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16171bffc8
Alex Shi reported the pkey macros above arch_set_user_pkey_access() to be unused. They are unused, and even refer to a nonexistent CONFIG option. But, they might have served a good use, which was to ensure that the code does not try to set values that would not fit in the PKRU register. As it stands, a too-large 'pkey' value would be likely to silently overflow the u32 new_pkru_bits. Add a check to look for overflows. Also add a comment to remind any future developer to closely examine the types used to store pkey values if arch_max_pkey() ever changes. This boots and passes the x86 pkey selftests. Reported-by: Alex Shi <alex.shi@linux.alibaba.com> Signed-off-by: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20200122165346.AD4DA150@viggo.jf.intel.com
138 lines
3.5 KiB
C
138 lines
3.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_PKEYS_H
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#define _ASM_X86_PKEYS_H
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#define ARCH_DEFAULT_PKEY 0
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/*
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* If more than 16 keys are ever supported, a thorough audit
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* will be necessary to ensure that the types that store key
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* numbers and masks have sufficient capacity.
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*/
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#define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1)
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extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
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unsigned long init_val);
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static inline bool arch_pkeys_enabled(void)
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{
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return boot_cpu_has(X86_FEATURE_OSPKE);
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}
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/*
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* Try to dedicate one of the protection keys to be used as an
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* execute-only protection key.
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*/
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extern int __execute_only_pkey(struct mm_struct *mm);
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static inline int execute_only_pkey(struct mm_struct *mm)
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{
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if (!boot_cpu_has(X86_FEATURE_OSPKE))
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return ARCH_DEFAULT_PKEY;
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return __execute_only_pkey(mm);
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}
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extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
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int prot, int pkey);
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static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
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int prot, int pkey)
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{
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if (!boot_cpu_has(X86_FEATURE_OSPKE))
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return 0;
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return __arch_override_mprotect_pkey(vma, prot, pkey);
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}
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extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
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unsigned long init_val);
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#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3)
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#define mm_pkey_allocation_map(mm) (mm->context.pkey_allocation_map)
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#define mm_set_pkey_allocated(mm, pkey) do { \
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mm_pkey_allocation_map(mm) |= (1U << pkey); \
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} while (0)
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#define mm_set_pkey_free(mm, pkey) do { \
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mm_pkey_allocation_map(mm) &= ~(1U << pkey); \
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} while (0)
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static inline
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bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
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{
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/*
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* "Allocated" pkeys are those that have been returned
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* from pkey_alloc() or pkey 0 which is allocated
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* implicitly when the mm is created.
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*/
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if (pkey < 0)
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return false;
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if (pkey >= arch_max_pkey())
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return false;
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/*
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* The exec-only pkey is set in the allocation map, but
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* is not available to any of the user interfaces like
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* mprotect_pkey().
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*/
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if (pkey == mm->context.execute_only_pkey)
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return false;
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return mm_pkey_allocation_map(mm) & (1U << pkey);
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}
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/*
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* Returns a positive, 4-bit key on success, or -1 on failure.
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*/
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static inline
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int mm_pkey_alloc(struct mm_struct *mm)
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{
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/*
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* Note: this is the one and only place we make sure
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* that the pkey is valid as far as the hardware is
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* concerned. The rest of the kernel trusts that
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* only good, valid pkeys come out of here.
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*/
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u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1);
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int ret;
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/*
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* Are we out of pkeys? We must handle this specially
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* because ffz() behavior is undefined if there are no
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* zeros.
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*/
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if (mm_pkey_allocation_map(mm) == all_pkeys_mask)
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return -1;
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ret = ffz(mm_pkey_allocation_map(mm));
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mm_set_pkey_allocated(mm, ret);
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return ret;
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}
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static inline
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int mm_pkey_free(struct mm_struct *mm, int pkey)
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{
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if (!mm_pkey_is_allocated(mm, pkey))
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return -EINVAL;
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mm_set_pkey_free(mm, pkey);
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return 0;
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}
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extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
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unsigned long init_val);
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extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
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unsigned long init_val);
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extern void copy_init_pkru_to_fpregs(void);
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static inline int vma_pkey(struct vm_area_struct *vma)
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{
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unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
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VM_PKEY_BIT2 | VM_PKEY_BIT3;
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return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
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}
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#endif /*_ASM_X86_PKEYS_H */
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