diff options
| -rw-r--r-- | Documentation/device-mapper/dm-init.txt | 114 | ||||
| -rw-r--r-- | drivers/md/Kconfig | 12 | ||||
| -rw-r--r-- | drivers/md/Makefile | 4 | ||||
| -rw-r--r-- | drivers/md/dm-init.c | 303 | ||||
| -rw-r--r-- | drivers/md/dm-ioctl.c | 103 | ||||
| -rw-r--r-- | include/linux/device-mapper.h | 9 |
6 files changed, 545 insertions, 0 deletions
diff --git a/Documentation/device-mapper/dm-init.txt b/Documentation/device-mapper/dm-init.txt new file mode 100644 index 000000000000..8464ee7c01b8 --- /dev/null +++ b/Documentation/device-mapper/dm-init.txt @@ -0,0 +1,114 @@ +Early creation of mapped devices +==================================== + +It is possible to configure a device-mapper device to act as the root device for +your system in two ways. + +The first is to build an initial ramdisk which boots to a minimal userspace +which configures the device, then pivot_root(8) in to it. + +The second is to create one or more device-mappers using the module parameter +"dm-mod.create=" through the kernel boot command line argument. + +The format is specified as a string of data separated by commas and optionally +semi-colons, where: + - a comma is used to separate fields like name, uuid, flags and table + (specifies one device) + - a semi-colon is used to separate devices. + +So the format will look like this: + + dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+] + +Where, + <name> ::= The device name. + <uuid> ::= xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx | "" + <minor> ::= The device minor number | "" + <flags> ::= "ro" | "rw" + <table> ::= <start_sector> <num_sectors> <target_type> <target_args> + <target_type> ::= "verity" | "linear" | ... (see list below) + +The dm line should be equivalent to the one used by the dmsetup tool with the +--concise argument. + +Target types +============ + +Not all target types are available as there are serious risks in allowing +activation of certain DM targets without first using userspace tools to check +the validity of associated metadata. + + "cache": constrained, userspace should verify cache device + "crypt": allowed + "delay": allowed + "era": constrained, userspace should verify metadata device + "flakey": constrained, meant for test + "linear": allowed + "log-writes": constrained, userspace should verify metadata device + "mirror": constrained, userspace should verify main/mirror device + "raid": constrained, userspace should verify metadata device + "snapshot": constrained, userspace should verify src/dst device + "snapshot-origin": allowed + "snapshot-merge": constrained, userspace should verify src/dst device + "striped": allowed + "switch": constrained, userspace should verify dev path + "thin": constrained, requires dm target message from userspace + "thin-pool": constrained, requires dm target message from userspace + "verity": allowed + "writecache": constrained, userspace should verify cache device + "zero": constrained, not meant for rootfs + +If the target is not listed above, it is constrained by default (not tested). + +Examples +======== +An example of booting to a linear array made up of user-mode linux block +devices: + + dm-mod.create="lroot,,,rw, 0 4096 linear 98:16 0, 4096 4096 linear 98:32 0" root=/dev/dm-0 + +This will boot to a rw dm-linear target of 8192 sectors split across two block +devices identified by their major:minor numbers. After boot, udev will rename +this target to /dev/mapper/lroot (depending on the rules). No uuid was assigned. + +An example of multiple device-mappers, with the dm-mod.create="..." contents is shown here +split on multiple lines for readability: + + vroot,,,ro, + 0 1740800 verity 254:0 254:0 1740800 sha1 + 76e9be054b15884a9fa85973e9cb274c93afadb6 + 5b3549d54d6c7a3837b9b81ed72e49463a64c03680c47835bef94d768e5646fe; + vram,,,rw, + 0 32768 linear 1:0 0, + 32768 32768 linear 1:1 0 + +Other examples (per target): + +"crypt": + dm-crypt,,8,ro, + 0 1048576 crypt aes-xts-plain64 + babebabebabebabebabebabebabebabebabebabebabebabebabebabebabebabe 0 + /dev/sda 0 1 allow_discards + +"delay": + dm-delay,,4,ro,0 409600 delay /dev/sda1 0 500 + +"linear": + dm-linear,,,rw, + 0 32768 linear /dev/sda1 0, + 32768 1024000 linear /dev/sda2 0, + 1056768 204800 linear /dev/sda3 0, + 1261568 512000 linear /dev/sda4 0 + +"snapshot-origin": + dm-snap-orig,,4,ro,0 409600 snapshot-origin 8:2 + +"striped": + dm-striped,,4,ro,0 1638400 striped 4 4096 + /dev/sda1 0 /dev/sda2 0 /dev/sda3 0 /dev/sda4 0 + +"verity": + dm-verity,,4,ro, + 0 1638400 verity 1 8:1 8:2 4096 4096 204800 1 sha256 + fb1a5a0f00deb908d8b53cb270858975e76cf64105d412ce764225d53b8f3cfd + 51934789604d1b92399c52e7cb149d1b3a1b74bbbcb103b2a0aaacbed5c08584 diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index 3db222509e44..2557f198e175 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -436,6 +436,18 @@ config DM_DELAY If unsure, say N. +config DM_INIT + bool "DM \"dm-mod.create=\" parameter support" + depends on BLK_DEV_DM=y + ---help--- + Enable "dm-mod.create=" parameter to create mapped devices at init time. + This option is useful to allow mounting rootfs without requiring an + initramfs. + See Documentation/device-mapper/dm-init.txt for dm-mod.create="..." + format. + + If unsure, say N. + config DM_UEVENT bool "DM uevents" depends on BLK_DEV_DM diff --git a/drivers/md/Makefile b/drivers/md/Makefile index 822f4e8753bc..a52b703e588e 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -69,6 +69,10 @@ obj-$(CONFIG_DM_INTEGRITY) += dm-integrity.o obj-$(CONFIG_DM_ZONED) += dm-zoned.o obj-$(CONFIG_DM_WRITECACHE) += dm-writecache.o +ifeq ($(CONFIG_DM_INIT),y) +dm-mod-objs += dm-init.o +endif + ifeq ($(CONFIG_DM_UEVENT),y) dm-mod-objs += dm-uevent.o endif diff --git a/drivers/md/dm-init.c b/drivers/md/dm-init.c new file mode 100644 index 000000000000..b53f30f16b4d --- /dev/null +++ b/drivers/md/dm-init.c @@ -0,0 +1,303 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * dm-init.c + * Copyright (C) 2017 The Chromium OS Authors <chromium-os-dev@chromium.org> + * + * This file is released under the GPLv2. + */ + +#include <linux/ctype.h> +#include <linux/device.h> +#include <linux/device-mapper.h> +#include <linux/init.h> +#include <linux/list.h> +#include <linux/moduleparam.h> + +#define DM_MSG_PREFIX "init" +#define DM_MAX_DEVICES 256 +#define DM_MAX_TARGETS 256 +#define DM_MAX_STR_SIZE 4096 + +static char *create; + +/* + * Format: dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+] + * Table format: <start_sector> <num_sectors> <target_type> <target_args> + * + * See Documentation/device-mapper/dm-init.txt for dm-mod.create="..." format + * details. + */ + +struct dm_device { + struct dm_ioctl dmi; + struct dm_target_spec *table[DM_MAX_TARGETS]; + char *target_args_array[DM_MAX_TARGETS]; + struct list_head list; +}; + +const char *dm_allowed_targets[] __initconst = { + "crypt", + "delay", + "linear", + "snapshot-origin", + "striped", + "verity", +}; + +static int __init dm_verify_target_type(const char *target) +{ + unsigned int i; + + for (i = 0; i < ARRAY_SIZE(dm_allowed_targets); i++) { + if (!strcmp(dm_allowed_targets[i], target)) + return 0; + } + return -EINVAL; +} + +static void __init dm_setup_cleanup(struct list_head *devices) +{ + struct dm_device *dev, *tmp; + unsigned int i; + + list_for_each_entry_safe(dev, tmp, devices, list) { + list_del(&dev->list); + for (i = 0; i < dev->dmi.target_count; i++) { + kfree(dev->table[i]); + kfree(dev->target_args_array[i]); + } + kfree(dev); + } +} + +/** + * str_field_delimit - delimit a string based on a separator char. + * @str: the pointer to the string to delimit. + * @separator: char that delimits the field + * + * Find a @separator and replace it by '\0'. + * Remove leading and trailing spaces. + * Return the remainder string after the @separator. + */ +static char __init *str_field_delimit(char **str, char separator) +{ + char *s; + + /* TODO: add support for escaped characters */ + *str = skip_spaces(*str); + s = strchr(*str, separator); + /* Delimit the field and remove trailing spaces */ + if (s) + *s = '\0'; + *str = strim(*str); + return s ? ++s : NULL; +} + +/** + * dm_parse_table_entry - parse a table entry + * @dev: device to store the parsed information. + * @str: the pointer to a string with the format: + * <start_sector> <num_sectors> <target_type> <target_args>[, ...] + * + * Return the remainder string after the table entry, i.e, after the comma which + * delimits the entry or NULL if reached the end of the string. + */ +static char __init *dm_parse_table_entry(struct dm_device *dev, char *str) +{ + const unsigned int n = dev->dmi.target_count - 1; + struct dm_target_spec *sp; + unsigned int i; + /* fields: */ + char *field[4]; + char *next; + + field[0] = str; + /* Delimit first 3 fields that are separated by space */ + for (i = 0; i < ARRAY_SIZE(field) - 1; i++) { + field[i + 1] = str_field_delimit(&field[i], ' '); + if (!field[i + 1]) + return ERR_PTR(-EINVAL); + } + /* Delimit last field that can be terminated by comma */ + next = str_field_delimit(&field[i], ','); + + sp = kzalloc(sizeof(*sp), GFP_KERNEL); + if (!sp) + return ERR_PTR(-ENOMEM); + dev->table[n] = sp; + + /* start_sector */ + if (kstrtoull(field[0], 0, &sp->sector_start)) + return ERR_PTR(-EINVAL); + /* num_sector */ + if (kstrtoull(field[1], 0, &sp->length)) + return ERR_PTR(-EINVAL); + /* target_type */ + strscpy(sp->target_type, field[2], sizeof(sp->target_type)); + if (dm_verify_target_type(sp->target_type)) { + DMERR("invalid type \"%s\"", sp->target_type); + return ERR_PTR(-EINVAL); + } + /* target_args */ + dev->target_args_array[n] = kstrndup(field[3], GFP_KERNEL, + DM_MAX_STR_SIZE); + if (!dev->target_args_array[n]) + return ERR_PTR(-ENOMEM); + + return next; +} + +/** + * dm_parse_table - parse "dm-mod.create=" table field + * @dev: device to store the parsed information. + * @str: the pointer to a string with the format: + * <table>[,<table>+] + */ +static int __init dm_parse_table(struct dm_device *dev, char *str) +{ + char *table_entry = str; + + while (table_entry) { + DMDEBUG("parsing table \"%s\"", str); + if (++dev->dmi.target_count >= DM_MAX_TARGETS) { + DMERR("too many targets %u > %d", + dev->dmi.target_count, DM_MAX_TARGETS); + return -EINVAL; + } + table_entry = dm_parse_table_entry(dev, table_entry); + if (IS_ERR(table_entry)) { + DMERR("couldn't parse table"); + return PTR_ERR(table_entry); + } + } + + return 0; +} + +/** + * dm_parse_device_entry - parse a device entry + * @dev: device to store the parsed information. + * @str: the pointer to a string with the format: + * name,uuid,minor,flags,table[; ...] + * + * Return the remainder string after the table entry, i.e, after the semi-colon + * which delimits the entry or NULL if reached the end of the string. + */ +static char __init *dm_parse_device_entry(struct dm_device *dev, char *str) +{ + /* There are 5 fields: name,uuid,minor,flags,table; */ + char *field[5]; + unsigned int i; + char *next; + + field[0] = str; + /* Delimit first 4 fields that are separated by comma */ + for (i = 0; i < ARRAY_SIZE(field) - 1; i++) { + field[i+1] = str_field_delimit(&field[i], ','); + if (!field[i+1]) + return ERR_PTR(-EINVAL); + } + /* Delimit last field that can be delimited by semi-colon */ + next = str_field_delimit(&field[i], ';'); + + /* name */ + strscpy(dev->dmi.name, field[0], sizeof(dev->dmi.name)); + /* uuid */ + strscpy(dev->dmi.uuid, field[1], sizeof(dev->dmi.uuid)); + /* minor */ + if (strlen(field[2])) { + if (kstrtoull(field[2], 0, &dev->dmi.dev)) + return ERR_PTR(-EINVAL); + dev->dmi.flags |= DM_PERSISTENT_DEV_FLAG; + } + /* flags */ + if (!strcmp(field[3], "ro")) + dev->dmi.flags |= DM_READONLY_FLAG; + else if (strcmp(field[3], "rw")) + return ERR_PTR(-EINVAL); + /* table */ + if (dm_parse_table(dev, field[4])) + return ERR_PTR(-EINVAL); + + return next; +} + +/** + * dm_parse_devices - parse "dm-mod.create=" argument + * @devices: list of struct dm_device to store the parsed information. + * @str: the pointer to a string with the format: + * <device>[;<device>+] + */ +static int __init dm_parse_devices(struct list_head *devices, char *str) +{ + unsigned long ndev = 0; + struct dm_device *dev; + char *device = str; + + DMDEBUG("parsing \"%s\"", str); + while (device) { + dev = kzalloc(sizeof(*dev), GFP_KERNEL); + if (!dev) + return -ENOMEM; + list_add_tail(&dev->list, devices); + + if (++ndev >= DM_MAX_DEVICES) { + DMERR("too many targets %u > %d", + dev->dmi.target_count, DM_MAX_TARGETS); + return -EINVAL; + } + + device = dm_parse_device_entry(dev, device); + if (IS_ERR(device)) { + DMERR("couldn't parse device"); + return PTR_ERR(device); + } + } + + return 0; +} + +/** + * dm_init_init - parse "dm-mod.create=" argument and configure drivers + */ +static int __init dm_init_init(void) +{ + struct dm_device *dev; + LIST_HEAD(devices); + char *str; + int r; + + if (!create) + return 0; + + if (strlen(create) >= DM_MAX_STR_SIZE) { + DMERR("Argument is too big. Limit is %d\n", DM_MAX_STR_SIZE); + return -EINVAL; + } + str = kstrndup(create, GFP_KERNEL, DM_MAX_STR_SIZE); + if (!str) + return -ENOMEM; + + r = dm_parse_devices(&devices, str); + if (r) + goto out; + + DMINFO("waiting for all devices to be available before creating mapped devices\n"); + wait_for_device_probe(); + + list_for_each_entry(dev, &devices, list) { + if (dm_early_create(&dev->dmi, dev->table, + dev->target_args_array)) + break; + } +out: + kfree(str); + dm_setup_cleanup(&devices); + return r; +} + +late_initcall(dm_init_init); + +module_param(create, charp, 0); +MODULE_PARM_DESC(create, "Create a mapped device in early boot"); diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index f666778ad237..c740153b4e52 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -2018,3 +2018,106 @@ out: return r; } + + +/** + * dm_early_create - create a mapped device in early boot. + * + * @dmi: Contains main information of the device mapping to be created. + * @spec_array: array of pointers to struct dm_target_spec. Describes the + * mapping table of the device. + * @target_params_array: array of strings with the parameters to a specific + * target. + * + * Instead of having the struct dm_target_spec and the parameters for every + * target embedded at the end of struct dm_ioctl (as performed in a normal + * ioctl), pass them as arguments, so the caller doesn't need to serialize them. + * The size of the spec_array and target_params_array is given by + * @dmi->target_count. + * This function is supposed to be called in early boot, so locking mechanisms + * to protect against concurrent loads are not required. + */ +int __init dm_early_create(struct dm_ioctl *dmi, + struct dm_target_spec **spec_array, + char **target_params_array) +{ + int r, m = DM_ANY_MINOR; + struct dm_table *t, *old_map; + struct mapped_device *md; + unsigned int i; + + if (!dmi->target_count) + return -EINVAL; + + r = check_name(dmi->name); + if (r) + return r; + + if (dmi->flags & DM_PERSISTENT_DEV_FLAG) + m = MINOR(huge_decode_dev(dmi->dev)); + + /* alloc dm device */ + r = dm_create(m, &md); + if (r) + return r; + + /* hash insert */ + r = dm_hash_insert(dmi->name, *dmi->uuid ? dmi->uuid : NULL, md); + if (r) + goto err_destroy_dm; + + /* alloc table */ + r = dm_table_create(&t, get_mode(dmi), dmi->target_count, md); + if (r) + goto err_destroy_dm; + + /* add targets */ + for (i = 0; i < dmi->target_count; i++) { + r = dm_table_add_target(t, spec_array[i]->target_type, + (sector_t) spec_array[i]->sector_start, + (sector_t) spec_array[i]->length, + target_params_array[i]); + if (r) { + DMWARN("error adding target to table"); + goto err_destroy_table; + } + } + + /* finish table */ + r = dm_table_complete(t); + if (r) + goto err_destroy_table; + + md->type = dm_table_get_type(t); + /* setup md->queue to reflect md's type (may block) */ + r = dm_setup_md_queue(md, t); + if (r) { + DMWARN("unable to set up device queue for new table."); + goto err_destroy_table; + } + + /* Set new map */ + dm_suspend(md, 0); + old_map = dm_swap_table(md, t); + if (IS_ERR(old_map)) { + r = PTR_ERR(old_map); + goto err_destroy_table; + } + set_disk_ro(dm_disk(md), !!(dmi->flags & DM_READONLY_FLAG)); + + /* resume device */ + r = dm_resume(md); + if (r) + goto err_destroy_table; + + DMINFO("%s (%s) is ready", md->disk->disk_name, dmi->name); + dm_put(md); + return 0; + +err_destroy_table: + dm_table_destroy(t); +err_destroy_dm: + dm_put(md); + dm_destroy(md); + return r; +} diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 52e8709c6df0..b0672756d056 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -10,6 +10,7 @@ #include <linux/bio.h> #include <linux/blkdev.h> +#include <linux/dm-ioctl.h> #include <linux/math64.h> #include <linux/ratelimit.h> @@ -425,6 +426,14 @@ void dm_remap_zone_report(struct dm_target *ti, sector_t start, struct blk_zone *zones, unsigned int *nr_zones); union map_info *dm_get_rq_mapinfo(struct request *rq); +/* + * Device mapper functions to parse and create devices specified by the + * parameter "dm-mod.create=" + */ +int __init dm_early_create(struct dm_ioctl *dmi, + struct dm_target_spec **spec_array, + char **target_params_array); + struct queue_limits *dm_get_queue_limits(struct mapped_device *md); /* |