From 58d84bee58465cc9f6a63ca3931240419497f917 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Sun, 20 Nov 2022 11:54:42 -0800 Subject: [PATCH] bpf: Add type cast unit tests Three tests are added. One is from John Fastabend ({1]) which tests tracing style access for xdp program from the kernel ctx. Another is a tc test to test both kernel ctx tracing style access and explicit non-ctx type cast. The third one is for negative tests including two tests, a tp_bpf test where the bpf_rdonly_cast() returns a untrusted ptr which cannot be used as helper argument, and a tracepoint test where the kernel ctx is a u64. Also added the test to DENYLIST.s390x since s390 does not currently support calling kernel functions in JIT mode. [1] https://lore.kernel.org/bpf/20221109215242.1279993-1-john.fastabend@gmail.com/ Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20221120195442.3114844-1-yhs@fb.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/DENYLIST.s390x | 1 + tools/testing/selftests/bpf/prog_tests/type_cast.c | 114 +++++++++++++++++++++ tools/testing/selftests/bpf/progs/type_cast.c | 83 +++++++++++++++ 3 files changed, 198 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/type_cast.c create mode 100644 tools/testing/selftests/bpf/progs/type_cast.c diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x index f70a677..12cf215 100644 --- a/tools/testing/selftests/bpf/DENYLIST.s390x +++ b/tools/testing/selftests/bpf/DENYLIST.s390x @@ -71,6 +71,7 @@ trace_printk # trace_printk__load unexpected error: trace_vprintk # trace_vprintk__open_and_load unexpected error: -9 (?) tracing_struct # failed to auto-attach: -524 (trampoline) trampoline_count # prog 'prog1': failed to attach: ERROR: strerror_r(-524)=22 (trampoline) +type_cast # JIT does not support calling kernel function unpriv_bpf_disabled # fentry user_ringbuf # failed to find kernel BTF type ID of '__s390x_sys_prctl': -3 (?) verif_stats # trace_vprintk__open_and_load unexpected error: -9 (?) diff --git a/tools/testing/selftests/bpf/prog_tests/type_cast.c b/tools/testing/selftests/bpf/prog_tests/type_cast.c new file mode 100644 index 0000000..9317d5fa --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/type_cast.c @@ -0,0 +1,114 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ +#include +#include +#include "type_cast.skel.h" + +static void test_xdp(void) +{ + struct type_cast *skel; + int err, prog_fd; + char buf[128]; + + LIBBPF_OPTS(bpf_test_run_opts, topts, + .data_in = &pkt_v4, + .data_size_in = sizeof(pkt_v4), + .data_out = buf, + .data_size_out = sizeof(buf), + .repeat = 1, + ); + + skel = type_cast__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + bpf_program__set_autoload(skel->progs.md_xdp, true); + err = type_cast__load(skel); + if (!ASSERT_OK(err, "skel_load")) + goto out; + + prog_fd = bpf_program__fd(skel->progs.md_xdp); + err = bpf_prog_test_run_opts(prog_fd, &topts); + ASSERT_OK(err, "test_run"); + ASSERT_EQ(topts.retval, XDP_PASS, "xdp test_run retval"); + + ASSERT_EQ(skel->bss->ifindex, 1, "xdp_md ifindex"); + ASSERT_EQ(skel->bss->ifindex, skel->bss->ingress_ifindex, "xdp_md ingress_ifindex"); + ASSERT_STREQ(skel->bss->name, "lo", "xdp_md name"); + ASSERT_NEQ(skel->bss->inum, 0, "xdp_md inum"); + +out: + type_cast__destroy(skel); +} + +static void test_tc(void) +{ + struct type_cast *skel; + int err, prog_fd; + + LIBBPF_OPTS(bpf_test_run_opts, topts, + .data_in = &pkt_v4, + .data_size_in = sizeof(pkt_v4), + .repeat = 1, + ); + + skel = type_cast__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + bpf_program__set_autoload(skel->progs.md_skb, true); + err = type_cast__load(skel); + if (!ASSERT_OK(err, "skel_load")) + goto out; + + prog_fd = bpf_program__fd(skel->progs.md_skb); + err = bpf_prog_test_run_opts(prog_fd, &topts); + ASSERT_OK(err, "test_run"); + ASSERT_EQ(topts.retval, 0, "tc test_run retval"); + + ASSERT_EQ(skel->bss->meta_len, 0, "skb meta_len"); + ASSERT_EQ(skel->bss->frag0_len, 0, "skb frag0_len"); + ASSERT_NEQ(skel->bss->kskb_len, 0, "skb len"); + ASSERT_NEQ(skel->bss->kskb2_len, 0, "skb2 len"); + ASSERT_EQ(skel->bss->kskb_len, skel->bss->kskb2_len, "skb len compare"); + +out: + type_cast__destroy(skel); +} + +static const char * const negative_tests[] = { + "untrusted_ptr", + "kctx_u64", +}; + +static void test_negative(void) +{ + struct bpf_program *prog; + struct type_cast *skel; + int i, err; + + for (i = 0; i < ARRAY_SIZE(negative_tests); i++) { + skel = type_cast__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + prog = bpf_object__find_program_by_name(skel->obj, negative_tests[i]); + if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name")) + goto out; + bpf_program__set_autoload(prog, true); + err = type_cast__load(skel); + ASSERT_ERR(err, "skel_load"); +out: + type_cast__destroy(skel); + } +} + +void test_type_cast(void) +{ + if (test__start_subtest("xdp")) + test_xdp(); + if (test__start_subtest("tc")) + test_tc(); + if (test__start_subtest("negative")) + test_negative(); +} diff --git a/tools/testing/selftests/bpf/progs/type_cast.c b/tools/testing/selftests/bpf/progs/type_cast.c new file mode 100644 index 0000000..eb78e6f --- /dev/null +++ b/tools/testing/selftests/bpf/progs/type_cast.c @@ -0,0 +1,83 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ +#include "vmlinux.h" +#include +#include +#include + +struct { + __uint(type, BPF_MAP_TYPE_TASK_STORAGE); + __uint(map_flags, BPF_F_NO_PREALLOC); + __type(key, int); + __type(value, long); +} enter_id SEC(".maps"); + +#define IFNAMSIZ 16 + +int ifindex, ingress_ifindex; +char name[IFNAMSIZ]; +unsigned int inum; +unsigned int meta_len, frag0_len, kskb_len, kskb2_len; + +void *bpf_cast_to_kern_ctx(void *) __ksym; +void *bpf_rdonly_cast(void *, __u32) __ksym; + +SEC("?xdp") +int md_xdp(struct xdp_md *ctx) +{ + struct xdp_buff *kctx = bpf_cast_to_kern_ctx(ctx); + struct net_device *dev; + + dev = kctx->rxq->dev; + ifindex = dev->ifindex; + inum = dev->nd_net.net->ns.inum; + __builtin_memcpy(name, dev->name, IFNAMSIZ); + ingress_ifindex = ctx->ingress_ifindex; + return XDP_PASS; +} + +SEC("?tc") +int md_skb(struct __sk_buff *skb) +{ + struct sk_buff *kskb = bpf_cast_to_kern_ctx(skb); + struct skb_shared_info *shared_info; + struct sk_buff *kskb2; + + kskb_len = kskb->len; + + /* Simulate the following kernel macro: + * #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB))) + */ + shared_info = bpf_rdonly_cast(kskb->head + kskb->end, + bpf_core_type_id_kernel(struct skb_shared_info)); + meta_len = shared_info->meta_len; + frag0_len = shared_info->frag_list->len; + + /* kskb2 should be equal to kskb */ + kskb2 = bpf_rdonly_cast(kskb, bpf_core_type_id_kernel(struct sk_buff)); + kskb2_len = kskb2->len; + return 0; +} + +SEC("?tp_btf/sys_enter") +int BPF_PROG(untrusted_ptr, struct pt_regs *regs, long id) +{ + struct task_struct *task, *task_dup; + long *ptr; + + task = bpf_get_current_task_btf(); + task_dup = bpf_rdonly_cast(task, bpf_core_type_id_kernel(struct task_struct)); + (void)bpf_task_storage_get(&enter_id, task_dup, 0, 0); + return 0; +} + +SEC("?tracepoint/syscalls/sys_enter_nanosleep") +int kctx_u64(void *ctx) +{ + u64 *kctx = bpf_rdonly_cast(ctx, bpf_core_type_id_kernel(u64)); + + (void)kctx; + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.7.4