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1/*
2 * General per-file encryption definition
3 *
4 * Copyright (C) 2015, Google, Inc.
5 *
6 * Written by Michael Halcrow, 2015.
7 * Modified by Jaegeuk Kim, 2015.
8 */
9
10#ifndef _LINUX_FSCRYPTO_H
11#define _LINUX_FSCRYPTO_H
12
13#include <linux/key.h>
14#include <linux/fs.h>
15#include <linux/mm.h>
16#include <linux/bio.h>
17#include <linux/dcache.h>
18#include <crypto/skcipher.h>
19#include <uapi/linux/fs.h>
20
21#define FS_CRYPTO_BLOCK_SIZE 16
22
23struct fscrypt_info;
24
25struct fscrypt_ctx {
26 union {
27 struct {
28 struct page *bounce_page; /* Ciphertext page */
29 struct page *control_page; /* Original page */
30 } w;
31 struct {
32 struct bio *bio;
33 struct work_struct work;
34 } r;
35 struct list_head free_list; /* Free list */
36 };
37 u8 flags; /* Flags */
38 u8 mode; /* Encryption mode for tfm */
39};
40
41/**
42 * For encrypted symlinks, the ciphertext length is stored at the beginning
43 * of the string in little-endian format.
44 */
45struct fscrypt_symlink_data {
46 __le16 len;
47 char encrypted_path[1];
48} __packed;
49
50/**
51 * This function is used to calculate the disk space required to
52 * store a filename of length l in encrypted symlink format.
53 */
54static inline u32 fscrypt_symlink_data_len(u32 l)
55{
56 if (l < FS_CRYPTO_BLOCK_SIZE)
57 l = FS_CRYPTO_BLOCK_SIZE;
58 return (l + sizeof(struct fscrypt_symlink_data) - 1);
59}
60
61struct fscrypt_str {
62 unsigned char *name;
63 u32 len;
64};
65
66struct fscrypt_name {
67 const struct qstr *usr_fname;
68 struct fscrypt_str disk_name;
69 u32 hash;
70 u32 minor_hash;
71 struct fscrypt_str crypto_buf;
72};
73
74#define FSTR_INIT(n, l) { .name = n, .len = l }
75#define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
76#define fname_name(p) ((p)->disk_name.name)
77#define fname_len(p) ((p)->disk_name.len)
78
79/*
80 * fscrypt superblock flags
81 */
82#define FS_CFLG_OWN_PAGES (1U << 1)
83
84/*
85 * crypto opertions for filesystems
86 */
87struct fscrypt_operations {
88 unsigned int flags;
89 int (*get_context)(struct inode *, void *, size_t);
90 int (*key_prefix)(struct inode *, u8 **);
91 int (*prepare_context)(struct inode *);
92 int (*set_context)(struct inode *, const void *, size_t, void *);
93 int (*dummy_context)(struct inode *);
94 bool (*is_encrypted)(struct inode *);
95 bool (*empty_dir)(struct inode *);
96 unsigned (*max_namelen)(struct inode *);
97};
98
99static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
100{
101 if (inode->i_sb->s_cop->dummy_context &&
102 inode->i_sb->s_cop->dummy_context(inode))
103 return true;
104 return false;
105}
106
107static inline bool fscrypt_valid_contents_enc_mode(u32 mode)
108{
109 return (mode == FS_ENCRYPTION_MODE_AES_256_XTS);
110}
111
112static inline bool fscrypt_valid_filenames_enc_mode(u32 mode)
113{
114 return (mode == FS_ENCRYPTION_MODE_AES_256_CTS);
115}
116
117static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
118{
119 if (str->len == 1 && str->name[0] == '.')
120 return true;
121
122 if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
123 return true;
124
125 return false;
126}
127
128static inline struct page *fscrypt_control_page(struct page *page)
129{
130#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
131 return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
132#else
133 WARN_ON_ONCE(1);
134 return ERR_PTR(-EINVAL);
135#endif
136}
137
138static inline int fscrypt_has_encryption_key(const struct inode *inode)
139{
140#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
141 return (inode->i_crypt_info != NULL);
142#else
143 return 0;
144#endif
145}
146
147static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry)
148{
149#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
150 spin_lock(&dentry->d_lock);
151 dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
152 spin_unlock(&dentry->d_lock);
153#endif
154}
155
156#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
157extern const struct dentry_operations fscrypt_d_ops;
158#endif
159
160static inline void fscrypt_set_d_op(struct dentry *dentry)
161{
162#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
163 d_set_d_op(dentry, &fscrypt_d_ops);
164#endif
165}
166
167#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
168/* crypto.c */
169extern struct kmem_cache *fscrypt_info_cachep;
170extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
171extern void fscrypt_release_ctx(struct fscrypt_ctx *);
172extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
173 unsigned int, unsigned int,
174 u64, gfp_t);
175extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
176 unsigned int, u64);
177extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
178extern void fscrypt_pullback_bio_page(struct page **, bool);
179extern void fscrypt_restore_control_page(struct page *);
180extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
181 unsigned int);
182/* policy.c */
183extern int fscrypt_ioctl_set_policy(struct file *, const void __user *);
184extern int fscrypt_ioctl_get_policy(struct file *, void __user *);
185extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
186extern int fscrypt_inherit_context(struct inode *, struct inode *,
187 void *, bool);
188/* keyinfo.c */
189extern int fscrypt_get_encryption_info(struct inode *);
190extern void fscrypt_put_encryption_info(struct inode *, struct fscrypt_info *);
191
192/* fname.c */
193extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
194 int lookup, struct fscrypt_name *);
195extern void fscrypt_free_filename(struct fscrypt_name *);
196extern u32 fscrypt_fname_encrypted_size(const struct inode *, u32);
197extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
198 struct fscrypt_str *);
199extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
200extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
201 const struct fscrypt_str *, struct fscrypt_str *);
202extern int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *,
203 struct fscrypt_str *);
204#endif
205
206/* crypto.c */
207static inline struct fscrypt_ctx *fscrypt_notsupp_get_ctx(const struct inode *i,
208 gfp_t f)
209{
210 return ERR_PTR(-EOPNOTSUPP);
211}
212
213static inline void fscrypt_notsupp_release_ctx(struct fscrypt_ctx *c)
214{
215 return;
216}
217
218static inline struct page *fscrypt_notsupp_encrypt_page(const struct inode *i,
219 struct page *p,
220 unsigned int len,
221 unsigned int offs,
222 u64 lblk_num, gfp_t f)
223{
224 return ERR_PTR(-EOPNOTSUPP);
225}
226
227static inline int fscrypt_notsupp_decrypt_page(const struct inode *i, struct page *p,
228 unsigned int len, unsigned int offs,
229 u64 lblk_num)
230{
231 return -EOPNOTSUPP;
232}
233
234static inline void fscrypt_notsupp_decrypt_bio_pages(struct fscrypt_ctx *c,
235 struct bio *b)
236{
237 return;
238}
239
240static inline void fscrypt_notsupp_pullback_bio_page(struct page **p, bool b)
241{
242 return;
243}
244
245static inline void fscrypt_notsupp_restore_control_page(struct page *p)
246{
247 return;
248}
249
250static inline int fscrypt_notsupp_zeroout_range(const struct inode *i, pgoff_t p,
251 sector_t s, unsigned int f)
252{
253 return -EOPNOTSUPP;
254}
255
256/* policy.c */
257static inline int fscrypt_notsupp_ioctl_set_policy(struct file *f,
258 const void __user *arg)
259{
260 return -EOPNOTSUPP;
261}
262
263static inline int fscrypt_notsupp_ioctl_get_policy(struct file *f,
264 void __user *arg)
265{
266 return -EOPNOTSUPP;
267}
268
269static inline int fscrypt_notsupp_has_permitted_context(struct inode *p,
270 struct inode *i)
271{
272 return 0;
273}
274
275static inline int fscrypt_notsupp_inherit_context(struct inode *p,
276 struct inode *i, void *v, bool b)
277{
278 return -EOPNOTSUPP;
279}
280
281/* keyinfo.c */
282static inline int fscrypt_notsupp_get_encryption_info(struct inode *i)
283{
284 return -EOPNOTSUPP;
285}
286
287static inline void fscrypt_notsupp_put_encryption_info(struct inode *i,
288 struct fscrypt_info *f)
289{
290 return;
291}
292
293 /* fname.c */
294static inline int fscrypt_notsupp_setup_filename(struct inode *dir,
295 const struct qstr *iname,
296 int lookup, struct fscrypt_name *fname)
297{
298 if (dir->i_sb->s_cop->is_encrypted(dir))
299 return -EOPNOTSUPP;
300
301 memset(fname, 0, sizeof(struct fscrypt_name));
302 fname->usr_fname = iname;
303 fname->disk_name.name = (unsigned char *)iname->name;
304 fname->disk_name.len = iname->len;
305 return 0;
306}
307
308static inline void fscrypt_notsupp_free_filename(struct fscrypt_name *fname)
309{
310 return;
311}
312
313static inline u32 fscrypt_notsupp_fname_encrypted_size(struct inode *i, u32 s)
314{
315 /* never happens */
316 WARN_ON(1);
317 return 0;
318}
319
320static inline int fscrypt_notsupp_fname_alloc_buffer(struct inode *inode,
321 u32 ilen, struct fscrypt_str *crypto_str)
322{
323 return -EOPNOTSUPP;
324}
325
326static inline void fscrypt_notsupp_fname_free_buffer(struct fscrypt_str *c)
327{
328 return;
329}
330
331static inline int fscrypt_notsupp_fname_disk_to_usr(struct inode *inode,
332 u32 hash, u32 minor_hash,
333 const struct fscrypt_str *iname,
334 struct fscrypt_str *oname)
335{
336 return -EOPNOTSUPP;
337}
338
339static inline int fscrypt_notsupp_fname_usr_to_disk(struct inode *inode,
340 const struct qstr *iname,
341 struct fscrypt_str *oname)
342{
343 return -EOPNOTSUPP;
344}
345#endif /* _LINUX_FSCRYPTO_H */