* Rik Snel | 2007-09-03 23:45:16 [+0200]:
>diff --git a/crypto/xts.c b/crypto/xts.c
>new file mode 100644
>index 0000000..7d9a353
>--- /dev/null
>+++ b/crypto/xts.c
>@@ -0,0 +1,277 @@
>+/* XTS: as defined in IEEE1619/D16
>+ * http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
>+ * (sector sizes which are not a multiple of 16 bytes are,
>+ * however currently unsupported)
>+ *
>+ * Copyright (c) 2007 Rik Snel <[EMAIL PROTECTED]>
>+ *
>+ * Based om ecb.c
>+ * Copyright (c) 2006 Herbert Xu <[EMAIL PROTECTED]>
>+ *
>+ * This program is free software; you can redistribute it and/or modify it
>+ * under the terms of the GNU General Public License as published by the Free
>+ * Software Foundation; either version 2 of the License, or (at your option)
>+ * any later version.
>+ */
>+#include <crypto/algapi.h>
>+#include <linux/err.h>
>+#include <linux/init.h>
>+#include <linux/kernel.h>
>+#include <linux/module.h>
>+#include <linux/scatterlist.h>
>+#include <linux/slab.h>
>+
>+#include <crypto/b128ops.h>
>+#include <crypto/gf128mul.h>
>+
>+struct priv {
>+ struct crypto_cipher *child;
>+ struct crypto_cipher *tweak;
>+};
>+
>+static int setkey(struct crypto_tfm *parent, const u8 *key,
>+ unsigned int keylen)
>+{
>+ struct priv *ctx = crypto_tfm_ctx(parent);
>+ struct crypto_cipher *child = ctx->tweak;
>+ u32 *flags = &parent->crt_flags;
>+ int err;
>+
>+ /* key consists of keys of equal size concatenated, therefore
>+ * the length must be even */
>+ if (keylen % 2) {
>+ /* does anyone read this flag, it is not set if key setup
>+ * fails below (or is it?) */
>+ *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
>+ return -EINVAL;
>+ }
A algo user might read this.
>+
>+ /* we need two cipher instances: one to compute the inital 'tweak'
>+ * by encrypting the IV (usually the 'plain' iv) and the other
>+ * one to encrypt and decrypt the data */
>+
>+ /* tweak cipher, uses Key2 i.e. the second half of *key */
>+ crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
>+ crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
>+ CRYPTO_TFM_REQ_MASK);
>+ if ((err = crypto_cipher_setkey(child, key + keylen/2, keylen/2)))
>+ return err;
why not
err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
if (err)
return err;
>+ crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
>+ CRYPTO_TFM_RES_MASK);
>+
>+ child = ctx->child;
>+
>+ /* data cipher, uses Key1 i.e. the first half of *key */
>+ crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
>+ crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
>+ CRYPTO_TFM_REQ_MASK);
>+ if ((err = crypto_cipher_setkey(child, key, keylen/2)))
...
>+ return err;
>+ crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
>+ CRYPTO_TFM_RES_MASK);
>+
>+ return 0;
>+}
>+
>+struct sinfo {
>+ be128 t;
>+ struct crypto_tfm *tfm;
>+ void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
>+};
>+
>+static inline void xts_round(struct sinfo *s, void *dst, const void *src)
>+{
>+ be128_xor(dst, &s->t, src); /* PP <- T xor P */
>+ s->fn(s->tfm, dst, dst); /* CC <- E(Key1,PP) */
>+ be128_xor(dst, dst, &s->t); /* C <- T xor CC */
>+}
>+
>+static int crypt(struct blkcipher_desc *d,
>+ struct blkcipher_walk *w, struct priv *ctx,
>+ void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
>+ void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
>+{
>+ int err;
>+ unsigned int avail;
>+ const int bs = crypto_cipher_blocksize(ctx->child);
>+ struct sinfo s = {
>+ .tfm = crypto_cipher_tfm(ctx->child),
>+ .fn = fn
>+ };
>+ be128 *iv;
>+ u8 *wsrc;
>+ u8 *wdst;
>+
>+ err = blkcipher_walk_virt(d, w);
>+ if (!(avail = w->nbytes))
...
>+ return err;
>+
>+ wsrc = w->src.virt.addr;
>+ wdst = w->dst.virt.addr;
>+
>+ /* calculate first value of T */
>+ iv = (be128 *)w->iv;
>+ tw(crypto_cipher_tfm(ctx->tweak), (void*)&s.t, w->iv);
>+
>+ goto first;
>+
>+ for (;;) {
>+ do {
>+ gf128mul_x_ble(&s.t, &s.t);
>+
>+first:
why not
int first = 0;
...
do {
if (!first) {
gf128mul_x_ble(&s.t, &s.t);
first = 1;
}
The compiler should generate similar code.
>+ xts_round(&s, wdst, wsrc);
>+
>+ wsrc += bs;
>+ wdst += bs;
>+ } while ((avail -= bs) >= bs);
>+
>+ err = blkcipher_walk_done(d, w, avail);
>+ if (!(avail = w->nbytes))
avail = w->nbytes;
if (!avail)
>+ break;
>+
>+ wsrc = w->src.virt.addr;
>+ wdst = w->dst.virt.addr;
>+ }
>+
>+ return err;
>+}
>+
>+static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
>+ struct scatterlist *src, unsigned int nbytes)
>+{
>+ struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
>+ struct blkcipher_walk w;
>+
>+ blkcipher_walk_init(&w, dst, src, nbytes);
>+ return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
>+ crypto_cipher_alg(ctx->child)->cia_encrypt);
>+}
>+
>+static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
>+ struct scatterlist *src, unsigned int nbytes)
>+{
>+ struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
>+ struct blkcipher_walk w;
>+
>+ blkcipher_walk_init(&w, dst, src, nbytes);
>+ return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
>+ crypto_cipher_alg(ctx->child)->cia_decrypt);
>+}
>+
>+static int init_tfm(struct crypto_tfm *tfm)
>+{
>+ struct crypto_cipher *cipher;
>+ struct crypto_instance *inst = (void *)tfm->__crt_alg;
>+ struct crypto_spawn *spawn = crypto_instance_ctx(inst);
>+ struct priv *ctx = crypto_tfm_ctx(tfm);
>+ u32 *flags = &tfm->crt_flags;
>+
>+ cipher = crypto_spawn_cipher(spawn);
>+ if (IS_ERR(cipher))
>+ return PTR_ERR(cipher);
>+
>+ if (crypto_cipher_blocksize(cipher) != 16) {
>+ *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
>+ return -EINVAL;
>+ }
>+
>+ ctx->child = cipher;
>+
>+ cipher = crypto_spawn_cipher(spawn);
>+ if (IS_ERR(cipher))
>+ return PTR_ERR(cipher);
don't you want to free ctx->child on error?
>+
>+ /* this check isn't really needed */
>+ if (crypto_cipher_blocksize(cipher) != 16) {
>+ *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
>+ return -EINVAL;
>+ }
and here both.
Right now you should get the same algo but I don't thing that a check
will hurt.
>+
>+ ctx->tweak = cipher;
>+
>+ return 0;
>+}
>+
>+static void exit_tfm(struct crypto_tfm *tfm)
>+{
>+ struct priv *ctx = crypto_tfm_ctx(tfm);
>+ crypto_free_cipher(ctx->child);
>+ crypto_free_cipher(ctx->tweak);
>+}
>+
>+static struct crypto_instance *alloc(struct rtattr **tb)
>+{
>+ struct crypto_instance *inst;
>+ struct crypto_alg *alg;
>+ int err;
>+
>+ err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
>+ if (err)
>+ return ERR_PTR(err);
>+
>+ alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
>+ CRYPTO_ALG_TYPE_MASK);
>+ if (IS_ERR(alg))
>+ return ERR_PTR(PTR_ERR(alg));
>+
>+ inst = crypto_alloc_instance("xts", alg);
>+ if (IS_ERR(inst))
>+ goto out_put_alg;
>+
>+ inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
>+ inst->alg.cra_priority = alg->cra_priority;
>+ inst->alg.cra_blocksize = alg->cra_blocksize;
>+
>+ if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
>+ else inst->alg.cra_alignmask = alg->cra_alignmask;
>+ inst->alg.cra_type = &crypto_blkcipher_type;
>+
>+ if (!(alg->cra_blocksize % 4))
>+ inst->alg.cra_alignmask |= 3;
please do
if (a)
do_on_a();
else
do_on_b();
besides that, what are you trying to do? The if() makes sure that the
alignmask is atleast 7 (0b111). And then, depending on the block size
you might set the lower two bits (3 is 0b11) which are allready set.
>+ inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
>+ inst->alg.cra_blkcipher.min_keysize = 2*alg->cra_cipher.cia_min_keysize;
>+ inst->alg.cra_blkcipher.max_keysize = 2*alg->cra_cipher.cia_max_keysize;
a space between the operator might not be a bad idea.
>+
>+ inst->alg.cra_ctxsize = sizeof(struct priv);
>+
>+ inst->alg.cra_init = init_tfm;
>+ inst->alg.cra_exit = exit_tfm;
>+
>+ inst->alg.cra_blkcipher.setkey = setkey;
>+ inst->alg.cra_blkcipher.encrypt = encrypt;
>+ inst->alg.cra_blkcipher.decrypt = decrypt;
>+
>+out_put_alg:
>+ crypto_mod_put(alg);
>+ return inst;
>+}
>+
>+static void free(struct crypto_instance *inst)
>+{
>+ crypto_drop_spawn(crypto_instance_ctx(inst));
>+ kfree(inst);
>+}
>+
>+static struct crypto_template crypto_tmpl = {
>+ .name = "xts",
>+ .alloc = alloc,
>+ .free = free,
>+ .module = THIS_MODULE,
>+};
>+
>+static int __init crypto_module_init(void)
>+{
>+ return crypto_register_template(&crypto_tmpl);
>+}
>+
>+static void __exit crypto_module_exit(void)
>+{
>+ crypto_unregister_template(&crypto_tmpl);
>+}
>+
>+module_init(crypto_module_init);
>+module_exit(crypto_module_exit);
>+
>+MODULE_LICENSE("GPL");
>+MODULE_DESCRIPTION("XTS block cipher mode");
The other things are looking fine to me. You might want to consider
using ./scripts/checkpatch.pl on your patch the next time :)
Sebastian
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