LXR linux/block/partitions/cmdline.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2013 HUAWEI
   4 * Author: Cai Zhiyong <caizhiyong@huawei.com>
   5 *
   6 * Read block device partition table from the command line.
   7 * Typically used for fixed block (eMMC) embedded devices.
   8 * It has no MBR, so saves storage space. Bootloader can be easily accessed
   9 * by absolute address of data on the block device.
  10 * Users can easily change the partition.
  11 *
  12 * The format for the command line is just like mtdparts.
  13 *
  14 * For further information, see "Documentation/block/cmdline-partition.rst"
  15 *
  16 */
  17
  18#include <linux/cmdline-parser.h>
  19
  20#include "check.h"
  21#include "cmdline.h"
  22
  23static char *cmdline;
  24static struct cmdline_parts *bdev_parts;
  25
  26static int add_part(int slot, struct cmdline_subpart *subpart, void *param)
  27{
  28        int label_min;
  29        struct partition_meta_info *info;
  30        char tmp[sizeof(info->volname) + 4];
  31        struct parsed_partitions *state = (struct parsed_partitions *)param;
  32
  33        if (slot >= state->limit)
  34                return 1;
  35
  36        put_partition(state, slot, subpart->from >> 9,
  37                      subpart->size >> 9);
  38
  39        info = &state->parts[slot].info;
  40
  41        label_min = min_t(int, sizeof(info->volname) - 1,
  42                          sizeof(subpart->name));
  43        strncpy(info->volname, subpart->name, label_min);
  44        info->volname[label_min] = '\0';
  45
  46        snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
  47        strlcat(state->pp_buf, tmp, PAGE_SIZE);
  48
  49        state->parts[slot].has_info = true;
  50
  51        return 0;
  52}
  53
  54static int __init cmdline_parts_setup(char *s)
  55{
  56        cmdline = s;
  57        return 1;
  58}
  59__setup("blkdevparts=", cmdline_parts_setup);
  60
  61static bool has_overlaps(sector_t from, sector_t size,
  62                         sector_t from2, sector_t size2)
  63{
  64        sector_t end = from + size;
  65        sector_t end2 = from2 + size2;
  66
  67        if (from >= from2 && from < end2)
  68                return true;
  69
  70        if (end > from2 && end <= end2)
  71                return true;
  72
  73        if (from2 >= from && from2 < end)
  74                return true;
  75
  76        if (end2 > from && end2 <= end)
  77                return true;
  78
  79        return false;
  80}
  81
  82static inline void overlaps_warns_header(void)
  83{
  84        pr_warn("Overlapping partitions are used in command line partitions.");
  85        pr_warn("Don't use filesystems on overlapping partitions:");
  86}
  87
  88static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
  89{
  90        int i;
  91        bool header = true;
  92
  93        for (; slot < state->limit && state->parts[slot].has_info; slot++) {
  94                for (i = slot+1; i < state->limit && state->parts[i].has_info;
  95                     i++) {
  96                        if (has_overlaps(state->parts[slot].from,
  97                                         state->parts[slot].size,
  98                                         state->parts[i].from,
  99                                         state->parts[i].size)) {
 100                                if (header) {
 101                                        header = false;
 102                                        overlaps_warns_header();
 103                                }
 104                                pr_warn("%s[%llu,%llu] overlaps with "
 105                                        "%s[%llu,%llu].",
 106                                        state->parts[slot].info.volname,
 107                                        (u64)state->parts[slot].from << 9,
 108                                        (u64)state->parts[slot].size << 9,
 109                                        state->parts[i].info.volname,
 110                                        (u64)state->parts[i].from << 9,
 111                                        (u64)state->parts[i].size << 9);
 112                        }
 113                }
 114        }
 115}
 116
 117/*
 118 * Purpose: allocate cmdline partitions.
 119 * Returns:
 120 * -1 if unable to read the partition table
 121 *  0 if this isn't our partition table
 122 *  1 if successful
 123 */
 124int cmdline_partition(struct parsed_partitions *state)
 125{
 126        sector_t disk_size;
 127        char bdev[BDEVNAME_SIZE];
 128        struct cmdline_parts *parts;
 129
 130        if (cmdline) {
 131                if (bdev_parts)
 132                        cmdline_parts_free(&bdev_parts);
 133
 134                if (cmdline_parts_parse(&bdev_parts, cmdline)) {
 135                        cmdline = NULL;
 136                        return -1;
 137                }
 138                cmdline = NULL;
 139        }
 140
 141        if (!bdev_parts)
 142                return 0;
 143
 144        bdevname(state->bdev, bdev);
 145        parts = cmdline_parts_find(bdev_parts, bdev);
 146        if (!parts)
 147                return 0;
 148
 149        disk_size = get_capacity(state->bdev->bd_disk) << 9;
 150
 151        cmdline_parts_set(parts, disk_size, 1, add_part, (void *)state);
 152        cmdline_parts_verifier(1, state);
 153
 154        strlcat(state->pp_buf, "\n", PAGE_SIZE);
 155
 156        return 1;
 157}
 158