use-the-shash-api-correctly-for-crc32c

   1 ext4: use the shash api correctly for crc32c
   2
   3 From: "Darrick J. Wong" <darrick.wong@oracle.com>
   4
   5 Since we're using the crypto shash API, let's use the full API to set
   6 the seed and get the final checksum instead assuming the private data
   7 structure layout in crc32c.ko to which we're not privy.
   8
   9 Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
  10 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  11 ---
  12  fs/ext4/ext4.h       | 8 ++++++--
  13  include/linux/jbd2.h | 8 ++++++--
  14  2 files changed, 12 insertions(+), 4 deletions(-)
  15
  16 diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
  17 index 84255c0..a1e734d 100644
  18 --- a/fs/ext4/ext4.h
  19 +++ b/fs/ext4/ext4.h
  20 @@ -1742,18 +1742,22 @@ static inline u32 ext4_chksum(struct ext4_sb_info *sbi, u32 crc,
  21                 struct shash_desc shash;
  22                 char ctx[4];
  23         } desc;
  24 +       __le32 out_crc;
  25         int err;
  26
  27         BUG_ON(crypto_shash_descsize(sbi->s_chksum_driver)!=sizeof(desc.ctx));
  28
  29         desc.shash.tfm = sbi->s_chksum_driver;
  30         desc.shash.flags = 0;
  31 -       *(u32 *)desc.ctx = crc;
  32 +       out_crc = cpu_to_le32(crc);
  33 +       crypto_shash_setkey(desc.shash.tfm, (u8 *)&out_crc, sizeof(out_crc));
  34 +       crypto_shash_init(&desc.shash);
  35
  36         err = crypto_shash_update(&desc.shash, address, length);
  37         BUG_ON(err);
  38
  39 -       return *(u32 *)desc.ctx;
  40 +       crypto_shash_final(&desc.shash, (u8 *)&out_crc);
  41 +       return le32_to_cpu(~out_crc);
  42  }
  43
  44  #ifdef __KERNEL__
  45 diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
  46 index 704b9a5..ae365ca 100644
  47 --- a/include/linux/jbd2.h
  48 +++ b/include/linux/jbd2.h
  49 @@ -1374,6 +1374,7 @@ static inline u32 jbd2_chksum(journal_t *journal, u32 crc,
  50                 struct shash_desc shash;
  51                 char ctx[JBD_MAX_CHECKSUM_SIZE];
  52         } desc;
  53 +       __le32 out_crc;
  54         int err;
  55
  56         BUG_ON(crypto_shash_descsize(journal->j_chksum_driver) >
  57 @@ -1381,12 +1382,15 @@ static inline u32 jbd2_chksum(journal_t *journal, u32 crc,
  58
  59         desc.shash.tfm = journal->j_chksum_driver;
  60         desc.shash.flags = 0;
  61 -       *(u32 *)desc.ctx = crc;
  62 +       out_crc = cpu_to_le32(crc);
  63 +       crypto_shash_setkey(desc.shash.tfm, (u8 *)&out_crc, sizeof(out_crc));
  64 +       crypto_shash_init(&desc.shash);
  65
  66         err = crypto_shash_update(&desc.shash, address, length);
  67         BUG_ON(err);
  68
  69 -       return *(u32 *)desc.ctx;
  70 +       crypto_shash_final(&desc.shash, (u8 *)&out_crc);
  71 +       return le32_to_cpu(~out_crc);
  72  }
  73
  74  /* Return most recent uncommitted transaction */