linux-kernel - [PATCH bpf 1/2] flow_dissector: reject invalid attach

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Date:   Fri, 12 Jun 2020 17:01:40 +0100
From:   Lorenz Bauer <lmb@...udflare.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Sitnicki <jakub@...udflare.com>
Cc:     kernel-team@...udflare.com, Lorenz Bauer <lmb@...udflare.com>,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH bpf 1/2] flow_dissector: reject invalid attach_flags

Using BPF_PROG_ATTACH on a flow dissector program supports neither flags
nor target_fd but accepts any value. Return EINVAL if either are non-zero.

Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
Fixes: b27f7bb590ba ("flow_dissector: Move out netns_bpf prog callbacks")
---
 kernel/bpf/net_namespace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c
index 78cf061f8179..56133e78ae4f 100644
--- a/kernel/bpf/net_namespace.c
+++ b/kernel/bpf/net_namespace.c
@@ -192,6 +192,9 @@ int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 	struct net *net;
 	int ret;
 
+	if (attr->attach_flags || attr->target_fd)
+		return -EINVAL;
+
 	type = to_netns_bpf_attach_type(attr->attach_type);
 	if (type < 0)
 		return -EINVAL;
-- 
2.25.1