Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 1 | /* |
| 2 | * CTR: Counter mode |
| 3 | * |
| 4 | * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify it |
| 7 | * under the terms of the GNU General Public License as published by the Free |
| 8 | * Software Foundation; either version 2 of the License, or (at your option) |
| 9 | * any later version. |
| 10 | * |
| 11 | */ |
| 12 | |
| 13 | #include <crypto/algapi.h> |
| 14 | #include <linux/err.h> |
| 15 | #include <linux/init.h> |
| 16 | #include <linux/kernel.h> |
| 17 | #include <linux/module.h> |
| 18 | #include <linux/random.h> |
| 19 | #include <linux/scatterlist.h> |
| 20 | #include <linux/slab.h> |
| 21 | |
| 22 | struct ctr_instance_ctx { |
| 23 | struct crypto_spawn alg; |
| 24 | unsigned int noncesize; |
| 25 | unsigned int ivsize; |
Joy Latten | 41fdab3 | 2007-11-07 22:59:47 +0800 | [diff] [blame] | 26 | unsigned int countersize; |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 27 | }; |
| 28 | |
| 29 | struct crypto_ctr_ctx { |
| 30 | struct crypto_cipher *child; |
| 31 | u8 *nonce; |
| 32 | }; |
| 33 | |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 34 | static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key, |
| 35 | unsigned int keylen) |
| 36 | { |
| 37 | struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent); |
| 38 | struct crypto_cipher *child = ctx->child; |
| 39 | struct ctr_instance_ctx *ictx = |
| 40 | crypto_instance_ctx(crypto_tfm_alg_instance(parent)); |
| 41 | unsigned int noncelen = ictx->noncesize; |
| 42 | int err = 0; |
| 43 | |
| 44 | /* the nonce is stored in bytes at end of key */ |
| 45 | if (keylen < noncelen) |
| 46 | return -EINVAL; |
| 47 | |
| 48 | memcpy(ctx->nonce, key + (keylen - noncelen), noncelen); |
| 49 | |
| 50 | keylen -= noncelen; |
| 51 | |
| 52 | crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); |
| 53 | crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) & |
| 54 | CRYPTO_TFM_REQ_MASK); |
| 55 | err = crypto_cipher_setkey(child, key, keylen); |
| 56 | crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & |
| 57 | CRYPTO_TFM_RES_MASK); |
| 58 | |
| 59 | return err; |
| 60 | } |
| 61 | |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 62 | static void crypto_ctr_crypt_final(struct blkcipher_walk *walk, |
| 63 | struct crypto_cipher *tfm, u8 *ctrblk, |
| 64 | unsigned int countersize) |
| 65 | { |
| 66 | unsigned int bsize = crypto_cipher_blocksize(tfm); |
| 67 | u8 *keystream = ctrblk + bsize; |
| 68 | u8 *src = walk->src.virt.addr; |
| 69 | u8 *dst = walk->dst.virt.addr; |
| 70 | unsigned int nbytes = walk->nbytes; |
| 71 | |
| 72 | crypto_cipher_encrypt_one(tfm, keystream, ctrblk); |
| 73 | crypto_xor(keystream, src, nbytes); |
| 74 | memcpy(dst, keystream, nbytes); |
| 75 | } |
| 76 | |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 77 | static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk, |
| 78 | struct crypto_cipher *tfm, u8 *ctrblk, |
| 79 | unsigned int countersize) |
| 80 | { |
| 81 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = |
| 82 | crypto_cipher_alg(tfm)->cia_encrypt; |
| 83 | unsigned int bsize = crypto_cipher_blocksize(tfm); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 84 | u8 *src = walk->src.virt.addr; |
| 85 | u8 *dst = walk->dst.virt.addr; |
| 86 | unsigned int nbytes = walk->nbytes; |
| 87 | |
| 88 | do { |
| 89 | /* create keystream */ |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 90 | fn(crypto_cipher_tfm(tfm), dst, ctrblk); |
| 91 | crypto_xor(dst, src, bsize); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 92 | |
| 93 | /* increment counter in counterblock */ |
Herbert Xu | 3f8214e | 2007-11-20 20:32:56 +0800 | [diff] [blame] | 94 | crypto_inc(ctrblk + bsize - countersize, countersize); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 95 | |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 96 | src += bsize; |
| 97 | dst += bsize; |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 98 | } while ((nbytes -= bsize) >= bsize); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 99 | |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 100 | return nbytes; |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 101 | } |
| 102 | |
| 103 | static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk, |
| 104 | struct crypto_cipher *tfm, u8 *ctrblk, |
| 105 | unsigned int countersize) |
| 106 | { |
| 107 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = |
| 108 | crypto_cipher_alg(tfm)->cia_encrypt; |
| 109 | unsigned int bsize = crypto_cipher_blocksize(tfm); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 110 | unsigned int nbytes = walk->nbytes; |
| 111 | u8 *src = walk->src.virt.addr; |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 112 | u8 *keystream = ctrblk + bsize; |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 113 | |
| 114 | do { |
| 115 | /* create keystream */ |
| 116 | fn(crypto_cipher_tfm(tfm), keystream, ctrblk); |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 117 | crypto_xor(src, keystream, bsize); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 118 | |
| 119 | /* increment counter in counterblock */ |
Herbert Xu | 3f8214e | 2007-11-20 20:32:56 +0800 | [diff] [blame] | 120 | crypto_inc(ctrblk + bsize - countersize, countersize); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 121 | |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 122 | src += bsize; |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 123 | } while ((nbytes -= bsize) >= bsize); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 124 | |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 125 | return nbytes; |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 126 | } |
| 127 | |
| 128 | static int crypto_ctr_crypt(struct blkcipher_desc *desc, |
| 129 | struct scatterlist *dst, struct scatterlist *src, |
| 130 | unsigned int nbytes) |
| 131 | { |
| 132 | struct blkcipher_walk walk; |
| 133 | struct crypto_blkcipher *tfm = desc->tfm; |
| 134 | struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm); |
| 135 | struct crypto_cipher *child = ctx->child; |
| 136 | unsigned int bsize = crypto_cipher_blocksize(child); |
| 137 | struct ctr_instance_ctx *ictx = |
| 138 | crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base)); |
Herbert Xu | 3f8214e | 2007-11-20 20:32:56 +0800 | [diff] [blame] | 139 | unsigned long alignmask = crypto_cipher_alignmask(child) | |
| 140 | (__alignof__(u32) - 1); |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 141 | u8 cblk[bsize * 2 + alignmask]; |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 142 | u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 143 | int err; |
| 144 | |
| 145 | blkcipher_walk_init(&walk, dst, src, nbytes); |
| 146 | err = blkcipher_walk_virt_block(desc, &walk, bsize); |
| 147 | |
| 148 | /* set up counter block */ |
| 149 | memset(counterblk, 0 , bsize); |
| 150 | memcpy(counterblk, ctx->nonce, ictx->noncesize); |
| 151 | memcpy(counterblk + ictx->noncesize, walk.iv, ictx->ivsize); |
| 152 | |
| 153 | /* initialize counter portion of counter block */ |
Herbert Xu | 3f8214e | 2007-11-20 20:32:56 +0800 | [diff] [blame] | 154 | crypto_inc(counterblk + bsize - ictx->countersize, ictx->countersize); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 155 | |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 156 | while (walk.nbytes >= bsize) { |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 157 | if (walk.src.virt.addr == walk.dst.virt.addr) |
| 158 | nbytes = crypto_ctr_crypt_inplace(&walk, child, |
| 159 | counterblk, |
Joy Latten | 41fdab3 | 2007-11-07 22:59:47 +0800 | [diff] [blame] | 160 | ictx->countersize); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 161 | else |
| 162 | nbytes = crypto_ctr_crypt_segment(&walk, child, |
| 163 | counterblk, |
Joy Latten | 41fdab3 | 2007-11-07 22:59:47 +0800 | [diff] [blame] | 164 | ictx->countersize); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 165 | |
| 166 | err = blkcipher_walk_done(desc, &walk, nbytes); |
| 167 | } |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 168 | |
| 169 | if (walk.nbytes) { |
| 170 | crypto_ctr_crypt_final(&walk, child, counterblk, |
| 171 | ictx->countersize); |
| 172 | err = blkcipher_walk_done(desc, &walk, 0); |
| 173 | } |
| 174 | |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 175 | return err; |
| 176 | } |
| 177 | |
| 178 | static int crypto_ctr_init_tfm(struct crypto_tfm *tfm) |
| 179 | { |
| 180 | struct crypto_instance *inst = (void *)tfm->__crt_alg; |
| 181 | struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst); |
| 182 | struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); |
| 183 | struct crypto_cipher *cipher; |
| 184 | |
| 185 | ctx->nonce = kzalloc(ictx->noncesize, GFP_KERNEL); |
| 186 | if (!ctx->nonce) |
| 187 | return -ENOMEM; |
| 188 | |
| 189 | cipher = crypto_spawn_cipher(&ictx->alg); |
| 190 | if (IS_ERR(cipher)) |
| 191 | return PTR_ERR(cipher); |
| 192 | |
| 193 | ctx->child = cipher; |
| 194 | |
| 195 | return 0; |
| 196 | } |
| 197 | |
| 198 | static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm) |
| 199 | { |
| 200 | struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); |
| 201 | |
| 202 | kfree(ctx->nonce); |
| 203 | crypto_free_cipher(ctx->child); |
| 204 | } |
| 205 | |
| 206 | static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb) |
| 207 | { |
| 208 | struct crypto_instance *inst; |
| 209 | struct crypto_alg *alg; |
| 210 | struct ctr_instance_ctx *ictx; |
| 211 | unsigned int noncesize; |
| 212 | unsigned int ivsize; |
Joy Latten | 41fdab3 | 2007-11-07 22:59:47 +0800 | [diff] [blame] | 213 | unsigned int countersize; |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 214 | int err; |
| 215 | |
| 216 | err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); |
| 217 | if (err) |
| 218 | return ERR_PTR(err); |
| 219 | |
| 220 | alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, |
| 221 | CRYPTO_ALG_TYPE_MASK); |
| 222 | if (IS_ERR(alg)) |
| 223 | return ERR_PTR(PTR_ERR(alg)); |
| 224 | |
| 225 | err = crypto_attr_u32(tb[2], &noncesize); |
| 226 | if (err) |
| 227 | goto out_put_alg; |
| 228 | |
| 229 | err = crypto_attr_u32(tb[3], &ivsize); |
| 230 | if (err) |
| 231 | goto out_put_alg; |
| 232 | |
Joy Latten | 41fdab3 | 2007-11-07 22:59:47 +0800 | [diff] [blame] | 233 | err = crypto_attr_u32(tb[4], &countersize); |
| 234 | if (err) |
| 235 | goto out_put_alg; |
| 236 | |
| 237 | /* verify size of nonce + iv + counter |
| 238 | * counter must be >= 4 bytes. |
| 239 | */ |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 240 | err = -EINVAL; |
Joy Latten | 41fdab3 | 2007-11-07 22:59:47 +0800 | [diff] [blame] | 241 | if (((noncesize + ivsize + countersize) < alg->cra_blocksize) || |
| 242 | ((noncesize + ivsize) > alg->cra_blocksize) || |
| 243 | (countersize > alg->cra_blocksize) || (countersize < 4)) |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 244 | goto out_put_alg; |
| 245 | |
Herbert Xu | 3f8214e | 2007-11-20 20:32:56 +0800 | [diff] [blame] | 246 | /* If this is false we'd fail the alignment of crypto_inc. */ |
| 247 | if ((alg->cra_blocksize - countersize) % 4) |
| 248 | goto out_put_alg; |
| 249 | |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 250 | inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL); |
| 251 | err = -ENOMEM; |
| 252 | if (!inst) |
| 253 | goto out_put_alg; |
| 254 | |
| 255 | err = -ENAMETOOLONG; |
| 256 | if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME, |
Joy Latten | 41fdab3 | 2007-11-07 22:59:47 +0800 | [diff] [blame] | 257 | "ctr(%s,%u,%u,%u)", alg->cra_name, noncesize, |
| 258 | ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) { |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 259 | goto err_free_inst; |
| 260 | } |
| 261 | |
| 262 | if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME, |
Joy Latten | 41fdab3 | 2007-11-07 22:59:47 +0800 | [diff] [blame] | 263 | "ctr(%s,%u,%u,%u)", alg->cra_driver_name, noncesize, |
| 264 | ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) { |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 265 | goto err_free_inst; |
| 266 | } |
| 267 | |
| 268 | ictx = crypto_instance_ctx(inst); |
| 269 | ictx->noncesize = noncesize; |
| 270 | ictx->ivsize = ivsize; |
Joy Latten | 41fdab3 | 2007-11-07 22:59:47 +0800 | [diff] [blame] | 271 | ictx->countersize = countersize; |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 272 | |
| 273 | err = crypto_init_spawn(&ictx->alg, alg, inst, |
| 274 | CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC); |
| 275 | if (err) |
| 276 | goto err_free_inst; |
| 277 | |
| 278 | err = 0; |
| 279 | inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; |
| 280 | inst->alg.cra_priority = alg->cra_priority; |
| 281 | inst->alg.cra_blocksize = 1; |
Herbert Xu | 0971eb0 | 2007-11-30 00:23:53 +1100 | [diff] [blame] | 282 | inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1); |
Joy Latten | 23e353c | 2007-10-23 08:50:32 +0800 | [diff] [blame] | 283 | inst->alg.cra_type = &crypto_blkcipher_type; |
| 284 | |
| 285 | inst->alg.cra_blkcipher.ivsize = ivsize; |
| 286 | inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize |
| 287 | + noncesize; |
| 288 | inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize |
| 289 | + noncesize; |
| 290 | |
| 291 | inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx); |
| 292 | |
| 293 | inst->alg.cra_init = crypto_ctr_init_tfm; |
| 294 | inst->alg.cra_exit = crypto_ctr_exit_tfm; |
| 295 | |
| 296 | inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey; |
| 297 | inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt; |
| 298 | inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt; |
| 299 | |
| 300 | err_free_inst: |
| 301 | if (err) |
| 302 | kfree(inst); |
| 303 | |
| 304 | out_put_alg: |
| 305 | crypto_mod_put(alg); |
| 306 | |
| 307 | if (err) |
| 308 | inst = ERR_PTR(err); |
| 309 | |
| 310 | return inst; |
| 311 | } |
| 312 | |
| 313 | static void crypto_ctr_free(struct crypto_instance *inst) |
| 314 | { |
| 315 | struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst); |
| 316 | |
| 317 | crypto_drop_spawn(&ictx->alg); |
| 318 | kfree(inst); |
| 319 | } |
| 320 | |
| 321 | static struct crypto_template crypto_ctr_tmpl = { |
| 322 | .name = "ctr", |
| 323 | .alloc = crypto_ctr_alloc, |
| 324 | .free = crypto_ctr_free, |
| 325 | .module = THIS_MODULE, |
| 326 | }; |
| 327 | |
| 328 | static int __init crypto_ctr_module_init(void) |
| 329 | { |
| 330 | return crypto_register_template(&crypto_ctr_tmpl); |
| 331 | } |
| 332 | |
| 333 | static void __exit crypto_ctr_module_exit(void) |
| 334 | { |
| 335 | crypto_unregister_template(&crypto_ctr_tmpl); |
| 336 | } |
| 337 | |
| 338 | module_init(crypto_ctr_module_init); |
| 339 | module_exit(crypto_ctr_module_exit); |
| 340 | |
| 341 | MODULE_LICENSE("GPL"); |
| 342 | MODULE_DESCRIPTION("CTR Counter block mode"); |