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 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};
170EXPORT_SYMBOL(t10_pi_type1_crc);
171
172struct 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};
179EXPORT_SYMBOL(t10_pi_type1_ip);
180
181struct 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};
188EXPORT_SYMBOL(t10_pi_type3_crc);
189
190struct 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};
197EXPORT_SYMBOL(t10_pi_type3_ip);
198