linux/fs/ubifs/crypto.c
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   1// SPDX-License-Identifier: GPL-2.0
   2#include "ubifs.h"
   3
   4static int ubifs_crypt_get_context(struct inode *inode, void *ctx, size_t len)
   5{
   6        return ubifs_xattr_get(inode, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT,
   7                               ctx, len);
   8}
   9
  10static int ubifs_crypt_set_context(struct inode *inode, const void *ctx,
  11                                   size_t len, void *fs_data)
  12{
  13        /*
  14         * Creating an encryption context is done unlocked since we
  15         * operate on a new inode which is not visible to other users
  16         * at this point. So, no need to check whether inode is locked.
  17         */
  18        return ubifs_xattr_set(inode, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT,
  19                               ctx, len, 0, false);
  20}
  21
  22static bool ubifs_crypt_empty_dir(struct inode *inode)
  23{
  24        return ubifs_check_dir_empty(inode) == 0;
  25}
  26
  27int ubifs_encrypt(const struct inode *inode, struct ubifs_data_node *dn,
  28                  unsigned int in_len, unsigned int *out_len, int block)
  29{
  30        struct ubifs_info *c = inode->i_sb->s_fs_info;
  31        void *p = &dn->data;
  32        unsigned int pad_len = round_up(in_len, UBIFS_CIPHER_BLOCK_SIZE);
  33        int err;
  34
  35        ubifs_assert(c, pad_len <= *out_len);
  36        dn->compr_size = cpu_to_le16(in_len);
  37
  38        /* pad to full block cipher length */
  39        if (pad_len != in_len)
  40                memset(p + in_len, 0, pad_len - in_len);
  41
  42        err = fscrypt_encrypt_block_inplace(inode, virt_to_page(p), pad_len,
  43                                            offset_in_page(p), block, GFP_NOFS);
  44        if (err) {
  45                ubifs_err(c, "fscrypt_encrypt_block_inplace() failed: %d", err);
  46                return err;
  47        }
  48        *out_len = pad_len;
  49
  50        return 0;
  51}
  52
  53int ubifs_decrypt(const struct inode *inode, struct ubifs_data_node *dn,
  54                  unsigned int *out_len, int block)
  55{
  56        struct ubifs_info *c = inode->i_sb->s_fs_info;
  57        int err;
  58        unsigned int clen = le16_to_cpu(dn->compr_size);
  59        unsigned int dlen = *out_len;
  60
  61        if (clen <= 0 || clen > UBIFS_BLOCK_SIZE || clen > dlen) {
  62                ubifs_err(c, "bad compr_size: %i", clen);
  63                return -EINVAL;
  64        }
  65
  66        ubifs_assert(c, dlen <= UBIFS_BLOCK_SIZE);
  67        err = fscrypt_decrypt_block_inplace(inode, virt_to_page(&dn->data),
  68                                            dlen, offset_in_page(&dn->data),
  69                                            block);
  70        if (err) {
  71                ubifs_err(c, "fscrypt_decrypt_block_inplace() failed: %d", err);
  72                return err;
  73        }
  74        *out_len = clen;
  75
  76        return 0;
  77}
  78
  79const struct fscrypt_operations ubifs_crypt_operations = {
  80        .flags                  = FS_CFLG_OWN_PAGES,
  81        .key_prefix             = "ubifs:",
  82        .get_context            = ubifs_crypt_get_context,
  83        .set_context            = ubifs_crypt_set_context,
  84        .empty_dir              = ubifs_crypt_empty_dir,
  85        .max_namelen            = UBIFS_MAX_NLEN,
  86};
  87
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