cmdline.c
// 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);
strncpy(new_subpart->name, partdef, length);
new_subpart->name[length] = '\0';
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);
strncpy(newparts->name, bdevdef, length);
newparts->name[length] = '\0';
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);
strncpy(buf, bdevdef, length);
buf[length] = '\0';
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));
strncpy(info->volname, subpart->name, label_min);
info->volname[label_min] = '\0';
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;
}