]> git.ipfire.org Git - thirdparty/linux.git/commitdiff
crypto: hctr2 - Convert to use POLYVAL library
authorEric Biggers <ebiggers@kernel.org>
Sun, 9 Nov 2025 23:47:21 +0000 (15:47 -0800)
committerEric Biggers <ebiggers@kernel.org>
Tue, 11 Nov 2025 19:03:38 +0000 (11:03 -0800)
The "hash function" in hctr2 is fixed at POLYVAL; it can never vary.
Just use the POLYVAL library, which is much easier to use than the
crypto_shash API.  It's faster, uses fixed-size structs, and never fails
(all the functions return void).

Note that this eliminates the only known user of the polyval support in
crypto_shash.  A later commit will remove support for polyval from
crypto_shash, given that the library API is sufficient.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251109234726.638437-7-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
crypto/Kconfig
crypto/hctr2.c
crypto/testmgr.c

index 57b85e903cf0b2247f2c03cb4da6460ae63f8388..805172f75bf1c05dc4491e0795ac45a24bd0e2a0 100644 (file)
@@ -696,7 +696,7 @@ config CRYPTO_ECB
 config CRYPTO_HCTR2
        tristate "HCTR2"
        select CRYPTO_XCTR
-       select CRYPTO_POLYVAL
+       select CRYPTO_LIB_POLYVAL
        select CRYPTO_MANAGER
        help
          HCTR2 length-preserving encryption mode
index c8932777bba8d61d36842efd529e7ac6444db0d1..f4cd6c29b4d397d0dd13b5b818e9b37dafeb03aa 100644 (file)
@@ -17,7 +17,6 @@
  */
 
 #include <crypto/internal/cipher.h>
-#include <crypto/internal/hash.h>
 #include <crypto/internal/skcipher.h>
 #include <crypto/polyval.h>
 #include <crypto/scatterwalk.h>
 struct hctr2_instance_ctx {
        struct crypto_cipher_spawn blockcipher_spawn;
        struct crypto_skcipher_spawn xctr_spawn;
-       struct crypto_shash_spawn polyval_spawn;
 };
 
 struct hctr2_tfm_ctx {
        struct crypto_cipher *blockcipher;
        struct crypto_skcipher *xctr;
-       struct crypto_shash *polyval;
+       struct polyval_key poly_key;
+       struct polyval_elem hashed_tweaklens[2];
        u8 L[BLOCKCIPHER_BLOCK_SIZE];
-       int hashed_tweak_offset;
-       /*
-        * This struct is allocated with extra space for two exported hash
-        * states.  Since the hash state size is not known at compile-time, we
-        * can't add these to the struct directly.
-        *
-        * hashed_tweaklen_divisible;
-        * hashed_tweaklen_remainder;
-        */
 };
 
 struct hctr2_request_ctx {
@@ -63,39 +53,17 @@ struct hctr2_request_ctx {
        struct scatterlist *bulk_part_src;
        struct scatterlist sg_src[2];
        struct scatterlist sg_dst[2];
+       struct polyval_elem hashed_tweak;
        /*
-        * Sub-request sizes are unknown at compile-time, so they need to go
-        * after the members with known sizes.
+        * skcipher sub-request size is unknown at compile-time, so it needs to
+        * go after the members with known sizes.
         */
        union {
-               struct shash_desc hash_desc;
+               struct polyval_ctx poly_ctx;
                struct skcipher_request xctr_req;
        } u;
-       /*
-        * This struct is allocated with extra space for one exported hash
-        * state.  Since the hash state size is not known at compile-time, we
-        * can't add it to the struct directly.
-        *
-        * hashed_tweak;
-        */
 };
 
-static inline u8 *hctr2_hashed_tweaklen(const struct hctr2_tfm_ctx *tctx,
-                                       bool has_remainder)
-{
-       u8 *p = (u8 *)tctx + sizeof(*tctx);
-
-       if (has_remainder) /* For messages not a multiple of block length */
-               p += crypto_shash_statesize(tctx->polyval);
-       return p;
-}
-
-static inline u8 *hctr2_hashed_tweak(const struct hctr2_tfm_ctx *tctx,
-                                    struct hctr2_request_ctx *rctx)
-{
-       return (u8 *)rctx + tctx->hashed_tweak_offset;
-}
-
 /*
  * The input data for each HCTR2 hash step begins with a 16-byte block that
  * contains the tweak length and a flag that indicates whether the input is evenly
@@ -106,24 +74,23 @@ static inline u8 *hctr2_hashed_tweak(const struct hctr2_tfm_ctx *tctx,
  *
  * These precomputed hashes are stored in hctr2_tfm_ctx.
  */
-static int hctr2_hash_tweaklen(struct hctr2_tfm_ctx *tctx, bool has_remainder)
+static void hctr2_hash_tweaklens(struct hctr2_tfm_ctx *tctx)
 {
-       SHASH_DESC_ON_STACK(shash, tfm->polyval);
-       __le64 tweak_length_block[2];
-       int err;
-
-       shash->tfm = tctx->polyval;
-       memset(tweak_length_block, 0, sizeof(tweak_length_block));
-
-       tweak_length_block[0] = cpu_to_le64(TWEAK_SIZE * 8 * 2 + 2 + has_remainder);
-       err = crypto_shash_init(shash);
-       if (err)
-               return err;
-       err = crypto_shash_update(shash, (u8 *)tweak_length_block,
-                                 POLYVAL_BLOCK_SIZE);
-       if (err)
-               return err;
-       return crypto_shash_export(shash, hctr2_hashed_tweaklen(tctx, has_remainder));
+       struct polyval_ctx ctx;
+
+       for (int has_remainder = 0; has_remainder < 2; has_remainder++) {
+               const __le64 tweak_length_block[2] = {
+                       cpu_to_le64(TWEAK_SIZE * 8 * 2 + 2 + has_remainder),
+               };
+
+               polyval_init(&ctx, &tctx->poly_key);
+               polyval_update(&ctx, (const u8 *)&tweak_length_block,
+                              sizeof(tweak_length_block));
+               static_assert(sizeof(tweak_length_block) == POLYVAL_BLOCK_SIZE);
+               polyval_export_blkaligned(
+                       &ctx, &tctx->hashed_tweaklens[has_remainder]);
+       }
+       memzero_explicit(&ctx, sizeof(ctx));
 }
 
 static int hctr2_setkey(struct crypto_skcipher *tfm, const u8 *key,
@@ -156,51 +123,42 @@ static int hctr2_setkey(struct crypto_skcipher *tfm, const u8 *key,
        tctx->L[0] = 0x01;
        crypto_cipher_encrypt_one(tctx->blockcipher, tctx->L, tctx->L);
 
-       crypto_shash_clear_flags(tctx->polyval, CRYPTO_TFM_REQ_MASK);
-       crypto_shash_set_flags(tctx->polyval, crypto_skcipher_get_flags(tfm) &
-                              CRYPTO_TFM_REQ_MASK);
-       err = crypto_shash_setkey(tctx->polyval, hbar, BLOCKCIPHER_BLOCK_SIZE);
-       if (err)
-               return err;
+       static_assert(sizeof(hbar) == POLYVAL_BLOCK_SIZE);
+       polyval_preparekey(&tctx->poly_key, hbar);
        memzero_explicit(hbar, sizeof(hbar));
 
-       return hctr2_hash_tweaklen(tctx, true) ?: hctr2_hash_tweaklen(tctx, false);
+       hctr2_hash_tweaklens(tctx);
+       return 0;
 }
 
-static int hctr2_hash_tweak(struct skcipher_request *req)
+static void hctr2_hash_tweak(struct skcipher_request *req)
 {
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        const struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
        struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
-       struct shash_desc *hash_desc = &rctx->u.hash_desc;
-       int err;
+       struct polyval_ctx *poly_ctx = &rctx->u.poly_ctx;
        bool has_remainder = req->cryptlen % POLYVAL_BLOCK_SIZE;
 
-       hash_desc->tfm = tctx->polyval;
-       err = crypto_shash_import(hash_desc, hctr2_hashed_tweaklen(tctx, has_remainder));
-       if (err)
-               return err;
-       err = crypto_shash_update(hash_desc, req->iv, TWEAK_SIZE);
-       if (err)
-               return err;
+       polyval_import_blkaligned(poly_ctx, &tctx->poly_key,
+                                 &tctx->hashed_tweaklens[has_remainder]);
+       polyval_update(poly_ctx, req->iv, TWEAK_SIZE);
 
        // Store the hashed tweak, since we need it when computing both
        // H(T || N) and H(T || V).
-       return crypto_shash_export(hash_desc, hctr2_hashed_tweak(tctx, rctx));
+       static_assert(TWEAK_SIZE % POLYVAL_BLOCK_SIZE == 0);
+       polyval_export_blkaligned(poly_ctx, &rctx->hashed_tweak);
 }
 
-static int hctr2_hash_message(struct skcipher_request *req,
-                             struct scatterlist *sgl,
-                             u8 digest[POLYVAL_DIGEST_SIZE])
+static void hctr2_hash_message(struct skcipher_request *req,
+                              struct scatterlist *sgl,
+                              u8 digest[POLYVAL_DIGEST_SIZE])
 {
-       static const u8 padding[BLOCKCIPHER_BLOCK_SIZE] = { 0x1 };
+       static const u8 padding = 0x1;
        struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
-       struct shash_desc *hash_desc = &rctx->u.hash_desc;
+       struct polyval_ctx *poly_ctx = &rctx->u.poly_ctx;
        const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
        struct sg_mapping_iter miter;
-       unsigned int remainder = bulk_len % BLOCKCIPHER_BLOCK_SIZE;
        int i;
-       int err = 0;
        int n = 0;
 
        sg_miter_start(&miter, sgl, sg_nents(sgl),
@@ -208,22 +166,13 @@ static int hctr2_hash_message(struct skcipher_request *req,
        for (i = 0; i < bulk_len; i += n) {
                sg_miter_next(&miter);
                n = min_t(unsigned int, miter.length, bulk_len - i);
-               err = crypto_shash_update(hash_desc, miter.addr, n);
-               if (err)
-                       break;
+               polyval_update(poly_ctx, miter.addr, n);
        }
        sg_miter_stop(&miter);
 
-       if (err)
-               return err;
-
-       if (remainder) {
-               err = crypto_shash_update(hash_desc, padding,
-                                         BLOCKCIPHER_BLOCK_SIZE - remainder);
-               if (err)
-                       return err;
-       }
-       return crypto_shash_final(hash_desc, digest);
+       if (req->cryptlen % BLOCKCIPHER_BLOCK_SIZE)
+               polyval_update(poly_ctx, &padding, 1);
+       polyval_final(poly_ctx, digest);
 }
 
 static int hctr2_finish(struct skcipher_request *req)
@@ -231,19 +180,14 @@ static int hctr2_finish(struct skcipher_request *req)
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        const struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
        struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
+       struct polyval_ctx *poly_ctx = &rctx->u.poly_ctx;
        u8 digest[POLYVAL_DIGEST_SIZE];
-       struct shash_desc *hash_desc = &rctx->u.hash_desc;
-       int err;
 
        // U = UU ^ H(T || V)
        // or M = MM ^ H(T || N)
-       hash_desc->tfm = tctx->polyval;
-       err = crypto_shash_import(hash_desc, hctr2_hashed_tweak(tctx, rctx));
-       if (err)
-               return err;
-       err = hctr2_hash_message(req, rctx->bulk_part_dst, digest);
-       if (err)
-               return err;
+       polyval_import_blkaligned(poly_ctx, &tctx->poly_key,
+                                 &rctx->hashed_tweak);
+       hctr2_hash_message(req, rctx->bulk_part_dst, digest);
        crypto_xor(rctx->first_block, digest, BLOCKCIPHER_BLOCK_SIZE);
 
        // Copy U (or M) into dst scatterlist
@@ -269,7 +213,6 @@ static int hctr2_crypt(struct skcipher_request *req, bool enc)
        struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
        u8 digest[POLYVAL_DIGEST_SIZE];
        int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
-       int err;
 
        // Requests must be at least one block
        if (req->cryptlen < BLOCKCIPHER_BLOCK_SIZE)
@@ -287,12 +230,8 @@ static int hctr2_crypt(struct skcipher_request *req, bool enc)
 
        // MM = M ^ H(T || N)
        // or UU = U ^ H(T || V)
-       err = hctr2_hash_tweak(req);
-       if (err)
-               return err;
-       err = hctr2_hash_message(req, rctx->bulk_part_src, digest);
-       if (err)
-               return err;
+       hctr2_hash_tweak(req);
+       hctr2_hash_message(req, rctx->bulk_part_src, digest);
        crypto_xor(digest, rctx->first_block, BLOCKCIPHER_BLOCK_SIZE);
 
        // UU = E(MM)
@@ -338,8 +277,6 @@ static int hctr2_init_tfm(struct crypto_skcipher *tfm)
        struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
        struct crypto_skcipher *xctr;
        struct crypto_cipher *blockcipher;
-       struct crypto_shash *polyval;
-       unsigned int subreq_size;
        int err;
 
        xctr = crypto_spawn_skcipher(&ictx->xctr_spawn);
@@ -352,31 +289,17 @@ static int hctr2_init_tfm(struct crypto_skcipher *tfm)
                goto err_free_xctr;
        }
 
-       polyval = crypto_spawn_shash(&ictx->polyval_spawn);
-       if (IS_ERR(polyval)) {
-               err = PTR_ERR(polyval);
-               goto err_free_blockcipher;
-       }
-
        tctx->xctr = xctr;
        tctx->blockcipher = blockcipher;
-       tctx->polyval = polyval;
 
        BUILD_BUG_ON(offsetofend(struct hctr2_request_ctx, u) !=
                                 sizeof(struct hctr2_request_ctx));
-       subreq_size = max(sizeof_field(struct hctr2_request_ctx, u.hash_desc) +
-                         crypto_shash_descsize(polyval),
-                         sizeof_field(struct hctr2_request_ctx, u.xctr_req) +
-                         crypto_skcipher_reqsize(xctr));
-
-       tctx->hashed_tweak_offset = offsetof(struct hctr2_request_ctx, u) +
-                                   subreq_size;
-       crypto_skcipher_set_reqsize(tfm, tctx->hashed_tweak_offset +
-                                   crypto_shash_statesize(polyval));
+       crypto_skcipher_set_reqsize(
+               tfm, max(sizeof(struct hctr2_request_ctx),
+                        offsetofend(struct hctr2_request_ctx, u.xctr_req) +
+                                crypto_skcipher_reqsize(xctr)));
        return 0;
 
-err_free_blockcipher:
-       crypto_free_cipher(blockcipher);
 err_free_xctr:
        crypto_free_skcipher(xctr);
        return err;
@@ -388,7 +311,6 @@ static void hctr2_exit_tfm(struct crypto_skcipher *tfm)
 
        crypto_free_cipher(tctx->blockcipher);
        crypto_free_skcipher(tctx->xctr);
-       crypto_free_shash(tctx->polyval);
 }
 
 static void hctr2_free_instance(struct skcipher_instance *inst)
@@ -397,21 +319,17 @@ static void hctr2_free_instance(struct skcipher_instance *inst)
 
        crypto_drop_cipher(&ictx->blockcipher_spawn);
        crypto_drop_skcipher(&ictx->xctr_spawn);
-       crypto_drop_shash(&ictx->polyval_spawn);
        kfree(inst);
 }
 
-static int hctr2_create_common(struct crypto_template *tmpl,
-                              struct rtattr **tb,
-                              const char *xctr_name,
-                              const char *polyval_name)
+static int hctr2_create_common(struct crypto_template *tmpl, struct rtattr **tb,
+                              const char *xctr_name)
 {
        struct skcipher_alg_common *xctr_alg;
        u32 mask;
        struct skcipher_instance *inst;
        struct hctr2_instance_ctx *ictx;
        struct crypto_alg *blockcipher_alg;
-       struct shash_alg *polyval_alg;
        char blockcipher_name[CRYPTO_MAX_ALG_NAME];
        int len;
        int err;
@@ -457,19 +375,6 @@ static int hctr2_create_common(struct crypto_template *tmpl,
        if (blockcipher_alg->cra_blocksize != BLOCKCIPHER_BLOCK_SIZE)
                goto err_free_inst;
 
-       /* Polyval ε-∆U hash function */
-       err = crypto_grab_shash(&ictx->polyval_spawn,
-                               skcipher_crypto_instance(inst),
-                               polyval_name, 0, mask);
-       if (err)
-               goto err_free_inst;
-       polyval_alg = crypto_spawn_shash_alg(&ictx->polyval_spawn);
-
-       /* Ensure Polyval is being used */
-       err = -EINVAL;
-       if (strcmp(polyval_alg->base.cra_name, "polyval") != 0)
-               goto err_free_inst;
-
        /* Instance fields */
 
        err = -ENAMETOOLONG;
@@ -477,22 +382,16 @@ static int hctr2_create_common(struct crypto_template *tmpl,
                     blockcipher_alg->cra_name) >= CRYPTO_MAX_ALG_NAME)
                goto err_free_inst;
        if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
-                    "hctr2_base(%s,%s)",
-                    xctr_alg->base.cra_driver_name,
-                    polyval_alg->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
+                    "hctr2_base(%s,polyval-lib)",
+                    xctr_alg->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
                goto err_free_inst;
 
        inst->alg.base.cra_blocksize = BLOCKCIPHER_BLOCK_SIZE;
-       inst->alg.base.cra_ctxsize = sizeof(struct hctr2_tfm_ctx) +
-                                    polyval_alg->statesize * 2;
+       inst->alg.base.cra_ctxsize = sizeof(struct hctr2_tfm_ctx);
        inst->alg.base.cra_alignmask = xctr_alg->base.cra_alignmask;
-       /*
-        * The hash function is called twice, so it is weighted higher than the
-        * xctr and blockcipher.
-        */
        inst->alg.base.cra_priority = (2 * xctr_alg->base.cra_priority +
-                                      4 * polyval_alg->base.cra_priority +
-                                      blockcipher_alg->cra_priority) / 7;
+                                      blockcipher_alg->cra_priority) /
+                                     3;
 
        inst->alg.setkey = hctr2_setkey;
        inst->alg.encrypt = hctr2_encrypt;
@@ -525,8 +424,11 @@ static int hctr2_create_base(struct crypto_template *tmpl, struct rtattr **tb)
        polyval_name = crypto_attr_alg_name(tb[2]);
        if (IS_ERR(polyval_name))
                return PTR_ERR(polyval_name);
+       if (strcmp(polyval_name, "polyval") != 0 &&
+           strcmp(polyval_name, "polyval-lib") != 0)
+               return -ENOENT;
 
-       return hctr2_create_common(tmpl, tb, xctr_name, polyval_name);
+       return hctr2_create_common(tmpl, tb, xctr_name);
 }
 
 static int hctr2_create(struct crypto_template *tmpl, struct rtattr **tb)
@@ -542,7 +444,7 @@ static int hctr2_create(struct crypto_template *tmpl, struct rtattr **tb)
                    blockcipher_name) >= CRYPTO_MAX_ALG_NAME)
                return -ENAMETOOLONG;
 
-       return hctr2_create_common(tmpl, tb, xctr_name, "polyval");
+       return hctr2_create_common(tmpl, tb, xctr_name);
 }
 
 static struct crypto_template hctr2_tmpls[] = {
index 90d06c3ec96797b5a4b8d92b86706f47f21cec90..499e979a56dc4680652a32b14cd9bf7e650c3c11 100644 (file)
@@ -5059,8 +5059,7 @@ static const struct alg_test_desc alg_test_descs[] = {
                }
        }, {
                .alg = "hctr2(aes)",
-               .generic_driver =
-                   "hctr2_base(xctr(aes-generic),polyval-generic)",
+               .generic_driver = "hctr2_base(xctr(aes-generic),polyval-lib)",
                .test = alg_test_skcipher,
                .suite = {
                        .cipher = __VECS(aes_hctr2_tv_template)