Subject: Re: [PATCH RFC 0/9] socket filtering using nf_tables

From: Pablo Neira Ayuso <[email-masked]>
Date: Sat, 15 Mar 2014 20:03:01 +0100

On Fri, Mar 14, 2014 at 09:04:50PM -0700, Alexei Starovoitov wrote:
[...]
> In the patches I sent, ebpf is _not_ exposed to the user.

>>From your last patch: http://patchwork.ozlabs.org/patch/329713/

diff --git a/include/uapi/linux/filter.h b/include/uapi/linux/filter.h
index 8eb9ccaa5b48..4e98fe16ba88 100644
--- a/include/uapi/linux/filter.h
+++ b/include/uapi/linux/filter.h
@@ -1,5 +1,6 @@ 
 /*
  * Linux Socket Filter Data Structures
+ * Extended BPF is Copyright (c) 2011-2014, PLUMgrid, http://plumgrid.com
  */
 
 #ifndef _UAPI__LINUX_FILTER_H__
@@ -19,7 +20,7 @@ 
  *     Try and keep these values and structures similar to BSD,
  *     especially
  *     the BPF code definitions which need to match so you can share
  *     filters
  */
- 
+
 struct sock_filter {   /* Filter block */
        __u16   code;   /* Actual filter code */
        __u8    jt;     /* Jump true */
@@ -27,6 +28,14 @@  struct sock_filter {        /* Filter block */
        __u32   k;      /* Generic multiuse field */
 };
 
+struct sock_filter_ext {
+       __u8    code;    /* opcode */
+       __u8    a_reg:4; /* dest register */
+       __u8    x_reg:4; /* source register */
+       __s16   off;     /* signed offset */
+       __s32   imm;     /* signed immediate constant */
+};
+
 struct sock_fprog {    /* Required for SO_ATTACH_FILTER. */
        unsigned short          len;    /* Number of filter blocks */
        struct sock_filter __user *filter;

That sock_filter_ext structure is exposed to userspace as well as many
other new BPF_* macros that you have defined.