ext4: calculate and verify checksums for inode bitmaps

Compute and verify the checksum of the inode bitmap; the checkum is
stored in the block group descriptor.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

4 files changed, 135 insertions, 5 deletions

diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index fa3af81ac565..5813e7f2e2c6 100644
--- a/fs/ext4/bitmap.c
+++ b/fs/ext4/bitmap.c
@@ -29,3 +29,42 @@ unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars)
 
 #endif  /*  EXT4FS_DEBUG  */
 
+int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
+                                  struct ext4_group_desc *gdp,
+                                  struct buffer_head *bh, int sz)
+{
+        __u32 hi;
+        __u32 provided, calculated;
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                                        EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+                return 1;
+
+        provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
+        calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
+        if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
+                hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
+                provided |= (hi << 16);
+        } else
+                calculated &= 0xFFFF;
+
+        return provided == calculated;
+}
+
+void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
+                                struct ext4_group_desc *gdp,
+                                struct buffer_head *bh, int sz)
+{
+        __u32 csum;
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                                        EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+                return;
+
+        csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
+        gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
+        if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
+                gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
+}
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ca96401b4b81..7f0ff88f32ba 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -317,6 +317,13 @@ struct ext4_group_desc
         __u32   bg_reserved;
 };
 
+#define EXT4_BG_INODE_BITMAP_CSUM_HI_END        \
+        (offsetof(struct ext4_group_desc, bg_inode_bitmap_csum_hi) + \
+         sizeof(__le16))
+#define EXT4_BG_BLOCK_BITMAP_CSUM_HI_END        \
+        (offsetof(struct ext4_group_desc, bg_block_bitmap_csum_hi) + \
+         sizeof(__le16))
+
 /*
  * Structure of a flex block group info
  */
@@ -1844,6 +1851,12 @@ struct mmpd_data {
 
 /* bitmap.c */
 extern unsigned int ext4_count_free(struct buffer_head *, unsigned);
+void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
+                                struct ext4_group_desc *gdp,
+                                struct buffer_head *bh, int sz);
+int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
+                                  struct ext4_group_desc *gdp,
+                                  struct buffer_head *bh, int sz);
 
 /* balloc.c */
 extern unsigned int ext4_block_group(struct super_block *sb,
@@ -2094,6 +2107,13 @@ extern __le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 group,
 extern int ext4_group_desc_csum_verify(struct ext4_sb_info *sbi, __u32 group,
                                        struct ext4_group_desc *gdp);
 
+static inline int ext4_has_group_desc_csum(struct super_block *sb)
+{
+        return EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                                          EXT4_FEATURE_RO_COMPAT_GDT_CSUM |
+                                          EXT4_FEATURE_RO_COMPAT_METADATA_CSUM);
+}
+
 static inline ext4_fsblk_t ext4_blocks_count(struct ext4_super_block *es)
 {
         return ((ext4_fsblk_t)le32_to_cpu(es->s_blocks_count_hi) << 32) |
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 8207dfab2682..fb897ec183c8 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -82,12 +82,17 @@ static unsigned ext4_init_inode_bitmap(struct super_block *sb,
                 ext4_free_inodes_set(sb, gdp, 0);
                 ext4_itable_unused_set(sb, gdp, 0);
                 memset(bh->b_data, 0xff, sb->s_blocksize);
+                ext4_inode_bitmap_csum_set(sb, block_group, gdp, bh,
+                                           EXT4_INODES_PER_GROUP(sb) / 8);
                 return 0;
         }
 
         memset(bh->b_data, 0, (EXT4_INODES_PER_GROUP(sb) + 7) / 8);
         ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), sb->s_blocksize * 8,
                         bh->b_data);
+        ext4_inode_bitmap_csum_set(sb, block_group, gdp, bh,
+                                   EXT4_INODES_PER_GROUP(sb) / 8);
+        gdp->bg_checksum = ext4_group_desc_csum(sbi, block_group, gdp);
 
         return EXT4_INODES_PER_GROUP(sb);
 }
@@ -128,12 +133,12 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                 return NULL;
         }
         if (bitmap_uptodate(bh))
-                return bh;
+                goto verify;
 
         lock_buffer(bh);
         if (bitmap_uptodate(bh)) {
                 unlock_buffer(bh);
-                return bh;
+                goto verify;
         }
 
         ext4_lock_group(sb, block_group);
@@ -141,6 +146,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                 ext4_init_inode_bitmap(sb, bh, block_group, desc);
                 set_bitmap_uptodate(bh);
                 set_buffer_uptodate(bh);
+                set_buffer_verified(bh);
                 ext4_unlock_group(sb, block_group);
                 unlock_buffer(bh);
                 return bh;
@@ -154,7 +160,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                  */
                 set_bitmap_uptodate(bh);
                 unlock_buffer(bh);
-                return bh;
+                goto verify;
         }
         /*
          * submit the buffer_head for reading
@@ -171,6 +177,20 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                            block_group, bitmap_blk);
                 return NULL;
         }
+
+verify:
+        ext4_lock_group(sb, block_group);
+        if (!buffer_verified(bh) &&
+            !ext4_inode_bitmap_csum_verify(sb, block_group, desc, bh,
+                                           EXT4_INODES_PER_GROUP(sb) / 8)) {
+                ext4_unlock_group(sb, block_group);
+                put_bh(bh);
+                ext4_error(sb, "Corrupt inode bitmap - block_group = %u, "
+                           "inode_bitmap = %llu", block_group, bitmap_blk);
+                return NULL;
+        }
+        ext4_unlock_group(sb, block_group);
+        set_buffer_verified(bh);
         return bh;
 }
 
@@ -276,6 +296,8 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
                 ext4_used_dirs_set(sb, gdp, count);
                 percpu_counter_dec(&sbi->s_dirs_counter);
         }
+        ext4_inode_bitmap_csum_set(sb, block_group, gdp, bitmap_bh,
+                                   EXT4_INODES_PER_GROUP(sb) / 8);
         gdp->bg_checksum = ext4_group_desc_csum(sbi, block_group, gdp);
         ext4_unlock_group(sb, block_group);
 
@@ -751,7 +773,7 @@ got:
                 goto fail;
 
         /* Update the relevant bg descriptor fields */
-        if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
+        if (ext4_has_group_desc_csum(sb)) {
                 int free;
                 struct ext4_group_info *grp = ext4_get_group_info(sb, group);
 
@@ -782,7 +804,9 @@ got:
                         atomic_inc(&sbi->s_flex_groups[f].used_dirs);
                 }
         }
-        if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
+        if (ext4_has_group_desc_csum(sb)) {
+                ext4_inode_bitmap_csum_set(sb, group, gdp, inode_bitmap_bh,
+                                           EXT4_INODES_PER_GROUP(sb) / 8);
                 gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);
                 ext4_unlock_group(sb, group);
         }
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index e0374757a94b..7810cac241e1 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1069,6 +1069,47 @@ static int ext4_add_new_descs(handle_t *handle, struct super_block *sb,
         return err;
 }
 
+static struct buffer_head *ext4_get_bitmap(struct super_block *sb, __u64 block)
+{
+        struct buffer_head *bh = sb_getblk(sb, block);
+        if (!bh)
+                return NULL;
+
+        if (bitmap_uptodate(bh))
+                return bh;
+
+        lock_buffer(bh);
+        if (bh_submit_read(bh) < 0) {
+                unlock_buffer(bh);
+                brelse(bh);
+                return NULL;
+        }
+        unlock_buffer(bh);
+
+        return bh;
+}
+
+static int ext4_set_bitmap_checksums(struct super_block *sb,
+                                     ext4_group_t group,
+                                     struct ext4_group_desc *gdp,
+                                     struct ext4_new_group_data *group_data)
+{
+        struct buffer_head *bh;
+
+        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                                        EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+                return 0;
+
+        bh = ext4_get_bitmap(sb, group_data->inode_bitmap);
+        if (!bh)
+                return -EIO;
+        ext4_inode_bitmap_csum_set(sb, group, gdp, bh,
+                                   EXT4_INODES_PER_GROUP(sb) / 8);
+        brelse(bh);
+
+        return 0;
+}
+
 /*
  * ext4_setup_new_descs() will set up the group descriptor descriptors of a flex bg
  */
@@ -1101,6 +1142,12 @@ static int ext4_setup_new_descs(handle_t *handle, struct super_block *sb,
                 memset(gdp, 0, EXT4_DESC_SIZE(sb));
                 ext4_block_bitmap_set(sb, gdp, group_data->block_bitmap);
                 ext4_inode_bitmap_set(sb, gdp, group_data->inode_bitmap);
+                err = ext4_set_bitmap_checksums(sb, group, gdp, group_data);
+                if (err) {
+                        ext4_std_error(sb, err);
+                        break;
+                }
+
                 ext4_inode_table_set(sb, gdp, group_data->inode_table);
                 ext4_free_group_clusters_set(sb, gdp,
                                              EXT4_B2C(sbi, group_data->free_blocks_count));