[PATCH OLK-6.6 v4 0/5] block: Add config to show info about opening a mounted device for write
Both writing a mounted device and writing part0 while mounting a partition will provide a prompt message. v1->v2: 1) Replace BLK_DEV_DUMPINFO with BLK_DEV_WRITE_MOUNTED_QUIET, which is logically opposite; 2) Make BLK_DEV_WRITE_MOUNTED_QUIET dependent on BLK_DEV_WRITE_MOUNTED, and decide whether to set bd_writers by BLK_DEV_WRITE_MOUNTED_QUIET; 3) Move bdev_dump_info() into bdev_may_open(); 4) Add the cmdline interface to control whether to show info; 5) Pass the state of "writes blocked" to part0 when mounting a partition. v2->v3: Add restriction for modifying bd_writers. v3->v4: 1) Count bd_writers regardless of whether bdev_allow_write_mounted is set; 2) Expand the meaning of bdev_allow_write_mounted; 3) Add config option to detect writing to part0 while partitions mounted; 4) Add bd_mounters to record the number of times that part0 or partition is mounted; 5) Show info about opening a lower device for write while upper-layers mounted. Li Lingfeng (5): block: Count bd_writers regardless of whether bdev_allow_write_mounted is set block: Expand the meaning of bdev_allow_write_mounted block: Add config option to detect writing to part0 while partitions mounted block: Add config option to show info about opening a mounted device for write block: Show info about opening a lower device for write while upper-layers mounted block/Kconfig | 19 ++++++++ block/bdev.c | 100 +++++++++++++++++++++++++++++++++----- include/linux/blk_types.h | 1 + 3 files changed, 107 insertions(+), 13 deletions(-) -- 2.31.1
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8S3GW CVE: NA --------------------------- The count of bd_writers can have other uses and it doesn't block writes when bdev_allow_write_mounted is not set, so delete the restriction for counting it. Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- block/bdev.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/block/bdev.c b/block/bdev.c index dd39c26c44ad..4e36cb6fd887 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -762,9 +762,6 @@ static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode) static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode) { - if (bdev_allow_write_mounted) - return; - /* Claim exclusive or shared write access. */ if (mode & BLK_OPEN_RESTRICT_WRITES) bdev_block_writes(bdev); @@ -774,9 +771,6 @@ static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode) static void bdev_yield_write_access(struct block_device *bdev, blk_mode_t mode) { - if (bdev_allow_write_mounted) - return; - /* Yield exclusive or shared write access. */ if (mode & BLK_OPEN_RESTRICT_WRITES) bdev_unblock_writes(bdev); -- 2.31.1
Hi, 在 2024/01/08 16:55, Li Lingfeng 写道:
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8S3GW CVE: NA
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The count of bd_writers can have other uses and it doesn't block writes when bdev_allow_write_mounted is not set, so delete the restriction for counting it.
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- block/bdev.c | 6 ------ 1 file changed, 6 deletions(-)
diff --git a/block/bdev.c b/block/bdev.c index dd39c26c44ad..4e36cb6fd887 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -762,9 +762,6 @@ static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode)
static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode) { - if (bdev_allow_write_mounted) - return; - /* Claim exclusive or shared write access. */ if (mode & BLK_OPEN_RESTRICT_WRITES) bdev_block_writes(bdev); @@ -774,9 +771,6 @@ static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode)
static void bdev_yield_write_access(struct block_device *bdev, blk_mode_t mode) { - if (bdev_allow_write_mounted) - return; - /* Yield exclusive or shared write access. */ if (mode & BLK_OPEN_RESTRICT_WRITES) bdev_unblock_writes(bdev);
这种写法会有并发问题， 需要将bd_mounters的计数从第三个补丁挪到第一个补丁
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8S3GW CVE: NA --------------------------- For bdev_allow_write_mounted, there will be more subdivided scenarios and different bits of it will be used to indicate different scenarios, so expand it now. Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- block/bdev.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/block/bdev.c b/block/bdev.c index 4e36cb6fd887..e8a0c511492d 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -31,7 +31,10 @@ #include "blk.h" /* Should we allow writing to mounted block devices? */ -static bool bdev_allow_write_mounted = IS_ENABLED(CONFIG_BLK_DEV_WRITE_MOUNTED); +#define BLKDEV_ALLOW_WRITE_MOUNTED 0 + +static u8 bdev_allow_write_mounted = + IS_ENABLED(CONFIG_BLK_DEV_WRITE_MOUNTED) << BLKDEV_ALLOW_WRITE_MOUNTED; struct bdev_inode { struct block_device bdev; @@ -750,7 +753,7 @@ static void bdev_unblock_writes(struct block_device *bdev) static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode) { - if (bdev_allow_write_mounted) + if (bdev_allow_write_mounted & (1 << BLKDEV_ALLOW_WRITE_MOUNTED)) return true; /* Writes blocked? */ if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev)) @@ -1129,7 +1132,7 @@ void bdev_statx_dioalign(struct inode *inode, struct kstat *stat) static int __init setup_bdev_allow_write_mounted(char *str) { - if (kstrtobool(str, &bdev_allow_write_mounted)) + if (kstrtou8(str, 0, &bdev_allow_write_mounted)) pr_warn("Invalid option string for bdev_allow_write_mounted:" " '%s'\n", str); return 1; -- 2.31.1
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8S3GW CVE: NA --------------------------- When a partition of a block device is mounted, opening the entire block device for write operations may also damage the file system. Identify this situation. Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- block/Kconfig | 10 ++++++++++ block/bdev.c | 26 +++++++++++++++++++++----- include/linux/blk_types.h | 1 + 3 files changed, 32 insertions(+), 5 deletions(-) diff --git a/block/Kconfig b/block/Kconfig index 03b53a50939f..05fdd81a708f 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -239,6 +239,16 @@ config BLK_INLINE_ENCRYPTION_FALLBACK by falling back to the kernel crypto API when inline encryption hardware is not present. +config BLK_DEV_DETECT_WRITING_PART0 + bool "Detect writing to part0 when partitions mounted" + default n + help + When partitions of a block device are mounted, writing to part0's + buffer cache is likely going to cause filesystem corruption on + each partition. + As a supplement to BLK_DEV_WRITE_MOUNTED(_QUIET), enabling this + to detect the scenario above. + source "block/partitions/Kconfig" config BLK_MQ_PCI diff --git a/block/bdev.c b/block/bdev.c index e8a0c511492d..4b0e6c49a9e7 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -32,9 +32,12 @@ /* 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 static u8 bdev_allow_write_mounted = - IS_ENABLED(CONFIG_BLK_DEV_WRITE_MOUNTED) << BLKDEV_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; struct bdev_inode { struct block_device bdev; @@ -738,17 +741,30 @@ void blkdev_put_no_open(struct block_device *bdev) static bool bdev_writes_blocked(struct block_device *bdev) { - return bdev->bd_writers == -1; + return !!bdev->bd_mounters; } static void bdev_block_writes(struct block_device *bdev) { - bdev->bd_writers = -1; + bdev->bd_mounters++; + if (bdev_is_partition(bdev) && + bdev_allow_write_mounted & (1 << BLKDEV_DETECT_WRITING_PART0)) + bdev_whole(bdev)->bd_mounters++; } static void bdev_unblock_writes(struct block_device *bdev) { - bdev->bd_writers = 0; + bdev->bd_mounters--; + if (bdev_is_partition(bdev) && + bdev_allow_write_mounted & (1 << BLKDEV_DETECT_WRITING_PART0)) + bdev_whole(bdev)->bd_mounters--; +} + +static bool bdev_mount_blocked(struct block_device *bdev) +{ + if (bdev_allow_write_mounted & (1 << BLKDEV_DETECT_WRITING_PART0)) + return bdev->bd_writers > 0 || bdev_whole(bdev)->bd_writers > 0; + return bdev->bd_writers > 0; } static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode) @@ -758,7 +774,7 @@ static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode) /* Writes blocked? */ if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev)) return false; - if (mode & BLK_OPEN_RESTRICT_WRITES && bdev->bd_writers > 0) + if (mode & BLK_OPEN_RESTRICT_WRITES && bdev_mount_blocked(bdev)) return false; return true; } diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 262ae789726b..0e1e429d3f74 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -70,6 +70,7 @@ struct block_device { bool bd_make_it_fail; #endif int bd_writers; + int bd_mounters; /* * keep this out-of-line as it's both big and not needed in the fast * path -- 2.31.1
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: Li Lingfeng <lilingfeng3@huawei.com> --- block/Kconfig | 9 +++++++++ block/bdev.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 63 insertions(+), 2 deletions(-) diff --git a/block/Kconfig b/block/Kconfig index 05fdd81a708f..29065fb2860b 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -249,6 +249,15 @@ config BLK_DEV_DETECT_WRITING_PART0 As a supplement to BLK_DEV_WRITE_MOUNTED(_QUIET), enabling this to detect the scenario above. +config BLK_DEV_WRITE_MOUNTED_QUIET + bool "Keep quiet when detecting conflict of opening block device" + default y + depends on BLK_DEV_WRITE_MOUNTED + help + While writing to mounted block devices is allowed, disabling 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 diff --git a/block/bdev.c b/block/bdev.c index 4b0e6c49a9e7..720b01b4cb45 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -34,10 +34,13 @@ #define BLKDEV_ALLOW_WRITE_MOUNTED 0 /* Should we detect writing to part0 when partitions mounted */ #define BLKDEV_DETECT_WRITING_PART0 1 +/* Should we keep quiet when opening mounted block devices for write? */ +#define BLKDEV_WRITE_MOUNTED_QUIET 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_QUIET) << BLKDEV_WRITE_MOUNTED_QUIET; struct bdev_inode { struct block_device bdev; @@ -739,6 +742,27 @@ 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; + + 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) { return !!bdev->bd_mounters; @@ -767,10 +791,25 @@ static bool bdev_mount_blocked(struct block_device *bdev) return bdev->bd_writers > 0; } +static void bdev_dump_info(struct block_device *bdev, blk_mode_t mode) +{ + if (bdev_allow_write_mounted & (1 << BLKDEV_WRITE_MOUNTED_QUIET)) + return; + + if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev)) + blkdev_dump_conflict_opener(bdev, "VFS: Open an exclusive opened " + "block device for write"); + else if (mode & BLK_OPEN_RESTRICT_WRITES && bdev_mount_blocked(bdev)) + blkdev_dump_conflict_opener(bdev, "VFS: Open a write opened " + "block device exclusively"); +} + static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode) { - if (bdev_allow_write_mounted & (1 << BLKDEV_ALLOW_WRITE_MOUNTED)) + if (bdev_allow_write_mounted & (1 << BLKDEV_ALLOW_WRITE_MOUNTED)) { + bdev_dump_info(bdev, mode); return true; + } /* Writes blocked? */ if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev)) return false; @@ -1151,6 +1190,19 @@ static int __init setup_bdev_allow_write_mounted(char *str) if (kstrtou8(str, 0, &bdev_allow_write_mounted)) pr_warn("Invalid option string for bdev_allow_write_mounted:" " '%s'\n", str); + /* + * It's meaningless to set BLKDEV_WRITE_MOUNTED_QUIET if + * BLKDEV_ALLOW_WRITE_MOUNTED is not set. + */ + if (!(bdev_allow_write_mounted & (1 << BLKDEV_ALLOW_WRITE_MOUNTED))) { + if (bdev_allow_write_mounted & (1 << BLKDEV_WRITE_MOUNTED_QUIET)) { + pr_warn("Invalid value for bdev_allow_write_mounted:" + " '%d', it should be set as 0/1/2/3/5/7\n", + bdev_allow_write_mounted); + bdev_allow_write_mounted &= ~(1 << BLKDEV_WRITE_MOUNTED_QUIET); + } + } + return 1; } __setup("bdev_allow_write_mounted=", setup_bdev_allow_write_mounted); -- 2.31.1
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8S3GW CVE: NA --------------------------- Filesystem on logic devices may be corrupted when writing to a block device which is used to create logic devices, so show info to indicate this risk behavior. Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- block/bdev.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/block/bdev.c b/block/bdev.c index 720b01b4cb45..0db7e4ee7a00 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -768,6 +768,14 @@ static bool bdev_writes_blocked(struct block_device *bdev) return !!bdev->bd_mounters; } +static bool bdev_lower_device_writes_blocked(struct block_device *bdev) +{ + if (bdev_allow_write_mounted & (1 << BLKDEV_DETECT_WRITING_PART0)) + return !!bdev->bd_holder; + else + return !!bdev->bd_holder && bdev->bd_holder != bd_may_claim; +} + static void bdev_block_writes(struct block_device *bdev) { bdev->bd_mounters++; @@ -796,7 +804,8 @@ static void bdev_dump_info(struct block_device *bdev, blk_mode_t mode) if (bdev_allow_write_mounted & (1 << BLKDEV_WRITE_MOUNTED_QUIET)) return; - if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev)) + if (mode & BLK_OPEN_WRITE && (bdev_writes_blocked(bdev) || + bdev_lower_device_writes_blocked(bdev))) blkdev_dump_conflict_opener(bdev, "VFS: Open an exclusive opened " "block device for write"); else if (mode & BLK_OPEN_RESTRICT_WRITES && bdev_mount_blocked(bdev)) -- 2.31.1
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Li Lingfeng -
Yu Kuai