Re: [PATCH net-next] net: filter: rename 'struct sk_filter' to 'struct bpf_prog'

On Fri, Jul 25, 2014 at 01:25:35PM +0200, Daniel Borkmann wrote:

[ also Cc'ing Willem, Pablo ]

On 07/25/2014 10:04 AM, Alexei Starovoitov wrote:

quoted

'sk_filter' name is used as 'struct sk_filter', function sk_filter() and
as variable 'sk_filter', which makes code hard to read.
Also it's easily confused with 'struct sock_filter'
Rename 'struct sk_filter' to 'struct bpf_prog' to clarify semantics and
align the name with generic BPF use model.

Agreed, as we went for kernel/bpf/, renaming makes absolutely sense.

My nft socket filtering changes are accomodated into struct sk_filter,
and will still be, so I still need some generic name there...

Please, leave this as it is.

quoted

The only ugly place is uapi/linux/netfilter/xt_bpf.h which
managed to expose kernel internal structure into uapi header.
Though it shouldn't even compile in user space, preserve the mess by
adding empty 'struct sk_filter;' there and type cast it to 'struct bpf_prog'
inside kernel in net/netfilter/xt_bpf.c

Signed-off-by: Alexei Starovoitov <redacted>
---

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.

You can just send me a patch to change it to void. It's an internal
kernel pointer as the comment states. There is **no** way that
userspace can lurk with that from iptables at all.