linux-toradex.git/drivers/md/dm-ioctl.c, branch v3.2.42

dm: fix truncated status strings

2013-03-20T15:03:20+00:00

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 
Signed-off-by: Alasdair G Kergon 
[bwh: Backported to 3.2:
 - Adjust context
 - dm_status_fn doesn't take a status_flags parameter
 - Bump the last component of each current version (verified not to
   match any version used in mainline)
 - Drop changes to dm-verity]
Signed-off-by: Ben Hutchings

dm ioctl: prevent unsafe change to dm_ioctl data_size

2013-01-03T03:33:47+00:00

commit e910d7ebecd1aac43125944a8641b6cb1a0dfabe upstream.

Abort dm ioctl processing if userspace changes the data_size parameter
after we validated it but before we finished copying the data buffer
from userspace.

The dm ioctl parameters are processed in the following sequence:
 1. ctl_ioctl() calls copy_params();
 2. copy_params() makes a first copy of the fixed-sized portion of the
    userspace parameters into the local variable "tmp";
 3. copy_params() then validates tmp.data_size and allocates a new
    structure big enough to hold the complete data and copies the whole
    userspace buffer there;
 4. ctl_ioctl() reads userspace data the second time and copies the whole
    buffer into the pointer "param";
 5. ctl_ioctl() reads param->data_size without any validation and stores it
    in the variable "input_param_size";
 6. "input_param_size" is further used as the authoritative size of the
    kernel buffer.

The problem is that userspace code could change the contents of user
memory between steps 2 and 4.  In particular, the data_size parameter
can be changed to an invalid value after the kernel has validated it.
This lets userspace force the kernel to access invalid kernel memory.

The fix is to ensure that the size has not changed at step 4.

This patch shouldn't have a security impact because CAP_SYS_ADMIN is
required to run this code, but it should be fixed anyway.

Reported-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon 
Signed-off-by: Ben Hutchings

dm ioctl: do not leak argv if target message only contains whitespace

2012-03-12T19:31:41+00:00

commit 902c6a96a7cb9c50d2a8aed1788efad0a5d8f04c upstream.

If 'argc' is zero we jump to the 'out:' label, but this leaks the
(unused) memory that 'dm_split_args()' allocated for 'argv' if the
string being split consisted entirely of whitespace.  Jump to the
'out_argv:' label instead to free up that memory.

Signed-off-by: Jesper Juhl 
Signed-off-by: Alasdair G Kergon 
Signed-off-by: Greg Kroah-Hartman

dm table: add immutable feature

2011-10-31T20:19:04+00:00

Introduce DM_TARGET_IMMUTABLE to indicate that the target type cannot be mixed
with any other target type, and once loaded into a device, it cannot be
replaced with a table containing a different type.

The thin provisioning pool device will use this.

Signed-off-by: Alasdair G Kergon

dm ioctl: forbid multiple device specifiers

2011-08-02T11:32:06+00:00

Exactly one of name, uuid or device must be specified when referencing
an existing device.  This removes the ambiguity (risking the wrong
device being updated) if two conflicting parameters were specified.
Previously one parameter got used and any others were ignored silently.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm ioctl: introduce __get_dev_cell

2011-08-02T11:32:06+00:00

Move logic to find device based on major/minor number to a separate
function __get_dev_cell (similar to __get_uuid_cell and __get_name_cell).
This makes the function __find_device_hash_cell more straightforward.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm ioctl: fill in device parameters in more ioctls

2011-08-02T11:32:06+00:00

Move parameter filling from find_device to __find_device_hash_cell.

This patch causes ioctls using __find_device_hash_cell
(DM_DEV_REMOVE_CMD, DM_DEV_SUSPEND_CMD - resume, DM_TABLE_CLEAR_CMD)
to return device parameters, bringing them into line with the other
ioctls.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm ioctl: prevent empty message

2011-08-02T11:32:03+00:00

Detect invalid empty messages in core dm instead of requiring every target to
check this.

Signed-off-by: Alasdair G Kergon

dm ioctl: add flag to wipe buffers for secure data

2011-03-24T13:54:30+00:00

Add DM_SECURE_DATA_FLAG which userspace can use to ensure
that all buffers allocated for dm-ioctl are wiped
immediately after use.

The user buffer is wiped as well (we do not want to keep
and return sensitive data back to userspace if the flag is set).

Wiping is useful for cryptsetup to ensure that the key
is present in memory only in defined places and only
for the time needed.

(For crypt, key can be present in table during load or table
status, wait and message commands).

Signed-off-by: Milan Broz 
Signed-off-by: Alasdair G Kergon

dm ioctl: prepare for crypt key wiping

2011-03-24T13:54:28+00:00

Prepare code for implementing buffer wipe flag.
No functional change in this patch.

Signed-off-by: Milan Broz 
Acked-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon