* rfc3962 includes errata information in its Appendix A.
*/
-#include <crypto/algapi.h>
+#include <crypto/internal/skcipher.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/slab.h>
struct crypto_cts_ctx {
- struct crypto_blkcipher *child;
+ struct crypto_skcipher *child;
};
-static int crypto_cts_setkey(struct crypto_tfm *parent, const u8 *key,
- unsigned int keylen)
+struct crypto_cts_reqctx {
+ struct scatterlist sg[2];
+ unsigned offset;
+ struct skcipher_request subreq;
+};
+
+static inline u8 *crypto_cts_reqctx_space(struct skcipher_request *req)
{
- struct crypto_cts_ctx *ctx = crypto_tfm_ctx(parent);
- struct crypto_blkcipher *child = ctx->child;
- int err;
+ struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
+ struct crypto_skcipher *child = ctx->child;
- crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
- crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) &
- CRYPTO_TFM_REQ_MASK);
- err = crypto_blkcipher_setkey(child, key, keylen);
- crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) &
- CRYPTO_TFM_RES_MASK);
- return err;
+ return PTR_ALIGN((u8 *)(rctx + 1) + crypto_skcipher_reqsize(child),
+ crypto_skcipher_alignmask(tfm) + 1);
}
-static int cts_cbc_encrypt(struct crypto_cts_ctx *ctx,
- struct blkcipher_desc *desc,
- struct scatterlist *dst,
- struct scatterlist *src,
- unsigned int offset,
- unsigned int nbytes)
+static int crypto_cts_setkey(struct crypto_skcipher *parent, const u8 *key,
+ unsigned int keylen)
{
- int bsize = crypto_blkcipher_blocksize(desc->tfm);
- u8 tmp[bsize], tmp2[bsize];
- struct blkcipher_desc lcldesc;
- struct scatterlist sgsrc[1], sgdst[1];
- int lastn = nbytes - bsize;
- u8 iv[bsize];
- u8 s[bsize * 2], d[bsize * 2];
+ struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(parent);
+ struct crypto_skcipher *child = ctx->child;
int err;
- if (lastn < 0)
- return -EINVAL;
+ crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
+ crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
+ CRYPTO_TFM_REQ_MASK);
+ err = crypto_skcipher_setkey(child, key, keylen);
+ crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
+ CRYPTO_TFM_RES_MASK);
+ return err;
+}
- sg_init_table(sgsrc, 1);
- sg_init_table(sgdst, 1);
+static void cts_cbc_crypt_done(struct crypto_async_request *areq, int err)
+{
+ struct skcipher_request *req = areq->data;
- memset(s, 0, sizeof(s));
- scatterwalk_map_and_copy(s, src, offset, nbytes, 0);
+ if (err == -EINPROGRESS)
+ return;
- memcpy(iv, desc->info, bsize);
+ skcipher_request_complete(req, err);
+}
- lcldesc.tfm = ctx->child;
- lcldesc.info = iv;
- lcldesc.flags = desc->flags;
+static int cts_cbc_encrypt(struct skcipher_request *req)
+{
+ struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct skcipher_request *subreq = &rctx->subreq;
+ int bsize = crypto_skcipher_blocksize(tfm);
+ u8 d[bsize * 2] __attribute__ ((aligned(__alignof__(u32))));
+ struct scatterlist *sg;
+ unsigned int offset;
+ int lastn;
+
+ offset = rctx->offset;
+ lastn = req->cryptlen - offset;
+
+ sg = scatterwalk_ffwd(rctx->sg, req->dst, offset - bsize);
+ scatterwalk_map_and_copy(d + bsize, sg, 0, bsize, 0);
+
+ memset(d, 0, bsize);
+ scatterwalk_map_and_copy(d, req->src, offset, lastn, 0);
+
+ scatterwalk_map_and_copy(d, sg, 0, bsize + lastn, 1);
+ memzero_explicit(d, sizeof(d));
+
+ skcipher_request_set_callback(subreq, req->base.flags &
+ CRYPTO_TFM_REQ_MAY_BACKLOG,
+ cts_cbc_crypt_done, req);
+ skcipher_request_set_crypt(subreq, sg, sg, bsize, req->iv);
+ return crypto_skcipher_encrypt(subreq);
+}
- sg_set_buf(&sgsrc[0], s, bsize);
- sg_set_buf(&sgdst[0], tmp, bsize);
- err = crypto_blkcipher_encrypt_iv(&lcldesc, sgdst, sgsrc, bsize);
+static void crypto_cts_encrypt_done(struct crypto_async_request *areq, int err)
+{
+ struct skcipher_request *req = areq->data;
- memcpy(d + bsize, tmp, lastn);
+ if (err)
+ goto out;
- lcldesc.info = tmp;
+ err = cts_cbc_encrypt(req);
+ if (err == -EINPROGRESS ||
+ (err == -EBUSY && req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
+ return;
- sg_set_buf(&sgsrc[0], s + bsize, bsize);
- sg_set_buf(&sgdst[0], tmp2, bsize);
- err = crypto_blkcipher_encrypt_iv(&lcldesc, sgdst, sgsrc, bsize);
+out:
+ skcipher_request_complete(req, err);
+}
- memcpy(d, tmp2, bsize);
+static int crypto_cts_encrypt(struct skcipher_request *req)
+{
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
+ struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
+ struct skcipher_request *subreq = &rctx->subreq;
+ int bsize = crypto_skcipher_blocksize(tfm);
+ unsigned int nbytes = req->cryptlen;
+ int cbc_blocks = (nbytes + bsize - 1) / bsize - 1;
+ unsigned int offset;
+
+ skcipher_request_set_tfm(subreq, ctx->child);
+
+ if (cbc_blocks <= 0) {
+ skcipher_request_set_callback(subreq, req->base.flags,
+ req->base.complete,
+ req->base.data);
+ skcipher_request_set_crypt(subreq, req->src, req->dst, nbytes,
+ req->iv);
+ return crypto_skcipher_encrypt(subreq);
+ }
- scatterwalk_map_and_copy(d, dst, offset, nbytes, 1);
+ offset = cbc_blocks * bsize;
+ rctx->offset = offset;
- memcpy(desc->info, tmp2, bsize);
+ skcipher_request_set_callback(subreq, req->base.flags,
+ crypto_cts_encrypt_done, req);
+ skcipher_request_set_crypt(subreq, req->src, req->dst,
+ offset, req->iv);
- return err;
+ return crypto_skcipher_encrypt(subreq) ?:
+ cts_cbc_encrypt(req);
}
-static int crypto_cts_encrypt(struct blkcipher_desc *desc,
- struct scatterlist *dst, struct scatterlist *src,
- unsigned int nbytes)
+static int cts_cbc_decrypt(struct skcipher_request *req)
{
- struct crypto_cts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
- int bsize = crypto_blkcipher_blocksize(desc->tfm);
- int tot_blocks = (nbytes + bsize - 1) / bsize;
- int cbc_blocks = tot_blocks > 2 ? tot_blocks - 2 : 0;
- struct blkcipher_desc lcldesc;
- int err;
+ struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct skcipher_request *subreq = &rctx->subreq;
+ int bsize = crypto_skcipher_blocksize(tfm);
+ u8 d[bsize * 2] __attribute__ ((aligned(__alignof__(u32))));
+ struct scatterlist *sg;
+ unsigned int offset;
+ u8 *space;
+ int lastn;
+
+ offset = rctx->offset;
+ lastn = req->cryptlen - offset;
+
+ sg = scatterwalk_ffwd(rctx->sg, req->dst, offset - bsize);
+
+ /* 1. Decrypt Cn-1 (s) to create Dn */
+ scatterwalk_map_and_copy(d + bsize, sg, 0, bsize, 0);
+ space = crypto_cts_reqctx_space(req);
+ crypto_xor(d + bsize, space, bsize);
+ /* 2. Pad Cn with zeros at the end to create C of length BB */
+ memset(d, 0, bsize);
+ scatterwalk_map_and_copy(d, req->src, offset, lastn, 0);
+ /* 3. Exclusive-or Dn with C to create Xn */
+ /* 4. Select the first Ln bytes of Xn to create Pn */
+ crypto_xor(d + bsize, d, lastn);
+
+ /* 5. Append the tail (BB - Ln) bytes of Xn to Cn to create En */
+ memcpy(d + lastn, d + bsize + lastn, bsize - lastn);
+ /* 6. Decrypt En to create Pn-1 */
- lcldesc.tfm = ctx->child;
- lcldesc.info = desc->info;
- lcldesc.flags = desc->flags;
-
- if (tot_blocks == 1) {
- err = crypto_blkcipher_encrypt_iv(&lcldesc, dst, src, bsize);
- } else if (nbytes <= bsize * 2) {
- err = cts_cbc_encrypt(ctx, desc, dst, src, 0, nbytes);
- } else {
- /* do normal function for tot_blocks - 2 */
- err = crypto_blkcipher_encrypt_iv(&lcldesc, dst, src,
- cbc_blocks * bsize);
- if (err == 0) {
- /* do cts for final two blocks */
- err = cts_cbc_encrypt(ctx, desc, dst, src,
- cbc_blocks * bsize,
- nbytes - (cbc_blocks * bsize));
- }
- }
+ scatterwalk_map_and_copy(d, sg, 0, bsize + lastn, 1);
+ memzero_explicit(d, sizeof(d));
- return err;
+ skcipher_request_set_callback(subreq, req->base.flags &
+ CRYPTO_TFM_REQ_MAY_BACKLOG,
+ cts_cbc_crypt_done, req);
+
+ skcipher_request_set_crypt(subreq, sg, sg, bsize, space);
+ return crypto_skcipher_decrypt(subreq);
}
-static int cts_cbc_decrypt(struct crypto_cts_ctx *ctx,
- struct blkcipher_desc *desc,
- struct scatterlist *dst,
- struct scatterlist *src,
- unsigned int offset,
- unsigned int nbytes)
+static void crypto_cts_decrypt_done(struct crypto_async_request *areq, int err)
{
- int bsize = crypto_blkcipher_blocksize(desc->tfm);
- u8 tmp[bsize];
- struct blkcipher_desc lcldesc;
- struct scatterlist sgsrc[1], sgdst[1];
- int lastn = nbytes - bsize;
- u8 iv[bsize];
- u8 s[bsize * 2], d[bsize * 2];
- int err;
-
- if (lastn < 0)
- return -EINVAL;
+ struct skcipher_request *req = areq->data;
- sg_init_table(sgsrc, 1);
- sg_init_table(sgdst, 1);
+ if (err)
+ goto out;
- scatterwalk_map_and_copy(s, src, offset, nbytes, 0);
+ err = cts_cbc_decrypt(req);
+ if (err == -EINPROGRESS ||
+ (err == -EBUSY && req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
+ return;
- lcldesc.tfm = ctx->child;
- lcldesc.info = iv;
- lcldesc.flags = desc->flags;
+out:
+ skcipher_request_complete(req, err);
+}
- /* 1. Decrypt Cn-1 (s) to create Dn (tmp)*/
- memset(iv, 0, sizeof(iv));
- sg_set_buf(&sgsrc[0], s, bsize);
- sg_set_buf(&sgdst[0], tmp, bsize);
- err = crypto_blkcipher_decrypt_iv(&lcldesc, sgdst, sgsrc, bsize);
- if (err)
- return err;
- /* 2. Pad Cn with zeros at the end to create C of length BB */
- memset(iv, 0, sizeof(iv));
- memcpy(iv, s + bsize, lastn);
- /* 3. Exclusive-or Dn (tmp) with C (iv) to create Xn (tmp) */
- crypto_xor(tmp, iv, bsize);
- /* 4. Select the first Ln bytes of Xn (tmp) to create Pn */
- memcpy(d + bsize, tmp, lastn);
-
- /* 5. Append the tail (BB - Ln) bytes of Xn (tmp) to Cn to create En */
- memcpy(s + bsize + lastn, tmp + lastn, bsize - lastn);
- /* 6. Decrypt En to create Pn-1 */
- memzero_explicit(iv, sizeof(iv));
+static int crypto_cts_decrypt(struct skcipher_request *req)
+{
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
+ struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
+ struct skcipher_request *subreq = &rctx->subreq;
+ int bsize = crypto_skcipher_blocksize(tfm);
+ unsigned int nbytes = req->cryptlen;
+ int cbc_blocks = (nbytes + bsize - 1) / bsize - 1;
+ unsigned int offset;
+ u8 *space;
+
+ skcipher_request_set_tfm(subreq, ctx->child);
+
+ if (cbc_blocks <= 0) {
+ skcipher_request_set_callback(subreq, req->base.flags,
+ req->base.complete,
+ req->base.data);
+ skcipher_request_set_crypt(subreq, req->src, req->dst, nbytes,
+ req->iv);
+ return crypto_skcipher_decrypt(subreq);
+ }
- sg_set_buf(&sgsrc[0], s + bsize, bsize);
- sg_set_buf(&sgdst[0], d, bsize);
- err = crypto_blkcipher_decrypt_iv(&lcldesc, sgdst, sgsrc, bsize);
+ skcipher_request_set_callback(subreq, req->base.flags,
+ crypto_cts_decrypt_done, req);
- /* XOR with previous block */
- crypto_xor(d, desc->info, bsize);
+ space = crypto_cts_reqctx_space(req);
- scatterwalk_map_and_copy(d, dst, offset, nbytes, 1);
+ offset = cbc_blocks * bsize;
+ rctx->offset = offset;
- memcpy(desc->info, s, bsize);
- return err;
-}
+ if (cbc_blocks <= 1)
+ memcpy(space, req->iv, bsize);
+ else
+ scatterwalk_map_and_copy(space, req->src, offset - 2 * bsize,
+ bsize, 0);
-static int crypto_cts_decrypt(struct blkcipher_desc *desc,
- struct scatterlist *dst, struct scatterlist *src,
- unsigned int nbytes)
-{
- struct crypto_cts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
- int bsize = crypto_blkcipher_blocksize(desc->tfm);
- int tot_blocks = (nbytes + bsize - 1) / bsize;
- int cbc_blocks = tot_blocks > 2 ? tot_blocks - 2 : 0;
- struct blkcipher_desc lcldesc;
- int err;
+ skcipher_request_set_crypt(subreq, req->src, req->dst,
+ offset, req->iv);
- lcldesc.tfm = ctx->child;
- lcldesc.info = desc->info;
- lcldesc.flags = desc->flags;
-
- if (tot_blocks == 1) {
- err = crypto_blkcipher_decrypt_iv(&lcldesc, dst, src, bsize);
- } else if (nbytes <= bsize * 2) {
- err = cts_cbc_decrypt(ctx, desc, dst, src, 0, nbytes);
- } else {
- /* do normal function for tot_blocks - 2 */
- err = crypto_blkcipher_decrypt_iv(&lcldesc, dst, src,
- cbc_blocks * bsize);
- if (err == 0) {
- /* do cts for final two blocks */
- err = cts_cbc_decrypt(ctx, desc, dst, src,
- cbc_blocks * bsize,
- nbytes - (cbc_blocks * bsize));
- }
- }
- return err;
+ return crypto_skcipher_decrypt(subreq) ?:
+ cts_cbc_decrypt(req);
}
-static int crypto_cts_init_tfm(struct crypto_tfm *tfm)
+static int crypto_cts_init_tfm(struct crypto_skcipher *tfm)
{
- struct crypto_instance *inst = (void *)tfm->__crt_alg;
- struct crypto_spawn *spawn = crypto_instance_ctx(inst);
- struct crypto_cts_ctx *ctx = crypto_tfm_ctx(tfm);
- struct crypto_blkcipher *cipher;
-
- cipher = crypto_spawn_blkcipher(spawn);
+ struct skcipher_instance *inst = skcipher_alg_instance(tfm);
+ struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
+ struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
+ struct crypto_skcipher *cipher;
+ unsigned reqsize;
+ unsigned bsize;
+ unsigned align;
+
+ cipher = crypto_spawn_skcipher2(spawn);
if (IS_ERR(cipher))
return PTR_ERR(cipher);
ctx->child = cipher;
+
+ align = crypto_skcipher_alignmask(tfm);
+ bsize = crypto_skcipher_blocksize(cipher);
+ reqsize = ALIGN(sizeof(struct crypto_cts_reqctx) +
+ crypto_skcipher_reqsize(cipher),
+ crypto_tfm_ctx_alignment()) +
+ (align & ~(crypto_tfm_ctx_alignment() - 1)) + bsize;
+
+ crypto_skcipher_set_reqsize(tfm, reqsize);
+
return 0;
}
-static void crypto_cts_exit_tfm(struct crypto_tfm *tfm)
+static void crypto_cts_exit_tfm(struct crypto_skcipher *tfm)
{
- struct crypto_cts_ctx *ctx = crypto_tfm_ctx(tfm);
- crypto_free_blkcipher(ctx->child);
+ struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
+
+ crypto_free_skcipher(ctx->child);
}
-static struct crypto_instance *crypto_cts_alloc(struct rtattr **tb)
+static void crypto_cts_free(struct skcipher_instance *inst)
{
- struct crypto_instance *inst;
- struct crypto_alg *alg;
+ crypto_drop_skcipher(skcipher_instance_ctx(inst));
+ kfree(inst);
+}
+
+static int crypto_cts_create(struct crypto_template *tmpl, struct rtattr **tb)
+{
+ struct crypto_skcipher_spawn *spawn;
+ struct skcipher_instance *inst;
+ struct crypto_attr_type *algt;
+ struct skcipher_alg *alg;
+ const char *cipher_name;
int err;
- err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
+ algt = crypto_get_attr_type(tb);
+ if (IS_ERR(algt))
+ return PTR_ERR(algt);
+
+ if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
+ return -EINVAL;
+
+ cipher_name = crypto_attr_alg_name(tb[1]);
+ if (IS_ERR(cipher_name))
+ return PTR_ERR(cipher_name);
+
+ inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
+ if (!inst)
+ return -ENOMEM;
+
+ spawn = skcipher_instance_ctx(inst);
+
+ crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
+ err = crypto_grab_skcipher2(spawn, cipher_name, 0,
+ crypto_requires_sync(algt->type,
+ algt->mask));
if (err)
- return ERR_PTR(err);
+ goto err_free_inst;
- alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_BLKCIPHER,
- CRYPTO_ALG_TYPE_MASK);
- if (IS_ERR(alg))
- return ERR_CAST(alg);
+ alg = crypto_spawn_skcipher_alg(spawn);
- inst = ERR_PTR(-EINVAL);
- if (!is_power_of_2(alg->cra_blocksize))
- goto out_put_alg;
+ err = -EINVAL;
+ if (crypto_skcipher_alg_ivsize(alg) != alg->base.cra_blocksize)
+ goto err_drop_spawn;
- if (strncmp(alg->cra_name, "cbc(", 4))
- goto out_put_alg;
+ if (strncmp(alg->base.cra_name, "cbc(", 4))
+ goto err_drop_spawn;
- inst = crypto_alloc_instance("cts", alg);
- if (IS_ERR(inst))
- goto out_put_alg;
+ err = crypto_inst_setname(skcipher_crypto_instance(inst), "cts",
+ &alg->base);
+ if (err)
+ goto err_drop_spawn;
- inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
- inst->alg.cra_priority = alg->cra_priority;
- inst->alg.cra_blocksize = alg->cra_blocksize;
- inst->alg.cra_alignmask = alg->cra_alignmask;
- inst->alg.cra_type = &crypto_blkcipher_type;
+ inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
+ inst->alg.base.cra_priority = alg->base.cra_priority;
+ inst->alg.base.cra_blocksize = alg->base.cra_blocksize;
+ inst->alg.base.cra_alignmask = alg->base.cra_alignmask;
/* We access the data as u32s when xoring. */
- inst->alg.cra_alignmask |= __alignof__(u32) - 1;
+ inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
- inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
- inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize;
- inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize;
+ inst->alg.ivsize = alg->base.cra_blocksize;
+ inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg);
+ inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg);
+ inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg);
- inst->alg.cra_ctxsize = sizeof(struct crypto_cts_ctx);
+ inst->alg.base.cra_ctxsize = sizeof(struct crypto_cts_ctx);
- inst->alg.cra_init = crypto_cts_init_tfm;
- inst->alg.cra_exit = crypto_cts_exit_tfm;
+ inst->alg.init = crypto_cts_init_tfm;
+ inst->alg.exit = crypto_cts_exit_tfm;
- inst->alg.cra_blkcipher.setkey = crypto_cts_setkey;
- inst->alg.cra_blkcipher.encrypt = crypto_cts_encrypt;
- inst->alg.cra_blkcipher.decrypt = crypto_cts_decrypt;
+ inst->alg.setkey = crypto_cts_setkey;
+ inst->alg.encrypt = crypto_cts_encrypt;
+ inst->alg.decrypt = crypto_cts_decrypt;
-out_put_alg:
- crypto_mod_put(alg);
- return inst;
-}
+ inst->free = crypto_cts_free;
-static void crypto_cts_free(struct crypto_instance *inst)
-{
- crypto_drop_spawn(crypto_instance_ctx(inst));
+ err = skcipher_register_instance(tmpl, inst);
+ if (err)
+ goto err_drop_spawn;
+
+out:
+ return err;
+
+err_drop_spawn:
+ crypto_drop_skcipher(spawn);
+err_free_inst:
kfree(inst);
+ goto out;
}
static struct crypto_template crypto_cts_tmpl = {
.name = "cts",
- .alloc = crypto_cts_alloc,
- .free = crypto_cts_free,
+ .create = crypto_cts_create,
.module = THIS_MODULE,
};
git.samba.org / sfrench / cifs-2.6.git / blobdiff