amd/picasso/verstage: replace rsa accel with modexp
Replace vb2ex_hwcrypto_rsa_verify_digest with vb2ex_hwcrypto_modexp.
Instead of using hardware acceleration for whole RSA process,
acclerating only calculation part(modexp) increases transparency
without affecting boot time.
BUG=b:169157796
BRANCH=zork
TEST=build and flash, check time spent on RSA is not changed
Change-Id: I085f043bf2014615d2c9db6df0b7947ee84b9546
Signed-off-by: Kangheui Won <khwon@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45987
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/amd/picasso/psp_verstage/vboot_crypto.c b/src/soc/amd/picasso/psp_verstage/vboot_crypto.c
index 0bb9066..d9364d0 100644
--- a/src/soc/amd/picasso/psp_verstage/vboot_crypto.c
+++ b/src/soc/amd/picasso/psp_verstage/vboot_crypto.c
@@ -8,6 +8,7 @@
#include "psp_verstage.h"
#include <stddef.h>
#include <string.h>
+#include <swab.h>
#include <vb2_api.h>
static struct SHA_GENERIC_DATA_T sha_op;
@@ -103,48 +104,50 @@
return VB2_SUCCESS;
}
-vb2_error_t vb2ex_hwcrypto_rsa_verify_digest(const struct vb2_public_key *key,
- const uint8_t *sig, const uint8_t *digest)
+vb2_error_t vb2ex_hwcrypto_modexp(const struct vb2_public_key *key,
+ uint8_t *inout,
+ uint32_t *workbuf32, int exp)
{
- RSAPKCS_VERIFY_PARAMS RSAParams;
+ /* workbuf32 is guaranteed to be a length of
+ * 3 * key->arrsize * sizeof(uint32_t).
+ * Since PSP expects everything in LE and *inout is BE array,
+ * we'll use workbuf for temporary buffer for endian conversion.
+ */
+ MOD_EXP_PARAMS mod_exp_param;
+ unsigned int key_bytes = key->arrsize * sizeof(uint32_t);
+ uint32_t *sig_swapped = workbuf32;
+ uint32_t *output_buffer = &workbuf32[key->arrsize];
+ uint32_t *inout_32 = (uint32_t *)inout;
uint32_t retval;
- uint32_t exp = 65537;
- uint32_t sig_size;
- size_t digest_size;
+ uint32_t i;
- /* PSP only supports 2K and 4K RSA */
+ /* PSP only supports 2K and 4K moduli */
if (key->sig_alg != VB2_SIG_RSA2048 &&
key->sig_alg != VB2_SIG_RSA2048_EXP3 &&
key->sig_alg != VB2_SIG_RSA4096) {
return VB2_ERROR_EX_HWCRYPTO_UNSUPPORTED;
}
- /* PSP only supports SHA256, SHA384 and SHA512*/
- if (key->hash_alg != VB2_HASH_SHA256 &&
- key->hash_alg != VB2_HASH_SHA384 &&
- key->hash_alg != VB2_HASH_SHA512) {
- return VB2_ERROR_EX_HWCRYPTO_UNSUPPORTED;
- }
+ for (i = 0; i < key->arrsize; i++)
+ sig_swapped[i] = swab32(inout_32[key->arrsize - i - 1]);
- if (key->sig_alg == VB2_SIG_RSA2048_EXP3)
- exp = 3;
- sig_size = vb2_rsa_sig_size(key->sig_alg);
- digest_size = vb2_digest_size(key->hash_alg);
+ mod_exp_param.pExponent = (char *)&exp;
+ mod_exp_param.ExpSize = sizeof(exp);
+ mod_exp_param.pModulus = (char *)key->n;
+ mod_exp_param.ModulusSize = key_bytes;
+ mod_exp_param.pMessage = (char *)sig_swapped;
+ mod_exp_param.pOutput = (char *)output_buffer;
- RSAParams.pHash = (char *)digest;
- RSAParams.HashLen = digest_size;
- RSAParams.pModulus = (char *)key->n;
- RSAParams.ModulusSize = sig_size;
- RSAParams.pExponent = (char *)&exp;
- RSAParams.ExpSize = sizeof(exp);
- RSAParams.pSig = (char *)sig;
-
- retval = svc_rsa_pkcs_verify(&RSAParams);
+ retval = svc_modexp(&mod_exp_param);
if (retval) {
printk(BIOS_ERR, "ERROR: HW crypto failed - errorcode: %#x\n",
retval);
- return VB2_ERROR_RSA_VERIFY_DIGEST;
+ return VB2_ERROR_EX_HWCRYPTO_UNSUPPORTED;
}
+ /* vboot expects results in *inout with BE, so copy & convert. */
+ for (i = 0; i < key->arrsize; i++)
+ inout_32[i] = swab32(output_buffer[key->arrsize - i - 1]);
+
return VB2_SUCCESS;
}