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Lu" X-Patchwork-Id: 942264 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=sourceware.org (client-ip=209.132.180.131; helo=sourceware.org; envelope-from=libc-alpha-return-94151-incoming=patchwork.ozlabs.org@sourceware.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.b="INLaJKQP"; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="ADMOPK1/"; dkim-atps=neutral Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 41QGb811hVz9s2L for ; Wed, 11 Jul 2018 08:09:54 +1000 (AEST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:mime-version:from:date:message-id:subject:to :cc:content-type; q=dns; s=default; b=kNuYp6HgtNoJZXtbv+POJjSNC7 soWXo/BKtg6UMPnPmxDGHRIDVrGcdYaorm9bD0KQwhMELuZIVUbIr+0uQDbzIHTu uHjubzstGGzbwiBYaGUB68hE8uZcT1lu++G8kVzcu/2zAp/EYaNa5aNIuTFxE6dl RHuwfCD3FJTbv204o= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:mime-version:from:date:message-id:subject:to :cc:content-type; s=default; bh=m6ggiShBUGrvuiw/CdbzJTKz/4k=; b= INLaJKQP2MfJrAB1qRzRid6BnfiJztw6ZJOsXLPZuh6ZucCX7yXegA1CzgFCrigZ ywoEaSHEPf1GwUq/AOt20TEHnKuTjXn7WRxX7CFIGxftZQ5GwzUz0fIz3tp+vWn3 VJ5oYTez2QP+r/nqnHIanzV6gHQ1he3EXWBgElKPjCs= Received: (qmail 120361 invoked by alias); 10 Jul 2018 22:09:48 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 120351 invoked by uid 89); 10 Jul 2018 22:09:47 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-25.3 required=5.0 tests=AWL, BAYES_00, FREEMAIL_FROM, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_PASS autolearn=ham version=3.3.2 spammy=T, Tracking, chances, incorporate X-HELO: mail-oi0-f68.google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc; bh=EiH022lDQrCtVcaR17/X1uN0mToCQ8ZNVKKrO2vMyF4=; b=ADMOPK1/GM8nh8DfIMbSqC/dJp/Rp0UTcmrDvll9q8SAp5zO6BOXN8Ewn+KWKnWDCP H9uxxV941/D1yOFtWBsXqpznb6Nfkk5TGaSarmVn39XGMkCNEhBSilGxL9F1o2slDWs3 59BUziL6jxyc4ELLf17Gnmnf2eK+PLAtTYsr7SHeluMHgWKB4LTbu9O0WIkheRRnCBhh 3tBZDxOCfjCFwoLsP4Q+FxjxiryWD5CnHsSKkMg1J9udAOZYXqK2Ws+4aMv2KV5iB6dn UytRzZ7iXIPnDOoz/BcpJXcEvvFLsvS4rwDz8HbTjAZhRlsxq21AWxXCLomNg1eYI72u J+RA== MIME-Version: 1.0 From: "H.J. Lu" Date: Tue, 10 Jul 2018 15:09:37 -0700 Message-ID: Subject: V3 [PATCH 03/24] x86: Support IBT and SHSTK in Intel CET [BZ #21598] To: "Carlos O'Donell" Cc: GNU C Library On Sat, Jul 7, 2018 at 1:01 PM, H.J. Lu wrote: > On Fri, Jul 06, 2018 at 03:47:27PM -0400, Carlos O'Donell wrote: >> On 06/13/2018 11:31 AM, H.J. Lu wrote: >> > Intel Control-flow Enforcement Technology (CET) instructions: >> >> Reviewed. >> >> Looking forward to v2. >> Here is V3. The difference from V2 is that get_cet_status became: static inline int __attribute__ ((always_inline)) get_cet_status (void) { return 0; } Reviewed-by: Carlos O'Donell From b100bb5197020c403bf53f26b94324d04e4a0d45 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Thu, 22 Jun 2017 04:15:39 -0700 Subject: [PATCH 03/24] x86: Support IBT and SHSTK in Intel CET [BZ #21598] Intel Control-flow Enforcement Technology (CET) instructions: https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-en forcement-technology-preview.pdf includes Indirect Branch Tracking (IBT) and Shadow Stack (SHSTK). GNU_PROPERTY_X86_FEATURE_1_IBT is added to GNU program property to indicate that all executable sections are compatible with IBT when ENDBR instruction starts each valid target where an indirect branch instruction can land. Linker sets GNU_PROPERTY_X86_FEATURE_1_IBT on output only if it is set on all relocatable inputs. On an IBT capable processor, the following steps should be taken: 1. When loading an executable without an interpreter, enable IBT and lock IBT if GNU_PROPERTY_X86_FEATURE_1_IBT is set on the executable. 2. When loading an executable with an interpreter, enable IBT if GNU_PROPERTY_X86_FEATURE_1_IBT is set on the interpreter. a. If GNU_PROPERTY_X86_FEATURE_1_IBT isn't set on the executable, disable IBT. b. Lock IBT. 3. If IBT is enabled, when loading a shared object without GNU_PROPERTY_X86_FEATURE_1_IBT: a. If legacy interwork is allowed, then mark all pages in executable PT_LOAD segments in legacy code page bitmap. Failure of legacy code page bitmap allocation causes an error. b. If legacy interwork isn't allowed, it causes an error. GNU_PROPERTY_X86_FEATURE_1_SHSTK is added to GNU program property to indicate that all executable sections are compatible with SHSTK where return address popped from shadow stack always matches return address popped from normal stack. Linker sets GNU_PROPERTY_X86_FEATURE_1_SHSTK on output only if it is set on all relocatable inputs. On a SHSTK capable processor, the following steps should be taken: 1. When loading an executable without an interpreter, enable SHSTK if GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on the executable. 2. When loading an executable with an interpreter, enable SHSTK if GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on interpreter. a. If GNU_PROPERTY_X86_FEATURE_1_SHSTK isn't set on the executable or any shared objects loaded via the DT_NEEDED tag, disable SHSTK. b. Otherwise lock SHSTK. 3. After SHSTK is enabled, it is an error to load a shared object without GNU_PROPERTY_X86_FEATURE_1_SHSTK. To enable CET support in glibc, --enable-cet is required to configure glibc. When CET is enabled, both compiler and assembler must support CET. Otherwise, it is a configure-time error. To support CET run-time control, 1. _dl_x86_feature_1 is added to the writable ld.so namespace to indicate if IBT or SHSTK are enabled at run-time. It should be initialized by init_cpu_features. 2. For dynamic executables: a. A l_cet field is added to struct link_map to indicate if IBT or SHSTK is enabled in an ELF module. _dl_process_pt_note or _rtld_process_pt_note is called to process PT_NOTE segment for GNU program property and set l_cet. b. _dl_open_check is added to check IBT and SHSTK compatibilty when dlopening a shared object. 3. Replace i386 _dl_runtime_resolve and _dl_runtime_profile with _dl_runtime_resolve_shstk and _dl_runtime_profile_shstk, respectively if SHSTK is enabled. CET run-time control can be changed via GLIBC_TUNABLES with $ export GLIBC_TUNABLES=glibc.tune.x86_shstk=[permissive|on|off] $ export GLIBC_TUNABLES=glibc.tune.x86_ibt=[permissive|on|off] 1. permissive: SHSTK is disabled when dlopening a legacy ELF module. 2. on: IBT or SHSTK are always enabled, regardless if there are IBT or SHSTK bits in GNU program property. 3. off: IBT or SHSTK are always disabled, regardless if there are IBT or SHSTK bits in GNU program property. from CET-enabled GCC is automatically included by assembly codes to add GNU_PROPERTY_X86_FEATURE_1_IBT and GNU_PROPERTY_X86_FEATURE_1_SHSTK to GNU program property. _CET_ENDBR is added at the entrance of all assembly functions whose address may be taken. _CET_NOTRACK is used to insert NOTRACK prefix with indirect jump table to support IBT. It is defined as notrack when _CET_NOTRACK is defined in . [BZ #21598] * configure.ac: Add --enable-cet. * configure: Regenerated. * elf/Makefille (all-built-dso): Add a comment. * elf/dl-load.c (filebuf): Moved before "dynamic-link.h". Include . (_dl_map_object_from_fd): Call _dl_process_pt_note on PT_NOTE segment. * elf/dl-open.c: Include . (dl_open_worker): Call _dl_open_check. * elf/rtld.c: Include . (dl_main): Call _rtld_process_pt_note on PT_NOTE segment. Call _rtld_main_check. * sysdeps/generic/dl-prop.h: New file. * sysdeps/i386/dl-cet.c: Likewise. * sysdeps/unix/sysv/linux/x86/cpu-features.c: Likewise. * sysdeps/unix/sysv/linux/x86/dl-cet.h: Likewise. * sysdeps/x86/cet-tunables.h: Likewise. * sysdeps/x86/check-cet.awk: Likewise. * sysdeps/x86/configure: Likewise. * sysdeps/x86/configure.ac: Likewise. * sysdeps/x86/dl-cet.c: Likewise. * sysdeps/x86/dl-procruntime.c: Likewise. * sysdeps/x86/dl-prop.h: Likewise. * sysdeps/x86/libc-start.h: Likewise. * sysdeps/x86/link_map.h: Likewise. * sysdeps/i386/dl-trampoline.S (_dl_runtime_resolve): Add _CET_ENDBR. (_dl_runtime_profile): Likewise. (_dl_runtime_resolve_shstk): New. (_dl_runtime_profile_shstk): Likewise. * sysdeps/linux/x86/Makefile (sysdep-dl-routines): Add dl-cet if CET is enabled. (CFLAGS-.o): Add -fcf-protection if CET is enabled. (CFLAGS-.os): Likewise. (CFLAGS-.op): Likewise. (CFLAGS-.oS): Likewise. (asm-CPPFLAGS): Add -fcf-protection -include cet.h if CET is enabled. (tests-special): Add $(objpfx)check-cet.out. (cet-built-dso): New. (+$(cet-built-dso:=.note)): Likewise. (common-generated): Add $(cet-built-dso:$(common-objpfx)%=%.note). ($(objpfx)check-cet.out): New. (generated): Add check-cet.out. * sysdeps/x86/cpu-features.c: Include and . (TUNABLE_CALLBACK (set_x86_ibt)): New prototype. (TUNABLE_CALLBACK (set_x86_shstk)): Likewise. (init_cpu_features): Call get_cet_status to check CET status and update dl_x86_feature_1 with CET status. Call TUNABLE_CALLBACK (set_x86_ibt) and TUNABLE_CALLBACK (set_x86_shstk). Disable and lock CET in libc.a. * sysdeps/x86/cpu-tunables.c: Include . (TUNABLE_CALLBACK (set_x86_ibt)): New function. (TUNABLE_CALLBACK (set_x86_shstk)): Likewise. * sysdeps/x86/sysdep.h (_CET_NOTRACK): New. (_CET_ENDBR): Define if not defined. (ENTRY): Add _CET_ENDBR. * sysdeps/x86/dl-tunables.list (glibc.tune): Add x86_ibt and x86_shstk. * sysdeps/x86_64/dl-trampoline.h (_dl_runtime_resolve): Add _CET_ENDBR. (_dl_runtime_profile): Likewise. --- configure | 11 + configure.ac | 6 + elf/Makefile | 2 + elf/dl-load.c | 60 ++-- elf/dl-open.c | 3 + elf/rtld.c | 9 + sysdeps/generic/dl-prop.h | 47 +++ sysdeps/i386/dl-cet.c | 67 +++++ sysdeps/i386/dl-trampoline.S | 72 +++++ sysdeps/unix/sysv/linux/x86/cpu-features.c | 38 +++ sysdeps/unix/sysv/linux/x86/dl-cet.h | 34 +++ sysdeps/x86/Makefile | 42 +++ sysdeps/x86/cet-tunables.h | 29 ++ sysdeps/x86/check-cet.awk | 53 ++++ sysdeps/x86/configure | 69 +++++ sysdeps/x86/configure.ac | 46 +++ sysdeps/x86/cpu-features.c | 60 ++++ sysdeps/x86/cpu-tunables.c | 48 +++ sysdeps/x86/dl-cet.c | 335 +++++++++++++++++++++ sysdeps/x86/dl-procruntime.c | 68 +++++ sysdeps/x86/dl-prop.h | 153 ++++++++++ sysdeps/x86/dl-tunables.list | 6 + sysdeps/x86/libc-start.h | 25 ++ sysdeps/x86/link_map.h | 26 ++ sysdeps/x86/sysdep.h | 8 + sysdeps/x86_64/dl-trampoline.h | 2 + 26 files changed, 1294 insertions(+), 25 deletions(-) create mode 100644 sysdeps/generic/dl-prop.h create mode 100644 sysdeps/i386/dl-cet.c create mode 100644 sysdeps/unix/sysv/linux/x86/cpu-features.c create mode 100644 sysdeps/unix/sysv/linux/x86/dl-cet.h create mode 100644 sysdeps/x86/cet-tunables.h create mode 100644 sysdeps/x86/check-cet.awk create mode 100644 sysdeps/x86/configure create mode 100644 sysdeps/x86/configure.ac create mode 100644 sysdeps/x86/dl-cet.c create mode 100644 sysdeps/x86/dl-procruntime.c create mode 100644 sysdeps/x86/dl-prop.h create mode 100644 sysdeps/x86/libc-start.h create mode 100644 sysdeps/x86/link_map.h diff --git a/configure b/configure index eac7f292b4..fde57d63fe 100755 --- a/configure +++ b/configure @@ -790,6 +790,7 @@ enable_nscd enable_pt_chown enable_tunables enable_mathvec +enable_cet with_cpu ' ac_precious_vars='build_alias @@ -1465,6 +1466,8 @@ Optional Features: 'no' and 'valstring' --enable-mathvec Enable building and installing mathvec [default depends on architecture] + --enable-cet enable Intel Control-flow Enforcement Technology + (CET), x86 only Optional Packages: --with-PACKAGE[=ARG] use PACKAGE [ARG=yes] @@ -3759,6 +3762,14 @@ else fi +# Check whether --enable-cet was given. +if test "${enable_cet+set}" = set; then : + enableval=$enable_cet; enable_cet=$enableval +else + enable_cet=no +fi + + # We keep the original values in `$config_*' and never modify them, so we # can write them unchanged into config.make. Everything else uses # $machine, $vendor, and $os, and changes them whenever convenient. diff --git a/configure.ac b/configure.ac index f41ed6decb..014e09a5d5 100644 --- a/configure.ac +++ b/configure.ac @@ -464,6 +464,12 @@ AC_ARG_ENABLE([mathvec], [build_mathvec=$enableval], [build_mathvec=notset]) +AC_ARG_ENABLE([cet], + AC_HELP_STRING([--enable-cet], + [enable Intel Control-flow Enforcement Technology (CET), x86 only]), + [enable_cet=$enableval], + [enable_cet=no]) + # We keep the original values in `$config_*' and never modify them, so we # can write them unchanged into config.make. Everything else uses # $machine, $vendor, and $os, and changes them whenever convenient. diff --git a/elf/Makefile b/elf/Makefile index 41cc3681be..84107f6dbb 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -1058,6 +1058,8 @@ $(objpfx)tst-piemod1.so: $(libsupport) $(objpfx)tst-pie1: $(objpfx)tst-piemod1.so ifeq (yes,$(build-shared)) +# NB: Please keep cet-built-dso in sysdeps/x86/Makefile in sync with +# all-built-dso here. all-built-dso := $(common-objpfx)elf/ld.so $(common-objpfx)libc.so \ $(filter-out $(common-objpfx)linkobj/libc.so, \ $(sort $(wildcard $(addprefix $(common-objpfx), \ diff --git a/elf/dl-load.c b/elf/dl-load.c index 09185ab68d..c51e4b3718 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -30,6 +30,32 @@ #include #include #include + +/* Type for the buffer we put the ELF header and hopefully the program + header. This buffer does not really have to be too large. In most + cases the program header follows the ELF header directly. If this + is not the case all bets are off and we can make the header + arbitrarily large and still won't get it read. This means the only + question is how large are the ELF and program header combined. The + ELF header 32-bit files is 52 bytes long and in 64-bit files is 64 + bytes long. Each program header entry is again 32 and 56 bytes + long respectively. I.e., even with a file which has 10 program + header entries we only have to read 372B/624B respectively. Add to + this a bit of margin for program notes and reading 512B and 832B + for 32-bit and 64-bit files respecitvely is enough. If this + heuristic should really fail for some file the code in + `_dl_map_object_from_fd' knows how to recover. */ +struct filebuf +{ + ssize_t len; +#if __WORDSIZE == 32 +# define FILEBUF_SIZE 512 +#else +# define FILEBUF_SIZE 832 +#endif + char buf[FILEBUF_SIZE] __attribute__ ((aligned (__alignof (ElfW(Ehdr))))); +}; + #include "dynamic-link.h" #include #include @@ -44,6 +70,7 @@ #include #include #include +#include #include #include @@ -69,31 +96,6 @@ int __stack_prot attribute_hidden attribute_relro #endif -/* Type for the buffer we put the ELF header and hopefully the program - header. This buffer does not really have to be too large. In most - cases the program header follows the ELF header directly. If this - is not the case all bets are off and we can make the header - arbitrarily large and still won't get it read. This means the only - question is how large are the ELF and program header combined. The - ELF header 32-bit files is 52 bytes long and in 64-bit files is 64 - bytes long. Each program header entry is again 32 and 56 bytes - long respectively. I.e., even with a file which has 10 program - header entries we only have to read 372B/624B respectively. Add to - this a bit of margin for program notes and reading 512B and 832B - for 32-bit and 64-bit files respecitvely is enough. If this - heuristic should really fail for some file the code in - `_dl_map_object_from_fd' knows how to recover. */ -struct filebuf -{ - ssize_t len; -#if __WORDSIZE == 32 -# define FILEBUF_SIZE 512 -#else -# define FILEBUF_SIZE 832 -#endif - char buf[FILEBUF_SIZE] __attribute__ ((aligned (__alignof (ElfW(Ehdr))))); -}; - /* This is the decomposed LD_LIBRARY_PATH search path. */ static struct r_search_path_struct env_path_list attribute_relro; @@ -1152,6 +1154,14 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, l->l_relro_addr = ph->p_vaddr; l->l_relro_size = ph->p_memsz; break; + + case PT_NOTE: + if (_dl_process_pt_note (l, ph, fd, fbp)) + { + errstring = N_("cannot process note segment"); + goto call_lose; + } + break; } if (__glibc_unlikely (nloadcmds == 0)) diff --git a/elf/dl-open.c b/elf/dl-open.c index 9dde4acfbc..f6c8ef1043 100644 --- a/elf/dl-open.c +++ b/elf/dl-open.c @@ -35,6 +35,7 @@ #include #include +#include /* We must be careful not to leave us in an inconsistent state. Thus we @@ -291,6 +292,8 @@ dl_open_worker (void *a) _dl_debug_state (); LIBC_PROBE (map_complete, 3, args->nsid, r, new); + _dl_open_check (new); + /* Print scope information. */ if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_SCOPES)) _dl_show_scope (new, 0); diff --git a/elf/rtld.c b/elf/rtld.c index 8c732adb68..1b0c74739f 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -38,6 +38,7 @@ #include #include #include +#include #include #include #include @@ -1241,6 +1242,12 @@ of this helper program; chances are you did not intend to run this program.\n\ main_map->l_relro_addr = ph->p_vaddr; main_map->l_relro_size = ph->p_memsz; break; + + case PT_NOTE: + if (_rtld_process_pt_note (main_map, ph)) + _dl_error_printf ("\ +ERROR: '%s': cannot process note segment.\n", _dl_argv[0]); + break; } /* Adjust the address of the TLS initialization image in case @@ -2110,6 +2117,8 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n", _dl_show_scope (l, 0); } + _rtld_main_check (main_map, _dl_argv[0]); + if (prelinked) { if (main_map->l_info [ADDRIDX (DT_GNU_CONFLICT)] != NULL) diff --git a/sysdeps/generic/dl-prop.h b/sysdeps/generic/dl-prop.h new file mode 100644 index 0000000000..e5fe5d23aa --- /dev/null +++ b/sysdeps/generic/dl-prop.h @@ -0,0 +1,47 @@ +/* Support for GNU properties. Generic version. + Copyright (C) 2018 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#ifndef _DL_PROP_H +#define _DL_PROP_H + +static inline void __attribute__ ((always_inline)) +_rtld_main_check (struct link_map *m, const char *program) +{ +} + +static inline void __attribute__ ((always_inline)) +_dl_open_check (struct link_map *m) +{ +} + +#ifdef FILEBUF_SIZE +static inline int __attribute__ ((always_inline)) +_dl_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph, + int fd, struct filebuf *fbp) +{ + return 0; +} +#endif + +static inline int __attribute__ ((always_inline)) +_rtld_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph) +{ + return 0; +} + +#endif /* _DL_PROP_H */ diff --git a/sysdeps/i386/dl-cet.c b/sysdeps/i386/dl-cet.c new file mode 100644 index 0000000000..5d9a4e8d51 --- /dev/null +++ b/sysdeps/i386/dl-cet.c @@ -0,0 +1,67 @@ +/* Linux/i386 CET initializers function. + Copyright (C) 2018 Free Software Foundation, Inc. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + + +#define LINKAGE static inline +#define _dl_cet_check cet_check +#include +#undef _dl_cet_check + +#ifdef SHARED +void +_dl_cet_check (struct link_map *main_map, const char *program) +{ + cet_check (main_map, program); + + if ((GL(dl_x86_feature_1)[0] & GNU_PROPERTY_X86_FEATURE_1_SHSTK)) + { + /* Replace _dl_runtime_resolve and _dl_runtime_profile with + _dl_runtime_resolve_shstk and _dl_runtime_profile_shstk, + respectively if SHSTK is enabled. */ + extern void _dl_runtime_resolve (Elf32_Word) attribute_hidden; + extern void _dl_runtime_resolve_shstk (Elf32_Word) attribute_hidden; + extern void _dl_runtime_profile (Elf32_Word) attribute_hidden; + extern void _dl_runtime_profile_shstk (Elf32_Word) attribute_hidden; + unsigned int i; + struct link_map *l; + Elf32_Addr *got; + + if (main_map->l_info[DT_JMPREL]) + { + got = (Elf32_Addr *) D_PTR (main_map, l_info[DT_PLTGOT]); + if (got[2] == (Elf32_Addr) &_dl_runtime_resolve) + got[2] = (Elf32_Addr) &_dl_runtime_resolve_shstk; + else if (got[2] == (Elf32_Addr) &_dl_runtime_profile) + got[2] = (Elf32_Addr) &_dl_runtime_profile_shstk; + } + + i = main_map->l_searchlist.r_nlist; + while (i-- > 0) + { + l = main_map->l_initfini[i]; + if (l->l_info[DT_JMPREL]) + { + got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]); + if (got[2] == (Elf32_Addr) &_dl_runtime_resolve) + got[2] = (Elf32_Addr) &_dl_runtime_resolve_shstk; + else if (got[2] == (Elf32_Addr) &_dl_runtime_profile) + got[2] = (Elf32_Addr) &_dl_runtime_profile_shstk; + } + } + } +} +#endif diff --git a/sysdeps/i386/dl-trampoline.S b/sysdeps/i386/dl-trampoline.S index 8bf86f8fd9..6dc0319216 100644 --- a/sysdeps/i386/dl-trampoline.S +++ b/sysdeps/i386/dl-trampoline.S @@ -32,6 +32,7 @@ .align 16 _dl_runtime_resolve: cfi_adjust_cfa_offset (8) + _CET_ENDBR pushl %eax # Preserve registers otherwise clobbered. cfi_adjust_cfa_offset (4) pushl %ecx @@ -50,14 +51,85 @@ _dl_runtime_resolve: cfi_endproc .size _dl_runtime_resolve, .-_dl_runtime_resolve +# The SHSTK compatible version. + .text + .globl _dl_runtime_resolve_shstk + .type _dl_runtime_resolve_shstk, @function + cfi_startproc + .align 16 +_dl_runtime_resolve_shstk: + cfi_adjust_cfa_offset (8) + _CET_ENDBR + pushl %eax # Preserve registers otherwise clobbered. + cfi_adjust_cfa_offset (4) + pushl %edx + cfi_adjust_cfa_offset (4) + movl 12(%esp), %edx # Copy args pushed by PLT in register. Note + movl 8(%esp), %eax # that `fixup' takes its parameters in regs. + call _dl_fixup # Call resolver. + movl (%esp), %edx # Get register content back. + movl %eax, %ecx # Store the function address. + movl 4(%esp), %eax # Get register content back. + addl $16, %esp # Adjust stack: PLT1 + PLT2 + %eax + %edx + cfi_adjust_cfa_offset (-16) + jmp *%ecx # Jump to function address. + cfi_endproc + .size _dl_runtime_resolve_shstk, .-_dl_runtime_resolve_shstk #ifndef PROF +# The SHSTK compatible version. + .globl _dl_runtime_profile_shstk + .type _dl_runtime_profile_shstk, @function + cfi_startproc + .align 16 +_dl_runtime_profile_shstk: + cfi_adjust_cfa_offset (8) + _CET_ENDBR + pushl %esp + cfi_adjust_cfa_offset (4) + addl $8, (%esp) # Account for the pushed PLT data + pushl %ebp + cfi_adjust_cfa_offset (4) + pushl %eax # Preserve registers otherwise clobbered. + cfi_adjust_cfa_offset (4) + pushl %ecx + cfi_adjust_cfa_offset (4) + pushl %edx + cfi_adjust_cfa_offset (4) + movl %esp, %ecx + subl $8, %esp + cfi_adjust_cfa_offset (8) + movl $-1, 4(%esp) + leal 4(%esp), %edx + movl %edx, (%esp) + pushl %ecx # Address of the register structure + cfi_adjust_cfa_offset (4) + movl 40(%esp), %ecx # Load return address + movl 36(%esp), %edx # Copy args pushed by PLT in register. Note + movl 32(%esp), %eax # that `fixup' takes its parameters in regs. + call _dl_profile_fixup # Call resolver. + cfi_adjust_cfa_offset (-8) + movl (%esp), %edx + testl %edx, %edx + jns 1f + movl 4(%esp), %edx # Get register content back. + movl %eax, %ecx # Store the function address. + movl 12(%esp), %eax # Get register content back. + # Adjust stack: PLT1 + PLT2 + %esp + %ebp + %eax + %ecx + %edx + # + free. + addl $32, %esp + cfi_adjust_cfa_offset (-32) + jmp *%ecx # Jump to function address. + cfi_endproc + .size _dl_runtime_profile_shstk, .-_dl_runtime_profile_shstk + .globl _dl_runtime_profile .type _dl_runtime_profile, @function cfi_startproc .align 16 _dl_runtime_profile: cfi_adjust_cfa_offset (8) + _CET_ENDBR pushl %esp cfi_adjust_cfa_offset (4) addl $8, (%esp) # Account for the pushed PLT data diff --git a/sysdeps/unix/sysv/linux/x86/cpu-features.c b/sysdeps/unix/sysv/linux/x86/cpu-features.c new file mode 100644 index 0000000000..0045f979da --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/cpu-features.c @@ -0,0 +1,38 @@ +/* Initialize CPU feature data for Linux/x86. + This file is part of the GNU C Library. + Copyright (C) 2018 Free Software Foundation, Inc. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#ifdef __CET__ +static inline int __attribute__ ((always_inline)) +get_cet_status (void) +{ + return 0; +} + +# ifndef SHARED +static inline void +x86_setup_tls (void) +{ + __libc_setup_tls (); + THREAD_SETMEM (THREAD_SELF, header.feature_1, GL(dl_x86_feature_1)[0]); +} + +# define ARCH_SETUP_TLS() x86_setup_tls () +# endif +#endif + +#include diff --git a/sysdeps/unix/sysv/linux/x86/dl-cet.h b/sysdeps/unix/sysv/linux/x86/dl-cet.h new file mode 100644 index 0000000000..9903bbe41f --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/dl-cet.h @@ -0,0 +1,34 @@ +/* Linux/x86 CET initializers function. + Copyright (C) 2018 Free Software Foundation, Inc. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +static inline int __attribute__ ((always_inline)) +dl_cet_allocate_legacy_bitmap (unsigned long *legacy_bitmap) +{ + return -1; +} + +static inline int __attribute__ ((always_inline)) +dl_cet_disable_cet (unsigned int cet_feature) +{ + return -1; +} + +static inline int __attribute__ ((always_inline)) +dl_cet_lock_cet (void) +{ + return -1; +} diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile index 65292f4032..e9b2d0b35d 100644 --- a/sysdeps/x86/Makefile +++ b/sysdeps/x86/Makefile @@ -13,3 +13,45 @@ ifeq ($(subdir),setjmp) gen-as-const-headers += jmp_buf-ssp.sym sysdep_routines += __longjmp_cancel endif + +ifeq ($(enable-cet),yes) +ifeq ($(subdir),elf) +sysdep-dl-routines += dl-cet +endif + +# Add -fcf-protection to CFLAGS when CET is enabled. +CFLAGS-.o += -fcf-protection +CFLAGS-.os += -fcf-protection +CFLAGS-.op += -fcf-protection +CFLAGS-.oS += -fcf-protection + +# Compile assembly codes with when CET is enabled. +asm-CPPFLAGS += -fcf-protection -include cet.h + +ifeq ($(subdir),elf) +ifeq (yes,$(build-shared)) +tests-special += $(objpfx)check-cet.out +endif + +# FIXME: Can't use all-built-dso in elf/Makefile since this file is +# processed before elf/Makefile. Duplicate it here. +cet-built-dso := $(common-objpfx)elf/ld.so $(common-objpfx)libc.so \ + $(filter-out $(common-objpfx)linkobj/libc.so, \ + $(sort $(wildcard $(addprefix $(common-objpfx), \ + */lib*.so \ + iconvdata/*.so)))) + +$(cet-built-dso:=.note): %.note: % + @rm -f $@T + LC_ALL=C $(READELF) -n $< > $@T + test -s $@T + mv -f $@T $@ +common-generated += $(cet-built-dso:$(common-objpfx)%=%.note) + +$(objpfx)check-cet.out: $(..)sysdeps/x86/check-cet.awk \ + $(cet-built-dso:=.note) + LC_ALL=C $(AWK) -f $^ > $@; \ + $(evaluate-test) +generated += check-cet.out +endif +endif diff --git a/sysdeps/x86/cet-tunables.h b/sysdeps/x86/cet-tunables.h new file mode 100644 index 0000000000..ca023053ee --- /dev/null +++ b/sysdeps/x86/cet-tunables.h @@ -0,0 +1,29 @@ +/* x86 CET tuning. + This file is part of the GNU C Library. + Copyright (C) 2018 Free Software Foundation, Inc. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +/* Valid control values: + 0: Enable CET features based on ELF property note. + 1: Always disable CET features. + 2: Always enable CET features. + 3: Enable CET features permissively. + */ +#define CET_ELF_PROPERTY 0 +#define CET_ALWAYS_OFF 1 +#define CET_ALWAYS_ON 2 +#define CET_PERMISSIVE 3 +#define CET_MAX CET_PERMISSIVE diff --git a/sysdeps/x86/check-cet.awk b/sysdeps/x86/check-cet.awk new file mode 100644 index 0000000000..380d998caf --- /dev/null +++ b/sysdeps/x86/check-cet.awk @@ -0,0 +1,53 @@ +# Verify that all shared objects contain the CET property. +# Copyright (C) 2018 Free Software Foundation, Inc. +# This file is part of the GNU C Library. +# +# The GNU C Library is free software; you can redistribute it and/or +# modify it under the terms of the GNU Lesser General Public +# License as published by the Free Software Foundation; either +# version 2.1 of the License, or (at your option) any later version. +# +# The GNU C Library is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public +# License along with the GNU C Library; if not, see +# . + +# This awk script expects to get command-line files that are each +# the output of 'readelf -n' on a single shared object. +# It exits successfully (0) if all of them contained the CET property. +# It fails (1) if any didn't contain the CET property +# It fails (2) if the input did not take the expected form. + +BEGIN { result = cet = sanity = 0 } + +function check_one(name) { + if (!sanity) { + print name ": *** input did not look like readelf -n output"; + result = 2; + } else if (cet) { + print name ": OK"; + } else { + print name ": *** no CET property found"; + result = result ? result : 1; + } + + cet = sanity = 0; +} + +FILENAME != lastfile { + if (lastfile) + check_one(lastfile); + lastfile = FILENAME; +} + +index ($0, "Displaying notes") != 0 { sanity = 1 } +index ($0, "IBT") != 0 && index ($0, "SHSTK") != 0 { cet = 1 } + +END { + check_one(lastfile); + exit(result); +} diff --git a/sysdeps/x86/configure b/sysdeps/x86/configure new file mode 100644 index 0000000000..b1ff281249 --- /dev/null +++ b/sysdeps/x86/configure @@ -0,0 +1,69 @@ +# This file is generated from configure.ac by Autoconf. DO NOT EDIT! + # Local configure fragment for sysdeps/x86. + +if test x"$enable_cet" = xyes; then + # Check if CET can be enabled. + { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether CET can be enabled" >&5 +$as_echo_n "checking whether CET can be enabled... " >&6; } +if ${libc_cv_x86_cet_available+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.c <&5 + (eval $ac_try) 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; }; }; then + libc_cv_x86_cet_available=yes + else + libc_cv_x86_cet_available=no + fi + rm -rf conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_x86_cet_available" >&5 +$as_echo "$libc_cv_x86_cet_available" >&6; } + if test $libc_cv_x86_cet_available = yes; then + enable_cet=yes + else + if test x"$enable_cet" = xdefault; then + enable_cet=no + else + as_fn_error $? "$CC doesn't support CET" "$LINENO" 5 + fi + fi +fi +if test $enable_cet = yes; then + # Check if assembler supports CET. + { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $AS supports CET" >&5 +$as_echo_n "checking whether $AS supports CET... " >&6; } +if ${libc_cv_x86_cet_as+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.s <&5 + (eval $ac_try) 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; }; }; then + libc_cv_x86_cet_as=yes + else + libc_cv_x86_cet_as=no + fi + rm -rf conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_x86_cet_as" >&5 +$as_echo "$libc_cv_x86_cet_as" >&6; } + if test $libc_cv_x86_cet_as = no; then + as_fn_error $? "$AS doesn't support CET" "$LINENO" 5 + fi +fi +config_vars="$config_vars +enable-cet = $enable_cet" diff --git a/sysdeps/x86/configure.ac b/sysdeps/x86/configure.ac new file mode 100644 index 0000000000..a909b073af --- /dev/null +++ b/sysdeps/x86/configure.ac @@ -0,0 +1,46 @@ +GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory. +# Local configure fragment for sysdeps/x86. + +if test x"$enable_cet" = xyes; then + # Check if CET can be enabled. + AC_CACHE_CHECK(whether CET can be enabled, + libc_cv_x86_cet_available, [dnl +cat > conftest.c <&AS_MESSAGE_LOG_FD); then + libc_cv_x86_cet_available=yes + else + libc_cv_x86_cet_available=no + fi + rm -rf conftest*]) + if test $libc_cv_x86_cet_available = yes; then + enable_cet=yes + else + if test x"$enable_cet" = xdefault; then + enable_cet=no + else + AC_MSG_ERROR([$CC doesn't support CET]) + fi + fi +fi +if test $enable_cet = yes; then + # Check if assembler supports CET. + AC_CACHE_CHECK(whether $AS supports CET, + libc_cv_x86_cet_as, [dnl +cat > conftest.s <&AS_MESSAGE_LOG_FD); then + libc_cv_x86_cet_as=yes + else + libc_cv_x86_cet_as=no + fi + rm -rf conftest*]) + if test $libc_cv_x86_cet_as = no; then + AC_MSG_ERROR([$AS doesn't support CET]) + fi +fi +LIBC_CONFIG_VAR([enable-cet], [$enable_cet]) diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c index d41ebde823..f52e28e04b 100644 --- a/sysdeps/x86/cpu-features.c +++ b/sysdeps/x86/cpu-features.c @@ -28,6 +28,15 @@ extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *) attribute_hidden; + +# ifdef __CET__ +# include +# include +extern void TUNABLE_CALLBACK (set_x86_ibt) (tunable_val_t *) + attribute_hidden; +extern void TUNABLE_CALLBACK (set_x86_shstk) (tunable_val_t *) + attribute_hidden; +# endif #endif static void @@ -449,4 +458,55 @@ no_cpuid: else if (CPU_FEATURES_ARCH_P (cpu_features, I586)) GLRO(dl_platform) = "i586"; #endif + +#ifdef __CET__ +# if HAVE_TUNABLES + TUNABLE_GET (x86_ibt, tunable_val_t *, + TUNABLE_CALLBACK (set_x86_ibt)); + TUNABLE_GET (x86_shstk, tunable_val_t *, + TUNABLE_CALLBACK (set_x86_shstk)); +# endif + + /* Check CET status. */ + unsigned int cet_status = get_cet_status (); + + if (cet_status) + { + GL(dl_x86_feature_1)[0] = cet_status; + +# ifndef SHARED + /* Check if IBT and SHSTK are enabled by kernel. */ + if ((cet_status & GNU_PROPERTY_X86_FEATURE_1_IBT) + || (cet_status & GNU_PROPERTY_X86_FEATURE_1_SHSTK)) + { + /* Disable IBT and/or SHSTK if they are enabled by kernel, but + disabled by environment variable: + + GLIBC_TUNABLES=glibc.tune.hwcaps=-IBT,-SHSTK + */ + unsigned int cet_feature = 0; + if (!HAS_CPU_FEATURE (IBT)) + cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT; + if (!HAS_CPU_FEATURE (SHSTK)) + cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK; + + if (cet_feature) + { + int res = dl_cet_disable_cet (cet_feature); + + /* Clear the disabled bits in dl_x86_feature_1. */ + if (res == 0) + GL(dl_x86_feature_1)[0] &= ~cet_feature; + } + + /* Lock CET if IBT or SHSTK is enabled in executable. Don't + lock CET if SHSTK is enabled permissively. */ + if (((GL(dl_x86_feature_1)[1] >> CET_MAX) + & ((1 << CET_MAX) - 1)) + != CET_PERMISSIVE) + dl_cet_lock_cet (); + } +# endif + } +#endif } diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c index af761dcbbc..a5c0153348 100644 --- a/sysdeps/x86/cpu-tunables.c +++ b/sysdeps/x86/cpu-tunables.c @@ -334,4 +334,52 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp) } while (*p != '\0'); } + +# ifdef __CET__ +# include + +attribute_hidden +void +TUNABLE_CALLBACK (set_x86_ibt) (tunable_val_t *valp) +{ + if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0) + { + GL(dl_x86_feature_1)[1] &= ~((1 << CET_MAX) - 1); + GL(dl_x86_feature_1)[1] |= CET_ALWAYS_ON; + } + else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0) + { + GL(dl_x86_feature_1)[1] &= ~((1 << CET_MAX) - 1); + GL(dl_x86_feature_1)[1] |= CET_ALWAYS_OFF; + } + else if (DEFAULT_MEMCMP (valp->strval, "permissive", + sizeof ("permissive")) == 0) + { + GL(dl_x86_feature_1)[1] &= ~((1 << CET_MAX) - 1); + GL(dl_x86_feature_1)[1] |= CET_PERMISSIVE; + } +} + +attribute_hidden +void +TUNABLE_CALLBACK (set_x86_shstk) (tunable_val_t *valp) +{ + if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0) + { + GL(dl_x86_feature_1)[1] &= ~(((1 << CET_MAX) - 1) << CET_MAX); + GL(dl_x86_feature_1)[1] |= (CET_ALWAYS_ON << CET_MAX); + } + else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0) + { + GL(dl_x86_feature_1)[1] &= ~(((1 << CET_MAX) - 1) << CET_MAX); + GL(dl_x86_feature_1)[1] |= (CET_ALWAYS_OFF << CET_MAX); + } + else if (DEFAULT_MEMCMP (valp->strval, "permissive", + sizeof ("permissive")) == 0) + { + GL(dl_x86_feature_1)[1] &= ~(((1 << CET_MAX) - 1) << CET_MAX); + GL(dl_x86_feature_1)[1] |= (CET_PERMISSIVE << CET_MAX); + } +} +# endif #endif diff --git a/sysdeps/x86/dl-cet.c b/sysdeps/x86/dl-cet.c new file mode 100644 index 0000000000..5018e4560d --- /dev/null +++ b/sysdeps/x86/dl-cet.c @@ -0,0 +1,335 @@ +/* x86 CET initializers function. + Copyright (C) 2018 Free Software Foundation, Inc. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include +#include +#include +#include +#include + +static int +dl_cet_mark_legacy_region (struct link_map *l) +{ + /* Mark PT_LOAD segments with PF_X in legacy code page bitmap. */ + size_t i, phnum = l->l_phnum; + const ElfW(Phdr) *phdr = l->l_phdr; +#ifdef __x86_64__ + typedef unsigned long long word_t; +#else + typedef unsigned long word_t; +#endif + unsigned int bits_to_set; + word_t mask_to_set; +#define BITS_PER_WORD (sizeof (word_t) * 8) +#define BITMAP_FIRST_WORD_MASK(start) \ + (~((word_t) 0) << ((start) & (BITS_PER_WORD - 1))) +#define BITMAP_LAST_WORD_MASK(nbits) \ + (~((word_t) 0) >> (-(nbits) & (BITS_PER_WORD - 1))) + + word_t *bitmap = (word_t *) GL(dl_x86_legacy_bitmap)[0]; + word_t bitmap_size = GL(dl_x86_legacy_bitmap)[1]; + word_t *p; + size_t page_size = GLRO(dl_pagesize); + + for (i = 0; i < phnum; i++) + if (phdr[i].p_type == PT_LOAD && (phdr[i].p_flags & PF_X)) + { + /* One bit in legacy bitmap represents a page. */ + ElfW(Addr) start = (phdr[i].p_vaddr + l->l_addr) / page_size; + ElfW(Addr) len = (phdr[i].p_memsz + page_size - 1) / page_size; + ElfW(Addr) end = start + len; + + if ((end / 8) > bitmap_size) + return -EFAULT; + + p = bitmap + (start / BITS_PER_WORD); + bits_to_set = BITS_PER_WORD - (start % BITS_PER_WORD); + mask_to_set = BITMAP_FIRST_WORD_MASK (start); + + while (len >= bits_to_set) + { + *p |= mask_to_set; + len -= bits_to_set; + bits_to_set = BITS_PER_WORD; + mask_to_set = ~((word_t) 0); + p++; + } + if (len) + { + mask_to_set &= BITMAP_LAST_WORD_MASK (end); + *p |= mask_to_set; + } + } + + return 0; +} + +/* Check if object M is compatible with CET. */ + +static void +dl_cet_check (struct link_map *m, const char *program) +{ + /* Check how IBT should be enabled. */ + unsigned int enable_ibt_type + = GL(dl_x86_feature_1)[1] & ((1 << CET_MAX) - 1); + /* Check how SHSTK should be enabled. */ + unsigned int enable_shstk_type + = ((GL(dl_x86_feature_1)[1] >> CET_MAX) & ((1 << CET_MAX) - 1)); + + /* No legacy object check if both IBT and SHSTK are always on. */ + if (enable_ibt_type == CET_ALWAYS_ON + && enable_shstk_type == CET_ALWAYS_ON) + return; + + /* Check if IBT is enabled by kernel. */ + bool ibt_enabled + = (GL(dl_x86_feature_1)[0] & GNU_PROPERTY_X86_FEATURE_1_IBT) != 0; + /* Check if SHSTK is enabled by kernel. */ + bool shstk_enabled + = (GL(dl_x86_feature_1)[0] & GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0; + + if (ibt_enabled || shstk_enabled) + { + struct link_map *l = NULL; + + /* Check if IBT and SHSTK are enabled in object. */ + bool enable_ibt = (ibt_enabled + && enable_ibt_type != CET_ALWAYS_OFF); + bool enable_shstk = (shstk_enabled + && enable_shstk_type != CET_ALWAYS_OFF); + if (program) + { + /* Enable IBT and SHSTK only if they are enabled in executable. + NB: IBT and SHSTK may be disabled by environment variable: + + GLIBC_TUNABLES=glibc.tune.hwcaps=-IBT,-SHSTK + */ + enable_ibt &= (HAS_CPU_FEATURE (IBT) + && (enable_ibt_type == CET_ALWAYS_ON + || (m->l_cet & lc_ibt) != 0)); + enable_shstk &= (HAS_CPU_FEATURE (SHSTK) + && (enable_shstk_type == CET_ALWAYS_ON + || (m->l_cet & lc_shstk) != 0)); + } + + /* ld.so is CET-enabled by kernel. But shared objects may not + support IBT nor SHSTK. */ + if (enable_ibt || enable_shstk) + { + int res; + unsigned int i; + unsigned int first_legacy, last_legacy; + bool need_legacy_bitmap = false; + + i = m->l_searchlist.r_nlist; + while (i-- > 0) + { + /* Check each shared object to see if IBT and SHSTK are + enabled. */ + l = m->l_initfini[i]; + + if (l->l_init_called) + continue; + +#ifdef SHARED + /* Skip CET check for ld.so since ld.so is CET-enabled. + CET will be disabled later if CET isn't enabled in + executable. */ + if (l == &GL(dl_rtld_map) + || l->l_real == &GL(dl_rtld_map) + || (program && l == m)) + continue; +#endif + + if (enable_ibt + && enable_ibt_type != CET_ALWAYS_ON + && !(l->l_cet & lc_ibt)) + { + /* Remember the first and last legacy objects. */ + if (!need_legacy_bitmap) + last_legacy = i; + first_legacy = i; + need_legacy_bitmap = true; + } + + /* SHSTK is enabled only if it is enabled in executable as + well as all shared objects. */ + enable_shstk &= (enable_shstk_type == CET_ALWAYS_ON + || (l->l_cet & lc_shstk) != 0); + } + + if (need_legacy_bitmap) + { + if (GL(dl_x86_legacy_bitmap)[0]) + { + /* Change legacy bitmap to writable. */ + if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0], + GL(dl_x86_legacy_bitmap)[1], + PROT_READ | PROT_WRITE) < 0) + { +mprotect_failure: + if (program) + _dl_fatal_printf ("%s: mprotect legacy bitmap failed\n", + l->l_name); + else + _dl_signal_error (EINVAL, l->l_name, "dlopen", + N_("mprotect legacy bitmap failed")); + } + } + else + { + /* Allocate legacy bitmap. */ + int res = dl_cet_allocate_legacy_bitmap + (GL(dl_x86_legacy_bitmap)); + if (res != 0) + { + if (program) + _dl_fatal_printf ("%s: legacy bitmap isn't available\n", + l->l_name); + else + _dl_signal_error (EINVAL, l->l_name, "dlopen", + N_("legacy bitmap isn't available")); + } + } + + /* Put legacy shared objects in legacy bitmap. */ + for (i = first_legacy; i <= last_legacy; i++) + { + l = m->l_initfini[i]; + + if (l->l_init_called || (l->l_cet & lc_ibt)) + continue; + +#ifdef SHARED + if (l == &GL(dl_rtld_map) + || l->l_real == &GL(dl_rtld_map) + || (program && l == m)) + continue; +#endif + + /* If IBT is enabled in executable and IBT isn't enabled + in this shard object, mark PT_LOAD segments with PF_X + in legacy code page bitmap. */ + res = dl_cet_mark_legacy_region (l); + if (res != 0) + { + if (program) + _dl_fatal_printf ("%s: fail to mark legacy code region\n", + l->l_name); + else + _dl_signal_error (-res, l->l_name, "dlopen", + N_("fail to mark legacy code region")); + } + } + + /* Change legacy bitmap to read-only. */ + if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0], + GL(dl_x86_legacy_bitmap)[1], PROT_READ) < 0) + goto mprotect_failure; + } + } + + bool cet_feature_changed = false; + + if (enable_ibt != ibt_enabled || enable_shstk != shstk_enabled) + { + if (!program + && enable_shstk_type != CET_PERMISSIVE) + { + /* When SHSTK is enabled, we can't dlopening a shared + object without SHSTK. */ + if (enable_shstk != shstk_enabled) + _dl_signal_error (EINVAL, l->l_name, "dlopen", + N_("shadow stack isn't enabled")); + return; + } + + /* Disable IBT and/or SHSTK if they are enabled by kernel, but + disabled in executable or shared objects. */ + unsigned int cet_feature = 0; + + /* Disable IBT only during program startup. */ + if (program && !enable_ibt) + cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT; + if (!enable_shstk) + cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK; + + int res = dl_cet_disable_cet (cet_feature); + if (res != 0) + { + if (program) + _dl_fatal_printf ("%s: can't disable CET\n", program); + else + _dl_signal_error (-res, l->l_name, "dlopen", + N_("can't disable CET")); + } + + /* Clear the disabled bits in dl_x86_feature_1. */ + GL(dl_x86_feature_1)[0] &= ~cet_feature; + + cet_feature_changed = true; + } + +#ifdef SHARED + if (program + && (!shstk_enabled + || enable_shstk_type != CET_PERMISSIVE) + && (ibt_enabled || shstk_enabled)) + { + /* Lock CET if IBT or SHSTK is enabled in executable. Don't + lock CET if SHSTK is enabled permissively. */ + int res = dl_cet_lock_cet (); + if (res != 0) + _dl_fatal_printf ("%s: can't lock CET\n", program); + + cet_feature_changed = true; + } +#endif + + if (cet_feature_changed) + { + unsigned int feature_1 = 0; + if (enable_ibt) + feature_1 |= GNU_PROPERTY_X86_FEATURE_1_IBT; + if (enable_shstk) + feature_1 |= GNU_PROPERTY_X86_FEATURE_1_SHSTK; + struct pthread *self = THREAD_SELF; + THREAD_SETMEM (self, header.feature_1, feature_1); + } + } +} + +void +_dl_cet_open_check (struct link_map *l) +{ + dl_cet_check (l, NULL); +} + +#ifdef SHARED + +# ifndef LINKAGE +# define LINKAGE +# endif + +LINKAGE +void +_dl_cet_check (struct link_map *main_map, const char *program) +{ + dl_cet_check (main_map, program); +} +#endif /* SHARED */ diff --git a/sysdeps/x86/dl-procruntime.c b/sysdeps/x86/dl-procruntime.c new file mode 100644 index 0000000000..eddbde6a31 --- /dev/null +++ b/sysdeps/x86/dl-procruntime.c @@ -0,0 +1,68 @@ +/* Data for processor runtime information. x86 version. + Copyright (C) 2018 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +/* This information must be kept in sync with the _DL_HWCAP_COUNT, + HWCAP_PLATFORMS_START and HWCAP_PLATFORMS_COUNT definitions in + dl-hwcap.h. + + If anything should be added here check whether the size of each string + is still ok with the given array size. + + All the #ifdefs in the definitions are quite irritating but + necessary if we want to avoid duplicating the information. There + are three different modes: + + - PROCINFO_DECL is defined. This means we are only interested in + declarations. + + - PROCINFO_DECL is not defined: + + + if SHARED is defined the file is included in an array + initializer. The .element = { ... } syntax is needed. + + + if SHARED is not defined a normal array initialization is + needed. + */ + +#ifndef PROCINFO_CLASS +# define PROCINFO_CLASS +#endif + +#if !IS_IN (ldconfig) +# if !defined PROCINFO_DECL && defined SHARED + ._dl_x86_feature_1 +# else +PROCINFO_CLASS unsigned int _dl_x86_feature_1[2] +# endif +# if !defined SHARED || defined PROCINFO_DECL +; +# else +, +# endif + +# if !defined PROCINFO_DECL && defined SHARED + ._dl_x86_legacy_bitmap +# else +PROCINFO_CLASS unsigned long _dl_x86_legacy_bitmap[2] +# endif +# if !defined SHARED || defined PROCINFO_DECL +; +# else +, +# endif +#endif diff --git a/sysdeps/x86/dl-prop.h b/sysdeps/x86/dl-prop.h new file mode 100644 index 0000000000..2709fe852d --- /dev/null +++ b/sysdeps/x86/dl-prop.h @@ -0,0 +1,153 @@ +/* Support for GNU properties. x86 version. + Copyright (C) 2018 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#ifndef _DL_PROP_H +#define _DL_PROP_H + +#include + +extern void _dl_cet_check (struct link_map *, const char *) + attribute_hidden; +extern void _dl_cet_open_check (struct link_map *) + attribute_hidden; + +static inline void __attribute__ ((always_inline)) +_rtld_main_check (struct link_map *m, const char *program) +{ +#ifdef __CET__ + _dl_cet_check (m, program); +#endif +} + +static inline void __attribute__ ((always_inline)) +_dl_open_check (struct link_map *m) +{ +#ifdef __CET__ + _dl_cet_open_check (m); +#endif +} + +static inline void __attribute__ ((unused)) +_dl_process_cet_property_note (struct link_map *l, + const ElfW(Nhdr) *note, + const ElfW(Addr) size, + const ElfW(Addr) align) +{ +#ifdef __CET__ + /* The NT_GNU_PROPERTY_TYPE_0 note must be aliged to 4 bytes in + 32-bit objects and to 8 bytes in 64-bit objects. Skip notes + with incorrect alignment. */ + if (align != (__ELF_NATIVE_CLASS / 8)) + return; + + const ElfW(Addr) start = (ElfW(Addr)) note; + + while ((ElfW(Addr)) (note + 1) - start < size) + { + /* Find the NT_GNU_PROPERTY_TYPE_0 note. */ + if (note->n_namesz == 4 + && note->n_type == NT_GNU_PROPERTY_TYPE_0 + && memcmp (note + 1, "GNU", 4) == 0) + { + /* Check for invalid property. */ + if (note->n_descsz < 8 + || (note->n_descsz % sizeof (ElfW(Addr))) != 0) + break; + + /* Start and end of property array. */ + unsigned char *ptr = (unsigned char *) (note + 1) + 4; + unsigned char *ptr_end = ptr + note->n_descsz; + + while (1) + { + unsigned int type = *(unsigned int *) ptr; + unsigned int datasz = *(unsigned int *) (ptr + 4); + + ptr += 8; + if ((ptr + datasz) > ptr_end) + break; + + if (type == GNU_PROPERTY_X86_FEATURE_1_AND + && datasz == 4) + { + unsigned int feature_1 = *(unsigned int *) ptr; + if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_IBT)) + l->l_cet |= lc_ibt; + if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_SHSTK)) + l->l_cet |= lc_shstk; + break; + } + } + } + + /* NB: Note sections like .note.ABI-tag and .note.gnu.build-id are + aligned to 4 bytes in 64-bit ELF objects. */ + note = ((const void *) note + + ELF_NOTE_NEXT_OFFSET (note->n_namesz, note->n_descsz, + align)); + } +#endif +} + +#ifdef FILEBUF_SIZE +static inline int __attribute__ ((unused)) +_dl_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph, + int fd, struct filebuf *fbp) +{ +# ifdef __CET__ + const ElfW(Nhdr) *note; + ElfW(Nhdr) *note_malloced = NULL; + ElfW(Addr) size = ph->p_filesz; + + if (ph->p_offset + size <= (size_t) fbp->len) + note = (const void *) (fbp->buf + ph->p_offset); + else + { + if (size < __MAX_ALLOCA_CUTOFF) + note = alloca (size); + else + { + note_malloced = malloc (size); + note = note_malloced; + } + __lseek (fd, ph->p_offset, SEEK_SET); + if (__read_nocancel (fd, (void *) note, size) != size) + { + if (note_malloced) + free (note_malloced); + return -1; + } + } + + _dl_process_cet_property_note (l, note, size, ph->p_align); + if (note_malloced) + free (note_malloced); +# endif + return 0; +} +#endif + +static inline int __attribute__ ((unused)) +_rtld_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph) +{ + const ElfW(Nhdr) *note = (const void *) (ph->p_vaddr + l->l_addr); + _dl_process_cet_property_note (l, note, ph->p_memsz, ph->p_align); + return 0; +} + +#endif /* _DL_PROP_H */ diff --git a/sysdeps/x86/dl-tunables.list b/sysdeps/x86/dl-tunables.list index 7c3236a68f..73886b1352 100644 --- a/sysdeps/x86/dl-tunables.list +++ b/sysdeps/x86/dl-tunables.list @@ -21,6 +21,12 @@ glibc { hwcaps { type: STRING } + x86_ibt { + type: STRING + } + x86_shstk { + type: STRING + } x86_non_temporal_threshold { type: SIZE_T } diff --git a/sysdeps/x86/libc-start.h b/sysdeps/x86/libc-start.h new file mode 100644 index 0000000000..6f44262bf4 --- /dev/null +++ b/sysdeps/x86/libc-start.h @@ -0,0 +1,25 @@ +/* X86 definitions for libc main startup. + Copyright (C) 2018 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#ifndef SHARED +# define ARCH_SETUP_IREL() apply_irel () +# define ARCH_APPLY_IREL() +# ifndef ARCH_SETUP_TLS +# define ARCH_SETUP_TLS() __libc_setup_tls () +# endif +#endif /* !SHARED */ diff --git a/sysdeps/x86/link_map.h b/sysdeps/x86/link_map.h new file mode 100644 index 0000000000..ef1206a9d2 --- /dev/null +++ b/sysdeps/x86/link_map.h @@ -0,0 +1,26 @@ +/* Additional fields in struct link_map. Linux/x86 version. + Copyright (C) 2018 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +/* If this object is enabled with CET. */ +enum + { + lc_none = 0, /* Not enabled with CET. */ + lc_ibt = 1 << 0, /* Enabled with IBT. */ + lc_shstk = 1 << 1, /* Enabled with STSHK. */ + lc_ibt_and_shstk = lc_ibt | lc_shstk /* Enabled with both. */ + } l_cet:2; diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h index afcb7cfd76..9843d9dff7 100644 --- a/sysdeps/x86/sysdep.h +++ b/sysdeps/x86/sysdep.h @@ -25,6 +25,13 @@ /* Syntactic details of assembler. */ +#ifdef _CET_ENDBR +# define _CET_NOTRACK notrack +#else +# define _CET_ENDBR +# define _CET_NOTRACK +#endif + /* ELF uses byte-counts for .align, most others use log2 of count of bytes. */ #define ALIGNARG(log2) 1<