This patch introduces to ext4 the ability to calculate and verify inode
checksums. This requires the use of a new ro compatibility flag and some
accompanying e2fsprogs patches to provide the relevant features in tune2fs and
e2fsck.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
fs/ext4/ext4.h | 4 ++--
fs/ext4/inode.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index f79ddac..e2361cc 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -609,7 +609,7 @@ struct ext4_inode {
__le16 l_i_file_acl_high;
__le16 l_i_uid_high; /* these 2 fields */
__le16 l_i_gid_high; /* were reserved2[0] */
- __u32 l_i_reserved2;
+ __le32 l_i_checksum; /* crc32c(uuid+inum+inode) */
} linux2;
struct {
__le16 h_i_reserved1; /* Obsoleted fragment number/size which are removed in ext4 */
@@ -727,7 +727,7 @@ do { \
#define i_gid_low i_gid
#define i_uid_high osd2.linux2.l_i_uid_high
#define i_gid_high osd2.linux2.l_i_gid_high
-#define i_reserved2 osd2.linux2.l_i_reserved2
+#define i_checksum osd2.linux2.l_i_checksum
#elif defined(__GNU__)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c4da98a..44a7f88 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -38,6 +38,7 @@
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/ratelimit.h>
+#include <linux/crc32c.h>
#include "ext4_jbd2.h"
#include "xattr.h"
@@ -49,6 +50,53 @@
#define MPAGE_DA_EXTENT_TAIL 0x01
+static __le32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ int offset = offsetof(struct ext4_inode, i_checksum);
+ __le32 inum = cpu_to_le32(inode->i_ino);
+ __u32 crc = 0;
+
+ if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
+ cpu_to_le32(EXT4_OS_LINUX))
+ return 0;
+ if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return 0;
+
+ crc = crc32c_le(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid));
+ crc = crc32c_le(crc, (__u8 *)&inum, sizeof(inum));
+ crc = crc32c_le(crc, (__u8 *)raw, offset);
+ offset += sizeof(raw->i_checksum); /* skip checksum */
+ crc = crc32c_le(crc, (__u8 *)raw + offset,
+ EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize -
+ offset);
+ return cpu_to_le32(crc);
+}
+
+static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw)
+{
+ if (EXT4_SB(inode->i_sb)->s_es->s_creator_os ==
+ cpu_to_le32(EXT4_OS_LINUX) &&
+ EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
+ (raw->i_checksum != ext4_inode_csum(inode, raw)))
+ return 0;
+ return 1;
+}
+
+static void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw)
+{
+ if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
+ cpu_to_le32(EXT4_OS_LINUX) ||
+ !EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return;
+
+ raw->i_checksum = ext4_inode_csum(inode, raw);
+}
+
static inline int ext4_begin_ordered_truncate(struct inode *inode,
loff_t new_size)
{
@@ -3410,6 +3458,15 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
if (ret < 0)
goto bad_inode;
raw_inode = ext4_raw_inode(&iloc);
+
+ if (!ext4_inode_csum_verify(inode, raw_inode)) {
+ EXT4_ERROR_INODE(inode, "checksum invalid (0x%x != 0x%x)",
+ le32_to_cpu(ext4_inode_csum(inode, raw_inode)),
+ le32_to_cpu(raw_inode->i_checksum));
+ ret = -EIO;
+ goto bad_inode;
+ }
+
inode->i_mode = le16_to_cpu(raw_inode->i_mode);
inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
@@ -3490,6 +3547,9 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
EXT4_INODE_SIZE(inode->i_sb)) {
+ EXT4_ERROR_INODE(inode, "bad extra_isize (%u != %u)",
+ EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize,
+ EXT4_INODE_SIZE(inode->i_sb));
ret = -EIO;
goto bad_inode;
}
@@ -3731,6 +3791,8 @@ static int ext4_do_update_inode(handle_t *handle,
raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
}
+ ext4_inode_csum_set(inode, raw_inode);
+
BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
rc = ext4_handle_dirty_metadata(handle, NULL, bh);
if (!err)
--
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