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authorStanislav Fomichev <sdf@google.com>2019-04-22 08:55:49 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2019-04-23 18:36:34 +0200
commitc9cb2c1e11cee75b3af5699add3302a3997f78e4 (patch)
tree5223f0713124af66fc29f16bedae1c16c38a717f /tools
parentc43f1255b866b423d2381f77eaa2cbc64a9c49aa (diff)
downloadlinux-c9cb2c1e11cee75b3af5699add3302a3997f78e4.tar.bz2
selftests/bpf: add flow dissector bpf_skb_load_bytes helper test
When flow dissector is called without skb, we want to make sure bpf_skb_load_bytes invocations return error. Add small test which tries to read single byte from a packet. bpf_skb_load_bytes should always fail under BPF_PROG_TEST_RUN because it was converted to the skb-less mode. Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/bpf/prog_tests/flow_dissector_load_bytes.c48
1 files changed, 48 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/flow_dissector_load_bytes.c b/tools/testing/selftests/bpf/prog_tests/flow_dissector_load_bytes.c
new file mode 100644
index 000000000000..dc5ef155ec28
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/flow_dissector_load_bytes.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+void test_flow_dissector_load_bytes(void)
+{
+ struct bpf_flow_keys flow_keys;
+ __u32 duration = 0, retval, size;
+ struct bpf_insn prog[] = {
+ // BPF_REG_1 - 1st argument: context
+ // BPF_REG_2 - 2nd argument: offset, start at first byte
+ BPF_MOV64_IMM(BPF_REG_2, 0),
+ // BPF_REG_3 - 3rd argument: destination, reserve byte on stack
+ BPF_ALU64_REG(BPF_MOV, BPF_REG_3, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -1),
+ // BPF_REG_4 - 4th argument: copy one byte
+ BPF_MOV64_IMM(BPF_REG_4, 1),
+ // bpf_skb_load_bytes(ctx, sizeof(pkt_v4), ptr, 1)
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+ BPF_FUNC_skb_load_bytes),
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2),
+ // if (ret == 0) return BPF_DROP (2)
+ BPF_MOV64_IMM(BPF_REG_0, BPF_DROP),
+ BPF_EXIT_INSN(),
+ // if (ret != 0) return BPF_OK (0)
+ BPF_MOV64_IMM(BPF_REG_0, BPF_OK),
+ BPF_EXIT_INSN(),
+ };
+ int fd, err;
+
+ /* make sure bpf_skb_load_bytes is not allowed from skb-less context
+ */
+ fd = bpf_load_program(BPF_PROG_TYPE_FLOW_DISSECTOR, prog,
+ ARRAY_SIZE(prog), "GPL", 0, NULL, 0);
+ CHECK(fd < 0,
+ "flow_dissector-bpf_skb_load_bytes-load",
+ "fd %d errno %d\n",
+ fd, errno);
+
+ err = bpf_prog_test_run(fd, 1, &pkt_v4, sizeof(pkt_v4),
+ &flow_keys, &size, &retval, &duration);
+ CHECK(size != sizeof(flow_keys) || err || retval != 1,
+ "flow_dissector-bpf_skb_load_bytes",
+ "err %d errno %d retval %d duration %d size %u/%zu\n",
+ err, errno, retval, duration, size, sizeof(flow_keys));
+
+ if (fd >= -1)
+ close(fd);
+}