From: Will Drewry <wad@xxxxxxxxxxxx> Add a dm= kernel parameter modeled after the md= parameter from do_mounts_md. It allows for device-mapper targets to be configured at boot time for use early in the boot process (as the root device or otherwise). Signed-off-by: Will Drewry <wad@xxxxxxxxxxxx> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> [rework to use dm_ioctl calls] Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx> --- Documentation/admin-guide/kernel-parameters.rst | 1 + Documentation/admin-guide/kernel-parameters.txt | 3 + Documentation/device-mapper/dm-boot.txt | 65 ++++ init/Makefile | 1 + init/do_mounts.c | 1 + init/do_mounts.h | 10 + init/do_mounts_dm.c | 459 ++++++++++++++++++++++++ 7 files changed, 540 insertions(+) create mode 100644 Documentation/device-mapper/dm-boot.txt create mode 100644 init/do_mounts_dm.c diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst index d76ab39..5301f45 100644 --- a/Documentation/admin-guide/kernel-parameters.rst +++ b/Documentation/admin-guide/kernel-parameters.rst @@ -92,6 +92,7 @@ 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 diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f85bfe0..0ea65c2 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -829,6 +829,9 @@ 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/Documentation/device-mapper/dm-boot.txt b/Documentation/device-mapper/dm-boot.txt new file mode 100644 index 0000000..50f08ec --- /dev/null +++ b/Documentation/device-mapper/dm-boot.txt @@ -0,0 +1,65 @@ +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=... + +The format is specified as a simple 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=<dev_name>,<uuid>,<flags>,<table>[,<table>+][;<dev_name>,<uuid>,<flags>,<table>[,<table>+]]+ + +Where, + <dev_name> ::= The device name. + <uuid> ::= xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx | "" + <flags> ::= "ro" | "rw" + <table> ::= <start> <length> <type> <options> + <type> ::= "verity" | "bootcache" | ... + +The dm line may be as normal when using the dmsetup tool when using the +--bootformat 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. + +Examples +======== +An example of booting to a linear array made up of user-mode linux block +devices: + + dm="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="..." contents shown +here split on multiple lines for readability: + + vboot,,ro, + 0 1768000 bootcache + aa55b119-2a47-8c45-946a-5ac57765011f+1 + 76e9be054b15884a9fa85973e9cb274c93afadb6 + 1768000 100000 23 20000; + 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 diff --git a/init/Makefile b/init/Makefile index c4fb455..30424d7 100644 --- a/init/Makefile +++ b/init/Makefile @@ -20,6 +20,7 @@ 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 c2de510..8b9182b 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 282d65b..4e71c29 100644 --- a/init/do_mounts.h +++ b/init/do_mounts.h @@ -60,3 +60,13 @@ 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 0000000..87c4300 --- /dev/null +++ b/init/do_mounts_dm.c @@ -0,0 +1,459 @@ +/* + * do_mounts_dm.c + * Copyright (C) 2017 The Chromium OS Authors <chromium-os-dev@xxxxxxxxxxxx> + * 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_NAME 32 +#define DM_MAX_UUID 129 + +#define DM_MSG_PREFIX "init" + +#define is_even(a) (((a) & 1) == 0) + +/* See Documentation/device-mapper/dm-boot.txt for dm="..." format details. */ + +struct target { + sector_t start; + sector_t length; + char *type; + char *params; + /* simple singly linked list */ + struct target *next; +}; + +struct dm_device { + int minor; + int ro; + char name[DM_MAX_NAME]; + char uuid[DM_MAX_UUID]; + struct target *table; + int table_count; + /* simple singly linked list */ + struct dm_device *next; +}; + +static struct { + unsigned long num_devices; + char *str; +} dm_setup_args __initdata; + +static int dm_early_setup __initdata; + +static void __init *_align(void *ptr, unsigned int a) +{ + register unsigned long agn = --a; + + return (void *) (((unsigned long) ptr + agn) & ~agn); +} + +/* + * Unescape characters in situ, it replaces all occurrences of "\c" + * with 'c'. This is normally used to unescape colons and semi-colons used + * in boot format. + */ +static char __init *_unescape_char(char *str, const char c) +{ + int i = 0, j = 0; + int len = strlen(str); + + if (len < 2) + return str; + + while (j < len - 1) { + if (str[j] == '\\' && str[j + 1] == c) { + j = j + 2; + str[i++] = c; + continue; + } + str[i++] = str[j++]; + } + + if (j == len - 1) + str[i++] = str[j]; + + str[i] = '\0'; + + return str; +} + +static void __init dm_setup_cleanup(struct dm_device *devices) +{ + struct dm_device *dev = devices; + + while (dev) { + struct dm_device *old_dev = dev; + struct target *table = dev->table; + + while (table) { + struct target *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); + } +} + +/* + * Splits a string into tokens ignoring escaped chars + * + * Updates @s to point after the token, ready for the next call. + * + * @str: The string to be searched + * @c: The character to search for + * + * Returns: + * The string found or NULL. + */ +static char __init *dm_find_unescaped_char(char **str, const char c) +{ + char *s = *str; + char *p = strchr(*str, c); + + /* loop through all the characters */ + while (p != NULL) { + /* scan backwards through preceding escapes */ + char *q = p; + + while (q > s && *(q - 1) == '\\') + --q; + /* even number of escapes so c is a token */ + if (is_even(p - q)) { + *p = '\0'; + *str = p + 1; + return s; + } + /* else odd escapes so c is escaped, keep going */ + p = strchr(p + 1, c); + } + + if (strlen(*str)) { + *str += strlen(*str); + return s; + } + + return NULL; +} + +static struct target __init *dm_parse_table(struct dm_device *dev, char *str) +{ + char type[DM_MAX_TYPE_NAME], *ptr; + struct target *table; + int n; + + /* trim trailing space */ + for (ptr = str + strlen(str) - 1; ptr >= str; ptr--) + if (!isspace((int) *ptr)) + break; + ptr++; + *ptr = '\0'; + + /* trim leading space */ + for (ptr = str; *ptr && isspace((int) *ptr); ptr++) + ; + + if (!*ptr) + return NULL; + + table = kzalloc(sizeof(struct target), GFP_KERNEL); + if (!table) + return NULL; + + if (sscanf(ptr, "%llu %llu %s %n", &table->start, &table->length, + type, &n) < 3) { + DMERR("invalid format of table \"%s\"", str); + goto parse_fail; + } + + table->type = kstrndup(type, strlen(type), GFP_KERNEL); + if (!table->type) { + DMERR("invalid type of table"); + goto parse_fail; + } + + ptr += n; + table->params = kstrndup(ptr, strlen(ptr), GFP_KERNEL); + if (!table->params) { + DMERR("invalid params for table"); + goto parse_fail; + } + + dev->table_count++; + + return table; + +parse_fail: + kfree(table); + return NULL; +} + +static int __init dm_parse_device(struct dm_device *dev, char *dev_info) +{ + int field = 0; + char *str = dev_info, *ptr = dev_info; + struct target *table; + struct target **tail = &dev->table; + + while ((str = dm_find_unescaped_char(&ptr, ',')) != NULL) { + str = _unescape_char(str, ','); + switch (field) { + case 0: /* set device name */ + strncpy(dev->name, str, strlen(str)); + break; + case 1: /* set uuid if any */ + strncpy(dev->uuid, str, strlen(str)); + break; + case 2: + /* set as read-only if flags = "ro" | "" */ + if (!strncmp(str, "ro", strlen(str)) || !strlen(str)) + dev->ro = 1; + else if (!strncmp(str, "rw", strlen(str))) + dev->ro = 0; + else + return -EINVAL; + break; + default: + table = dm_parse_table(dev, str); + if (!table) + goto parse_fail; + + *tail = table; + tail = &table->next; + + break; + } + field++; + } + + if (field < 4) + goto parse_fail; + + return 0; + +parse_fail: + return -EINVAL; +} + +static struct dm_device __init *dm_parse_args(void) +{ + struct dm_device *devices = NULL; + struct dm_device **tail = &devices; + struct dm_device *dev; + char *dev_info, *str = dm_setup_args.str; + + while ((dev_info = dm_find_unescaped_char(&str, ';')) != NULL) { + dev_info = _unescape_char(dev_info, ';'); + dev = kzalloc(sizeof(*dev), GFP_KERNEL); + if (!dev) + goto error; + + if (dm_parse_device(dev, dev_info)) + 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 = dm_setup_args.num_devices++; + + if (dm_setup_args.num_devices > DM_MAX_DEVICES) { + DMERR("too many devices %lu > %d", + dm_setup_args.num_devices, DM_MAX_DEVICES); + 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 ascending 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) +{ + if (!str) { + DMERR("Invalid arguments supplied to dm=."); + return 0; + } + + DMDEBUG("Want to parse \"%s\"", str); + + dm_setup_args.num_devices = 0; + dm_setup_args.str = str; + + dm_early_setup = 1; + + return 1; +} + +static char __init *dm_add_target(struct target *table, char *out, char *end) +{ + char *out_sp = out; + struct dm_target_spec sp; + size_t sp_size = sizeof(struct dm_target_spec); + int len; + char *pt; + + if (strlen(table->type) >= sizeof(sp.target_type)) { + DMERR("target type name %s is too long.", table->type); + return NULL; + } + + sp.status = 0; + sp.sector_start = table->start; + sp.length = table->length; + strncpy(sp.target_type, table->type, sizeof(sp.target_type) - 1); + sp.target_type[sizeof(sp.target_type) - 1] = '\0'; + + out += sp_size; + pt = table->params; + len = strlen(table->params); + + if ((out >= end) || (out + len + 1) >= end) { + DMERR("ran out of memory building ioctl parameter"); + return NULL; + } + + strcpy(out, table->params); + out += len + 1; + /* align next block */ + out = _align(out, 8); + + sp.next = out - out_sp; + memcpy(out_sp, &sp, sp_size); + + return out; +} + +static struct dm_ioctl __init *dm_setup_ioctl(struct dm_device *dev, int flags) +{ + const size_t min_size = 16 * 1024; + size_t len = sizeof(struct dm_ioctl); + struct dm_ioctl *dmi; + struct target *table = dev->table; + char *b, *e; + + if (len < min_size) + len = min_size; + + dmi = kzalloc(len, GFP_KERNEL); + if (!dmi) + return NULL; + + dmi->version[0] = 4; + dmi->version[1] = 0; + dmi->version[2] = 0; + dmi->data_size = len; + dmi->data_start = sizeof(struct dm_ioctl); + dmi->flags = flags; + dmi->dev = dev->minor; + dmi->target_count = dev->table_count; + dmi->event_nr = 1; + + strncpy(dmi->name, dev->name, sizeof(dmi->name)); + + b = (char *) (dmi + 1); + e = (char *) dmi + len; + + while (table != NULL) { + DMDEBUG("device %s adding table '%llu %llu %s %s'", + dev->name, + (unsigned long long) table->start, + (unsigned long long) table->length, + table->type, table->params); + b = dm_add_target(table, b, e); + if (!b) + return NULL; + table = table->next; + } + + return dmi; +} + +static void __init dm_setup_drives(void) +{ + struct dm_device *dev; + int flags; + struct dm_device *devices; + struct dm_ioctl *io = NULL; + + devices = dm_parse_args(); + + for (dev = devices; dev; dev = dev->next) { + io = dm_setup_ioctl(dev, 0); + if (!io) + return; + /* create a new device */ + if (dm_ioctl_cmd(DM_DEV_CREATE, io)) { + DMERR("failed to create device %s", dev->name); + goto out_free; + } + kfree(io); + + flags = DM_STATUS_TABLE_FLAG; + if (dev->ro) + flags |= DM_READONLY_FLAG; + + io = dm_setup_ioctl(dev, flags); + if (!io) + return; + /* load a table into the 'inactive' slot for the device. */ + if (dm_ioctl_cmd(DM_TABLE_LOAD, io)) { + DMERR("failed to load device %s tables", dev->name); + goto out_free; + } + kfree(io); + + io = dm_setup_ioctl(dev, 0); + if (!io) + return; + /* resume and the device should be ready. */ + if (dm_ioctl_cmd(DM_DEV_SUSPEND, io)) { + DMERR("failed to resume device %s", dev->name); + goto out_free; + } + + DMINFO("dm-%d (%s) is ready", dev->minor, dev->name); + } + +out_free: + kfree(io); +} + +__setup("dm=", dm_setup); + +void __init dm_run_setup(void) +{ + if (!dm_early_setup) + return; + DMINFO("attempting early device configuration."); + dm_setup_drives(); +} -- 2.9.3 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel