Book a Demo!
CoCalc Logo Icon
StoreFeaturesDocsShareSupportNewsAboutPoliciesSign UpSign In
torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/powerpc/kernel/dexcr.c
26444 views
1
// SPDX-License-Identifier: GPL-2.0-or-later

2


3
#include <linux/capability.h>

4
#include <linux/cpu.h>

5
#include <linux/init.h>

6
#include <linux/prctl.h>

7
#include <linux/sched.h>

8


9
#include <asm/cpu_has_feature.h>

10
#include <asm/cputable.h>

11
#include <asm/processor.h>

12
#include <asm/reg.h>

13


14
static int __init init_task_dexcr(void)

15
{

16
	if (!early_cpu_has_feature(CPU_FTR_ARCH_31))

17
		return 0;

18


19
	current->thread.dexcr_onexec = mfspr(SPRN_DEXCR);

20


21
	return 0;

22
}

23
early_initcall(init_task_dexcr)

24


25
/* Allow thread local configuration of these by default */

26
#define DEXCR_PRCTL_EDITABLE ( \

27
	DEXCR_PR_IBRTPD | \

28
	DEXCR_PR_SRAPD | \

29
	DEXCR_PR_NPHIE)

30


31
static int prctl_to_aspect(unsigned long which, unsigned int *aspect)

32
{

33
	switch (which) {

34
	case PR_PPC_DEXCR_SBHE:

35
		*aspect = DEXCR_PR_SBHE;

36
		break;

37
	case PR_PPC_DEXCR_IBRTPD:

38
		*aspect = DEXCR_PR_IBRTPD;

39
		break;

40
	case PR_PPC_DEXCR_SRAPD:

41
		*aspect = DEXCR_PR_SRAPD;

42
		break;

43
	case PR_PPC_DEXCR_NPHIE:

44
		*aspect = DEXCR_PR_NPHIE;

45
		break;

46
	default:

47
		return -ENODEV;

48
	}

49


50
	return 0;

51
}

52


53
int get_dexcr_prctl(struct task_struct *task, unsigned long which)

54
{

55
	unsigned int aspect;

56
	int ret;

57


58
	ret = prctl_to_aspect(which, &aspect);

59
	if (ret)

60
		return ret;

61


62
	if (aspect & DEXCR_PRCTL_EDITABLE)

63
		ret |= PR_PPC_DEXCR_CTRL_EDITABLE;

64


65
	if (aspect & mfspr(SPRN_DEXCR))

66
		ret |= PR_PPC_DEXCR_CTRL_SET;

67
	else

68
		ret |= PR_PPC_DEXCR_CTRL_CLEAR;

69


70
	if (aspect & task->thread.dexcr_onexec)

71
		ret |= PR_PPC_DEXCR_CTRL_SET_ONEXEC;

72
	else

73
		ret |= PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC;

74


75
	return ret;

76
}

77


78
int set_dexcr_prctl(struct task_struct *task, unsigned long which, unsigned long ctrl)

79
{

80
	unsigned long dexcr;

81
	unsigned int aspect;

82
	int err = 0;

83


84
	err = prctl_to_aspect(which, &aspect);

85
	if (err)

86
		return err;

87


88
	if (!(aspect & DEXCR_PRCTL_EDITABLE))

89
		return -EPERM;

90


91
	if (ctrl & ~PR_PPC_DEXCR_CTRL_MASK)

92
		return -EINVAL;

93


94
	if (ctrl & PR_PPC_DEXCR_CTRL_SET && ctrl & PR_PPC_DEXCR_CTRL_CLEAR)

95
		return -EINVAL;

96


97
	if (ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC && ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC)

98
		return -EINVAL;

99


100
	/*

101
	 * We do not want an unprivileged process being able to disable

102
	 * a setuid process's hash check instructions

103
	 */

104
	if (aspect == DEXCR_PR_NPHIE &&

105
	    ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC &&

106
	    !capable(CAP_SYS_ADMIN))

107
		return -EPERM;

108


109
	dexcr = mfspr(SPRN_DEXCR);

110


111
	if (ctrl & PR_PPC_DEXCR_CTRL_SET)

112
		dexcr |= aspect;

113
	else if (ctrl & PR_PPC_DEXCR_CTRL_CLEAR)

114
		dexcr &= ~aspect;

115


116
	if (ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC)

117
		task->thread.dexcr_onexec |= aspect;

118
	else if (ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC)

119
		task->thread.dexcr_onexec &= ~aspect;

120


121
	mtspr(SPRN_DEXCR, dexcr);

122


123
	return 0;

124
}

125


126