This change adds a dm= kernel parameter modelled after the md= parameter from do_mounts_md. It allows for simple device-mapper targets to be configured at boot time for use early in the boot process (as the root device or otherwise).
The format is as follows: dm="count name uuid|none ro|rw num-tables, table line 1, table line 2, ..." It relies on the ability to create a device mapper device programmatically and bind that device to the ioctl-style name/uuid. Based on work by Will Drewry and Paul Taysom. Signed-off-by: Kees Cook <keesc...@chromium.org> --- v5: resurrection, multiple devices, cleanups, error reporting improvements v4: https://patchwork.kernel.org/patch/104861/ --- Documentation/device-mapper/boot.txt | 64 ++++++ Documentation/kernel-parameters.txt | 4 + init/Makefile | 1 + init/do_mounts.c | 1 + init/do_mounts.h | 10 + init/do_mounts_dm.c | 433 +++++++++++++++++++++++++++++++++++ 6 files changed, 513 insertions(+) create mode 100644 Documentation/device-mapper/boot.txt create mode 100644 init/do_mounts_dm.c diff --git a/Documentation/device-mapper/boot.txt b/Documentation/device-mapper/boot.txt new file mode 100644 index 000000000000..9dd04b37b3b1 --- /dev/null +++ b/Documentation/device-mapper/boot.txt @@ -0,0 +1,64 @@ +Boot time 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 possible when the device-mapper and any targets are +compiled into the kernel (not a module), one or more device-mappers may +be created and used as the root device at boot time with the parameters +given with the boot line dm=... + +Multiple device-mappers can be stacked by specifying the number of +devices. A device can have multiple tables if the the number of tables +is specified. + + <dm> ::= <num-mappers> <device-mapper>+ + <device-mapper> ::= <head> "," <table>+ + <head> ::= <name> <uuid> <mode> [<num-tables>] + <table> ::= <start> <length> <type> <options> "," + <mode> ::= "ro" | "rw" + <uuid> ::= xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx | "none" + <type> ::= "verity" | "bootcache" | ... + +Each tables line may be as normal when using the dmsetup tool except for +two variations: +1. Any use of commas will be interpreted as a newline +2. Quotation marks cannot be escaped and cannot be used without + terminating the dm= argument. + +Unless renamed by udev, the device node created will be dm-0 as the +first minor number for the device-mapper is used during early creation. + +The <num-tables> field is optional and assumed to be 1. + +Examples +======== +An example of booting to a linear array made up of user-mode linux block +devices: + + dm="1 lroot none rw 2, 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="..." contents shown +here split on multiple lines for readability: + + 3 vboot none ro, + 0 1768000 bootcache + device=aa55b119-2a47-8c45-946a-5ac57765011f+1 + signature=76e9be054b15884a9fa85973e9cb274c93afadb6 + cache_start=1768000 max_blocks=100000 size_limit=23 max_trace=20000, + vroot none ro, + 0 1740800 verity payload=254:0 hashtree=254:0 hashstart=1740800 alg=sha1 + root_hexdigest=76e9be054b15884a9fa85973e9cb274c93afadb6 + salt=5b3549d54d6c7a3837b9b81ed72e49463a64c03680c47835bef94d768e5646fe, + vram none rw 2, + 0 32768 linear 1:0 0, + 32768 32768 linear 1:1 0, diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 9a53c929f017..ba3a49bc1229 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -56,6 +56,7 @@ parameter is applicable: BLACKFIN Blackfin architecture is enabled. CLK Common clock infrastructure is enabled. CMA Contiguous Memory Area support is enabled. + DM Device mapper support is enabled. DRM Direct Rendering Management support is enabled. DYNAMIC_DEBUG Build in debug messages and enable them at runtime EDD BIOS Enhanced Disk Drive Services (EDD) is enabled @@ -930,6 +931,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. dis_ucode_ldr [X86] Disable the microcode loader. + dm= [DM] Allows early creation of a device-mapper device. + See Documentation/device-mapper/boot.txt. + dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, this option disables the debugging code at boot. diff --git a/init/Makefile b/init/Makefile index 7bc47ee31c36..90410fd7b658 100644 --- a/init/Makefile +++ b/init/Makefile @@ -18,6 +18,7 @@ mounts-y := do_mounts.o mounts-$(CONFIG_BLK_DEV_RAM) += do_mounts_rd.o mounts-$(CONFIG_BLK_DEV_INITRD) += do_mounts_initrd.o mounts-$(CONFIG_BLK_DEV_MD) += do_mounts_md.o +mounts-$(CONFIG_BLK_DEV_DM) += do_mounts_dm.o # dependencies on generated files need to be listed explicitly $(obj)/version.o: include/generated/compile.h diff --git a/init/do_mounts.c b/init/do_mounts.c index dea5de95c2dd..1902a1c80831 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -566,6 +566,7 @@ void __init prepare_namespace(void) wait_for_device_probe(); md_run_setup(); + dm_run_setup(); if (saved_root_name[0]) { root_device_name = saved_root_name; diff --git a/init/do_mounts.h b/init/do_mounts.h index 067af1d9e8b6..ecb275782c03 100644 --- a/init/do_mounts.h +++ b/init/do_mounts.h @@ -74,3 +74,13 @@ void md_run_setup(void); static inline void md_run_setup(void) {} #endif + +#ifdef CONFIG_BLK_DEV_DM + +void dm_run_setup(void); + +#else + +static inline void dm_run_setup(void) {} + +#endif diff --git a/init/do_mounts_dm.c b/init/do_mounts_dm.c new file mode 100644 index 000000000000..331a0d551a34 --- /dev/null +++ b/init/do_mounts_dm.c @@ -0,0 +1,433 @@ +/* + * do_mounts_dm.c + * Copyright (C) 2010 The Chromium OS Authors <chromium-os-...@chromium.org> + * Based on do_mounts_md.c + * + * This file is released under the GPLv2. + */ +#include <linux/async.h> +#include <linux/ctype.h> +#include <linux/device-mapper.h> +#include <linux/fs.h> +#include <linux/string.h> +#include <linux/delay.h> + +#include "do_mounts.h" + +#define DM_MAX_DEVICES 256 +#define DM_MAX_TARGETS 256 +#define DM_MAX_NAME 32 +#define DM_MAX_UUID 129 +#define DM_NO_UUID "none" + +#define DM_MSG_PREFIX "init" +#define DMERR_PARSE(fmt, args...) \ + DMERR("failed to parse " fmt " for device %s<%lu>", args) + +/* Separators used for parsing the dm= argument. */ +#define DM_FIELD_SEP " " +#define DM_LINE_SEP "," +#define DM_ANY_SEP DM_FIELD_SEP DM_LINE_SEP + +/* See Documentation/device-mapper/boot.txt for dm="..." format details. */ + +struct dm_setup_table { + sector_t begin; + sector_t length; + char *type; + char *params; + /* simple singly linked list */ + struct dm_setup_table *next; +}; + +struct dm_device { + int minor; + int ro; + char name[DM_MAX_NAME]; + char uuid[DM_MAX_UUID]; + unsigned long num_tables; + struct dm_setup_table *table; + int table_count; + struct dm_device *next; +}; + +struct dm_option { + char *start; + char *next; + size_t len; + char delim; +}; + +static struct { + unsigned long num_devices; + char *str; +} dm_setup_args __initdata; + +static int dm_early_setup __initdata; + +static int __init get_dm_option(struct dm_option *opt, const char *accept) +{ + char *str = opt->next; + char *endp; + + if (!str) + return 0; + + str = skip_spaces(str); + opt->start = str; + endp = strpbrk(str, accept); + if (!endp) { /* act like strchrnul */ + opt->len = strlen(str); + endp = str + opt->len; + } else { + opt->len = endp - str; + } + opt->delim = *endp; + if (*endp == 0) { + /* Don't advance past the nul. */ + opt->next = endp; + } else { + opt->next = endp + 1; + } + return opt->len != 0; +} + +static int __init get_dm_option_u64(struct dm_option *opt, const char *sep, + unsigned long long *result) +{ + char buf[32]; + + if (!get_dm_option(opt, sep)) + return -EINVAL; + + strlcpy(buf, opt->start, min(sizeof(buf), opt->len + 1)); + return kstrtoull(buf, 0, result); +} + +static void __init dm_setup_cleanup(struct dm_device *devices) +{ + struct dm_device *dev = devices; + + while (dev) { + struct dm_device *old_dev = dev; + struct dm_setup_table *table = dev->table; + + while (table) { + struct dm_setup_table *old_table = table; + + kfree(table->type); + kfree(table->params); + table = table->next; + kfree(old_table); + dev->table_count--; + } + WARN_ON(dev->table_count); + dev = dev->next; + kfree(old_dev); + } +} + +static char * __init dm_parse_device(struct dm_device *dev, char *str, + unsigned long idx) +{ + struct dm_option opt; + size_t len; + unsigned long long num_tables; + + /* Grab the logical name of the device to be exported to udev */ + opt.next = str; + if (!get_dm_option(&opt, DM_FIELD_SEP)) { + DMERR_PARSE("name", "", idx); + goto parse_fail; + } + len = min(opt.len + 1, sizeof(dev->name)); + strlcpy(dev->name, opt.start, len); /* includes nul */ + + /* Grab the UUID value or "none" */ + if (!get_dm_option(&opt, DM_FIELD_SEP)) { + DMERR_PARSE("uuid", dev->name, idx); + goto parse_fail; + } + len = min(opt.len + 1, sizeof(dev->uuid)); + strlcpy(dev->uuid, opt.start, len); + + /* Determine if the table/device will be read only or read-write */ + get_dm_option(&opt, DM_ANY_SEP); + if (!strncmp("ro", opt.start, opt.len)) { + dev->ro = 1; + } else if (!strncmp("rw", opt.start, opt.len)) { + dev->ro = 0; + } else { + DMERR_PARSE("table mode", dev->name, idx); + goto parse_fail; + } + + /* Optional number field */ + if (opt.delim == DM_FIELD_SEP[0]) { + if (get_dm_option_u64(&opt, DM_LINE_SEP, &num_tables)) { + DMERR_PARSE("number of tables", dev->name, idx); + goto parse_fail; + } + } else { + num_tables = 1; + } + if (num_tables > DM_MAX_TARGETS) { + DMERR_PARSE("too many tables (%llu > %d)", num_tables, + DM_MAX_TARGETS, dev->name, idx); + } + dev->num_tables = num_tables; + + return opt.next; + +parse_fail: + return NULL; +} + +static char * __init dm_parse_tables(struct dm_device *dev, char *str, + unsigned long idx) +{ + struct dm_option opt; + struct dm_setup_table **table = &dev->table; + unsigned long num_tables = dev->num_tables; + unsigned long i; + unsigned long long value; + + /* + * Tables are defined as per the normal table format but with a + * comma as a newline separator. + */ + opt.next = str; + for (i = 0; i < num_tables; i++) { + *table = kzalloc(sizeof(struct dm_setup_table), GFP_KERNEL); + if (!*table) { + DMERR_PARSE("table %lu (out of memory)", i, dev->name, + idx); + goto parse_fail; + } + dev->table_count++; + + if (get_dm_option_u64(&opt, DM_FIELD_SEP, &value)) { + DMERR_PARSE("starting sector for table %lu", i, + dev->name, idx); + goto parse_fail; + } + (*table)->begin = value; + + if (get_dm_option_u64(&opt, DM_FIELD_SEP, &value)) { + DMERR_PARSE("length for table %lu", i, dev->name, idx); + goto parse_fail; + } + (*table)->length = value; + + if (get_dm_option(&opt, DM_FIELD_SEP)) + (*table)->type = kstrndup(opt.start, opt.len, + GFP_KERNEL); + if (!((*table)->type)) { + DMERR_PARSE("type for table %lu", i, dev->name, idx); + goto parse_fail; + } + if (get_dm_option(&opt, DM_LINE_SEP)) + (*table)->params = kstrndup(opt.start, opt.len, + GFP_KERNEL); + if (!((*table)->params)) { + DMERR_PARSE("params for table %lu", i, dev->name, idx); + goto parse_fail; + } + table = &((*table)->next); + } + DMDEBUG("tables parsed: %d", dev->table_count); + + return opt.next; + +parse_fail: + return NULL; +} + +static struct dm_device *dm_parse_args(void) +{ + struct dm_device *devices = NULL; + struct dm_device **tail = &devices; + struct dm_device *dev; + char *str = dm_setup_args.str; + unsigned long num_devices = dm_setup_args.num_devices; + unsigned long i; + + if (!str) + return NULL; + for (i = 0; i < num_devices; i++) { + dev = kzalloc(sizeof(*dev), GFP_KERNEL); + if (!dev) { + DMERR("failed to allocated memory for device %lu", i); + goto error; + } + *tail = dev; + tail = &dev->next; + /* + * devices are given minor numbers 0 - n-1 + * in the order they are found in the arg + * string. + */ + dev->minor = i; + str = dm_parse_device(dev, str, i); + if (!str) /* NULL indicates error in parsing, bail */ + goto error; + + str = dm_parse_tables(dev, str, i); + if (!str) + goto error; + } + return devices; +error: + dm_setup_cleanup(devices); + return NULL; +} + +/* + * Parse the command-line parameters given our kernel, but do not + * actually try to invoke the DM device now; that is handled by + * dm_setup_drives after the low-level disk drivers have initialised. + * dm format is described at the top of the file. + * + * Because dm minor numbers are assigned in assending order starting with 0, + * You can assume the first device is /dev/dm-0, the next device is /dev/dm-1, + * and so forth. + */ +static int __init dm_setup(char *str) +{ + struct dm_option opt; + unsigned long long num_devices; + + if (!str) { + DMERR("setup str is NULL"); + goto parse_fail; + } + + DMDEBUG("Want to parse \"%s\"", str); + opt.next = str; + if (get_dm_option_u64(&opt, DM_FIELD_SEP, &num_devices)) + goto parse_fail; + str = opt.next; + if (num_devices > DM_MAX_DEVICES) { + DMERR("too many devices %llu > %d", num_devices, + DM_MAX_DEVICES); + } + dm_setup_args.num_devices = num_devices; + dm_setup_args.str = str; + + DMINFO("will configure %lu device%s", dm_setup_args.num_devices, + dm_setup_args.num_devices == 1 ? "" : "s"); + dm_early_setup = 1; + return 1; + +parse_fail: + DMWARN("Invalid arguments supplied to dm=."); + return 0; +} + +static void __init dm_setup_drives(void) +{ + struct mapped_device *md = NULL; + struct dm_table *tables = NULL; + struct dm_setup_table *table; + struct dm_device *dev; + char *uuid; + fmode_t fmode = FMODE_READ; + struct dm_device *devices; + + devices = dm_parse_args(); + + for (dev = devices; dev; dev = dev->next) { + if (dm_create(dev->minor, &md)) { + DMERR("failed to create device %s", dev->name); + goto fail; + } + DMDEBUG("created device '%s'", dm_device_name(md)); + + /* + * In addition to flagging the table below, the disk must be + * set explicitly ro/rw. + */ + set_disk_ro(dm_disk(md), dev->ro); + + if (!dev->ro) + fmode |= FMODE_WRITE; + if (dm_table_create(&tables, fmode, dev->table_count, md)) { + DMERR("failed to create device %s tables", dev->name); + goto fail_put; + } + for (table = dev->table; table; table = table->next) { + DMINFO("device %s adding table '%llu %llu %s %s'", + dev->name, + (unsigned long long) table->begin, + (unsigned long long) table->length, + table->type, table->params); + if (dm_table_add_target(tables, table->type, + table->begin, + table->length, + table->params)) { + DMERR("failed to add table to device %s", + dev->name); + goto fail_put; + } + } + dm_lock_md_type(md); + if (dm_table_complete(tables)) { + DMERR("failed to complete device %s tables", + dev->name); + dm_unlock_md_type(md); + goto fail_put; + } + dm_unlock_md_type(md); + + /* Suspend the device so that we can bind it to the tables. */ + if (dm_suspend(md, 0)) { + DMERR("failed to suspend device %s pre-bind", + dev->name); + goto fail_put; + } + + /* + * Bind the tables to the device. This is the only way + * to associate md->map with the tables and set the disk + * capacity directly. + */ + if (dm_swap_table(md, tables)) { /* should return NULL. */ + DMERR("failed to bind device %s to tables", + dev->name); + goto fail_put; + } + + /* Finally, resume and the device should be ready. */ + if (dm_resume(md)) { + DMERR("failed to resume device %s", dev->name); + goto fail_put; + } + + /* Export the dm device via the ioctl interface */ + if (!strcmp(DM_NO_UUID, dev->uuid)) + uuid = NULL; + if (dm_ioctl_export(md, dev->name, uuid)) { + DMERR("failed to export device %s", dev->name); + goto fail_put; + } + DMINFO("dm-%d (%s) is ready", dev->minor, dev->name); + } + dm_setup_cleanup(devices); + return; + +fail_put: + dm_put(md); +fail: + DMERR("starting dm-%d (%s) failed", dev->minor, dev->name); + dm_setup_cleanup(devices); +} + +__setup("dm=", dm_setup); + +void __init dm_run_setup(void) +{ + if (!dm_early_setup) + return; + DMINFO("attempting early device configuration."); + dm_setup_drives(); +} -- 2.6.3
