[PATCH bpf-next v3 5/5] selftests: bpf: test writable buffers in raw tps

Matt Mullins
2019-04-19T21:06:08Z

This tests that:
* a BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE cannot be attached if it
uses either:
* a variable offset to the tracepoint buffer, or
* an offset beyond the size of the tracepoint buffer
* a tracer can modify the buffer provided when attached to a writable
tracepoint in bpf_prog_test_run

Signed-off-by: Matt Mullins <mmullins@fb.com>
---
include/trace/events/bpf_test_run.h | 50 ++++++++++++
net/bpf/test_run.c | 4 +
.../raw_tp_writable_reject_nbd_invalid.c | 40 ++++++++++
.../bpf/prog_tests/raw_tp_writable_test_run.c | 80 +++++++++++++++++++
.../selftests/bpf/verifier/raw_tp_writable.c | 34 ++++++++
5 files changed, 208 insertions(+)
create mode 100644 include/trace/events/bpf_test_run.h
create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
create mode 100644 tools/testing/selftests/bpf/verifier/raw_tp_writable.c

diff --git a/include/trace/events/bpf_test_run.h b/include/trace/events/bpf_test_run.h
new file mode 100644
index 000000000000..abf466839ea4
--- /dev/null
+++ b/include/trace/events/bpf_test_run.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM bpf_test_run
+
+#if !defined(_TRACE_NBD_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_BPF_TEST_RUN_H
+
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(bpf_test_finish,
+
+ TP_PROTO(int *err),
+
+ TP_ARGS(err),
+
+ TP_STRUCT__entry(
+ __field(int, err)
+ ),
+
+ TP_fast_assign(
+ __entry->err = *err;
+ ),
+
+ TP_printk("bpf_test_finish with err=%d", __entry->err)
+);
+
+#ifdef DEFINE_EVENT_WRITABLE
+#undef BPF_TEST_RUN_DEFINE_EVENT
+#define BPF_TEST_RUN_DEFINE_EVENT(template, call, proto, args, size) \
+ DEFINE_EVENT_WRITABLE(template, call, PARAMS(proto), \
+ PARAMS(args), size)
+#else
+#undef BPF_TEST_RUN_DEFINE_EVENT
+#define BPF_TEST_RUN_DEFINE_EVENT(template, call, proto, args, size) \
+ DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args))
+#endif
+
+BPF_TEST_RUN_DEFINE_EVENT(bpf_test_finish, bpf_test_finish,
+
+ TP_PROTO(int *err),
+
+ TP_ARGS(err),
+
+ sizeof(int)
+);
+
+#endif
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index fab142b796ef..25e757102595 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -13,6 +13,9 @@
#include <net/sock.h>
#include <net/tcp.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/bpf_test_run.h>
+
static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
u32 *retval, u32 *time)
{
@@ -100,6 +103,7 @@ static int bpf_test_finish(const union bpf_attr *kattr,
if (err != -ENOSPC)
err = 0;
out:
+ trace_bpf_test_finish(&err);
return err;
}

diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
new file mode 100644
index 000000000000..328d5c4b084b
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include <linux/nbd.h>
+
+void test_raw_tp_writable_reject_nbd_invalid(void)
+{
+ __u32 duration = 0;
+ char error[4096];
+ int bpf_fd = -1, tp_fd = -1;
+
+ const struct bpf_insn program[] = {
+ /* r6 is our tp buffer */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_6, 128),
+ BPF_EXIT_INSN(),
+ };
+
+ struct bpf_load_program_attr load_attr = {
+ .prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
+ .license = "GPL v2",
+ .insns = program,
+ .insns_cnt = sizeof(program) / sizeof(struct bpf_insn),
+ .log_level = 2,
+ };
+
+ bpf_fd = bpf_load_program_xattr(&load_attr, error, sizeof(error));
+ if (CHECK(bpf_fd < 0, "bpf_raw_tracepoint_writable loaded",
+ "failed: %d errno %d\n", bpf_fd, errno))
+ return;
+
+ tp_fd = bpf_raw_tracepoint_open("nbd_send_request", bpf_fd);
+ if (CHECK(tp_fd >= 0, "bpf_raw_tracepoint_writable opened",
+ "erroneously succeeded\n"))
+ goto out_bpffd;
+
+ close(tp_fd);
+out_bpffd:
+ close(bpf_fd);
+}
diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
new file mode 100644
index 000000000000..4145925f9cab
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include <linux/nbd.h>
+
+void test_raw_tp_writable_test_run(void)
+{
+ __u32 duration = 0;
+ char error[4096];
+
+ const struct bpf_insn trace_program[] = {
+ BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
+ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6, 0),
+ BPF_LD_IMM64(BPF_REG_0, 42),
+ BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+
+ struct bpf_load_program_attr load_attr = {
+ .prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
+ .license = "GPL v2",
+ .insns = trace_program,
+ .insns_cnt = sizeof(trace_program) / sizeof(struct bpf_insn),
+ .log_level = 2,
+ };
+
+ int bpf_fd = bpf_load_program_xattr(&load_attr, error, sizeof(error));
+ if (CHECK(bpf_fd < 0, "bpf_raw_tracepoint_writable loaded",
+ "failed: %d errno %d\n", bpf_fd, errno))
+ return;
+
+ const struct bpf_insn skb_program[] = {
+ BPF_LD_IMM64(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+
+ struct bpf_load_program_attr skb_load_attr = {
+ .prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
+ .license = "GPL v2",
+ .insns = skb_program,
+ .insns_cnt = sizeof(skb_program) / sizeof(struct bpf_insn),
+ };
+
+ int filter_fd =
+ bpf_load_program_xattr(&skb_load_attr, error, sizeof(error));
+ if (CHECK(filter_fd < 0, "test_program_loaded", "failed: %d errno %d\n",
+ filter_fd, errno))
+ goto out_bpffd;
+
+ int tp_fd = bpf_raw_tracepoint_open("bpf_test_finish", bpf_fd);
+ if (CHECK(tp_fd < 0, "bpf_raw_tracepoint_writable opened",
+ "failed: %d errno %d\n", tp_fd, errno))
+ goto out_filterfd;
+
+ char test_skb[128] = {
+ 0,
+ };
+
+ __u32 prog_ret;
+ int err = bpf_prog_test_run(filter_fd, 1, test_skb, sizeof(test_skb), 0,
+ 0, &prog_ret, 0);
+ CHECK(err != 42, "test_run",
+ "tracepoint did not modify return value\n");
+ CHECK(prog_ret != 0, "test_run_ret",
+ "socket_filter did not return 0\n");
+
+ close(tp_fd);
+
+ err = bpf_prog_test_run(filter_fd, 1, test_skb, sizeof(test_skb), 0, 0,
+ &prog_ret, 0);
+ CHECK(err != 0, "test_run_notrace",
+ "test_run failed with %d errno %d\n", err, errno);
+ CHECK(prog_ret != 0, "test_run_ret_notrace",
+ "socket_filter did not return 0\n");
+
+out_filterfd:
+ close(filter_fd);
+out_bpffd:
+ close(bpf_fd);
+}
diff --git a/tools/testing/selftests/bpf/verifier/raw_tp_writable.c b/tools/testing/selftests/bpf/verifier/raw_tp_writable.c
new file mode 100644
index 000000000000..95b5d70a1dc1
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/raw_tp_writable.c
@@ -0,0 +1,34 @@
+{
+ "raw_tracepoint_writable: reject variable offset",
+ .insns = {
+ /* r6 is our tp buffer */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
+
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ /* move the key (== 0) to r10-8 */
+ BPF_MOV32_IMM(BPF_REG_0, 0),
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_0, 0),
+ /* lookup in the map */
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+ BPF_FUNC_map_lookup_elem),
+
+ /* exit clean if null */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+ BPF_EXIT_INSN(),
+
+ /* shift the buffer pointer to a variable location */
+ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0),
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_6, BPF_REG_0),
+ /* clobber whatever's there */
+ BPF_MOV64_IMM(BPF_REG_7, 4242),
+ BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_7, 0),
+
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_hash_8b = { 1, },
+ .prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
+ .errstr = "R6 invalid variable buffer offset: off=0, var_off=(0x0; 0xffffffff)",
+},
--
2.17.1