1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Ceph fscrypt functionality
4 */
5
6#ifndef _CEPH_CRYPTO_H
7#define _CEPH_CRYPTO_H
8
9#include <crypto/sha2.h>
10#include <linux/fscrypt.h>
11
12#define CEPH_FSCRYPT_BLOCK_SHIFT 12
13#define CEPH_FSCRYPT_BLOCK_SIZE (_AC(1, UL) << CEPH_FSCRYPT_BLOCK_SHIFT)
14#define CEPH_FSCRYPT_BLOCK_MASK (~(CEPH_FSCRYPT_BLOCK_SIZE-1))
15
16struct ceph_fs_client;
17struct ceph_acl_sec_ctx;
18struct ceph_mds_request;
19
20struct ceph_fname {
21 struct inode *dir;
22 char *name; // b64 encoded, possibly hashed
23 unsigned char *ctext; // binary crypttext (if any)
24 u32 name_len; // length of name buffer
25 u32 ctext_len; // length of crypttext
26 bool no_copy;
27};
28
29/*
30 * Header for the crypted file when truncating the size, this
31 * will be sent to MDS, and the MDS will update the encrypted
32 * last block and then truncate the size.
33 */
34struct ceph_fscrypt_truncate_size_header {
35 __u8 ver;
36 __u8 compat;
37
38 /*
39 * It will be sizeof(assert_ver + file_offset + block_size)
40 * if the last block is empty when it's located in a file
41 * hole. Or the data_len will plus CEPH_FSCRYPT_BLOCK_SIZE.
42 */
43 __le32 data_len;
44
45 __le64 change_attr;
46 __le64 file_offset;
47 __le32 block_size;
48} __packed;
49
50struct ceph_fscrypt_auth {
51 __le32 cfa_version;
52 __le32 cfa_blob_len;
53 u8 cfa_blob[FSCRYPT_SET_CONTEXT_MAX_SIZE];
54} __packed;
55
56#define CEPH_FSCRYPT_AUTH_VERSION 1
57static inline u32 ceph_fscrypt_auth_len(struct ceph_fscrypt_auth *fa)
58{
59 u32 ctxsize = le32_to_cpu(fa->cfa_blob_len);
60
61 return offsetof(struct ceph_fscrypt_auth, cfa_blob) + ctxsize;
62}
63
64#ifdef CONFIG_FS_ENCRYPTION
65/*
66 * We want to encrypt filenames when creating them, but the encrypted
67 * versions of those names may have illegal characters in them. To mitigate
68 * that, we base64 encode them, but that gives us a result that can exceed
69 * NAME_MAX.
70 *
71 * Follow a similar scheme to fscrypt itself, and cap the filename to a
72 * smaller size. If the ciphertext name is longer than the value below, then
73 * sha256 hash the remaining bytes.
74 *
75 * For the fscrypt_nokey_name struct the dirhash[2] member is useless in ceph
76 * so the corresponding struct will be:
77 *
78 * struct fscrypt_ceph_nokey_name {
79 * u8 bytes[157];
80 * u8 sha256[SHA256_DIGEST_SIZE];
81 * }; // 180 bytes => 240 bytes base64-encoded, which is <= NAME_MAX (255)
82 *
83 * (240 bytes is the maximum size allowed for snapshot names to take into
84 * account the format: '_<SNAPSHOT-NAME>_<INODE-NUMBER>'.)
85 *
86 * Note that for long names that end up having their tail portion hashed, we
87 * must also store the full encrypted name (in the dentry's alternate_name
88 * field).
89 */
90#define CEPH_NOHASH_NAME_MAX (180 - SHA256_DIGEST_SIZE)
91
92#define CEPH_BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)
93
94int ceph_base64_encode(const u8 *src, int srclen, char *dst);
95int ceph_base64_decode(const char *src, int srclen, u8 *dst);
96
97void ceph_fscrypt_set_ops(struct super_block *sb);
98
99void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc);
100
101int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
102 struct ceph_acl_sec_ctx *as);
103void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
104 struct ceph_acl_sec_ctx *as);
105int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
106 char *buf);
107int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry,
108 char *buf);
109
110static inline int ceph_fname_alloc_buffer(struct inode *parent,
111 struct fscrypt_str *fname)
112{
113 if (!IS_ENCRYPTED(parent))
114 return 0;
115 return fscrypt_fname_alloc_buffer(NAME_MAX, crypto_str: fname);
116}
117
118static inline void ceph_fname_free_buffer(struct inode *parent,
119 struct fscrypt_str *fname)
120{
121 if (IS_ENCRYPTED(parent))
122 fscrypt_fname_free_buffer(crypto_str: fname);
123}
124
125int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
126 struct fscrypt_str *oname, bool *is_nokey);
127int ceph_fscrypt_prepare_readdir(struct inode *dir);
128
129static inline unsigned int ceph_fscrypt_blocks(u64 off, u64 len)
130{
131 /* crypto blocks cannot span more than one page */
132 BUILD_BUG_ON(CEPH_FSCRYPT_BLOCK_SHIFT > PAGE_SHIFT);
133
134 return ((off+len+CEPH_FSCRYPT_BLOCK_SIZE-1) >> CEPH_FSCRYPT_BLOCK_SHIFT) -
135 (off >> CEPH_FSCRYPT_BLOCK_SHIFT);
136}
137
138/*
139 * If we have an encrypted inode then we must adjust the offset and
140 * range of the on-the-wire read to cover an entire encryption block.
141 * The copy will be done using the original offset and length, after
142 * we've decrypted the result.
143 */
144static inline void ceph_fscrypt_adjust_off_and_len(struct inode *inode,
145 u64 *off, u64 *len)
146{
147 if (IS_ENCRYPTED(inode)) {
148 *len = ceph_fscrypt_blocks(off: *off, len: *len) * CEPH_FSCRYPT_BLOCK_SIZE;
149 *off &= CEPH_FSCRYPT_BLOCK_MASK;
150 }
151}
152
153int ceph_fscrypt_decrypt_block_inplace(const struct inode *inode,
154 struct page *page, unsigned int len,
155 unsigned int offs, u64 lblk_num);
156int ceph_fscrypt_encrypt_block_inplace(const struct inode *inode,
157 struct page *page, unsigned int len,
158 unsigned int offs, u64 lblk_num,
159 gfp_t gfp_flags);
160int ceph_fscrypt_decrypt_pages(struct inode *inode, struct page **page,
161 u64 off, int len);
162int ceph_fscrypt_decrypt_extents(struct inode *inode, struct page **page,
163 u64 off, struct ceph_sparse_extent *map,
164 u32 ext_cnt);
165int ceph_fscrypt_encrypt_pages(struct inode *inode, struct page **page, u64 off,
166 int len, gfp_t gfp);
167
168static inline struct page *ceph_fscrypt_pagecache_page(struct page *page)
169{
170 return fscrypt_is_bounce_page(page) ? fscrypt_pagecache_page(bounce_page: page) : page;
171}
172
173#else /* CONFIG_FS_ENCRYPTION */
174
175static inline void ceph_fscrypt_set_ops(struct super_block *sb)
176{
177}
178
179static inline void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc)
180{
181}
182
183static inline int ceph_fscrypt_prepare_context(struct inode *dir,
184 struct inode *inode,
185 struct ceph_acl_sec_ctx *as)
186{
187 if (IS_ENCRYPTED(dir))
188 return -EOPNOTSUPP;
189 return 0;
190}
191
192static inline void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
193 struct ceph_acl_sec_ctx *as_ctx)
194{
195}
196
197static inline int ceph_encode_encrypted_dname(struct inode *parent,
198 struct qstr *d_name, char *buf)
199{
200 memcpy(buf, d_name->name, d_name->len);
201 return d_name->len;
202}
203
204static inline int ceph_encode_encrypted_fname(struct inode *parent,
205 struct dentry *dentry, char *buf)
206{
207 return -EOPNOTSUPP;
208}
209
210static inline int ceph_fname_alloc_buffer(struct inode *parent,
211 struct fscrypt_str *fname)
212{
213 return 0;
214}
215
216static inline void ceph_fname_free_buffer(struct inode *parent,
217 struct fscrypt_str *fname)
218{
219}
220
221static inline int ceph_fname_to_usr(const struct ceph_fname *fname,
222 struct fscrypt_str *tname,
223 struct fscrypt_str *oname, bool *is_nokey)
224{
225 oname->name = fname->name;
226 oname->len = fname->name_len;
227 return 0;
228}
229
230static inline int ceph_fscrypt_prepare_readdir(struct inode *dir)
231{
232 return 0;
233}
234
235static inline void ceph_fscrypt_adjust_off_and_len(struct inode *inode,
236 u64 *off, u64 *len)
237{
238}
239
240static inline int ceph_fscrypt_decrypt_block_inplace(const struct inode *inode,
241 struct page *page, unsigned int len,
242 unsigned int offs, u64 lblk_num)
243{
244 return 0;
245}
246
247static inline int ceph_fscrypt_encrypt_block_inplace(const struct inode *inode,
248 struct page *page, unsigned int len,
249 unsigned int offs, u64 lblk_num,
250 gfp_t gfp_flags)
251{
252 return 0;
253}
254
255static inline int ceph_fscrypt_decrypt_pages(struct inode *inode,
256 struct page **page, u64 off,
257 int len)
258{
259 return 0;
260}
261
262static inline int ceph_fscrypt_decrypt_extents(struct inode *inode,
263 struct page **page, u64 off,
264 struct ceph_sparse_extent *map,
265 u32 ext_cnt)
266{
267 return 0;
268}
269
270static inline int ceph_fscrypt_encrypt_pages(struct inode *inode,
271 struct page **page, u64 off,
272 int len, gfp_t gfp)
273{
274 return 0;
275}
276
277static inline struct page *ceph_fscrypt_pagecache_page(struct page *page)
278{
279 return page;
280}
281#endif /* CONFIG_FS_ENCRYPTION */
282
283static inline loff_t ceph_fscrypt_page_offset(struct page *page)
284{
285 return page_offset(page: ceph_fscrypt_pagecache_page(page));
286}
287
288#endif /* _CEPH_CRYPTO_H */
289

source code of linux/fs/ceph/crypto.h