char global_auth_tok_sig[ECRYPTFS_SIG_SIZE_HEX + 1];
253 };
254 
255 /* superblock private data. */
256 struct ecryptfs_sb_info {
257 	struct super_block *wsi_sb;
258 	struct ecryptfs_mount_crypt_stat mount_crypt_stat;
259 };
260 
261 /* file private data. */
262 struct ecryptfs_file_info {
263 	struct file *wfi_file;
264 	struct ecryptfs_crypt_stat *crypt_stat;
265 };
266 
267 /* auth_tok <=> encrypted_session_key mappings */
268 struct ecryptfs_auth_tok_list_item {
269 	unsigned char encrypted_session_key[ECRYPTFS_MAX_KEY_BYTES];
270 	struct list_head list;
271 	struct ecryptfs_auth_tok auth_tok;
272 };
273 
274 static inline struct ecryptfs_file_info *
275 ecryptfs_file_to_private(struct file *file)
276 {
277 	return (struct ecryptfs_file_info *)file->private_data;
278 }
279 
280 static inline void
281 ecryptfs_set_file_private(struct file *file,
282 			  struct ecryptfs_file_info *file_info)
283 {
284 	file->private_data = file_info;
285 }
286 
287 static inline struct file *ecryptfs_file_to_lower(struct file *file)
288 {
289 	return ((struct ecryptfs_file_info *)file->private_data)->wfi_file;
290 }
291 
292 static inline void
293 ecryptfs_set_file_lower(struct file *file, struct file *lower_file)
294 {
295 	((struct ecryptfs_file_info *)file->private_data)->wfi_file =
296 		lower_file;
297 }
298 
299 static inline struct ecryptfs_inode_info *
300 ecryptfs_inode_to_private(struct inode *inode)
301 {
302 	return container_of(inode, struct ecryptfs_inode_info, vfs_inode);
303 }
304 
305 static inline struct inode *ecryptfs_inode_to_lower(struct inode *inode)
306 {
307 	return ecryptfs_inode_to_private(inode)->wii_inode;
308 }
309 
310 static inline void
311 ecryptfs_set_inode_lower(struct inode *inode, struct inode *lower_inode)
312 {
313 	ecryptfs_inode_to_private(inode)->wii_inode = lower_inode;
314 }
315 
316 static inline struct ecryptfs_sb_info *
317 ecryptfs_superblock_to_private(struct super_block *sb)
318 {
319 	return (struct ecryptfs_sb_info *)sb->s_fs_info;
320 }
321 
322 static inline void
323 ecryptfs_set_superblock_private(struct super_block *sb,
324 				struct ecryptfs_sb_info *sb_info)
325 {
326 	sb->s_fs_info = sb_info;
327 }
328 
329 static inline struct super_block *
330 ecryptfs_superblock_to_lower(struct super_block *sb)
331 {
332 	return ((struct ecryptfs_sb_info *)sb->s_fs_info)->wsi_sb;
333 }
334 
335 static inline void
336 ecryptfs_set_superblock_lower(struct super_block *sb,
337 			      struct super_block *lower_sb)
338 {
339 	((struct ecryptfs_sb_info *)sb->s_fs_info)->wsi_sb = lower_sb;
340 }
341 
342 static inline struct ecryptfs_dentry_info *
343 ecryptfs_dentry_to_private(struct dentry *dentry)
344 {
345 	return (struct ecryptfs_dentry_info *)dentry->d_fsdata;
346 }
347 
348 static inline void
349 ecryptfs_set_dentry_private(struct dentry *dentry,
350 			    struct ecryptfs_dentry_info *dentry_info)
351 {
352 	dentry->d_fsdata = dentry_info;
353 }
354 
355 static inline struct dentry *
356 ecryptfs_dentry_to_lower(struct dentry *dentry)
357 {
358 	return ((struct ecryptfs_dentry_info *)dentry->d_fsdata)->wdi_dentry;
359 }
360 
361 static inline void
362 ecryptfs_set_dentry_lower(struct dentry *dentry, struct dentry *lower_dentry)
363 {
364 	((struct ecryptfs_dentry_info *)dentry->d_fsdata)->wdi_dentry =
365 		lower_dentry;
366 }
367 
368 static inline struct vfsmount *
369 ecryptfs_dentry_to_lower_mnt(struct dentry *dentry)
370 {
371 	return ((struct ecryptfs_dentry_info *)dentry->d_fsdata)->lower_mnt;
372 }
373 
374 static inline void
375 ecryptfs_set_dentry_lower_mnt(struct dentry *dentry, struct vfsmount *lower_mnt)
376 {
377 	((struct ecryptfs_dentry_info *)dentry->d_fsdata)->lower_mnt =
378 		lower_mnt;
379 }
380 
381 #define ecryptfs_printk(type, fmt, arg...) \
382         __ecryptfs_printk(type "%s: " fmt, __FUNCTION__, ## arg);
383 void __ecryptfs_printk(const char *fmt, ...);
384 
385 extern const struct file_operations ecryptfs_main_fops;
386 extern const struct file_operations ecryptfs_dir_fops;
387 extern struct inode_operations ecryptfs_main_iops;
388 extern struct inode_operations ecryptfs_dir_iops;
389 extern struct inode_operations ecryptfs_symlink_iops;
390 extern struct super_operations ecryptfs_sops;
391 extern struct dentry_operations ecryptfs_dops;
392 extern struct address_space_operations ecryptfs_aops;
393 extern int ecryptfs_verbosity;
394 
395 extern struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
396 extern struct kmem_cache *ecryptfs_file_info_cache;
397 extern struct kmem_cache *ecryptfs_dentry_info_cache;
398 extern struct kmem_cache *ecryptfs_inode_info_cache;
399 extern struct kmem_cache *ecryptfs_sb_info_cache;
400 extern struct kmem_cache *ecryptfs_header_cache_0;
401 extern struct kmem_cache *ecryptfs_header_cache_1;
402 extern struct kmem_cache *ecryptfs_header_cache_2;
403 extern struct kmem_cache *ecryptfs_lower_page_cache;
404 
405 int ecryptfs_interpose(struct dentry *hidden_dentry,
406 		       struct dentry *this_dentry, struct super_block *sb,
407 		       int flag);
408 int ecryptfs_fill_zeros(struct file *file, loff_t new_length);
409 int ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
410 			     const char *name, int length,
411 			     char **decrypted_name);
412 int ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
413 			     const char *name, int length,
414 			     char **encoded_name);
415 struct dentry *ecryptfs_lower_dentry(struct dentry *this_dentry);
416 void ecryptfs_copy_attr_atime(struct inode *dest, const struct inode *src);
417 void ecryptfs_copy_attr_all(struct inode *dest, const struct inode *src);
418 void ecryptfs_copy_inode_size(struct inode *dst, const struct inode *src);
419 void ecryptfs_dump_hex(char *data, int bytes);
420 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
421 			int sg_size);
422 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat);
423 void ecryptfs_rotate_iv(unsigned char *iv);
424 void ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat);
425 void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat);
426 void ecryptfs_destruct_mount_crypt_stat(
427 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat);
428 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat);
429 int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
430 					   char *cipher_name,
431 					   char *chaining_modifier);
432 int ecryptfs_write_inode_size_to_header(struct file *lower_file,
433 					struct inode *lower_inode,
434 					struct inode *inode);
435 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
436 			    struct file *lower_file,
437 			    unsigned long lower_page_index, int byte_offset,
438 			    int region_bytes);
439 int
440 ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
441 			   struct file *lower_file, int byte_offset,
442 			   int region_size);
443 int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
444 				struct file *lower_file);
445 int ecryptfs_do_readpage(struct file *file, struct page *page,
446 			 pgoff_t lower_page_index);
447 int ecryptfs_grab_and_map_lower_page(struct page **lower_page,
448 				     char **lower_virt,
449 				     struct inode *lower_inode,
450 				     unsigned long lower_page_index);
451 int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
452 					      struct inode *lower_inode,
453 					      struct writeback_control *wbc);
454 int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx);
455 int ecryptfs_decrypt_page(struct file *file, struct page *page);
456 int ecryptfs_write_headers(struct dentry *ecryptfs_dentry,
457 			   struct file *lower_file);
458 int ecryptfs_write_headers_virt(char *page_virt,
459 				struct ecryptfs_crypt_stat *crypt_stat,
460 				struct dentry *ecryptfs_dentry);
461 int ecryptfs_read_headers(struct dentry *ecryptfs_dentry,
462 			  struct file *lower_file);
463 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry);
464 int contains_ecryptfs_marker(char *data);
465 int ecryptfs_read_header_region(char *data, struct dentry *dentry,
466 				struct vfsmount *mnt);
467 u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat);
468 int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code);
469 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat);
470 int ecryptfs_generate_key_packet_set(char *dest_base,
471 				     struct ecryptfs_crypt_stat *crypt_stat,
472 				     struct dentry *ecryptfs_dentry,
473 				     size_t *len, size_t max);
474 int process_request_key_err(long err_code);
475 int
476 ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
477 			  unsigned char *src, struct dentry *ecryptfs_dentry);
478 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length);
479 int
480 ecryptfs_process_cipher(struct crypto_blkcipher **key_tfm, char *cipher_name,
481 			size_t *key_size);
482 int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode);
483 int ecryptfs_inode_set(struct inode *inode, void *lower_inode);
484 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode);
485 int ecryptfs_open_lower_file(struct file **lower_file,
486 			     struct dentry *lower_dentry,
487 			     struct vfsmount *lower_mnt, int flags);
488 int ecryptfs_close_lower_file(struct file *lower_file);
489 
490 #endif /* #ifndef ECRYPTFS_KERNEL_H */
491