From patchwork Fri Apr 28 09:51:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Wenlong X-Patchwork-Id: 13226185 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 22D52C77B7F for ; Fri, 28 Apr 2023 09:56:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346009AbjD1J4m (ORCPT ); Fri, 28 Apr 2023 05:56:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345778AbjD1J4M (ORCPT ); Fri, 28 Apr 2023 05:56:12 -0400 Received: from out0-210.mail.aliyun.com (out0-210.mail.aliyun.com [140.205.0.210]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D9B25599; Fri, 28 Apr 2023 02:55:19 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R371e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018047213;MF=houwenlong.hwl@antgroup.com;NM=1;PH=DS;RN=21;SR=0;TI=SMTPD_---.STFoGdv_1682675616; Received: from localhost(mailfrom:houwenlong.hwl@antgroup.com fp:SMTPD_---.STFoGdv_1682675616) by smtp.aliyun-inc.com; Fri, 28 Apr 2023 17:53:37 +0800 From: "Hou Wenlong" To: linux-kernel@vger.kernel.org Cc: "Thomas Garnier" , "Lai Jiangshan" , "Kees Cook" , "Hou Wenlong" , "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "Dave Hansen" , , "H. Peter Anvin" , "Masahiro Yamada" , "Nathan Chancellor" , "Nick Desaulniers" , "Nicolas Schier" , "Josh Poimboeuf" , "Peter Zijlstra" , "Christophe Leroy" , "Sathvika Vasireddy" , " =?utf-8?q?Thomas_Wei=C3=9Fschuh?= " , Subject: [PATCH RFC 33/43] objtool: Add validation for x86 PIE support Date: Fri, 28 Apr 2023 17:51:13 +0800 Message-Id: <226af8c63c5bfa361763dd041a997ee84fe926cf.1682673543.git.houwenlong.hwl@antgroup.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org For x86 PIE binary, only RIP-relative addressing is allowed, however, there are still a little absolute references of R_X86_64_64 relocation type for data section and a little absolute references of R_X86_64_32S relocation type in pvh_start_xen() function. Suggested-by: Lai Jiangshan Signed-off-by: Hou Wenlong Cc: Thomas Garnier Cc: Kees Cook --- arch/x86/Kconfig | 1 + scripts/Makefile.lib | 1 + tools/objtool/builtin-check.c | 4 +- tools/objtool/check.c | 82 +++++++++++++++++++++++++ tools/objtool/include/objtool/builtin.h | 1 + 5 files changed, 88 insertions(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 715f0734d065..b753a54e5ea7 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2224,6 +2224,7 @@ config RELOCATABLE config X86_PIE def_bool n depends on X86_64 + select OBJTOOL if HAVE_OBJTOOL config RANDOMIZE_BASE bool "Randomize the address of the kernel image (KASLR)" diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 100a386fcd71..e3c804fbc421 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -270,6 +270,7 @@ objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE) += --static-call objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION) += --uaccess objtool-args-$(CONFIG_GCOV_KERNEL) += --no-unreachable objtool-args-$(CONFIG_PREFIX_SYMBOLS) += --prefix=$(CONFIG_FUNCTION_PADDING_BYTES) +objtool-args-$(CONFIG_X86_PIE) += --pie objtool-args = $(objtool-args-y) \ $(if $(delay-objtool), --link) \ diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c index 7c175198d09f..1cf1d00464e0 100644 --- a/tools/objtool/builtin-check.c +++ b/tools/objtool/builtin-check.c @@ -81,6 +81,7 @@ static const struct option check_options[] = { OPT_BOOLEAN('t', "static-call", &opts.static_call, "annotate static calls"), OPT_BOOLEAN('u', "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"), OPT_BOOLEAN(0 , "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"), + OPT_BOOLEAN(0, "pie", &opts.pie, "validate addressing rules for PIE"), OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump), OPT_GROUP("Options:"), @@ -137,7 +138,8 @@ static bool opts_valid(void) opts.sls || opts.stackval || opts.static_call || - opts.uaccess) { + opts.uaccess || + opts.pie) { if (opts.dump_orc) { ERROR("--dump can't be combined with other options"); return false; diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 5b600bbf2389..d67b80251eec 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -131,6 +131,27 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file, for (insn = next_insn_same_sec(file, insn); insn; \ insn = next_insn_same_sec(file, insn)) +static struct instruction *find_insn_containing(struct objtool_file *file, + struct section *sec, + unsigned long offset) +{ + struct instruction *insn; + + insn = find_insn(file, sec, 0); + if (!insn) + return NULL; + + sec_for_each_insn_from(file, insn) { + if (insn->offset > offset) + return NULL; + if (insn->offset <= offset && (insn->offset + insn->len) > offset) + return insn; + } + + return NULL; +} + + static inline struct symbol *insn_call_dest(struct instruction *insn) { if (insn->type == INSN_JUMP_DYNAMIC || @@ -4529,6 +4550,61 @@ static int validate_reachable_instructions(struct objtool_file *file) return 0; } +static int is_in_pvh_code(struct instruction *insn) +{ + struct symbol *sym = insn->sym; + + return sym && !strcmp(sym->name, "pvh_start_xen"); +} + +static int validate_pie(struct objtool_file *file) +{ + struct section *sec; + struct reloc *reloc; + struct instruction *insn; + int warnings = 0; + + for_each_sec(file, sec) { + if (!sec->reloc) + continue; + if (!(sec->sh.sh_flags & SHF_ALLOC)) + continue; + + list_for_each_entry(reloc, &sec->reloc->reloc_list, list) { + switch (reloc->type) { + case R_X86_64_NONE: + case R_X86_64_PC32: + case R_X86_64_PLT32: + case R_X86_64_64: + case R_X86_64_PC64: + case R_X86_64_GOTPCREL: + break; + case R_X86_64_32: + case R_X86_64_32S: + insn = find_insn_containing(file, sec, reloc->offset); + if (!insn) { + WARN("can't find relocate insn near %s+0x%lx", + sec->name, reloc->offset); + } else { + if (is_in_pvh_code(insn)) + break; + WARN("insn at %s+0x%lx is not compatible with PIE", + sec->name, insn->offset); + } + warnings++; + break; + default: + WARN("unexpected relocation type %d at %s+0x%lx", + reloc->type, sec->name, reloc->offset); + warnings++; + break; + } + } + } + + return warnings; +} + int check(struct objtool_file *file) { int ret, warnings = 0; @@ -4673,6 +4749,12 @@ int check(struct objtool_file *file) warnings += ret; } + if (opts.pie) { + ret = validate_pie(file); + if (ret < 0) + return ret; + warnings += ret; + } if (opts.stats) { printf("nr_insns_visited: %ld\n", nr_insns_visited); diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h index 2a108e648b7a..1151211a5cea 100644 --- a/tools/objtool/include/objtool/builtin.h +++ b/tools/objtool/include/objtool/builtin.h @@ -26,6 +26,7 @@ struct opts { bool uaccess; int prefix; bool cfi; + bool pie; /* options: */ bool backtrace;