[PATCH 5.9 146/255] tools/bpftool: Fix attaching flow dissector

Greg Kroah-Hartman
2020-11-17T13:48:27Z

From: Lorenz Bauer <lmb@cloudflare.com>

[ Upstream commit f9b7ff0d7f7a466a920424246e7ddc2b84c87e52 ]

My earlier patch to reject non-zero arguments to flow dissector attach
broke attaching via bpftool. Instead of 0 it uses -1 for target_fd.
Fix this by passing a zero argument when attaching the flow dissector.

Fixes: 1b514239e859 ("bpf: flow_dissector: Check value of unused flags to BPF_PROG_ATTACH")
Reported-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20201105115230.296657-1-lmb@cloudflare.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/bpf/bpftool/prog.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index d393eb8263a60..994506540e564 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -741,7 +741,7 @@ static int parse_attach_detach_args(int argc, char **argv, int *progfd,
}

if (*attach_type == BPF_FLOW_DISSECTOR) {
- *mapfd = -1;
+ *mapfd = 0;
return 0;
}

--
2.27.0