[U-Boot] [PATCH] rsa: read out public_exponent value based on 32-bit alignment

[Ooi, Joyce]

> -----Original Message-----
> From: Marek Vasut [mailto:marex at denx.de]
> Sent: Friday, December 28, 2018 6:05 PM
> To: Ooi, Joyce <joyce.ooi at intel.com>; Michal Simek
> <michal.simek at xilinx.com>; Siva Durga Prasad Paladugu
> <siva.durga.paladugu at xilinx.com>
> Cc: u-boot at lists.denx.de; See, Chin Liang <chin.liang.see at intel.com>; Chee,
> Tien Fong <tien.fong.chee at intel.com>; Tan, Ley Foon
> <ley.foon.tan at intel.com>
> Subject: Re: [PATCH] rsa: read out public_exponent value based on 32-bit
> alignment
> 
> On 12/28/18 8:30 AM, Ooi, Joyce wrote:
> > Hi Marek,
> 
> Hi,
> 
> > Any comments about this?
> 
> Use get_unaligned() ?
It seems that if USE_HOSTCC is enabled, get_unaligned_* can't be used.

In lib/rsa/rsa-mod-exp.c,
#ifndef USE_HOSTCC
..
#include <asm/unaligned.h>
#else
#include "fdt_host.h"
#include "mkimage.h"
#include <fdt_support.h>
#endif

So, to make it more generic (with or without USE_HOSTCC enabled), I read out
the public_exponent as two 32-bit datas and then concatenating them into a
64-bit data.
> 
> > Thanks,
> > Joyce Ooi
> >
> >> -----Original Message-----
> >> From: Ooi, Joyce
> >> Sent: Saturday, December 8, 2018 4:18 PM
> >> To: Marek Vasut <marex at denx.de>; Michal Simek
> >> <michal.simek at xilinx.com>; Siva Durga Prasad Paladugu
> >> <siva.durga.paladugu at xilinx.com>
> >> Cc: u-boot at lists.denx.de; Ooi, Joyce <joyce.ooi at intel.com>; See, Chin
> >> Liang <chin.liang.see at intel.com>; Chee, Tien Fong
> >> <tien.fong.chee at intel.com>; Tan, Ley Foon <ley.foon.tan at intel.com>
> >> Subject: [PATCH] rsa: read out public_exponent value based on 32-bit
> >> alignment
> >>
> >> Public_exponent is a 64-bit data, which is stored in the device tree
> >> blob in a 32- bit alignment address. This causes a problem for ARM64
> >> when public_exponent is read out one shot as a 64-bit data from an
> >> unaligned address. Hence, to solve this problem, public_exponent is
> >> read out as two 32-bit datas, and then concatenating them.
> >>
> >> Signed-off-by: Ooi, Joyce <joyce.ooi at intel.com>
> >> ---
> >>  lib/rsa/rsa-mod-exp.c |    6 ++++--
> >>  1 files changed, 4 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/lib/rsa/rsa-mod-exp.c b/lib/rsa/rsa-mod-exp.c index
> >> 9d78aa1..3eace38 100644
> >> --- a/lib/rsa/rsa-mod-exp.c
> >> +++ b/lib/rsa/rsa-mod-exp.c
> >> @@ -252,6 +252,9 @@ int rsa_mod_exp_sw(const uint8_t *sig, uint32_t
> >> sig_len,  {
> >>  	struct rsa_public_key key;
> >>  	int ret;
> >> +	uint64_t exponent =
> >> +		(uint64_t)(*((uint32_t *)(prop->public_exponent + 4))) << 32 |
> >> +		*((uint32_t *)(prop->public_exponent));
> >>
> >>  	if (!prop) {
> >>  		debug("%s: Skipping invalid prop", __func__); @@ -263,8
> >> +266,7 @@ int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len,
> >>  	if (!prop->public_exponent)
> >>  		key.exponent = RSA_DEFAULT_PUBEXP;
> >>  	else
> >> -		key.exponent =
> >> -			fdt64_to_cpu(*((uint64_t *)(prop->public_exponent)));
> >> +		key.exponent = fdt64_to_cpu(exponent);
> >>
> >>  	if (!key.len || !prop->modulus || !prop->rr) {
> >>  		debug("%s: Missing RSA key info", __func__);
> >> --
> >> 1.7.1
> >
> 
> 
> --
> Best regards,
> Marek Vasut