Re: [edk2-devel] [PATCH v4 0/7] CryptoPkg: Upgrade OpenSSL to 1.1.1b

["Ard Biesheuvel" <ard.biesheuvel@linaro.org>]

On Tue, 21 May 2019 at 13:23, Laszlo Ersek <lersek@redhat.com> wrote:
>
> Hi,
>
> On 05/21/19 11:09, Wang, Jian J wrote:
> > Ard,
> >
> >> -----Original Message-----
> >> From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of Ard
> >> Biesheuvel
> >> Sent: Tuesday, May 21, 2019 5:02 PM
> >> To: Wang, Jian J <jian.j.wang@intel.com>
> >> Cc: devel@edk2.groups.io; Laszlo Ersek <lersek@redhat.com>; Lu, XiaoyuX
> >> <xiaoyux.lu@intel.com>; Ye, Ting <ting.ye@intel.com>; Leif Lindholm
> >> <leif.lindholm@linaro.org>; Gao, Liming <liming.gao@intel.com>
> >> Subject: Re: [edk2-devel] [PATCH v4 0/7] CryptoPkg: Upgrade OpenSSL to 1.1.1b
> >>
> >> On Tue, 21 May 2019 at 09:43, Wang, Jian J <jian.j.wang@intel.com> wrote:
> >>>
> >>> Hi Ard,
> >>>
> >>> Any comments?
> >>>
> >>> Regards,
> >>> Jian
> >>>
> >>>> -----Original Message-----
> >>>> From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of
> >> Wang,
> >>>> Jian J
> >>>> Sent: Monday, May 20, 2019 9:41 AM
> >>>> To: devel@edk2.groups.io; ard.biesheuvel@linaro.org; Laszlo Ersek
> >>>> <lersek@redhat.com>
> >>>> Cc: Lu, XiaoyuX <xiaoyux.lu@intel.com>; Ye, Ting <ting.ye@intel.com>; Leif
> >>>> Lindholm <leif.lindholm@linaro.org>; Gao, Liming <liming.gao@intel.com>
> >>>> Subject: Re: [edk2-devel] [PATCH v4 0/7] CryptoPkg: Upgrade OpenSSL to
> >> 1.1.1b
> >>>>
> >>>> Ard,
> >>>>
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of
> >> Ard
> >>>>> Biesheuvel
> >>>>> Sent: Friday, May 17, 2019 11:06 PM
> >>>>> To: Laszlo Ersek <lersek@redhat.com>
> >>>>> Cc: Wang, Jian J <jian.j.wang@intel.com>; devel@edk2.groups.io; Lu,
> >> XiaoyuX
> >>>>> <xiaoyux.lu@intel.com>; Ye, Ting <ting.ye@intel.com>; Leif Lindholm
> >>>>> <leif.lindholm@linaro.org>; Gao, Liming <liming.gao@intel.com>
> >>>>> Subject: Re: [edk2-devel] [PATCH v4 0/7] CryptoPkg: Upgrade OpenSSL to
> >>>> 1.1.1b
> >>>>>
> >>>>> On Fri, 17 May 2019 at 15:17, Laszlo Ersek <lersek@redhat.com> wrote:
> >>>>>>
> >>>>>> On 05/17/19 15:04, Laszlo Ersek wrote:
> >>>>>>> On 05/17/19 07:11, Wang, Jian J wrote:
> >>>>>>>> Hi Laszlo,
> >>>>>>>>
> >>>>>>>> There's already a float library used in OpensslLib.inf.
> >>>>>>>>
> >>>>>>>> [LibraryClasses.ARM]
> >>>>>>>>   ArmSoftFloatLib
> >>>>>>>>
> >>>>>>>> The problem is that the below instance doesn't implement
> >> __aeabi_ui2d
> >>>>>>>> and __aeabi_d2uiz (I encountered this one as well)
> >>>>>>>>
> >>>>>>>>   ArmPkg\Library\ArmSoftFloatLib\ArmSoftFloatLib.inf
> >>>>>>>>
> >>>>>>>> I think we can update this library support those two APIs. So what
> >> about
> >>>>>>>> we still push the patch and file a BZ to fix this issue?
> >>>>>>>
> >>>>>>> I'm OK with that, but it will break ARM and AARCH64 platforms that
> >>>>>>> consume OpensslLib (directly or through BaseCryptLib), so this question
> >>>>>>> is up to Leif and Ard to decide.
> >>>>>>
> >>>>>> Correction: break ARM platforms only, not AARCH64.
> >>>>>>
> >>>>>
> >>>>> We obviously need to fix this before we can upgrade to a new OpenSSL
> >> version.
> >>>>>
> >>>>> Do we really have a need for the random functions? These seem the only
> >>>>> ones that use floating point, which the UEFI spec does not permit, so
> >>>>> it would be better if we could fix this by removing the dependency on
> >>>>> FP in the first place (and get rid of ArmSoftFloatLib entirely)
> >>>>>
> >>>>
> >>>> BaseCryptLib provides RandSeed/RandBytes interface which wrap openssl
> >> rand
> >>>> functionalities. These interfaces are used by following components in edk2
> >>>>
> >>>>   - CryptoPkg\Library\TlsLib\TlsInit.c
> >>>>   - SecurityPkg\HddPassword\HddPasswordDxe.c
> >>>>
> >>>> Openssl components, like asn1, bn, evp, ocsp, pem, pkcs7, pkcs12, rsa, ssl (in
> >>>> addition
> >>>> to cms, dsa, srp, which are disabled in edk2) will call rand_* interface as well.
> >>>>
> >>
> >> If we have both internal (to Openssl) and external users of the RNG
> >> api, then I guess there is no way to work around this. It is
> >> unfortunate, since the RNG code in OpenSSL doesn't actually use double
> >> types except for keeping an entropy count, which could just as easily
> >> be kept in an integer variable.
>
> (1) I think I agree... However, it seems that the first function (or one
> of the first functions) in OpenSSL to take an "entropy" parameter, of
> type "double", was RAND_add(). And the RAND_add() manual states,
>
>        RAND_add() mixes the num bytes at buf into the PRNG state.
>        Thus, if the data at buf are unpredictable to an adversary,
>        this increases the uncertainty about the state and makes the
>        PRNG output less predictable. Suitable input comes from user
>        interaction (random key presses, mouse movements) and certain
>        hardware events. The entropy argument is (the lower bound of)
>        an estimate of how much randomness is contained in buf,
>        measured in bytes. Details about sources of randomness and how
>        to estimate their entropy can be found in the literature, e.g.
>        RFC 1750.
>
> I've now looked up RFC 1750, and it contains copious amounts of math on
> irrational numbers. Hence the use of floating point in OpenSSL, I'd guess.
>
>   https://www.ietf.org/rfc/rfc1750.txt
>
> ... After digging a bit in the OpenSSL git history, I've found the
> following commit (from 19 years ago):
>
> commit 853f757ecea74a271a7c5cdee3f3b5fe0d3ae863
> Author: Bodo Möller <bodo@openssl.org>
> Date:   Sat Feb 19 15:22:53 2000 +0000
>
>     Allow for higher granularity of entropy estimates by using 'double'
>     instead of 'unsigned' counters.
>     Seed PRNG in MacOS/GetHTTPS.src/GetHTTPS.cpp.
>
>     Partially submitted by Yoram Meroz <yoram@mail.idrive.com>.
>
> It was the commit with
>
> -void RAND_add(const void *buf,int num,int entropy);
> +void RAND_add(const void *buf,int num,double entropy);
>
> FWIW, the "PRNG" reference at the end of the commit message seems
> meaningless. Check for yourself:
>
> $ git show 853f757ecea7:MacOS/GetHTTPS.src/GetHTTPS.cpp
>
> The fact that "entropy" is now of type "double" does not seem to be put
> to use, anywhere in that file.
>
> I'll send a query to the openssl-users mailing list, just so we
> understand better.
>

Thanks for doing the paleontological research here.

However, the outcome of this query is not going to affect our short
term issue with this code.

I will try to come back to this issue as soon as I can, but I am a bit
swamped at the moment.




>
> >> So we will need to fix ArmSoftFloatLib before we can merge this
> >> OpenSSL update.
>
> (2) NB, I think we can no longer merge this feature for
> edk2-stable201905. The soft feature freeze criterion is that all patches
> be reviewed (approved) on-list before the SFF date / announcement, and
> that was not fulfilled in this case.
>
>
> >> I'm happy to help doing that, could you please
> >> summarize what we are missing today?
> >>
> >
> > Great. I think there're two intrinsic functions missing here
> >
> >   __aeabi_ui2d
> >   __aeabi_d2uiz
> >
> > Laszlo, please double check if these two are enough.
>
> (3) I can only report the failure that trips up the build for me. I did
> that here:
>
> http://mid.mail-archive.com/049e489c-b58f-0fc5-1c66-8ad920d93979@redhat.com
> https://edk2.groups.io/g/devel/message/40823
>
>
> Thus, for me, the missing symbol was "__aeabi_ui2d".
>
> It's possible that the 32-bit ARM build will fail at a different (later)
> stage as well, but I can't tell until I get past this one. (And I don't
> think I can implement a "shim" function for the missing symbol, just to
> let the build progress.)
>
> Thanks,
> Laszlo
>
> > Thanks for doing this.
> >
> > Regards,
> > Jian
> >
> >> 
> >
>