Re: Hardening

[Alex Vong]

Hi,

Wow, this was long time ago. I've forgot this completely.

Ricardo Wurmus <address@hidden> writes:

> Leo Famulari <address@hidden> writes:
>
>> On Wed, Dec 30, 2015 at 05:06:30PM +0100, Ludovic Courtès wrote:
>>> Alex Vong <address@hidden> skribis:
>>> > Yes, I grep for `fstack-protector-strong' in the guix code base and no
>>> > matches are found. It appears no packages are setting this flag
>>> > currently. I think this flag (perhaps also a couple others) should be
>>> > set by default since they help protect against buffer overflow
>>> > <https://en.wikipedia.org/wiki/Buffer_overflow_protection>.
>>> 
>>> I definitely agree, that’s something I’ve been wanting to try out.
>>> 
>>> The question is more how.  Do we change the default #:configure-flags
>>> for ‘gnu-build-system’ to something like:
>>> 
>>>   '("CPPFLAGS=-D_FORTIFY_SOURCE=2"
>>>     "CFLAGS=-O2 -g -fstack-protector-strong")
>>> 
>>> ?
>>> 
>>> That sounds like a good starting point, but I expect that (1) one third
>>> of the packages will fail to build, and (2) another third of the
>>> packages will not get these flags, for instance because they pass their
>>> own #:configure-flags.
>>> 
>>> IOW, it will take a whole rebuild to find out exactly what’s going on
>>> and to fix any issues.
>>> 
>>> Would you like to start working on it?  Then we could create a branch,
>>> have Hydra build it, and incrementally fix things.
>>
>> We should pick this project back up. I was suprised to find we haven't
>> done anything like this after reading this recent blog post about Nix's
>> hardening effort:
>>
>> https://blog.mayflower.de/5800-Hardening-Compiler-Flags-for-NixOS.html?utm_source=twitterfeed&utm_medium=twitter
>
> Are the above flags the only flags we’d like to play with?  There’s no
> harm in letting hydra rebuild the world with these flags on a separate
> branch — provided that all build nodes are usable.
>
There are indeed additional flags (for debian's hardening).


Here is the complete output (from the testing distribution):

address@hidden:~$ DEB_BUILD_MAINT_OPTIONS=hardening=+all dpkg-buildflags
CFLAGS=-g -O2 -fdebug-prefix-map=/home/alexvong1995=. -fPIE 
-fstack-protector-strong -Wformat -Werror=format-security
CPPFLAGS=-Wdate-time -D_FORTIFY_SOURCE=2
CXXFLAGS=-g -O2 -fdebug-prefix-map=/home/alexvong1995=. -fPIE 
-fstack-protector-strong -Wformat -Werror=format-security
FCFLAGS=-g -O2 -fdebug-prefix-map=/home/alexvong1995=. -fPIE 
-fstack-protector-strong
FFLAGS=-g -O2 -fdebug-prefix-map=/home/alexvong1995=. -fPIE 
-fstack-protector-strong
GCJFLAGS=-g -O2 -fdebug-prefix-map=/home/alexvong1995=. -fPIE 
-fstack-protector-strong
LDFLAGS=-fPIE -pie -Wl,-z,relro -Wl,-z,now
OBJCFLAGS=-g -O2 -fdebug-prefix-map=/home/alexvong1995=. -fPIE 
-fstack-protector-strong -Wformat -Werror=format-security
OBJCXXFLAGS=-g -O2 -fdebug-prefix-map=/home/alexvong1995=. -fPIE 
-fstack-protector-strong -Wformat -Werror=format-security


The `-fdebug-prefix-map' flag seems to be using the current working
directory.

> ~~ Ricardo

Cheers,
Alex