Re: [PATCH v6 06/14] x86: Add early SHA support for Secure Launch early measurements

[Daniel P. Smith]

On 5/10/23 23:33, Herbert Xu wrote:
> Ross Philipson <ross.philipson@xxxxxxxxxx> 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.

As mentioned before, this patch mimicked an early version for SHA2. We 
were remiss in not keeping it aligned with how the SHA2 evolved. I will 
take a closer look, but these wrappers may be able to go away and be 
reduced to just an include as SHA2 does these days.

v/r,
dps