[PATCH 7/7] selftests/bpf: copy_from_user_dynptr test
From: Levi Zim via B4 Relay <devnull+rsworktech.outlook.com@kernel.org>
Date: 2025-01-25 08:24:16
Also in:
b4-sent, bpf, linux-kselftest, lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Shuah Khan, Linus Torvalds
From: Levi Zim <redacted> This patch adds a test for copy_from_user_dynptr helper, which tests reading variable length of user memory into a ringbuf backed dynptr. Signed-off-by: Levi Zim <redacted> --- tools/testing/selftests/bpf/prog_tests/dynptr.c | 3 ++ tools/testing/selftests/bpf/progs/dynptr_success.c | 34 ++++++++++++++++++++++ 2 files changed, 37 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c
index a5a61a4c570d803bfca2af3f1a3b7d5eb0b8197f..a0095204609c710d49a6105ebf8be44723fb53d2 100644
--- a/tools/testing/selftests/bpf/prog_tests/dynptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c@@ -33,6 +33,7 @@ static struct { {"test_dynptr_skb_tp_btf", SETUP_SKB_PROG_TP}, {"test_probe_read_kernel_dynptr", SETUP_RINGBUF}, {"test_probe_read_user_dynptr", SETUP_RINGBUF}, + {"test_copy_from_user_dynptr", SETUP_RINGBUF}, }; static int ringbuf_cb(void *ctx, void *data, size_t len)
@@ -43,6 +44,8 @@ static int ringbuf_cb(void *ctx, void *data, size_t len) if (!ASSERT_EQ(len, skel->data->test_buf.length, "length")) return -E2BIG; + ASSERT_EQ(skel->bss->err, 0, "err"); + if (!ASSERT_MEMEQ(buf, skel->data->test_buf.buf, len, "ringbuf_cb")) return -EINVAL;
diff --git a/tools/testing/selftests/bpf/progs/dynptr_success.c b/tools/testing/selftests/bpf/progs/dynptr_success.c
index 5317860290dccb0862b6a0b94bb6f738c8d92835..10dda58fed66a05ad1b08c8684784fddabe3f4ad 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_success.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_success.c@@ -639,3 +639,37 @@ int test_probe_read_user_dynptr(void *ctx) bpf_ringbuf_submit_dynptr(&ptr, 0); return 0; } + +SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep") +int test_copy_from_user_dynptr(void *ctx) +{ + struct bpf_dynptr ptr; + int copy_len; + + if (bpf_get_current_pid_tgid() >> 32 != pid) + return 0; + + err = bpf_probe_read_user(©_len, sizeof(copy_len), &user_ptr->length); + if (err < 0 || copy_len < 0) { + err = 1; + return 0; + } + + if (copy_len > MAX_BUFFER_LEN) + copy_len = MAX_BUFFER_LEN; + + bpf_ringbuf_reserve_dynptr(&ringbuf, copy_len, 0, &ptr); + + if (-E2BIG != bpf_copy_from_user_dynptr(&ptr, 0, MAX_BUFFER_LEN + 1, + &user_ptr->buf, 0)) { + err = 2; + goto cleanup; + } + + err = bpf_copy_from_user_dynptr(&ptr, 0, copy_len, + &user_ptr->buf, 0); + +cleanup: + bpf_ringbuf_submit_dynptr(&ptr, 0); + return 0; +}
--
2.48.1