From 1b514239e85965cc4df085180a73dd91733135f7 Mon Sep 17 00:00:00 2001 From: Lorenz Bauer Date: Mon, 29 Jun 2020 10:56:25 +0100 Subject: bpf: flow_dissector: Check value of unused flags to BPF_PROG_ATTACH Using BPF_PROG_ATTACH on a flow dissector program supports neither target_fd, attach_flags or replace_bpf_fd but accepts any value. Enforce that all of them are zero. This is fine for replace_bpf_fd since its presence is indicated by BPF_F_REPLACE. It's more problematic for target_fd, since zero is a valid fd. Should we want to use the flag later on we'd have to add an exception for fd 0. The alternative is to force a value like -1. This requires more changes to tests. There is also precedent for using 0, since bpf_iter uses this for target_fd as well. Fixes: b27f7bb590ba ("flow_dissector: Move out netns_bpf prog callbacks") Signed-off-by: Lorenz Bauer Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200629095630.7933-2-lmb@cloudflare.com --- kernel/bpf/net_namespace.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c index 7a34a8caf954..03045f45afec 100644 --- a/kernel/bpf/net_namespace.c +++ b/kernel/bpf/net_namespace.c @@ -209,6 +209,9 @@ int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog) struct net *net; int ret; + if (attr->target_fd || attr->attach_flags || attr->replace_bpf_fd) + return -EINVAL; + type = to_netns_bpf_attach_type(attr->attach_type); if (type < 0) return -EINVAL; -- cgit