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467 lines
11 KiB
467 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* VDSO implementations. |
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* |
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* Copyright (C) 2012 ARM Limited |
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* |
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* Author: Will Deacon <[email protected]> |
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*/ |
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#include <linux/cache.h> |
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#include <linux/clocksource.h> |
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#include <linux/elf.h> |
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#include <linux/err.h> |
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#include <linux/errno.h> |
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#include <linux/gfp.h> |
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#include <linux/kernel.h> |
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#include <linux/mm.h> |
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#include <linux/sched.h> |
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#include <linux/signal.h> |
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#include <linux/slab.h> |
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#include <linux/time_namespace.h> |
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#include <linux/timekeeper_internal.h> |
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#include <linux/vmalloc.h> |
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#include <vdso/datapage.h> |
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#include <vdso/helpers.h> |
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#include <vdso/vsyscall.h> |
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#include <asm/cacheflush.h> |
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#include <asm/signal32.h> |
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#include <asm/vdso.h> |
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extern char vdso_start[], vdso_end[]; |
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extern char vdso32_start[], vdso32_end[]; |
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enum vdso_abi { |
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VDSO_ABI_AA64, |
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VDSO_ABI_AA32, |
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}; |
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enum vvar_pages { |
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VVAR_DATA_PAGE_OFFSET, |
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VVAR_TIMENS_PAGE_OFFSET, |
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VVAR_NR_PAGES, |
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}; |
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struct vdso_abi_info { |
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const char *name; |
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const char *vdso_code_start; |
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const char *vdso_code_end; |
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unsigned long vdso_pages; |
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/* Data Mapping */ |
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struct vm_special_mapping *dm; |
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/* Code Mapping */ |
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struct vm_special_mapping *cm; |
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}; |
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static struct vdso_abi_info vdso_info[] __ro_after_init = { |
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[VDSO_ABI_AA64] = { |
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.name = "vdso", |
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.vdso_code_start = vdso_start, |
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.vdso_code_end = vdso_end, |
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}, |
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#ifdef CONFIG_COMPAT_VDSO |
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[VDSO_ABI_AA32] = { |
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.name = "vdso32", |
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.vdso_code_start = vdso32_start, |
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.vdso_code_end = vdso32_end, |
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}, |
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#endif /* CONFIG_COMPAT_VDSO */ |
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}; |
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/* |
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* The vDSO data page. |
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*/ |
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static union { |
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struct vdso_data data[CS_BASES]; |
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u8 page[PAGE_SIZE]; |
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} vdso_data_store __page_aligned_data; |
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struct vdso_data *vdso_data = vdso_data_store.data; |
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static int vdso_mremap(const struct vm_special_mapping *sm, |
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struct vm_area_struct *new_vma) |
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{ |
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current->mm->context.vdso = (void *)new_vma->vm_start; |
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return 0; |
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} |
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static int __vdso_init(enum vdso_abi abi) |
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{ |
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int i; |
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struct page **vdso_pagelist; |
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unsigned long pfn; |
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if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4)) { |
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pr_err("vDSO is not a valid ELF object!\n"); |
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return -EINVAL; |
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} |
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vdso_info[abi].vdso_pages = ( |
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vdso_info[abi].vdso_code_end - |
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vdso_info[abi].vdso_code_start) >> |
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PAGE_SHIFT; |
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vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages, |
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sizeof(struct page *), |
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GFP_KERNEL); |
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if (vdso_pagelist == NULL) |
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return -ENOMEM; |
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/* Grab the vDSO code pages. */ |
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pfn = sym_to_pfn(vdso_info[abi].vdso_code_start); |
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for (i = 0; i < vdso_info[abi].vdso_pages; i++) |
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vdso_pagelist[i] = pfn_to_page(pfn + i); |
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vdso_info[abi].cm->pages = vdso_pagelist; |
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return 0; |
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} |
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#ifdef CONFIG_TIME_NS |
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struct vdso_data *arch_get_vdso_data(void *vvar_page) |
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{ |
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return (struct vdso_data *)(vvar_page); |
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} |
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/* |
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* The vvar mapping contains data for a specific time namespace, so when a task |
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* changes namespace we must unmap its vvar data for the old namespace. |
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* Subsequent faults will map in data for the new namespace. |
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* |
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* For more details see timens_setup_vdso_data(). |
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*/ |
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int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) |
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{ |
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struct mm_struct *mm = task->mm; |
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struct vm_area_struct *vma; |
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mmap_read_lock(mm); |
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for (vma = mm->mmap; vma; vma = vma->vm_next) { |
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unsigned long size = vma->vm_end - vma->vm_start; |
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if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_AA64].dm)) |
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zap_page_range(vma, vma->vm_start, size); |
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#ifdef CONFIG_COMPAT_VDSO |
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if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_AA32].dm)) |
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zap_page_range(vma, vma->vm_start, size); |
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#endif |
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} |
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mmap_read_unlock(mm); |
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return 0; |
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} |
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static struct page *find_timens_vvar_page(struct vm_area_struct *vma) |
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{ |
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if (likely(vma->vm_mm == current->mm)) |
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return current->nsproxy->time_ns->vvar_page; |
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/* |
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* VM_PFNMAP | VM_IO protect .fault() handler from being called |
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* through interfaces like /proc/$pid/mem or |
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* process_vm_{readv,writev}() as long as there's no .access() |
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* in special_mapping_vmops. |
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* For more details check_vma_flags() and __access_remote_vm() |
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*/ |
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WARN(1, "vvar_page accessed remotely"); |
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return NULL; |
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} |
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#else |
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static struct page *find_timens_vvar_page(struct vm_area_struct *vma) |
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{ |
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return NULL; |
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} |
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#endif |
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static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, |
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struct vm_area_struct *vma, struct vm_fault *vmf) |
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{ |
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struct page *timens_page = find_timens_vvar_page(vma); |
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unsigned long pfn; |
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switch (vmf->pgoff) { |
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case VVAR_DATA_PAGE_OFFSET: |
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if (timens_page) |
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pfn = page_to_pfn(timens_page); |
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else |
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pfn = sym_to_pfn(vdso_data); |
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break; |
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#ifdef CONFIG_TIME_NS |
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case VVAR_TIMENS_PAGE_OFFSET: |
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/* |
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* If a task belongs to a time namespace then a namespace |
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* specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and |
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* the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET |
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* offset. |
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* See also the comment near timens_setup_vdso_data(). |
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*/ |
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if (!timens_page) |
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return VM_FAULT_SIGBUS; |
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pfn = sym_to_pfn(vdso_data); |
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break; |
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#endif /* CONFIG_TIME_NS */ |
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default: |
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return VM_FAULT_SIGBUS; |
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} |
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return vmf_insert_pfn(vma, vmf->address, pfn); |
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} |
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static int __setup_additional_pages(enum vdso_abi abi, |
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struct mm_struct *mm, |
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struct linux_binprm *bprm, |
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int uses_interp) |
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{ |
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unsigned long vdso_base, vdso_text_len, vdso_mapping_len; |
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unsigned long gp_flags = 0; |
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void *ret; |
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BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES); |
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vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT; |
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/* Be sure to map the data page */ |
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vdso_mapping_len = vdso_text_len + VVAR_NR_PAGES * PAGE_SIZE; |
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vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); |
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if (IS_ERR_VALUE(vdso_base)) { |
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ret = ERR_PTR(vdso_base); |
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goto up_fail; |
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} |
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ret = _install_special_mapping(mm, vdso_base, VVAR_NR_PAGES * PAGE_SIZE, |
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VM_READ|VM_MAYREAD|VM_PFNMAP, |
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vdso_info[abi].dm); |
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if (IS_ERR(ret)) |
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goto up_fail; |
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if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) && system_supports_bti()) |
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gp_flags = VM_ARM64_BTI; |
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vdso_base += VVAR_NR_PAGES * PAGE_SIZE; |
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mm->context.vdso = (void *)vdso_base; |
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ret = _install_special_mapping(mm, vdso_base, vdso_text_len, |
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VM_READ|VM_EXEC|gp_flags| |
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, |
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vdso_info[abi].cm); |
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if (IS_ERR(ret)) |
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goto up_fail; |
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return 0; |
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up_fail: |
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mm->context.vdso = NULL; |
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return PTR_ERR(ret); |
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} |
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#ifdef CONFIG_COMPAT |
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/* |
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* Create and map the vectors page for AArch32 tasks. |
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*/ |
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enum aarch32_map { |
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AA32_MAP_VECTORS, /* kuser helpers */ |
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AA32_MAP_SIGPAGE, |
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AA32_MAP_VVAR, |
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AA32_MAP_VDSO, |
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}; |
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static struct page *aarch32_vectors_page __ro_after_init; |
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static struct page *aarch32_sig_page __ro_after_init; |
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static struct vm_special_mapping aarch32_vdso_maps[] = { |
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[AA32_MAP_VECTORS] = { |
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.name = "[vectors]", /* ABI */ |
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.pages = &aarch32_vectors_page, |
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}, |
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[AA32_MAP_SIGPAGE] = { |
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.name = "[sigpage]", /* ABI */ |
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.pages = &aarch32_sig_page, |
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}, |
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[AA32_MAP_VVAR] = { |
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.name = "[vvar]", |
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.fault = vvar_fault, |
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}, |
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[AA32_MAP_VDSO] = { |
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.name = "[vdso]", |
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.mremap = vdso_mremap, |
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}, |
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}; |
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static int aarch32_alloc_kuser_vdso_page(void) |
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{ |
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extern char __kuser_helper_start[], __kuser_helper_end[]; |
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int kuser_sz = __kuser_helper_end - __kuser_helper_start; |
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unsigned long vdso_page; |
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if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) |
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return 0; |
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vdso_page = get_zeroed_page(GFP_ATOMIC); |
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if (!vdso_page) |
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return -ENOMEM; |
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memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start, |
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kuser_sz); |
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aarch32_vectors_page = virt_to_page(vdso_page); |
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flush_dcache_page(aarch32_vectors_page); |
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return 0; |
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} |
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static int aarch32_alloc_sigpage(void) |
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{ |
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extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[]; |
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int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start; |
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unsigned long sigpage; |
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sigpage = get_zeroed_page(GFP_ATOMIC); |
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if (!sigpage) |
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return -ENOMEM; |
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memcpy((void *)sigpage, __aarch32_sigret_code_start, sigret_sz); |
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aarch32_sig_page = virt_to_page(sigpage); |
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flush_dcache_page(aarch32_sig_page); |
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return 0; |
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} |
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static int __aarch32_alloc_vdso_pages(void) |
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{ |
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if (!IS_ENABLED(CONFIG_COMPAT_VDSO)) |
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return 0; |
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vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_maps[AA32_MAP_VVAR]; |
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vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO]; |
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return __vdso_init(VDSO_ABI_AA32); |
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} |
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static int __init aarch32_alloc_vdso_pages(void) |
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{ |
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int ret; |
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ret = __aarch32_alloc_vdso_pages(); |
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if (ret) |
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return ret; |
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ret = aarch32_alloc_sigpage(); |
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if (ret) |
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return ret; |
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return aarch32_alloc_kuser_vdso_page(); |
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} |
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arch_initcall(aarch32_alloc_vdso_pages); |
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static int aarch32_kuser_helpers_setup(struct mm_struct *mm) |
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{ |
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void *ret; |
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if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) |
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return 0; |
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/* |
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* Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's |
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* not safe to CoW the page containing the CPU exception vectors. |
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*/ |
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ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE, |
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VM_READ | VM_EXEC | |
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VM_MAYREAD | VM_MAYEXEC, |
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&aarch32_vdso_maps[AA32_MAP_VECTORS]); |
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return PTR_ERR_OR_ZERO(ret); |
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} |
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static int aarch32_sigreturn_setup(struct mm_struct *mm) |
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{ |
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unsigned long addr; |
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void *ret; |
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addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); |
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if (IS_ERR_VALUE(addr)) { |
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ret = ERR_PTR(addr); |
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goto out; |
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} |
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/* |
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* VM_MAYWRITE is required to allow gdb to Copy-on-Write and |
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* set breakpoints. |
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*/ |
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ret = _install_special_mapping(mm, addr, PAGE_SIZE, |
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VM_READ | VM_EXEC | VM_MAYREAD | |
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VM_MAYWRITE | VM_MAYEXEC, |
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&aarch32_vdso_maps[AA32_MAP_SIGPAGE]); |
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if (IS_ERR(ret)) |
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goto out; |
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mm->context.sigpage = (void *)addr; |
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out: |
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return PTR_ERR_OR_ZERO(ret); |
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} |
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int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
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{ |
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struct mm_struct *mm = current->mm; |
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int ret; |
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if (mmap_write_lock_killable(mm)) |
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return -EINTR; |
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ret = aarch32_kuser_helpers_setup(mm); |
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if (ret) |
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goto out; |
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if (IS_ENABLED(CONFIG_COMPAT_VDSO)) { |
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ret = __setup_additional_pages(VDSO_ABI_AA32, mm, bprm, |
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uses_interp); |
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if (ret) |
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goto out; |
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} |
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ret = aarch32_sigreturn_setup(mm); |
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out: |
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mmap_write_unlock(mm); |
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return ret; |
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} |
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#endif /* CONFIG_COMPAT */ |
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enum aarch64_map { |
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AA64_MAP_VVAR, |
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AA64_MAP_VDSO, |
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}; |
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static struct vm_special_mapping aarch64_vdso_maps[] __ro_after_init = { |
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[AA64_MAP_VVAR] = { |
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.name = "[vvar]", |
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.fault = vvar_fault, |
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}, |
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[AA64_MAP_VDSO] = { |
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.name = "[vdso]", |
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.mremap = vdso_mremap, |
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}, |
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}; |
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static int __init vdso_init(void) |
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{ |
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vdso_info[VDSO_ABI_AA64].dm = &aarch64_vdso_maps[AA64_MAP_VVAR]; |
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vdso_info[VDSO_ABI_AA64].cm = &aarch64_vdso_maps[AA64_MAP_VDSO]; |
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return __vdso_init(VDSO_ABI_AA64); |
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} |
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arch_initcall(vdso_init); |
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
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{ |
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struct mm_struct *mm = current->mm; |
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int ret; |
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if (mmap_write_lock_killable(mm)) |
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return -EINTR; |
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ret = __setup_additional_pages(VDSO_ABI_AA64, mm, bprm, uses_interp); |
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mmap_write_unlock(mm); |
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return ret; |
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}
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