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Subject[PATCH 07/23] ext4: Calculate and verify checksums for inode bitmaps
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Date
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>
---
fs/ext4/bitmap.c | 39 +++++++++++++++++++++++++++++++++++++++
fs/ext4/ext4.h | 13 +++++++++++++
fs/ext4/ialloc.c | 30 +++++++++++++++++++++++++++---
fs/ext4/resize.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 126 insertions(+), 3 deletions(-)


diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index fa3af81..0ae4a01 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 e2bd9b9..16b6bb1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -308,6 +308,13 @@ 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
*/
@@ -1832,6 +1839,12 @@ 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,
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 0ee26c4..e87a49a 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);
}
@@ -118,12 +123,12 @@ 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);
@@ -131,6 +136,7 @@ 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;
@@ -144,7 +150,7 @@ 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 read. We can
@@ -161,6 +167,20 @@ 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;
}

@@ -265,6 +285,8 @@ 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);

@@ -673,6 +695,8 @@ static int ext4_claim_inode(struct super_block *sb,
atomic_inc(&sbi->s_flex_groups[f].used_dirs);
}
}
+ 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);
err_ret:
ext4_unlock_group(sb, group);
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 20c0a54..0953f07 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));


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