| 1 | |
| 2 | #include <linux/export.h>
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| 3 | #include <linux/sched.h>
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| 4 | #include <linux/personality.h>
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| 5 | #include <linux/binfmts.h>
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| 6 | #include <linux/elf.h>
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| 7 | #include <linux/elf-fdpic.h>
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| 8 | #include <asm/system_info.h>
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| 9 |
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| 10 | int elf_check_arch(const struct elf32_hdr *x)
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| 11 | {
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| 12 | unsigned int eflags;
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| 13 |
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| 14 |
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| 15 | if (x->e_machine != EM_ARM)
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| 16 | return 0;
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| 17 |
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| 18 |
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| 19 | if (x->e_entry & 1) {
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| 20 | if (!(elf_hwcap & HWCAP_THUMB))
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| 21 | return 0;
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| 22 | } else if (x->e_entry & 3)
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| 23 | return 0;
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| 24 |
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| 25 | eflags = x->e_flags;
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| 26 | if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN) {
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| 27 | unsigned int flt_fmt;
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| 28 |
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| 29 |
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| 30 | if ((eflags & EF_ARM_APCS_26) && !(elf_hwcap & HWCAP_26BIT))
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| 31 | return 0;
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| 32 |
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| 33 | flt_fmt = eflags & (EF_ARM_VFP_FLOAT | EF_ARM_SOFT_FLOAT);
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| 34 |
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| 35 |
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| 36 | if (flt_fmt == EF_ARM_VFP_FLOAT && !(elf_hwcap & HWCAP_VFP))
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| 37 | return 0;
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| 38 | }
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| 39 | return 1;
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| 40 | }
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| 41 | EXPORT_SYMBOL(elf_check_arch);
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| 42 |
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| 43 | void elf_set_personality(const struct elf32_hdr *x)
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| 44 | {
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| 45 | unsigned int eflags = x->e_flags;
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| 46 | unsigned int personality = current->personality & ~PER_MASK;
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| 47 |
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| 48 | |
| 49 | * We only support Linux ELF executables, so always set the
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| 50 | * personality to LINUX.
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| 51 |
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| 52 | personality |= PER_LINUX;
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| 53 |
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| 54 | |
| 55 | * APCS-26 is only valid for OABI executables
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| 56 |
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| 57 | if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN &&
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| 58 | (eflags & EF_ARM_APCS_26))
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| 59 | personality &= ~ADDR_LIMIT_32BIT;
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| 60 | else
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| 61 | personality |= ADDR_LIMIT_32BIT;
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| 62 |
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| 63 | set_personality(personality);
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| 64 |
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| 65 | |
| 66 | * Since the FPA coprocessor uses CP1 and CP2, and iWMMXt uses CP0
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| 67 | * and CP1, we only enable access to the iWMMXt coprocessor if the
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| 68 | * binary is EABI or softfloat (and thus, guaranteed not to use
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| 69 | * FPA instructions.)
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| 70 |
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| 71 | if (elf_hwcap & HWCAP_IWMMXT &&
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| 72 | eflags & (EF_ARM_EABI_MASK | EF_ARM_SOFT_FLOAT)) {
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| 73 | set_thread_flag(TIF_USING_IWMMXT);
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| 74 | } else {
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| 75 | clear_thread_flag(TIF_USING_IWMMXT);
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| 76 | }
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| 77 | }
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| 78 | EXPORT_SYMBOL(elf_set_personality);
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| 79 |
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| 80 | |
| 81 | * An executable for which elf_read_implies_exec() returns TRUE will
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| 82 | * have the READ_IMPLIES_EXEC personality flag set automatically.
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| 83 | *
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| 84 | * The decision process for determining the results are:
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| 85 | *
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| 86 | * CPU: | lacks NX* | has NX |
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| 87 | * ELF: | | |
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| 88 | * ---------------------|------------|------------|
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| 89 | * missing PT_GNU_STACK | exec-all | exec-all |
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| 90 | * PT_GNU_STACK == RWX | exec-all | exec-stack |
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| 91 | * PT_GNU_STACK == RW | exec-all | exec-none |
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| 92 | *
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| 93 | * exec-all : all PROT_READ user mappings are executable, except when
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| 94 | * backed by files on a noexec-filesystem.
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| 95 | * exec-none : only PROT_EXEC user mappings are executable.
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| 96 | * exec-stack: only the stack and PROT_EXEC user mappings are executable.
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| 97 | *
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| 98 | * *this column has no architectural effect: NX markings are ignored by
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| 99 | * hardware, but may have behavioral effects when "wants X" collides with
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| 100 | * "cannot be X" constraints in memory permission flags, as in
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| 101 | * https://lkml.kernel.org/r/[email protected]
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| 102 | *
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| 103 |
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| 104 | int arm_elf_read_implies_exec(int executable_stack)
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| 105 | {
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| 106 | if (executable_stack == EXSTACK_DEFAULT)
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| 107 | return 1;
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| 108 | if (cpu_architecture() < CPU_ARCH_ARMv6)
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| 109 | return 1;
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| 110 | return 0;
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| 111 | }
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| 112 | EXPORT_SYMBOL(arm_elf_read_implies_exec);
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| 113 |
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| 114 | #if defined(CONFIG_MMU) && defined(CONFIG_BINFMT_ELF_FDPIC)
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| 115 |
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| 116 | void elf_fdpic_arch_lay_out_mm(struct elf_fdpic_params *exec_params,
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| 117 | struct elf_fdpic_params *interp_params,
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| 118 | unsigned long *start_stack,
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| 119 | unsigned long *start_brk)
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| 120 | {
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| 121 | elf_set_personality(&exec_params->hdr);
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| 122 |
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| 123 | exec_params->load_addr = 0x8000;
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| 124 | interp_params->load_addr = ELF_ET_DYN_BASE;
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| 125 | *start_stack = TASK_SIZE - SZ_16M;
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| 126 |
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| 127 | if ((exec_params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) == ELF_FDPIC_FLAG_INDEPENDENT) {
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| 128 | exec_params->flags &= ~ELF_FDPIC_FLAG_ARRANGEMENT;
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| 129 | exec_params->flags |= ELF_FDPIC_FLAG_CONSTDISP;
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| 130 | }
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| 131 | }
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| 132 |
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| 133 | #endif
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