Messages in this thread | | | Date | Wed, 24 Sep 2008 18:19:45 -0700 | From | Chris Wright <> | Subject | Re: [PATCH 2/2] file capabilities: remove CONFIG_SECURITY_FILE_CAPABILITIES |
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* Serge E. Hallyn (serue@us.ibm.com) wrote: > Quoting Chris Wright (chrisw@sous-sol.org): > > * Serge E. Hallyn (serue@us.ibm.com) wrote: > > > Remove the option to compile the kernel without file capabilities. Not > > > compiling file capabilities actually makes the kernel less safe, as it > > > includes the possibility for a task changing another task's capabilities. > > > > > > Some are concerned that userspace tools (and user education) are not > > > up to the task of properly configuring file capabilities on a system. > > > For those cases, there is now the ability to boot with the no_file_caps > > > boot option. This will prevent file capabilities from being used in > > > the capabilities recalculation at exec, but will not change the rest > > > of the kernel behavior which used to be switchable using the > > > CONFIG_SECURITY_FILE_CAPABILITIES option. > > > > (note: defconfig has CONFIG_SECURITY_FILE_CAPABILITIES=y) > > text data bss dec hex filename > > 6805157 1018344 671900 8495401 81a129 obj64-defconfig/vmlinux > > 6805151 1018368 671900 8495419 81a13b obj64-defconfig-patch1/vmlinux > > 6805151 1018368 671900 8495419 81a13b obj64-defconfig-patch2/vmlinux > > 6804605 1018344 671900 8494849 819f01 obj64-nofcap/vmlinux > > 6804604 1018344 671900 8494848 819f00 obj64-nofcap-patch1/vmlinux > > 6805150 1018368 671900 8495418 81a13a obj64-nofcap-patch2/vmlinux > > (what are you using to get these numbers?)
Just building w/ O=obj64... and then using "size obj64-*/vmlinux"
> > The last 2 show the real diff now, add 570 bytes by effectively forcing > > CONFIG_SECURITY_FILE_CAPABILITIES on. > > That surprises me - I thought a reasonable amount of code was cut as > well. Sounds like it may be worth it to refactor some of the code.
Be nice to cut it down if you can.
> > What is being done to enable userspace in distros to make those 570 > > bytes generally useful? > > Fedora 9 and ubuntu intrepid already have full capabilities support and > modern libcap. Sles is set to ship with a modern libcap, and according > to what Andreas is saying, if we can provide them with the no_file_caps > boot option then suse is willing to have a kernel with capabilities > turned on. I think gentoo still comes with libcap-1. Need to look into > changing that. > > I suppose the next baby-step will be to do get rid of setuid on little > things like ping. Actually using inheritable caps for pseudo-admin > 'roles' may be a bit farther off, and a particularly interesting problem > will be to take huge pieces of cross-os software like ssh which make > assumptions about setuid behavior, and find ways to make them work > correctly with capabilities, with capabilities in > SECURE_NOROOT|SECURE_NOSETUIDFIXUP, and with non-linux oses.
The baby step including simple things like setuid ping was the step I was thinking of. That w/ embedded and bloatwatch in mind is why I asked.
thanks, -chris
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