From patchwork Mon Apr 4 09:44:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 52613 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 62ED23858D1E for ; Mon, 4 Apr 2022 09:45:38 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 62ED23858D1E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1649065538; bh=kbmkDL319991kPUPrECLVrx36KCgN3jGpE0qz3e9tfo=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=PwoxlxPq5IITgyAS/x+HaUFqNKhEHRRyGgwGhpkxpxgS7QXT9VDcHz7Lrth3nG9AD eUQPi1afwHefT9+vnWTcV4VUeSpfi1lw4nm2kKveaQbcac1XGgax8/chm0CSeEdh2I LqdIRRzqtJfwExt7qURm3CKaqX20V0BZ9s5xKc8A= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by sourceware.org (Postfix) with ESMTPS id A30BB3858405 for ; Mon, 4 Apr 2022 09:44:36 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org A30BB3858405 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9C6C3B8087F; Mon, 4 Apr 2022 09:44:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA063C34112; Mon, 4 Apr 2022 09:44:31 +0000 (UTC) To: Catalin Marinas , Will Deacon Subject: [PATCH v12 1/2] elf: Allow architectures to parse properties on the main executable Date: Mon, 4 Apr 2022 10:44:24 +0100 Message-Id: <20220404094425.313821-2-broonie@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220404094425.313821-1-broonie@kernel.org> References: <20220404094425.313821-1-broonie@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6534; h=from:subject; bh=ZQzHyj8xOGFbywMAfv75IiikXgfACmOT2q6BmmO69vI=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBiSr33vU6ehNHbYsxlzSqHnySV8L0qzs2jtzBDlhw6 mNhP5UeJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCYkq99wAKCRAk1otyXVSH0GU3B/ oDRBhOFi/tq3K4AGAkNKbi5rvdCy7kBNA0BWq+/6qRFwGWt7r1n0VI7Pfb39DznX/ojX1tJ9kO1+EW FUyqqI+WAHR8lkFZV5VTWcFYEcjsTIYw4wxSYwU6yu5w8dBoOQy7rheDGV/gv7YfuGLzRzlCLabFav IIUPKSRU6bWd6Tvq4V6cNY/99IJ35pu8wMpvGJY4ANPJew82Zj2aIZAsukxA/xHU7Hxf/Gj48cneFT yPIf3yvx8+bhLmLzkugxyeCfddYHXoTBiPyh16vREzurRd+V2fbsMdRJ6uNc/UtbaBQqMR9Ozq9SJi e2DffL9RaBi9/jNbdTqWhTHb4PnLrt X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB X-Spam-Status: No, score=-11.0 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Mark Brown via Libc-alpha From: Mark Brown Reply-To: Mark Brown Cc: linux-arch@vger.kernel.org, Yu-cheng Yu , libc-alpha@sourceware.org, Kees Cook , Szabolcs Nagy , Jeremy Linton , Mark Brown , Dave Martin , linux-arm-kernel@lists.infradead.org Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Currently the ELF code only attempts to parse properties on the image that will start execution, either the interpreter or for statically linked executables the main executable. The expectation is that any property handling for the main executable will be done by the interpreter. This is a bit inconsistent since we do map the executable and is causing problems for the arm64 BTI support when used in conjunction with systemd's use of seccomp to implement MemoryDenyWriteExecute which stops the dynamic linker adjusting the permissions of executable segments. Allow architectures to handle properties for both the dynamic linker and main executable, adjusting arch_parse_elf_properties() to have a new flag is_interp flag as with arch_elf_adjust_prot() and calling it for both the main executable and any intepreter. The user of this code, arm64, is adapted to ensure that there is no functional change. Signed-off-by: Mark Brown Tested-by: Jeremy Linton Reviewed-by: Dave Martin Reviewed-by: Catalin Marinas --- arch/arm64/include/asm/elf.h | 3 ++- fs/binfmt_elf.c | 34 ++++++++++++++++++++++++---------- include/linux/elf.h | 4 +++- 3 files changed, 29 insertions(+), 12 deletions(-) diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index 97932fbf973d..5cc002376abe 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -259,6 +259,7 @@ struct arch_elf_state { static inline int arch_parse_elf_property(u32 type, const void *data, size_t datasz, bool compat, + bool has_interp, bool is_interp, struct arch_elf_state *arch) { /* No known properties for AArch32 yet */ @@ -271,7 +272,7 @@ static inline int arch_parse_elf_property(u32 type, const void *data, if (datasz != sizeof(*p)) return -ENOEXEC; - if (system_supports_bti() && + if (system_supports_bti() && has_interp == is_interp && (*p & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)) arch->flags |= ARM64_ELF_BTI; } diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 6556e13ed95f..ecd462bddb7e 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -717,8 +717,9 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, */ static int parse_elf_property(const char *data, size_t *off, size_t datasz, - struct arch_elf_state *arch, - bool have_prev_type, u32 *prev_type) + struct arch_elf_state *arch, bool has_interp, + bool is_interp, bool have_prev_type, + u32 *prev_type) { size_t o, step; const struct gnu_property *pr; @@ -752,7 +753,8 @@ static int parse_elf_property(const char *data, size_t *off, size_t datasz, *prev_type = pr->pr_type; ret = arch_parse_elf_property(pr->pr_type, data + o, - pr->pr_datasz, ELF_COMPAT, arch); + pr->pr_datasz, ELF_COMPAT, + has_interp, is_interp, arch); if (ret) return ret; @@ -765,6 +767,7 @@ static int parse_elf_property(const char *data, size_t *off, size_t datasz, #define NOTE_NAME_SZ (sizeof(GNU_PROPERTY_TYPE_0_NAME)) static int parse_elf_properties(struct file *f, const struct elf_phdr *phdr, + bool has_interp, bool is_interp, struct arch_elf_state *arch) { union { @@ -814,7 +817,8 @@ static int parse_elf_properties(struct file *f, const struct elf_phdr *phdr, have_prev_type = false; do { ret = parse_elf_property(note.data, &off, datasz, arch, - have_prev_type, &prev_type); + has_interp, is_interp, have_prev_type, + &prev_type); have_prev_type = true; } while (!ret); @@ -829,6 +833,7 @@ static int load_elf_binary(struct linux_binprm *bprm) unsigned long error; struct elf_phdr *elf_ppnt, *elf_phdata, *interp_elf_phdata = NULL; struct elf_phdr *elf_property_phdata = NULL; + struct elf_phdr *interp_elf_property_phdata = NULL; unsigned long elf_bss, elf_brk; int bss_prot = 0; int retval, i; @@ -866,12 +871,15 @@ static int load_elf_binary(struct linux_binprm *bprm) for (i = 0; i < elf_ex->e_phnum; i++, elf_ppnt++) { char *elf_interpreter; + if (interpreter && elf_property_phdata) + break; + if (elf_ppnt->p_type == PT_GNU_PROPERTY) { elf_property_phdata = elf_ppnt; continue; } - if (elf_ppnt->p_type != PT_INTERP) + if (interpreter || elf_ppnt->p_type != PT_INTERP) continue; /* @@ -920,7 +928,7 @@ static int load_elf_binary(struct linux_binprm *bprm) if (retval < 0) goto out_free_dentry; - break; + continue; out_free_interp: kfree(elf_interpreter); @@ -964,12 +972,11 @@ static int load_elf_binary(struct linux_binprm *bprm) goto out_free_dentry; /* Pass PT_LOPROC..PT_HIPROC headers to arch code */ - elf_property_phdata = NULL; elf_ppnt = interp_elf_phdata; for (i = 0; i < interp_elf_ex->e_phnum; i++, elf_ppnt++) switch (elf_ppnt->p_type) { case PT_GNU_PROPERTY: - elf_property_phdata = elf_ppnt; + interp_elf_property_phdata = elf_ppnt; break; case PT_LOPROC ... PT_HIPROC: @@ -980,10 +987,17 @@ static int load_elf_binary(struct linux_binprm *bprm) goto out_free_dentry; break; } + + retval = parse_elf_properties(interpreter, + interp_elf_property_phdata, + true, true, &arch_state); + if (retval) + goto out_free_dentry; + } - retval = parse_elf_properties(interpreter ?: bprm->file, - elf_property_phdata, &arch_state); + retval = parse_elf_properties(bprm->file, elf_property_phdata, + interpreter, false, &arch_state); if (retval) goto out_free_dentry; diff --git a/include/linux/elf.h b/include/linux/elf.h index c9a46c4e183b..1c45ecf29147 100644 --- a/include/linux/elf.h +++ b/include/linux/elf.h @@ -88,13 +88,15 @@ struct arch_elf_state; #ifndef CONFIG_ARCH_USE_GNU_PROPERTY static inline int arch_parse_elf_property(u32 type, const void *data, size_t datasz, bool compat, + bool has_interp, bool is_interp, struct arch_elf_state *arch) { return 0; } #else extern int arch_parse_elf_property(u32 type, const void *data, size_t datasz, - bool compat, struct arch_elf_state *arch); + bool compat, bool has_interp, bool is_interp, + struct arch_elf_state *arch); #endif #ifdef CONFIG_ARCH_HAVE_ELF_PROT From patchwork Mon Apr 4 09:44:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 52614 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 4C2063858C53 for ; Mon, 4 Apr 2022 09:46:20 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4C2063858C53 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1649065580; bh=53JAmCbbxwYYqlbiSRkvibAV4gBaVOyeZsHA1rz19Xg=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=tHDG2wmUPvitFG1WVq4AsaT5zfa/4eAbkZfeBL9dmluu1O8+RDrA3B2X43Fk/hxWq jzoGbaMJYjfeWraPr5S7UJkl9Cf/+RtB2vY7fYHGEkEOulxOb24rvsdmJQlcstNViH jsM2Xv/qg+OLiRNyTc5Z0gIvH/i0LCAw38amO7GA= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by sourceware.org (Postfix) with ESMTPS id 6C99A385840C for ; Mon, 4 Apr 2022 09:44:38 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 6C99A385840C Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DFD2160FA1; Mon, 4 Apr 2022 09:44:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DBDD8C34111; Mon, 4 Apr 2022 09:44:34 +0000 (UTC) To: Catalin Marinas , Will Deacon Subject: [PATCH v12 2/2] arm64: Enable BTI for main executable as well as the interpreter Date: Mon, 4 Apr 2022 10:44:25 +0100 Message-Id: <20220404094425.313821-3-broonie@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220404094425.313821-1-broonie@kernel.org> References: <20220404094425.313821-1-broonie@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3954; h=from:subject; bh=nM87AwZCcIUCsNfFiO7pQEUlSzAKS0CjflMvMdi3+ho=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBiSr33GvNrKBRXCqc6UFafyHsWfsmmdTrCliDNXBSv UpscniiJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCYkq99wAKCRAk1otyXVSH0NKgB/ 0XCk3kRSvXHsxbSHe+clYSh1G0y5XDTqaEeyLTsjhpySX7Qz1om6P1HHhuH8wONvbP7/Tel/IMKpwF WAEwAxtqbpKCh6SciYdcs792OuUlbgPXzqQebPtedBBgZkmcsffJGzjhAz5lCxs4Bal4h2cPmMrLWa P4N/nq4XMrstK6Ay+00oBvgabv2oru4bkw4XL/Th54kxjacuGQ7jku3cM9XUb0ryOtXT7Yh/tnLjLH B1+5vEU+vsImgXsFPejpb1hV8L/8QKuSd5m5PiNznHCTkIQmGAQqWowVoTD7V92Jh2CARGFwH46jzz hRCw09QmqNYEd4HxIU2d1TV3FXWxZa X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB X-Spam-Status: No, score=-11.1 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Mark Brown via Libc-alpha From: Mark Brown Reply-To: Mark Brown Cc: linux-arch@vger.kernel.org, Yu-cheng Yu , libc-alpha@sourceware.org, Kees Cook , Szabolcs Nagy , Jeremy Linton , Mark Brown , linux-arm-kernel@lists.infradead.org Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Currently for dynamically linked ELF executables we only enable BTI for the interpreter, expecting the interpreter to do this for the main executable. This is a bit inconsistent since we do map main executable and is causing issues with systemd's MemoryDenyWriteExecute feature which is implemented using a seccomp filter which prevents setting PROT_EXEC on already mapped memory and lacks the context to be able to detect that memory is already mapped with PROT_EXEC. Resolve this by adding a sysctl abi.bti_main which causes the kernel to checking the BTI property for the main executable and enable BTI if it is present when doing the initial mapping. This sysctl is disabled by default. Signed-off-by: Mark Brown Reviewed-by: Catalin Marinas --- arch/arm64/include/asm/elf.h | 15 ++++++++--- arch/arm64/kernel/process.c | 52 +++++++++++++++++++++++++++--------- 2 files changed, 51 insertions(+), 16 deletions(-) diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index 5cc002376abe..c4aa60db76a4 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -251,12 +251,21 @@ struct arch_elf_state { int flags; }; -#define ARM64_ELF_BTI (1 << 0) +#define ARM64_ELF_INTERP_BTI (1 << 0) +#define ARM64_ELF_EXEC_BTI (1 << 1) #define INIT_ARCH_ELF_STATE { \ .flags = 0, \ } +static inline int arm64_elf_bti_flag(bool is_interp) +{ + if (is_interp) + return ARM64_ELF_INTERP_BTI; + else + return ARM64_ELF_EXEC_BTI; +} + static inline int arch_parse_elf_property(u32 type, const void *data, size_t datasz, bool compat, bool has_interp, bool is_interp, @@ -272,9 +281,9 @@ static inline int arch_parse_elf_property(u32 type, const void *data, if (datasz != sizeof(*p)) return -ENOEXEC; - if (system_supports_bti() && has_interp == is_interp && + if (system_supports_bti() && (*p & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)) - arch->flags |= ARM64_ELF_BTI; + arch->flags |= arm64_elf_bti_flag(is_interp); } return 0; diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 7fa97df55e3a..665d375cc3f1 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -702,23 +702,49 @@ core_initcall(tagged_addr_init); #endif /* CONFIG_ARM64_TAGGED_ADDR_ABI */ #ifdef CONFIG_BINFMT_ELF +static unsigned int bti_main; + int arch_elf_adjust_prot(int prot, const struct arch_elf_state *state, bool has_interp, bool is_interp) { - /* - * For dynamically linked executables the interpreter is - * responsible for setting PROT_BTI on everything except - * itself. - */ - if (is_interp != has_interp) - return prot; - - if (!(state->flags & ARM64_ELF_BTI)) - return prot; - - if (prot & PROT_EXEC) + if ((prot & PROT_EXEC) && + (is_interp || !has_interp || bti_main) && + (state->flags & arm64_elf_bti_flag(is_interp))) prot |= PROT_BTI; return prot; } -#endif + +#ifdef CONFIG_ARM64_BTI +/* + * If this sysctl is enabled then we will apply PROT_BTI to the main + * executable as well as the dynamic linker if it has the appropriate + * ELF note. It is disabled by default, in which case we will only + * apply PROT_BTI to the dynamic linker or static binaries. + */ +static struct ctl_table bti_main_sysctl_table[] = { + { + .procname = "bti_main", + .mode = 0644, + .data = &bti_main, + .maxlen = sizeof(int), + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, + { } +}; + +static int __init bti_main_init(void) +{ + if (!system_supports_bti()) + return 0; + + if (!register_sysctl("abi", bti_main_sysctl_table)) + return -EINVAL; + return 0; +} +core_initcall(bti_main_init); +#endif /* CONFIG_ARM64_BTI */ + +#endif /* CONFIG_BINFMT_ELF */