Commit d96acf38 authored by Li Lingfeng's avatar Li Lingfeng
Browse files

block: Add config option to show info about opening a mounted device for write 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8S3GW


CVE: NA

---------------------------

When writing to a mounted block device is allowed, we need to identify
which processes may write to the block device to prevent the file system
from being damaged in silence.

Signed-off-by: default avatarLi Lingfeng <lilingfeng3@huawei.com>
parent bf779220

block/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -259,6 +259,13 @@ config BLK_DEV_DETECT_WRITING_PART0 
	  As a supplement to BLK_DEV_WRITE_MOUNTED, enabling this

	  to detect the scenario above.



config BLK_DEV_WRITE_MOUNTED_DUMP

	bool "Dump info when detecting conflict of opening block device"

	default n

	help

	  Enabling this to dump info when opening mounted block devices

	  for write or trying to mount write opened block devices.



source "block/partitions/Kconfig"



config BLK_MQ_PCI

block/bdev.c

+40 −8
Original line number Diff line number Diff line
@@ -30,15 +30,20 @@ 
#include "../fs/internal.h"

#include "blk.h"



#define OPEN_EXCLUSIVE "VFS: Open an exclusive opened block device for write"

#define OPEN_FOR_EXCLUSIVE "VFS: Open a write opened block device exclusively"

#define bdev_write_mounted_opt(opt) (bdev_allow_write_mounted & (1 << BLKDEV_##opt))

/* Should we allow writing to mounted block devices? */

#define BLKDEV_ALLOW_WRITE_MOUNTED	0

/* Should we detect writing to part0 when partitions mounted  */

#define BLKDEV_DETECT_WRITING_PART0	1

/* Should we dump info when opening mounted block devices for write? */

#define BLKDEV_WRITE_MOUNTED_DUMP	2



static u8 bdev_allow_write_mounted =

	IS_ENABLED(CONFIG_BLK_DEV_WRITE_MOUNTED) << BLKDEV_ALLOW_WRITE_MOUNTED |

	IS_ENABLED(CONFIG_BLK_DEV_DETECT_WRITING_PART0) << BLKDEV_DETECT_WRITING_PART0;

	IS_ENABLED(CONFIG_BLK_DEV_DETECT_WRITING_PART0) << BLKDEV_DETECT_WRITING_PART0 |

	IS_ENABLED(CONFIG_BLK_DEV_WRITE_MOUNTED_DUMP) << BLKDEV_WRITE_MOUNTED_DUMP;



struct bdev_inode {

	struct block_device bdev;
@@ -740,11 +745,34 @@ void blkdev_put_no_open(struct block_device *bdev) 
	put_device(&bdev->bd_device);

}



static void blkdev_dump_conflict_opener(struct block_device *bdev, char *msg)

{

	char name[BDEVNAME_SIZE];

	struct task_struct *p = NULL;

	char comm_buf[TASK_COMM_LEN];

	pid_t p_pid;



	if (!bdev_write_mounted_opt(WRITE_MOUNTED_DUMP))

		return;

	rcu_read_lock();

	p = rcu_dereference(current->real_parent);

	task_lock(p);

	strncpy(comm_buf, p->comm, TASK_COMM_LEN);

	p_pid = p->pid;

	task_unlock(p);

	rcu_read_unlock();



	snprintf(name, sizeof(name), "%pg", bdev);

	pr_info_ratelimited("%s [%s]. current [%d %s]. parent [%d %s]\n",

			     msg, name,

			     current->pid, current->comm, p_pid, comm_buf);

}



static bool bdev_writes_blocked(struct block_device *bdev)

{

	if (bdev->bd_mounted)

		return true;

	if (bdev_opt(DETECT_WRITING_PART0))

	if (bdev_write_mounted_opt(DETECT_WRITING_PART0))

		return bdev_is_partition(bdev) ? bdev_whole(bdev)->bd_mounted :

						 bdev->bd_disk->mount_partitions;
@@ -769,7 +797,7 @@ static bool bdev_mount_blocked(struct block_device *bdev) 
{

	if (bdev->bd_writers)

		return true;

	if (bdev_opt(DETECT_WRITING_PART0))

	if (bdev_write_mounted_opt(DETECT_WRITING_PART0))

		return bdev_is_partition(bdev) ? bdev_whole(bdev)->bd_writers :

						 bdev->bd_disk->write_open_partitions;
@@ -792,14 +820,18 @@ static void bdev_unblock_mount(struct block_device *bdev) 


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

{

	if (bdev_write_mounted_opt(ALLOW_WRITE_MOUNTED))

	if (bdev_write_mounted_opt(ALLOW_WRITE_MOUNTED) &&

	    !bdev_write_mounted_opt(WRITE_MOUNTED_DUMP))

		return true;

	/* Writes blocked? */

	if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev))

		return false;

	if (mode & BLK_OPEN_RESTRICT_WRITES && bdev_mount_blocked(bdev))

		return false;

		blkdev_dump_conflict_opener(bdev, OPEN_EXCLUSIVE);

	else if (mode & BLK_OPEN_RESTRICT_WRITES && bdev_mount_blocked(bdev))

		blkdev_dump_conflict_opener(bdev, OPEN_FOR_EXCLUSIVE);

	else

		return true;



	return bdev_write_mounted_opt(ALLOW_WRITE_MOUNTED);

}



static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode)