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
 29typedef __be16 (csum_fn) (void *, unsigned int);
 30
 31static __be16 t10_pi_crc_fn(void *data, unsigned int len)
 32{
 33	return cpu_to_be16(crc_t10dif(data, len));
 34}
 35
 36static __be16 t10_pi_ip_fn(void *data, unsigned int len)
 37{
 38	return (__force __be16)ip_compute_csum(data, len);
 39}
 40
 41/*
 42 * Type 1 and Type 2 protection use the same format: 16 bit guard tag,
 43 * 16 bit app tag, 32 bit reference tag. Type 3 does not define the ref
 44 * tag.
 45 */
 46static blk_status_t t10_pi_generate(struct blk_integrity_iter *iter,
 47		csum_fn *fn, unsigned int type)
 48{
 49	unsigned int i;
 50
 51	for (i = 0 ; i < iter->data_size ; i += iter->interval) {
 52		struct t10_pi_tuple *pi = iter->prot_buf;
 53
 54		pi->guard_tag = fn(iter->data_buf, iter->interval);
 55		pi->app_tag = 0;
 56
 57		if (type == 1)
 58			pi->ref_tag = cpu_to_be32(lower_32_bits(iter->seed));
 59		else
 60			pi->ref_tag = 0;
 61
 62		iter->data_buf += iter->interval;
 63		iter->prot_buf += sizeof(struct t10_pi_tuple);
 64		iter->seed++;
 65	}
 66
 67	return BLK_STS_OK;
 68}
 69
 70static blk_status_t t10_pi_verify(struct blk_integrity_iter *iter,
 71		csum_fn *fn, unsigned int type)
 72{
 73	unsigned int i;
 74
 75	for (i = 0 ; i < iter->data_size ; i += iter->interval) {
 76		struct t10_pi_tuple *pi = iter->prot_buf;
 77		__be16 csum;
 78
 79		switch (type) {
 80		case 1:
 81		case 2:
 82			if (pi->app_tag == T10_PI_APP_ESCAPE)
 83				goto next;
 84
 85			if (be32_to_cpu(pi->ref_tag) !=
 86			    lower_32_bits(iter->seed)) {
 87				pr_err("%s: ref tag error at location %llu " \
 88				       "(rcvd %u)\n", iter->disk_name,
 89				       (unsigned long long)
 90				       iter->seed, be32_to_cpu(pi->ref_tag));
 91				return BLK_STS_PROTECTION;
 92			}
 93			break;
 94		case 3:
 95			if (pi->app_tag == T10_PI_APP_ESCAPE &&
 96			    pi->ref_tag == T10_PI_REF_ESCAPE)
 97				goto next;
 98			break;
 99		}
100
101		csum = fn(iter->data_buf, iter->interval);
102
103		if (pi->guard_tag != csum) {
104			pr_err("%s: guard tag error at sector %llu " \
105			       "(rcvd %04x, want %04x)\n", iter->disk_name,
106			       (unsigned long long)iter->seed,
107			       be16_to_cpu(pi->guard_tag), be16_to_cpu(csum));
108			return BLK_STS_PROTECTION;
109		}
110
111next:
112		iter->data_buf += iter->interval;
113		iter->prot_buf += sizeof(struct t10_pi_tuple);
114		iter->seed++;
115	}
116
117	return BLK_STS_OK;
118}
119
120static blk_status_t t10_pi_type1_generate_crc(struct blk_integrity_iter *iter)
121{
122	return t10_pi_generate(iter, t10_pi_crc_fn, 1);
123}
124
125static blk_status_t t10_pi_type1_generate_ip(struct blk_integrity_iter *iter)
126{
127	return t10_pi_generate(iter, t10_pi_ip_fn, 1);
128}
129
130static blk_status_t t10_pi_type1_verify_crc(struct blk_integrity_iter *iter)
131{
132	return t10_pi_verify(iter, t10_pi_crc_fn, 1);
133}
134
135static blk_status_t t10_pi_type1_verify_ip(struct blk_integrity_iter *iter)
136{
137	return t10_pi_verify(iter, t10_pi_ip_fn, 1);
138}
139
140static blk_status_t t10_pi_type3_generate_crc(struct blk_integrity_iter *iter)
141{
142	return t10_pi_generate(iter, t10_pi_crc_fn, 3);
143}
144
145static blk_status_t t10_pi_type3_generate_ip(struct blk_integrity_iter *iter)
146{
147	return t10_pi_generate(iter, t10_pi_ip_fn, 3);
148}
149
150static blk_status_t t10_pi_type3_verify_crc(struct blk_integrity_iter *iter)
151{
152	return t10_pi_verify(iter, t10_pi_crc_fn, 3);
153}
154
155static blk_status_t t10_pi_type3_verify_ip(struct blk_integrity_iter *iter)
156{
157	return t10_pi_verify(iter, t10_pi_ip_fn, 3);
158}
159
160const struct blk_integrity_profile t10_pi_type1_crc = {
161	.name			= "T10-DIF-TYPE1-CRC",
162	.generate_fn		= t10_pi_type1_generate_crc,
163	.verify_fn		= t10_pi_type1_verify_crc,
164};
165EXPORT_SYMBOL(t10_pi_type1_crc);
166
167const struct blk_integrity_profile t10_pi_type1_ip = {
168	.name			= "T10-DIF-TYPE1-IP",
169	.generate_fn		= t10_pi_type1_generate_ip,
170	.verify_fn		= t10_pi_type1_verify_ip,
171};
172EXPORT_SYMBOL(t10_pi_type1_ip);
173
174const struct blk_integrity_profile t10_pi_type3_crc = {
175	.name			= "T10-DIF-TYPE3-CRC",
176	.generate_fn		= t10_pi_type3_generate_crc,
177	.verify_fn		= t10_pi_type3_verify_crc,
178};
179EXPORT_SYMBOL(t10_pi_type3_crc);
180
181const struct blk_integrity_profile t10_pi_type3_ip = {
182	.name			= "T10-DIF-TYPE3-IP",
183	.generate_fn		= t10_pi_type3_generate_ip,
184	.verify_fn		= t10_pi_type3_verify_ip,
185};
186EXPORT_SYMBOL(t10_pi_type3_ip);