diff options
Diffstat (limited to 'arch/arm64/kernel/vdso.c')
| -rw-r--r-- | arch/arm64/kernel/vdso.c | 136 |
1 files changed, 123 insertions, 13 deletions
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index e546df0efefb..d4202a32abc9 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -18,6 +18,7 @@ #include <linux/sched.h> #include <linux/signal.h> #include <linux/slab.h> +#include <linux/time_namespace.h> #include <linux/timekeeper_internal.h> #include <linux/vmalloc.h> #include <vdso/datapage.h> @@ -40,6 +41,12 @@ enum vdso_abi { #endif /* CONFIG_COMPAT_VDSO */ }; +enum vvar_pages { + VVAR_DATA_PAGE_OFFSET, + VVAR_TIMENS_PAGE_OFFSET, + VVAR_NR_PAGES, +}; + struct vdso_abi_info { const char *name; const char *vdso_code_start; @@ -107,25 +114,122 @@ static int __vdso_init(enum vdso_abi abi) vdso_info[abi].vdso_code_start) >> PAGE_SHIFT; - /* Allocate the vDSO pagelist, plus a page for the data. */ - vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages + 1, + vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages, sizeof(struct page *), GFP_KERNEL); if (vdso_pagelist == NULL) return -ENOMEM; - /* Grab the vDSO data page. */ - vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data)); - - /* Grab the vDSO code pages. */ pfn = sym_to_pfn(vdso_info[abi].vdso_code_start); for (i = 0; i < vdso_info[abi].vdso_pages; i++) - vdso_pagelist[i + 1] = pfn_to_page(pfn + i); + vdso_pagelist[i] = pfn_to_page(pfn + i); + + vdso_info[abi].cm->pages = vdso_pagelist; + + return 0; +} + +#ifdef CONFIG_TIME_NS +struct vdso_data *arch_get_vdso_data(void *vvar_page) +{ + return (struct vdso_data *)(vvar_page); +} + +/* + * The vvar mapping contains data for a specific time namespace, so when a task + * changes namespace we must unmap its vvar data for the old namespace. + * Subsequent faults will map in data for the new namespace. + * + * For more details see timens_setup_vdso_data(). + */ +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) +{ + struct mm_struct *mm = task->mm; + struct vm_area_struct *vma; + + mmap_read_lock(mm); + + for (vma = mm->mmap; vma; vma = vma->vm_next) { + unsigned long size = vma->vm_end - vma->vm_start; - vdso_info[abi].dm->pages = &vdso_pagelist[0]; - vdso_info[abi].cm->pages = &vdso_pagelist[1]; + if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_AA64].dm)) + zap_page_range(vma, vma->vm_start, size); +#ifdef CONFIG_COMPAT_VDSO + if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_AA32].dm)) + zap_page_range(vma, vma->vm_start, size); +#endif + } + + mmap_read_unlock(mm); + return 0; +} + +static struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + if (likely(vma->vm_mm == current->mm)) + return current->nsproxy->time_ns->vvar_page; + + /* + * VM_PFNMAP | VM_IO protect .fault() handler from being called + * through interfaces like /proc/$pid/mem or + * process_vm_{readv,writev}() as long as there's no .access() + * in special_mapping_vmops. + * For more details check_vma_flags() and __access_remote_vm() + */ + WARN(1, "vvar_page accessed remotely"); + + return NULL; +} +#else +static struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + return NULL; +} +#endif + +static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, + struct vm_area_struct *vma, struct vm_fault *vmf) +{ + struct page *timens_page = find_timens_vvar_page(vma); + unsigned long pfn; + + switch (vmf->pgoff) { + case VVAR_DATA_PAGE_OFFSET: + if (timens_page) + pfn = page_to_pfn(timens_page); + else + pfn = sym_to_pfn(vdso_data); + break; +#ifdef CONFIG_TIME_NS + case VVAR_TIMENS_PAGE_OFFSET: + /* + * If a task belongs to a time namespace then a namespace + * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and + * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET + * offset. + * See also the comment near timens_setup_vdso_data(). + */ + if (!timens_page) + return VM_FAULT_SIGBUS; + pfn = sym_to_pfn(vdso_data); + break; +#endif /* CONFIG_TIME_NS */ + default: + return VM_FAULT_SIGBUS; + } + + return vmf_insert_pfn(vma, vmf->address, pfn); +} + +static int vvar_mremap(const struct vm_special_mapping *sm, + struct vm_area_struct *new_vma) +{ + unsigned long new_size = new_vma->vm_end - new_vma->vm_start; + + if (new_size != VVAR_NR_PAGES * PAGE_SIZE) + return -EINVAL; return 0; } @@ -139,9 +243,11 @@ static int __setup_additional_pages(enum vdso_abi abi, unsigned long gp_flags = 0; void *ret; + BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES); + vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT; /* Be sure to map the data page */ - vdso_mapping_len = vdso_text_len + PAGE_SIZE; + vdso_mapping_len = vdso_text_len + VVAR_NR_PAGES * PAGE_SIZE; vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); if (IS_ERR_VALUE(vdso_base)) { @@ -149,8 +255,8 @@ static int __setup_additional_pages(enum vdso_abi abi, goto up_fail; } - ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE, - VM_READ|VM_MAYREAD, + ret = _install_special_mapping(mm, vdso_base, VVAR_NR_PAGES * PAGE_SIZE, + VM_READ|VM_MAYREAD|VM_PFNMAP, vdso_info[abi].dm); if (IS_ERR(ret)) goto up_fail; @@ -158,7 +264,7 @@ static int __setup_additional_pages(enum vdso_abi abi, if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) && system_supports_bti()) gp_flags = VM_ARM64_BTI; - vdso_base += PAGE_SIZE; + vdso_base += VVAR_NR_PAGES * PAGE_SIZE; mm->context.vdso = (void *)vdso_base; ret = _install_special_mapping(mm, vdso_base, vdso_text_len, VM_READ|VM_EXEC|gp_flags| @@ -206,6 +312,8 @@ static struct vm_special_mapping aarch32_vdso_maps[] = { #ifdef CONFIG_COMPAT_VDSO [AA32_MAP_VVAR] = { .name = "[vvar]", + .fault = vvar_fault, + .mremap = vvar_mremap, }, [AA32_MAP_VDSO] = { .name = "[vdso]", @@ -371,6 +479,8 @@ enum aarch64_map { static struct vm_special_mapping aarch64_vdso_maps[] __ro_after_init = { [AA64_MAP_VVAR] = { .name = "[vvar]", + .fault = vvar_fault, + .mremap = vvar_mremap, }, [AA64_MAP_VDSO] = { .name = "[vdso]", |