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[173.164.112.133]) by smtp.gmail.com with ESMTPSA id z127sm2031068pfb.64.2017.08.28.14.35.21 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 28 Aug 2017 14:35:25 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , "James E.J. Bottomley" , "Martin K. Petersen" , linux-scsi@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Subject: [PATCH v2 17/30] scsi: Define usercopy region in scsi_sense_cache slab cache Date: Mon, 28 Aug 2017 14:34:58 -0700 Message-Id: <1503956111-36652-18-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1503956111-36652-1-git-send-email-keescook@chromium.org> References: <1503956111-36652-1-git-send-email-keescook@chromium.org> Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: David Windsor 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 [kees: adjust commit log, provide usage trace] Cc: "James E.J. Bottomley" Cc: "Martin K. Petersen" Cc: linux-scsi@vger.kernel.org Signed-off-by: Kees Cook --- 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; }