diff options
Diffstat (limited to 'arch/arm64/mm/fault.c')
| -rw-r--r-- | arch/arm64/mm/fault.c | 77 |
1 files changed, 65 insertions, 12 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 8b281cf308b3..f590dc71ce99 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -375,7 +375,7 @@ static void __do_kernel_fault(unsigned long addr, unsigned long esr, * Are we prepared to handle this kernel fault? * We are almost certainly not prepared to handle instruction faults. */ - if (!is_el1_instruction_abort(esr) && fixup_exception(regs)) + if (!is_el1_instruction_abort(esr) && fixup_exception(regs, esr)) return; if (WARN_RATELIMIT(is_spurious_el1_translation_fault(addr, esr, regs), @@ -487,23 +487,43 @@ static void do_bad_area(unsigned long far, unsigned long esr, } } -static bool fault_from_pkey(unsigned long esr, struct vm_area_struct *vma, - unsigned int mm_flags) +static bool fault_from_pkey(struct vm_area_struct *vma, unsigned int mm_flags) { - unsigned long iss2 = ESR_ELx_ISS2(esr); - if (!system_supports_poe()) return false; - if (esr_fsc_is_permission_fault(esr) && (iss2 & ESR_ELx_Overlay)) - return true; - + /* + * We do not check whether an Overlay fault has occurred because we + * cannot make a decision based solely on its value: + * + * - If Overlay is set, a fault did occur due to POE, but it may be + * spurious in those cases where we update POR_EL0 without ISB (e.g. + * on context-switch). We would then need to manually check POR_EL0 + * against vma_pkey(vma), which is exactly what + * arch_vma_access_permitted() does. + * + * - If Overlay is not set, we may still need to report a pkey fault. + * This is the case if an access was made within a mapping but with no + * page mapped, and POR_EL0 forbids the access (according to + * vma_pkey()). Such access will result in a SIGSEGV regardless + * because core code checks arch_vma_access_permitted(), but in order + * to report the correct error code - SEGV_PKUERR - we must handle + * that case here. + */ return !arch_vma_access_permitted(vma, mm_flags & FAULT_FLAG_WRITE, mm_flags & FAULT_FLAG_INSTRUCTION, false); } +static bool is_gcs_fault(unsigned long esr) +{ + if (!esr_is_data_abort(esr)) + return false; + + return ESR_ELx_ISS2(esr) & ESR_ELx_GCS; +} + static bool is_el0_instruction_abort(unsigned long esr) { return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW; @@ -518,6 +538,23 @@ static bool is_write_abort(unsigned long esr) return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM); } +static bool is_invalid_gcs_access(struct vm_area_struct *vma, u64 esr) +{ + if (!system_supports_gcs()) + return false; + + if (unlikely(is_gcs_fault(esr))) { + /* GCS accesses must be performed on a GCS page */ + if (!(vma->vm_flags & VM_SHADOW_STACK)) + return true; + } else if (unlikely(vma->vm_flags & VM_SHADOW_STACK)) { + /* Only GCS operations can write to a GCS page */ + return esr_is_data_abort(esr) && is_write_abort(esr); + } + + return false; +} + static int __kprobes do_page_fault(unsigned long far, unsigned long esr, struct pt_regs *regs) { @@ -554,6 +591,14 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, /* It was exec fault */ vm_flags = VM_EXEC; mm_flags |= FAULT_FLAG_INSTRUCTION; + } else if (is_gcs_fault(esr)) { + /* + * The GCS permission on a page implies both read and + * write so always handle any GCS fault as a write fault, + * we need to trigger CoW even for GCS reads. + */ + vm_flags = VM_WRITE; + mm_flags |= FAULT_FLAG_WRITE; } else if (is_write_abort(esr)) { /* It was write fault */ vm_flags = VM_WRITE; @@ -573,7 +618,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, die_kernel_fault("execution of user memory", addr, esr, regs); - if (!search_exception_tables(regs->pc)) + if (!insn_may_access_user(regs->pc, esr)) die_kernel_fault("access to user memory outside uaccess routines", addr, esr, regs); } @@ -587,6 +632,13 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, if (!vma) goto lock_mmap; + if (is_invalid_gcs_access(vma, esr)) { + vma_end_read(vma); + fault = 0; + si_code = SEGV_ACCERR; + goto bad_area; + } + if (!(vma->vm_flags & vm_flags)) { vma_end_read(vma); fault = 0; @@ -595,7 +647,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, goto bad_area; } - if (fault_from_pkey(esr, vma, mm_flags)) { + if (fault_from_pkey(vma, mm_flags)) { pkey = vma_pkey(vma); vma_end_read(vma); fault = 0; @@ -639,7 +691,7 @@ retry: goto bad_area; } - if (fault_from_pkey(esr, vma, mm_flags)) { + if (fault_from_pkey(vma, mm_flags)) { pkey = vma_pkey(vma); mmap_read_unlock(mm); fault = 0; @@ -786,6 +838,7 @@ static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs) */ siaddr = untagged_addr(far); } + add_taint(TAINT_MACHINE_CHECK, LOCKDEP_STILL_OK); arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr); return 0; @@ -983,7 +1036,7 @@ struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, if (vma->vm_flags & VM_MTE) flags |= __GFP_ZEROTAGS; - return vma_alloc_folio(flags, 0, vma, vaddr, false); + return vma_alloc_folio(flags, 0, vma, vaddr); } void tag_clear_highpage(struct page *page) |