> -----Original Message-----
> From: Stephen Warren [mailto:[email protected]]
> Sent: Wednesday, October 07, 2015 9:34 AM
> To: Jimmy Zhang
> Cc: Allen Martin; Stephen Warren; [email protected]
> Subject: Re: [tegrarcm PATCH v2 2/4] Add support for update pubkey and
> rsa-pss signatures
>
> On 10/02/2015 02:56 PM, Jimmy Zhang wrote:
> > Create new configuration keywords:
> > RsaKeyModulusFile: pubkey modulus
> > RsaPssSigBlFile: bootloader rsa pss signature
> > RsaPssSigBctFile: bct rsa pss signature
> >
> > Sample Configuration file update_bl_sig.cfg
> > RsaKeyModulusFile = pubkey.mod;
> > RsaPssSigBlFile = bl.sig;
> >
> > where pubkey.mod and bl.sig are files that contain the public key
> > modulus and bootloader's rsa-pss signature respectively.
> >
> > public key modulus and signature are created through utilities outside
> > cbootimage.
> >
> > Command line example:
> > $ cbootimage -s tegra210 -u update_bl_sig.cfg image.bin
> > image.bin-bl-signed
> >
> > Above three new keywords added in this CL are only implemented support
> > for T210.
>
> > diff --git a/src/cbootimage.h b/src/cbootimage.h
>
> > +#define ARSE_RSA_MAX_MODULUS_SIZE 2048
> > +#define ARSE_RSA_PARAM_MAX_BYTES
> (ARSE_RSA_MAX_MODULUS_SIZE / 8)
>
> These values are currently defined in the chip-specific location
> src/tNNN/nvboot_bct_tNNN.h, and this patch only removes a single on of
> those 3 copies when creating this new centralized value. At best that makes
> the code inconsistent, and at worst could cause compile errors due to
> multiple definitions.
>
> Instead, can you leave this value in the T210-specific location. More related
> to this below.
In this case we can't use get_value() because it returns the value. What we
need here is the size of value. Will add function * get_value_size().
>
> > diff --git a/src/parse.c b/src/parse.c
>
> > +static int parse_rsa_param(build_image_context *context,
> > + parse_token token,
> > + char *rest)
> > +{
> > + char filename[MAX_BUFFER];
> > +
> > + assert(context != NULL);
> > + assert(rest != NULL);
> > +
> > + if (context->generate_bct != 0)
> > + return 0;
> > +
> > + /* Parse the file name. */
> > + rest = parse_filename(rest, filename, MAX_BUFFER);
> > + if (rest == NULL)
> > + return 1;
>
> That doesn't look like the correct error check. Rather, other function that
> parse filenames (and other fields) appear to do something like the following
> after parsing all the fields:
>
> /* Parse the end state. */
> rest = parse_end_state(rest, e_state, MAX_STR_LEN);
> if (rest == NULL)
> return 1;
>
> I suspect that code should be present in this function too?
>
Here I basically followed function parse_bct_file().
Function parse_end_state() is called in preparing for scanning next string
"Complete". It doesn't apply to this case.
Error checking only checks whether a terminator is found or not.
> > diff --git a/src/set.c b/src/set.c
>
> > +int
> > +set_rsa_param(build_image_context *context, parse_token token,
> > + char *filename)
> > +{
> > + int result;
> > + u_int8_t *rsa_storage; /* Holds the rsa param after reading */
> > + u_int32_t actual_size; /* In bytes */
> > + file_type rsa_filetype = file_type_bin;
> > +
> > + /* Read the image into memory. */
> > + result = read_from_image(filename,
> > + 0,
> > + ARSE_RSA_PARAM_MAX_BYTES,
> > + &rsa_storage,
> > + &actual_size,
> > + rsa_filetype);
> > +
> > + if (result) {
> > + printf("Error reading file %s.\n", filename);
> > + exit(1);
> > + }
> > +
> > + if (actual_size != ARSE_RSA_PARAM_MAX_BYTES) {
> > + printf("Error: invalid size, file %s.\n", filename);
> > + exit(1);
> > + }
>
> I would suggest removing anything from this function that restricts the file
> size to any particular value, since this is generic code, and in theory at
> least
> each SoC defines its own RSA size parameters.
>
> Looks like an indentation error there too.
>
> > diff --git a/src/t210/nvbctlib_t210.c b/src/t210/nvbctlib_t210.c
>
> > @@ -2198,6 +2201,24 @@ t210_bct_set_value(parse_token id, void *data,
> u_int8_t *bct)
> > memcpy(&bct_ptr->unique_chip_id, data,
> sizeof(nvboot_ecid));
> > break;
> >
> > + case token_rsa_key_modulus:
> > + memcpy(&bct_ptr->key, data,
> sizeof(nvboot_rsa_key_modulus));
> > + break;
> > +
> > + case token_rsa_pss_sig_bl:
> > + /*
> > + * Update bootloader 0 since there is only one copy
> > + * of bootloader being built in.
> > + */
> > + memcpy(&bct_ptr->bootloader[0].signature.rsa_pss_sig,
> > + data, sizeof(nvboot_rsa_pss_sig));
> > + break;
> > +
> > + case token_rsa_pss_sig_bct:
> > + memcpy(&bct_ptr->signature.rsa_pss_sig,
> > + data, sizeof(nvboot_rsa_pss_sig));
> > + break;
>
> Instead, I think the file size can be validated here?
>
> Hmm, I don't see a size parameter to this function:-(
>
> Given that, I think that either:
>
> a) Add a size parameter to this function. This has the disadvantage of
> needing to update a bunch of call sites. I don't know how many; perhaps this
> isn't a big deal?
>
> or:
>
> b) Modify set_rsa_param() so that it doesn't check the file size against a
> single global define ARSE_RSA_PARAM_MAX_BYTES, but rather calls a
> function that's implemented in src/t210/*.c that tells it what size the token
> should be.
>
> This would also solve my other objection that currently set_rsa_param()
> assumes that all the RSA-related parameters must be the same size. While
> that is true at present, I'm not sure that it my be true in all cases in the
> future.
>
> This is probably the most flexible, and not too hard to implement.
>
> or:
>
> c) Remove the duplicate defines (e.g. ARSE_RSA_MAX_MODULUS_SIZE)
> from the T114/124/132 files too. This has the disadvantage that if some
> future chip changes the RSA sizes, we'll have to undo this change at that
> time, and switch back to (a) or (b).
Will implement option b.
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