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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
46f47e48 EB |
2 | /* |
3 | * fscrypt_supp.h | |
4 | * | |
734f0d24 | 5 | * Do not include this file directly. Use fscrypt.h instead! |
46f47e48 | 6 | */ |
734f0d24 DC |
7 | #ifndef _LINUX_FSCRYPT_H |
8 | #error "Incorrect include of linux/fscrypt_supp.h!" | |
9 | #endif | |
46f47e48 EB |
10 | |
11 | #ifndef _LINUX_FSCRYPT_SUPP_H | |
12 | #define _LINUX_FSCRYPT_SUPP_H | |
13 | ||
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14 | #include <linux/mm.h> |
15 | #include <linux/slab.h> | |
16 | ||
bdd23476 EB |
17 | /* |
18 | * fscrypt superblock flags | |
19 | */ | |
20 | #define FS_CFLG_OWN_PAGES (1U << 1) | |
21 | ||
22 | /* | |
23 | * crypto operations for filesystems | |
24 | */ | |
25 | struct fscrypt_operations { | |
26 | unsigned int flags; | |
27 | const char *key_prefix; | |
28 | int (*get_context)(struct inode *, void *, size_t); | |
29 | int (*set_context)(struct inode *, const void *, size_t, void *); | |
30 | bool (*dummy_context)(struct inode *); | |
31 | bool (*empty_dir)(struct inode *); | |
32 | unsigned (*max_namelen)(struct inode *); | |
33 | }; | |
34 | ||
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35 | struct fscrypt_ctx { |
36 | union { | |
37 | struct { | |
38 | struct page *bounce_page; /* Ciphertext page */ | |
39 | struct page *control_page; /* Original page */ | |
40 | } w; | |
41 | struct { | |
42 | struct bio *bio; | |
43 | struct work_struct work; | |
44 | } r; | |
45 | struct list_head free_list; /* Free list */ | |
46 | }; | |
47 | u8 flags; /* Flags */ | |
48 | }; | |
49 | ||
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50 | static inline bool fscrypt_has_encryption_key(const struct inode *inode) |
51 | { | |
52 | return (inode->i_crypt_info != NULL); | |
53 | } | |
54 | ||
1493651b EB |
55 | static inline bool fscrypt_dummy_context_enabled(struct inode *inode) |
56 | { | |
57 | return inode->i_sb->s_cop->dummy_context && | |
58 | inode->i_sb->s_cop->dummy_context(inode); | |
59 | } | |
60 | ||
46f47e48 | 61 | /* crypto.c */ |
46f47e48 EB |
62 | extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t); |
63 | extern void fscrypt_release_ctx(struct fscrypt_ctx *); | |
64 | extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *, | |
65 | unsigned int, unsigned int, | |
66 | u64, gfp_t); | |
67 | extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int, | |
68 | unsigned int, u64); | |
4fd4b15c EB |
69 | |
70 | static inline struct page *fscrypt_control_page(struct page *page) | |
71 | { | |
72 | return ((struct fscrypt_ctx *)page_private(page))->w.control_page; | |
73 | } | |
74 | ||
46f47e48 EB |
75 | extern void fscrypt_restore_control_page(struct page *); |
76 | ||
77 | extern const struct dentry_operations fscrypt_d_ops; | |
78 | ||
79 | static inline void fscrypt_set_d_op(struct dentry *dentry) | |
80 | { | |
81 | d_set_d_op(dentry, &fscrypt_d_ops); | |
82 | } | |
83 | ||
84 | static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry) | |
85 | { | |
86 | spin_lock(&dentry->d_lock); | |
87 | dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY; | |
88 | spin_unlock(&dentry->d_lock); | |
89 | } | |
90 | ||
91 | /* policy.c */ | |
92 | extern int fscrypt_ioctl_set_policy(struct file *, const void __user *); | |
93 | extern int fscrypt_ioctl_get_policy(struct file *, void __user *); | |
94 | extern int fscrypt_has_permitted_context(struct inode *, struct inode *); | |
95 | extern int fscrypt_inherit_context(struct inode *, struct inode *, | |
96 | void *, bool); | |
97 | /* keyinfo.c */ | |
98 | extern int fscrypt_get_encryption_info(struct inode *); | |
3d204e24 | 99 | extern void fscrypt_put_encryption_info(struct inode *); |
46f47e48 EB |
100 | |
101 | /* fname.c */ | |
102 | extern int fscrypt_setup_filename(struct inode *, const struct qstr *, | |
103 | int lookup, struct fscrypt_name *); | |
27e47a63 EB |
104 | |
105 | static inline void fscrypt_free_filename(struct fscrypt_name *fname) | |
106 | { | |
107 | kfree(fname->crypto_buf.name); | |
108 | } | |
109 | ||
46f47e48 EB |
110 | extern int fscrypt_fname_alloc_buffer(const struct inode *, u32, |
111 | struct fscrypt_str *); | |
112 | extern void fscrypt_fname_free_buffer(struct fscrypt_str *); | |
113 | extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32, | |
114 | const struct fscrypt_str *, struct fscrypt_str *); | |
46f47e48 | 115 | |
17159420 EB |
116 | #define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE 32 |
117 | ||
118 | /* Extracts the second-to-last ciphertext block; see explanation below */ | |
119 | #define FSCRYPT_FNAME_DIGEST(name, len) \ | |
120 | ((name) + round_down((len) - FS_CRYPTO_BLOCK_SIZE - 1, \ | |
121 | FS_CRYPTO_BLOCK_SIZE)) | |
122 | ||
123 | #define FSCRYPT_FNAME_DIGEST_SIZE FS_CRYPTO_BLOCK_SIZE | |
124 | ||
125 | /** | |
126 | * fscrypt_digested_name - alternate identifier for an on-disk filename | |
127 | * | |
128 | * When userspace lists an encrypted directory without access to the key, | |
129 | * filenames whose ciphertext is longer than FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE | |
130 | * bytes are shown in this abbreviated form (base64-encoded) rather than as the | |
131 | * full ciphertext (base64-encoded). This is necessary to allow supporting | |
132 | * filenames up to NAME_MAX bytes, since base64 encoding expands the length. | |
133 | * | |
134 | * To make it possible for filesystems to still find the correct directory entry | |
135 | * despite not knowing the full on-disk name, we encode any filesystem-specific | |
136 | * 'hash' and/or 'minor_hash' which the filesystem may need for its lookups, | |
137 | * followed by the second-to-last ciphertext block of the filename. Due to the | |
138 | * use of the CBC-CTS encryption mode, the second-to-last ciphertext block | |
139 | * depends on the full plaintext. (Note that ciphertext stealing causes the | |
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140 | * last two blocks to appear "flipped".) This makes accidental collisions very |
141 | * unlikely: just a 1 in 2^128 chance for two filenames to collide even if they | |
142 | * share the same filesystem-specific hashes. | |
17159420 | 143 | * |
6f9d696f EB |
144 | * However, this scheme isn't immune to intentional collisions, which can be |
145 | * created by anyone able to create arbitrary plaintext filenames and view them | |
146 | * without the key. Making the "digest" be a real cryptographic hash like | |
147 | * SHA-256 over the full ciphertext would prevent this, although it would be | |
148 | * less efficient and harder to implement, especially since the filesystem would | |
149 | * need to calculate it for each directory entry examined during a search. | |
17159420 EB |
150 | */ |
151 | struct fscrypt_digested_name { | |
152 | u32 hash; | |
153 | u32 minor_hash; | |
154 | u8 digest[FSCRYPT_FNAME_DIGEST_SIZE]; | |
155 | }; | |
156 | ||
157 | /** | |
158 | * fscrypt_match_name() - test whether the given name matches a directory entry | |
159 | * @fname: the name being searched for | |
160 | * @de_name: the name from the directory entry | |
161 | * @de_name_len: the length of @de_name in bytes | |
162 | * | |
163 | * Normally @fname->disk_name will be set, and in that case we simply compare | |
164 | * that to the name stored in the directory entry. The only exception is that | |
165 | * if we don't have the key for an encrypted directory and a filename in it is | |
166 | * very long, then we won't have the full disk_name and we'll instead need to | |
167 | * match against the fscrypt_digested_name. | |
168 | * | |
169 | * Return: %true if the name matches, otherwise %false. | |
170 | */ | |
171 | static inline bool fscrypt_match_name(const struct fscrypt_name *fname, | |
172 | const u8 *de_name, u32 de_name_len) | |
173 | { | |
174 | if (unlikely(!fname->disk_name.name)) { | |
175 | const struct fscrypt_digested_name *n = | |
176 | (const void *)fname->crypto_buf.name; | |
177 | if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_')) | |
178 | return false; | |
179 | if (de_name_len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) | |
180 | return false; | |
181 | return !memcmp(FSCRYPT_FNAME_DIGEST(de_name, de_name_len), | |
182 | n->digest, FSCRYPT_FNAME_DIGEST_SIZE); | |
183 | } | |
184 | ||
185 | if (de_name_len != fname->disk_name.len) | |
186 | return false; | |
187 | return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len); | |
188 | } | |
189 | ||
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190 | /* bio.c */ |
191 | extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *); | |
192 | extern void fscrypt_pullback_bio_page(struct page **, bool); | |
193 | extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t, | |
194 | unsigned int); | |
195 | ||
efcc7ae2 EB |
196 | /* hooks.c */ |
197 | extern int fscrypt_file_open(struct inode *inode, struct file *filp); | |
0ea87a96 | 198 | extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir); |
94b26f36 EB |
199 | extern int __fscrypt_prepare_rename(struct inode *old_dir, |
200 | struct dentry *old_dentry, | |
201 | struct inode *new_dir, | |
202 | struct dentry *new_dentry, | |
203 | unsigned int flags); | |
32c3cf02 | 204 | extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry); |
76e81d6d EB |
205 | extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, |
206 | unsigned int max_len, | |
207 | struct fscrypt_str *disk_link); | |
208 | extern int __fscrypt_encrypt_symlink(struct inode *inode, const char *target, | |
209 | unsigned int len, | |
210 | struct fscrypt_str *disk_link); | |
3b0d8837 EB |
211 | extern const char *fscrypt_get_symlink(struct inode *inode, const void *caddr, |
212 | unsigned int max_size, | |
213 | struct delayed_call *done); | |
efcc7ae2 | 214 | |
46f47e48 | 215 | #endif /* _LINUX_FSCRYPT_SUPP_H */ |