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 <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Cyrill Gorcunov <[email protected]> Cc: Pavel Emelyanov <[email protected]> Signed-off-by: Dmitry Safonov <[email protected]> --- 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 ++++++++++++++++++++++ 4 files changed, 68 insertions(+), 10 deletions(-) diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 5bcb25a9e573..dad2b2d8ff03 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->vm_private_data == &vdso_mapping || + vma->vm_private_data == &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; -- 2.9.0
