From: Levi Zim rsworktech@outlook.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@outlook.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; +}