Messages in this thread | | | From | "Michael Kerrisk (man-pages)" <> | Date | Sun, 9 Dec 2012 10:54:30 +0100 | Subject | Re: [PATCH] Document how capability bits work |
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Andy,
On Sat, Dec 8, 2012 at 2:27 AM, Andy Lutomirski <luto@amacapital.net> wrote: > On Fri, Dec 7, 2012 at 5:10 PM, Rob Landley <rob@landley.net> wrote: >> On 12/07/2012 01:32:18 PM, Andy Lutomirski wrote: >>> >>> On Fri, Dec 7, 2012 at 11:21 AM, Serge Hallyn >>> <serge.hallyn@canonical.com> wrote: >>> > Quoting Andy Lutomirski (luto@amacapital.net): >>> >> Signed-off-by: Andy Lutomirski <luto@amacapital.net> >>> >> --- >>> >> Documentation/security/capabilities.txt | 161 >>> >> ++++++++++++++++++++++++++++++++ >>> >> 1 file changed, 161 insertions(+) >>> >> create mode 100644 Documentation/security/capabilities.txt >>> > >>> > TBH, I think a pointer to the capabilities.7 man page would be better. >>> > (plus, if you feel they are needed, updates to the man page) >>> >>> Updating capabilities.7 wouldn't be a bad idea, but IMO it certainly >>> needs work. For example, it says: >> >> ... >> >>> I would be happy to revise this patch to reference capabilities.7. >> >> >> The capabilities.7 man page is existing maintained documentation on how to >> use this from userspace, which seems to be the point of your document. >> Having include/linux/uapi/capability.h mention its existence might be good. >> Feeding fixes to the documentation we've already got would be good. >> >> I read your document having largely ignored capabilities for years, and >> don't feel I have a better understanding of them after reading it. (I'm >> aware they exist, I'm aware they're used as a justification for extended >> attributes, I'm aware people think breaking a fireplace into a bunch of >> candleflames increases fire safety. I'm aware of >> http://forums.grsecurity.net/viewtopic.php?f=7&t=2522 and I _used_ to be >> aware of >> http://userweb.kernel.org/~morgan/sendmail-capabilities-war-story.html but >> kernel.org never bothered putting most of itself back together after the >> breakin last year and archive.org doesn't have a copy. I'm aware that a >> decade ago at Atlanta Linux Showcase in california Ted Tso was sad nobody >> was using them yet. But I haven't hugely been tracking changes over the last >> 5 years in how they work. It looks like figuring out who has what involves >> working through exercises in set theory that cannot be explained using a 127 >> bit ascii set. Personally, I prefer "more dangerous" security setups that >> don't require I pull out scratch paper to reason about the state of the >> system, so perhaps I'm biased here.) > > Heh. I agree this stuff is shockingly complicated. (And this > document isn't wriiten in ASCII...) > > I actually wrote this file because I was reading the code and trying > to figure out wtf was going on. This is the result :) I'll see if I > can improve capabilities.7. > > Any pointers to things you wanted to understand?
Indeed, it strikes me that a patch to capabilities.7 would be best. This is all about user-visible stuff, and hiding things in a kernel source file is not very user visible.
capabilities.7 is a big page. It would be best to break the patch into logically distinct pieces, if that can be sensibly done.
Cheers,
Michael
-- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/
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