From 888d83b961f6057aa377065b60c5206fd8bff97c Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Wed, 7 Oct 2020 17:10:24 -0700 Subject: [PATCH] selftests/bpf: Validate libbpf's auto-sizing of LD/ST/STX instructions Add selftests validating libbpf's auto-resizing of load/store instructions when used with CO-RE relocations. An explicit and manual approach with using bpf_core_read() is also demonstrated and tested. Separate BPF program is supposed to fail due to using signed integers of sizes that differ from kernel's sizes. To reliably simulate 32-bit BTF (i.e., the one with sizeof(long) == sizeof(void *) == 4), selftest generates its own custom BTF and passes it as a replacement for real kernel BTF. This allows to test 32/64-bitness mix on all architectures. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201008001025.292064-5-andrii@kernel.org --- .../selftests/bpf/prog_tests/core_autosize.c | 225 ++++++++++++++++++ .../selftests/bpf/progs/test_core_autosize.c | 172 +++++++++++++ 2 files changed, 397 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/core_autosize.c create mode 100644 tools/testing/selftests/bpf/progs/test_core_autosize.c diff --git a/tools/testing/selftests/bpf/prog_tests/core_autosize.c b/tools/testing/selftests/bpf/prog_tests/core_autosize.c new file mode 100644 index 000000000000..981c251453d9 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/core_autosize.c @@ -0,0 +1,225 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Facebook */ + +#include +#include + +/* real layout and sizes according to test's (32-bit) BTF + * needs to be defined before skeleton is included */ +struct test_struct___real { + unsigned int ptr; /* can't use `void *`, it is always 8 byte in BPF target */ + unsigned int val2; + unsigned long long val1; + unsigned short val3; + unsigned char val4; + unsigned char _pad; +}; + +#include "test_core_autosize.skel.h" + +static int duration = 0; + +static struct { + unsigned long long ptr_samesized; + unsigned long long val1_samesized; + unsigned long long val2_samesized; + unsigned long long val3_samesized; + unsigned long long val4_samesized; + struct test_struct___real output_samesized; + + unsigned long long ptr_downsized; + unsigned long long val1_downsized; + unsigned long long val2_downsized; + unsigned long long val3_downsized; + unsigned long long val4_downsized; + struct test_struct___real output_downsized; + + unsigned long long ptr_probed; + unsigned long long val1_probed; + unsigned long long val2_probed; + unsigned long long val3_probed; + unsigned long long val4_probed; + + unsigned long long ptr_signed; + unsigned long long val1_signed; + unsigned long long val2_signed; + unsigned long long val3_signed; + unsigned long long val4_signed; + struct test_struct___real output_signed; +} out; + +void test_core_autosize(void) +{ + char btf_file[] = "/tmp/core_autosize.btf.XXXXXX"; + int err, fd = -1, zero = 0; + int char_id, short_id, int_id, long_long_id, void_ptr_id, id; + struct test_core_autosize* skel = NULL; + struct bpf_object_load_attr load_attr = {}; + struct bpf_program *prog; + struct bpf_map *bss_map; + struct btf *btf = NULL; + size_t written; + const void *raw_data; + __u32 raw_sz; + FILE *f = NULL; + + btf = btf__new_empty(); + if (!ASSERT_OK_PTR(btf, "empty_btf")) + return; + /* Emit the following struct with 32-bit pointer size: + * + * struct test_struct { + * void *ptr; + * unsigned long val2; + * unsigned long long val1; + * unsigned short val3; + * unsigned char val4; + * char: 8; + * }; + * + * This struct is going to be used as the "kernel BTF" for this test. + * It's equivalent memory-layout-wise to test_struct__real above. + */ + + /* force 32-bit pointer size */ + btf__set_pointer_size(btf, 4); + + char_id = btf__add_int(btf, "unsigned char", 1, 0); + ASSERT_EQ(char_id, 1, "char_id"); + short_id = btf__add_int(btf, "unsigned short", 2, 0); + ASSERT_EQ(short_id, 2, "short_id"); + /* "long unsigned int" of 4 byte size tells BTF that sizeof(void *) == 4 */ + int_id = btf__add_int(btf, "long unsigned int", 4, 0); + ASSERT_EQ(int_id, 3, "int_id"); + long_long_id = btf__add_int(btf, "unsigned long long", 8, 0); + ASSERT_EQ(long_long_id, 4, "long_long_id"); + void_ptr_id = btf__add_ptr(btf, 0); + ASSERT_EQ(void_ptr_id, 5, "void_ptr_id"); + + id = btf__add_struct(btf, "test_struct", 20 /* bytes */); + ASSERT_EQ(id, 6, "struct_id"); + err = btf__add_field(btf, "ptr", void_ptr_id, 0, 0); + err = err ?: btf__add_field(btf, "val2", int_id, 32, 0); + err = err ?: btf__add_field(btf, "val1", long_long_id, 64, 0); + err = err ?: btf__add_field(btf, "val3", short_id, 128, 0); + err = err ?: btf__add_field(btf, "val4", char_id, 144, 0); + ASSERT_OK(err, "struct_fields"); + + fd = mkstemp(btf_file); + if (CHECK(fd < 0, "btf_tmp", "failed to create file: %d\n", fd)) + goto cleanup; + f = fdopen(fd, "w"); + if (!ASSERT_OK_PTR(f, "btf_fdopen")) + goto cleanup; + + raw_data = btf__get_raw_data(btf, &raw_sz); + if (!ASSERT_OK_PTR(raw_data, "raw_data")) + goto cleanup; + written = fwrite(raw_data, 1, raw_sz, f); + if (CHECK(written != raw_sz, "btf_write", "written: %zu, errno: %d\n", written, errno)) + goto cleanup; + fflush(f); + fclose(f); + f = NULL; + close(fd); + fd = -1; + + /* open and load BPF program with custom BTF as the kernel BTF */ + skel = test_core_autosize__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + /* disable handle_signed() for now */ + prog = bpf_object__find_program_by_name(skel->obj, "handle_signed"); + if (!ASSERT_OK_PTR(prog, "prog_find")) + goto cleanup; + bpf_program__set_autoload(prog, false); + + load_attr.obj = skel->obj; + load_attr.target_btf_path = btf_file; + err = bpf_object__load_xattr(&load_attr); + if (!ASSERT_OK(err, "prog_load")) + goto cleanup; + + prog = bpf_object__find_program_by_name(skel->obj, "handle_samesize"); + if (!ASSERT_OK_PTR(prog, "prog_find")) + goto cleanup; + skel->links.handle_samesize = bpf_program__attach(prog); + if (!ASSERT_OK_PTR(skel->links.handle_samesize, "prog_attach")) + goto cleanup; + + prog = bpf_object__find_program_by_name(skel->obj, "handle_downsize"); + if (!ASSERT_OK_PTR(prog, "prog_find")) + goto cleanup; + skel->links.handle_downsize = bpf_program__attach(prog); + if (!ASSERT_OK_PTR(skel->links.handle_downsize, "prog_attach")) + goto cleanup; + + prog = bpf_object__find_program_by_name(skel->obj, "handle_probed"); + if (!ASSERT_OK_PTR(prog, "prog_find")) + goto cleanup; + skel->links.handle_probed = bpf_program__attach(prog); + if (!ASSERT_OK_PTR(skel->links.handle_probed, "prog_attach")) + goto cleanup; + + usleep(1); + + bss_map = bpf_object__find_map_by_name(skel->obj, "test_cor.bss"); + if (!ASSERT_OK_PTR(bss_map, "bss_map_find")) + goto cleanup; + + err = bpf_map_lookup_elem(bpf_map__fd(bss_map), &zero, (void *)&out); + if (!ASSERT_OK(err, "bss_lookup")) + goto cleanup; + + ASSERT_EQ(out.ptr_samesized, 0x01020304, "ptr_samesized"); + ASSERT_EQ(out.val1_samesized, 0x1020304050607080, "val1_samesized"); + ASSERT_EQ(out.val2_samesized, 0x0a0b0c0d, "val2_samesized"); + ASSERT_EQ(out.val3_samesized, 0xfeed, "val3_samesized"); + ASSERT_EQ(out.val4_samesized, 0xb9, "val4_samesized"); + ASSERT_EQ(out.output_samesized.ptr, 0x01020304, "ptr_samesized"); + ASSERT_EQ(out.output_samesized.val1, 0x1020304050607080, "val1_samesized"); + ASSERT_EQ(out.output_samesized.val2, 0x0a0b0c0d, "val2_samesized"); + ASSERT_EQ(out.output_samesized.val3, 0xfeed, "val3_samesized"); + ASSERT_EQ(out.output_samesized.val4, 0xb9, "val4_samesized"); + + ASSERT_EQ(out.ptr_downsized, 0x01020304, "ptr_downsized"); + ASSERT_EQ(out.val1_downsized, 0x1020304050607080, "val1_downsized"); + ASSERT_EQ(out.val2_downsized, 0x0a0b0c0d, "val2_downsized"); + ASSERT_EQ(out.val3_downsized, 0xfeed, "val3_downsized"); + ASSERT_EQ(out.val4_downsized, 0xb9, "val4_downsized"); + ASSERT_EQ(out.output_downsized.ptr, 0x01020304, "ptr_downsized"); + ASSERT_EQ(out.output_downsized.val1, 0x1020304050607080, "val1_downsized"); + ASSERT_EQ(out.output_downsized.val2, 0x0a0b0c0d, "val2_downsized"); + ASSERT_EQ(out.output_downsized.val3, 0xfeed, "val3_downsized"); + ASSERT_EQ(out.output_downsized.val4, 0xb9, "val4_downsized"); + + ASSERT_EQ(out.ptr_probed, 0x01020304, "ptr_probed"); + ASSERT_EQ(out.val1_probed, 0x1020304050607080, "val1_probed"); + ASSERT_EQ(out.val2_probed, 0x0a0b0c0d, "val2_probed"); + ASSERT_EQ(out.val3_probed, 0xfeed, "val3_probed"); + ASSERT_EQ(out.val4_probed, 0xb9, "val4_probed"); + + test_core_autosize__destroy(skel); + skel = NULL; + + /* now re-load with handle_signed() enabled, it should fail loading */ + skel = test_core_autosize__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + load_attr.obj = skel->obj; + load_attr.target_btf_path = btf_file; + err = bpf_object__load_xattr(&load_attr); + if (!ASSERT_ERR(err, "bad_prog_load")) + goto cleanup; + +cleanup: + if (f) + fclose(f); + if (fd >= 0) + close(fd); + remove(btf_file); + btf__free(btf); + test_core_autosize__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_core_autosize.c b/tools/testing/selftests/bpf/progs/test_core_autosize.c new file mode 100644 index 000000000000..44f5aa2e8956 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_core_autosize.c @@ -0,0 +1,172 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Facebook */ + +#include +#include +#include +#include + +char _license[] SEC("license") = "GPL"; + +/* fields of exactly the same size */ +struct test_struct___samesize { + void *ptr; + unsigned long long val1; + unsigned int val2; + unsigned short val3; + unsigned char val4; +} __attribute((preserve_access_index)); + +/* unsigned fields that have to be downsized by libbpf */ +struct test_struct___downsize { + void *ptr; + unsigned long val1; + unsigned long val2; + unsigned long val3; + unsigned long val4; + /* total sz: 40 */ +} __attribute__((preserve_access_index)); + +/* fields with signed integers of wrong size, should be rejected */ +struct test_struct___signed { + void *ptr; + long val1; + long val2; + long val3; + long val4; +} __attribute((preserve_access_index)); + +/* real layout and sizes according to test's (32-bit) BTF */ +struct test_struct___real { + unsigned int ptr; /* can't use `void *`, it is always 8 byte in BPF target */ + unsigned int val2; + unsigned long long val1; + unsigned short val3; + unsigned char val4; + unsigned char _pad; + /* total sz: 20 */ +}; + +struct test_struct___real input = { + .ptr = 0x01020304, + .val1 = 0x1020304050607080, + .val2 = 0x0a0b0c0d, + .val3 = 0xfeed, + .val4 = 0xb9, + ._pad = 0xff, /* make sure no accidental zeros are present */ +}; + +unsigned long long ptr_samesized = 0; +unsigned long long val1_samesized = 0; +unsigned long long val2_samesized = 0; +unsigned long long val3_samesized = 0; +unsigned long long val4_samesized = 0; +struct test_struct___real output_samesized = {}; + +unsigned long long ptr_downsized = 0; +unsigned long long val1_downsized = 0; +unsigned long long val2_downsized = 0; +unsigned long long val3_downsized = 0; +unsigned long long val4_downsized = 0; +struct test_struct___real output_downsized = {}; + +unsigned long long ptr_probed = 0; +unsigned long long val1_probed = 0; +unsigned long long val2_probed = 0; +unsigned long long val3_probed = 0; +unsigned long long val4_probed = 0; + +unsigned long long ptr_signed = 0; +unsigned long long val1_signed = 0; +unsigned long long val2_signed = 0; +unsigned long long val3_signed = 0; +unsigned long long val4_signed = 0; +struct test_struct___real output_signed = {}; + +SEC("raw_tp/sys_exit") +int handle_samesize(void *ctx) +{ + struct test_struct___samesize *in = (void *)&input; + struct test_struct___samesize *out = (void *)&output_samesized; + + ptr_samesized = (unsigned long long)in->ptr; + val1_samesized = in->val1; + val2_samesized = in->val2; + val3_samesized = in->val3; + val4_samesized = in->val4; + + out->ptr = in->ptr; + out->val1 = in->val1; + out->val2 = in->val2; + out->val3 = in->val3; + out->val4 = in->val4; + + return 0; +} + +SEC("raw_tp/sys_exit") +int handle_downsize(void *ctx) +{ + struct test_struct___downsize *in = (void *)&input; + struct test_struct___downsize *out = (void *)&output_downsized; + + ptr_downsized = (unsigned long long)in->ptr; + val1_downsized = in->val1; + val2_downsized = in->val2; + val3_downsized = in->val3; + val4_downsized = in->val4; + + out->ptr = in->ptr; + out->val1 = in->val1; + out->val2 = in->val2; + out->val3 = in->val3; + out->val4 = in->val4; + + return 0; +} + +SEC("raw_tp/sys_enter") +int handle_probed(void *ctx) +{ + struct test_struct___downsize *in = (void *)&input; + __u64 tmp; + + tmp = 0; + bpf_core_read(&tmp, bpf_core_field_size(in->ptr), &in->ptr); + ptr_probed = tmp; + + tmp = 0; + bpf_core_read(&tmp, bpf_core_field_size(in->val1), &in->val1); + val1_probed = tmp; + + tmp = 0; + bpf_core_read(&tmp, bpf_core_field_size(in->val2), &in->val2); + val2_probed = tmp; + + tmp = 0; + bpf_core_read(&tmp, bpf_core_field_size(in->val3), &in->val3); + val3_probed = tmp; + + tmp = 0; + bpf_core_read(&tmp, bpf_core_field_size(in->val4), &in->val4); + val4_probed = tmp; + + return 0; +} + +SEC("raw_tp/sys_enter") +int handle_signed(void *ctx) +{ + struct test_struct___signed *in = (void *)&input; + struct test_struct___signed *out = (void *)&output_signed; + + val2_signed = in->val2; + val3_signed = in->val3; + val4_signed = in->val4; + + out->val2= in->val2; + out->val3= in->val3; + out->val4= in->val4; + + return 0; +}