gate-checksum-calculations-on-crc-drive-presence

   1 jbd2: gate checksum calculations on crc driver presence, not sb flags
   2
   3 From: "Darrick J. Wong" <darrick.wong@oracle.com>
   4
   5 Change the journal's checksum functions to gate on whether or not the
   6 crc32c driver is loaded, and gate the loading on the superblock bits.
   7 This prevents a journal crash if someone loads a journal in no-csum
   8 mode and then randomizes the superblock, thus flipping on the feature
   9 bits.
  10
  11 Tested-By: Nikolay Borisov <kernel@kyup.com>
  12 Reported-by: Nikolay Borisov <kernel@kyup.com>
  13 Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
  14 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  15 ---
  16  fs/jbd2/journal.c    |    6 +++---
  17  include/linux/jbd2.h |   13 +++++++++----
  18  2 files changed, 12 insertions(+), 7 deletions(-)
  19
  20
  21 diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
  22 index 8270fe9..00f7dbd 100644
  23 --- a/fs/jbd2/journal.c
  24 +++ b/fs/jbd2/journal.c
  25 @@ -124,7 +124,7 @@ EXPORT_SYMBOL(__jbd2_debug);
  26  /* Checksumming functions */
  27  static int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
  28  {
  29 -       if (!jbd2_journal_has_csum_v2or3(j))
  30 +       if (!jbd2_journal_has_csum_v2or3_feature(j))
  31                 return 1;
  32
  33         return sb->s_checksum_type == JBD2_CRC32C_CHKSUM;
  34 @@ -1531,7 +1531,7 @@ static int journal_get_superblock(journal_t *journal)
  35                 goto out;
  36         }
  37
  38 -       if (jbd2_journal_has_csum_v2or3(journal) &&
  39 +       if (jbd2_journal_has_csum_v2or3_feature(journal) &&
  40             JBD2_HAS_COMPAT_FEATURE(journal, JBD2_FEATURE_COMPAT_CHECKSUM)) {
  41                 /* Can't have checksum v1 and v2 on at the same time! */
  42                 printk(KERN_ERR "JBD2: Can't enable checksumming v1 and v2/3 "
  43 @@ -1545,7 +1545,7 @@ static int journal_get_superblock(journal_t *journal)
  44         }
  45
  46         /* Load the checksum driver */
  47 -       if (jbd2_journal_has_csum_v2or3(journal)) {
  48 +       if (jbd2_journal_has_csum_v2or3_feature(journal)) {
  49                 journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
  50                 if (IS_ERR(journal->j_chksum_driver)) {
  51                         printk(KERN_ERR "JBD2: Cannot load crc32c driver.\n");
  52 diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
  53 index df07e78..6da6f89 100644
  54 --- a/include/linux/jbd2.h
  55 +++ b/include/linux/jbd2.h
  56 @@ -1338,13 +1338,18 @@ static inline int tid_geq(tid_t x, tid_t y)
  57  extern int jbd2_journal_blocks_per_page(struct inode *inode);
  58  extern size_t journal_tag_bytes(journal_t *journal);
  59
  60 +static inline bool jbd2_journal_has_csum_v2or3_feature(journal_t *j)
  61 +{
  62 +       return JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2) ||
  63 +              JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V3);
  64 +}
  65 +
  66  static inline int jbd2_journal_has_csum_v2or3(journal_t *journal)
  67  {
  68 -       if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2) ||
  69 -           JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V3))
  70 -               return 1;
  71 +       WARN_ON_ONCE(jbd2_journal_has_csum_v2or3_feature(journal) &&
  72 +                    journal->j_chksum_driver == NULL);
  73
  74 -       return 0;
  75 +       return journal->j_chksum_driver != NULL;
  76  }
  77
  78  /*
  79
  80