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From: Lorenz Bauer <lmb@cloudflare.com>
To: ast@kernel.org, daniel@iogearbox.net, sdf@google.com,
	jakub@cloudflare.com, john.fastabend@gmail.com
Cc: kernel-team@cloudflare.com, bpf@vger.kernel.org,
	Lorenz Bauer <lmb@cloudflare.com>
Subject: [PATCH bpf v2 1/6] bpf: flow_dissector: check value of unused flags to BPF_PROG_ATTACH
Date: Mon, 29 Jun 2020 10:56:25 +0100
Message-ID: <20200629095630.7933-2-lmb@cloudflare.com> (raw)
In-Reply-To: <20200629095630.7933-1-lmb@cloudflare.com>

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.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.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 3e89c7ad42cb..bf18eabeaea2 100644
--- a/kernel/bpf/net_namespace.c
+++ b/kernel/bpf/net_namespace.c
@@ -217,6 +217,9 @@ 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;
-- 
2.25.1


  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-29  9:56 [PATCH bpf v2 0/6] Fix attach / detach uapi for sockmap and flow_dissector Lorenz Bauer
2020-06-29  9:56 ` Lorenz Bauer [this message]
2020-06-29  9:56 ` [PATCH bpf v2 2/6] bpf: flow_dissector: check value of unused flags to BPF_PROG_DETACH Lorenz Bauer
2020-06-29  9:56 ` [PATCH bpf v2 3/6] bpf: sockmap: check value of unused args to BPF_PROG_ATTACH Lorenz Bauer
2020-06-29  9:56 ` [PATCH bpf v2 4/6] bpf: sockmap: require attach_bpf_fd when detaching a program Lorenz Bauer
2020-07-08  1:30   ` Martin KaFai Lau
2020-06-29  9:56 ` [PATCH bpf v2 5/6] selftests: bpf: pass program and target_fd in flow_dissector_reattach Lorenz Bauer
2020-06-29  9:56 ` [PATCH bpf v2 6/6] selftests: bpf: pass program to bpf_prog_detach in flow_dissector Lorenz Bauer
2020-06-30  5:48 ` [PATCH bpf v2 0/6] Fix attach / detach uapi for sockmap and flow_dissector Yonghong Song
2020-06-30  8:39   ` Lorenz Bauer
2020-06-30 15:08     ` Yonghong Song
2020-06-30 15:50       ` Lorenz Bauer
2020-06-30 18:00 ` Alexei Starovoitov
2020-06-30 18:31   ` Jakub Sitnicki
2020-06-30 18:42     ` Alexei Starovoitov
2020-07-01  7:45       ` Jakub Sitnicki

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