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Date:   Thu, 11 May 2023 11:33:56 +0800
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Ross Philipson <ross.philipson@oracle.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-integrity@vger.kernel.org, linux-doc@vger.kernel.org,
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Subject: Re: [PATCH v6 06/14] x86: Add early SHA support for Secure Launch
 early measurements
Message-ID: <ZFxiJF373HCwZLKE@gondor.apana.org.au>
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Ross Philipson <ross.philipson@oracle.com> wrote:
>
> +static void __sha_transform(u32 *digest, const char *data)
> +{
> +       u32 ws[SHA1_WORKSPACE_WORDS];
> +
> +       sha1_transform(digest, data, ws);
> +
> +       memzero_explicit(ws, sizeof(ws));
> +}
> +
> +void early_sha1_init(struct sha1_state *sctx)
> +{
> +       sha1_init(sctx->state);
> +       sctx->count = 0;
> +}
> +
> +void early_sha1_update(struct sha1_state *sctx,
> +                      const u8 *data,
> +                      unsigned int len)
> +{
> +       unsigned int partial = sctx->count % SHA1_BLOCK_SIZE;
> +
> +       sctx->count += len;
> +
> +       if (likely((partial + len) >= SHA1_BLOCK_SIZE)) {
> +               int blocks;
> +
> +               if (partial) {
> +                       int p = SHA1_BLOCK_SIZE - partial;
> +
> +                       memcpy(sctx->buffer + partial, data, p);
> +                       data += p;
> +                       len -= p;
> +
> +                       __sha_transform(sctx->state, sctx->buffer);
> +               }
> +
> +               blocks = len / SHA1_BLOCK_SIZE;
> +               len %= SHA1_BLOCK_SIZE;
> +
> +               if (blocks) {
> +                       while (blocks--) {
> +                               __sha_transform(sctx->state, data);
> +                               data += SHA1_BLOCK_SIZE;
> +                       }
> +               }
> +               partial = 0;
> +       }
> +
> +       if (len)
> +               memcpy(sctx->buffer + partial, data, len);
> +}
> +
> +void early_sha1_final(struct sha1_state *sctx, u8 *out)
> +{
> +       const int bit_offset = SHA1_BLOCK_SIZE - sizeof(__be64);
> +       unsigned int partial = sctx->count % SHA1_BLOCK_SIZE;
> +       __be64 *bits = (__be64 *)(sctx->buffer + bit_offset);
> +       __be32 *digest = (__be32 *)out;
> +       int i;
> +
> +       sctx->buffer[partial++] = 0x80;
> +       if (partial > bit_offset) {
> +               memset(sctx->buffer + partial, 0x0, SHA1_BLOCK_SIZE - partial);
> +               partial = 0;
> +
> +               __sha_transform(sctx->state, sctx->buffer);
> +       }
> +
> +       memset(sctx->buffer + partial, 0x0, bit_offset - partial);
> +       *bits = cpu_to_be64(sctx->count << 3);
> +       __sha_transform(sctx->state, sctx->buffer);
> +
> +       for (i = 0; i < SHA1_DIGEST_SIZE / sizeof(__be32); i++)
> +               put_unaligned_be32(sctx->state[i], digest++);
> +
> +       *sctx = (struct sha1_state){};
> +}

If we're going to add SHA1 then this should go into lib/crypto
just like SHA2.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt