From patchwork Mon Nov 28 07:26:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viktor Malik X-Patchwork-Id: 13057093 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0D25C4321E for ; Mon, 28 Nov 2022 07:27:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229970AbiK1H1j (ORCPT ); Mon, 28 Nov 2022 02:27:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229968AbiK1H1i (ORCPT ); Mon, 28 Nov 2022 02:27:38 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F6E4A463 for ; Sun, 27 Nov 2022 23:26:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669620406; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6zK6dP0XpiEvbMh+MStSVKQQA+Ww92c90Z58azKzrgE=; b=SzM3zGMFDcFA9pOuvWH86DbE2rj0QNAsCVA/NrKJZHNv0QD9wMMp3BoIovOEGFKVqNWPT3 zqWsOWc186CfCvFHlKS1DYhGs7wY4jxxLkm9niMxZS7ImguCFZ/PbbbJgMIhEFYipT7+Z3 7wyOs3tZnMGnkLFTJnNk5e4o4vJOqPU= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-308-UDWKSn34O86X-WCGqCa-1g-1; Mon, 28 Nov 2022 02:26:45 -0500 X-MC-Unique: UDWKSn34O86X-WCGqCa-1g-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5DDF929AA3B5; Mon, 28 Nov 2022 07:26:44 +0000 (UTC) Received: from ovpn-192-85.brq.redhat.com (ovpn-192-85.brq.redhat.com [10.40.192.85]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 620EC1415100; Mon, 28 Nov 2022 07:26:41 +0000 (UTC) From: Viktor Malik To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Viktor Malik Subject: [PATCH bpf-next 1/2] bpf: Fix attaching fentry/fexit/fmod_ret/lsm to modules Date: Mon, 28 Nov 2022 08:26:29 +0100 Message-Id: <2ec861621e283ba2a54f7e939eafed1c29f77bf4.1669216157.git.vmalik@redhat.com> In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net When attaching fentry/fexit/fmod_ret/lsm to a function located in a module without specifying the target program, the verifier tries to find the address to attach to in kallsyms. This is always done by searching the entire kallsyms, not respecting the module in which the function is located. This approach causes an incorrect attachment address to be computed if the function to attach to is shadowed by a function of the same name located earlier in kallsyms. Since the attachment must contain the BTF of the program to attach to, we may extract the module name from it (if the attach target is a module) and search for the function address in the correct module. Signed-off-by: Viktor Malik --- include/linux/btf.h | 1 + kernel/bpf/btf.c | 5 +++++ kernel/bpf/verifier.c | 9 ++++++++- 3 files changed, 14 insertions(+), 1 deletion(-) diff --git a/include/linux/btf.h b/include/linux/btf.h index 9ed00077db6e..bdbf3eb7083d 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -187,6 +187,7 @@ u32 btf_obj_id(const struct btf *btf); bool btf_is_kernel(const struct btf *btf); bool btf_is_module(const struct btf *btf); struct module *btf_try_get_module(const struct btf *btf); +const char *btf_module_name(const struct btf *btf); u32 btf_nr_types(const struct btf *btf); bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s, const struct btf_member *m, diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 1a59cc7ad730..211fcbb7649d 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7192,6 +7192,11 @@ bool btf_is_module(const struct btf *btf) return btf->kernel_btf && strcmp(btf->name, "vmlinux") != 0; } +const char *btf_module_name(const struct btf *btf) +{ + return btf->name; +} + enum { BTF_MODULE_F_LIVE = (1 << 0), }; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9528a066cfa5..acbe62a73559 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -16343,7 +16343,14 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, else addr = (long) tgt_prog->aux->func[subprog]->bpf_func; } else { - addr = kallsyms_lookup_name(tname); + if (btf_is_module(btf)) { + char tmodname[MODULE_NAME_LEN + KSYM_NAME_LEN + 1]; + snprintf(tmodname, sizeof(tmodname), "%s:%s", + btf_module_name(btf), tname); + addr = module_kallsyms_lookup_name(tmodname); + } + else + addr = kallsyms_lookup_name(tname); if (!addr) { bpf_log(log, "The address of function %s cannot be found\n", From patchwork Mon Nov 28 07:26:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viktor Malik X-Patchwork-Id: 13057095 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E68CC433FE for ; Mon, 28 Nov 2022 07:27:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229968AbiK1H1w (ORCPT ); Mon, 28 Nov 2022 02:27:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229895AbiK1H1t (ORCPT ); Mon, 28 Nov 2022 02:27:49 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41D1BE02B for ; Sun, 27 Nov 2022 23:26:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669620413; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=e8ytY21q/YryZwHknqopljYvoEmkOAdNAqVplN7LiC8=; b=IKyEsktFaTU0rNiv7Qk5uAc0SaY2XkZhZzYAECBLdNlK7QPTfXzMVDvx6fm3hb5GMvU5L4 zCnj3zwIO3z0CCxcsMZ7AjbUgIINkT/JSjna6iAR2Gr7plJiZ3uUeX5KI023/+/fk0IX7a +6eVb7Vd8+n4NT/etmpXOxgyetNcn1Y= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-58-XwUahPz2Mxa8tW-AgZzjHA-1; Mon, 28 Nov 2022 02:26:48 -0500 X-MC-Unique: XwUahPz2Mxa8tW-AgZzjHA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 610D1811E67; Mon, 28 Nov 2022 07:26:47 +0000 (UTC) Received: from ovpn-192-85.brq.redhat.com (ovpn-192-85.brq.redhat.com [10.40.192.85]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BE9A11415100; Mon, 28 Nov 2022 07:26:44 +0000 (UTC) From: Viktor Malik To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Viktor Malik Subject: [PATCH bpf-next 2/2] bpf/selftests: Test fentry attachment to shadowed functions Date: Mon, 28 Nov 2022 08:26:30 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Adds a new test that tries to attach a program to fentry of two functions of the same name, one located in vmlinux and the other in bpf_testmod. To avoid conflicts with existing tests, a new function "bpf_fentry_shadow_test" was created both in vmlinux and in bpf_testmod. The previous commit fixed a bug which caused this test to fail. The verifier would always use the vmlinux function's address as the target trampoline address, hence trying to attach two programs to the same trampoline. Signed-off-by: Viktor Malik --- net/bpf/test_run.c | 5 + .../selftests/bpf/bpf_testmod/bpf_testmod.c | 7 + .../bpf/prog_tests/module_attach_shadow.c | 120 ++++++++++++++++++ 3 files changed, 132 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/module_attach_shadow.c diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 6fba440efc40..c60e46b1e768 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -536,6 +536,11 @@ int noinline bpf_modify_return_test(int a, int *b) return a + *b; } +int noinline bpf_fentry_shadow_test(int a) +{ + return a + 1; +} + u64 noinline bpf_kfunc_call_test1(struct sock *sk, u32 a, u64 b, u32 c, u64 d) { return a + b + c + d; diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c index 5085fea3cac5..d23127a5ec68 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c @@ -229,6 +229,13 @@ static const struct btf_kfunc_id_set bpf_testmod_kfunc_set = { .set = &bpf_testmod_check_kfunc_ids, }; +noinline int bpf_fentry_shadow_test(int a) +{ + return a + 2; +} +EXPORT_SYMBOL_GPL(bpf_fentry_shadow_test); +ALLOW_ERROR_INJECTION(bpf_fentry_shadow_test, ERRNO); + extern int bpf_fentry_test1(int a); static int bpf_testmod_init(void) diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach_shadow.c b/tools/testing/selftests/bpf/prog_tests/module_attach_shadow.c new file mode 100644 index 000000000000..0c604a0f22ca --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/module_attach_shadow.c @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Red Hat */ +#include +#include +#include "bpf/libbpf_internal.h" +#include "cgroup_helpers.h" + +static const char *module_name = "bpf_testmod"; +static const char *symbol_name = "bpf_fentry_shadow_test"; + +int get_bpf_testmod_btf_fd(void) +{ + struct bpf_btf_info info; + char name[64]; + __u32 id, len; + int err, fd; + + while (true) { + err = bpf_btf_get_next_id(id, &id); + if (err) { + log_err("failed to iterate BTF objects"); + return err; + } + + fd = bpf_btf_get_fd_by_id(id); + if (fd < 0) { + err = -errno; + log_err("failed to get FD for BTF object #%d", id); + return err; + } + + len = sizeof(info); + memset(&info, 0, sizeof(info)); + info.name = ptr_to_u64(name); + info.name_len = sizeof(name); + + err = bpf_obj_get_info_by_fd(fd, &info, &len); + if (err) { + err = -errno; + log_err("failed to get info for BTF object #%d", id); + close(fd); + return err; + } + + if (strcmp(name, module_name) == 0) + return fd; + + close(fd); + } + return -ENOENT; +} + +void test_module_fentry_shadow(void) +{ + struct btf *vmlinux_btf, *mod_btf; + int err, i; + int btf_fd[2] = {}; + int prog_fd[2] = {}; + int link_fd[2] = {}; + __s32 btf_id[2] = {}; + + const struct bpf_insn trace_program[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + + LIBBPF_OPTS(bpf_prog_load_opts, load_opts, + .expected_attach_type = BPF_TRACE_FENTRY, + ); + + LIBBPF_OPTS(bpf_test_run_opts, test_opts); + + vmlinux_btf = btf__load_vmlinux_btf(); + if (!ASSERT_OK_PTR(vmlinux_btf, "load_vmlinux_btf")) + return; + + btf_fd[1] = get_bpf_testmod_btf_fd(); + if (!ASSERT_GT(btf_fd[1], 0, "get_bpf_testmod_btf_fd")) + return; + + mod_btf = btf_get_from_fd(btf_fd[1], vmlinux_btf); + if (!ASSERT_OK_PTR(mod_btf, "btf_get_from_fd")) + goto out; + + btf_id[0] = btf__find_by_name(vmlinux_btf, symbol_name); + if (!ASSERT_GT(btf_id[0], 0, "btf_find_by_name")) + goto out; + + btf_id[1] = btf__find_by_name(mod_btf, symbol_name); + if (!ASSERT_GT(btf_id[1], 0, "btf_find_by_name")) + goto out; + + for (i = 0; i < 2; i++) { + load_opts.attach_btf_id = btf_id[i]; + load_opts.attach_btf_obj_fd = btf_fd[i]; + prog_fd[i] = bpf_prog_load(BPF_PROG_TYPE_TRACING, NULL, "GPL", + trace_program, + sizeof(trace_program) / sizeof(struct bpf_insn), + &load_opts); + if (!ASSERT_GE(prog_fd[i], 0, "bpf_prog_load")) + goto out; + + link_fd[i] = bpf_link_create(prog_fd[i], 0, BPF_TRACE_FENTRY, NULL); + if (!ASSERT_GE(link_fd[i], 0, "bpf_link_create")) + goto out; + } + + err = bpf_prog_test_run_opts(prog_fd[0], &test_opts); + ASSERT_OK(err, "running test"); + +out: + for (i = 0; i < 2; i++) { + if (btf_fd[i]) + close(btf_fd[i]); + if (prog_fd[i]) + close(prog_fd[i]); + if (link_fd[i]) + close(link_fd[i]); + } +}