Re: [PATCH] verify: search keyid in hashed signature subpackets

[Ignat Korchagin]

Is this going to 2.02? I think it should, because it is a bug.

On Thu, Apr 21, 2016 at 5:54 PM, Ignat Korchagin <address@hidden> wrote:
> Best of both worlds: I left the READBUF_SIZE as is for the rest of the code, 
> but rather reallocate the buffer with appropriate length for subpackets 
> specifically. Hashing is outside of the keyid search function, so the name is 
> good this time.
>
> Still did not get your response about PGP private test key. If it is not 
> available, I can regenerate it and resign all test files for future use.
>
> diff --git a/grub-core/commands/verify.c b/grub-core/commands/verify.c
> index 4268eaa..91e1da6 100644
> --- a/grub-core/commands/verify.c
> +++ b/grub-core/commands/verify.c
> @@ -445,6 +445,38 @@
>    return ret;
>  }
>
> +static grub_uint64_t
> +grub_subpacket_keyid_search (const grub_uint8_t * sub, grub_ssize_t sub_len)
> +{
> +  const grub_uint8_t *ptr;
> +  grub_uint32_t l;
> +  grub_uint64_t keyid = 0;
> +
> +  for (ptr = sub; ptr < sub + sub_len; ptr += l)
> +    {
> +      if (*ptr < 192)
> +       l = *ptr++;
> +      else if (*ptr < 255)
> +       {
> +         if (ptr + 1 >= sub + sub_len)
> +           break;
> +         l = (((ptr[0] & ~192) << GRUB_CHAR_BIT) | ptr[1]) + 192;
> +         ptr += 2;
> +       }
> +      else
> +       {
> +         if (ptr + 5 >= sub + sub_len)
> +           break;
> +         l = grub_be_to_cpu32 (grub_get_unaligned32 (ptr + 1));
> +         ptr += 5;
> +       }
> +      if (*ptr == 0x10 && l >= 8)
> +       keyid = grub_get_unaligned64 (ptr + 1);
> +    }
> +
> +  return keyid;
> +}
> +
>  static grub_err_t
>  grub_verify_signature_real (char *buf, grub_size_t size,
>                             grub_file_t f, grub_file_t sig,
> @@ -529,20 +561,31 @@
>             break;
>           hash->write (context, readbuf, r);
>         }
> +    grub_free (readbuf);
> +
> +    readbuf = grub_malloc (rem);
> +    if (!readbuf)
> +      goto fail;
>
>      hash->write (context, &v, sizeof (v));
>      hash->write (context, &v4, sizeof (v4));
> -    while (rem)
> +
> +    r = 0;
> +    while (r < rem)
>        {
> -       r = grub_file_read (sig, readbuf,
> -                           rem < READBUF_SIZE ? rem : READBUF_SIZE);
> -       if (r < 0)
> +       grub_ssize_t rr = grub_file_read (sig, readbuf + r, rem - r);
> +       if (rr < 0)
>           goto fail;
> -       if (r == 0)
> +       if (rr == 0)
>           break;
> -       hash->write (context, readbuf, r);
> -       rem -= r;
> +       r += rr;
>        }
> +    if (r != rem)
> +      goto fail;
> +    hash->write (context, readbuf, rem);
> +    keyid = grub_subpacket_keyid_search (readbuf, rem);
> +    grub_free (readbuf);
> +
>      hash->write (context, &v, sizeof (v));
>      s = 0xff;
>      hash->write (context, &s, sizeof (s));
> @@ -550,40 +593,34 @@
>      r = grub_file_read (sig, &unhashed_sub, sizeof (unhashed_sub));
>      if (r != sizeof (unhashed_sub))
>        goto fail;
> -    {
> -      grub_uint8_t *ptr;
> -      grub_uint32_t l;
> -      rem = grub_be_to_cpu16 (unhashed_sub);
> -      if (rem > READBUF_SIZE)
> -       goto fail;
> -      r = grub_file_read (sig, readbuf, rem);
> -      if (r != rem)
> -       goto fail;
> -      for (ptr = readbuf; ptr < readbuf + rem; ptr += l)
> -       {
> -         if (*ptr < 192)
> -           l = *ptr++;
> -         else if (*ptr < 255)
> -           {
> -             if (ptr + 1 >= readbuf + rem)
> -               break;
> -             l = (((ptr[0] & ~192) << GRUB_CHAR_BIT) | ptr[1]) + 192;
> -             ptr += 2;
> -           }
> -         else
> -           {
> -             if (ptr + 5 >= readbuf + rem)
> -               break;
> -             l = grub_be_to_cpu32 (grub_get_unaligned32 (ptr + 1));
> -             ptr += 5;
> -           }
> -         if (*ptr == 0x10 && l >= 8)
> -           keyid = grub_get_unaligned64 (ptr + 1);
> -       }
> -    }
> +    rem = grub_be_to_cpu16 (unhashed_sub);
> +    readbuf = grub_malloc (rem);
> +    if (!readbuf)
> +      goto fail;
> +
> +    r = 0;
> +    while (r < rem)
> +      {
> +       grub_ssize_t rr = grub_file_read (sig, readbuf + r, rem - r);
> +       if (rr < 0)
> +         goto fail;
> +       if (rr == 0)
> +         break;
> +       r += rr;
> +      }
> +    if (r != rem)
> +      goto fail;
> +
> +    if (keyid == 0)
> +      keyid = grub_subpacket_keyid_search (readbuf, rem);
> +    grub_free (readbuf);
>
>      hash->final (context);
>
> +    readbuf = grub_zalloc (READBUF_SIZE);
> +    if (!readbuf)
> +      goto fail;
> +
>      grub_dprintf ("crypt", "alive\n");
>
>      hval = hash->read (context);
>