| 1 | |
| 2 |
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| 3 | #include <linux/capability.h>
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| 4 | #include <linux/cpu.h>
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| 5 | #include <linux/init.h>
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| 6 | #include <linux/prctl.h>
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| 7 | #include <linux/sched.h>
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| 8 |
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| 9 | #include <asm/cpu_has_feature.h>
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| 10 | #include <asm/cputable.h>
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| 11 | #include <asm/processor.h>
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| 12 | #include <asm/reg.h>
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| 13 |
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| 14 | static int __init init_task_dexcr(void)
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| 15 | {
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| 16 | if (!early_cpu_has_feature(CPU_FTR_ARCH_31))
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| 17 | return 0;
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| 18 |
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| 19 | current->thread.dexcr_onexec = mfspr(SPRN_DEXCR);
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| 20 |
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| 21 | return 0;
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| 22 | }
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| 23 | early_initcall(init_task_dexcr)
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| 24 |
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| 25 |
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| 26 | #define DEXCR_PRCTL_EDITABLE ( \
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| 27 | DEXCR_PR_IBRTPD | \
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| 28 | DEXCR_PR_SRAPD | \
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| 29 | DEXCR_PR_NPHIE)
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| 30 |
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| 31 | static int prctl_to_aspect(unsigned long which, unsigned int *aspect)
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| 32 | {
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| 33 | switch (which) {
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| 34 | case PR_PPC_DEXCR_SBHE:
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| 35 | *aspect = DEXCR_PR_SBHE;
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| 36 | break;
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| 37 | case PR_PPC_DEXCR_IBRTPD:
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| 38 | *aspect = DEXCR_PR_IBRTPD;
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| 39 | break;
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| 40 | case PR_PPC_DEXCR_SRAPD:
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| 41 | *aspect = DEXCR_PR_SRAPD;
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| 42 | break;
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| 43 | case PR_PPC_DEXCR_NPHIE:
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| 44 | *aspect = DEXCR_PR_NPHIE;
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| 45 | break;
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| 46 | default:
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| 47 | return -ENODEV;
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| 48 | }
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| 49 |
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| 50 | return 0;
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| 51 | }
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| 52 |
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| 53 | int get_dexcr_prctl(struct task_struct *task, unsigned long which)
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| 54 | {
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| 55 | unsigned int aspect;
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| 56 | int ret;
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| 57 |
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| 58 | ret = prctl_to_aspect(which, &aspect);
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| 59 | if (ret)
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| 60 | return ret;
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| 61 |
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| 62 | if (aspect & DEXCR_PRCTL_EDITABLE)
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| 63 | ret |= PR_PPC_DEXCR_CTRL_EDITABLE;
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| 64 |
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| 65 | if (aspect & mfspr(SPRN_DEXCR))
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| 66 | ret |= PR_PPC_DEXCR_CTRL_SET;
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| 67 | else
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| 68 | ret |= PR_PPC_DEXCR_CTRL_CLEAR;
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| 69 |
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| 70 | if (aspect & task->thread.dexcr_onexec)
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| 71 | ret |= PR_PPC_DEXCR_CTRL_SET_ONEXEC;
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| 72 | else
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| 73 | ret |= PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC;
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| 74 |
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| 75 | return ret;
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| 76 | }
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| 77 |
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| 78 | int set_dexcr_prctl(struct task_struct *task, unsigned long which, unsigned long ctrl)
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| 79 | {
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| 80 | unsigned long dexcr;
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| 81 | unsigned int aspect;
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| 82 | int err = 0;
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| 83 |
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| 84 | err = prctl_to_aspect(which, &aspect);
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| 85 | if (err)
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| 86 | return err;
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| 87 |
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| 88 | if (!(aspect & DEXCR_PRCTL_EDITABLE))
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| 89 | return -EPERM;
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| 90 |
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| 91 | if (ctrl & ~PR_PPC_DEXCR_CTRL_MASK)
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| 92 | return -EINVAL;
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| 93 |
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| 94 | if (ctrl & PR_PPC_DEXCR_CTRL_SET && ctrl & PR_PPC_DEXCR_CTRL_CLEAR)
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| 95 | return -EINVAL;
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| 96 |
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| 97 | if (ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC && ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC)
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| 98 | return -EINVAL;
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| 99 |
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| 100 | |
| 101 | * We do not want an unprivileged process being able to disable
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| 102 | * a setuid process's hash check instructions
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| 103 |
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| 104 | if (aspect == DEXCR_PR_NPHIE &&
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| 105 | ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC &&
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| 106 | !capable(CAP_SYS_ADMIN))
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| 107 | return -EPERM;
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| 108 |
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| 109 | dexcr = mfspr(SPRN_DEXCR);
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| 110 |
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| 111 | if (ctrl & PR_PPC_DEXCR_CTRL_SET)
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| 112 | dexcr |= aspect;
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| 113 | else if (ctrl & PR_PPC_DEXCR_CTRL_CLEAR)
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| 114 | dexcr &= ~aspect;
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| 115 |
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| 116 | if (ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC)
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| 117 | task->thread.dexcr_onexec |= aspect;
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| 118 | else if (ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC)
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| 119 | task->thread.dexcr_onexec &= ~aspect;
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| 120 |
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| 121 | mtspr(SPRN_DEXCR, dexcr);
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| 122 |
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| 123 | return 0;
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| 124 | }
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