PING^2 Re: [PATCH v2 00/14] Corrections and customization of theSG_IO command whitelist (CVE-2012-4542)

[Paolo Bonzini]

Il 20/02/2013 17:12, Paolo Bonzini ha scritto:
> Il 06/02/2013 16:15, Paolo Bonzini ha scritto:
>> This series regards the whitelist that is used for the SG_IO ioctl.  This
>> whitelist has three problems:
>>
>> * the bitmap of allowed commands is designed for MMC devices (roughly,
>>   "play/burn CDs without requiring root") but some opcodes overlap across SCSI
>>   device classes and have different meanings for different classes.
>>
>> * also because the bitmap of allowed commands is designed for MMC devices
>>   only, some commands are missing even though they are generally useful and
>>   not insecure.  At least not more insecure than anything else you can
>>   do if you have access to /dev/sdX or /dev/stX nodes.
>>
>> * the whitelist can be disabled per-process but not per-disk.  In addition,
>>   the required capability (CAP_SYS_RAWIO) gives access to a range of other 
>>   resources, enough to make it insecure.
>>
>> The series corrects these problems.  Patches 1-4 solve the first problem,
>> which also has an assigned CVE, by using different bitmaps for the various
>> device classes.  Patches 5-11 solve the second by adding more commands
>> to the bitmaps.  Patches 12 and 13 solve the third, and were already
>> posted but ignored by the maintainers despite multiple pings.
>>
>> Note: checkpatch hates the formatting of the command table.  I know about this,
>> and ensured that there are no errors in the rest of the code.  The current
>> formatting is IMHO quite handy, and roughly based on the files available
>> from the SCSI standard body.
>>
>> Ok for the next merge window?
>>
>> Paolo
>>
>> v1->v2: remove 2 MMC commands and 6 SBC commands (see patches 6 and 9
>>         for details).  Added patch 14 and added a few more scanner
>>         commands based on SANE (scanners are not whitelisted by default,
>>         also were not in v1, but this makes it possible to opt into the
>>         whitelist out of paranoia).  Removed C++ comments.  Removed the
>>         large #if 0'd list of commands that the kernel does not pass
>>         though.  Marked blk_set_cmd_filter_defaults as __init.
> 
> Ping...
> 
> Jens/James, is anyone going to pick this up for 3.9?

Another month has passed, Ping^2...

Paolo

> Paolo
> 
>>
>> Paolo Bonzini (14):
>>   sg_io: pass request_queue to blk_verify_command
>>   sg_io: reorganize list of allowed commands
>>   sg_io: use different default filters for each device class
>>   sg_io: resolve conflicts between commands assigned to multiple
>>     classes (CVE-2012-4542)
>>   sg_io: whitelist a few more commands for rare & obsolete device types
>>   sg_io: whitelist another command for multimedia devices
>>   sg_io: whitelist a few more commands for media changers
>>   sg_io: whitelist a few more commands for tapes
>>   sg_io: whitelist a few more commands for disks
>>   sg_io: whitelist a few obsolete commands
>>   sg_io: mark blk_set_cmd_filter_defaults as __init
>>   sg_io: remove remnants of sysfs SG_IO filters
>>   sg_io: introduce unpriv_sgio queue flag
>>   sg_io: use unpriv_sgio to disable whitelisting for scanners
>>
>>  Documentation/block/queue-sysfs.txt |    8 +
>>  block/blk-sysfs.c                   |   33 +++
>>  block/bsg.c                         |    2 +-
>>  block/scsi_ioctl.c                  |  369 ++++++++++++++++++++++++++---------
>>  drivers/scsi/scsi_scan.c            |   14 ++-
>>  drivers/scsi/sg.c                   |    6 +-
>>  include/linux/blkdev.h              |    8 +-
>>  include/linux/genhd.h               |    9 -
>>  include/scsi/scsi.h                 |    3 +
>>  9 files changed, 344 insertions(+), 108 deletions(-)
>>
> 

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