Messages in this thread | | | From | Kees Cook <> | Date | Tue, 30 Oct 2018 14:49:21 -0700 | Subject | Re: [PATCH v8 1/2] seccomp: add a return code to trap to userspace |
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On Mon, Oct 29, 2018 at 3:40 PM, Tycho Andersen <tycho@tycho.ws> wrote: > * switch to a flags based future-proofing mechanism for struct > seccomp_notif and seccomp_notif_resp, thus avoiding version issues > with structure length (Kees) [...] > > +struct seccomp_notif { > + __u64 id; > + __u32 pid; > + __u32 flags; > + struct seccomp_data data; > +}; > + > +struct seccomp_notif_resp { > + __u64 id; > + __s64 val; > + __s32 error; > + __u32 flags; > +};
Hrm, so, what's the plan for when struct seccomp_data changes size? I'm realizing that it might be "too late" for userspace to discover it's running on a newer kernel. i.e. it gets a user notification, and discovers flags it doesn't know how to handle. Do we actually need both flags AND a length? Designing UAPI is frustrating! :)
Do we need another ioctl to discover the seccomp_data size maybe?
-- Kees Cook
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