x86/vdso: Handle faults on timens page (af34ebeb) · Commits · 戴 / test

arch/x86/entry/vdso/vma.c

+52 −2

Original line number	Diff line number	Diff line
		@@ -14,11 +14,14 @@
		#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>
		@@ -107,10 +110,36 @@ static int vvar_mremap(const struct vm_special_mapping *sm,
		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;
		}
		#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)
		@@ -130,8 +159,21 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
		return VM_FAULT_SIGBUS;

		if (sym_offset == image->sym_vvar_page) {
		return vmf_insert_pfn(vma, vmf->address,
		__pa_symbol(&__vvar_page) >> PAGE_SHIFT);
		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)
		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();
		@@ -146,6 +188,14 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
		if (tsc_pg && vclock_was_used(VCLOCK_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;

mm/mmap.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -3342,6 +3342,8 @@ static const struct vm_operations_struct special_mapping_vmops = {
		.fault = special_mapping_fault,
		.mremap = special_mapping_mremap,
		.name = special_mapping_name,
		/* vDSO code relies that VVAR can't be accessed remotely */
		.access = NULL,
		};

		static const struct vm_operations_struct legacy_special_mapping_vmops = {

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