From patchwork Mon Feb 28 13:06:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 51445 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 1F20B3858424 for ; Mon, 28 Feb 2022 13:09:10 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1F20B3858424 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1646053750; bh=bzI/9f7gpFFFDbhcoA/dAcb5FgCxBCDD+eCj9y8Wv+U=; 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=oIZfjCXI3D+LeDuFAlagvGGbTvnw3nwXmyA93MQgA71yxsUZ4JPBeME3Ie6Y00we4 4t3gXGB/movN2x3rQcIVSWgJ9jWuVXjFPPLTm13DoAa/q9DZWq7e7Ui8Eh3HXPex8w npuaPuAcZBltQb8tQx6fiCHAJzO+Q7oyyl4PZI/E= 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 B43E03858435 for ; Mon, 28 Feb 2022 13:07:31 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B43E03858435 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 48494B81134; Mon, 28 Feb 2022 13:07:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E9ABC340F4; Mon, 28 Feb 2022 13:07:25 +0000 (UTC) To: Catalin Marinas , Will Deacon Subject: [PATCH v10 1/2] elf: Allow architectures to parse properties on the main executable Date: Mon, 28 Feb 2022 13:06:05 +0000 Message-Id: <20220228130606.1070960-2-broonie@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220228130606.1070960-1-broonie@kernel.org> References: <20220228130606.1070960-1-broonie@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6403; h=from:subject; bh=/U1z01SKSPhzU0z+TYcwWxB8xXNSRekAHfeqCGbIUCA=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBiHMi8Y7oKxIEg3iKPxhmpEwPWODH2GPNcG3jv7hP/ qP2SOI+JATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCYhzIvAAKCRAk1otyXVSH0F+LB/ 9A3C1fDOIDY8sW9GMiQ1szlqYu7AVrFsCFhIoI1MaM0WhZbRIZ8lFkblApTbehr/SvrGUppNfKwf6R AxlUPRMUzdFikAnZlyxuZiTqOtVNaHdjsc9bhqZLgfHS9UGQRqObLhPQDhx7dcxqjvZj1QmeoHbNxu mviFvrxZ0t51gWrjM40//DhxqEzQzL8xvnULIA5+fk6wx2N6nbOp0eiCwyS845HsH4nxM7KduFBVlO ygcmOcEc7LGHQ8ayQ9ojvrJ0DSht3IPRzODAZN1ED8mz3dgJGlPAx/w5PjSaG/4+J+/szJYhitxG6c 3/Q8ciEiSkJwrmvBLFAFqWJX7Petg0 X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB X-Spam-Status: No, score=-11.4 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 | 32 +++++++++++++++++++++++--------- include/linux/elf.h | 4 +++- 3 files changed, 28 insertions(+), 11 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 605017eb9349..08b6d992e298 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -716,8 +716,9 @@ 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; @@ -751,7 +752,8 @@ 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; @@ -764,6 +766,7 @@ 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 { @@ -813,7 +816,8 @@ 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); @@ -828,6 +832,7 @@ 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; @@ -865,6 +870,9 @@ 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; @@ -919,7 +927,7 @@ static int load_elf_binary(struct linux_binprm *bprm) if (retval < 0) goto out_free_dentry; - break; + continue; out_free_interp: kfree(elf_interpreter); @@ -963,12 +971,11 @@ 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: @@ -979,10 +986,17 @@ 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 Feb 28 13:06:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 51444 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 5A9363858424 for ; Mon, 28 Feb 2022 13:08:28 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5A9363858424 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1646053708; bh=0kgc2xbwwGsJcvToSkOAbBq5sH3GWA77PqwA5N0p1r0=; 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=dBEVUvz6v0E/+ruM7Ok4/MOZC+oSzXoiwOkUdFfjI8bZhD2Iby9gws+U7/z22vSA/ r8D+QRfGV2/MimVghv4rMUavFet0RzYp6W3yQmcTMTI056hJEC396X9UKaJJL7y9v8 W0rHbFY7c6rwkB9YMw8zStopCmru4Bhg7s+JCZLM= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by sourceware.org (Postfix) with ESMTPS id B19273858401 for ; Mon, 28 Feb 2022 13:07:31 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B19273858401 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 0F835612EC; Mon, 28 Feb 2022 13:07:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61320C340F3; Mon, 28 Feb 2022 13:07:28 +0000 (UTC) To: Catalin Marinas , Will Deacon Subject: [PATCH v10 2/2] arm64: Enable BTI for main executable as well as the interpreter Date: Mon, 28 Feb 2022 13:06:06 +0000 Message-Id: <20220228130606.1070960-3-broonie@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220228130606.1070960-1-broonie@kernel.org> References: <20220228130606.1070960-1-broonie@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3898; h=from:subject; bh=eR6+Nci0LoL7aKQRViLwzPw/KMTNexP4A1Vwsad7KCQ=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBiHMi9he8bGD/YxH1JoS8wLCTPp8TgwGqceU/x4SyL 9qOjL+aJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCYhzIvQAKCRAk1otyXVSH0O4SB/ 0b8J2hJzjFNvSHoSwCUFCMqb0Sr2QwZtyMY+w1yn9YSXOZsJ7M34Zbf/kK617tos9GKoaO8aVjMum3 NN/WBJBL5u5gIn1/NbFalycV5KdX3l7iIGeZ6PU6rWZ6whzTplc0vAaFQawlI+sX4ZoYFUlJZd3qvQ nPrFRErSQrNKoOfiAjE++bd9XJSDc64pNMdAoQmztT6SFPBymJtzFQt1/v7uO8/mGk8Ys8vbcJr/bV Qpye5QfD3U4pV9h33dcTzXdignXrqrwlIFzof1ck/bGe8Tp0DxA8iYkvo/BPuZ1JSuXiWotyJO0KjS bdf7r1XrOl6E9Yfnnijc3SvAunVFpA X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB X-Spam-Status: No, score=-11.3 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 --- 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 5369e649fa79..82aaf361fa17 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -701,23 +701,49 @@ 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 */