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-rw-r--r--arch/x86/entry/vdso/vma.c460
1 files changed, 460 insertions, 0 deletions
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
new file mode 100644
index 000000000..2b5e04cc4
--- /dev/null
+++ b/arch/x86/entry/vdso/vma.c
@@ -0,0 +1,460 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2007 Andi Kleen, SUSE Labs.
+ *
+ * This contains most of the x86 vDSO kernel-side code.
+ */
+#include <linux/mm.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/random.h>
+#include <linux/elf.h>
+#include <linux/cpu.h>
+#include <linux/ptrace.h>
+#include <linux/time_namespace.h>
+
+#include <asm/pvclock.h>
+#include <asm/vgtod.h>
+#include <asm/proto.h>
+#include <asm/vdso.h>
+#include <asm/vvar.h>
+#include <asm/tlb.h>
+#include <asm/page.h>
+#include <asm/desc.h>
+#include <asm/cpufeature.h>
+#include <clocksource/hyperv_timer.h>
+
+#undef _ASM_X86_VVAR_H
+#define EMIT_VVAR(name, offset) \
+ const size_t name ## _offset = offset;
+#include <asm/vvar.h>
+
+struct vdso_data *arch_get_vdso_data(void *vvar_page)
+{
+ return (struct vdso_data *)(vvar_page + _vdso_data_offset);
+}
+#undef EMIT_VVAR
+
+unsigned int vclocks_used __read_mostly;
+
+#if defined(CONFIG_X86_64)
+unsigned int __read_mostly vdso64_enabled = 1;
+#endif
+
+void __init init_vdso_image(const struct vdso_image *image)
+{
+ BUG_ON(image->size % PAGE_SIZE != 0);
+
+ apply_alternatives((struct alt_instr *)(image->data + image->alt),
+ (struct alt_instr *)(image->data + image->alt +
+ image->alt_len));
+}
+
+static const struct vm_special_mapping vvar_mapping;
+struct linux_binprm;
+
+static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
+ struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ const struct vdso_image *image = vma->vm_mm->context.vdso_image;
+
+ if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size)
+ return VM_FAULT_SIGBUS;
+
+ vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT));
+ get_page(vmf->page);
+ return 0;
+}
+
+static void vdso_fix_landing(const struct vdso_image *image,
+ struct vm_area_struct *new_vma)
+{
+#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+ if (in_ia32_syscall() && image == &vdso_image_32) {
+ struct pt_regs *regs = current_pt_regs();
+ unsigned long vdso_land = image->sym_int80_landing_pad;
+ unsigned long old_land_addr = vdso_land +
+ (unsigned long)current->mm->context.vdso;
+
+ /* Fixing userspace landing - look at do_fast_syscall_32 */
+ if (regs->ip == old_land_addr)
+ regs->ip = new_vma->vm_start + vdso_land;
+ }
+#endif
+}
+
+static int vdso_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;
+ const struct vdso_image *image = current->mm->context.vdso_image;
+
+ if (image->size != new_size)
+ return -EINVAL;
+
+ vdso_fix_landing(image, new_vma);
+ current->mm->context.vdso = (void __user *)new_vma->vm_start;
+
+ return 0;
+}
+
+static int vvar_mremap(const struct vm_special_mapping *sm,
+ struct vm_area_struct *new_vma)
+{
+ const struct vdso_image *image = new_vma->vm_mm->context.vdso_image;
+ unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+
+ if (new_size != -image->sym_vvar_start)
+ return -EINVAL;
+
+ return 0;
+}
+
+#ifdef CONFIG_TIME_NS
+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;
+}
+
+/*
+ * The vvar page layout depends on whether a task belongs to the root or
+ * non-root time namespace. Whenever a task changes its namespace, the VVAR
+ * page tables are cleared and then they will re-faulted with a
+ * corresponding layout.
+ * See also the comment near timens_setup_vdso_data() for details.
+ */
+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;
+
+ if (vma_is_special_mapping(vma, &vvar_mapping))
+ zap_page_range(vma, vma->vm_start, size);
+ }
+
+ mmap_read_unlock(mm);
+ return 0;
+}
+#else
+static inline 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)
+{
+ const struct vdso_image *image = vma->vm_mm->context.vdso_image;
+ unsigned long pfn;
+ long sym_offset;
+
+ if (!image)
+ return VM_FAULT_SIGBUS;
+
+ sym_offset = (long)(vmf->pgoff << PAGE_SHIFT) +
+ image->sym_vvar_start;
+
+ /*
+ * Sanity check: a symbol offset of zero means that the page
+ * does not exist for this vdso image, not that the page is at
+ * offset zero relative to the text mapping. This should be
+ * impossible here, because sym_offset should only be zero for
+ * the page past the end of the vvar mapping.
+ */
+ if (sym_offset == 0)
+ return VM_FAULT_SIGBUS;
+
+ if (sym_offset == image->sym_vvar_page) {
+ struct page *timens_page = find_timens_vvar_page(vma);
+
+ pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
+
+ /*
+ * If a task belongs to a time namespace then a namespace
+ * specific VVAR is mapped with the sym_vvar_page offset and
+ * the real VVAR page is mapped with the sym_timens_page
+ * offset.
+ * See also the comment near timens_setup_vdso_data().
+ */
+ if (timens_page) {
+ unsigned long addr;
+ vm_fault_t err;
+
+ /*
+ * Optimization: inside time namespace pre-fault
+ * VVAR page too. As on timens page there are only
+ * offsets for clocks on VVAR, it'll be faulted
+ * shortly by VDSO code.
+ */
+ addr = vmf->address + (image->sym_timens_page - sym_offset);
+ err = vmf_insert_pfn(vma, addr, pfn);
+ if (unlikely(err & VM_FAULT_ERROR))
+ return err;
+
+ pfn = page_to_pfn(timens_page);
+ }
+
+ return vmf_insert_pfn(vma, vmf->address, pfn);
+ } else if (sym_offset == image->sym_pvclock_page) {
+ struct pvclock_vsyscall_time_info *pvti =
+ pvclock_get_pvti_cpu0_va();
+ if (pvti && vclock_was_used(VDSO_CLOCKMODE_PVCLOCK)) {
+ return vmf_insert_pfn_prot(vma, vmf->address,
+ __pa(pvti) >> PAGE_SHIFT,
+ pgprot_decrypted(vma->vm_page_prot));
+ }
+ } else if (sym_offset == image->sym_hvclock_page) {
+ struct ms_hyperv_tsc_page *tsc_pg = hv_get_tsc_page();
+
+ if (tsc_pg && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
+ return vmf_insert_pfn(vma, vmf->address,
+ virt_to_phys(tsc_pg) >> PAGE_SHIFT);
+ } else if (sym_offset == image->sym_timens_page) {
+ struct page *timens_page = find_timens_vvar_page(vma);
+
+ if (!timens_page)
+ return VM_FAULT_SIGBUS;
+
+ pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
+ return vmf_insert_pfn(vma, vmf->address, pfn);
+ }
+
+ return VM_FAULT_SIGBUS;
+}
+
+static const struct vm_special_mapping vdso_mapping = {
+ .name = "[vdso]",
+ .fault = vdso_fault,
+ .mremap = vdso_mremap,
+};
+static const struct vm_special_mapping vvar_mapping = {
+ .name = "[vvar]",
+ .fault = vvar_fault,
+ .mremap = vvar_mremap,
+};
+
+/*
+ * Add vdso and vvar mappings to current process.
+ * @image - blob to map
+ * @addr - request a specific address (zero to map at free addr)
+ */
+static int map_vdso(const struct vdso_image *image, unsigned long addr)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ unsigned long text_start;
+ int ret = 0;
+
+ if (mmap_write_lock_killable(mm))
+ return -EINTR;
+
+ addr = get_unmapped_area(NULL, addr,
+ image->size - image->sym_vvar_start, 0, 0);
+ if (IS_ERR_VALUE(addr)) {
+ ret = addr;
+ goto up_fail;
+ }
+
+ text_start = addr - image->sym_vvar_start;
+
+ /*
+ * MAYWRITE to allow gdb to COW and set breakpoints
+ */
+ vma = _install_special_mapping(mm,
+ text_start,
+ image->size,
+ VM_READ|VM_EXEC|
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+ &vdso_mapping);
+
+ if (IS_ERR(vma)) {
+ ret = PTR_ERR(vma);
+ goto up_fail;
+ }
+
+ vma = _install_special_mapping(mm,
+ addr,
+ -image->sym_vvar_start,
+ VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
+ VM_PFNMAP,
+ &vvar_mapping);
+
+ if (IS_ERR(vma)) {
+ ret = PTR_ERR(vma);
+ do_munmap(mm, text_start, image->size, NULL);
+ } else {
+ current->mm->context.vdso = (void __user *)text_start;
+ current->mm->context.vdso_image = image;
+ }
+
+up_fail:
+ mmap_write_unlock(mm);
+ return ret;
+}
+
+#ifdef CONFIG_X86_64
+/*
+ * Put the vdso above the (randomized) stack with another randomized
+ * offset. This way there is no hole in the middle of address space.
+ * To save memory make sure it is still in the same PTE as the stack
+ * top. This doesn't give that many random bits.
+ *
+ * Note that this algorithm is imperfect: the distribution of the vdso
+ * start address within a PMD is biased toward the end.
+ *
+ * Only used for the 64-bit and x32 vdsos.
+ */
+static unsigned long vdso_addr(unsigned long start, unsigned len)
+{
+ unsigned long addr, end;
+ unsigned 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 >= DEFAULT_MAP_WINDOW)
+ end = DEFAULT_MAP_WINDOW;
+ end -= len;
+
+ if (end > start) {
+ offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
+ addr = start + (offset << PAGE_SHIFT);
+ } else {
+ addr = start;
+ }
+
+ /*
+ * Forcibly align the final address in case we have a hardware
+ * issue that requires alignment for performance reasons.
+ */
+ addr = align_vdso_addr(addr);
+
+ return addr;
+}
+
+static int map_vdso_randomized(const struct vdso_image *image)
+{
+ unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start);
+
+ return map_vdso(image, addr);
+}
+#endif
+
+int map_vdso_once(const struct vdso_image *image, unsigned long addr)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+
+ mmap_write_lock(mm);
+ /*
+ * Check if we have already mapped vdso blob - fail to prevent
+ * abusing from userspace install_speciall_mapping, which may
+ * not do accounting and rlimit right.
+ * We could search vma near context.vdso, but it's a slowpath,
+ * so let's explicitly check all VMAs to be completely sure.
+ */
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (vma_is_special_mapping(vma, &vdso_mapping) ||
+ vma_is_special_mapping(vma, &vvar_mapping)) {
+ mmap_write_unlock(mm);
+ return -EEXIST;
+ }
+ }
+ mmap_write_unlock(mm);
+
+ return map_vdso(image, addr);
+}
+
+#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
+static int load_vdso32(void)
+{
+ if (vdso32_enabled != 1) /* Other values all mean "disabled" */
+ return 0;
+
+ return map_vdso(&vdso_image_32, 0);
+}
+#endif
+
+#ifdef CONFIG_X86_64
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+ if (!vdso64_enabled)
+ return 0;
+
+ return map_vdso_randomized(&vdso_image_64);
+}
+
+#ifdef CONFIG_COMPAT
+int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
+ int uses_interp)
+{
+#ifdef CONFIG_X86_X32_ABI
+ if (test_thread_flag(TIF_X32)) {
+ if (!vdso64_enabled)
+ return 0;
+ return map_vdso_randomized(&vdso_image_x32);
+ }
+#endif
+#ifdef CONFIG_IA32_EMULATION
+ return load_vdso32();
+#else
+ return 0;
+#endif
+}
+#endif
+#else
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+ return load_vdso32();
+}
+#endif
+
+#ifdef CONFIG_X86_64
+static __init int vdso_setup(char *s)
+{
+ vdso64_enabled = simple_strtoul(s, NULL, 0);
+ return 1;
+}
+__setup("vdso=", vdso_setup);
+
+static int __init init_vdso(void)
+{
+ BUILD_BUG_ON(VDSO_CLOCKMODE_MAX >= 32);
+
+ init_vdso_image(&vdso_image_64);
+
+#ifdef CONFIG_X86_X32_ABI
+ init_vdso_image(&vdso_image_x32);
+#endif
+
+ return 0;
+}
+subsys_initcall(init_vdso);
+#endif /* CONFIG_X86_64 */
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