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https://github.com/edk2-porting/linux-next.git
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8ec53663d2
Add support for detecting non-executable stack binaries, and adjust permissions to prevent execution from data and stack areas. Also, ensure that READ_IMPLIES_EXEC is enabled for older CPUs where that is true, and for any executable-stack binary. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
80 lines
2.0 KiB
C
80 lines
2.0 KiB
C
#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/personality.h>
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#include <linux/binfmts.h>
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#include <linux/elf.h>
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int elf_check_arch(const struct elf32_hdr *x)
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{
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unsigned int eflags;
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/* Make sure it's an ARM executable */
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if (x->e_machine != EM_ARM)
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return 0;
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/* Make sure the entry address is reasonable */
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if (x->e_entry & 1) {
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if (!(elf_hwcap & HWCAP_THUMB))
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return 0;
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} else if (x->e_entry & 3)
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return 0;
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eflags = x->e_flags;
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if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN) {
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/* APCS26 is only allowed if the CPU supports it */
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if ((eflags & EF_ARM_APCS_26) && !(elf_hwcap & HWCAP_26BIT))
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return 0;
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/* VFP requires the supporting code */
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if ((eflags & EF_ARM_VFP_FLOAT) && !(elf_hwcap & HWCAP_VFP))
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return 0;
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}
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return 1;
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}
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EXPORT_SYMBOL(elf_check_arch);
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void elf_set_personality(const struct elf32_hdr *x)
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{
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unsigned int eflags = x->e_flags;
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unsigned int personality = PER_LINUX_32BIT;
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/*
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* APCS-26 is only valid for OABI executables
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*/
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if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN) {
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if (eflags & EF_ARM_APCS_26)
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personality = PER_LINUX;
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}
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set_personality(personality);
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/*
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* Since the FPA coprocessor uses CP1 and CP2, and iWMMXt uses CP0
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* and CP1, we only enable access to the iWMMXt coprocessor if the
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* binary is EABI or softfloat (and thus, guaranteed not to use
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* FPA instructions.)
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*/
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if (elf_hwcap & HWCAP_IWMMXT &&
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eflags & (EF_ARM_EABI_MASK | EF_ARM_SOFT_FLOAT)) {
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set_thread_flag(TIF_USING_IWMMXT);
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} else {
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clear_thread_flag(TIF_USING_IWMMXT);
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}
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}
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EXPORT_SYMBOL(elf_set_personality);
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/*
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* Set READ_IMPLIES_EXEC if:
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* - the binary requires an executable stack
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* - we're running on a CPU which doesn't support NX.
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*/
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int arm_elf_read_implies_exec(const struct elf32_hdr *x, int executable_stack)
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{
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if (executable_stack != EXSTACK_ENABLE_X)
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return 1;
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if (cpu_architecture() <= CPU_ARCH_ARMv6)
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return 1;
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return 0;
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}
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EXPORT_SYMBOL(arm_elf_read_implies_exec);
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