Messages in this thread | | | Date | Sun, 16 May 1999 20:23:47 +0200 | From | Pavel Machek <> | Subject | Re: Capabilities done right [diff against 2.3.1] |
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Hi!
> > Next try with capabilities, this time against 2.3.1. Patch is completely > > safe and should significantly enhance system security. It is completely > > backward compatible: ie. no semantics change. Capabilities are > > implemented using elf notes (and this version parses notes correctly). > > Software exists for adding capabilities at runtime, so you don't even > > require a recompile. > > I'm not entirely convinced. The thing with ELF notes is that they only > work with ELF. That may sound obvious, and it is, but it makes me wonder > whether it's the right way at all.
Only other executables are a.out (nobody uses them these days) and scripts. But take a look: we do not honour setuid bit on scripts, anyway! It is perl interpretter who has s bit. So I do not think scripts are issue.
> I suspect that it would be cleaner to have capabilities be a name-space > issue rather than an inode issue. For example, the one thing I've always > wanted to do with symlinks is to have symlinks that can change the > privileges of the lookup - it's complex and maybe not a good idea, but > it's a more intriguing concept and works with shellscripts and other > systems where you can't add ELF notes..
Yes, going namespace would be nicer, but is _extremely hard_ as you would need to modify tools such as tar, cp, nfsd etc. And I doubt it will be usefull. As long as elf is only widespread executable format (and it is - sbit is not honoured for scripts and a.out is dead), I think this solution is pretty much ok.
Pavel -- I'm really pavel@ucw.cz. Look at http://195.113.31.123/~pavel. Pavel Hi! I'm a .signature virus! Copy me into your ~/.signature to help me spread!
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