#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>
-#define LRW_BUFFER_SIZE 128u
-
#define LRW_BLOCK_SIZE 16
struct priv {
};
struct rctx {
- be128 buf[LRW_BUFFER_SIZE / sizeof(be128)];
-
be128 t;
-
- be128 *ext;
-
- struct scatterlist srcbuf[2];
- struct scatterlist dstbuf[2];
- struct scatterlist *src;
- struct scatterlist *dst;
-
- unsigned int left;
-
struct skcipher_request subreq;
};
return 0;
}
-static inline void inc(be128 *iv)
-{
- be64_add_cpu(&iv->b, 1);
- if (!iv->b)
- be64_add_cpu(&iv->a, 1);
-}
-
-/* this returns the number of consequative 1 bits starting
- * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
-static inline int get_index128(be128 *block)
+/*
+ * Returns the number of trailing '1' bits in the words of the counter, which is
+ * represented by 4 32-bit words, arranged from least to most significant.
+ * At the same time, increments the counter by one.
+ *
+ * For example:
+ *
+ * u32 counter[4] = { 0xFFFFFFFF, 0x1, 0x0, 0x0 };
+ * int i = next_index(&counter);
+ * // i == 33, counter == { 0x0, 0x2, 0x0, 0x0 }
+ */
+static int next_index(u32 *counter)
{
- int x;
- __be32 *p = (__be32 *) block;
+ int i, res = 0;
- for (p += 3, x = 0; x < 128; p--, x += 32) {
- u32 val = be32_to_cpup(p);
+ for (i = 0; i < 4; i++) {
+ if (counter[i] + 1 != 0)
+ return res + ffz(counter[i]++);
- if (!~val)
- continue;
-
- return x + ffz(val);
+ counter[i] = 0;
+ res += 32;
}
- return x;
+ /*
+ * If we get here, then x == 128 and we are incrementing the counter
+ * from all ones to all zeros. This means we must return index 127, i.e.
+ * the one corresponding to key2*{ 1,...,1 }.
+ */
+ return 127;
}
-static int post_crypt(struct skcipher_request *req)
+/*
+ * We compute the tweak masks twice (both before and after the ECB encryption or
+ * decryption) to avoid having to allocate a temporary buffer and/or make
+ * mutliple calls to the 'ecb(..)' instance, which usually would be slower than
+ * just doing the next_index() calls again.
+ */
+static int xor_tweak(struct skcipher_request *req, bool second_pass)
{
- struct rctx *rctx = skcipher_request_ctx(req);
- be128 *buf = rctx->ext ?: rctx->buf;
- struct skcipher_request *subreq;
const int bs = LRW_BLOCK_SIZE;
- struct skcipher_walk w;
- struct scatterlist *sg;
- unsigned offset;
- int err;
-
- subreq = &rctx->subreq;
- err = skcipher_walk_virt(&w, subreq, false);
-
- while (w.nbytes) {
- unsigned int avail = w.nbytes;
- be128 *wdst;
-
- wdst = w.dst.virt.addr;
-
- do {
- be128_xor(wdst, buf++, wdst);
- wdst++;
- } while ((avail -= bs) >= bs);
-
- err = skcipher_walk_done(&w, avail);
- }
-
- rctx->left -= subreq->cryptlen;
-
- if (err || !rctx->left)
- goto out;
-
- rctx->dst = rctx->dstbuf;
-
- scatterwalk_done(&w.out, 0, 1);
- sg = w.out.sg;
- offset = w.out.offset;
-
- if (rctx->dst != sg) {
- rctx->dst[0] = *sg;
- sg_unmark_end(rctx->dst);
- scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 2);
- }
- rctx->dst[0].length -= offset - sg->offset;
- rctx->dst[0].offset = offset;
-
-out:
- return err;
-}
-
-static int pre_crypt(struct skcipher_request *req)
-{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
- struct rctx *rctx = skcipher_request_ctx(req);
struct priv *ctx = crypto_skcipher_ctx(tfm);
- be128 *buf = rctx->ext ?: rctx->buf;
- struct skcipher_request *subreq;
- const int bs = LRW_BLOCK_SIZE;
+ struct rctx *rctx = skcipher_request_ctx(req);
+ be128 t = rctx->t;
struct skcipher_walk w;
- struct scatterlist *sg;
- unsigned cryptlen;
- unsigned offset;
- be128 *iv;
- bool more;
+ __be32 *iv;
+ u32 counter[4];
int err;
- subreq = &rctx->subreq;
- skcipher_request_set_tfm(subreq, tfm);
-
- cryptlen = subreq->cryptlen;
- more = rctx->left > cryptlen;
- if (!more)
- cryptlen = rctx->left;
+ if (second_pass) {
+ req = &rctx->subreq;
+ /* set to our TFM to enforce correct alignment: */
+ skcipher_request_set_tfm(req, tfm);
+ }
- skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
- cryptlen, req->iv);
+ err = skcipher_walk_virt(&w, req, false);
+ iv = (__be32 *)w.iv;
- err = skcipher_walk_virt(&w, subreq, false);
- iv = w.iv;
+ counter[0] = be32_to_cpu(iv[3]);
+ counter[1] = be32_to_cpu(iv[2]);
+ counter[2] = be32_to_cpu(iv[1]);
+ counter[3] = be32_to_cpu(iv[0]);
while (w.nbytes) {
unsigned int avail = w.nbytes;
wdst = w.dst.virt.addr;
do {
- *buf++ = rctx->t;
- be128_xor(wdst++, &rctx->t, wsrc++);
+ be128_xor(wdst++, &t, wsrc++);
/* T <- I*Key2, using the optimization
* discussed in the specification */
- be128_xor(&rctx->t, &rctx->t,
- &ctx->mulinc[get_index128(iv)]);
- inc(iv);
+ be128_xor(&t, &t, &ctx->mulinc[next_index(counter)]);
} while ((avail -= bs) >= bs);
- err = skcipher_walk_done(&w, avail);
- }
-
- skcipher_request_set_tfm(subreq, ctx->child);
- skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
- cryptlen, NULL);
-
- if (err || !more)
- goto out;
-
- rctx->src = rctx->srcbuf;
-
- scatterwalk_done(&w.in, 0, 1);
- sg = w.in.sg;
- offset = w.in.offset;
+ if (second_pass && w.nbytes == w.total) {
+ iv[0] = cpu_to_be32(counter[3]);
+ iv[1] = cpu_to_be32(counter[2]);
+ iv[2] = cpu_to_be32(counter[1]);
+ iv[3] = cpu_to_be32(counter[0]);
+ }
- if (rctx->src != sg) {
- rctx->src[0] = *sg;
- sg_unmark_end(rctx->src);
- scatterwalk_crypto_chain(rctx->src, sg_next(sg), 2);
+ err = skcipher_walk_done(&w, avail);
}
- rctx->src[0].length -= offset - sg->offset;
- rctx->src[0].offset = offset;
-out:
return err;
}
-static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
+static int xor_tweak_pre(struct skcipher_request *req)
{
- struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
- struct rctx *rctx = skcipher_request_ctx(req);
- struct skcipher_request *subreq;
- gfp_t gfp;
-
- subreq = &rctx->subreq;
- skcipher_request_set_callback(subreq, req->base.flags, done, req);
-
- gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
- GFP_ATOMIC;
- rctx->ext = NULL;
-
- subreq->cryptlen = LRW_BUFFER_SIZE;
- if (req->cryptlen > LRW_BUFFER_SIZE) {
- unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
-
- rctx->ext = kmalloc(n, gfp);
- if (rctx->ext)
- subreq->cryptlen = n;
- }
-
- rctx->src = req->src;
- rctx->dst = req->dst;
- rctx->left = req->cryptlen;
-
- /* calculate first value of T */
- memcpy(&rctx->t, req->iv, sizeof(rctx->t));
-
- /* T <- I*Key2 */
- gf128mul_64k_bbe(&rctx->t, ctx->table);
-
- return 0;
+ return xor_tweak(req, false);
}
-static void exit_crypt(struct skcipher_request *req)
+static int xor_tweak_post(struct skcipher_request *req)
{
- struct rctx *rctx = skcipher_request_ctx(req);
-
- rctx->left = 0;
-
- if (rctx->ext)
- kzfree(rctx->ext);
+ return xor_tweak(req, true);
}
-static int do_encrypt(struct skcipher_request *req, int err)
-{
- struct rctx *rctx = skcipher_request_ctx(req);
- struct skcipher_request *subreq;
-
- subreq = &rctx->subreq;
-
- while (!err && rctx->left) {
- err = pre_crypt(req) ?:
- crypto_skcipher_encrypt(subreq) ?:
- post_crypt(req);
-
- if (err == -EINPROGRESS || err == -EBUSY)
- return err;
- }
-
- exit_crypt(req);
- return err;
-}
-
-static void encrypt_done(struct crypto_async_request *areq, int err)
+static void crypt_done(struct crypto_async_request *areq, int err)
{
struct skcipher_request *req = areq->data;
- struct skcipher_request *subreq;
- struct rctx *rctx;
- rctx = skcipher_request_ctx(req);
+ if (!err)
+ err = xor_tweak_post(req);
- if (err == -EINPROGRESS) {
- if (rctx->left != req->cryptlen)
- return;
- goto out;
- }
-
- subreq = &rctx->subreq;
- subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
-
- err = do_encrypt(req, err ?: post_crypt(req));
- if (rctx->left)
- return;
-
-out:
skcipher_request_complete(req, err);
}
-static int encrypt(struct skcipher_request *req)
-{
- return do_encrypt(req, init_crypt(req, encrypt_done));
-}
-
-static int do_decrypt(struct skcipher_request *req, int err)
+static void init_crypt(struct skcipher_request *req)
{
+ struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
struct rctx *rctx = skcipher_request_ctx(req);
- struct skcipher_request *subreq;
-
- subreq = &rctx->subreq;
+ struct skcipher_request *subreq = &rctx->subreq;
- while (!err && rctx->left) {
- err = pre_crypt(req) ?:
- crypto_skcipher_decrypt(subreq) ?:
- post_crypt(req);
+ skcipher_request_set_tfm(subreq, ctx->child);
+ skcipher_request_set_callback(subreq, req->base.flags, crypt_done, req);
+ /* pass req->iv as IV (will be used by xor_tweak, ECB will ignore it) */
+ skcipher_request_set_crypt(subreq, req->dst, req->dst,
+ req->cryptlen, req->iv);
- if (err == -EINPROGRESS || err == -EBUSY)
- return err;
- }
+ /* calculate first value of T */
+ memcpy(&rctx->t, req->iv, sizeof(rctx->t));
- exit_crypt(req);
- return err;
+ /* T <- I*Key2 */
+ gf128mul_64k_bbe(&rctx->t, ctx->table);
}
-static void decrypt_done(struct crypto_async_request *areq, int err)
+static int encrypt(struct skcipher_request *req)
{
- struct skcipher_request *req = areq->data;
- struct skcipher_request *subreq;
- struct rctx *rctx;
-
- rctx = skcipher_request_ctx(req);
-
- if (err == -EINPROGRESS) {
- if (rctx->left != req->cryptlen)
- return;
- goto out;
- }
-
- subreq = &rctx->subreq;
- subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
-
- err = do_decrypt(req, err ?: post_crypt(req));
- if (rctx->left)
- return;
+ struct rctx *rctx = skcipher_request_ctx(req);
+ struct skcipher_request *subreq = &rctx->subreq;
-out:
- skcipher_request_complete(req, err);
+ init_crypt(req);
+ return xor_tweak_pre(req) ?:
+ crypto_skcipher_encrypt(subreq) ?:
+ xor_tweak_post(req);
}
static int decrypt(struct skcipher_request *req)
{
- return do_decrypt(req, init_crypt(req, decrypt_done));
+ struct rctx *rctx = skcipher_request_ctx(req);
+ struct skcipher_request *subreq = &rctx->subreq;
+
+ init_crypt(req);
+ return xor_tweak_pre(req) ?:
+ crypto_skcipher_decrypt(subreq) ?:
+ xor_tweak_post(req);
}
static int init_tfm(struct crypto_skcipher *tfm)
inst->alg.base.cra_priority = alg->base.cra_priority;
inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
- (__alignof__(u64) - 1);
+ (__alignof__(__be32) - 1);
inst->alg.ivsize = LRW_BLOCK_SIZE;
inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
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