Messages in this thread | | | Date | Mon, 10 Aug 2009 10:30:06 +0800 | From | Amerigo Wang <> | Subject | Re: [Patch v3] vfs: allow file truncations when both suid and write permissions set |
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OGAWA Hirofumi wrote: > Eric Paris <eparis@redhat.com> writes: > > >>>> I was thinking about this and kept telling myself I was going to test v2 >>>> before I ack/nak. Clearly we shouldn't for the dropping of SUID if the >>>> process didn't have permission to change the ATTR_SIZE. >>>> >>>> Acked-by: Eric Paris <eparis@redhat.com> >>>> >>> BTW, Do you know why doesn't security modules fix the handling of >>> do_truncate() (i.e. ATTR_MODE | ATTR_SIZE). And why doesn't it allow to >>> pass ATTR_FORCE for it? >>> >> I'm not sure what you mean. I understood ATTR_FORCE to mean 'I am magic >> and get to override all security checks." Which is why nothing should >> ever be using ATTR_FORCE with things other than SUID. >> >> I guess we could somehow force logic into the LSM to make it only apply >> to SUID and friends but I'm not sure it buys us anything. >> > > Yes, I think it's good way. Don't we want to do the following? > > if (permission check of job) > return error; > if (do job at once) > return error; > > But currently way is, > > if (permission check of first part) > return error > if (do first part of job) > return error > if (permission check of second part) > return error > if (do second part of job) > return error > > So, if second part was error, we may want to undo the job of first part > in theory. But, to undo is just hard and strange. >
Yeah, the problem is currently we don't have such wrappers, only notify_change(). :-/
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