On 03/10/2015 09:25 AM, Gupta Ruchika-R66431 wrote: > Hi York, > >> -----Original Message----- >> From: Sun York-R58495 >> Sent: Tuesday, March 10, 2015 9:45 PM >> To: Rana Gaurav-B46163; u-boot@lists.denx.de >> Cc: Wood Scott-B07421; Gupta Ruchika-R66431; Bansal Aneesh-B39320 >> Subject: Re: [PATCH] Add bootscript support to esbc_validate. >> >> >> >> On 03/10/2015 01:38 AM, Gaurav Rana wrote: >>> 1. Default environment will be used for secure boot flow which can't >>> be edited or saved. >>> 2. Command for secure boot is predefined in the default environment >>> which will run on autoboot (and autoboot is the only option allowed >>> in case of secure boot) and it looks like this: >>> #define CONFIG_SECBOOT \ >>> "setenv bs_hdraddr 0xe8e00000;" \ >>> "esbc_validate $bs_hdraddr;" \ >>> "source $img_addr;" \ >>> "esbc_halt;" >>> #endif >>> 3. Boot Script can contain esbc_validate commands and bootm command. >>> Uboot source command used in default secure boot command will run >>> the bootscript. >>> 4. Command esbc_halt added to ensure either bootm executes after >>> validation of images or core should just spin. >>> >> What's the purpose of "esbc_halt"? Once it enters the spin, how to get it >> out? > The purpose of bootscript is to validate the next level images and then pass > control to it, so bootscript must contain a bootm command. We don't expect > control to return back to u-boot. Hence a command esbc_halt is introduced > which would make the core spin and not provide uboot prompt in case > bootscript doesn't pass control to next level image. > For secure chain of trust, only validated bootscript should be allowed to > execute and be responsible for passing control to next level image. >
Ruchika, Do you expect secure boot to run automatically once u-boot reaches the prompt and the "source $img_addr" to actually boot the OS? You put "esbc_halt" as a fall-back to catch failure above? It doesn't sounds very secure to me. I am hoping other reviewers can chime in and give comments. York _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
