diff options
Diffstat (limited to 'arch/arm/kernel/elf.c')
| -rw-r--r-- | arch/arm/kernel/elf.c | 52 |
1 files changed, 47 insertions, 5 deletions
diff --git a/arch/arm/kernel/elf.c b/arch/arm/kernel/elf.c index d0d1e83150c9..254ab7138c85 100644 --- a/arch/arm/kernel/elf.c +++ b/arch/arm/kernel/elf.c @@ -1,8 +1,10 @@ +// SPDX-License-Identifier: GPL-2.0 #include <linux/export.h> #include <linux/sched.h> #include <linux/personality.h> #include <linux/binfmts.h> #include <linux/elf.h> +#include <linux/elf-fdpic.h> #include <asm/system_info.h> int elf_check_arch(const struct elf32_hdr *x) @@ -76,16 +78,56 @@ void elf_set_personality(const struct elf32_hdr *x) EXPORT_SYMBOL(elf_set_personality); /* - * Set READ_IMPLIES_EXEC if: - * - the binary requires an executable stack - * - we're running on a CPU which doesn't support NX. + * An executable for which elf_read_implies_exec() returns TRUE will + * have the READ_IMPLIES_EXEC personality flag set automatically. + * + * The decision process for determining the results are: + * + * CPU: | lacks NX* | has NX | + * ELF: | | | + * ---------------------|------------|------------| + * missing PT_GNU_STACK | exec-all | exec-all | + * PT_GNU_STACK == RWX | exec-all | exec-stack | + * PT_GNU_STACK == RW | exec-all | exec-none | + * + * exec-all : all PROT_READ user mappings are executable, except when + * backed by files on a noexec-filesystem. + * exec-none : only PROT_EXEC user mappings are executable. + * exec-stack: only the stack and PROT_EXEC user mappings are executable. + * + * *this column has no architectural effect: NX markings are ignored by + * hardware, but may have behavioral effects when "wants X" collides with + * "cannot be X" constraints in memory permission flags, as in + * https://lkml.kernel.org/r/20190418055759.GA3155@mellanox.com + * */ -int arm_elf_read_implies_exec(const struct elf32_hdr *x, int executable_stack) +int arm_elf_read_implies_exec(int executable_stack) { - if (executable_stack != EXSTACK_DISABLE_X) + if (executable_stack == EXSTACK_DEFAULT) return 1; if (cpu_architecture() < CPU_ARCH_ARMv6) return 1; return 0; } EXPORT_SYMBOL(arm_elf_read_implies_exec); + +#if defined(CONFIG_MMU) && defined(CONFIG_BINFMT_ELF_FDPIC) + +void elf_fdpic_arch_lay_out_mm(struct elf_fdpic_params *exec_params, + struct elf_fdpic_params *interp_params, + unsigned long *start_stack, + unsigned long *start_brk) +{ + elf_set_personality(&exec_params->hdr); + + exec_params->load_addr = 0x8000; + interp_params->load_addr = ELF_ET_DYN_BASE; + *start_stack = TASK_SIZE - SZ_16M; + + if ((exec_params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) == ELF_FDPIC_FLAG_INDEPENDENT) { + exec_params->flags &= ~ELF_FDPIC_FLAG_ARRANGEMENT; + exec_params->flags |= ELF_FDPIC_FLAG_CONSTDISP; + } +} + +#endif |