Commit 9a72a024 authored by Jingbo Xu's avatar Jingbo Xu Committed by Jens Axboe
Browse files

block: fine-granular CAP_SYS_ADMIN for Persistent Reservation 



Allow of unprivileged Persistent Reservation operations on devices
if the write permission check on the device node has passed.

brw-rw---- 1 root disk 259, 0 Jun 13 07:09 /dev/nvme0n1

In the example above, the "disk" group of nvme0n1 is also allowed to
make reservations on the device even without CAP_SYS_ADMIN.

Signed-off-by: default avatarJingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230613084008.93795-3-jefflexu@linux.alibaba.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 12629621

block/ioctl.c

+22 −19
Original line number Diff line number Diff line
@@ -254,7 +254,7 @@ int blkdev_compat_ptr_ioctl(struct block_device *bdev, blk_mode_t mode, 
EXPORT_SYMBOL(blkdev_compat_ptr_ioctl);

#endif



static bool blkdev_pr_allowed(struct block_device *bdev)

static bool blkdev_pr_allowed(struct block_device *bdev, blk_mode_t mode)

{

	/* no sense to make reservations for partitions */

	if (bdev_is_partition(bdev))
@@ -262,17 +262,20 @@ static bool blkdev_pr_allowed(struct block_device *bdev) 


	if (capable(CAP_SYS_ADMIN))

		return true;



	return false;

	/*

	 * Only allow unprivileged reservations if the file descriptor is open

	 * for writing.

	 */

	return mode & BLK_OPEN_WRITE;

}



static int blkdev_pr_register(struct block_device *bdev,

static int blkdev_pr_register(struct block_device *bdev, blk_mode_t mode,

		struct pr_registration __user *arg)

{

	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;

	struct pr_registration reg;



	if (!blkdev_pr_allowed(bdev))

	if (!blkdev_pr_allowed(bdev, mode))

		return -EPERM;

	if (!ops || !ops->pr_register)

		return -EOPNOTSUPP;
@@ -284,13 +287,13 @@ static int blkdev_pr_register(struct block_device *bdev, 
	return ops->pr_register(bdev, reg.old_key, reg.new_key, reg.flags);

}



static int blkdev_pr_reserve(struct block_device *bdev,

static int blkdev_pr_reserve(struct block_device *bdev, blk_mode_t mode,

		struct pr_reservation __user *arg)

{

	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;

	struct pr_reservation rsv;



	if (!blkdev_pr_allowed(bdev))

	if (!blkdev_pr_allowed(bdev, mode))

		return -EPERM;

	if (!ops || !ops->pr_reserve)

		return -EOPNOTSUPP;
@@ -302,13 +305,13 @@ static int blkdev_pr_reserve(struct block_device *bdev, 
	return ops->pr_reserve(bdev, rsv.key, rsv.type, rsv.flags);

}



static int blkdev_pr_release(struct block_device *bdev,

static int blkdev_pr_release(struct block_device *bdev, blk_mode_t mode,

		struct pr_reservation __user *arg)

{

	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;

	struct pr_reservation rsv;



	if (!blkdev_pr_allowed(bdev))

	if (!blkdev_pr_allowed(bdev, mode))

		return -EPERM;

	if (!ops || !ops->pr_release)

		return -EOPNOTSUPP;
@@ -320,13 +323,13 @@ static int blkdev_pr_release(struct block_device *bdev, 
	return ops->pr_release(bdev, rsv.key, rsv.type);

}



static int blkdev_pr_preempt(struct block_device *bdev,

static int blkdev_pr_preempt(struct block_device *bdev, blk_mode_t mode,

		struct pr_preempt __user *arg, bool abort)

{

	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;

	struct pr_preempt p;



	if (!blkdev_pr_allowed(bdev))

	if (!blkdev_pr_allowed(bdev, mode))

		return -EPERM;

	if (!ops || !ops->pr_preempt)

		return -EOPNOTSUPP;
@@ -338,13 +341,13 @@ static int blkdev_pr_preempt(struct block_device *bdev, 
	return ops->pr_preempt(bdev, p.old_key, p.new_key, p.type, abort);

}



static int blkdev_pr_clear(struct block_device *bdev,

static int blkdev_pr_clear(struct block_device *bdev, blk_mode_t mode,

		struct pr_clear __user *arg)

{

	const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;

	struct pr_clear c;



	if (!blkdev_pr_allowed(bdev))

	if (!blkdev_pr_allowed(bdev, mode))

		return -EPERM;

	if (!ops || !ops->pr_clear)

		return -EOPNOTSUPP;
@@ -546,17 +549,17 @@ static int blkdev_common_ioctl(struct block_device *bdev, blk_mode_t mode, 
	case BLKTRACETEARDOWN:

		return blk_trace_ioctl(bdev, cmd, argp);

	case IOC_PR_REGISTER:

		return blkdev_pr_register(bdev, argp);

		return blkdev_pr_register(bdev, mode, argp);

	case IOC_PR_RESERVE:

		return blkdev_pr_reserve(bdev, argp);

		return blkdev_pr_reserve(bdev, mode, argp);

	case IOC_PR_RELEASE:

		return blkdev_pr_release(bdev, argp);

		return blkdev_pr_release(bdev, mode, argp);

	case IOC_PR_PREEMPT:

		return blkdev_pr_preempt(bdev, argp, false);

		return blkdev_pr_preempt(bdev, mode, argp, false);

	case IOC_PR_PREEMPT_ABORT:

		return blkdev_pr_preempt(bdev, argp, true);

		return blkdev_pr_preempt(bdev, mode, argp, true);

	case IOC_PR_CLEAR:

		return blkdev_pr_clear(bdev, argp);

		return blkdev_pr_clear(bdev, mode, argp);

	default:

		return -ENOIOCTLCMD;

	}