[PATCH 3.4 31/32] dm: fix truncated status strings

Greg Kroah-Hartman
2013-12-06T21:57:25Z

From: Mikulas Patocka <mpatocka@redhat.com>

commit fd7c092e711ebab55b2688d3859d95dfd0301f73 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 | 37 ++++----------------
drivers/md/dm-delay.c | 6 +--
drivers/md/dm-flakey.c | 5 +-
drivers/md/dm-ioctl.c | 18 ++++++---
drivers/md/dm-linear.c | 5 +-
drivers/md/dm-mpath.c | 6 +--
drivers/md/dm-raid.c | 6 +--
drivers/md/dm-raid1.c | 6 +--
drivers/md/dm-snap.c | 12 ++----
drivers/md/dm-stripe.c | 5 +-
drivers/md/dm-thin.c | 76 +++++++++++++++++++++++++-----------------
drivers/md/dm-verity.c | 6 +--
include/linux/device-mapper.h | 4 +-
13 files changed, 88 insertions(+), 104 deletions(-)

--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1262,20 +1262,6 @@ static int crypt_decode_key(u8 *key, cha
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 *t
return DM_MAPIO_SUBMITTED;
}

-static int crypt_status(struct dm_target *ti, status_type_t type,
- char *result, unsigned int maxlen)
+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
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

break;
}
- return 0;
}

static void crypt_postsuspend(struct dm_target *ti)
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -294,8 +294,8 @@ static int delay_map(struct dm_target *t
return delay_bio(dc, dc->read_delay, bio);
}

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

static int delay_iterate_devices(struct dm_target *ti,
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -332,8 +332,8 @@ static int flakey_end_io(struct dm_targe
return error;
}

-static int flakey_status(struct dm_target *ti, status_type_t type,
- char *result, unsigned int maxlen)
+static void flakey_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned int maxlen)
{
unsigned sz = 0;
struct flakey_c *fc = ti->private;
@@ -363,7 +363,6 @@ static int flakey_status(struct dm_targe

break;
}
- return 0;
}

static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1066,6 +1066,7 @@ static void retrieve_status(struct dm_ta
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_ta
}

/* Get the status/table string from the target driver */
- if (ti->type->status) {
- if (ti->type->status(ti, type, outptr, remaining)) {
- param->flags |= DM_BUFFER_FULL_FLAG;
- break;
- }
- } else
+ if (ti->type->status)
+ ti->type->status(ti, type, outptr, remaining);
+ else
outptr[0] = '\0';

- outptr += strlen(outptr) + 1;
+ l = strlen(outptr) + 1;
+ if (l == remaining) {
+ param->flags |= DM_BUFFER_FULL_FLAG;
+ break;
+ }
+
+ outptr += l;
used = param->data_start + (outptr - outbuf);

outptr = align_ptr(outptr);
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -95,8 +95,8 @@ static int linear_map(struct dm_target *
return DM_MAPIO_REMAPPED;
}

-static int linear_status(struct dm_target *ti, status_type_t type,
- char *result, unsigned int maxlen)
+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_targe
(unsigned long long)lc->start);
break;
}
- return 0;
}

static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1343,8 +1343,8 @@ static void multipath_resume(struct dm_t
* [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,
- char *result, unsigned int maxlen)
+static void multipath_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned int maxlen)
{
int sz = 0;
unsigned long flags;
@@ -1447,8 +1447,6 @@ static int multipath_status(struct dm_ta
}

spin_unlock_irqrestore(&m->lock, flags);
-
- return 0;
}

static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1067,8 +1067,8 @@ static int raid_map(struct dm_target *ti
return DM_MAPIO_SUBMITTED;
}

-static int raid_status(struct dm_target *ti, status_type_t type,
- char *result, unsigned maxlen)
+static void raid_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned maxlen)
{
struct raid_set *rs = ti->private;
unsigned raid_param_cnt = 1; /* at least 1 for chunksize */
@@ -1203,8 +1203,6 @@ static int raid_status(struct dm_target
DMEMIT(" -");
}
}
-
- return 0;
}

static int raid_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -1362,8 +1362,8 @@ static char device_status_char(struct mi
}

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

static int mirror_iterate_devices(struct dm_target *ti,
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1845,8 +1845,8 @@ static void snapshot_merge_resume(struct
start_merge(s);
}

-static int snapshot_status(struct dm_target *ti, status_type_t type,
- char *result, unsigned int maxlen)
+static void snapshot_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned int maxlen)
{
unsigned sz = 0;
struct dm_snapshot *snap = ti->private;
@@ -1892,8 +1892,6 @@ static int snapshot_status(struct dm_tar
maxlen - sz);
break;
}
-
- return 0;
}

static int snapshot_iterate_devices(struct dm_target *ti,
@@ -2148,8 +2146,8 @@ static void origin_resume(struct dm_targ
ti->split_io = get_origin_minimum_chunksize(dev->bdev);
}

-static int origin_status(struct dm_target *ti, status_type_t type, char *result,
- unsigned int maxlen)
+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_targe
snprintf(result, maxlen, "%s", dev->name);
break;
}
-
- return 0;
}

static int origin_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -302,8 +302,8 @@ static int stripe_map(struct dm_target *
*
*/

-static int stripe_status(struct dm_target *ti,
- status_type_t type, char *result, unsigned int maxlen)
+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;
char buffer[sc->stripes + 1];
@@ -330,7 +330,6 @@ static int stripe_status(struct dm_targe
(unsigned long long)sc->stripe[i].physical_start);
break;
}
- return 0;
}

static int stripe_end_io(struct dm_target *ti, struct bio *bio,
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2325,8 +2325,8 @@ static int pool_message(struct dm_target
* <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,
- char *result, unsigned maxlen)
+static void pool_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned maxlen)
{
int r, count;
unsigned sz = 0;
@@ -2343,32 +2343,41 @@ static int pool_status(struct dm_target

switch (type) {
case STATUSTYPE_INFO:
- r = dm_pool_get_metadata_transaction_id(pool->pmd,
- &transaction_id);
- if (r)
- return r;
-
- r = dm_pool_get_free_metadata_block_count(pool->pmd,
- &nr_free_blocks_metadata);
- 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) {
+ 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

break;
}
+ return;

- return 0;
+err:
+ DMEMIT("Error");
}

static int pool_iterate_devices(struct dm_target *ti,
@@ -2659,8 +2670,8 @@ static void thin_postsuspend(struct dm_t
/*
* <nr mapped sectors> <highest mapped sector>
*/
-static int thin_status(struct dm_target *ti, status_type_t type,
- char *result, unsigned maxlen)
+static void thin_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned maxlen)
{
int r;
ssize_t sz = 0;
@@ -2674,12 +2685,16 @@ static int thin_status(struct dm_target
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
}
}

- return 0;
+ return;
+
+err:
+ DMEMIT("Error");
}

static int thin_iterate_devices(struct dm_target *ti,
--- a/drivers/md/dm-verity.c
+++ b/drivers/md/dm-verity.c
@@ -514,8 +514,8 @@ static int verity_map(struct dm_target *
/*
* Status: V (valid) or C (corruption found)
*/
-static int verity_status(struct dm_target *ti, status_type_t type,
- char *result, unsigned maxlen)
+static void verity_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned maxlen)
{
struct dm_verity *v = ti->private;
unsigned sz = 0;
@@ -546,8 +546,6 @@ static int verity_status(struct dm_targe
DMEMIT("%02x", v->salt[x]);
break;
}
-
- return 0;
}

static int verity_ioctl(struct dm_target *ti, unsigned cmd,
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -72,8 +72,8 @@ typedef void (*dm_postsuspend_fn) (struc
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,
- char *result, unsigned int maxlen);
+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);