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[192.26.29.3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49e7d6a8d5asm19427095e9.9.2026.09.14.15.25.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Sep 2026 15:25:23 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , Emil Tsalapatis , Nicholas Carlini , kkd@meta.com, kernel-team@meta.com Subject: [PATCH bpf v4 05/11] selftests/bpf: Test early in-kernel CO-RE relocation Date: Tue, 15 Sep 2026 00:25:02 +0200 Message-ID: <20260914222514.1635018-6-memxor@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260914222514.1635018-1-memxor@gmail.com> References: <20260914222514.1635018-1-memxor@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5801; i=memxor@gmail.com; h=from:subject; bh=sPPlAO2GpP6ZT11W4B6oE0Ekzhisk6AHjjJsYcpc9qQ=; b=owGbwMvMwCXmrmtenRyi38x4Wi2JIWtFiZ5c0l399u3rhVpv/N75KP+0/I8V/SJTjGrTFE24P 2bllN7oKGVhEONikBVTZCn5v4/J+ETl70DbZdwwc1iZQIYwcHEKwERuWjP8s7s5M0FmErf2vueM JpuOepZ8fsWgoFmWJPBmqW/vN/cT3IwMu+ef8ZRUCXvFwlzyOONpu6Y144mtE3u23Dz368XD7Lr v3AA= X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=B34BD741DE8494B76E2F717880EF20021D46C59B Content-Transfer-Encoding: 8bit Add a raw program load with CO-RE relocation metadata but no func_info or line_info. Place the relocation in dead code and require the poisoning log, proving that the kernel processes standalone CO-RE metadata instead of silently skipping it. Also poison a subprogram's terminal exit and require check_subprogs() to reject the resulting fall-through. This confirms that in-kernel CO-RE runs before the verifier validates the subprogram layout and before later CFG consumers rely on it. Load both instruction streams without relocation metadata first to ensure that CO-RE processing causes the rejection and diagnostic. Signed-off-by: Kumar Kartikeya Dwivedi --- .../selftests/bpf/prog_tests/core_reloc_raw.c | 128 ++++++++++++++++++ 1 file changed, 128 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc_raw.c b/tools/testing/selftests/bpf/prog_tests/core_reloc_raw.c index a18d3680fb16..6fdeba6d7eaa 100644 --- a/tools/testing/selftests/bpf/prog_tests/core_reloc_raw.c +++ b/tools/testing/selftests/bpf/prog_tests/core_reloc_raw.c @@ -14,6 +14,133 @@ static char log[16 * 1024]; +static int load_core_relo_insns(int btf_fd, struct bpf_insn *insns, int insn_cnt, + struct bpf_func_info *funcs, int func_cnt, + int enum_id, int access_str_off, int insn_idx, + bool relocate) +{ + struct bpf_core_relo relo = { + .insn_off = insn_idx * sizeof(struct bpf_insn), + .type_id = enum_id, + .access_str_off = access_str_off, + .kind = BPF_CORE_ENUMVAL_VALUE, + }; + union bpf_attr attr = { + .prog_type = BPF_PROG_TYPE_SOCKET_FILTER, + .insn_cnt = insn_cnt, + .insns = (__u64)insns, + .license = (__u64)"GPL", + .log_buf = (__u64)log, + .log_size = sizeof(log), + .log_level = 2, + .prog_btf_fd = btf_fd, + .func_info_rec_size = sizeof(struct bpf_func_info), + .func_info = (__u64)funcs, + .func_info_cnt = func_cnt, + }; + + if (relocate) { + attr.core_relo_cnt = 1; + attr.core_relos = (__u64)&relo; + attr.core_relo_rec_size = sizeof(relo); + } + memset(log, 0, sizeof(log)); + return sys_bpf_prog_load(&attr, sizeof(attr), 1); +} + +static void test_early_core_relo(void) +{ + struct bpf_insn core_only[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + struct bpf_insn subprog[] = { + BPF_CALL_REL(2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + struct bpf_func_info funcs[2]; + const void *raw_btf; + struct btf *btf; + __u32 raw_btf_size; + int access_str_off, btf_fd = -1, enum_id; + int int_id, main_id, prog_fd = -1, proto_id, sub_id; + + btf = btf__new_empty(); + if (!ASSERT_OK_PTR(btf, "btf_new_empty")) + return; + int_id = btf__add_int(btf, "int", 4, BTF_INT_SIGNED); + if (!ASSERT_GT(int_id, 0, "add_int")) + goto cleanup; + proto_id = btf__add_func_proto(btf, int_id); + if (!ASSERT_GT(proto_id, 0, "add_func_proto")) + goto cleanup; + main_id = btf__add_func(btf, "main_fn", BTF_FUNC_STATIC, proto_id); + if (!ASSERT_GT(main_id, 0, "add_main_func")) + goto cleanup; + sub_id = btf__add_func(btf, "sub_fn", BTF_FUNC_STATIC, proto_id); + if (!ASSERT_GT(sub_id, 0, "add_sub_func")) + goto cleanup; + enum_id = btf__add_enum(btf, "core_relo_poison_missing", 4); + if (!ASSERT_GT(enum_id, 0, "add_enum") || + !ASSERT_OK(btf__add_enum_value(btf, "value", 0), "add_enum_value")) + goto cleanup; + access_str_off = btf__add_str(btf, "0"); + if (!ASSERT_GT(access_str_off, 0, "add_access_str")) + goto cleanup; + + raw_btf = btf__raw_data(btf, &raw_btf_size); + if (!ASSERT_OK_PTR(raw_btf, "raw_btf")) + goto cleanup; + btf_fd = bpf_btf_load(raw_btf, raw_btf_size, NULL); + if (!ASSERT_GE(btf_fd, 0, "btf_load")) + goto cleanup; + funcs[0] = (struct bpf_func_info) { .insn_off = 0, .type_id = main_id }; + funcs[1] = (struct bpf_func_info) { .insn_off = 3, .type_id = sub_id }; + + if (test__start_subtest("without_func_info")) { + prog_fd = load_core_relo_insns(btf_fd, core_only, ARRAY_SIZE(core_only), NULL, 0, + enum_id, access_str_off, 2, false); + if (!ASSERT_GE(prog_fd, 0, "control_load")) + goto cleanup; + close(prog_fd); + prog_fd = load_core_relo_insns(btf_fd, core_only, ARRAY_SIZE(core_only), NULL, 0, + enum_id, access_str_off, 2, true); + if (!ASSERT_GE(prog_fd, 0, "poisoned_load")) + goto cleanup; + ASSERT_HAS_SUBSTR(log, "substituting insn #2", "poison_log"); + close(prog_fd); + prog_fd = -1; + } + + if (test__start_subtest("poisoned_subprog_terminator")) { + prog_fd = load_core_relo_insns(btf_fd, subprog, ARRAY_SIZE(subprog), funcs, 2, + enum_id, access_str_off, 2, false); + if (!ASSERT_GE(prog_fd, 0, "control_load")) + goto cleanup; + close(prog_fd); + prog_fd = load_core_relo_insns(btf_fd, subprog, ARRAY_SIZE(subprog), funcs, 2, + enum_id, access_str_off, 2, true); + if (!ASSERT_LT(prog_fd, 0, "poisoned_load")) + goto cleanup; + ASSERT_HAS_SUBSTR(log, "last insn is not an exit or jmp", "poisoned_load_log"); + } + +cleanup: + if (env.verbosity > VERBOSE_NORMAL && log[0]) { + printf("-------- program load log start --------\n"); + printf("%s", log); + printf("-------- program load log end ----------\n"); + } + close(prog_fd); + close(btf_fd); + btf__free(btf); +} + /* Check that verifier rejects BPF program containing relocation * pointing to non-existent BTF type. */ @@ -120,6 +247,7 @@ static void test_bad_local_id(void) void test_core_reloc_raw(void) { + test_early_core_relo(); if (test__start_subtest("bad_local_id")) test_bad_local_id(); } -- 2.53.0