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44b04912fa
MPX (without MAWA extension) cannot handle addresses above 47 bits, so we need to make sure that MPX cannot be enabled if we already have a VMA above the boundary and forbid creating such VMAs once MPX is enabled. The patch implements mpx_unmapped_area_check() which is called from all variants of get_unmapped_area() to check if the requested address fits mpx. On enabling MPX, we check if we already have any vma above 47-bit boundary and forbit the enabling if we do. As long as DEFAULT_MAP_WINDOW is equal to TASK_SIZE_MAX, the change is nop. It will change when we allow userspace to have mappings above 47-bits. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20170716225954.74185-6-kirill.shutemov@linux.intel.com [ Readability edits. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
108 lines
2.9 KiB
C
108 lines
2.9 KiB
C
#ifndef _ASM_X86_MPX_H
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#define _ASM_X86_MPX_H
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#include <linux/types.h>
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#include <linux/mm_types.h>
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#include <asm/ptrace.h>
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#include <asm/insn.h>
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/*
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* NULL is theoretically a valid place to put the bounds
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* directory, so point this at an invalid address.
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*/
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#define MPX_INVALID_BOUNDS_DIR ((void __user *)-1)
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#define MPX_BNDCFG_ENABLE_FLAG 0x1
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#define MPX_BD_ENTRY_VALID_FLAG 0x1
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/*
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* The upper 28 bits [47:20] of the virtual address in 64-bit
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* are used to index into bounds directory (BD).
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*
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* The directory is 2G (2^31) in size, and with 8-byte entries
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* it has 2^28 entries.
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*/
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#define MPX_BD_SIZE_BYTES_64 (1UL<<31)
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#define MPX_BD_ENTRY_BYTES_64 8
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#define MPX_BD_NR_ENTRIES_64 (MPX_BD_SIZE_BYTES_64/MPX_BD_ENTRY_BYTES_64)
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/*
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* The 32-bit directory is 4MB (2^22) in size, and with 4-byte
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* entries it has 2^20 entries.
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*/
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#define MPX_BD_SIZE_BYTES_32 (1UL<<22)
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#define MPX_BD_ENTRY_BYTES_32 4
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#define MPX_BD_NR_ENTRIES_32 (MPX_BD_SIZE_BYTES_32/MPX_BD_ENTRY_BYTES_32)
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/*
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* A 64-bit table is 4MB total in size, and an entry is
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* 4 64-bit pointers in size.
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*/
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#define MPX_BT_SIZE_BYTES_64 (1UL<<22)
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#define MPX_BT_ENTRY_BYTES_64 32
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#define MPX_BT_NR_ENTRIES_64 (MPX_BT_SIZE_BYTES_64/MPX_BT_ENTRY_BYTES_64)
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/*
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* A 32-bit table is 16kB total in size, and an entry is
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* 4 32-bit pointers in size.
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*/
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#define MPX_BT_SIZE_BYTES_32 (1UL<<14)
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#define MPX_BT_ENTRY_BYTES_32 16
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#define MPX_BT_NR_ENTRIES_32 (MPX_BT_SIZE_BYTES_32/MPX_BT_ENTRY_BYTES_32)
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#define MPX_BNDSTA_TAIL 2
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#define MPX_BNDCFG_TAIL 12
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#define MPX_BNDSTA_ADDR_MASK (~((1UL<<MPX_BNDSTA_TAIL)-1))
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#define MPX_BNDCFG_ADDR_MASK (~((1UL<<MPX_BNDCFG_TAIL)-1))
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#define MPX_BNDSTA_ERROR_CODE 0x3
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#ifdef CONFIG_X86_INTEL_MPX
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siginfo_t *mpx_generate_siginfo(struct pt_regs *regs);
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int mpx_handle_bd_fault(void);
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static inline int kernel_managing_mpx_tables(struct mm_struct *mm)
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{
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return (mm->context.bd_addr != MPX_INVALID_BOUNDS_DIR);
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}
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static inline void mpx_mm_init(struct mm_struct *mm)
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{
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/*
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* NULL is theoretically a valid place to put the bounds
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* directory, so point this at an invalid address.
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*/
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mm->context.bd_addr = MPX_INVALID_BOUNDS_DIR;
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}
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void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
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unsigned long start, unsigned long end);
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unsigned long mpx_unmapped_area_check(unsigned long addr, unsigned long len,
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unsigned long flags);
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#else
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static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs)
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{
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return NULL;
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}
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static inline int mpx_handle_bd_fault(void)
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{
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return -EINVAL;
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}
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static inline int kernel_managing_mpx_tables(struct mm_struct *mm)
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{
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return 0;
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}
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static inline void mpx_mm_init(struct mm_struct *mm)
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{
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}
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static inline void mpx_notify_unmap(struct mm_struct *mm,
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struct vm_area_struct *vma,
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unsigned long start, unsigned long end)
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{
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}
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static inline unsigned long mpx_unmapped_area_check(unsigned long addr,
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unsigned long len, unsigned long flags)
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{
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return addr;
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}
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#endif /* CONFIG_X86_INTEL_MPX */
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#endif /* _ASM_X86_MPX_H */
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