package/system/mtd/src/linksys_bootcount.c

   1 /*
   2  * Linksys boot counter reset code for mtd
   3  *
   4  * Copyright (C) 2013 Jonas Gorski <jogo@openwrt.org>
   5  * Portions Copyright (c) 2019, Jeff Kletsky
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License v2
   9  * as published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  *
  20  */
  21
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <stddef.h>
  25 #include <unistd.h>
  26 #include <fcntl.h>
  27 #include <sys/mman.h>
  28 #include <sys/stat.h>
  29 #include <endian.h>
  30 #include <string.h>
  31 #include <errno.h>
  32 #include <stdint.h>
  33 #include <syslog.h>
  34
  35 #include <sys/ioctl.h>
  36 #include <mtd/mtd-user.h>
  37
  38 #include "mtd.h"
  39
  40 #define BOOTCOUNT_MAGIC 0x20110811
  41
  42 /*
  43  * EA6350v3, and potentially other NOR-boot devices,
  44  * use an offset increment of 16 between records,
  45  * not mtd_info_user.writesize (often 1 on NOR devices).
  46  */
  47
  48 #define BC_OFFSET_INCREMENT_MIN 16
  49
  50
  51
  52 #define DLOG_OPEN()
  53
  54 #define DLOG_ERR(...) do {                                                     \
  55                 fprintf(stderr, "ERROR: " __VA_ARGS__); fprintf(stderr, "\n"); \
  56         } while (0)
  57
  58 #define DLOG_NOTICE(...) do {                                           \
  59                 fprintf(stderr, __VA_ARGS__); fprintf(stderr, "\n");    \
  60         } while (0)
  61
  62 #define DLOG_DEBUG(...)
  63
  64
  65
  66 struct bootcounter {
  67         uint32_t magic;
  68         uint32_t count;
  69         uint32_t checksum;
  70 };
  71
  72 static char page[2048];
  73
  74 int mtd_resetbc(const char *mtd)
  75 {
  76         struct mtd_info_user mtd_info;
  77         struct bootcounter *curr = (struct bootcounter *)page;
  78         unsigned int i;
  79         unsigned int bc_offset_increment;
  80         int last_count = 0;
  81         int num_bc;
  82         int fd;
  83         int ret;
  84         int retval = 0;
  85
  86         DLOG_OPEN();
  87
  88         fd = mtd_check_open(mtd);
  89
  90         if (ioctl(fd, MEMGETINFO, &mtd_info) < 0) {
  91                 DLOG_ERR("Unable to obtain mtd_info for given partition name.");
  92
  93                 retval = -1;
  94                 goto out;
  95         }
  96
  97
  98         /* Detect need to override increment (for EA6350v3) */
  99
 100         if (mtd_info.writesize < BC_OFFSET_INCREMENT_MIN) {
 101
 102                 bc_offset_increment = BC_OFFSET_INCREMENT_MIN;
 103                 DLOG_DEBUG("Offset increment set to %i for writesize of %i",
 104                            bc_offset_increment, mtd_info.writesize);
 105         } else {
 106
 107                 bc_offset_increment = mtd_info.writesize;
 108         }
 109
 110         num_bc = mtd_info.size / bc_offset_increment;
 111
 112         for (i = 0; i < num_bc; i++) {
 113                 pread(fd, curr, sizeof(*curr), i * bc_offset_increment);
 114
 115                 /* Existing code assumes erase is to 0xff; left as-is (2019) */
 116
 117                 if (curr->magic != BOOTCOUNT_MAGIC &&
 118                     curr->magic != 0xffffffff) {
 119                         DLOG_ERR("Unexpected magic %08x at offset %08x; aborting.",
 120                                  curr->magic, i * bc_offset_increment);
 121
 122                         retval = -2;
 123                         goto out;
 124                 }
 125
 126                 if (curr->magic == 0xffffffff)
 127                         break;
 128
 129                 last_count = curr->count;
 130         }
 131
 132
 133         if (last_count == 0) {  /* bootcount is already 0 */
 134
 135                 retval = 0;
 136                 goto out;
 137         }
 138
 139
 140         if (i == num_bc) {
 141                 DLOG_NOTICE("Boot-count log full with %i entries; erasing (expected occasionally).",
 142                             i);
 143
 144                 struct erase_info_user erase_info;
 145                 erase_info.start = 0;
 146                 erase_info.length = mtd_info.size;
 147
 148                 ret = ioctl(fd, MEMERASE, &erase_info);
 149                 if (ret < 0) {
 150                         DLOG_ERR("Failed to erase boot-count log MTD; ioctl() MEMERASE returned %i",
 151                                  ret);
 152
 153                         retval = -3;
 154                         goto out;
 155                 }
 156
 157                 i = 0;
 158         }
 159
 160         memset(curr, 0xff, bc_offset_increment);
 161
 162         curr->magic = BOOTCOUNT_MAGIC;
 163         curr->count = 0;
 164         curr->checksum = BOOTCOUNT_MAGIC;
 165
 166         /* Assumes bc_offset_increment is a multiple of mtd_info.writesize */
 167
 168         ret = pwrite(fd, curr, bc_offset_increment, i * bc_offset_increment);
 169         if (ret < 0) {
 170                 DLOG_ERR("Failed to write boot-count log entry; pwrite() returned %i",
 171                          errno);
 172                 retval = -4;
 173                 goto out;
 174
 175         } else {
 176                 sync();
 177
 178                 DLOG_NOTICE("Boot count sucessfully reset to zero.");
 179
 180                 retval = 0;
 181                 goto out;
 182         }
 183
 184 out:
 185         close(fd);
 186         return retval;
 187 }