libext2fs: add inode checksum support

This patch adds the ability for the libext2fs functions to read and
write the inode checksum.

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

6 files changed, 131 insertions, 10 deletions

diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
index aefa762b..fb9d0c09 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -30,6 +30,88 @@
 #define STATIC static
 #endif
 
+static errcode_t ext2fs_inode_csum(ext2_filsys fs, ext2_ino_t inum,
+			       struct ext2_inode_large *inode,
+			       __u32 *crc, int has_hi)
+{
+	__u32 gen;
+	struct ext2_inode_large *desc = inode;
+	size_t size = fs->super->s_inode_size;
+	__u16 old_lo;
+	__u16 old_hi = 0;
+
+	old_lo = inode->i_checksum_lo;
+	inode->i_checksum_lo = 0;
+	if (has_hi) {
+		old_hi = inode->i_checksum_hi;
+		inode->i_checksum_hi = 0;
+	}
+
+	inum = ext2fs_cpu_to_le32(inum);
+	gen = inode->i_generation;
+	*crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
+				sizeof(inum));
+	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
+	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)desc, size);
+
+	inode->i_checksum_lo = old_lo;
+	if (has_hi)
+		inode->i_checksum_hi = old_hi;
+	return 0;
+}
+
+int ext2fs_inode_csum_verify(ext2_filsys fs, ext2_ino_t inum,
+			     struct ext2_inode_large *inode)
+{
+	errcode_t retval;
+	__u32 provided, calculated;
+	int has_hi;
+
+	if (fs->super->s_creator_os != EXT2_OS_LINUX ||
+	    !EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return 1;
+
+	has_hi = (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE &&
+		  inode->i_extra_isize >= EXT4_INODE_CSUM_HI_EXTRA_END);
+
+	provided = ext2fs_le16_to_cpu(inode->i_checksum_lo);
+	retval = ext2fs_inode_csum(fs, inum, inode, &calculated, has_hi);
+	if (retval)
+		return 0;
+	if (has_hi) {
+		__u32 hi = ext2fs_le16_to_cpu(inode->i_checksum_hi);
+		provided |= hi << 16;
+	} else
+		calculated &= 0xFFFF;
+
+	return provided == calculated;
+}
+
+errcode_t ext2fs_inode_csum_set(ext2_filsys fs, ext2_ino_t inum,
+			   struct ext2_inode_large *inode)
+{
+	errcode_t retval;
+	__u32 crc;
+	int has_hi;
+
+	if (fs->super->s_creator_os != EXT2_OS_LINUX ||
+	    !EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return 0;
+
+	has_hi = (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE &&
+		  inode->i_extra_isize >= EXT4_INODE_CSUM_HI_EXTRA_END);
+
+	retval = ext2fs_inode_csum(fs, inum, inode, &crc, has_hi);
+	if (retval)
+		return retval;
+	inode->i_checksum_lo = ext2fs_cpu_to_le16(crc & 0xFFFF);
+	if (has_hi)
+		inode->i_checksum_hi = ext2fs_cpu_to_le16(crc >> 16);
+	return 0;
+}
+
 __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
 {
 	__u16 crc = 0;
diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
index 59871853..0b490f1a 100644
--- a/lib/ext2fs/ext2_err.et.in
+++ b/lib/ext2fs/ext2_err.et.in
@@ -446,4 +446,7 @@ ec	EXT2_ET_MMP_OPEN_DIRECT,
 ec	EXT2_ET_BAD_DESC_SIZE,
 	"Block group descriptor size incorrect"
 
+ec	EXT2_ET_INODE_CSUM_INVALID,
+	"Inode checksum does not match inode"
+
 	end
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index 39cc534f..8b70f167 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -461,6 +461,10 @@ struct ext2_inode_large {
 	__u32	i_version_hi;	/* high 32 bits for 64-bit version */
 };
 
+#define EXT4_INODE_CSUM_HI_EXTRA_END	\
+	(offsetof(struct ext2_inode_large, i_checksum_hi) + sizeof(__u16) - \
+	 EXT2_GOOD_OLD_INODE_SIZE)
+
 #define i_dir_acl	i_size_high
 
 #if defined(__KERNEL__) || defined(__linux__)
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index ed8f0bd0..17cd81b7 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -939,6 +939,10 @@ extern __u32 ext2fs_crc32c_be(__u32 crc, unsigned char const *p, size_t len);
 extern __u32 ext2fs_crc32c_le(__u32 crc, unsigned char const *p, size_t len);
 
 /* csum.c */
+extern errcode_t ext2fs_inode_csum_set(ext2_filsys fs, ext2_ino_t inum,
+				       struct ext2_inode_large *inode);
+extern int ext2fs_inode_csum_verify(ext2_filsys fs, ext2_ino_t inum,
+				    struct ext2_inode_large *inode);
 extern void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group);
 extern int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group);
 extern errcode_t ext2fs_set_gdt_csum(ext2_filsys fs);
diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c
index 9ddaf59d..5da57206 100644
--- a/lib/ext2fs/inode.c
+++ b/lib/ext2fs/inode.c
@@ -417,7 +417,7 @@ errcode_t ext2fs_get_next_inode_full(ext2_inode_scan scan, ext2_ino_t *ino,
 	errcode_t	retval;
 	int		extra_bytes = 0;
 	const int	length = EXT2_INODE_SIZE(scan->fs->super);
-	struct ext2_inode	*iptr = inode;
+	struct ext2_inode_large	*iptr = (struct ext2_inode_large *)inode;
 
 	EXT2_CHECK_MAGIC(scan, EXT2_ET_MAGIC_INODE_SCAN);
 
@@ -493,6 +493,12 @@ errcode_t ext2fs_get_next_inode_full(ext2_inode_scan scan, ext2_ino_t *ino,
 		scan->ptr += scan->inode_size - extra_bytes;
 		scan->bytes_left -= scan->inode_size - extra_bytes;
 
+		/* Verify the inode checksum. */
+		if (!(scan->fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
+		    !ext2fs_inode_csum_verify(scan->fs, scan->current_inode + 1,
+				(struct ext2_inode_large *)scan->temp_buffer))
+			retval = EXT2_ET_INODE_CSUM_INVALID;
+
 #ifdef WORDS_BIGENDIAN
 		memset(iptr, 0, length);
 		ext2fs_swap_inode_full(scan->fs,
@@ -506,6 +512,12 @@ errcode_t ext2fs_get_next_inode_full(ext2_inode_scan scan, ext2_ino_t *ino,
 			retval = EXT2_ET_BAD_BLOCK_IN_INODE_TABLE;
 		scan->scan_flags &= ~EXT2_SF_BAD_EXTRA_BYTES;
 	} else {
+		/* Verify the inode checksum. */
+		if (!(scan->fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
+		    !ext2fs_inode_csum_verify(scan->fs, scan->current_inode + 1,
+				(struct ext2_inode_large *)scan->ptr))
+			retval = EXT2_ET_INODE_CSUM_INVALID;
+
 #ifdef WORDS_BIGENDIAN
 		memset(iptr, 0, length);
 		ext2fs_swap_inode_full(scan->fs,
@@ -524,7 +536,7 @@ errcode_t ext2fs_get_next_inode_full(ext2_inode_scan scan, ext2_ino_t *ino,
 	scan->inodes_left--;
 	scan->current_inode++;
 	*ino = scan->current_inode;
-	if (inode != iptr) {
+	if (iptr != (struct ext2_inode_large *)inode) {
 		memcpy(inode, iptr, bufsize);
 		ext2fs_free_mem(&iptr);
 	}
@@ -551,7 +563,7 @@ errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,
 	int		clen, i, inodes_per_block;
 	io_channel	io;
 	int		length = EXT2_INODE_SIZE(fs->super);
-	struct ext2_inode	*iptr;
+	struct ext2_inode_large	*iptr;
 	int		cache_slot;
 
 	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
@@ -600,7 +612,7 @@ errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,
 	offset &= (EXT2_BLOCK_SIZE(fs->super) - 1);
 
 	cache_slot = (fs->icache->cache_last + 1) % fs->icache->cache_size;
-	iptr = fs->icache->cache[cache_slot].inode;
+	iptr = (struct ext2_inode_large *)fs->icache->cache[cache_slot].inode;
 
 	ptr = (char *) iptr;
 	while (length) {
@@ -626,6 +638,11 @@ errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,
 	}
 	length = EXT2_INODE_SIZE(fs->super);
 
+	/* Verify the inode checksum. */
+	if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
+	    !ext2fs_inode_csum_verify(fs, ino, iptr))
+		return EXT2_ET_INODE_CSUM_INVALID;
+
 #ifdef WORDS_BIGENDIAN
 	ext2fs_swap_inode_full(fs, (struct ext2_inode_large *) iptr,
 			       (struct ext2_inode_large *) iptr,
@@ -674,12 +691,17 @@ errcode_t ext2fs_write_inode_full(ext2_filsys fs, ext2_ino_t ino,
 	retval = ext2fs_get_mem(length, &w_inode);
 	if (retval)
 		return retval;
-	if (bufsize < length)
+
+	if (bufsize < length) {
+		int old_flags = fs->flags;
+		fs->flags |= EXT2_FLAG_IGNORE_CSUM_ERRORS;
 		retval = ext2fs_read_inode_full(fs, ino,
 						(struct ext2_inode *)w_inode,
 						length);
-	if (retval)
-		goto errout;
+		fs->flags = old_flags;
+		if (retval)
+			goto errout;
+	}
 
 	/* Check to see if the inode cache needs to be updated */
 	if (fs->icache) {
@@ -706,6 +728,10 @@ errcode_t ext2fs_write_inode_full(ext2_filsys fs, ext2_ino_t ino,
 	ext2fs_swap_inode_full(fs, w_inode, w_inode, 1, length);
 #endif
 
+	retval = ext2fs_inode_csum_set(fs, ino, w_inode);
+	if (retval)
+		goto errout;
+
 	group = (ino - 1) / EXT2_INODES_PER_GROUP(fs->super);
 	offset = ((ino - 1) % EXT2_INODES_PER_GROUP(fs->super)) *
 		EXT2_INODE_SIZE(fs->super);
diff --git a/lib/ext2fs/mkdir.c b/lib/ext2fs/mkdir.c
index b12bf2dd..861ddabb 100644
--- a/lib/ext2fs/mkdir.c
+++ b/lib/ext2fs/mkdir.c
@@ -93,12 +93,14 @@ errcode_t ext2fs_mkdir(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t inum,
 	inode.i_size = fs->blocksize;
 
 	/*
-	 * Write out the inode and inode data block
+	 * Write out the inode and inode data block.  The inode generation
+	 * number is assigned by write_new_inode, which means that the call
+	 * to write_dir_block must come after that.
 	 */
-	retval = ext2fs_write_dir_block(fs, blk, block);
+	retval = ext2fs_write_new_inode(fs, ino, &inode);
 	if (retval)
 		goto cleanup;
-	retval = ext2fs_write_new_inode(fs, ino, &inode);
+	retval = ext2fs_write_dir_block(fs, blk, block);
 	if (retval)
 		goto cleanup;