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 const __be16 APP_ESCAPE = (__force __be16) 0xffff;
 32static const __be32 REF_ESCAPE = (__force __be32) 0xffffffff;
 33
 34static __be16 t10_pi_crc_fn(void *data, unsigned int len)
 35{
 36	return cpu_to_be16(crc_t10dif(data, len));
 37}
 38
 39static __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 */
 49static 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
 73static 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
114next:
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
123static 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
128static 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
133static 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
138static 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
143static 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
148static 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
153static 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
158static 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
163struct blk_integrity_profile 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};
168EXPORT_SYMBOL(t10_pi_type1_crc);
169
170struct blk_integrity_profile t10_pi_type1_ip = {
171	.name			= "T10-DIF-TYPE1-IP",
172	.generate_fn		= t10_pi_type1_generate_ip,
173	.verify_fn		= t10_pi_type1_verify_ip,
174};
175EXPORT_SYMBOL(t10_pi_type1_ip);
176
177struct blk_integrity_profile t10_pi_type3_crc = {
178	.name			= "T10-DIF-TYPE3-CRC",
179	.generate_fn		= t10_pi_type3_generate_crc,
180	.verify_fn		= t10_pi_type3_verify_crc,
181};
182EXPORT_SYMBOL(t10_pi_type3_crc);
183
184struct blk_integrity_profile t10_pi_type3_ip = {
185	.name			= "T10-DIF-TYPE3-IP",
186	.generate_fn		= t10_pi_type3_generate_ip,
187	.verify_fn		= t10_pi_type3_verify_ip,
188};
189EXPORT_SYMBOL(t10_pi_type3_ip);