From: Stefan Metzmacher <metze@samba.org>
Date: Thu, 9 Sep 2010 13:45:51 +0000 (+0200)
Subject: lib/tdb: maintain reference hashes with the hash function that's used at create time
X-Git-Url: http://git.samba.org/?a=commitdiff_plain;ds=sidebyside;h=b2b69f1281c36c2fa67407856e443260b7868f4e;p=metze%2Fsamba%2Fwip.git

lib/tdb: maintain reference hashes with the hash function that's used at create time

If the hashes are available and the current hash function can't verify
them, we reject the open.

metze
---

diff --git a/lib/tdb/common/open.c b/lib/tdb/common/open.c
index 49b8e85f1264..ff0fd376017b 100644
--- a/lib/tdb/common/open.c
+++ b/lib/tdb/common/open.c
@@ -52,6 +52,7 @@ static int tdb_new_database(struct tdb_context *tdb, int hash_size)
 	size_t size;
 	int ret = -1;
 	ssize_t written;
+	TDB_DATA hash_key;
 
 	/* We make it up in memory, then write it out if not internal */
 	size = sizeof(struct tdb_header) + (hash_size+1)*sizeof(tdb_off_t);
@@ -61,6 +62,15 @@ static int tdb_new_database(struct tdb_context *tdb, int hash_size)
 	/* Fill in the header */
 	newdb->version = TDB_VERSION;
 	newdb->hash_size = hash_size;
+
+	hash_key.dptr = discard_const_p(uint8_t, TDB_MAGIC_FOOD);
+	hash_key.dsize = sizeof(TDB_MAGIC_FOOD);
+	newdb->magic_food_hash = tdb->hash_fn(&hash_key);
+
+	hash_key.dptr = discard_const_p(uint8_t, TDB_MAGIC_HASH_VERIFY_KEY);
+	hash_key.dsize = sizeof(TDB_MAGIC_HASH_VERIFY_KEY);
+	newdb->verify_key_hash = tdb->hash_fn(&hash_key);
+
 	if (tdb->flags & TDB_INTERNAL) {
 		tdb->map_size = size;
 		tdb->map_ptr = (char *)newdb;
@@ -153,6 +163,10 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
 	unsigned char *vp;
 	uint32_t vertest;
 	unsigned v;
+	TDB_DATA hash_key;
+	uint32_t magic_food_hash;
+	uint32_t verify_key_hash;
+	const char *hash_alg;
 
 	if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) {
 		/* Can't log this */
@@ -171,7 +185,14 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
 		tdb->log.log_fn = null_log_fn;
 		tdb->log.log_private = NULL;
 	}
-	tdb->hash_fn = hash_fn ? hash_fn : default_tdb_hash;
+
+	if (hash_fn) {
+		tdb->hash_fn = hash_fn;
+		hash_alg = "user_defined";
+	} else {
+		tdb->hash_fn = default_tdb_hash;
+		hash_alg = "default";
+	}
 
 	/* cache the page size */
 	tdb->page_size = getpagesize();
@@ -270,6 +291,35 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
 		goto fail;
 	}
 
+	hash_key.dptr = discard_const_p(uint8_t, TDB_MAGIC_FOOD);
+	hash_key.dsize = sizeof(TDB_MAGIC_FOOD);
+	magic_food_hash = tdb->hash_fn(&hash_key);
+
+	hash_key.dptr = discard_const_p(uint8_t, TDB_MAGIC_HASH_VERIFY_KEY);
+	hash_key.dsize = sizeof(TDB_MAGIC_HASH_VERIFY_KEY);
+	verify_key_hash = tdb->hash_fn(&hash_key);
+
+	if ((tdb->header.magic_food_hash == 0) &&
+	    (tdb->header.verify_key_hash == 0)) {
+		/* older TDB without magic hash references */
+	} else if ((tdb->header.magic_food_hash != magic_food_hash) ||
+		   (tdb->header.verify_key_hash != verify_key_hash)) {
+		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: %s "
+			 "was created with a different hash function current[%s]"
+			 "magic_food_hash[0x%08X %s 0x%08X] "
+			 "verify_key_hash[0x%08X %s 0x%08X]\n",
+			 name,
+			 hash_alg,
+			 tdb->header.magic_food_hash,
+			 (tdb->header.magic_food_hash == magic_food_hash)?"==":"!=",
+			 magic_food_hash,
+			 tdb->header.verify_key_hash,
+			 (tdb->header.verify_key_hash == verify_key_hash)?"==":"!=",
+			 verify_key_hash));
+		errno = EINVAL;
+		goto fail;
+	}
+
 	/* Is it already in the open list?  If so, fail. */
 	if (tdb_already_open(st.st_dev, st.st_ino)) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
diff --git a/lib/tdb/common/tdb_private.h b/lib/tdb/common/tdb_private.h
index 562b813ff115..226ace279c50 100644
--- a/lib/tdb/common/tdb_private.h
+++ b/lib/tdb/common/tdb_private.h
@@ -48,6 +48,7 @@ typedef uint32_t tdb_off_t;
 #define TDB_FREE_MAGIC (~TDB_MAGIC)
 #define TDB_DEAD_MAGIC (0xFEE1DEAD)
 #define TDB_RECOVERY_MAGIC (0xf53bc0e7U)
+#define TDB_MAGIC_HASH_VERIFY_KEY "!TDB_MAGIC_HASH_VERIFY_KEY!"
 #define TDB_ALIGNMENT 4
 #define DEFAULT_HASH_SIZE 131
 #define FREELIST_TOP (sizeof(struct tdb_header))
@@ -114,7 +115,9 @@ struct tdb_header {
 	tdb_off_t rwlocks; /* obsolete - kept to detect old formats */
 	tdb_off_t recovery_start; /* offset of transaction recovery region */
 	tdb_off_t sequence_number; /* used when TDB_SEQNUM is set */
-	tdb_off_t reserved[29];
+	uint32_t magic_food_hash;
+	uint32_t verify_key_hash;
+	tdb_off_t reserved[27];
 };
 
 struct tdb_lock_type {