From: Will Drewry <w...@chromium.org> Add a dm= kernel parameter. It allows 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 <w...@chromium.org> Signed-off-by: Kees Cook <keesc...@chromium.org> [rework to use dm_ioctl calls] Signed-off-by: Enric Balletbo i Serra <enric.balle...@collabora.com> [rework to use concise format | rework for upstream] Signed-off-by: Helen Koike <helen.ko...@collabora.com> --- Hello, In this patch, I constrained the targets allowed to be used by dm=, but I am not entirely familiar with all the targets. I blacklisted the ones mentioned previously and some other that I think doesn't make much sense, but please let me know if you think there are others I should blacklist. Changes since v9: - https://www.redhat.com/archives/linux-lvm/2018-September/msg00016.html - new file: drivers/md/dm-boot.c - most of the parsing code was moved from init/do_mounts_dm.c to drivers/md/dm-boot.c - parsing code was in essence replaced by the concise parser from dmsetup _create_concise function: https://sourceware.org/git/?p=lvm2.git;a=blob;f=libdm/dm-tools/dmsetup.c;h=835fdcdc75e8f0f0f7c4ed46cc9788a6616f58b8;hb=7498f8383397a93db95655ca227257836cbcac82#l1265 the main reason is that this code is already being used/tested by dmsetup, so we can have some level of confidence that it works as expected. Besides this, it also looks more efficient. - Not all targets are allowed to be used by dm=, as pointed previously, there are some risks in creating a mapped device without some validation from userspace (see documentation from the patch listing which targets are allowed). - Instead of using a simple singly linked list (for devices and tables), use the struct list_head. This occupies unnecessary space in the code, but it makes the code cleaner and easier to read and less prone to silly errors. - Documentation and comments were reviewed and refactored, e.g.: * "is to possible" was removed * s/specified as a simple string/specified as a string/ - Added docs above __align function, make it clear that the second parameter @a must be a power of two. - Clean ups: removal of unnecessary includes, macros, variables, some redundant checks and warnings. - when calling ioctls, the code was allocating and freeing the same structure a couple of times. So instead of executing kzalloc/kfree 3 times, execute kmalloc once and reuse the structure after a memset, then finally kfree it once. - update commit message Thanks --- .../admin-guide/kernel-parameters.rst | 1 + .../admin-guide/kernel-parameters.txt | 3 + Documentation/device-mapper/dm-boot.txt | 87 ++++ drivers/md/Makefile | 2 +- drivers/md/dm-boot.c | 433 ++++++++++++++++++ include/linux/device-mapper.h | 6 + init/Makefile | 1 + init/do_mounts.c | 1 + init/do_mounts.h | 10 + init/do_mounts_dm.c | 46 ++ 10 files changed, 589 insertions(+), 1 deletion(-) create mode 100644 Documentation/device-mapper/dm-boot.txt create mode 100644 drivers/md/dm-boot.c 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 b8d0bc07ed0a..bd628865f66f 100644 --- a/Documentation/admin-guide/kernel-parameters.rst +++ b/Documentation/admin-guide/kernel-parameters.rst @@ -91,6 +91,7 @@ parameter is applicable:: AX25 Appropriate AX.25 support 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 92eb1f42240d..a3ff7192b980 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -880,6 +880,9 @@ dis_ucode_ldr [X86] Disable the microcode loader. + dm= [DM] Allows early creation of a device-mapper device. + See Documentation/device-mapper/dm-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 000000000000..14f756b34328 --- /dev/null +++ b/Documentation/device-mapper/dm-boot.txt @@ -0,0 +1,87 @@ +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 when the device-mapper and 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 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=<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, requires userspace validation + "crypt": allowed + "delay": allowed + "era": allowed + "error": allowed + "flakey": allowed + "integrity": allowed + "linear": allowed + "log-writes": allowed + "mirror": allowed + "multipath": allowed + "raid": allowed + "snapshot": allowed + "snapshot-origin": allowed + "striped": allowed + "switch": allowed + "thin": constrained,requires userspace validation + "thin-pool": constrained, requires userspace validation + "unstriped": allowed + "verity": allowed + "writecache": allowed + "zero": constrained, requires userspace validation + "zoned": allowed + +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 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 diff --git a/drivers/md/Makefile b/drivers/md/Makefile index 822f4e8753bc..26ffe4536247 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -5,7 +5,7 @@ dm-mod-y += dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \ dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o \ - dm-rq.o + dm-rq.o dm-boot.o dm-multipath-y += dm-path-selector.o dm-mpath.o dm-snapshot-y += dm-snap.o dm-exception-store.o dm-snap-transient.o \ dm-snap-persistent.o diff --git a/drivers/md/dm-boot.c b/drivers/md/dm-boot.c new file mode 100644 index 000000000000..f886174b08fc --- /dev/null +++ b/drivers/md/dm-boot.c @@ -0,0 +1,433 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * dm-boot.c + * Copyright (C) 2017 The Chromium OS Authors <chromium-os-...@chromium.org> + * + * This file is released under the GPLv2. + */ + +#include <linux/ctype.h> +#include <linux/device-mapper.h> +#include <linux/list.h> + +#define DM_MSG_PREFIX "dm" +#define DM_MAX_DEVICES 256 + +/* See Documentation/device-mapper/dm-boot.txt for dm="..." format details. */ + +struct target { + unsigned long long start; + unsigned long long length; + char *type; + char *params; + struct list_head list; +}; + +struct dm_device { + int minor; + int ro; + char *name; + char *uuid; + int table_count; + struct list_head table; + struct list_head list; +}; + +/** + * _align - align address with the next block + * @ptr: the pointer to be aligned. + * @a: the size of the block to align the pointer. Must be a power of two. + */ +static void __init *_align(void *ptr, unsigned int a) +{ + register unsigned long agn = --a; + + return (void *) (((unsigned long) ptr + agn) & ~agn); +} + +const char *dm_allowed_types[] __initconst = { + /* "cache", constrained, requires userspace validation */ + "crypt", + "delay", + "era", + "error", + "flakey", + "integrity", + "linear", + "log-writes", + "mirror", + "multipath", + "raid", + "snapshot", + "snapshot-origin", + "striped", + "switch", + /* "thin", constrained, requires userspace validation */ + /* "thin-pool", constrained, requires userspace validation */ + "unstriped", + "verity", + "writecache", + /* "zero", constrained, requires userspace validation */ + "zoned", +}; + +static int __init dm_verify_type(const char *type) +{ + unsigned int i; + + for (i = 0; i < ARRAY_SIZE(dm_allowed_types); i++) { + if (!strcmp(dm_allowed_types[i], type)) + return 0; + } + return -EINVAL; +} + +static struct target __init *dm_parse_table_entry(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 && isspace(*ptr); ptr--) + ; + *(++ptr) = '\0'; + + /* trim leading space */ + for (ptr = str; *ptr && isspace(*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 err_free_table; + } + + if (dm_verify_type(type)) { + DMERR("invalid type \"%s\"", type); + goto err_free_table; + } + + table->type = kstrndup(type, strlen(type), GFP_KERNEL); + if (!table->type) { + DMERR("invalid type of table"); + goto err_free_table; + } + + ptr += n; + table->params = kstrndup(ptr, strlen(ptr), GFP_KERNEL); + if (!table->params) { + DMERR("invalid params for table"); + goto err_free_type; + } + + return table; + +err_free_type: + kfree(table->type); +err_free_table: + kfree(table); + return NULL; +} + +/* Parse multiple lines of table */ +static int __init dm_parse_table(struct dm_device *dev, char *str) +{ + char *pos = str, *next_pos; + struct target *table; + + do { + /* Identify and terminate each line */ + next_pos = strchr(pos, ','); + if (next_pos) + *next_pos++ = '\0'; + table = dm_parse_table_entry(pos); + if (!table) { + DMERR("Couldn't parse table \"%s\"", pos); + return -EINVAL; + } + dev->table_count++; + list_add_tail(&table->list, &dev->table); + } while ((pos = next_pos)); + + return 0; +} + +static void __init dm_setup_cleanup(struct list_head *devices) +{ + struct dm_device *dev, *d_tmp; + struct target *target, *t_tmp; + + list_for_each_entry_safe(dev, d_tmp, devices, list) { + list_del(&dev->list); + list_for_each_entry_safe(target, t_tmp, &dev->table, list) { + list_del(&target->list); + kfree(target->type); + kfree(target->params); + kfree(target); + } + kfree(dev); + } +} + +/* code based on _create_concise function from dmsetup.c (lvm2) */ +static int __init dm_parse_args(struct list_head *devices, char *str) +{ + /* name,uuid,minor,flags,table */ + char *fields[5] = { NULL }; + unsigned long ndev = 0; + struct dm_device *dev; + char *c, *n; + int f = 0; + + /* + * Work through input string c, parsing into sets of 5 fields. + * Strip out any characters quoted by backslashes in-place. + * Read characters from c and prepare them in situ for final processing + * at n + */ + c = n = fields[f] = str; + + while (*c) { + /* Quoted character? Skip past quote. */ + if (*c == '\\') { + if (!*(++c)) { + DMERR("Backslash must be followed by another character at end of string."); + *n = '\0'; + DMERR("Parsed %d fields: name: %s uuid: %s minor: %s flags: %s table: %s", + f + 1, fields[0], fields[1], fields[2], + fields[3], fields[4]); + goto out; + } + /* Don't interpret next character */ + *n++ = *c++; + continue; + } + + /* Comma marking end of field? */ + if (*c == ',' && f < 4) { + /* Terminate string */ + *n++ = '\0', c++; + /* Store start of next field */ + fields[++f] = n; + /* Skip any whitespace after field-separating commas */ + while (isspace(*c)) + c++; + continue; + } + + /* Semi-colon marking end of device? */ + if (*c == ';' || *(c + 1) == '\0') { + /* End of input? */ + if (*c != ';') + /* Copy final character */ + *n++ = *c; + + /* Terminate string */ + *n++ = '\0', c++; + + if (f != 4) { + DMERR("Five comma-separated fields are required for each device"); + DMERR("Parsed %d fields: name: %s uuid: %s minor: %s flags: %s table: %s", + f + 1, fields[0], fields[1], fields[2], + fields[3], fields[4]); + goto out; + } + + dev = kzalloc(sizeof(*dev), GFP_KERNEL); + if (!dev) + goto out; + INIT_LIST_HEAD(&dev->table); + list_add_tail(&dev->list, devices); + if (++ndev > DM_MAX_DEVICES) { + DMERR("too many devices %lu > %d", + ndev, DM_MAX_DEVICES); + goto out; + } + + /* Set up parameters */ + dev->name = fields[0]; + dev->uuid = fields[1]; + + if (!*fields[2]) + dev->minor = DM_ANY_MINOR; + else if (kstrtoint(fields[2], 0, &dev->minor)) + goto out; + + if (!strcmp(fields[3], "ro")) + dev->ro = 1; + else if (*fields[3] && strcmp(fields[3], "rw")) { + DMERR("Invalid flags parameter '%s' must be 'ro' or 'rw' or empty.", fields[3]); + goto out; + } + + if (*fields[4] && dm_parse_table(dev, fields[4])) + goto out; + + /* Clear parameters ready for any further devices */ + f = 0; + fields[0] = n; + fields[1] = fields[2] = fields[3] = fields[4] = NULL; + + /* Skip any whitespace after semi-colons */ + while (isspace(*c)) + c++; + + continue; + } + + /* Normal character */ + *n++ = *c++; + } + + if (fields[0] != n) { + *n = '\0'; + DMERR("Incomplete entry: five comma-separated fields are required for each device"); + DMERR("Parsed %d fields: name: %s uuid: %s minor: %s flags: %s table: %s", + f + 1, fields[0], fields[1], fields[2], fields[3], + fields[4]); + goto out; + } + + return 0; + +out: + dm_setup_cleanup(devices); + return -EINVAL; +} + +static char __init *dm_add_target(const struct target *const table, + char *const buf, char *const end) +{ + struct dm_target_spec sp; + char *p = buf; + size_t len; + + len = strlen(table->params); + if (sizeof(struct dm_target_spec) + len >= end - p) { + DMERR("ran out of memory building ioctl parameter"); + return NULL; + } + + p += sizeof(struct dm_target_spec); + strcpy(p, table->params); + p += len + 1; + /* align next block */ + p = _align(p, 8); + + sp.status = 0; + sp.sector_start = table->start; + sp.length = table->length; + strscpy(sp.target_type, table->type, sizeof(sp.target_type)); + sp.next = p - buf; + memcpy(buf, &sp, sizeof(struct dm_target_spec)); + + return p; +} + +static int dm_setup_ioctl(struct dm_ioctl *dmi, size_t len, + struct dm_device *dev, int flags) +{ + struct target *table; + char *b, *e; + + memset(dmi, 0, len); + 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->target_count = dev->table_count; + dmi->event_nr = 1; + + /* Only one between uuid, name and dev should be filled */ + if (*dev->uuid) + strscpy(dmi->uuid, dev->uuid, sizeof(dmi->uuid)); + else if (*dev->name) + strscpy(dmi->name, dev->name, sizeof(dmi->name)); + else if (dev->minor > 0) + dmi->dev = dev->minor; + else { + DMERR("device name or uuid or minor number should be provided"); + return -EINVAL; + } + + b = (char *) (dmi + 1); + e = (char *) dmi + len; + + list_for_each_entry(table, &dev->table, list) { + 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) { + kfree(dmi); + return -EINVAL; + } + } + + return 0; +} + +void __init dm_boot_setup_drives(char *boot_param) +{ + const size_t min_size = 16 * 1024; + const size_t len = sizeof(struct dm_ioctl) > min_size ? + sizeof(struct dm_ioctl) : min_size; + LIST_HEAD(devices); + struct dm_device *dev; + struct dm_ioctl *dmi; + int flags; + + if (dm_parse_args(&devices, boot_param)) + return; + + dmi = kmalloc(len, GFP_KERNEL); + if (!dmi) + return; + + list_for_each_entry(dev, &devices, list) { + flags = dev->minor < 0 ? 0 : DM_PERSISTENT_DEV_FLAG; + if (dm_setup_ioctl(dmi, len, dev, flags)) + goto out_free; + dmi->dev = dev->minor; + /* create a new device */ + if (dm_ioctl_cmd(DM_DEV_CREATE, dmi)) { + DMERR("failed to create device %s", dev->name); + goto out_free; + } + + flags = dev->ro ? DM_READONLY_FLAG : 0; + if (dm_setup_ioctl(dmi, len, dev, flags)) + goto out_free; + /* load a table into the 'inactive' slot for the device. */ + if (dm_ioctl_cmd(DM_TABLE_LOAD, dmi)) { + DMERR("failed to load device %s tables", dev->name); + goto out_free; + } + + if (dm_setup_ioctl(dmi, len, dev, 0)) + goto out_free; + /* resume and the device should be ready. */ + if (dm_ioctl_cmd(DM_DEV_SUSPEND, dmi)) { + DMERR("failed to resume device %s", dev->name); + goto out_free; + } + + DMINFO("dm-%d (%s) is ready", dev->minor, dev->name); + } + +out_free: + kfree(dmi); +} diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 8b2e4ae6a498..a3ad379fd2b7 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -429,6 +429,12 @@ union map_info *dm_get_rq_mapinfo(struct request *rq); */ int dm_ioctl_cmd(unsigned int command, struct dm_ioctl *param); +/* + * Device mapper function to parse and create devices specified in the kernel + * command line boot parameter "dm=" + */ +void __init dm_boot_setup_drives(char *boot_param); + struct queue_limits *dm_get_queue_limits(struct mapped_device *md); /* diff --git a/init/Makefile b/init/Makefile index a3e5ce2bcf08..f814f0ff5974 100644 --- a/init/Makefile +++ b/init/Makefile @@ -19,6 +19,7 @@ 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 e1c9afa9d8c9..d707f12be6e7 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -555,6 +555,7 @@ 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 0bb0806de4ce..0f57528ea324 100644 --- a/init/do_mounts.h +++ b/init/do_mounts.h @@ -61,3 +61,13 @@ 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..6657e2993706 --- /dev/null +++ b/init/do_mounts_dm.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * do_mounts_dm.c + * Copyright (C) 2017 The Chromium OS Authors <chromium-os-...@chromium.org> + * + * This file is released under the GPLv2. + */ +#include <linux/device-mapper.h> + +#include "do_mounts.h" + +#define DM_MSG_PREFIX "init" + +static struct { + char *str; + int early_setup; +} dm_setup_args __initdata; + +/* + * Parse the command-line parameters given to our kernel, but do not + * actually try to invoke the DM device now; that is handled by + * dm_boot_setup_drives after the low-level disk drivers have initialised. + */ +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.str = str; + dm_setup_args.early_setup = 1; + + return 1; +} + +__setup("dm=", dm_setup); + +void __init dm_run_setup(void) +{ + if (!dm_setup_args.early_setup) + return; + DMINFO("attempting early device configuration."); + dm_boot_setup_drives(dm_setup_args.str); +} -- 2.19.1
