Messages in this thread | | | Date | Wed, 04 Jul 2007 14:29:59 -0700 | From | Andrew Morgan <> | Subject | Re: implement-file-posix-capabilities.patch |
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Serge E. Hallyn wrote: > 1. Exactly Andrew describes. Once userspace switches to a new cap > format, an older kernel simply won't support them
Mmm. Let me see. I think I prefer this one! :-)
> 2. As Andrew describes, but also encode the version number into the > capability name, i.e. security.capability.v3. Now userspace can > optionally tack on more than one capability version to be backward > compatible.
If you have a significant legacy of use of earlier versions, I guess this makes sense. However, given the experimental nature of this support (it will be a while before the user space support for this is secure/robust), I'm not all that concerned about legacy support.
> 3. Somewhat different than Andrew describes. We mandate that any > capability version N+1 consist of > > struct vfs_cap_data { > __u32 magic; > capability_version_1; > capability_version_2; > ... > capability_version_N; > capability_version_N+1; > };
Ugh. I don't like this. It presumes that the kernel will get more and more complicated over time. Please don't do this one.
> Or, for brevity, > > struct vfs_cap_data { > __u32 first_magic; > __u32 last_magic; > capability_version_first; > ... > capability_version_last; > }; > > 4. Stick to the current plan, where switching to 64-bit caps will be > done as > > struct vfs_cap_data_disk { > __le32 version; > __le32 data[]; /* eff[0], perm[0], inh[0], eff[1], ... */ > };
While asserting that it is more flexible etc., no one has yet actually given an example of where fE being richer than a simple binary helps anything. Until I see an example, I'm going to hold the position that this is needless "complexity".
Cheers
Andrew
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