dm: fix truncated status strings

commit fd7c092e upstream.

Avoid returning a truncated table or status string instead of setting
the DM_BUFFER_FULL_FLAG when the last target of a table fills the
buffer.

When processing a table or status request, the function retrieve_status
calls ti->type->status. If ti->type->status returns non-zero,
retrieve_status assumes that the buffer overflowed and sets
DM_BUFFER_FULL_FLAG.

However, targets don't return non-zero values from their status method
on overflow. Most targets returns always zero.

If a buffer overflow happens in a target that is not the last in the
table, it gets noticed during the next iteration of the loop in
retrieve_status; but if a buffer overflow happens in the last target, it
goes unnoticed and erroneously truncated data is returned.

In the current code, the targets behave in the following way:
* dm-crypt returns -ENOMEM if there is not enough space to store the
  key, but it returns 0 on all other overflows.
* dm-thin returns errors from the status method if a disk error happened.
  This is incorrect because retrieve_status doesn't check the error
  code, it assumes that all non-zero values mean buffer overflow.
* all the other targets always return 0.

This patch changes the ti->type->status function to return void (because
most targets don't use the return code). Overflow is detected in
retrieve_status: if the status method fills up the remaining space
completely, it is assumed that buffer overflow happened.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/md/dm-crypt.c

@@ -1262,20 +1262,6 @@ static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
 	return 0;
 }
 
-/*
- * Encode key into its hex representation
- */
-static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
-{
-	unsigned int i;
-
-	for (i = 0; i < size; i++) {
-		sprintf(hex, "%02x", *key);
-		hex += 2;
-		key++;
-	}
-}
-
 static void crypt_free_tfms(struct crypt_config *cc, int cpu)
 {
 	struct crypt_cpu *cpu_cc = per_cpu_ptr(cc->cpu, cpu);
@@ -1741,11 +1727,11 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
 	return DM_MAPIO_SUBMITTED;
 }
 
-static int crypt_status(struct dm_target *ti, status_type_t type,
+static void crypt_status(struct dm_target *ti, status_type_t type,
 			 char *result, unsigned int maxlen)
 {
 	struct crypt_config *cc = ti->private;
-	unsigned int sz = 0;
+	unsigned i, sz = 0;
 
 	switch (type) {
 	case STATUSTYPE_INFO:
@@ -1755,17 +1741,11 @@ static int crypt_status(struct dm_target *ti, status_type_t type,
 	case STATUSTYPE_TABLE:
 		DMEMIT("%s ", cc->cipher_string);
 
-		if (cc->key_size > 0) {
-			if ((maxlen - sz) < ((cc->key_size << 1) + 1))
-				return -ENOMEM;
-
-			crypt_encode_key(result + sz, cc->key, cc->key_size);
-			sz += cc->key_size << 1;
-		} else {
-			if (sz >= maxlen)
-				return -ENOMEM;
-			result[sz++] = '-';
-		}
+		if (cc->key_size > 0)
+			for (i = 0; i < cc->key_size; i++)
+				DMEMIT("%02x", cc->key[i]);
+		else
+			DMEMIT("-");
 
 		DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
 				cc->dev->name, (unsigned long long)cc->start);
@@ -1775,7 +1755,6 @@ static int crypt_status(struct dm_target *ti, status_type_t type,
 
 		break;
 	}
-	return 0;
 }
 
 static void crypt_postsuspend(struct dm_target *ti)

drivers/md/dm-delay.c

@@ -294,7 +294,7 @@ static int delay_map(struct dm_target *ti, struct bio *bio,
 	return delay_bio(dc, dc->read_delay, bio);
 }
 
-static int delay_status(struct dm_target *ti, status_type_t type,
+static void delay_status(struct dm_target *ti, status_type_t type,
 			 char *result, unsigned maxlen)
 {
 	struct delay_c *dc = ti->private;
@@ -315,8 +315,6 @@ static int delay_status(struct dm_target *ti, status_type_t type,
 			       dc->write_delay);
 		break;
 	}
-
-	return 0;
 }
 
 static int delay_iterate_devices(struct dm_target *ti,

drivers/md/dm-flakey.c

@@ -332,7 +332,7 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 	return error;
 }
 
-static int flakey_status(struct dm_target *ti, status_type_t type,
+static void flakey_status(struct dm_target *ti, status_type_t type,
 			  char *result, unsigned int maxlen)
 {
 	unsigned sz = 0;
@@ -363,7 +363,6 @@ static int flakey_status(struct dm_target *ti, status_type_t type,
 
 		break;
 	}
-	return 0;
 }
 
 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)

drivers/md/dm-ioctl.c

@@ -1066,6 +1066,7 @@ static void retrieve_status(struct dm_table *table,
 	num_targets = dm_table_get_num_targets(table);
 	for (i = 0; i < num_targets; i++) {
 		struct dm_target *ti = dm_table_get_target(table, i);
+		size_t l;
 
 		remaining = len - (outptr - outbuf);
 		if (remaining <= sizeof(struct dm_target_spec)) {
@@ -1089,15 +1090,18 @@ static void retrieve_status(struct dm_table *table,
 		}
 
 		/* Get the status/table string from the target driver */
-		if (ti->type->status) {
-			if (ti->type->status(ti, type, outptr, remaining)) {
+		if (ti->type->status)
+			ti->type->status(ti, type, outptr, remaining);
+		else
+			outptr[0] = '\0';
+
+		l = strlen(outptr) + 1;
+		if (l == remaining) {
 			param->flags |= DM_BUFFER_FULL_FLAG;
 			break;
 		}
-		} else
-			outptr[0] = '\0';
 
-		outptr += strlen(outptr) + 1;
+		outptr += l;
 		used = param->data_start + (outptr - outbuf);
 
 		outptr = align_ptr(outptr);

drivers/md/dm-linear.c

@@ -95,7 +95,7 @@ static int linear_map(struct dm_target *ti, struct bio *bio,
 	return DM_MAPIO_REMAPPED;
 }
 
-static int linear_status(struct dm_target *ti, status_type_t type,
+static void linear_status(struct dm_target *ti, status_type_t type,
 			  char *result, unsigned int maxlen)
 {
 	struct linear_c *lc = (struct linear_c *) ti->private;
@@ -110,7 +110,6 @@ static int linear_status(struct dm_target *ti, status_type_t type,
 				(unsigned long long)lc->start);
 		break;
 	}
-	return 0;
 }
 
 static int linear_ioctl(struct dm_target *ti, unsigned int cmd,

drivers/md/dm-mpath.c

@@ -1343,7 +1343,7 @@ static void multipath_resume(struct dm_target *ti)
  *     [priority selector-name num_ps_args [ps_args]*
  *      num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
  */
-static int multipath_status(struct dm_target *ti, status_type_t type,
+static void multipath_status(struct dm_target *ti, status_type_t type,
 			     char *result, unsigned int maxlen)
 {
 	int sz = 0;
@@ -1447,8 +1447,6 @@ static int multipath_status(struct dm_target *ti, status_type_t type,
 	}
 
 	spin_unlock_irqrestore(&m->lock, flags);
-
-	return 0;
 }
 
 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)

drivers/md/dm-raid.c

@@ -1067,7 +1067,7 @@ static int raid_map(struct dm_target *ti, struct bio *bio, union map_info *map_c
 	return DM_MAPIO_SUBMITTED;
 }
 
-static int raid_status(struct dm_target *ti, status_type_t type,
+static void raid_status(struct dm_target *ti, status_type_t type,
 			char *result, unsigned maxlen)
 {
 	struct raid_set *rs = ti->private;
@@ -1203,8 +1203,6 @@ static int raid_status(struct dm_target *ti, status_type_t type,
 				DMEMIT(" -");
 		}
 	}
-
-	return 0;
 }
 
 static int raid_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)

drivers/md/dm-raid1.c

@@ -1362,7 +1362,7 @@ static char device_status_char(struct mirror *m)
 }
 
 
-static int mirror_status(struct dm_target *ti, status_type_t type,
+static void mirror_status(struct dm_target *ti, status_type_t type,
 			  char *result, unsigned int maxlen)
 {
 	unsigned int m, sz = 0;
@@ -1398,8 +1398,6 @@ static int mirror_status(struct dm_target *ti, status_type_t type,
 		if (ms->features & DM_RAID1_HANDLE_ERRORS)
 			DMEMIT(" 1 handle_errors");
 	}
-
-	return 0;
 }
 
 static int mirror_iterate_devices(struct dm_target *ti,

drivers/md/dm-snap.c

@@ -1845,7 +1845,7 @@ static void snapshot_merge_resume(struct dm_target *ti)
 	start_merge(s);
 }
 
-static int snapshot_status(struct dm_target *ti, status_type_t type,
+static void snapshot_status(struct dm_target *ti, status_type_t type,
 			    char *result, unsigned int maxlen)
 {
 	unsigned sz = 0;
@@ -1892,8 +1892,6 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
 					  maxlen - sz);
 		break;
 	}
-
-	return 0;
 }
 
 static int snapshot_iterate_devices(struct dm_target *ti,
@@ -2148,7 +2146,7 @@ static void origin_resume(struct dm_target *ti)
 	ti->split_io = get_origin_minimum_chunksize(dev->bdev);
 }
 
-static int origin_status(struct dm_target *ti, status_type_t type, char *result,
+static void origin_status(struct dm_target *ti, status_type_t type, char *result,
 			  unsigned int maxlen)
 {
 	struct dm_dev *dev = ti->private;
@@ -2162,8 +2160,6 @@ static int origin_status(struct dm_target *ti, status_type_t type, char *result,
 		snprintf(result, maxlen, "%s", dev->name);
 		break;
 	}
-
-	return 0;
 }
 
 static int origin_merge(struct dm_target *ti, struct bvec_merge_data *bvm,

drivers/md/dm-stripe.c

@@ -302,7 +302,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio,
  *
  */
 
-static int stripe_status(struct dm_target *ti,
+static void stripe_status(struct dm_target *ti,
 			  status_type_t type, char *result, unsigned int maxlen)
 {
 	struct stripe_c *sc = (struct stripe_c *) ti->private;
@@ -330,7 +330,6 @@ static int stripe_status(struct dm_target *ti,
 			    (unsigned long long)sc->stripe[i].physical_start);
 		break;
 	}
-	return 0;
 }
 
 static int stripe_end_io(struct dm_target *ti, struct bio *bio,

drivers/md/dm-thin.c

@@ -2325,7 +2325,7 @@ static int pool_message(struct dm_target *ti, unsigned argc, char **argv)
  *    <transaction id> <used metadata sectors>/<total metadata sectors>
  *    <used data sectors>/<total data sectors> <held metadata root>
  */
-static int pool_status(struct dm_target *ti, status_type_t type,
+static void pool_status(struct dm_target *ti, status_type_t type,
 			char *result, unsigned maxlen)
 {
 	int r, count;
@@ -2343,32 +2343,41 @@ static int pool_status(struct dm_target *ti, status_type_t type,
 
 	switch (type) {
 	case STATUSTYPE_INFO:
-		r = dm_pool_get_metadata_transaction_id(pool->pmd,
-							&transaction_id);
-		if (r)
-			return r;
+		r = dm_pool_get_metadata_transaction_id(pool->pmd, &transaction_id);
+		if (r) {
+			DMERR("dm_pool_get_metadata_transaction_id returned %d", r);
+			goto err;
+		}
 
-		r = dm_pool_get_free_metadata_block_count(pool->pmd,
-							  &nr_free_blocks_metadata);
-		if (r)
-			return r;
+		r = dm_pool_get_free_metadata_block_count(pool->pmd, &nr_free_blocks_metadata);
+		if (r) {
+			DMERR("dm_pool_get_free_metadata_block_count returned %d", r);
+			goto err;
+		}
 
 		r = dm_pool_get_metadata_dev_size(pool->pmd, &nr_blocks_metadata);
-		if (r)
-			return r;
+		if (r) {
+			DMERR("dm_pool_get_metadata_dev_size returned %d", r);
+			goto err;
+		}
 
-		r = dm_pool_get_free_block_count(pool->pmd,
-						 &nr_free_blocks_data);
-		if (r)
-			return r;
+		r = dm_pool_get_free_block_count(pool->pmd, &nr_free_blocks_data);
+		if (r) {
+			DMERR("dm_pool_get_free_block_count returned %d", r);
+			goto err;
+		}
 
 		r = dm_pool_get_data_dev_size(pool->pmd, &nr_blocks_data);
-		if (r)
-			return r;
+		if (r) {
+			DMERR("dm_pool_get_data_dev_size returned %d", r);
+			goto err;
+		}
 
 		r = dm_pool_get_held_metadata_root(pool->pmd, &held_root);
-		if (r)
-			return r;
+		if (r) {
+			DMERR("dm_pool_get_metadata_snap returned %d", r);
+			goto err;
+		}
 
 		DMEMIT("%llu %llu/%llu %llu/%llu ",
 		       (unsigned long long)transaction_id,
@@ -2406,8 +2415,10 @@ static int pool_status(struct dm_target *ti, status_type_t type,
 
 		break;
 	}
+	return;
 
-	return 0;
+err:
+	DMEMIT("Error");
 }
 
 static int pool_iterate_devices(struct dm_target *ti,
@@ -2659,7 +2670,7 @@ static void thin_postsuspend(struct dm_target *ti)
 /*
  * <nr mapped sectors> <highest mapped sector>
  */
-static int thin_status(struct dm_target *ti, status_type_t type,
+static void thin_status(struct dm_target *ti, status_type_t type,
 			char *result, unsigned maxlen)
 {
 	int r;
@@ -2674,12 +2685,16 @@ static int thin_status(struct dm_target *ti, status_type_t type,
 		switch (type) {
 		case STATUSTYPE_INFO:
 			r = dm_thin_get_mapped_count(tc->td, &mapped);
-			if (r)
-				return r;
+			if (r) {
+				DMERR("dm_thin_get_mapped_count returned %d", r);
+				goto err;
+			}
 
 			r = dm_thin_get_highest_mapped_block(tc->td, &highest);
-			if (r < 0)
-				return r;
+			if (r < 0) {
+				DMERR("dm_thin_get_highest_mapped_block returned %d", r);
+				goto err;
+			}
 
 			DMEMIT("%llu ", mapped * tc->pool->sectors_per_block);
 			if (r)
@@ -2699,7 +2714,10 @@ static int thin_status(struct dm_target *ti, status_type_t type,
 		}
 	}
 
-	return 0;
+	return;
+
+err:
+	DMEMIT("Error");
 }
 
 static int thin_iterate_devices(struct dm_target *ti,

drivers/md/dm-verity.c

@@ -514,7 +514,7 @@ static int verity_map(struct dm_target *ti, struct bio *bio,
 /*
  * Status: V (valid) or C (corruption found)
  */
-static int verity_status(struct dm_target *ti, status_type_t type,
+static void verity_status(struct dm_target *ti, status_type_t type,
 			  char *result, unsigned maxlen)
 {
 	struct dm_verity *v = ti->private;
@@ -546,8 +546,6 @@ static int verity_status(struct dm_target *ti, status_type_t type,
 				DMEMIT("%02x", v->salt[x]);
 		break;
 	}
-
-	return 0;
 }
 
 static int verity_ioctl(struct dm_target *ti, unsigned cmd,

include/linux/device-mapper.h

@@ -72,7 +72,7 @@ typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
 typedef int (*dm_preresume_fn) (struct dm_target *ti);
 typedef void (*dm_resume_fn) (struct dm_target *ti);
 
-typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
+typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
 			      char *result, unsigned int maxlen);
 
 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);