[PATCHv5 3/6] x86/arch_prctl/vdso: add ARCH_MAP_VDSO_*
From: Dmitry Safonov
Date: Mon Sep 05 2016 - 09:35:42 EST
Add API to change vdso blob type with arch_prctl.
As this is usefull only by needs of CRIU, expose
this interface under CONFIG_CHECKPOINT_RESTORE.
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: x86@xxxxxxxxxx
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Dmitry Safonov <dsafonov@xxxxxxxxxxxxx>
---
arch/x86/entry/vdso/vma.c | 45 ++++++++++++++++++++++++++++++---------
arch/x86/include/asm/vdso.h | 2 ++
arch/x86/include/uapi/asm/prctl.h | 6 ++++++
arch/x86/kernel/process_64.c | 25 ++++++++++++++++++++++
include/linux/mm.h | 2 ++
mm/mmap.c | 8 +++++++
6 files changed, 78 insertions(+), 10 deletions(-)
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 5bcb25a9e573..4459e73e234d 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -176,6 +176,16 @@ static int vvar_fault(const struct vm_special_mapping *sm,
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,
+};
+
/*
* Add vdso and vvar mappings to current process.
* @image - blob to map
@@ -188,16 +198,6 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr)
unsigned long text_start;
int ret = 0;
- 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,
- };
-
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
@@ -256,6 +256,31 @@ static int map_vdso_randomized(const struct vdso_image *image)
return map_vdso(image, addr);
}
+int map_vdso_once(const struct vdso_image *image, unsigned long addr)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+
+ down_write(&mm->mmap_sem);
+ /*
+ * 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 explicitely 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)) {
+ up_write(&mm->mmap_sem);
+ return -EEXIST;
+ }
+ }
+ up_write(&mm->mmap_sem);
+
+ return map_vdso(image, addr);
+}
+
#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
static int load_vdso32(void)
{
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 43dc55be524e..2444189cbe28 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -41,6 +41,8 @@ extern const struct vdso_image vdso_image_32;
extern void __init init_vdso_image(const struct vdso_image *image);
+extern int map_vdso_once(const struct vdso_image *image, unsigned long addr);
+
#endif /* __ASSEMBLER__ */
#endif /* _ASM_X86_VDSO_H */
diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h
index 3ac5032fae09..ae135de547f5 100644
--- a/arch/x86/include/uapi/asm/prctl.h
+++ b/arch/x86/include/uapi/asm/prctl.h
@@ -6,4 +6,10 @@
#define ARCH_GET_FS 0x1003
#define ARCH_GET_GS 0x1004
+#ifdef CONFIG_CHECKPOINT_RESTORE
+# define ARCH_MAP_VDSO_X32 0x2001
+# define ARCH_MAP_VDSO_32 0x2002
+# define ARCH_MAP_VDSO_64 0x2003
+#endif
+
#endif /* _ASM_X86_PRCTL_H */
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 63236d8f84bf..f240a465920b 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -49,6 +49,7 @@
#include <asm/debugreg.h>
#include <asm/switch_to.h>
#include <asm/xen/hypervisor.h>
+#include <asm/vdso.h>
asmlinkage extern void ret_from_fork(void);
@@ -524,6 +525,17 @@ void set_personality_ia32(bool x32)
}
EXPORT_SYMBOL_GPL(set_personality_ia32);
+static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr)
+{
+ int ret;
+
+ ret = map_vdso_once(image, addr);
+ if (ret)
+ return ret;
+
+ return (long)image->size;
+}
+
long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
{
int ret = 0;
@@ -577,6 +589,19 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
break;
}
+#ifdef CONFIG_CHECKPOINT_RESTORE
+#ifdef CONFIG_X86_X32
+ case ARCH_MAP_VDSO_X32:
+ return prctl_map_vdso(&vdso_image_x32, addr);
+#endif
+#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+ case ARCH_MAP_VDSO_32:
+ return prctl_map_vdso(&vdso_image_32, addr);
+#endif
+ case ARCH_MAP_VDSO_64:
+ return prctl_map_vdso(&vdso_image_64, addr);
+#endif
+
default:
ret = -EINVAL;
break;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ef815b9cd426..5f14534f0c90 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2019,6 +2019,8 @@ extern struct file *get_task_exe_file(struct task_struct *task);
extern bool may_expand_vm(struct mm_struct *, vm_flags_t, unsigned long npages);
extern void vm_stat_account(struct mm_struct *, vm_flags_t, long npages);
+extern bool vma_is_special_mapping(const struct vm_area_struct *vma,
+ const struct vm_special_mapping *sm);
extern struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
unsigned long addr, unsigned long len,
unsigned long flags,
diff --git a/mm/mmap.c b/mm/mmap.c
index ca9d91bca0d6..6373ebd358c0 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3063,6 +3063,14 @@ out:
return ERR_PTR(ret);
}
+bool vma_is_special_mapping(const struct vm_area_struct *vma,
+ const struct vm_special_mapping *sm)
+{
+ return vma->vm_private_data == sm &&
+ (vma->vm_ops == &special_mapping_vmops ||
+ vma->vm_ops == &legacy_special_mapping_vmops);
+}
+
/*
* Called with mm->mmap_sem held for writing.
* Insert a new vma covering the given region, with the given flags.
--
2.9.0