linux-stable.git/drivers/block/nbd.c, branch linux-6.5.y

nbd: fix uaf in nbd_open

2023-11-20T10:57:23+00:00

[ Upstream commit 327462725b0f759f093788dfbcb2f1fd132f956b ]

Commit 4af5f2e03013 ("nbd: use blk_mq_alloc_disk and
blk_cleanup_disk") cleans up disk by blk_cleanup_disk() and it won't set
disk->private_data as NULL as before. UAF may be triggered in nbd_open()
if someone tries to open nbd device right after nbd_put() since nbd has
been free in nbd_dev_remove().

Fix this by implementing ->free_disk and free private data in it.

Fixes: 4af5f2e03013 ("nbd: use blk_mq_alloc_disk and blk_cleanup_disk")
Signed-off-by: Li Lingfeng 
Reviewed-by: Josef Bacik 
Link: https://lore.kernel.org/r/20231107103435.2074904-1-lilingfeng@huaweicloud.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: replace fmode_t with a block-specific type for block open flags

2023-06-12T14:04:05+00:00

The only overlap between the block open flags mapped into the fmode_t and
other uses of fmode_t are FMODE_READ and FMODE_WRITE.  Define a new
blk_mode_t instead for use in blkdev_get_by_{dev,path}, ->open and
->ioctl and stop abusing fmode_t.

Signed-off-by: Christoph Hellwig 
Acked-by: Jack Wang 		[rnbd]
Reviewed-by: Hannes Reinecke 
Reviewed-by: Christian Brauner 
Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de
Signed-off-by: Jens Axboe

block: remove the unused mode argument to ->release

2023-06-12T14:04:04+00:00

The mode argument to the ->release block_device_operation is never used,
so remove it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Hannes Reinecke 
Acked-by: Christian Brauner 
Acked-by: Jack Wang 			[rnbd]
Link: https://lore.kernel.org/r/20230608110258.189493-10-hch@lst.de
Signed-off-by: Jens Axboe

block: pass a gendisk to ->open

2023-06-12T14:04:04+00:00

->open is only called on the whole device.  Make that explicit by
passing a gendisk instead of the block_device.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Hannes Reinecke 
Acked-by: Christian Brauner 
Acked-by: Jack Wang 		[rnbd]
Link: https://lore.kernel.org/r/20230608110258.189493-9-hch@lst.de
Signed-off-by: Jens Axboe

nbd: Add the maximum limit of allocated index in nbd_dev_add

2023-06-07T13:50:48+00:00

If the index allocated by idr_alloc greater than MINORMASK >> part_shift,
the device number will overflow, resulting in failure to create a block
device.

Fix it by imiting the size of the max allocation.

Signed-off-by: Zhong Jinghua 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20230605122159.2134384-1-zhongjinghua@huaweicloud.com
Signed-off-by: Jens Axboe

nbd: Fix debugfs_create_dir error checking

2023-05-12T14:56:33+00:00

The debugfs_create_dir function returns ERR_PTR in case of error, and the
only correct way to check if an error occurred is 'IS_ERR' inline function.
This patch will replace the null-comparison with IS_ERR.

Signed-off-by: Ivan Orlov 
Link: https://lore.kernel.org/r/20230512130533.98709-1-ivan.orlov0322@gmail.com
Signed-off-by: Jens Axboe

block nbd: use req.cookie instead of req.handle

2023-04-28T01:15:11+00:00

The NBD spec was recently changed [1] to refer to the opaque client
identifier as a 'cookie' rather than a 'handle', but has for a much
longer time listed it as a 64-bit value, and declares that all values
in the NBD protocol are sent in network byte order (big-endian).

Because the value is opaque to the server, it doesn't usually matter
what endianness we send as the client - as long as we are consistent
that either we byte-swap on both write and read, or on neither, then
we can match server replies back to our requests.  That said, our
internal use of the cookie is as a 64-bit number (well, as two 32-bit
numbers concatenated together), rather than as 8 individual bytes; so
prior to this commit, we ARE leaking the native endianness of our
internals as a client out to the server.  We don't know of any server
that will actually inspect the opaque value and behave differently
depending on whether a little-endian or big-endian client is sending
requests, but since we DO log the cookie value, a wireshark capture of
the network traffic is easier to correlate back to the kernel traffic
of a big-endian host (where the u64 and char[8] representations are
the same) than of a little-endian host (where if wireshark honors the
NBD spec and displays a u64 in network byte order, it is byte-swapped
from what the kernel logged).

The fix in this patch is thus two-part: it now consistently uses
network byte order for the opaque value (no difference to a big-endian
machine, but an extra byteswap on a little-endian machine; probably in
the noise compared to the overhead of network traffic in general), and
now uses a 64-bit integer instead of char[8] as its preferred access
to the opaque value (direct assignment instead of memcpy()).

Signed-off-by: Eric Blake 
Reviewed-by: Josef Bacik 
Link: https://lore.kernel.org/r/20230410180611.1051618-4-eblake@redhat.com
Signed-off-by: Jens Axboe

block/drivers: remove dead clear of random flag

2023-04-25T14:02:11+00:00

QUEUE_FLAG_ADD_RANDOM is not set before we clear it for "null_blk",
"brd", "nbd", "zram", and "bcache" since by default we don't set
"QUEUE_FLAG_ADD_RANDOM" to MQ ops.

Remove dead clear of QUEUE_FLAG_ADD_RANDOM in above listed drivers.

Signed-off-by: Chaitanya Kulkarni 
Reviewed-by: Sergey Senozhatsky  #zram
Link: https://lore.kernel.org/r/20230424234628.45544-2-kch@nvidia.com
Signed-off-by: Jens Axboe

nbd: fix incomplete validation of ioctl arg

2023-04-20T19:43:44+00:00

We tested and found an alarm caused by nbd_ioctl arg without verification.
The UBSAN warning calltrace like below:

UBSAN: Undefined behaviour in fs/buffer.c:1709:35
signed integer overflow:
-9223372036854775808 - 1 cannot be represented in type 'long long int'
CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1
Hardware name: linux,dummy-virt (DT)
Call trace:
 dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78
 show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x170/0x1dc lib/dump_stack.c:118
 ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161
 handle_overflow+0x188/0x1dc lib/ubsan.c:192
 __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206
 __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709
 block_write_full_page+0x1f0/0x280 fs/buffer.c:2934
 blkdev_writepage+0x34/0x40 fs/block_dev.c:607
 __writepage+0x68/0xe8 mm/page-writeback.c:2305
 write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240
 generic_writepages+0xdc/0x148 mm/page-writeback.c:2329
 blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114
 do_writepages+0xd4/0x250 mm/page-writeback.c:2344

The reason for triggering this warning is __block_write_full_page()
-> i_size_read(inode) - 1 overflow.
inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> bytesize.
We think it is necessary to limit the size of arg to prevent errors.

Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int.
Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine),
it will become 1 after the coercion, which will return unexpected results.

Fix it by adding checks to prevent passing in too large numbers.

Signed-off-by: Zhong Jinghua 
Reviewed-by: Yu Kuai 
Reviewed-by: Josef Bacik 
Link: https://lore.kernel.org/r/20230206145805.2645671-1-zhongjinghua@huawei.com
Signed-off-by: Jens Axboe

nbd: use the structured req attr check

2023-03-14T20:17:13+00:00

Use the macro for checking presence of required attributes.
It has the advantage of reporting to the user which attr
was missing in a machine-readable format (extack).

Reviewed-by: Josef Bacik 
Signed-off-by: Jakub Kicinski 
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20230224021301.1630703-2-kuba@kernel.org
Signed-off-by: Jens Axboe