Messages in this thread Patch in this message | | | Date | Wed, 12 Dec 2007 15:06:17 -0800 | From | Andrew Morgan <> | Subject | Re: [RFC] [PATCH -mm] oom_kill: remove uid==0 checks |
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Serge E. Hallyn wrote: > Andrew, I've cc:d you here bc in doing this patch I noticed that your > 64-bit capabilities patch switched this code from an explicit check > of cap_t(p->cap_effective) to using __capable(). That means that > now being glossed over by the oom killer means PF_SUPERPRIV will > be set. Is that intentional?
Yes, I switched the check because the old one didn't work with the new capability representation.
However, I had not thought this aspect of this replacement through. At the time, it seemed obvious but in this case it actually depends on whether you think using privilege (PF_SUPERPRIV) means "benefited from privilege", or "successfully completed a privileged operation".
I suspect, in this case, the correct thing to do is add the equivalent of:
#define CAPABLE_PROBE_ONLY(a,b) (!security_capable(a,b))
and use that in the code in question. That is, return to the old behavior in a way that will not break if we ever need to add more bits.
Thanks for finding this.
Cheers
Andrew
> > Signed-off-by: Serge Hallyn <serue@us.ibm.com> > --- > mm/oom_kill.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 016127e..9fd8d5d 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -128,7 +128,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime, > * Superuser processes are usually more important, so we make it > * less likely that we kill those. > */ > - if (__capable(p, CAP_SYS_ADMIN) || p->uid == 0 || p->euid == 0) > + if (__capable(p, CAP_SYS_ADMIN) || __capable(p, CAP_SYS_RESOURCE)) > points /= 4; > > /*
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