diff options
Diffstat (limited to 'arch/s390/kernel/vdso.c')
-rw-r--r-- | arch/s390/kernel/vdso.c | 58 |
1 files changed, 52 insertions, 6 deletions
diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c index 99694260cac9..3105ca5bd470 100644 --- a/arch/s390/kernel/vdso.c +++ b/arch/s390/kernel/vdso.c @@ -16,6 +16,7 @@ #include <linux/slab.h> #include <linux/smp.h> #include <linux/time_namespace.h> +#include <linux/random.h> #include <vdso/datapage.h> #include <asm/vdso.h> @@ -68,10 +69,11 @@ static struct page *find_timens_vvar_page(struct vm_area_struct *vma) int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) { struct mm_struct *mm = task->mm; + VMA_ITERATOR(vmi, mm, 0); struct vm_area_struct *vma; mmap_read_lock(mm); - for (vma = mm->mmap; vma; vma = vma->vm_next) { + for_each_vma(vmi, vma) { unsigned long size = vma->vm_end - vma->vm_start; if (!vma_is_special_mapping(vma, &vvar_mapping)) @@ -160,10 +162,9 @@ int vdso_getcpu_init(void) } early_initcall(vdso_getcpu_init); /* Must be called before SMP init */ -int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) +static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len) { - unsigned long vdso_text_len, vdso_mapping_len; - unsigned long vvar_start, vdso_text_start; + unsigned long vvar_start, vdso_text_start, vdso_text_len; struct vm_special_mapping *vdso_mapping; struct mm_struct *mm = current->mm; struct vm_area_struct *vma; @@ -180,8 +181,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) vdso_text_len = vdso64_end - vdso64_start; vdso_mapping = &vdso64_mapping; } - vdso_mapping_len = vdso_text_len + VVAR_NR_PAGES * PAGE_SIZE; - vvar_start = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); + vvar_start = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0); rc = vvar_start; if (IS_ERR_VALUE(vvar_start)) goto out; @@ -210,6 +210,52 @@ out: return rc; } +static unsigned long vdso_addr(unsigned long start, unsigned long len) +{ + unsigned long addr, end, offset; + + /* + * Round up the start address. It can start out unaligned as a result + * of stack start randomization. + */ + start = PAGE_ALIGN(start); + + /* Round the lowest possible end address up to a PMD boundary. */ + end = (start + len + PMD_SIZE - 1) & PMD_MASK; + if (end >= VDSO_BASE) + end = VDSO_BASE; + end -= len; + + if (end > start) { + offset = prandom_u32_max(((end - start) >> PAGE_SHIFT) + 1); + addr = start + (offset << PAGE_SHIFT); + } else { + addr = start; + } + return addr; +} + +unsigned long vdso_size(void) +{ + unsigned long size = VVAR_NR_PAGES * PAGE_SIZE; + + if (is_compat_task()) + size += vdso32_end - vdso32_start; + else + size += vdso64_end - vdso64_start; + return PAGE_ALIGN(size); +} + +int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) +{ + unsigned long addr = VDSO_BASE; + unsigned long size = vdso_size(); + + if (current->flags & PF_RANDOMIZE) + addr = vdso_addr(current->mm->start_stack + PAGE_SIZE, size); + return map_vdso(addr, size); +} + static struct page ** __init vdso_setup_pages(void *start, void *end) { int pages = (end - start) >> PAGE_SHIFT; |