From ea02f9411d9faa3553ed09ce0ec9f00ceae9885e Mon Sep 17 00:00:00 2001 From: Michal Sekletar Date: Fri, 17 Jan 2014 17:09:45 +0100 Subject: net: introduce SO_BPF_EXTENSIONS For user space packet capturing libraries such as libpcap, there's currently only one way to check which BPF extensions are supported by the kernel, that is, commit aa1113d9f85d ("net: filter: return -EINVAL if BPF_S_ANC* operation is not supported"). For querying all extensions at once this might be rather inconvenient. Therefore, this patch introduces a new option which can be used as an argument for getsockopt(), and allows one to obtain information about which BPF extensions are supported by the current kernel. As David Miller suggests, we do not need to define any bits right now and status quo can just return 0 in order to state that this versions supports SKF_AD_PROTOCOL up to SKF_AD_PAY_OFFSET. Later additions to BPF extensions need to add their bits to the bpf_tell_extensions() function, as documented in the comment. Signed-off-by: Michal Sekletar Cc: David Miller Reviewed-by: Daniel Borkmann Signed-off-by: David S. Miller --- include/linux/filter.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/linux/filter.h') diff --git a/include/linux/filter.h b/include/linux/filter.h index ff4e40cd45b1..1a95a2dcf113 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -83,6 +83,17 @@ static inline void bpf_jit_free(struct sk_filter *fp) #define SK_RUN_FILTER(FILTER, SKB) sk_run_filter(SKB, FILTER->insns) #endif +static inline int bpf_tell_extensions(void) +{ + /* When adding new BPF extension it is necessary to enumerate + * it here, so userspace software which wants to know what is + * supported can do so by inspecting return value of this + * function + */ + + return 0; +} + enum { BPF_S_RET_K = 1, BPF_S_RET_A, -- cgit v1.2.3