Add shake256 support to the SHA-3 crypto_sig module so that ML-DSA can use
it.

Signed-off-by: David Howells <[email protected]>
cc: Stephan Mueller <[email protected]>
cc: Eric Biggers <[email protected]>
cc: Jason A. Donenfeld <[email protected]>
cc: Ard Biesheuvel <[email protected]>
cc: Herbert Xu <[email protected]>
cc: [email protected]
---
 crypto/sha3.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/crypto/sha3.c b/crypto/sha3.c
index 8f364979ec89..be1d18baee8d 100644
--- a/crypto/sha3.c
+++ b/crypto/sha3.c
@@ -9,6 +9,7 @@
 #include <linux/module.h>
 
 #define SHA3_CTX(desc) ((struct sha3_ctx *)shash_desc_ctx(desc))
+#define SHAKE_CTX(desc) ((struct shake_ctx *)shash_desc_ctx(desc))
 
 static int crypto_sha3_224_init(struct shash_desc *desc)
 {
@@ -87,6 +88,36 @@ static int crypto_sha3_import_core(struct shash_desc *desc, 
const void *in)
        return 0;
 }
 
+static int crypto_shake256_init(struct shash_desc *desc)
+{
+       shake256_init(SHAKE_CTX(desc));
+       return 0;
+}
+
+static int crypto_shake_update(struct shash_desc *desc, const u8 *data,
+                             unsigned int len)
+{
+       shake_update(SHAKE_CTX(desc), data, len);
+       return 0;
+}
+
+static int crypto_shake_final(struct shash_desc *desc, u8 *out)
+{
+       const struct shash_alg *alg = crypto_shash_alg(desc->tfm);
+
+       shake_squeeze(SHAKE_CTX(desc), out, alg->digestsize);
+       return 0;
+}
+
+static int crypto_shake256_digest(struct shash_desc *desc,
+                                 const u8 *data, unsigned int len, u8 *out)
+{
+       const struct shash_alg *alg = crypto_shash_alg(desc->tfm);
+
+       shake256(data, len, out, alg->digestsize);
+       return 0;
+}
+
 static struct shash_alg algs[] = { {
        .digestsize             = SHA3_224_DIGEST_SIZE,
        .init                   = crypto_sha3_224_init,
@@ -139,6 +170,17 @@ static struct shash_alg algs[] = { {
        .base.cra_driver_name   = "sha3-512-lib",
        .base.cra_blocksize     = SHA3_512_BLOCK_SIZE,
        .base.cra_module        = THIS_MODULE,
+}, {
+       .digestsize             = SHAKE256_DEFAULT_SIZE,
+       .init                   = crypto_shake256_init,
+       .update                 = crypto_shake_update,
+       .final                  = crypto_shake_final,
+       .digest                 = crypto_shake256_digest,
+       .descsize               = sizeof(struct shake_ctx),
+       .base.cra_name          = "shake256",
+       .base.cra_driver_name   = "shake256-lib",
+       .base.cra_blocksize     = SHAKE256_BLOCK_SIZE,
+       .base.cra_module        = THIS_MODULE,
 } };
 
 static int __init crypto_sha3_mod_init(void)


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