From 9beb8bedb05c5f3a353dba62b8fa7cbbb9ec685e Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Sat, 9 Sep 2017 01:40:35 +0200 Subject: bpf: make error reporting in bpf_warn_invalid_xdp_action more clear Differ between illegal XDP action code and just driver unsupported one to provide better feedback when we throw a one-time warning here. Reason is that with 814abfabef3c ("xdp: add bpf_redirect helper function") not all drivers support the new XDP return code yet and thus they will fall into their 'default' case when checking for return codes after program return, which then triggers a bpf_warn_invalid_xdp_action() stating that the return code is illegal, but from XDP perspective it's not. I decided not to place something like a XDP_ACT_MAX define into uapi i) given we don't have this either for all other program types, ii) future action codes could have further encoding there, which would render such define unsuitable and we wouldn't be able to rip it out again, and iii) we rarely add new action codes. Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- net/core/filter.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'net/core') diff --git a/net/core/filter.c b/net/core/filter.c index 0848df2..3a50a9b 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3609,7 +3609,11 @@ static bool xdp_is_valid_access(int off, int size, void bpf_warn_invalid_xdp_action(u32 act) { - WARN_ONCE(1, "Illegal XDP return value %u, expect packet loss\n", act); + const u32 act_max = XDP_REDIRECT; + + WARN_ONCE(1, "%s XDP return value %u, expect packet loss!\n", + act > act_max ? "Illegal" : "Driver unsupported", + act); } EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action); -- cgit v1.1