block/t10-pi.c

   1 /*
   2  * t10_pi.c - Functions for generating and verifying T10 Protection
   3  *            Information.
   4  *
   5  * Copyright (C) 2007, 2008, 2014 Oracle Corporation
   6  * Written by: Martin K. Petersen <martin.petersen@oracle.com>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License version
  10  * 2 as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; see the file COPYING.  If not, write to
  19  * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
  20  * USA.
  21  *
  22  */
  23
  24 #include <linux/t10-pi.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/crc-t10dif.h>
  27 #include <net/checksum.h>
  28
  29 typedef __be16 (csum_fn) (void *, unsigned int);
  30
  31 static const __be16 APP_ESCAPE = (__force __be16) 0xffff;
  32 static const __be32 REF_ESCAPE = (__force __be32) 0xffffffff;
  33
  34 static __be16 t10_pi_crc_fn(void *data, unsigned int len)
  35 {
  36         return cpu_to_be16(crc_t10dif(data, len));
  37 }
  38
  39 static __be16 t10_pi_ip_fn(void *data, unsigned int len)
  40 {
  41         return (__force __be16)ip_compute_csum(data, len);
  42 }
  43
  44 /*
  45  * Type 1 and Type 2 protection use the same format: 16 bit guard tag,
  46  * 16 bit app tag, 32 bit reference tag. Type 3 does not define the ref
  47  * tag.
  48  */
  49 static int t10_pi_generate(struct blk_integrity_iter *iter, csum_fn *fn,
  50                            unsigned int type)
  51 {
  52         unsigned int i;
  53
  54         for (i = 0 ; i < iter->data_size ; i += iter->interval) {
  55                 struct t10_pi_tuple *pi = iter->prot_buf;
  56
  57                 pi->guard_tag = fn(iter->data_buf, iter->interval);
  58                 pi->app_tag = 0;
  59
  60                 if (type == 1)
  61                         pi->ref_tag = cpu_to_be32(lower_32_bits(iter->seed));
  62                 else
  63                         pi->ref_tag = 0;
  64
  65                 iter->data_buf += iter->interval;
  66                 iter->prot_buf += sizeof(struct t10_pi_tuple);
  67                 iter->seed++;
  68         }
  69
  70         return 0;
  71 }
  72
  73 static int t10_pi_verify(struct blk_integrity_iter *iter, csum_fn *fn,
  74                                 unsigned int type)
  75 {
  76         unsigned int i;
  77
  78         for (i = 0 ; i < iter->data_size ; i += iter->interval) {
  79                 struct t10_pi_tuple *pi = iter->prot_buf;
  80                 __be16 csum;
  81
  82                 switch (type) {
  83                 case 1:
  84                 case 2:
  85                         if (pi->app_tag == APP_ESCAPE)
  86                                 goto next;
  87
  88                         if (be32_to_cpu(pi->ref_tag) !=
  89                             lower_32_bits(iter->seed)) {
  90                                 pr_err("%s: ref tag error at location %llu " \
  91                                        "(rcvd %u)\n", iter->disk_name,
  92                                        (unsigned long long)
  93                                        iter->seed, be32_to_cpu(pi->ref_tag));
  94                                 return -EILSEQ;
  95                         }
  96                         break;
  97                 case 3:
  98                         if (pi->app_tag == APP_ESCAPE &&
  99                             pi->ref_tag == REF_ESCAPE)
 100                                 goto next;
 101                         break;
 102                 }
 103
 104                 csum = fn(iter->data_buf, iter->interval);
 105
 106                 if (pi->guard_tag != csum) {
 107                         pr_err("%s: guard tag error at sector %llu " \
 108                                "(rcvd %04x, want %04x)\n", iter->disk_name,
 109                                (unsigned long long)iter->seed,
 110                                be16_to_cpu(pi->guard_tag), be16_to_cpu(csum));
 111                         return -EILSEQ;
 112                 }
 113
 114 next:
 115                 iter->data_buf += iter->interval;
 116                 iter->prot_buf += sizeof(struct t10_pi_tuple);
 117                 iter->seed++;
 118         }
 119
 120         return 0;
 121 }
 122
 123 static int t10_pi_type1_generate_crc(struct blk_integrity_iter *iter)
 124 {
 125         return t10_pi_generate(iter, t10_pi_crc_fn, 1);
 126 }
 127
 128 static int t10_pi_type1_generate_ip(struct blk_integrity_iter *iter)
 129 {
 130         return t10_pi_generate(iter, t10_pi_ip_fn, 1);
 131 }
 132
 133 static int t10_pi_type1_verify_crc(struct blk_integrity_iter *iter)
 134 {
 135         return t10_pi_verify(iter, t10_pi_crc_fn, 1);
 136 }
 137
 138 static int t10_pi_type1_verify_ip(struct blk_integrity_iter *iter)
 139 {
 140         return t10_pi_verify(iter, t10_pi_ip_fn, 1);
 141 }
 142
 143 static int t10_pi_type3_generate_crc(struct blk_integrity_iter *iter)
 144 {
 145         return t10_pi_generate(iter, t10_pi_crc_fn, 3);
 146 }
 147
 148 static int t10_pi_type3_generate_ip(struct blk_integrity_iter *iter)
 149 {
 150         return t10_pi_generate(iter, t10_pi_ip_fn, 3);
 151 }
 152
 153 static int t10_pi_type3_verify_crc(struct blk_integrity_iter *iter)
 154 {
 155         return t10_pi_verify(iter, t10_pi_crc_fn, 3);
 156 }
 157
 158 static int t10_pi_type3_verify_ip(struct blk_integrity_iter *iter)
 159 {
 160         return t10_pi_verify(iter, t10_pi_ip_fn, 3);
 161 }
 162
 163 struct blk_integrity t10_pi_type1_crc = {
 164         .name                   = "T10-DIF-TYPE1-CRC",
 165         .generate_fn            = t10_pi_type1_generate_crc,
 166         .verify_fn              = t10_pi_type1_verify_crc,
 167         .tuple_size             = sizeof(struct t10_pi_tuple),
 168         .tag_size               = 0,
 169 };
 170 EXPORT_SYMBOL(t10_pi_type1_crc);
 171
 172 struct blk_integrity t10_pi_type1_ip = {
 173         .name                   = "T10-DIF-TYPE1-IP",
 174         .generate_fn            = t10_pi_type1_generate_ip,
 175         .verify_fn              = t10_pi_type1_verify_ip,
 176         .tuple_size             = sizeof(struct t10_pi_tuple),
 177         .tag_size               = 0,
 178 };
 179 EXPORT_SYMBOL(t10_pi_type1_ip);
 180
 181 struct blk_integrity t10_pi_type3_crc = {
 182         .name                   = "T10-DIF-TYPE3-CRC",
 183         .generate_fn            = t10_pi_type3_generate_crc,
 184         .verify_fn              = t10_pi_type3_verify_crc,
 185         .tuple_size             = sizeof(struct t10_pi_tuple),
 186         .tag_size               = 0,
 187 };
 188 EXPORT_SYMBOL(t10_pi_type3_crc);
 189
 190 struct blk_integrity t10_pi_type3_ip = {
 191         .name                   = "T10-DIF-TYPE3-IP",
 192         .generate_fn            = t10_pi_type3_generate_ip,
 193         .verify_fn              = t10_pi_type3_verify_ip,
 194         .tuple_size             = sizeof(struct t10_pi_tuple),
 195         .tag_size               = 0,
 196 };
 197 EXPORT_SYMBOL(t10_pi_type3_ip);