[PATCH v3 09/15] hfsplus: implement get and verify block list header functionality

[PATCH v3 09/15] hfsplus: implement get and verify block list header functionality

[Vyacheslav Dubeyko]

From: Vyacheslav Dubeyko <slava@dubeyko.com>
Subject: [PATCH v3 09/15] hfsplus: implement get and verify block list header functionality

This patch implements functionality of reading of block list's
header from journal log and veryfing of it.

Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
CC: Al Viro <viro@zeniv.linux.org.uk>
CC: Christoph Hellwig <hch@infradead.org>
Tested-by: Hin-Tak Leung <htl10@users.sourceforge.net>
---
 fs/hfsplus/journal.c |  131 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)

diff --git a/fs/hfsplus/journal.c b/fs/hfsplus/journal.c
index be2d1ba..bfc4546 100644
--- a/fs/hfsplus/journal.c
+++ b/fs/hfsplus/journal.c
@@ -38,6 +38,11 @@
 	(be64_to_cpu(((struct hfsplus_journal *)(jnl))->jib->offset) >> \
 	 HFSPLUS_SB(sb)->alloc_blksz_shift)
 
+#define JOURNAL_OFF_TO_SEC(sb) \
+	(HFSPLUS_SB(sb)->blockoffset + \
+	 ((be64_to_cpu(HFSPLUS_SB(sb)->jnl->jib->offset) + \
+	   le64_to_cpu(HFSPLUS_SB(sb)->jnl->jh->start)) >> \
+	   HFSPLUS_SECTOR_SHIFT))
 #define BLOCK_TO_SEC(sb, blk) \
 	((sector_t)(blk) << \
 	 (HFSPLUS_SB(sb)->alloc_blksz_shift - HFSPLUS_SECTOR_SHIFT))
@@ -49,6 +54,18 @@
 #define JHDR_SIZE(jh) \
 	(le32_to_cpu(((struct hfsplus_journal_header *)(jh))->jhdr_size))
 
+#define TR_MAX_BLOCKS(blhdr) \
+	(le16_to_cpu(((struct hfsplus_blhdr *)(blhdr))->max_blocks))
+#define TR_BLOCKS(blhdr) \
+	(le16_to_cpu(((struct hfsplus_blhdr *)(blhdr))->num_blocks))
+#define TR_BYTES(blhdr) \
+	(le32_to_cpu(((struct hfsplus_blhdr *)(blhdr))->bytes_used))
+#define TR_SEQ_NUM(blhdr) \
+	(le32_to_cpu(((struct hfsplus_blhdr *)(blhdr))->binfo[0].block.seq_num))
+#define NEED_CHECK_CSUM(blhdr) \
+	(le32_to_cpu(((struct hfsplus_blhdr *)(blhdr))->flags) & \
+	 HFSPLUS_BLHDR_CHECK_CHECKSUMS)
+
 /*
  * struct hfsplus_blist_desc - descriptor of block list buffer
  * @start_sec: start sector of block list
@@ -302,15 +319,108 @@ failed_init:
 	return err;
 }
 
+static struct hfsplus_blhdr *hfsplus_get_blhdr(struct super_block *sb,
+						sector_t start_sector,
+						struct hfsplus_blist_desc *desc)
+{
+	struct hfsplus_blhdr *blhdr;
+	int err;
+
+	hfs_dbg(JREPLAY, "get block list header: start_sector %llu\n",
+		(unsigned long long)start_sector);
+
+	BUG_ON(!desc->blist_buf);
+
+	if (desc->start_sec == start_sector && desc->cur_sec == start_sector)
+		return &desc->blhdr;
+
+	err = hfsplus_submit_bio(sb, start_sector,
+				 desc->blist_buf, (void **)&blhdr, READA,
+				 &desc->available_bytes);
+	if (err) {
+		pr_err("unable to read block list header\n");
+		return NULL;
+	}
+
+	desc->start_sec = start_sector;
+	desc->cur_sec = start_sector;
+	memcpy((void *)&desc->blhdr, (const void *)blhdr, sizeof(*blhdr));
+	desc->binfo = &blhdr->binfo[0];
+
+	return &desc->blhdr;
+}
+
 static inline
 bool hfsplus_journal_empty(struct hfsplus_journal_header *jh)
 {
 	return TR_START(jh) == LAST_TR_END(jh);
 }
 
+static inline
+bool hfsplus_transaction_seq_num_valid(u32 prev_seq_num,
+					struct hfsplus_blhdr *blhdr)
+{
+	if (prev_seq_num != 0) {
+		u32 seq = TR_SEQ_NUM(blhdr);
+
+		if ((seq != 0) && (seq != prev_seq_num) &&
+		    (seq != (prev_seq_num + 1))) {
+			pr_err("transaction seq number %u is invalid\n",
+				TR_SEQ_NUM(blhdr));
+			return false;
+		}
+	}
+
+	return true;
+}
+
+static
+int hfsplus_verify_blhdr(u32 prev_seq_num, struct hfsplus_blhdr *blhdr)
+{
+	__le32 blhdr_checksum, cksum;
+
+	if (!hfsplus_transaction_seq_num_valid(prev_seq_num, blhdr))
+		return -EIO;
+
+	if (TR_BLOCKS(blhdr) == 0 || TR_BYTES(blhdr) == 0) {
+		pr_err("corrupted block list header\n");
+		hfs_dbg(JOURNAL, "num_blocks %u, max_blocks %u\n",
+			TR_BLOCKS(blhdr), TR_BYTES(blhdr));
+		return -EIO;
+	}
+
+	if (TR_BLOCKS(blhdr) > TR_MAX_BLOCKS(blhdr)) {
+		pr_err("corrupted block list header\n");
+		hfs_dbg(JOURNAL, "num_blocks %u, max_blocks %u\n",
+			TR_BLOCKS(blhdr), TR_MAX_BLOCKS(blhdr));
+		return -EIO;
+	}
+
+	if (!NEED_CHECK_CSUM(blhdr))
+		return 0; /* don't check checksums */
+
+	blhdr_checksum = blhdr->checksum;
+	blhdr->checksum = 0;
+
+	cksum = HFSPLUS_CALC_CHECKSUM((unsigned char *)blhdr, sizeof(*blhdr));
+	if (le32_to_cpu(cksum) != le32_to_cpu(blhdr_checksum)) {
+		blhdr->checksum = blhdr_checksum;
+		pr_err("corrupted block list header\n");
+		hfs_dbg(JOURNAL, "calculated CRC %#x, blhdr_checksum %#x\n",
+			cksum, be32_to_cpu(blhdr_checksum));
+		return -EIO;
+	}
+
+	blhdr->checksum = blhdr_checksum;
+	return 0;
+}
+
 static int hfsplus_replay_journal(struct super_block *sb)
 {
+	struct hfsplus_journal *jnl = HFSPLUS_SB(sb)->jnl;
+	struct hfsplus_journal_header *jh = jnl->jh;
 	struct hfsplus_blist_desc desc;
+	u32 last_seq_num = 0;
 	int err;
 
 	err = hfsplus_init_block_list_desc(sb, &desc);
@@ -319,9 +429,30 @@ static int hfsplus_replay_journal(struct super_block *sb)
 		return err;
 	}
 
+	/* Go through transactions */
+	while (!hfsplus_journal_empty(jh)) {
+		struct hfsplus_blhdr *blhdr;
+
+		blhdr = hfsplus_get_blhdr(sb, JOURNAL_OFF_TO_SEC(sb), &desc);
+		if (!blhdr) {
+			err = -EIO;
+			goto failed_journal_replay;
+		}
+
+		hfs_dbg(JREPLAY, "num_blocks: %u, bytes_used: %u\n",
+			TR_BLOCKS(blhdr), TR_BYTES(blhdr));
+
+		err = hfsplus_verify_blhdr(last_seq_num, blhdr);
+		if (err)
+			goto failed_journal_replay;
+
+		last_seq_num = TR_SEQ_NUM(blhdr);
+	}
+
 	/* TODO: implement */
 	return -EINVAL;
 
+failed_journal_replay:
 	hfsplus_deinit_block_list_desc(&desc);
 	return err;
 }
-- 
1.7.9.5