Messages in this thread Patch in this message | | | From | Kees Cook <> | Subject | [PATCH v2 17/30] scsi: Define usercopy region in scsi_sense_cache slab cache | Date | Mon, 28 Aug 2017 14:34:58 -0700 |
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From: David Windsor <dave@nullcore.net>
SCSI sense buffers, stored in struct scsi_cmnd.sense and therefore contained in the scsi_sense_cache slab cache, need to be copied to/from userspace.
cache object allocation: drivers/scsi/scsi_lib.c: scsi_select_sense_cache(...): return ... ? scsi_sense_isadma_cache : scsi_sense_cache
scsi_alloc_sense_buffer(...): return kmem_cache_alloc_node(scsi_select_sense_cache(), ...);
scsi_init_request(...): ... cmd->sense_buffer = scsi_alloc_sense_buffer(...); ... cmd->req.sense = cmd->sense_buffer
example usage trace:
block/scsi_ioctl.c: (inline from sg_io) blk_complete_sghdr_rq(...): struct scsi_request *req = scsi_req(rq); ... copy_to_user(..., req->sense, len)
scsi_cmd_ioctl(...): sg_io(...);
In support of usercopy hardening, this patch defines a region in the scsi_sense_cache slab cache in which userspace copy operations are allowed.
This region is known as the slab cache's usercopy region. Slab caches can now check that each copy operation involving cache-managed memory falls entirely within the slab's usercopy region.
Signed-off-by: David Windsor <dave@nullcore.net> [kees: adjust commit log, provide usage trace] Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: linux-scsi@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/scsi/scsi_lib.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index f6097b89d5d3..f1c6bd56dd5b 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -77,14 +77,15 @@ int scsi_init_sense_cache(struct Scsi_Host *shost) if (shost->unchecked_isa_dma) { scsi_sense_isadma_cache = kmem_cache_create("scsi_sense_cache(DMA)", - SCSI_SENSE_BUFFERSIZE, 0, - SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA, NULL); + SCSI_SENSE_BUFFERSIZE, 0, + SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA, NULL); if (!scsi_sense_isadma_cache) ret = -ENOMEM; } else { scsi_sense_cache = - kmem_cache_create("scsi_sense_cache", - SCSI_SENSE_BUFFERSIZE, 0, SLAB_HWCACHE_ALIGN, NULL); + kmem_cache_create_usercopy("scsi_sense_cache", + SCSI_SENSE_BUFFERSIZE, 0, SLAB_HWCACHE_ALIGN, + 0, SCSI_SENSE_BUFFERSIZE, NULL); if (!scsi_sense_cache) ret = -ENOMEM; } -- 2.7.4
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