From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seshagiri Holi Subject: RE: [PATCH] mmc: block: fix ABI regression of mmc_blk_ioctl Date: Mon, 7 Mar 2016 11:46:28 +0000 Message-ID: <870544d2b7024a37a4d7964db9cf3125@bgmail102.nvidia.com> References: <1457331857-4953-1-git-send-email-shawn.lin@rock-chips.com> <4aa8686868a640499a9313f4a77ddc46@bgmail102.nvidia.com> <56DD2AE9.7000708@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Return-path: Received: from hqemgate14.nvidia.com ([216.228.121.143]:8784 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751146AbcCGLqf convert rfc822-to-8bit (ORCPT ); Mon, 7 Mar 2016 06:46:35 -0500 In-Reply-To: <56DD2AE9.7000708@rock-chips.com> Content-Language: en-US Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Shawn Lin , Ulf Hansson Cc: "shawn.lin@kernel-upstream.org" , Jonathan Hunter , linux-mmc thanks for the details. Maybe fix from my view is, that the check in function mmc_blk_ioctl(), should move to respective function mmc_blk_ioctl_cmd and mmc_blk_ioctl_multi_cmd. if ((!capable(CAP_SYS_RAWIO)) || (bdev != bdev->bd_contains)) return -EPERM; I think Ulf Hansson can take a final call. -----Original Message----- From: Shawn Lin [mailto:shawn.lin@rock-chips.com] Sent: Monday, March 07, 2016 12:47 PM To: Seshagiri Holi; Ulf Hansson Cc: shawn.lin@rock-chips.com; shawn.lin@kernel-upstream.org; Jonathan Hunter; linux-mmc Subject: Re: [PATCH] mmc: block: fix ABI regression of mmc_blk_ioctl On 2016/3/7 15:04, Seshagiri Holi wrote: > Hi Shawn, > I am not sure how why blkdev_roset is iocl function call is landing in mmc_blk_ioctl. Could it be a IOCTL mapping issue ? > Regards > Seshagiri > Really no. blkdev_ioctl-> case BLKROSET -> blkdev_roset -> __blkdev_driver_ioctl ->disk->fops->ioctl If mmc_blk_ioctl return -EINVAL, that will fails the check of !is_unrecognized_ioctl. Then the code will continue to work. But commit: a5f5774c55a2 ("mmc: block: Add new ioctl to send multi commands") changes the behaviour to check the cmd(BLKROSET) with CAP_SYS_RAWIO firstly. So blkdev_ioctl finally get -EPERM instead of -EINVAL. So the result you can find: remount of /system failed; couldn't make block device writable: Operation not permitted openat(AT_FDCWD, "/dev/block/platform/ff420000.dwmmc/by-name/system", O_RDONLY) = 3 ioctl(3, BLKROSET, 0) = -1 EPERM (Operation not permitted) > > -----Original Message----- > From: Shawn Lin [mailto:shawn.lin@rock-chips.com] > Sent: Monday, March 07, 2016 11:54 AM > To: Ulf Hansson > Cc: Seshagiri Holi; Jonathan Hunter; Shawn Lin; > stable@vger.kernel.org; #@263.net; 4.4.x@263.net > Subject: [PATCH] mmc: block: fix ABI regression of mmc_blk_ioctl > > We should return -EINVAL if cmd is not MMC_IOC_CMD or MMC_IOC_MULTI_CMD, otherwise blkdev_roset will return -EPERM. > > Android-adb calls make_block_device_writable with ioctl(BLKROSET), which will return error, make remount failed: > remount of /system failed; > couldn't make block device writable: Operation not permitted > > openat(AT_FDCWD, "/dev/block/platform/ff420000.dwmmc/by-name/system", > O_RDONLY) = 3 ioctl(3, BLKROSET, 0) = -1 EPERM (Operation not > permitted) > > Fixes: a5f5774c55a2 ("mmc: block: Add new ioctl to send multi > commands") > Cc: # 4.4.x > Signed-off-by: Shawn Lin > --- > > drivers/mmc/card/block.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index > 47bc87d..170f099 100644 > --- a/drivers/mmc/card/block.c > +++ b/drivers/mmc/card/block.c > @@ -688,6 +688,9 @@ cmd_err: > static int mmc_blk_ioctl(struct block_device *bdev, fmode_t mode, > unsigned int cmd, unsigned long arg) > { > + if (cmd != MMC_IOC_CMD && cmd != MMC_IOC_MULTI_CMD) > + return -EINVAL; > + > /* > * The caller must have CAP_SYS_RAWIO, and must be calling this on the > * whole block device, not on a partition. This prevents overspray > -- > 2.3.7 > > > ---------------------------------------------------------------------- > ------------- This email message is for the sole use of the intended > recipient(s) and may contain confidential information. Any > unauthorized review, use, disclosure or distribution is prohibited. > If you are not the intended recipient, please contact the sender by > reply email and destroy all copies of the original message. > ---------------------------------------------------------------------- > ------------- > > > -- Best Regards Shawn Lin