fs/ceph/crypto.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * The base64 encode/decode code was copied from fscrypt:
   4  * Copyright (C) 2015, Google, Inc.
   5  * Copyright (C) 2015, Motorola Mobility
   6  * Written by Uday Savagaonkar, 2014.
   7  * Modified by Jaegeuk Kim, 2015.
   8  */
   9 #include <linux/ceph/ceph_debug.h>
  10 #include <linux/xattr.h>
  11 #include <linux/fscrypt.h>
  12 #include <linux/ceph/striper.h>
  13
  14 #include "super.h"
  15 #include "mds_client.h"
  16 #include "crypto.h"
  17
  18 /*
  19  * The base64url encoding used by fscrypt includes the '_' character, which may
  20  * cause problems in snapshot names (which can not start with '_').  Thus, we
  21  * used the base64 encoding defined for IMAP mailbox names (RFC 3501) instead,
  22  * which replaces '-' and '_' by '+' and ','.
  23  */
  24 static const char base64_table[65] =
  25         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
  26
  27 int ceph_base64_encode(const u8 *src, int srclen, char *dst)
  28 {
  29         u32 ac = 0;
  30         int bits = 0;
  31         int i;
  32         char *cp = dst;
  33
  34         for (i = 0; i < srclen; i++) {
  35                 ac = (ac << 8) | src[i];
  36                 bits += 8;
  37                 do {
  38                         bits -= 6;
  39                         *cp++ = base64_table[(ac >> bits) & 0x3f];
  40                 } while (bits >= 6);
  41         }
  42         if (bits)
  43                 *cp++ = base64_table[(ac << (6 - bits)) & 0x3f];
  44         return cp - dst;
  45 }
  46
  47 int ceph_base64_decode(const char *src, int srclen, u8 *dst)
  48 {
  49         u32 ac = 0;
  50         int bits = 0;
  51         int i;
  52         u8 *bp = dst;
  53
  54         for (i = 0; i < srclen; i++) {
  55                 const char *p = strchr(base64_table, src[i]);
  56
  57                 if (p == NULL || src[i] == 0)
  58                         return -1;
  59                 ac = (ac << 6) | (p - base64_table);
  60                 bits += 6;
  61                 if (bits >= 8) {
  62                         bits -= 8;
  63                         *bp++ = (u8)(ac >> bits);
  64                 }
  65         }
  66         if (ac & ((1 << bits) - 1))
  67                 return -1;
  68         return bp - dst;
  69 }
  70
  71 static int ceph_crypt_get_context(struct inode *inode, void *ctx, size_t len)
  72 {
  73         struct ceph_inode_info *ci = ceph_inode(inode);
  74         struct ceph_fscrypt_auth *cfa = (struct ceph_fscrypt_auth *)ci->fscrypt_auth;
  75         u32 ctxlen;
  76
  77         /* Non existent or too short? */
  78         if (!cfa || (ci->fscrypt_auth_len < (offsetof(struct ceph_fscrypt_auth, cfa_blob) + 1)))
  79                 return -ENOBUFS;
  80
  81         /* Some format we don't recognize? */
  82         if (le32_to_cpu(cfa->cfa_version) != CEPH_FSCRYPT_AUTH_VERSION)
  83                 return -ENOBUFS;
  84
  85         ctxlen = le32_to_cpu(cfa->cfa_blob_len);
  86         if (len < ctxlen)
  87                 return -ERANGE;
  88
  89         memcpy(ctx, cfa->cfa_blob, ctxlen);
  90         return ctxlen;
  91 }
  92
  93 static int ceph_crypt_set_context(struct inode *inode, const void *ctx,
  94                                   size_t len, void *fs_data)
  95 {
  96         int ret;
  97         struct iattr attr = { };
  98         struct ceph_iattr cia = { };
  99         struct ceph_fscrypt_auth *cfa;
 100
 101         WARN_ON_ONCE(fs_data);
 102
 103         if (len > FSCRYPT_SET_CONTEXT_MAX_SIZE)
 104                 return -EINVAL;
 105
 106         cfa = kzalloc(sizeof(*cfa), GFP_KERNEL);
 107         if (!cfa)
 108                 return -ENOMEM;
 109
 110         cfa->cfa_version = cpu_to_le32(CEPH_FSCRYPT_AUTH_VERSION);
 111         cfa->cfa_blob_len = cpu_to_le32(len);
 112         memcpy(cfa->cfa_blob, ctx, len);
 113
 114         cia.fscrypt_auth = cfa;
 115
 116         ret = __ceph_setattr(inode, &attr, &cia);
 117         if (ret == 0)
 118                 inode_set_flags(inode, S_ENCRYPTED, S_ENCRYPTED);
 119         kfree(cia.fscrypt_auth);
 120         return ret;
 121 }
 122
 123 static bool ceph_crypt_empty_dir(struct inode *inode)
 124 {
 125         struct ceph_inode_info *ci = ceph_inode(inode);
 126
 127         return ci->i_rsubdirs + ci->i_rfiles == 1;
 128 }
 129
 130 static const union fscrypt_policy *ceph_get_dummy_policy(struct super_block *sb)
 131 {
 132         return ceph_sb_to_client(sb)->fsc_dummy_enc_policy.policy;
 133 }
 134
 135 static struct fscrypt_operations ceph_fscrypt_ops = {
 136         .get_context            = ceph_crypt_get_context,
 137         .set_context            = ceph_crypt_set_context,
 138         .get_dummy_policy       = ceph_get_dummy_policy,
 139         .empty_dir              = ceph_crypt_empty_dir,
 140 };
 141
 142 void ceph_fscrypt_set_ops(struct super_block *sb)
 143 {
 144         fscrypt_set_ops(sb, &ceph_fscrypt_ops);
 145 }
 146
 147 void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc)
 148 {
 149         fscrypt_free_dummy_policy(&fsc->fsc_dummy_enc_policy);
 150 }
 151
 152 int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
 153                                  struct ceph_acl_sec_ctx *as)
 154 {
 155         int ret, ctxsize;
 156         bool encrypted = false;
 157         struct ceph_inode_info *ci = ceph_inode(inode);
 158
 159         ret = fscrypt_prepare_new_inode(dir, inode, &encrypted);
 160         if (ret)
 161                 return ret;
 162         if (!encrypted)
 163                 return 0;
 164
 165         as->fscrypt_auth = kzalloc(sizeof(*as->fscrypt_auth), GFP_KERNEL);
 166         if (!as->fscrypt_auth)
 167                 return -ENOMEM;
 168
 169         ctxsize = fscrypt_context_for_new_inode(as->fscrypt_auth->cfa_blob,
 170                                                 inode);
 171         if (ctxsize < 0)
 172                 return ctxsize;
 173
 174         as->fscrypt_auth->cfa_version = cpu_to_le32(CEPH_FSCRYPT_AUTH_VERSION);
 175         as->fscrypt_auth->cfa_blob_len = cpu_to_le32(ctxsize);
 176
 177         WARN_ON_ONCE(ci->fscrypt_auth);
 178         kfree(ci->fscrypt_auth);
 179         ci->fscrypt_auth_len = ceph_fscrypt_auth_len(as->fscrypt_auth);
 180         ci->fscrypt_auth = kmemdup(as->fscrypt_auth, ci->fscrypt_auth_len,
 181                                    GFP_KERNEL);
 182         if (!ci->fscrypt_auth)
 183                 return -ENOMEM;
 184
 185         inode->i_flags |= S_ENCRYPTED;
 186
 187         return 0;
 188 }
 189
 190 void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
 191                                 struct ceph_acl_sec_ctx *as)
 192 {
 193         swap(req->r_fscrypt_auth, as->fscrypt_auth);
 194 }
 195
 196 /*
 197  * User-created snapshots can't start with '_'.  Snapshots that start with this
 198  * character are special (hint: there aren't real snapshots) and use the
 199  * following format:
 200  *
 201  *   _<SNAPSHOT-NAME>_<INODE-NUMBER>
 202  *
 203  * where:
 204  *  - <SNAPSHOT-NAME> - the real snapshot name that may need to be decrypted,
 205  *  - <INODE-NUMBER> - the inode number (in decimal) for the actual snapshot
 206  *
 207  * This function parses these snapshot names and returns the inode
 208  * <INODE-NUMBER>.  'name_len' will also bet set with the <SNAPSHOT-NAME>
 209  * length.
 210  */
 211 static struct inode *parse_longname(const struct inode *parent,
 212                                     const char *name, int *name_len)
 213 {
 214         struct inode *dir = NULL;
 215         struct ceph_vino vino = { .snap = CEPH_NOSNAP };
 216         char *inode_number;
 217         char *name_end;
 218         int orig_len = *name_len;
 219         int ret = -EIO;
 220
 221         /* Skip initial '_' */
 222         name++;
 223         name_end = strrchr(name, '_');
 224         if (!name_end) {
 225                 dout("Failed to parse long snapshot name: %s\n", name);
 226                 return ERR_PTR(-EIO);
 227         }
 228         *name_len = (name_end - name);
 229         if (*name_len <= 0) {
 230                 pr_err("Failed to parse long snapshot name\n");
 231                 return ERR_PTR(-EIO);
 232         }
 233
 234         /* Get the inode number */
 235         inode_number = kmemdup_nul(name_end + 1,
 236                                    orig_len - *name_len - 2,
 237                                    GFP_KERNEL);
 238         if (!inode_number)
 239                 return ERR_PTR(-ENOMEM);
 240         ret = kstrtou64(inode_number, 10, &vino.ino);
 241         if (ret) {
 242                 dout("Failed to parse inode number: %s\n", name);
 243                 dir = ERR_PTR(ret);
 244                 goto out;
 245         }
 246
 247         /* And finally the inode */
 248         dir = ceph_find_inode(parent->i_sb, vino);
 249         if (!dir) {
 250                 /* This can happen if we're not mounting cephfs on the root */
 251                 dir = ceph_get_inode(parent->i_sb, vino, NULL);
 252                 if (!dir)
 253                         dir = ERR_PTR(-ENOENT);
 254         }
 255         if (IS_ERR(dir))
 256                 dout("Can't find inode %s (%s)\n", inode_number, name);
 257
 258 out:
 259         kfree(inode_number);
 260         return dir;
 261 }
 262
 263 int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
 264                                 char *buf)
 265 {
 266         struct inode *dir = parent;
 267         struct qstr iname;
 268         u32 len;
 269         int name_len;
 270         int elen;
 271         int ret;
 272         u8 *cryptbuf = NULL;
 273
 274         iname.name = d_name->name;
 275         name_len = d_name->len;
 276
 277         /* Handle the special case of snapshot names that start with '_' */
 278         if ((ceph_snap(dir) == CEPH_SNAPDIR) && (name_len > 0) &&
 279             (iname.name[0] == '_')) {
 280                 dir = parse_longname(parent, iname.name, &name_len);
 281                 if (IS_ERR(dir))
 282                         return PTR_ERR(dir);
 283                 iname.name++; /* skip initial '_' */
 284         }
 285         iname.len = name_len;
 286
 287         if (!fscrypt_has_encryption_key(dir)) {
 288                 memcpy(buf, d_name->name, d_name->len);
 289                 elen = d_name->len;
 290                 goto out;
 291         }
 292
 293         /*
 294          * Convert cleartext d_name to ciphertext. If result is longer than
 295          * CEPH_NOHASH_NAME_MAX, sha256 the remaining bytes
 296          *
 297          * See: fscrypt_setup_filename
 298          */
 299         if (!fscrypt_fname_encrypted_size(dir, iname.len, NAME_MAX, &len)) {
 300                 elen = -ENAMETOOLONG;
 301                 goto out;
 302         }
 303
 304         /* Allocate a buffer appropriate to hold the result */
 305         cryptbuf = kmalloc(len > CEPH_NOHASH_NAME_MAX ? NAME_MAX : len,
 306                            GFP_KERNEL);
 307         if (!cryptbuf) {
 308                 elen = -ENOMEM;
 309                 goto out;
 310         }
 311
 312         ret = fscrypt_fname_encrypt(dir, &iname, cryptbuf, len);
 313         if (ret) {
 314                 elen = ret;
 315                 goto out;
 316         }
 317
 318         /* hash the end if the name is long enough */
 319         if (len > CEPH_NOHASH_NAME_MAX) {
 320                 u8 hash[SHA256_DIGEST_SIZE];
 321                 u8 *extra = cryptbuf + CEPH_NOHASH_NAME_MAX;
 322
 323                 /*
 324                  * hash the extra bytes and overwrite crypttext beyond that
 325                  * point with it
 326                  */
 327                 sha256(extra, len - CEPH_NOHASH_NAME_MAX, hash);
 328                 memcpy(extra, hash, SHA256_DIGEST_SIZE);
 329                 len = CEPH_NOHASH_NAME_MAX + SHA256_DIGEST_SIZE;
 330         }
 331
 332         /* base64 encode the encrypted name */
 333         elen = ceph_base64_encode(cryptbuf, len, buf);
 334         dout("base64-encoded ciphertext name = %.*s\n", elen, buf);
 335
 336         /* To understand the 240 limit, see CEPH_NOHASH_NAME_MAX comments */
 337         WARN_ON(elen > 240);
 338         if ((elen > 0) && (dir != parent)) {
 339                 char tmp_buf[NAME_MAX];
 340
 341                 elen = snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld",
 342                                 elen, buf, dir->i_ino);
 343                 memcpy(buf, tmp_buf, elen);
 344         }
 345
 346 out:
 347         kfree(cryptbuf);
 348         if (dir != parent) {
 349                 if ((dir->i_state & I_NEW))
 350                         discard_new_inode(dir);
 351                 else
 352                         iput(dir);
 353         }
 354         return elen;
 355 }
 356
 357 int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry,
 358                                 char *buf)
 359 {
 360         WARN_ON_ONCE(!fscrypt_has_encryption_key(parent));
 361
 362         return ceph_encode_encrypted_dname(parent, &dentry->d_name, buf);
 363 }
 364
 365 /**
 366  * ceph_fname_to_usr - convert a filename for userland presentation
 367  * @fname: ceph_fname to be converted
 368  * @tname: temporary name buffer to use for conversion (may be NULL)
 369  * @oname: where converted name should be placed
 370  * @is_nokey: set to true if key wasn't available during conversion (may be NULL)
 371  *
 372  * Given a filename (usually from the MDS), format it for presentation to
 373  * userland. If @parent is not encrypted, just pass it back as-is.
 374  *
 375  * Otherwise, base64 decode the string, and then ask fscrypt to format it
 376  * for userland presentation.
 377  *
 378  * Returns 0 on success or negative error code on error.
 379  */
 380 int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
 381                       struct fscrypt_str *oname, bool *is_nokey)
 382 {
 383         struct inode *dir = fname->dir;
 384         struct fscrypt_str _tname = FSTR_INIT(NULL, 0);
 385         struct fscrypt_str iname;
 386         char *name = fname->name;
 387         int name_len = fname->name_len;
 388         int ret;
 389
 390         /* Sanity check that the resulting name will fit in the buffer */
 391         if (fname->name_len > NAME_MAX || fname->ctext_len > NAME_MAX)
 392                 return -EIO;
 393
 394         /* Handle the special case of snapshot names that start with '_' */
 395         if ((ceph_snap(dir) == CEPH_SNAPDIR) && (name_len > 0) &&
 396             (name[0] == '_')) {
 397                 dir = parse_longname(dir, name, &name_len);
 398                 if (IS_ERR(dir))
 399                         return PTR_ERR(dir);
 400                 name++; /* skip initial '_' */
 401         }
 402
 403         if (!IS_ENCRYPTED(dir)) {
 404                 oname->name = fname->name;
 405                 oname->len = fname->name_len;
 406                 ret = 0;
 407                 goto out_inode;
 408         }
 409
 410         ret = ceph_fscrypt_prepare_readdir(dir);
 411         if (ret)
 412                 goto out_inode;
 413
 414         /*
 415          * Use the raw dentry name as sent by the MDS instead of
 416          * generating a nokey name via fscrypt.
 417          */
 418         if (!fscrypt_has_encryption_key(dir)) {
 419                 if (fname->no_copy)
 420                         oname->name = fname->name;
 421                 else
 422                         memcpy(oname->name, fname->name, fname->name_len);
 423                 oname->len = fname->name_len;
 424                 if (is_nokey)
 425                         *is_nokey = true;
 426                 ret = 0;
 427                 goto out_inode;
 428         }
 429
 430         if (fname->ctext_len == 0) {
 431                 int declen;
 432
 433                 if (!tname) {
 434                         ret = fscrypt_fname_alloc_buffer(NAME_MAX, &_tname);
 435                         if (ret)
 436                                 goto out_inode;
 437                         tname = &_tname;
 438                 }
 439
 440                 declen = ceph_base64_decode(name, name_len, tname->name);
 441                 if (declen <= 0) {
 442                         ret = -EIO;
 443                         goto out;
 444                 }
 445                 iname.name = tname->name;
 446                 iname.len = declen;
 447         } else {
 448                 iname.name = fname->ctext;
 449                 iname.len = fname->ctext_len;
 450         }
 451
 452         ret = fscrypt_fname_disk_to_usr(dir, 0, 0, &iname, oname);
 453         if (!ret && (dir != fname->dir)) {
 454                 char tmp_buf[CEPH_BASE64_CHARS(NAME_MAX)];
 455
 456                 name_len = snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld",
 457                                     oname->len, oname->name, dir->i_ino);
 458                 memcpy(oname->name, tmp_buf, name_len);
 459                 oname->len = name_len;
 460         }
 461
 462 out:
 463         fscrypt_fname_free_buffer(&_tname);
 464 out_inode:
 465         if ((dir != fname->dir) && !IS_ERR(dir)) {
 466                 if ((dir->i_state & I_NEW))
 467                         discard_new_inode(dir);
 468                 else
 469                         iput(dir);
 470         }
 471         return ret;
 472 }
 473
 474 /**
 475  * ceph_fscrypt_prepare_readdir - simple __fscrypt_prepare_readdir() wrapper
 476  * @dir: directory inode for readdir prep
 477  *
 478  * Simple wrapper around __fscrypt_prepare_readdir() that will mark directory as
 479  * non-complete if this call results in having the directory unlocked.
 480  *
 481  * Returns:
 482  *     1 - if directory was locked and key is now loaded (i.e. dir is unlocked)
 483  *     0 - if directory is still locked
 484  *   < 0 - if __fscrypt_prepare_readdir() fails
 485  */
 486 int ceph_fscrypt_prepare_readdir(struct inode *dir)
 487 {
 488         bool had_key = fscrypt_has_encryption_key(dir);
 489         int err;
 490
 491         if (!IS_ENCRYPTED(dir))
 492                 return 0;
 493
 494         err = __fscrypt_prepare_readdir(dir);
 495         if (err)
 496                 return err;
 497         if (!had_key && fscrypt_has_encryption_key(dir)) {
 498                 /* directory just got unlocked, mark it as not complete */
 499                 ceph_dir_clear_complete(dir);
 500                 return 1;
 501         }
 502         return 0;
 503 }
 504
 505 int ceph_fscrypt_decrypt_block_inplace(const struct inode *inode,
 506                                   struct page *page, unsigned int len,
 507                                   unsigned int offs, u64 lblk_num)
 508 {
 509         dout("%s: len %u offs %u blk %llu\n", __func__, len, offs, lblk_num);
 510         return fscrypt_decrypt_block_inplace(inode, page, len, offs, lblk_num);
 511 }
 512
 513 int ceph_fscrypt_encrypt_block_inplace(const struct inode *inode,
 514                                   struct page *page, unsigned int len,
 515                                   unsigned int offs, u64 lblk_num,
 516                                   gfp_t gfp_flags)
 517 {
 518         dout("%s: len %u offs %u blk %llu\n", __func__, len, offs, lblk_num);
 519         return fscrypt_encrypt_block_inplace(inode, page, len, offs, lblk_num,
 520                                              gfp_flags);
 521 }
 522
 523 /**
 524  * ceph_fscrypt_decrypt_pages - decrypt an array of pages
 525  * @inode: pointer to inode associated with these pages
 526  * @page: pointer to page array
 527  * @off: offset into the file that the read data starts
 528  * @len: max length to decrypt
 529  *
 530  * Decrypt an array of fscrypt'ed pages and return the amount of
 531  * data decrypted. Any data in the page prior to the start of the
 532  * first complete block in the read is ignored. Any incomplete
 533  * crypto blocks at the end of the array are ignored (and should
 534  * probably be zeroed by the caller).
 535  *
 536  * Returns the length of the decrypted data or a negative errno.
 537  */
 538 int ceph_fscrypt_decrypt_pages(struct inode *inode, struct page **page,
 539                                u64 off, int len)
 540 {
 541         int i, num_blocks;
 542         u64 baseblk = off >> CEPH_FSCRYPT_BLOCK_SHIFT;
 543         int ret = 0;
 544
 545         /*
 546          * We can't deal with partial blocks on an encrypted file, so mask off
 547          * the last bit.
 548          */
 549         num_blocks = ceph_fscrypt_blocks(off, len & CEPH_FSCRYPT_BLOCK_MASK);
 550
 551         /* Decrypt each block */
 552         for (i = 0; i < num_blocks; ++i) {
 553                 int blkoff = i << CEPH_FSCRYPT_BLOCK_SHIFT;
 554                 int pgidx = blkoff >> PAGE_SHIFT;
 555                 unsigned int pgoffs = offset_in_page(blkoff);
 556                 int fret;
 557
 558                 fret = ceph_fscrypt_decrypt_block_inplace(inode, page[pgidx],
 559                                 CEPH_FSCRYPT_BLOCK_SIZE, pgoffs,
 560                                 baseblk + i);
 561                 if (fret < 0) {
 562                         if (ret == 0)
 563                                 ret = fret;
 564                         break;
 565                 }
 566                 ret += CEPH_FSCRYPT_BLOCK_SIZE;
 567         }
 568         return ret;
 569 }
 570
 571 /**
 572  * ceph_fscrypt_decrypt_extents: decrypt received extents in given buffer
 573  * @inode: inode associated with pages being decrypted
 574  * @page: pointer to page array
 575  * @off: offset into the file that the data in page[0] starts
 576  * @map: pointer to extent array
 577  * @ext_cnt: length of extent array
 578  *
 579  * Given an extent map and a page array, decrypt the received data in-place,
 580  * skipping holes. Returns the offset into buffer of end of last decrypted
 581  * block.
 582  */
 583 int ceph_fscrypt_decrypt_extents(struct inode *inode, struct page **page,
 584                                  u64 off, struct ceph_sparse_extent *map,
 585                                  u32 ext_cnt)
 586 {
 587         int i, ret = 0;
 588         struct ceph_inode_info *ci = ceph_inode(inode);
 589         u64 objno, objoff;
 590         u32 xlen;
 591
 592         /* Nothing to do for empty array */
 593         if (ext_cnt == 0) {
 594                 dout("%s: empty array, ret 0\n", __func__);
 595                 return 0;
 596         }
 597
 598         ceph_calc_file_object_mapping(&ci->i_layout, off, map[0].len,
 599                                       &objno, &objoff, &xlen);
 600
 601         for (i = 0; i < ext_cnt; ++i) {
 602                 struct ceph_sparse_extent *ext = &map[i];
 603                 int pgsoff = ext->off - objoff;
 604                 int pgidx = pgsoff >> PAGE_SHIFT;
 605                 int fret;
 606
 607                 if ((ext->off | ext->len) & ~CEPH_FSCRYPT_BLOCK_MASK) {
 608                         pr_warn("%s: bad encrypted sparse extent idx %d off %llx len %llx\n",
 609                                 __func__, i, ext->off, ext->len);
 610                         return -EIO;
 611                 }
 612                 fret = ceph_fscrypt_decrypt_pages(inode, &page[pgidx],
 613                                                  off + pgsoff, ext->len);
 614                 dout("%s: [%d] 0x%llx~0x%llx fret %d\n", __func__, i,
 615                                 ext->off, ext->len, fret);
 616                 if (fret < 0) {
 617                         if (ret == 0)
 618                                 ret = fret;
 619                         break;
 620                 }
 621                 ret = pgsoff + fret;
 622         }
 623         dout("%s: ret %d\n", __func__, ret);
 624         return ret;
 625 }
 626
 627 /**
 628  * ceph_fscrypt_encrypt_pages - encrypt an array of pages
 629  * @inode: pointer to inode associated with these pages
 630  * @page: pointer to page array
 631  * @off: offset into the file that the data starts
 632  * @len: max length to encrypt
 633  * @gfp: gfp flags to use for allocation
 634  *
 635  * Decrypt an array of cleartext pages and return the amount of
 636  * data encrypted. Any data in the page prior to the start of the
 637  * first complete block in the read is ignored. Any incomplete
 638  * crypto blocks at the end of the array are ignored.
 639  *
 640  * Returns the length of the encrypted data or a negative errno.
 641  */
 642 int ceph_fscrypt_encrypt_pages(struct inode *inode, struct page **page, u64 off,
 643                                 int len, gfp_t gfp)
 644 {
 645         int i, num_blocks;
 646         u64 baseblk = off >> CEPH_FSCRYPT_BLOCK_SHIFT;
 647         int ret = 0;
 648
 649         /*
 650          * We can't deal with partial blocks on an encrypted file, so mask off
 651          * the last bit.
 652          */
 653         num_blocks = ceph_fscrypt_blocks(off, len & CEPH_FSCRYPT_BLOCK_MASK);
 654
 655         /* Encrypt each block */
 656         for (i = 0; i < num_blocks; ++i) {
 657                 int blkoff = i << CEPH_FSCRYPT_BLOCK_SHIFT;
 658                 int pgidx = blkoff >> PAGE_SHIFT;
 659                 unsigned int pgoffs = offset_in_page(blkoff);
 660                 int fret;
 661
 662                 fret = ceph_fscrypt_encrypt_block_inplace(inode, page[pgidx],
 663                                 CEPH_FSCRYPT_BLOCK_SIZE, pgoffs,
 664                                 baseblk + i, gfp);
 665                 if (fret < 0) {
 666                         if (ret == 0)
 667                                 ret = fret;
 668                         break;
 669                 }
 670                 ret += CEPH_FSCRYPT_BLOCK_SIZE;
 671         }
 672         return ret;
 673 }