block/partitions/cmdline.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2013 HUAWEI
  * Author: Cai Zhiyong <caizhiyong@huawei.com>
  *
  * Read block device partition table from the command line.
  * Typically used for fixed block (eMMC) embedded devices.
  * It has no MBR, so saves storage space. Bootloader can be easily accessed
  * by absolute address of data on the block device.
  * Users can easily change the partition.
  *
  * The format for the command line is just like mtdparts.
  *
  * For further information, see "Documentation/block/cmdline-partition.rst"
  *
  */
 #include <linux/blkdev.h>
 #include <linux/fs.h>
 #include <linux/slab.h>
 #include "check.h"


 /* partition flags */
 #define PF_RDONLY                   0x01 /* Device is read only */
 #define PF_POWERUP_LOCK             0x02 /* Always locked after reset */

 struct cmdline_subpart {
 	char name[BDEVNAME_SIZE]; /* partition name, such as 'rootfs' */
 	sector_t from;
 	sector_t size;
 	int flags;
 	struct cmdline_subpart *next_subpart;
 };

 struct cmdline_parts {
 	char name[BDEVNAME_SIZE]; /* block device, such as 'mmcblk0' */
 	unsigned int nr_subparts;
 	struct cmdline_subpart *subpart;
 	struct cmdline_parts *next_parts;
 };

 static int parse_subpart(struct cmdline_subpart **subpart, char *partdef)
 {
 	int ret = 0;
 	struct cmdline_subpart *new_subpart;

 	*subpart = NULL;

 	new_subpart = kzalloc(sizeof(struct cmdline_subpart), GFP_KERNEL);
 	if (!new_subpart)
 		return -ENOMEM;

 	if (*partdef == '-') {
 		new_subpart->size = (sector_t)(~0ULL);
 		partdef++;
 	} else {
 		new_subpart->size = (sector_t)memparse(partdef, &partdef);
 		if (new_subpart->size < (sector_t)PAGE_SIZE) {
 			pr_warn("cmdline partition size is invalid.");
 			ret = -EINVAL;
 			goto fail;
 		}
 	}

 	if (*partdef == '@') {
 		partdef++;
 		new_subpart->from = (sector_t)memparse(partdef, &partdef);
 	} else {
 		new_subpart->from = (sector_t)(~0ULL);
 	}

 	if (*partdef == '(') {
 		int length;
 		char *next = strchr(++partdef, ')');

 		if (!next) {
 			pr_warn("cmdline partition format is invalid.");
 			ret = -EINVAL;
 			goto fail;
 		}

 		length = min_t(int, next - partdef,
 			       sizeof(new_subpart->name) - 1);
 		strscpy(new_subpart->name, partdef, length);

 		partdef = ++next;
 	} else
 		new_subpart->name[0] = '\0';

 	new_subpart->flags = 0;

 	if (!strncmp(partdef, "ro", 2)) {
 		new_subpart->flags |= PF_RDONLY;
 		partdef += 2;
 	}

 	if (!strncmp(partdef, "lk", 2)) {
 		new_subpart->flags |= PF_POWERUP_LOCK;
 		partdef += 2;
 	}

 	*subpart = new_subpart;
 	return 0;
 fail:
 	kfree(new_subpart);
 	return ret;
 }

 static void free_subpart(struct cmdline_parts *parts)
 {
 	struct cmdline_subpart *subpart;

 	while (parts->subpart) {
 		subpart = parts->subpart;
 		parts->subpart = subpart->next_subpart;
 		kfree(subpart);
 	}
 }

 static int parse_parts(struct cmdline_parts **parts, const char *bdevdef)
 {
 	int ret = -EINVAL;
 	char *next;
 	int length;
 	struct cmdline_subpart **next_subpart;
 	struct cmdline_parts *newparts;
 	char buf[BDEVNAME_SIZE + 32 + 4];

 	*parts = NULL;

 	newparts = kzalloc(sizeof(struct cmdline_parts), GFP_KERNEL);
 	if (!newparts)
 		return -ENOMEM;

 	next = strchr(bdevdef, ':');
 	if (!next) {
 		pr_warn("cmdline partition has no block device.");
 		goto fail;
 	}

 	length = min_t(int, next - bdevdef, sizeof(newparts->name) - 1);
 	strscpy(newparts->name, bdevdef, length);
 	newparts->nr_subparts = 0;

 	next_subpart = &newparts->subpart;

 	while (next && *(++next)) {
 		bdevdef = next;
 		next = strchr(bdevdef, ',');

 		length = (!next) ? (sizeof(buf) - 1) :
 			min_t(int, next - bdevdef, sizeof(buf) - 1);

 		strscpy(buf, bdevdef, length);

 		ret = parse_subpart(next_subpart, buf);
 		if (ret)
 			goto fail;

 		newparts->nr_subparts++;
 		next_subpart = &(*next_subpart)->next_subpart;
 	}

 	if (!newparts->subpart) {
 		pr_warn("cmdline partition has no valid partition.");
 		ret = -EINVAL;
 		goto fail;
 	}

 	*parts = newparts;

 	return 0;
 fail:
 	free_subpart(newparts);
 	kfree(newparts);
 	return ret;
 }

 static void cmdline_parts_free(struct cmdline_parts **parts)
 {
 	struct cmdline_parts *next_parts;

 	while (*parts) {
 		next_parts = (*parts)->next_parts;
 		free_subpart(*parts);
 		kfree(*parts);
 		*parts = next_parts;
 	}
 }

 static int cmdline_parts_parse(struct cmdline_parts **parts,
 		const char *cmdline)
 {
 	int ret;
 	char *buf;
 	char *pbuf;
 	char *next;
 	struct cmdline_parts **next_parts;

 	*parts = NULL;

 	next = pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;

 	next_parts = parts;

 	while (next && *pbuf) {
 		next = strchr(pbuf, ';');
 		if (next)
 			*next = '\0';

 		ret = parse_parts(next_parts, pbuf);
 		if (ret)
 			goto fail;

 		if (next)
 			pbuf = ++next;

 		next_parts = &(*next_parts)->next_parts;
 	}

 	if (!*parts) {
 		pr_warn("cmdline partition has no valid partition.");
 		ret = -EINVAL;
 		goto fail;
 	}

 	ret = 0;
 done:
 	kfree(buf);
 	return ret;

 fail:
 	cmdline_parts_free(parts);
 	goto done;
 }

 static struct cmdline_parts *cmdline_parts_find(struct cmdline_parts *parts,
 					 const char *bdev)
 {
 	while (parts && strncmp(bdev, parts->name, sizeof(parts->name)))
 		parts = parts->next_parts;
 	return parts;
 }

 static char *cmdline;
 static struct cmdline_parts *bdev_parts;

 static int add_part(int slot, struct cmdline_subpart *subpart,
 		struct parsed_partitions *state)
 {
 	int label_min;
 	struct partition_meta_info *info;
 	char tmp[sizeof(info->volname) + 4];

 	if (slot >= state->limit)
 		return 1;

 	put_partition(state, slot, subpart->from >> 9,
 		      subpart->size >> 9);

 	info = &state->parts[slot].info;

 	label_min = min_t(int, sizeof(info->volname) - 1,
 			  sizeof(subpart->name));
 	strscpy(info->volname, subpart->name, label_min);

 	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
 	strlcat(state->pp_buf, tmp, PAGE_SIZE);

 	state->parts[slot].has_info = true;

 	return 0;
 }

 static int cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
 		struct parsed_partitions *state)
 {
 	sector_t from = 0;
 	struct cmdline_subpart *subpart;
 	int slot = 1;

 	for (subpart = parts->subpart; subpart;
 	     subpart = subpart->next_subpart, slot++) {
 		if (subpart->from == (sector_t)(~0ULL))
 			subpart->from = from;
 		else
 			from = subpart->from;

 		if (from >= disk_size)
 			break;

 		if (subpart->size > (disk_size - from))
 			subpart->size = disk_size - from;

 		from += subpart->size;

 		if (add_part(slot, subpart, state))
 			break;
 	}

 	return slot;
 }

 static int __init cmdline_parts_setup(char *s)
 {
 	cmdline = s;
 	return 1;
 }
 __setup("blkdevparts=", cmdline_parts_setup);

 static bool has_overlaps(sector_t from, sector_t size,
 			 sector_t from2, sector_t size2)
 {
 	sector_t end = from + size;
 	sector_t end2 = from2 + size2;

 	if (from >= from2 && from < end2)
 		return true;

 	if (end > from2 && end <= end2)
 		return true;

 	if (from2 >= from && from2 < end)
 		return true;

 	if (end2 > from && end2 <= end)
 		return true;

 	return false;
 }

 static inline void overlaps_warns_header(void)
 {
 	pr_warn("Overlapping partitions are used in command line partitions.");
 	pr_warn("Don't use filesystems on overlapping partitions:");
 }

 static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
 {
 	int i;
 	bool header = true;

 	for (; slot < state->limit && state->parts[slot].has_info; slot++) {
 		for (i = slot+1; i < state->limit && state->parts[i].has_info;
 		     i++) {
 			if (has_overlaps(state->parts[slot].from,
 					 state->parts[slot].size,
 					 state->parts[i].from,
 					 state->parts[i].size)) {
 				if (header) {
 					header = false;
 					overlaps_warns_header();
 				}
 				pr_warn("%s[%llu,%llu] overlaps with "
 					"%s[%llu,%llu].",
 					state->parts[slot].info.volname,
 					(u64)state->parts[slot].from << 9,
 					(u64)state->parts[slot].size << 9,
 					state->parts[i].info.volname,
 					(u64)state->parts[i].from << 9,
 					(u64)state->parts[i].size << 9);
 			}
 		}
 	}
 }

 /*
  * Purpose: allocate cmdline partitions.
  * Returns:
  * -1 if unable to read the partition table
  *  0 if this isn't our partition table
  *  1 if successful
  */
 int cmdline_partition(struct parsed_partitions *state)
 {
 	sector_t disk_size;
 	struct cmdline_parts *parts;

 	if (cmdline) {
 		if (bdev_parts)
 			cmdline_parts_free(&bdev_parts);

 		if (cmdline_parts_parse(&bdev_parts, cmdline)) {
 			cmdline = NULL;
 			return -1;
 		}
 		cmdline = NULL;
 	}

 	if (!bdev_parts)
 		return 0;

 	parts = cmdline_parts_find(bdev_parts, state->disk->disk_name);
 	if (!parts)
 		return 0;

 	disk_size = get_capacity(state->disk) << 9;

 	cmdline_parts_set(parts, disk_size, state);
 	cmdline_parts_verifier(1, state);

 	strlcat(state->pp_buf, "\n", PAGE_SIZE);

 	return 1;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (C) 2013 HUAWEI
	* Author: Cai Zhiyong <caizhiyong@huawei.com>
	*
	* Read block device partition table from the command line.
	* Typically used for fixed block (eMMC) embedded devices.
	* It has no MBR, so saves storage space. Bootloader can be easily accessed
	* by absolute address of data on the block device.
	* Users can easily change the partition.
	*
	* The format for the command line is just like mtdparts.
	*
	* For further information, see "Documentation/block/cmdline-partition.rst"
	*
	*/
	#include <linux/blkdev.h>
	#include <linux/fs.h>
	#include <linux/slab.h>
	#include "check.h"


	/* partition flags */
	#define PF_RDONLY 0x01 /* Device is read only */
	#define PF_POWERUP_LOCK 0x02 /* Always locked after reset */

	struct cmdline_subpart {
	char name[BDEVNAME_SIZE]; /* partition name, such as 'rootfs' */
	sector_t from;
	sector_t size;
	int flags;
	struct cmdline_subpart *next_subpart;
	};

	struct cmdline_parts {
	char name[BDEVNAME_SIZE]; /* block device, such as 'mmcblk0' */
	unsigned int nr_subparts;
	struct cmdline_subpart *subpart;
	struct cmdline_parts *next_parts;
	};

	static int parse_subpart(struct cmdline_subpart *subpart, char partdef)
	{
	int ret = 0;
	struct cmdline_subpart *new_subpart;

	*subpart = NULL;

	new_subpart = kzalloc(sizeof(struct cmdline_subpart), GFP_KERNEL);
	if (!new_subpart)
	return -ENOMEM;

	if (*partdef == '-') {
	new_subpart->size = (sector_t)(~0ULL);
	partdef++;
	} else {
	new_subpart->size = (sector_t)memparse(partdef, &partdef);
	if (new_subpart->size < (sector_t)PAGE_SIZE) {
	pr_warn("cmdline partition size is invalid.");
	ret = -EINVAL;
	goto fail;
	}
	}

	if (*partdef == '@') {
	partdef++;
	new_subpart->from = (sector_t)memparse(partdef, &partdef);
	} else {
	new_subpart->from = (sector_t)(~0ULL);
	}

	if (*partdef == '(') {
	int length;
	char *next = strchr(++partdef, ')');

	if (!next) {
	pr_warn("cmdline partition format is invalid.");
	ret = -EINVAL;
	goto fail;
	}

	length = min_t(int, next - partdef,
	sizeof(new_subpart->name) - 1);
	strscpy(new_subpart->name, partdef, length);

	partdef = ++next;
	} else
	new_subpart->name[0] = '\0';

	new_subpart->flags = 0;

	if (!strncmp(partdef, "ro", 2)) {
	new_subpart->flags \|= PF_RDONLY;
	partdef += 2;
	}

	if (!strncmp(partdef, "lk", 2)) {
	new_subpart->flags \|= PF_POWERUP_LOCK;
	partdef += 2;
	}

	*subpart = new_subpart;
	return 0;
	fail:
	kfree(new_subpart);
	return ret;
	}

	static void free_subpart(struct cmdline_parts *parts)
	{
	struct cmdline_subpart *subpart;

	while (parts->subpart) {
	subpart = parts->subpart;
	parts->subpart = subpart->next_subpart;
	kfree(subpart);
	}
	}

	static int parse_parts(struct cmdline_parts *parts, const char bdevdef)
	{
	int ret = -EINVAL;
	char *next;
	int length;
	struct cmdline_subpart **next_subpart;
	struct cmdline_parts *newparts;
	char buf[BDEVNAME_SIZE + 32 + 4];

	*parts = NULL;

	newparts = kzalloc(sizeof(struct cmdline_parts), GFP_KERNEL);
	if (!newparts)
	return -ENOMEM;

	next = strchr(bdevdef, ':');
	if (!next) {
	pr_warn("cmdline partition has no block device.");
	goto fail;
	}

	length = min_t(int, next - bdevdef, sizeof(newparts->name) - 1);
	strscpy(newparts->name, bdevdef, length);
	newparts->nr_subparts = 0;

	next_subpart = &newparts->subpart;

	while (next && *(++next)) {
	bdevdef = next;
	next = strchr(bdevdef, ',');

	length = (!next) ? (sizeof(buf) - 1) :
	min_t(int, next - bdevdef, sizeof(buf) - 1);

	strscpy(buf, bdevdef, length);

	ret = parse_subpart(next_subpart, buf);
	if (ret)
	goto fail;

	newparts->nr_subparts++;
	next_subpart = &(*next_subpart)->next_subpart;
	}

	if (!newparts->subpart) {
	pr_warn("cmdline partition has no valid partition.");
	ret = -EINVAL;
	goto fail;
	}

	*parts = newparts;

	return 0;
	fail:
	free_subpart(newparts);
	kfree(newparts);
	return ret;
	}

	static void cmdline_parts_free(struct cmdline_parts **parts)
	{
	struct cmdline_parts *next_parts;

	while (*parts) {
	next_parts = (*parts)->next_parts;
	free_subpart(*parts);
	kfree(*parts);
	*parts = next_parts;
	}
	}

	static int cmdline_parts_parse(struct cmdline_parts **parts,
	const char *cmdline)
	{
	int ret;
	char *buf;
	char *pbuf;
	char *next;
	struct cmdline_parts **next_parts;

	*parts = NULL;

	next = pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;

	next_parts = parts;

	while (next && *pbuf) {
	next = strchr(pbuf, ';');
	if (next)
	*next = '\0';

	ret = parse_parts(next_parts, pbuf);
	if (ret)
	goto fail;

	if (next)
	pbuf = ++next;

	next_parts = &(*next_parts)->next_parts;
	}

	if (!*parts) {
	pr_warn("cmdline partition has no valid partition.");
	ret = -EINVAL;
	goto fail;
	}

	ret = 0;
	done:
	kfree(buf);
	return ret;

	fail:
	cmdline_parts_free(parts);
	goto done;
	}

	static struct cmdline_parts cmdline_parts_find(struct cmdline_parts parts,
	const char *bdev)
	{
	while (parts && strncmp(bdev, parts->name, sizeof(parts->name)))
	parts = parts->next_parts;
	return parts;
	}

	static char *cmdline;
	static struct cmdline_parts *bdev_parts;

	static int add_part(int slot, struct cmdline_subpart *subpart,
	struct parsed_partitions *state)
	{
	int label_min;
	struct partition_meta_info *info;
	char tmp[sizeof(info->volname) + 4];

	if (slot >= state->limit)
	return 1;

	put_partition(state, slot, subpart->from >> 9,
	subpart->size >> 9);

	info = &state->parts[slot].info;

	label_min = min_t(int, sizeof(info->volname) - 1,
	sizeof(subpart->name));
	strscpy(info->volname, subpart->name, label_min);

	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
	strlcat(state->pp_buf, tmp, PAGE_SIZE);

	state->parts[slot].has_info = true;

	return 0;
	}

	static int cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
	struct parsed_partitions *state)
	{
	sector_t from = 0;
	struct cmdline_subpart *subpart;
	int slot = 1;

	for (subpart = parts->subpart; subpart;
	subpart = subpart->next_subpart, slot++) {
	if (subpart->from == (sector_t)(~0ULL))
	subpart->from = from;
	else
	from = subpart->from;

	if (from >= disk_size)
	break;

	if (subpart->size > (disk_size - from))
	subpart->size = disk_size - from;

	from += subpart->size;

	if (add_part(slot, subpart, state))
	break;
	}

	return slot;
	}

	static int __init cmdline_parts_setup(char *s)
	{
	cmdline = s;
	return 1;
	}
	__setup("blkdevparts=", cmdline_parts_setup);

	static bool has_overlaps(sector_t from, sector_t size,
	sector_t from2, sector_t size2)
	{
	sector_t end = from + size;
	sector_t end2 = from2 + size2;

	if (from >= from2 && from < end2)
	return true;

	if (end > from2 && end <= end2)
	return true;

	if (from2 >= from && from2 < end)
	return true;

	if (end2 > from && end2 <= end)
	return true;

	return false;
	}

	static inline void overlaps_warns_header(void)
	{
	pr_warn("Overlapping partitions are used in command line partitions.");
	pr_warn("Don't use filesystems on overlapping partitions:");
	}

	static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
	{
	int i;
	bool header = true;

	for (; slot < state->limit && state->parts[slot].has_info; slot++) {
	for (i = slot+1; i < state->limit && state->parts[i].has_info;
	i++) {
	if (has_overlaps(state->parts[slot].from,
	state->parts[slot].size,
	state->parts[i].from,
	state->parts[i].size)) {
	if (header) {
	header = false;
	overlaps_warns_header();
	}
	pr_warn("%s[%llu,%llu] overlaps with "
	"%s[%llu,%llu].",
	state->parts[slot].info.volname,
	(u64)state->parts[slot].from << 9,
	(u64)state->parts[slot].size << 9,
	state->parts[i].info.volname,
	(u64)state->parts[i].from << 9,
	(u64)state->parts[i].size << 9);
	}
	}
	}
	}

	/*
	* Purpose: allocate cmdline partitions.
	* Returns:
	* -1 if unable to read the partition table
	* 0 if this isn't our partition table
	* 1 if successful
	*/
	int cmdline_partition(struct parsed_partitions *state)
	{
	sector_t disk_size;
	struct cmdline_parts *parts;

	if (cmdline) {
	if (bdev_parts)
	cmdline_parts_free(&bdev_parts);

	if (cmdline_parts_parse(&bdev_parts, cmdline)) {
	cmdline = NULL;
	return -1;
	}
	cmdline = NULL;
	}

	if (!bdev_parts)
	return 0;

	parts = cmdline_parts_find(bdev_parts, state->disk->disk_name);
	if (!parts)
	return 0;

	disk_size = get_capacity(state->disk) << 9;

	cmdline_parts_set(parts, disk_size, state);
	cmdline_parts_verifier(1, state);

	strlcat(state->pp_buf, "\n", PAGE_SIZE);

	return 1;
	}