From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Martin Subject: [PATCH 6/8] elf: Allow arch to tweak initial mmap prot flags Date: Fri, 24 May 2019 11:25:31 +0100 Message-ID: <1558693533-13465-7-git-send-email-Dave.Martin@arm.com> References: <1558693533-13465-1-git-send-email-Dave.Martin@arm.com> Return-path: In-Reply-To: <1558693533-13465-1-git-send-email-Dave.Martin@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Yu-cheng Yu , "H.J. Lu" , Arnd Bergmann , Richard Henderson , Andrew Jones , Will Deacon , Catalin Marinas , =?UTF-8?q?Kristina=20Mart=C5=A1enko?= , Szabolcs Nagy , Sudakshina Das , Paul Elliott List-Id: linux-arch.vger.kernel.org An arch may want to tweak the mmap prot flags for an ELF executable's initial mappings. For example, arm64 is going to need to add PROT_BTI_GUARDED for executable pages in an ELF process whose executable is marked as using Branch Target Identification (an ARMv8.5-A control flow integrity feature). So that this can be done in a generic way, add a hook arch_elf_adjust_prot() to modify the prot flags as desired: arches can select CONFIG_HAVE_ELF_PROT and implement their own backend where necessary. By default, leave the prot flags unchanged. Signed-off-by: Dave Martin --- fs/Kconfig.binfmt | 3 +++ fs/binfmt_elf.c | 18 ++++++++++++------ include/linux/elf.h | 13 +++++++++++++ 3 files changed, 28 insertions(+), 6 deletions(-) diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt index 175a1f5..cd3d315 100644 --- a/fs/Kconfig.binfmt +++ b/fs/Kconfig.binfmt @@ -35,6 +35,9 @@ config COMPAT_BINFMT_ELF config ARCH_BINFMT_ELF_STATE bool +config ARCH_HAVE_ELF_PROT + bool + config ARCH_USE_GNU_PROPERTY bool depends on 64BIT diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 32c9c13..3d88dcc 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -524,7 +524,8 @@ static inline int arch_check_elf(struct elfhdr *ehdr, bool has_interp, #endif /* !CONFIG_ARCH_BINFMT_ELF_STATE */ -static inline int make_prot(u32 p_flags) +static inline int make_prot(u32 p_flags, struct arch_elf_state *arch_state, + bool has_interp, bool is_interp) { int prot = 0; @@ -534,7 +535,8 @@ static inline int make_prot(u32 p_flags) prot |= PROT_WRITE; if (p_flags & PF_X) prot |= PROT_EXEC; - return prot; + + return arch_elf_adjust_prot(prot, arch_state, has_interp, is_interp); } /* This is much more generalized than the library routine read function, @@ -544,7 +546,8 @@ static inline int make_prot(u32 p_flags) static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, struct file *interpreter, unsigned long *interp_map_addr, - unsigned long no_base, struct elf_phdr *interp_elf_phdata) + unsigned long no_base, struct elf_phdr *interp_elf_phdata, + struct arch_elf_state *arch_state) { struct elf_phdr *eppnt; unsigned long load_addr = 0; @@ -576,7 +579,8 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, for (i = 0; i < interp_elf_ex->e_phnum; i++, eppnt++) { if (eppnt->p_type == PT_LOAD) { int elf_type = MAP_PRIVATE | MAP_DENYWRITE; - int elf_prot = make_prot(eppnt->p_flags); + int elf_prot = make_prot(eppnt->p_flags, arch_state, + true, true); unsigned long vaddr = 0; unsigned long k, map_addr; @@ -952,7 +956,8 @@ static int load_elf_binary(struct linux_binprm *bprm) elf_fixed = MAP_FIXED; } - elf_prot = make_prot(elf_ppnt->p_flags); + elf_prot = make_prot(elf_ppnt->p_flags, &arch_state, + !!interpreter, false); elf_flags = MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE; @@ -1098,7 +1103,8 @@ static int load_elf_binary(struct linux_binprm *bprm) elf_entry = load_elf_interp(&loc->interp_elf_ex, interpreter, &interp_map_addr, - load_bias, interp_elf_phdata); + load_bias, interp_elf_phdata, + &arch_state); if (!IS_ERR((void *)elf_entry)) { /* * load_elf_interp() returns relocation diff --git a/include/linux/elf.h b/include/linux/elf.h index cfcf154..2057187 100644 --- a/include/linux/elf.h +++ b/include/linux/elf.h @@ -75,4 +75,17 @@ static inline int arch_parse_property(void *ehdr, void *phdr, struct file *f, static inline int get_gnu_property(void *ehdr_p, void *phdr_p, struct file *f, u32 pr_type, u32 *feature) { return 0; } #endif + +#ifdef CONFIG_ARCH_HAVE_ELF_PROT +int arch_elf_adjust_prot(int prot, const struct arch_elf_state *state, + bool has_interp, bool is_interp); +#else +static inline int arch_elf_adjust_prot(int prot, + const struct arch_elf_state *state, + bool has_interp, bool is_interp) +{ + return prot; +} +#endif + #endif /* _LINUX_ELF_H */ -- 2.1.4 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:39272 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390649AbfEXK0h (ORCPT ); Fri, 24 May 2019 06:26:37 -0400 From: Dave Martin Subject: [PATCH 6/8] elf: Allow arch to tweak initial mmap prot flags Date: Fri, 24 May 2019 11:25:31 +0100 Message-ID: <1558693533-13465-7-git-send-email-Dave.Martin@arm.com> In-Reply-To: <1558693533-13465-1-git-send-email-Dave.Martin@arm.com> References: <1558693533-13465-1-git-send-email-Dave.Martin@arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Yu-cheng Yu , "H.J. Lu" , Arnd Bergmann , Richard Henderson , Andrew Jones , Will Deacon , Catalin Marinas , =?UTF-8?q?Kristina=20Mart=C5=A1enko?= , Szabolcs Nagy , Sudakshina Das , Paul Elliott Message-ID: <20190524102531.IcZNc5Z4D78RO0gWQBur6f9pzryug7Um86dgdRAYuzs@z> An arch may want to tweak the mmap prot flags for an ELF executable's initial mappings. For example, arm64 is going to need to add PROT_BTI_GUARDED for executable pages in an ELF process whose executable is marked as using Branch Target Identification (an ARMv8.5-A control flow integrity feature). So that this can be done in a generic way, add a hook arch_elf_adjust_prot() to modify the prot flags as desired: arches can select CONFIG_HAVE_ELF_PROT and implement their own backend where necessary. By default, leave the prot flags unchanged. Signed-off-by: Dave Martin --- fs/Kconfig.binfmt | 3 +++ fs/binfmt_elf.c | 18 ++++++++++++------ include/linux/elf.h | 13 +++++++++++++ 3 files changed, 28 insertions(+), 6 deletions(-) diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt index 175a1f5..cd3d315 100644 --- a/fs/Kconfig.binfmt +++ b/fs/Kconfig.binfmt @@ -35,6 +35,9 @@ config COMPAT_BINFMT_ELF config ARCH_BINFMT_ELF_STATE bool +config ARCH_HAVE_ELF_PROT + bool + config ARCH_USE_GNU_PROPERTY bool depends on 64BIT diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 32c9c13..3d88dcc 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -524,7 +524,8 @@ static inline int arch_check_elf(struct elfhdr *ehdr, bool has_interp, #endif /* !CONFIG_ARCH_BINFMT_ELF_STATE */ -static inline int make_prot(u32 p_flags) +static inline int make_prot(u32 p_flags, struct arch_elf_state *arch_state, + bool has_interp, bool is_interp) { int prot = 0; @@ -534,7 +535,8 @@ static inline int make_prot(u32 p_flags) prot |= PROT_WRITE; if (p_flags & PF_X) prot |= PROT_EXEC; - return prot; + + return arch_elf_adjust_prot(prot, arch_state, has_interp, is_interp); } /* This is much more generalized than the library routine read function, @@ -544,7 +546,8 @@ static inline int make_prot(u32 p_flags) static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, struct file *interpreter, unsigned long *interp_map_addr, - unsigned long no_base, struct elf_phdr *interp_elf_phdata) + unsigned long no_base, struct elf_phdr *interp_elf_phdata, + struct arch_elf_state *arch_state) { struct elf_phdr *eppnt; unsigned long load_addr = 0; @@ -576,7 +579,8 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, for (i = 0; i < interp_elf_ex->e_phnum; i++, eppnt++) { if (eppnt->p_type == PT_LOAD) { int elf_type = MAP_PRIVATE | MAP_DENYWRITE; - int elf_prot = make_prot(eppnt->p_flags); + int elf_prot = make_prot(eppnt->p_flags, arch_state, + true, true); unsigned long vaddr = 0; unsigned long k, map_addr; @@ -952,7 +956,8 @@ static int load_elf_binary(struct linux_binprm *bprm) elf_fixed = MAP_FIXED; } - elf_prot = make_prot(elf_ppnt->p_flags); + elf_prot = make_prot(elf_ppnt->p_flags, &arch_state, + !!interpreter, false); elf_flags = MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE; @@ -1098,7 +1103,8 @@ static int load_elf_binary(struct linux_binprm *bprm) elf_entry = load_elf_interp(&loc->interp_elf_ex, interpreter, &interp_map_addr, - load_bias, interp_elf_phdata); + load_bias, interp_elf_phdata, + &arch_state); if (!IS_ERR((void *)elf_entry)) { /* * load_elf_interp() returns relocation diff --git a/include/linux/elf.h b/include/linux/elf.h index cfcf154..2057187 100644 --- a/include/linux/elf.h +++ b/include/linux/elf.h @@ -75,4 +75,17 @@ static inline int arch_parse_property(void *ehdr, void *phdr, struct file *f, static inline int get_gnu_property(void *ehdr_p, void *phdr_p, struct file *f, u32 pr_type, u32 *feature) { return 0; } #endif + +#ifdef CONFIG_ARCH_HAVE_ELF_PROT +int arch_elf_adjust_prot(int prot, const struct arch_elf_state *state, + bool has_interp, bool is_interp); +#else +static inline int arch_elf_adjust_prot(int prot, + const struct arch_elf_state *state, + bool has_interp, bool is_interp) +{ + return prot; +} +#endif + #endif /* _LINUX_ELF_H */ -- 2.1.4