fs/ubifs/crypto.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "ubifs.h"
   3
   4 static 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
  10 static 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
  22 static bool ubifs_crypt_empty_dir(struct inode *inode)
  23 {
  24         return ubifs_check_dir_empty(inode) == 0;
  25 }
  26
  27 static unsigned int ubifs_crypt_max_namelen(struct inode *inode)
  28 {
  29         if (S_ISLNK(inode->i_mode))
  30                 return UBIFS_MAX_INO_DATA;
  31         else
  32                 return UBIFS_MAX_NLEN;
  33 }
  34
  35 int ubifs_encrypt(const struct inode *inode, struct ubifs_data_node *dn,
  36                   unsigned int in_len, unsigned int *out_len, int block)
  37 {
  38         struct ubifs_info *c = inode->i_sb->s_fs_info;
  39         void *p = &dn->data;
  40         struct page *ret;
  41         unsigned int pad_len = round_up(in_len, UBIFS_CIPHER_BLOCK_SIZE);
  42
  43         ubifs_assert(pad_len <= *out_len);
  44         dn->compr_size = cpu_to_le16(in_len);
  45
  46         /* pad to full block cipher length */
  47         if (pad_len != in_len)
  48                 memset(p + in_len, 0, pad_len - in_len);
  49
  50         ret = fscrypt_encrypt_page(inode, virt_to_page(&dn->data), pad_len,
  51                         offset_in_page(&dn->data), block, GFP_NOFS);
  52         if (IS_ERR(ret)) {
  53                 ubifs_err(c, "fscrypt_encrypt_page failed: %ld", PTR_ERR(ret));
  54                 return PTR_ERR(ret);
  55         }
  56         *out_len = pad_len;
  57
  58         return 0;
  59 }
  60
  61 int ubifs_decrypt(const struct inode *inode, struct ubifs_data_node *dn,
  62                   unsigned int *out_len, int block)
  63 {
  64         struct ubifs_info *c = inode->i_sb->s_fs_info;
  65         int err;
  66         unsigned int clen = le16_to_cpu(dn->compr_size);
  67         unsigned int dlen = *out_len;
  68
  69         if (clen <= 0 || clen > UBIFS_BLOCK_SIZE || clen > dlen) {
  70                 ubifs_err(c, "bad compr_size: %i", clen);
  71                 return -EINVAL;
  72         }
  73
  74         ubifs_assert(dlen <= UBIFS_BLOCK_SIZE);
  75         err = fscrypt_decrypt_page(inode, virt_to_page(&dn->data), dlen,
  76                         offset_in_page(&dn->data), block);
  77         if (err) {
  78                 ubifs_err(c, "fscrypt_decrypt_page failed: %i", err);
  79                 return err;
  80         }
  81         *out_len = clen;
  82
  83         return 0;
  84 }
  85
  86 const struct fscrypt_operations ubifs_crypt_operations = {
  87         .flags                  = FS_CFLG_OWN_PAGES,
  88         .key_prefix             = "ubifs:",
  89         .get_context            = ubifs_crypt_get_context,
  90         .set_context            = ubifs_crypt_set_context,
  91         .is_encrypted           = __ubifs_crypt_is_encrypted,
  92         .empty_dir              = ubifs_crypt_empty_dir,
  93         .max_namelen            = ubifs_crypt_max_namelen,
  94 };