A message can be passed to device mapper to prohibit open on a certain mapped device. This makes possible to disallow userspace access to raw swapped data if the system uses device mapper to encrypt it at rest.
Signed-off-by: Daniil Lunev <[email protected]> --- drivers/md/dm-core.h | 1 + drivers/md/dm-ioctl.c | 10 ++++++++++ drivers/md/dm.c | 12 ++++++++++++ drivers/md/dm.h | 10 ++++++++++ include/uapi/linux/dm-ioctl.h | 5 +++++ 5 files changed, 38 insertions(+) diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h index 4277853c75351..37529b605b7c4 100644 --- a/drivers/md/dm-core.h +++ b/drivers/md/dm-core.h @@ -140,6 +140,7 @@ struct mapped_device { #define DMF_SUSPENDED_INTERNALLY 7 #define DMF_POST_SUSPENDING 8 #define DMF_EMULATE_ZONE_APPEND 9 +#define DMF_DISALLOW_OPEN 10 void disable_discard(struct mapped_device *md); void disable_write_zeroes(struct mapped_device *md); diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 87310fceb0d86..e35d560aa2ff3 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -815,6 +815,9 @@ static void __dev_status(struct mapped_device *md, struct dm_ioctl *param) if (dm_test_deferred_remove_flag(md)) param->flags |= DM_DEFERRED_REMOVE; + if (dm_test_disallow_open_flag(md)) + param->flags |= DM_DISALLOWED_OPEN; + param->dev = huge_encode_dev(disk_devt(disk)); /* @@ -1656,6 +1659,13 @@ static int message_for_md(struct mapped_device *md, unsigned argc, char **argv, } return dm_cancel_deferred_remove(md); } + if (!strcasecmp(argv[0], "@disallow_open")) { + if (argc != 1) { + DMERR("Invalid arguments for @disallow_open"); + return -EINVAL; + } + return dm_disallow_open(md); + } r = dm_stats_message(md, argc, argv, result, maxlen); if (r < 2) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 82957bd460e89..3e53d1bd40f0c 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -327,6 +327,7 @@ static int dm_blk_open(struct block_device *bdev, fmode_t mode) goto out; if (test_bit(DMF_FREEING, &md->flags) || + test_bit(DMF_DISALLOW_OPEN, &md->flags) || dm_deleting_md(md)) { md = NULL; goto out; @@ -403,6 +404,12 @@ int dm_cancel_deferred_remove(struct mapped_device *md) return r; } +int dm_disallow_open(struct mapped_device *md) +{ + set_bit(DMF_DISALLOW_OPEN, &md->flags); + return 0; +} + static void do_deferred_remove(struct work_struct *w) { dm_deferred_remove(); @@ -2883,6 +2890,11 @@ int dm_test_deferred_remove_flag(struct mapped_device *md) return test_bit(DMF_DEFERRED_REMOVE, &md->flags); } +int dm_test_disallow_open_flag(struct mapped_device *md) +{ + return test_bit(DMF_DISALLOW_OPEN, &md->flags); +} + int dm_suspended(struct dm_target *ti) { return dm_suspended_md(ti->table->md); diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 9013dc1a7b002..da27f9dfe1413 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -163,6 +163,16 @@ int dm_test_deferred_remove_flag(struct mapped_device *md); */ void dm_deferred_remove(void); +/* + * Test if the device is openable. + */ +int dm_test_disallow_open_flag(struct mapped_device *md); + +/* + * Prevent new open request on the device. + */ +int dm_disallow_open(struct mapped_device *md); + /* * The device-mapper can be driven through one of two interfaces; * ioctl or filesystem, depending which patch you have applied. diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h index 2e9550fef90fa..3b4d12d09c005 100644 --- a/include/uapi/linux/dm-ioctl.h +++ b/include/uapi/linux/dm-ioctl.h @@ -382,4 +382,9 @@ enum { */ #define DM_IMA_MEASUREMENT_FLAG (1 << 19) /* In */ +/* + * If set, the device can not be opened. + */ +#define DM_DISALLOWED_OPEN (1 << 20) /* Out */ + #endif /* _LINUX_DM_IOCTL_H */ -- 2.31.0 -- dm-devel mailing list [email protected] https://listman.redhat.com/mailman/listinfo/dm-devel
