Messages in this thread | | | Date | Fri, 25 Jul 2014 10:27:14 -0700 | Subject | Re: [PATCH net-next] net: filter: rename 'struct sk_filter' to 'struct bpf_prog' | From | Alexei Starovoitov <> |
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On Fri, Jul 25, 2014 at 6:53 AM, Willem de Bruijn <willemb@google.com> wrote: >>> >alternative fix for xt_bpf.h could be to replace: >>> > /* only used in the kernel */ >>> > struct sk_filter *filter __attribute__((aligned(8))); >>> >with >>> > /* only used in the kernel */ >>> > void *filter __attribute__((aligned(8))); >>> > >>> >but this 'void *' approach may further break broken userspace, >>> >whereas the fix implemented here is more seamless. >>> >>> Yep, that's not good, 'struct sk_filter' should never have been in a uapi >>> file actually. > > This follows a convention in include/uapi/linux/netfilter/*.h that > likely predates the introduction of uapi. A search for "Used > internally by the kernel" shows many more examples. I should not have > included filter.h, however. The common behavior when using pointers > to kernel-internal structures is to have a forward declaration. I suggest > making that change, instead of changing to void *. This avoids having > to add casts where xt_bpf_info is used in net/netfilter/xt_bpf.c:
that will not avoid typecast. Either 'void *' approach or extra 'struct sk_filter;' approach, both need type casts to 'struct bpf_prog' in xt_bpf.c (because of SK_RUN_FILTER macro) Therefore I prefer extra 'struct sk_filter;' approach.
> -#include <linux/filter.h> > #include <linux/types.h> > > #define XT_BPF_MAX_NUM_INSTR 64 > > +struct sk_filter; > + > struct xt_bpf_info { > > I can send this as a separate patch to net-next, if that helps.
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