From patchwork Wed Nov 30 06:54:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viktor Malik X-Patchwork-Id: 13059488 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 232C4C433FE for ; Wed, 30 Nov 2022 06:55:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232933AbiK3GzW (ORCPT ); Wed, 30 Nov 2022 01:55:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232771AbiK3GzV (ORCPT ); Wed, 30 Nov 2022 01:55:21 -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 D05F14B77D for ; Tue, 29 Nov 2022 22:54:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669791261; 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=2GgiL2uUehFeSY01/5xS/jsuIOB0GqA8H4qC4ZB37mA=; b=YJ53k7FCf95NLCf3WNF6nT6HcEYmo+PZcM+MlDFl+MzwfwD9v7FfpAUPiqs614riaDDRRS dKn/610nDzGiXzrTQohs9rPEmTDXLBrhA7YbNFnWvRNxlQmVu3Wx1CboTr9yPSG2o91f8U EtjDy5cb7Ng6xieyeYq5tf+dOjzOSME= 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-122-IjyMXwJVO4ecXW6Emge_iw-1; Wed, 30 Nov 2022 01:54:16 -0500 X-MC-Unique: IjyMXwJVO4ecXW6Emge_iw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 72F0E1C008A5; Wed, 30 Nov 2022 06:54:15 +0000 (UTC) Received: from ovpn-192-146.brq.redhat.com (ovpn-192-146.brq.redhat.com [10.40.192.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8F8D5C15BA4; Wed, 30 Nov 2022 06:54:12 +0000 (UTC) From: Viktor Malik To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Viktor Malik Subject: [PATCH bpf-next v2 1/3] kallsyms: add space-efficient lookup in one module Date: Wed, 30 Nov 2022 07:54:02 +0100 Message-Id: <2036e115623b527dd78b22f487a35ddceb512006.1669787912.git.vmalik@redhat.com> In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Until now, the only way to look up a symbol in kallsyms of a particular module was using the "module_kallsyms_lookup_name" function with the "module:symbol" string passed as a parameter. This syntax often requires to build the parameter string on stack, needlessly wasting space. This commit introduces function "kallsyms_lookup_name_in_module" which takes the module and the symbol names as separate parameters and therefore allows more space-efficient lookup. Signed-off-by: Viktor Malik --- include/linux/module.h | 1 + kernel/module/kallsyms.c | 16 ++++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/include/linux/module.h b/include/linux/module.h index 35876e89eb93..fe5dfb6bd288 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -605,6 +605,7 @@ struct module *find_module(const char *name); int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type, char *name, char *module_name, int *exported); +unsigned long kallsyms_lookup_name_in_module(const char *module_name, const char *name); /* Look for this name: can be of form module:name. */ unsigned long module_kallsyms_lookup_name(const char *name); diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c index 4523f99b0358..c6c8227c7a45 100644 --- a/kernel/module/kallsyms.c +++ b/kernel/module/kallsyms.c @@ -482,6 +482,22 @@ static unsigned long __module_kallsyms_lookup_name(const char *name) return 0; } +unsigned long kallsyms_lookup_name_in_module(const char *module_name, const char *name) +{ + unsigned long ret; + struct module *mod; + + preempt_disable(); + mod = find_module_all(module_name, strlen(module_name), false); + if (mod) + ret = find_kallsyms_symbol_value(mod, name); + else + ret = 0; + preempt_enable(); + return ret; + +} + /* Look for this name: can be of form module:name. */ unsigned long module_kallsyms_lookup_name(const char *name) { From patchwork Wed Nov 30 06:54:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viktor Malik X-Patchwork-Id: 13059487 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 1A635C352A1 for ; Wed, 30 Nov 2022 06:55:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229584AbiK3GzU (ORCPT ); Wed, 30 Nov 2022 01:55:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229648AbiK3GzT (ORCPT ); Wed, 30 Nov 2022 01:55:19 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E61A14F18F for ; Tue, 29 Nov 2022 22:54:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669791264; 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=c9O5Aw7tkF9mUe77O9dqtCDvw6APFkrLSv7rvkAGt38=; b=BWTBEI+BdvL1AabbxDoio7yib89kM8Sk3VLLEZeD0KA8fHeTR9782483I8cifxpyKYcTa+ 9A5Jdgj1bUp1XbOf+90YXDyIdnH73J7p+Qjp1Dl2qsxZVNwnsyV49c2LJGnBGh4KsTz8LH NZKGWX5fBH2zT0cGANsXPfUUf3ief5k= 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-13-nPNW590aMYaz0czb1SnYvA-1; Wed, 30 Nov 2022 01:54:19 -0500 X-MC-Unique: nPNW590aMYaz0czb1SnYvA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E8AFC38123A0; Wed, 30 Nov 2022 06:54:18 +0000 (UTC) Received: from ovpn-192-146.brq.redhat.com (ovpn-192-146.brq.redhat.com [10.40.192.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D3152C15BA4; Wed, 30 Nov 2022 06:54:15 +0000 (UTC) From: Viktor Malik To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Viktor Malik Subject: [PATCH bpf-next v2 2/3] bpf: Fix attaching fentry/fexit/fmod_ret/lsm to modules Date: Wed, 30 Nov 2022 07:54:03 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 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 Acked-by: Hao Luo --- include/linux/btf.h | 1 + kernel/bpf/btf.c | 5 +++++ kernel/bpf/verifier.c | 5 ++++- 3 files changed, 10 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 d11cbf8cece7..2815944ddfa4 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7206,6 +7206,11 @@ 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 4e7f1d085e53..41f6a8722a97 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -16451,7 +16451,10 @@ 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)) + addr = kallsyms_lookup_name_in_module(btf_module_name(btf), tname); + else + addr = kallsyms_lookup_name(tname); if (!addr) { bpf_log(log, "The address of function %s cannot be found\n", From patchwork Wed Nov 30 06:54:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viktor Malik X-Patchwork-Id: 13059489 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 E18C2C4321E for ; Wed, 30 Nov 2022 06:55:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233244AbiK3Gz0 (ORCPT ); Wed, 30 Nov 2022 01:55:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232771AbiK3GzY (ORCPT ); Wed, 30 Nov 2022 01:55:24 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFEF64FF97 for ; Tue, 29 Nov 2022 22:54:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669791266; 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=uKvjKCdmkZB6NQ/bdjjalHt9P1pJFFM/EqdFh8BTkbY=; b=YvmPSZaFBpuwcgvHvjB35kBgA/R1e9NH0F7Ivr14YKY0zC6K3k/j5pRrGHavWx5XFgiV1h zsUo/EOkcaD90/22+sRSb2EyJWUo3ccons/hIGORssErsg2AURjupDLD+uGCy9pOKHugdc u2NNUG+q7SRKlDCPc/gYBxhkgcVvmNA= 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-377-2nrbtzccNauNJrhfJMBBjA-1; Wed, 30 Nov 2022 01:54:22 -0500 X-MC-Unique: 2nrbtzccNauNJrhfJMBBjA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E0B1E185A794; Wed, 30 Nov 2022 06:54:21 +0000 (UTC) Received: from ovpn-192-146.brq.redhat.com (ovpn-192-146.brq.redhat.com [10.40.192.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5476CC15BA4; Wed, 30 Nov 2022 06:54:19 +0000 (UTC) From: Viktor Malik To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Viktor Malik Subject: [PATCH bpf-next v2 3/3] bpf/selftests: Test fentry attachment to shadowed functions Date: Wed, 30 Nov 2022 07:54:04 +0100 Message-Id: <0f12de29c72a83fa420df795804fdf7a82be0608.1669787912.git.vmalik@redhat.com> In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 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 | 124 ++++++++++++++++++ 3 files changed, 136 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 6094ef7cffcd..71e36a85573b 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..bf511e61ec1f --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/module_attach_shadow.c @@ -0,0 +1,124 @@ +// 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 = 0, 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 = NULL, *mod_btf = NULL; + 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")) + goto out; + + 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_kind(vmlinux_btf, symbol_name, BTF_KIND_FUNC); + if (!ASSERT_GT(btf_id[0], 0, "btf_find_by_name")) + goto out; + + btf_id[1] = btf__find_by_name_kind(mod_btf, symbol_name, BTF_KIND_FUNC); + 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: + if (vmlinux_btf) + btf__free(vmlinux_btf); + if (mod_btf) + btf__free(mod_btf); + 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]); + } +}