Re: [PATH bpf-next 2/2] selftests/bpf: Check that flow dissector can be re-attached
From: Stanislav Fomichev <sdf@fomichev.me>
Date: 2019-10-09 16:33:44
Also in:
bpf
On 10/09, Jakub Sitnicki wrote:
Make sure a new flow dissector program can be attached to replace the old one with a single syscall. Also check that attaching the same program twice is prohibited.
Overall the series looks good, left a bunch of nits/questions below.
quoted hunk ↗ jump to hunk
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> --- .../bpf/prog_tests/flow_dissector_reattach.c | 93 +++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/flow_dissector_reattach.cdiff --git a/tools/testing/selftests/bpf/prog_tests/flow_dissector_reattach.c b/tools/testing/selftests/bpf/prog_tests/flow_dissector_reattach.c new file mode 100644 index 000000000000..0f0006c93956 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/flow_dissector_reattach.c@@ -0,0 +1,93 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Test that the flow_dissector program can be updated with a single + * syscall by attaching a new program that replaces the existing one. + * + * Corner case - the same program cannot be attached twice. + */ +#include <errno.h> +#include <fcntl.h> +#include <stdbool.h> +#include <unistd.h> + +#include <linux/bpf.h> +#include <bpf/bpf.h> + +#include "test_progs.h" +
[..]
+/* Not used here. For CHECK macro sake only. */ +static int duration;
nit: you can use CHECK_FAIL macro instead which doesn't require this.
if (CHECK_FAIL(expr)) {
printf("something bad has happened\n");
return/goto;
}
It may be more verbose than doing CHECK() with its embedded error
message, so I leave it up to you to decide on whether you want to switch
to CHECK_FAIL or stick to CHECK.
+static bool is_attached(void)
+{
+ bool attached = true;
+ int err, net_fd = -1;nit: maybe don't need to initialize net_fd to -1 here as well.
+ __u32 cnt;
+
+ net_fd = open("/proc/self/ns/net", O_RDONLY);
+ if (net_fd < 0)
+ goto out;
+
+ err = bpf_prog_query(net_fd, BPF_FLOW_DISSECTOR, 0, NULL, NULL, &cnt);
+ if (CHECK(err, "bpf_prog_query", "ret %d errno %d\n", err, errno))
+ goto out;
+
+ attached = (cnt > 0);
+out:
+ close(net_fd);
+ return attached;
+}
+
+static int load_prog(void)
+{
+ struct bpf_insn prog[] = {
+ BPF_MOV64_IMM(BPF_REG_0, BPF_OK),
+ BPF_EXIT_INSN(),
+ };
+ int fd;
+
+ fd = bpf_load_program(BPF_PROG_TYPE_FLOW_DISSECTOR, prog,
+ ARRAY_SIZE(prog), "GPL", 0, NULL, 0);
+ CHECK(fd < 0, "bpf_load_program", "ret %d errno %d\n", fd, errno);
+
+ return fd;
+}
+
+void test_flow_dissector_reattach(void)
+{
+ int prog_fd[2] = { -1, -1 };
+ int err;
+
+ if (is_attached())
+ return;Should we call test__skip() here to indicate that the test has been skipped? Also, do we need to run this test against non-root namespace as well?
+ prog_fd[0] = load_prog(); + if (prog_fd[0] < 0) + return; + + prog_fd[1] = load_prog(); + if (prog_fd[1] < 0) + goto out_close; + + err = bpf_prog_attach(prog_fd[0], 0, BPF_FLOW_DISSECTOR, 0); + if (CHECK(err, "bpf_prog_attach-0", "ret %d errno %d\n", err, errno)) + goto out_close; + + /* Expect success when attaching a different program */ + err = bpf_prog_attach(prog_fd[1], 0, BPF_FLOW_DISSECTOR, 0); + if (CHECK(err, "bpf_prog_attach-1", "ret %d errno %d\n", err, errno)) + goto out_detach; + + /* Expect failure when attaching the same program twice */ + err = bpf_prog_attach(prog_fd[1], 0, BPF_FLOW_DISSECTOR, 0); + CHECK(!err || errno != EINVAL, "bpf_prog_attach-2", + "ret %d errno %d\n", err, errno); + +out_detach: + err = bpf_prog_detach(0, BPF_FLOW_DISSECTOR); + CHECK(err, "bpf_prog_detach", "ret %d errno %d\n", err, errno); + +out_close: + close(prog_fd[1]); + close(prog_fd[0]); +} -- 2.20.1