1/**
2 * GHASH routines supporting VMX instructions on the Power 8
3 *
4 * Copyright (C) 2015 International Business Machines Inc.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; version 2 only.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18 *
19 * Author: Marcelo Henrique Cerri <mhcerri@br.ibm.com>
20 */
21
22#include <linux/types.h>
23#include <linux/err.h>
24#include <linux/crypto.h>
25#include <linux/delay.h>
26#include <linux/hardirq.h>
27#include <asm/switch_to.h>
28#include <crypto/aes.h>
29#include <crypto/scatterwalk.h>
30#include <crypto/internal/hash.h>
31#include <crypto/b128ops.h>
32
33#define IN_INTERRUPT in_interrupt()
34
35#define GHASH_BLOCK_SIZE (16)
36#define GHASH_DIGEST_SIZE (16)
37#define GHASH_KEY_LEN (16)
38
39void gcm_init_p8(u128 htable[16], const u64 Xi[2]);
40void gcm_gmult_p8(u64 Xi[2], const u128 htable[16]);
41void gcm_ghash_p8(u64 Xi[2], const u128 htable[16],
42        const u8 *in,size_t len);
43
44struct p8_ghash_ctx {
45    u128 htable[16];
46    struct crypto_shash *fallback;
47};
48
49struct p8_ghash_desc_ctx {
50    u64 shash[2];
51    u8 buffer[GHASH_DIGEST_SIZE];
52    int bytes;
53    struct shash_desc fallback_desc;
54};
55
56static int p8_ghash_init_tfm(struct crypto_tfm *tfm)
57{
58    const char *alg;
59    struct crypto_shash *fallback;
60    struct crypto_shash *shash_tfm = __crypto_shash_cast(tfm);
61    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
62
63    if (!(alg = crypto_tfm_alg_name(tfm))) {
64        printk(KERN_ERR "Failed to get algorithm name.\n");
65        return -ENOENT;
66    }
67
68    fallback = crypto_alloc_shash(alg, 0 ,CRYPTO_ALG_NEED_FALLBACK);
69    if (IS_ERR(fallback)) {
70        printk(KERN_ERR "Failed to allocate transformation for '%s': %ld\n",
71                alg, PTR_ERR(fallback));
72        return PTR_ERR(fallback);
73    }
74    printk(KERN_INFO "Using '%s' as fallback implementation.\n",
75            crypto_tfm_alg_driver_name(crypto_shash_tfm(fallback)));
76
77    crypto_shash_set_flags(fallback,
78            crypto_shash_get_flags((struct crypto_shash *) tfm));
79    ctx->fallback = fallback;
80
81    shash_tfm->descsize = sizeof(struct p8_ghash_desc_ctx)
82        + crypto_shash_descsize(fallback);
83
84    return 0;
85}
86
87static void p8_ghash_exit_tfm(struct crypto_tfm *tfm)
88{
89    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
90
91    if (ctx->fallback) {
92        crypto_free_shash(ctx->fallback);
93        ctx->fallback = NULL;
94    }
95}
96
97static int p8_ghash_init(struct shash_desc *desc)
98{
99    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
100    struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
101
102    dctx->bytes = 0;
103    memset(dctx->shash, 0, GHASH_DIGEST_SIZE);
104    dctx->fallback_desc.tfm = ctx->fallback;
105    dctx->fallback_desc.flags = desc->flags;
106    return crypto_shash_init(&dctx->fallback_desc);
107}
108
109static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
110    unsigned int keylen)
111{
112    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(tfm));
113
114    if (keylen != GHASH_KEY_LEN)
115        return -EINVAL;
116
117    pagefault_disable();
118    enable_kernel_altivec();
119    enable_kernel_vsx();
120    enable_kernel_fp();
121    gcm_init_p8(ctx->htable, (const u64 *) key);
122    pagefault_enable();
123    return crypto_shash_setkey(ctx->fallback, key, keylen);
124}
125
126static int p8_ghash_update(struct shash_desc *desc,
127        const u8 *src, unsigned int srclen)
128{
129    unsigned int len;
130    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
131    struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
132
133    if (IN_INTERRUPT) {
134        return crypto_shash_update(&dctx->fallback_desc, src, srclen);
135    } else {
136        if (dctx->bytes) {
137            if (dctx->bytes + srclen < GHASH_DIGEST_SIZE) {
138                memcpy(dctx->buffer + dctx->bytes, src, srclen);
139                dctx->bytes += srclen;
140                return 0;
141            }
142            memcpy(dctx->buffer + dctx->bytes, src,
143                    GHASH_DIGEST_SIZE - dctx->bytes);
144            pagefault_disable();
145            enable_kernel_altivec();
146            enable_kernel_vsx();
147            enable_kernel_fp();
148            gcm_ghash_p8(dctx->shash, ctx->htable, dctx->buffer,
149                    GHASH_DIGEST_SIZE);
150            pagefault_enable();
151            src += GHASH_DIGEST_SIZE - dctx->bytes;
152            srclen -= GHASH_DIGEST_SIZE - dctx->bytes;
153            dctx->bytes = 0;
154        }
155        len = srclen & ~(GHASH_DIGEST_SIZE - 1);
156        if (len) {
157            pagefault_disable();
158            enable_kernel_altivec();
159            enable_kernel_vsx();
160            enable_kernel_fp();
161            gcm_ghash_p8(dctx->shash, ctx->htable, src, len);
162            pagefault_enable();
163            src += len;
164            srclen -= len;
165        }
166        if (srclen) {
167            memcpy(dctx->buffer, src, srclen);
168            dctx->bytes = srclen;
169        }
170        return 0;
171    }
172}
173
174static int p8_ghash_final(struct shash_desc *desc, u8 *out)
175{
176    int i;
177    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
178    struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
179
180    if (IN_INTERRUPT) {
181        return crypto_shash_final(&dctx->fallback_desc, out);
182    } else {
183        if (dctx->bytes) {
184            for (i = dctx->bytes; i < GHASH_DIGEST_SIZE; i++)
185                dctx->buffer[i] = 0;
186            pagefault_disable();
187            enable_kernel_altivec();
188            enable_kernel_vsx();
189            enable_kernel_fp();
190            gcm_ghash_p8(dctx->shash, ctx->htable, dctx->buffer,
191                    GHASH_DIGEST_SIZE);
192            pagefault_enable();
193            dctx->bytes = 0;
194        }
195        memcpy(out, dctx->shash, GHASH_DIGEST_SIZE);
196        return 0;
197    }
198}
199
200struct shash_alg p8_ghash_alg = {
201    .digestsize = GHASH_DIGEST_SIZE,
202    .init       = p8_ghash_init,
203    .update     = p8_ghash_update,
204    .final      = p8_ghash_final,
205    .setkey     = p8_ghash_setkey,
206    .descsize   = sizeof(struct p8_ghash_desc_ctx),
207    .base       = {
208        .cra_name = "ghash",
209        .cra_driver_name = "p8_ghash",
210        .cra_priority = 1000,
211        .cra_flags = CRYPTO_ALG_TYPE_SHASH | CRYPTO_ALG_NEED_FALLBACK,
212        .cra_blocksize = GHASH_BLOCK_SIZE,
213        .cra_ctxsize = sizeof(struct p8_ghash_ctx),
214        .cra_module = THIS_MODULE,
215        .cra_init = p8_ghash_init_tfm,
216        .cra_exit = p8_ghash_exit_tfm,
217    },
218};
219