linux-toradex.git/drivers/md/dm-crypt.c, branch v3.10.78

dm crypt: fix access beyond the end of allocated space

2014-10-05T21:54:12+00:00

commit d49ec52ff6ddcda178fc2476a109cf1bd1fa19ed upstream.

The DM crypt target accesses memory beyond allocated space resulting in
a crash on 32 bit x86 systems.

This bug is very old (it dates back to 2.6.25 commit 3a7f6c990ad04 "dm
crypt: use async crypto").  However, this bug was masked by the fact
that kmalloc rounds the size up to the next power of two.  This bug
wasn't exposed until 3.17-rc1 commit 298a9fa08a ("dm crypt: use per-bio
data").  By switching to using per-bio data there was no longer any
padding beyond the end of a dm-crypt allocated memory block.

To minimize allocation overhead dm-crypt puts several structures into one
block allocated with kmalloc.  The block holds struct ablkcipher_request,
cipher-specific scratch pad (crypto_ablkcipher_reqsize(any_tfm(cc))),
struct dm_crypt_request and an initialization vector.

The variable dmreq_start is set to offset of struct dm_crypt_request
within this memory block.  dm-crypt allocates the block with this size:
cc->dmreq_start + sizeof(struct dm_crypt_request) + cc->iv_size.

When accessing the initialization vector, dm-crypt uses the function
iv_of_dmreq, which performs this calculation: ALIGN((unsigned long)(dmreq
+ 1), crypto_ablkcipher_alignmask(any_tfm(cc)) + 1).

dm-crypt allocated "cc->iv_size" bytes beyond the end of dm_crypt_request
structure.  However, when dm-crypt accesses the initialization vector, it
takes a pointer to the end of dm_crypt_request, aligns it, and then uses
it as the initialization vector.  If the end of dm_crypt_request is not
aligned on a crypto_ablkcipher_alignmask(any_tfm(cc)) boundary the
alignment causes the initialization vector to point beyond the allocated
space.

Fix this bug by calculating the variable iv_size_padding and adding it
to the allocated size.

Also correct the alignment of dm_crypt_request.  struct dm_crypt_request
is specific to dm-crypt (it isn't used by the crypto subsystem at all),
so it is aligned on __alignof__(struct dm_crypt_request).

Also align per_bio_data_size on ARCH_KMALLOC_MINALIGN, so that it is
aligned as if the block was allocated with kmalloc.

Reported-by: Krzysztof Kolasa 
Tested-by: Milan Broz 
Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

dm crypt: fix cpu hotplug crash by removing per-cpu structure

2014-06-07T20:25:39+00:00

commit 610f2de3559c383caf8fbbf91e9968102dff7ca0 upstream.

The DM crypt target used per-cpu structures to hold pointers to a
ablkcipher_request structure.  The code assumed that the work item keeps
executing on a single CPU, so it didn't use synchronization when
accessing this structure.

If a CPU is disabled by writing 0 to /sys/devices/system/cpu/cpu*/online,
the work item could be moved to another CPU.  This causes dm-crypt
crashes, like the following, because the code starts using an incorrect
ablkcipher_request:

 smpboot: CPU 7 is now offline
 BUG: unable to handle kernel NULL pointer dereference at 0000000000000130
 IP: [] crypt_convert+0x12d/0x3c0 [dm_crypt]
 ...
 Call Trace:
  [] ? kcryptd_crypt+0x305/0x470 [dm_crypt]
  [] ? finish_task_switch+0x40/0xc0
  [] ? process_one_work+0x168/0x470
  [] ? worker_thread+0x10b/0x390
  [] ? manage_workers.isra.26+0x290/0x290
  [] ? kthread+0xaf/0xc0
  [] ? kthread_create_on_node+0x120/0x120
  [] ? ret_from_fork+0x7c/0xb0
  [] ? kthread_create_on_node+0x120/0x120

Fix this bug by removing the per-cpu definition.  The structure
ablkcipher_request is accessed via a pointer from convert_context.
Consequently, if the work item is rescheduled to a different CPU, the
thread still uses the same ablkcipher_request.

This change may undermine performance improvements intended by commit
c0297721 ("dm crypt: scale to multiple cpus") on select hardware.  In
practice no performance difference was observed on recent hardware.  But
regardless, correctness is more important than performance.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Greg Kroah-Hartman

block: Convert some code to bio_for_each_segment_all()

2013-03-23T21:26:30+00:00

More prep work for immutable bvecs:

A few places in the code were either open coding or using the wrong
version - fix.

After we introduce the bvec iter, it'll no longer be possible to modify
the biovec through bio_for_each_segment_all() - it doesn't increment a
pointer to the current bvec, you pass in a struct bio_vec (not a
pointer) which is updated with what the current biovec would be (taking
into account bi_bvec_done and bi_size).

So because of that it's more worthwhile to be consistent about
bio_for_each_segment()/bio_for_each_segment_all() usage.

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
CC: NeilBrown 
CC: Alasdair Kergon 
CC: dm-devel@redhat.com
CC: Alexander Viro

dm: rename request variables to bios

2013-03-01T22:45:47+00:00

Use 'bio' in the name of variables and functions that deal with
bios rather than 'request' to avoid confusion with the normal
block layer use of 'request'.

No functional changes.

Signed-off-by: Alasdair G Kergon

dm: fix truncated status strings

2013-03-01T22:45:44+00:00

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.

Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm: remove map_info

2012-12-21T20:23:41+00:00

This patch removes map_info from bio-based device mapper targets.
map_info is still used for request-based targets.

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

block: Add bio_clone_bioset(), bio_clone_kmalloc()

2012-09-09T08:35:39+00:00

Previously, there was bio_clone() but it only allocated from the fs bio
set; as a result various users were open coding it and using
__bio_clone().

This changes bio_clone() to become bio_clone_bioset(), and then we add
bio_clone() and bio_clone_kmalloc() as wrappers around it, making use of
the functionality the last patch adedd.

This will also help in a later patch changing how bio cloning works.

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
CC: NeilBrown 
CC: Alasdair Kergon 
CC: Boaz Harrosh 
CC: Jeff Garzik 
Acked-by: Jeff Garzik 
Signed-off-by: Jens Axboe

block: Generalized bio pool freeing

2012-09-09T08:35:38+00:00

With the old code, when you allocate a bio from a bio pool you have to
implement your own destructor that knows how to find the bio pool the
bio was originally allocated from.

This adds a new field to struct bio (bi_pool) and changes
bio_alloc_bioset() to use it. This makes various bio destructors
unnecessary, so they're then deleted.

v6: Explain the temporary if statement in bio_put

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
CC: NeilBrown 
CC: Alasdair Kergon 
CC: Nicholas Bellinger 
CC: Lars Ellenberg 
Acked-by: Tejun Heo 
Acked-by: Nicholas Bellinger 
Signed-off-by: Jens Axboe

dm thin: commit before gathering status

2012-07-27T14:08:16+00:00

Commit outstanding metadata before returning the status for a dm thin
pool so that the numbers reported are as up-to-date as possible.

The commit is not performed if the device is suspended or if
the DM_NOFLUSH_FLAG is supplied by userspace and passed to the target
through a new 'status_flags' parameter in the target's dm_status_fn.

The userspace dmsetup tool will support the --noflush flag with the
'dmsetup status' and 'dmsetup wait' commands from version 1.02.76
onwards.

Tested-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm: use bool bitfields in struct dm_target

2012-07-27T14:08:08+00:00

Use boolean bit fields for flags in struct dm_target.

Signed-off-by: Alasdair G Kergon