From: Andrii Nakryiko <andrii@kernel.org>
Date: Thu, 9 Dec 2021 11:38:38 -0800
Subject: selftests/bpf: Add test for libbpf's custom log_buf behavior
Patch-mainline: v5.17-rc1
Git-commit: 57e889269af3dd0609933e2550c4baee7a7eb84c
References: jsc#PED-1368
Add a selftest that validates that per-program and per-object log_buf
overrides work as expected. Also test same logic for low-level
bpf_prog_load() and bpf_btf_load() APIs.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-11-andrii@kernel.org
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
tools/testing/selftests/bpf/prog_tests/log_buf.c | 276 +++++++++++++++++++++++
tools/testing/selftests/bpf/progs/test_log_buf.c | 24 ++
2 files changed, 300 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/log_buf.c
create mode 100644 tools/testing/selftests/bpf/progs/test_log_buf.c
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/log_buf.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include <test_progs.h>
+#include <bpf/btf.h>
+
+#include "test_log_buf.skel.h"
+
+static size_t libbpf_log_pos;
+static char libbpf_log_buf[1024 * 1024];
+static bool libbpf_log_error;
+
+static int libbpf_print_cb(enum libbpf_print_level level, const char *fmt, va_list args)
+{
+ int emitted_cnt;
+ size_t left_cnt;
+
+ left_cnt = sizeof(libbpf_log_buf) - libbpf_log_pos;
+ emitted_cnt = vsnprintf(libbpf_log_buf + libbpf_log_pos, left_cnt, fmt, args);
+
+ if (emitted_cnt < 0 || emitted_cnt + 1 > left_cnt) {
+ libbpf_log_error = true;
+ return 0;
+ }
+
+ libbpf_log_pos += emitted_cnt;
+ return 0;
+}
+
+static void obj_load_log_buf(void)
+{
+ libbpf_print_fn_t old_print_cb = libbpf_set_print(libbpf_print_cb);
+ LIBBPF_OPTS(bpf_object_open_opts, opts);
+ const size_t log_buf_sz = 1024 * 1024;
+ struct test_log_buf* skel;
+ char *obj_log_buf, *good_log_buf, *bad_log_buf;
+ int err;
+
+ obj_log_buf = malloc(3 * log_buf_sz);
+ if (!ASSERT_OK_PTR(obj_log_buf, "obj_log_buf"))
+ return;
+
+ good_log_buf = obj_log_buf + log_buf_sz;
+ bad_log_buf = obj_log_buf + 2 * log_buf_sz;
+ obj_log_buf[0] = good_log_buf[0] = bad_log_buf[0] = '\0';
+
+ opts.kernel_log_buf = obj_log_buf;
+ opts.kernel_log_size = log_buf_sz;
+ opts.kernel_log_level = 4; /* for BTF this will turn into 1 */
+
+ /* In the first round every prog has its own log_buf, so libbpf logs
+ * don't have program failure logs
+ */
+ skel = test_log_buf__open_opts(&opts);
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ goto cleanup;
+
+ /* set very verbose level for good_prog so we always get detailed logs */
+ bpf_program__set_log_buf(skel->progs.good_prog, good_log_buf, log_buf_sz);
+ bpf_program__set_log_level(skel->progs.good_prog, 2);
+
+ bpf_program__set_log_buf(skel->progs.bad_prog, bad_log_buf, log_buf_sz);
+ /* log_level 0 with custom log_buf means that verbose logs are not
+ * requested if program load is successful, but libbpf should retry
+ * with log_level 1 on error and put program's verbose load log into
+ * custom log_buf
+ */
+ bpf_program__set_log_level(skel->progs.bad_prog, 0);
+
+ err = test_log_buf__load(skel);
+ if (!ASSERT_ERR(err, "unexpected_load_success"))
+ goto cleanup;
+
+ ASSERT_FALSE(libbpf_log_error, "libbpf_log_error");
+
+ /* there should be no prog loading log because we specified per-prog log buf */
+ ASSERT_NULL(strstr(libbpf_log_buf, "-- BEGIN PROG LOAD LOG --"), "unexp_libbpf_log");
+ ASSERT_OK_PTR(strstr(libbpf_log_buf, "prog 'bad_prog': BPF program load failed"),
+ "libbpf_log_not_empty");
+ ASSERT_OK_PTR(strstr(obj_log_buf, "DATASEC license"), "obj_log_not_empty");
+ ASSERT_OK_PTR(strstr(good_log_buf, "0: R1=ctx(id=0,off=0,imm=0) R10=fp0"),
+ "good_log_verbose");
+ ASSERT_OK_PTR(strstr(bad_log_buf, "invalid access to map value, value_size=16 off=16000 size=4"),
+ "bad_log_not_empty");
+
+ if (env.verbosity > VERBOSE_NONE) {
+ printf("LIBBPF LOG: \n=================\n%s=================\n", libbpf_log_buf);
+ printf("OBJ LOG: \n=================\n%s=================\n", obj_log_buf);
+ printf("GOOD_PROG LOG:\n=================\n%s=================\n", good_log_buf);
+ printf("BAD_PROG LOG:\n=================\n%s=================\n", bad_log_buf);
+ }
+
+ /* reset everything */
+ test_log_buf__destroy(skel);
+ obj_log_buf[0] = good_log_buf[0] = bad_log_buf[0] = '\0';
+ libbpf_log_buf[0] = '\0';
+ libbpf_log_pos = 0;
+ libbpf_log_error = false;
+
+ /* In the second round we let bad_prog's failure be logged through print callback */
+ opts.kernel_log_buf = NULL; /* let everything through into print callback */
+ opts.kernel_log_size = 0;
+ opts.kernel_log_level = 1;
+
+ skel = test_log_buf__open_opts(&opts);
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ goto cleanup;
+
+ /* set normal verbose level for good_prog to check log_level is taken into account */
+ bpf_program__set_log_buf(skel->progs.good_prog, good_log_buf, log_buf_sz);
+ bpf_program__set_log_level(skel->progs.good_prog, 1);
+
+ err = test_log_buf__load(skel);
+ if (!ASSERT_ERR(err, "unexpected_load_success"))
+ goto cleanup;
+
+ ASSERT_FALSE(libbpf_log_error, "libbpf_log_error");
+
+ /* this time prog loading error should be logged through print callback */
+ ASSERT_OK_PTR(strstr(libbpf_log_buf, "libbpf: prog 'bad_prog': -- BEGIN PROG LOAD LOG --"),
+ "libbpf_log_correct");
+ ASSERT_STREQ(obj_log_buf, "", "obj_log__empty");
+ ASSERT_STREQ(good_log_buf, "processed 4 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0\n",
+ "good_log_ok");
+ ASSERT_STREQ(bad_log_buf, "", "bad_log_empty");
+
+ if (env.verbosity > VERBOSE_NONE) {
+ printf("LIBBPF LOG: \n=================\n%s=================\n", libbpf_log_buf);
+ printf("OBJ LOG: \n=================\n%s=================\n", obj_log_buf);
+ printf("GOOD_PROG LOG:\n=================\n%s=================\n", good_log_buf);
+ printf("BAD_PROG LOG:\n=================\n%s=================\n", bad_log_buf);
+ }
+
+cleanup:
+ free(obj_log_buf);
+ test_log_buf__destroy(skel);
+ libbpf_set_print(old_print_cb);
+}
+
+static void bpf_prog_load_log_buf(void)
+{
+ const struct bpf_insn good_prog_insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ const size_t good_prog_insn_cnt = sizeof(good_prog_insns) / sizeof(struct bpf_insn);
+ const struct bpf_insn bad_prog_insns[] = {
+ BPF_EXIT_INSN(),
+ };
+ size_t bad_prog_insn_cnt = sizeof(bad_prog_insns) / sizeof(struct bpf_insn);
+ LIBBPF_OPTS(bpf_prog_load_opts, opts);
+ const size_t log_buf_sz = 1024 * 1024;
+ char *log_buf;
+ int fd = -1;
+
+ log_buf = malloc(log_buf_sz);
+ if (!ASSERT_OK_PTR(log_buf, "log_buf_alloc"))
+ return;
+ opts.log_buf = log_buf;
+ opts.log_size = log_buf_sz;
+
+ /* with log_level == 0 log_buf shoud stay empty for good prog */
+ log_buf[0] = '\0';
+ opts.log_level = 0;
+ fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "good_prog", "GPL",
+ good_prog_insns, good_prog_insn_cnt, &opts);
+ ASSERT_STREQ(log_buf, "", "good_log_0");
+ ASSERT_GE(fd, 0, "good_fd1");
+ if (fd >= 0)
+ close(fd);
+ fd = -1;
+
+ /* log_level == 2 should always fill log_buf, even for good prog */
+ log_buf[0] = '\0';
+ opts.log_level = 2;
+ fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "good_prog", "GPL",
+ good_prog_insns, good_prog_insn_cnt, &opts);
+ ASSERT_OK_PTR(strstr(log_buf, "0: R1=ctx(id=0,off=0,imm=0) R10=fp0"), "good_log_2");
+ ASSERT_GE(fd, 0, "good_fd2");
+ if (fd >= 0)
+ close(fd);
+ fd = -1;
+
+ /* log_level == 0 should fill log_buf for bad prog */
+ log_buf[0] = '\0';
+ opts.log_level = 0;
+ fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "bad_prog", "GPL",
+ bad_prog_insns, bad_prog_insn_cnt, &opts);
+ ASSERT_OK_PTR(strstr(log_buf, "R0 !read_ok"), "bad_log_0");
+ ASSERT_LT(fd, 0, "bad_fd");
+ if (fd >= 0)
+ close(fd);
+ fd = -1;
+
+ free(log_buf);
+}
+
+static void bpf_btf_load_log_buf(void)
+{
+ LIBBPF_OPTS(bpf_btf_load_opts, opts);
+ const size_t log_buf_sz = 1024 * 1024;
+ const void *raw_btf_data;
+ __u32 raw_btf_size;
+ struct btf *btf;
+ char *log_buf;
+ int fd = -1;
+
+ btf = btf__new_empty();
+ if (!ASSERT_OK_PTR(btf, "empty_btf"))
+ return;
+
+ ASSERT_GT(btf__add_int(btf, "int", 4, 0), 0, "int_type");
+
+ raw_btf_data = btf__raw_data(btf, &raw_btf_size);
+ if (!ASSERT_OK_PTR(raw_btf_data, "raw_btf_data_good"))
+ goto cleanup;
+
+ log_buf = malloc(log_buf_sz);
+ if (!ASSERT_OK_PTR(log_buf, "log_buf_alloc"))
+ goto cleanup;
+ opts.log_buf = log_buf;
+ opts.log_size = log_buf_sz;
+
+ /* with log_level == 0 log_buf shoud stay empty for good BTF */
+ log_buf[0] = '\0';
+ opts.log_level = 0;
+ fd = bpf_btf_load(raw_btf_data, raw_btf_size, &opts);
+ ASSERT_STREQ(log_buf, "", "good_log_0");
+ ASSERT_GE(fd, 0, "good_fd1");
+ if (fd >= 0)
+ close(fd);
+ fd = -1;
+
+ /* log_level == 2 should always fill log_buf, even for good BTF */
+ log_buf[0] = '\0';
+ opts.log_level = 2;
+ fd = bpf_btf_load(raw_btf_data, raw_btf_size, &opts);
+ printf("LOG_BUF: %s\n", log_buf);
+ ASSERT_OK_PTR(strstr(log_buf, "magic: 0xeb9f"), "good_log_2");
+ ASSERT_GE(fd, 0, "good_fd2");
+ if (fd >= 0)
+ close(fd);
+ fd = -1;
+
+ /* make BTF bad, add pointer pointing to non-existing type */
+ ASSERT_GT(btf__add_ptr(btf, 100), 0, "bad_ptr_type");
+
+ raw_btf_data = btf__raw_data(btf, &raw_btf_size);
+ if (!ASSERT_OK_PTR(raw_btf_data, "raw_btf_data_bad"))
+ goto cleanup;
+
+ /* log_level == 0 should fill log_buf for bad BTF */
+ log_buf[0] = '\0';
+ opts.log_level = 0;
+ fd = bpf_btf_load(raw_btf_data, raw_btf_size, &opts);
+ printf("LOG_BUF: %s\n", log_buf);
+ ASSERT_OK_PTR(strstr(log_buf, "[2] PTR (anon) type_id=100 Invalid type_id"), "bad_log_0");
+ ASSERT_LT(fd, 0, "bad_fd");
+ if (fd >= 0)
+ close(fd);
+ fd = -1;
+
+cleanup:
+ free(log_buf);
+ btf__free(btf);
+}
+
+void test_log_buf(void)
+{
+ if (test__start_subtest("obj_load_log_buf"))
+ obj_load_log_buf();
+ if (test__start_subtest("bpf_prog_load_log_buf"))
+ bpf_prog_load_log_buf();
+ if (test__start_subtest("bpf_btf_load_log_buf"))
+ bpf_btf_load_log_buf();
+}
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_log_buf.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+int a[4];
+const volatile int off = 4000;
+
+SEC("raw_tp/sys_enter")
+int good_prog(const void *ctx)
+{
+ a[0] = (int)(long)ctx;
+ return a[1];
+}
+
+SEC("raw_tp/sys_enter")
+int bad_prog(const void *ctx)
+{
+ /* out of bounds access */
+ return a[off];
+}
+
+char _license[] SEC("license") = "GPL";