From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752164Ab2AQEHJ (ORCPT ); Mon, 16 Jan 2012 23:07:09 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:53156 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751825Ab2AQEHE convert rfc822-to-8bit (ORCPT ); Mon, 16 Jan 2012 23:07:04 -0500 Message-ID: <1326773222.2819.172.camel@deadeye> Subject: [PATCH stable 3/4] block: fail SCSI passthrough ioctls on partition devices From: Ben Hutchings To: stable@vger.kernel.org Cc: Paolo Bonzini , Linus Torvalds , linux-kernel@vger.kernel.org, Petr Matousek , linux-scsi@vger.kernel.org, Jens Axboe , James Bottomley Date: Tue, 17 Jan 2012 04:07:02 +0000 In-Reply-To: <1326772723.2819.167.camel@deadeye> References: <1326772723.2819.167.camel@deadeye> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.2.2-1 Mime-Version: 1.0 X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paolo Bonzini commit 0bfc96cb77224736dfa35c3c555d37b3646ef35e upstream. Linux allows executing the SG_IO ioctl on a partition or LVM volume, and will pass the command to the underlying block device. This is well-known, but it is also a large security problem when (via Unix permissions, ACLs, SELinux or a combination thereof) a program or user needs to be granted access only to part of the disk. This patch lets partitions forward a small set of harmless ioctls; others are logged with printk so that we can see which ioctls are actually sent. In my tests only CDROM_GET_CAPABILITY actually occurred. Of course it was being sent to a (partition on a) hard disk, so it would have failed with ENOTTY and the patch isn't changing anything in practice. Still, I'm treating it specially to avoid spamming the logs. In principle, this restriction should include programs running with CAP_SYS_RAWIO. If for example I let a program access /dev/sda2 and /dev/sdb, it still should not be able to read/write outside the boundaries of /dev/sda2 independent of the capabilities. However, for now programs with CAP_SYS_RAWIO will still be allowed to send the ioctls. Their actions will still be logged. This patch does not affect the non-libata IDE driver. That driver however already tests for bd != bd->bd_contains before issuing some ioctl; it could be restricted further to forbid these ioctls even for programs running with CAP_SYS_ADMIN/CAP_SYS_RAWIO. Cc: linux-scsi@vger.kernel.org Cc: Jens Axboe Cc: James Bottomley Signed-off-by: Paolo Bonzini [ Make it also print the command name when warning - Linus ] Signed-off-by: Linus Torvalds [bwh: Backport to 2.6.32 - ENOIOCTLCMD does not get converted to ENOTTY, so we must return ENOTTY directly] Signed-off-by: Ben Hutchings --- block/scsi_ioctl.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ drivers/scsi/sd.c | 11 +++++++++-- include/linux/blkdev.h | 1 + 3 files changed, 55 insertions(+), 2 deletions(-) diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c index 114ee29..2be0a97 100644 --- a/block/scsi_ioctl.c +++ b/block/scsi_ioctl.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -689,9 +690,53 @@ int scsi_cmd_ioctl(struct request_queue *q, struct gendisk *bd_disk, fmode_t mod } EXPORT_SYMBOL(scsi_cmd_ioctl); +int scsi_verify_blk_ioctl(struct block_device *bd, unsigned int cmd) +{ + if (bd && bd == bd->bd_contains) + return 0; + + /* Actually none of these is particularly useful on a partition, + * but they are safe. + */ + switch (cmd) { + case SCSI_IOCTL_GET_IDLUN: + case SCSI_IOCTL_GET_BUS_NUMBER: + case SCSI_IOCTL_GET_PCI: + case SCSI_IOCTL_PROBE_HOST: + case SG_GET_VERSION_NUM: + case SG_SET_TIMEOUT: + case SG_GET_TIMEOUT: + case SG_GET_RESERVED_SIZE: + case SG_SET_RESERVED_SIZE: + case SG_EMULATED_HOST: + return 0; + case CDROM_GET_CAPABILITY: + /* Keep this until we remove the printk below. udev sends it + * and we do not want to spam dmesg about it. CD-ROMs do + * not have partitions, so we get here only for disks. + */ + return -ENOTTY; + default: + break; + } + + /* In particular, rule out all resets and host-specific ioctls. */ + printk_ratelimited(KERN_WARNING + "%s: sending ioctl %x to a partition!\n", current->comm, cmd); + + return capable(CAP_SYS_RAWIO) ? 0 : -ENOTTY; +} +EXPORT_SYMBOL(scsi_verify_blk_ioctl); + int scsi_cmd_blk_ioctl(struct block_device *bd, fmode_t mode, unsigned int cmd, void __user *arg) { + int ret; + + ret = scsi_verify_blk_ioctl(bd, cmd); + if (ret < 0) + return ret; + return scsi_cmd_ioctl(bd->bd_disk->queue, bd->bd_disk, mode, cmd, arg); } EXPORT_SYMBOL(scsi_cmd_blk_ioctl); diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 2dd1b73..fd8145f 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -817,6 +817,10 @@ static int sd_ioctl(struct block_device *bdev, fmode_t mode, SCSI_LOG_IOCTL(1, printk("sd_ioctl: disk=%s, cmd=0x%x\n", disk->disk_name, cmd)); + error = scsi_verify_blk_ioctl(bdev, cmd); + if (error < 0) + return error; + /* * If we are in the middle of error recovery, don't let anyone * else try and use this device. Also, if error recovery fails, it @@ -996,6 +1000,11 @@ static int sd_compat_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg) { struct scsi_device *sdev = scsi_disk(bdev->bd_disk)->device; + int ret; + + ret = scsi_verify_blk_ioctl(bdev, cmd); + if (ret < 0) + return ret; /* * If we are in the middle of error recovery, don't let anyone @@ -1007,8 +1016,6 @@ static int sd_compat_ioctl(struct block_device *bdev, fmode_t mode, return -ENODEV; if (sdev->host->hostt->compat_ioctl) { - int ret; - ret = sdev->host->hostt->compat_ioctl(sdev, cmd, (void __user *)arg); return ret; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 63070ad..5eb6cb0 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -777,6 +777,7 @@ extern void blk_plug_device(struct request_queue *); extern void blk_plug_device_unlocked(struct request_queue *); extern int blk_remove_plug(struct request_queue *); extern void blk_recount_segments(struct request_queue *, struct bio *); +extern int scsi_verify_blk_ioctl(struct block_device *, unsigned int); extern int scsi_cmd_blk_ioctl(struct block_device *, fmode_t, unsigned int, void __user *); extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t, -- 1.7.8.2