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 16 struct ceph_fs_client; 17 struct ceph_acl_sec_ctx; 18 struct ceph_mds_request; 19 20 struct 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 encrypted 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 */ 34 struct 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 50 struct 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 57 static 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 94 int ceph_base64_encode(const u8 *src, int srclen, char *dst); 95 int ceph_base64_decode(const char *src, int srclen, u8 *dst); 96 97 void ceph_fscrypt_set_ops(struct super_block *sb); 98 99 void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc); 100 101 int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode, 102 struct ceph_acl_sec_ctx *as); 103 void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req, 104 struct ceph_acl_sec_ctx *as); 105 int ceph_encode_encrypted_dname(struct inode *parent, char *buf, int len); 106 107 static inline int ceph_fname_alloc_buffer(struct inode *parent, 108 struct fscrypt_str *fname) 109 { 110 if (!IS_ENCRYPTED(parent)) 111 return 0; 112 return fscrypt_fname_alloc_buffer(NAME_MAX, fname); 113 } 114 115 static inline void ceph_fname_free_buffer(struct inode *parent, 116 struct fscrypt_str *fname) 117 { 118 if (IS_ENCRYPTED(parent)) 119 fscrypt_fname_free_buffer(fname); 120 } 121 122 int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname, 123 struct fscrypt_str *oname, bool *is_nokey); 124 int ceph_fscrypt_prepare_readdir(struct inode *dir); 125 126 static inline unsigned int ceph_fscrypt_blocks(u64 off, u64 len) 127 { 128 /* crypto blocks cannot span more than one page */ 129 BUILD_BUG_ON(CEPH_FSCRYPT_BLOCK_SHIFT > PAGE_SHIFT); 130 131 return ((off+len+CEPH_FSCRYPT_BLOCK_SIZE-1) >> CEPH_FSCRYPT_BLOCK_SHIFT) - 132 (off >> CEPH_FSCRYPT_BLOCK_SHIFT); 133 } 134 135 /* 136 * If we have an encrypted inode then we must adjust the offset and 137 * range of the on-the-wire read to cover an entire encryption block. 138 * The copy will be done using the original offset and length, after 139 * we've decrypted the result. 140 */ 141 static inline void ceph_fscrypt_adjust_off_and_len(struct inode *inode, 142 u64 *off, u64 *len) 143 { 144 if (IS_ENCRYPTED(inode)) { 145 *len = ceph_fscrypt_blocks(*off, *len) * CEPH_FSCRYPT_BLOCK_SIZE; 146 *off &= CEPH_FSCRYPT_BLOCK_MASK; 147 } 148 } 149 150 int ceph_fscrypt_decrypt_block_inplace(const struct inode *inode, 151 struct page *page, unsigned int len, 152 unsigned int offs, u64 lblk_num); 153 int ceph_fscrypt_encrypt_block_inplace(const struct inode *inode, 154 struct page *page, unsigned int len, 155 unsigned int offs, u64 lblk_num); 156 int ceph_fscrypt_decrypt_pages(struct inode *inode, struct page **page, 157 u64 off, int len); 158 int ceph_fscrypt_decrypt_extents(struct inode *inode, struct page **page, 159 u64 off, struct ceph_sparse_extent *map, 160 u32 ext_cnt); 161 int ceph_fscrypt_encrypt_pages(struct inode *inode, struct page **page, u64 off, 162 int len); 163 164 static inline struct page *ceph_fscrypt_pagecache_page(struct page *page) 165 { 166 return fscrypt_is_bounce_page(page) ? fscrypt_pagecache_page(page) : page; 167 } 168 169 #else /* CONFIG_FS_ENCRYPTION */ 170 171 static inline void ceph_fscrypt_set_ops(struct super_block *sb) 172 { 173 } 174 175 static inline void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc) 176 { 177 } 178 179 static inline int ceph_fscrypt_prepare_context(struct inode *dir, 180 struct inode *inode, 181 struct ceph_acl_sec_ctx *as) 182 { 183 if (IS_ENCRYPTED(dir)) 184 return -EOPNOTSUPP; 185 return 0; 186 } 187 188 static inline void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req, 189 struct ceph_acl_sec_ctx *as_ctx) 190 { 191 } 192 193 static inline int ceph_encode_encrypted_dname(struct inode *parent, char *buf, 194 int len) 195 { 196 return len; 197 } 198 199 static inline int ceph_fname_alloc_buffer(struct inode *parent, 200 struct fscrypt_str *fname) 201 { 202 return 0; 203 } 204 205 static inline void ceph_fname_free_buffer(struct inode *parent, 206 struct fscrypt_str *fname) 207 { 208 } 209 210 static inline int ceph_fname_to_usr(const struct ceph_fname *fname, 211 struct fscrypt_str *tname, 212 struct fscrypt_str *oname, bool *is_nokey) 213 { 214 oname->name = fname->name; 215 oname->len = fname->name_len; 216 return 0; 217 } 218 219 static inline int ceph_fscrypt_prepare_readdir(struct inode *dir) 220 { 221 return 0; 222 } 223 224 static inline void ceph_fscrypt_adjust_off_and_len(struct inode *inode, 225 u64 *off, u64 *len) 226 { 227 } 228 229 static inline int ceph_fscrypt_decrypt_block_inplace(const struct inode *inode, 230 struct page *page, unsigned int len, 231 unsigned int offs, u64 lblk_num) 232 { 233 return 0; 234 } 235 236 static inline int ceph_fscrypt_encrypt_block_inplace(const struct inode *inode, 237 struct page *page, unsigned int len, 238 unsigned int offs, u64 lblk_num) 239 { 240 return 0; 241 } 242 243 static inline int ceph_fscrypt_decrypt_pages(struct inode *inode, 244 struct page **page, u64 off, 245 int len) 246 { 247 return 0; 248 } 249 250 static inline int ceph_fscrypt_decrypt_extents(struct inode *inode, 251 struct page **page, u64 off, 252 struct ceph_sparse_extent *map, 253 u32 ext_cnt) 254 { 255 return 0; 256 } 257 258 static inline int ceph_fscrypt_encrypt_pages(struct inode *inode, 259 struct page **page, u64 off, 260 int len) 261 { 262 return 0; 263 } 264 265 static inline struct page *ceph_fscrypt_pagecache_page(struct page *page) 266 { 267 return page; 268 } 269 #endif /* CONFIG_FS_ENCRYPTION */ 270 271 static inline loff_t ceph_fscrypt_page_offset(struct page *page) 272 { 273 return page_offset(ceph_fscrypt_pagecache_page(page)); 274 } 275 276 #endif /* _CEPH_CRYPTO_H */ 277