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Message-Id: <20250125-bpf_dynptr_probe-v2-5-c42c87f97afe@outlook.com>
Date: Sat, 25 Jan 2025 16:29:52 +0800
From: Levi Zim via B4 Relay <devnull+rsworktech.outlook.com@...nel.org>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>,
Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>,
Yonghong Song <yonghong.song@...ux.dev>,
John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>,
Jiri Olsa <jolsa@...nel.org>, Matt Bobrowski <mattbobrowski@...gle.com>,
Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
Andrii Nakryiko <andrii.nakryiko@...il.com>,
Levi Zim <rsworktech@...look.com>
Subject: [PATCH bpf-next v2 5/7] selftests/bpf: probe_read_kernel_dynptr
test
From: Levi Zim <rsworktech@...look.com>
This patch adds a test for probe_read_kernel_dynptr helper,
which tests reading variable length of kernel memory into a ringbuf
backed dynptr.
Signed-off-by: Levi Zim <rsworktech@...look.com>
---
tools/testing/selftests/bpf/prog_tests/dynptr.c | 40 +++++++++++++++++++++-
tools/testing/selftests/bpf/progs/dynptr_success.c | 38 ++++++++++++++++++++
2 files changed, 77 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c
index b614a5272dfd6486e287181270a0bcf63f638344..d9a25c2873b6ed4219e063845b1caf978a7016fd 100644
--- a/tools/testing/selftests/bpf/prog_tests/dynptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c
@@ -10,6 +10,7 @@ enum test_setup_type {
SETUP_SYSCALL_SLEEP,
SETUP_SKB_PROG,
SETUP_SKB_PROG_TP,
+ SETUP_RINGBUF,
};
static struct {
@@ -30,20 +31,37 @@ static struct {
{"test_dynptr_skb_no_buff", SETUP_SKB_PROG},
{"test_dynptr_skb_strcmp", SETUP_SKB_PROG},
{"test_dynptr_skb_tp_btf", SETUP_SKB_PROG_TP},
+ {"test_probe_read_kernel_dynptr", SETUP_RINGBUF},
};
+static int ringbuf_cb(void *ctx, void *data, size_t len)
+{
+ struct dynptr_success *skel = ctx;
+ const char *buf = data;
+
+ if (!ASSERT_EQ(len, skel->data->test_buf.length, "length"))
+ return -E2BIG;
+
+ if (!ASSERT_MEMEQ(buf, skel->data->test_buf.buf, len, "ringbuf_cb"))
+ return -EINVAL;
+
+ return 0;
+}
+
static void verify_success(const char *prog_name, enum test_setup_type setup_type)
{
+ struct ring_buffer *rb = NULL;
struct dynptr_success *skel;
struct bpf_program *prog;
struct bpf_link *link;
- int err;
+ int err, ret;
skel = dynptr_success__open();
if (!ASSERT_OK_PTR(skel, "dynptr_success__open"))
return;
skel->bss->pid = getpid();
+ skel->data->test_buf.length = 8;
prog = bpf_object__find_program_by_name(skel->obj, prog_name);
if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
@@ -63,6 +81,24 @@ static void verify_success(const char *prog_name, enum test_setup_type setup_typ
usleep(1);
+ bpf_link__destroy(link);
+ break;
+ case SETUP_RINGBUF:
+ link = bpf_program__attach(prog);
+ if (!ASSERT_OK_PTR(link, "bpf_program__attach"))
+ goto cleanup;
+
+ rb = ring_buffer__new(bpf_map__fd(skel->maps.ringbuf), ringbuf_cb, skel, NULL);
+ if (!ASSERT_OK_PTR(rb, "ring_buffer__new"))
+ goto cleanup;
+
+ usleep(1);
+
+ ret = ring_buffer__poll(rb, 5000);
+
+ if (!ASSERT_EQ(ret, 1, "ring_buffer__poll"))
+ goto cleanup;
+
bpf_link__destroy(link);
break;
case SETUP_SKB_PROG:
@@ -125,6 +161,8 @@ static void verify_success(const char *prog_name, enum test_setup_type setup_typ
ASSERT_EQ(skel->bss->err, 0, "err");
cleanup:
+ if (rb != NULL)
+ ring_buffer__free(rb);
dynptr_success__destroy(skel);
}
diff --git a/tools/testing/selftests/bpf/progs/dynptr_success.c b/tools/testing/selftests/bpf/progs/dynptr_success.c
index bfcc85686cf046361b451f97f4cd310a6ccdb1ed..64c698f83a37bfe924db93d36982a0a1c8defe62 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_success.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_success.c
@@ -567,3 +567,41 @@ int BPF_PROG(test_dynptr_skb_tp_btf, void *skb, void *location)
return 1;
}
+
+#define MAX_BUFFER_LEN 20
+
+struct {
+ __u32 length;
+ char buf[MAX_BUFFER_LEN];
+} test_buf = {
+ .length = 0,
+ .buf = "0123456789abcdef",
+};
+
+SEC("?tp/syscalls/sys_enter_nanosleep")
+int test_probe_read_kernel_dynptr(void *ctx)
+{
+ int copy_len = test_buf.length;
+ struct bpf_dynptr ptr;
+
+ if (bpf_get_current_pid_tgid() >> 32 != pid)
+ return 0;
+
+ if (test_buf.length > MAX_BUFFER_LEN)
+ copy_len = MAX_BUFFER_LEN;
+
+ bpf_ringbuf_reserve_dynptr(&ringbuf, copy_len, 0, &ptr);
+
+ if (-E2BIG != bpf_probe_read_kernel_dynptr(&ptr, 0, MAX_BUFFER_LEN + 1,
+ test_buf.buf, 0)) {
+ err = 1;
+ goto cleanup;
+ }
+
+ err = bpf_probe_read_kernel_dynptr(&ptr, 0, copy_len,
+ test_buf.buf, 0);
+
+cleanup:
+ bpf_ringbuf_submit_dynptr(&ptr, 0);
+ return 0;
+}
--
2.48.1
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