Commit-ID: ed0b2edb61ba4e557de759093d965654186f28b2 Gitweb: http://git.kernel.org/tip/ed0b2edb61ba4e557de759093d965654186f28b2 Author: Brian Gerst <brge...@gmail.com> AuthorDate: Sun, 19 Jul 2015 21:09:06 -0400 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 21 Jul 2015 09:12:24 +0200
x86/entry/vm86: Move userspace accesses to do_sys_vm86() Move the userspace accesses down into the common function in preparation for the next set of patches. Also change to copying the fields explicitly instead of assuming a fixed order in pt_regs and the kernel data structures. Signed-off-by: Brian Gerst <brge...@gmail.com> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/1437354550-25858-4-git-send-email-brge...@gmail.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/include/asm/processor.h | 2 +- arch/x86/kernel/vm86_32.c | 189 +++++++++++++++++++++------------------ 2 files changed, 102 insertions(+), 89 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index f4e4e3f..35ad554 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -405,7 +405,7 @@ struct thread_struct { unsigned long error_code; #ifdef CONFIG_X86_32 /* Virtual 86 mode info */ - struct vm86_struct __user *vm86_info; + struct vm86plus_struct __user *vm86_info; unsigned long screen_bitmap; unsigned long v86flags; unsigned long v86mask; diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c index 9a2dc80..e6c2b47 100644 --- a/arch/x86/kernel/vm86_32.c +++ b/arch/x86/kernel/vm86_32.c @@ -90,46 +90,13 @@ #define SAFE_MASK (0xDD5) #define RETURN_MASK (0xDFF) -/* convert kernel_vm86_regs to vm86_regs */ -static int copy_vm86_regs_to_user(struct vm86_regs __user *user, - const struct kernel_vm86_regs *regs) -{ - int ret = 0; - - /* - * kernel_vm86_regs is missing gs, so copy everything up to - * (but not including) orig_eax, and then rest including orig_eax. - */ - ret += copy_to_user(user, regs, offsetof(struct kernel_vm86_regs, pt.orig_ax)); - ret += copy_to_user(&user->orig_eax, ®s->pt.orig_ax, - sizeof(struct kernel_vm86_regs) - - offsetof(struct kernel_vm86_regs, pt.orig_ax)); - - return ret; -} - -/* convert vm86_regs to kernel_vm86_regs */ -static int copy_vm86_regs_from_user(struct kernel_vm86_regs *regs, - const struct vm86_regs __user *user, - unsigned extra) -{ - int ret = 0; - - /* copy ax-fs inclusive */ - ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.orig_ax)); - /* copy orig_ax-__gsh+extra */ - ret += copy_from_user(®s->pt.orig_ax, &user->orig_eax, - sizeof(struct kernel_vm86_regs) - - offsetof(struct kernel_vm86_regs, pt.orig_ax) + - extra); - return ret; -} - struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs) { struct tss_struct *tss; struct pt_regs *ret; - unsigned long tmp; + struct task_struct *tsk = current; + struct vm86plus_struct __user *user; + long err = 0; /* * This gets called from entry.S with interrupts disabled, but @@ -138,23 +105,50 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs) */ local_irq_enable(); - if (!current->thread.vm86_info) { + if (!tsk->thread.vm86_info) { pr_alert("no vm86_info: BAD\n"); do_exit(SIGSEGV); } - set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | current->thread.v86mask); - tmp = copy_vm86_regs_to_user(¤t->thread.vm86_info->regs, regs); - tmp += put_user(current->thread.screen_bitmap, ¤t->thread.vm86_info->screen_bitmap); - if (tmp) { + set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | tsk->thread.v86mask); + user = tsk->thread.vm86_info; + + if (!access_ok(VERIFY_WRITE, user, VMPI.is_vm86pus ? + sizeof(struct vm86plus_struct) : + sizeof(struct vm86_struct))) { + pr_alert("could not access userspace vm86_info\n"); + do_exit(SIGSEGV); + } + + put_user_try { + put_user_ex(regs->pt.bx, &user->regs.ebx); + put_user_ex(regs->pt.cx, &user->regs.ecx); + put_user_ex(regs->pt.dx, &user->regs.edx); + put_user_ex(regs->pt.si, &user->regs.esi); + put_user_ex(regs->pt.di, &user->regs.edi); + put_user_ex(regs->pt.bp, &user->regs.ebp); + put_user_ex(regs->pt.ax, &user->regs.eax); + put_user_ex(regs->pt.ip, &user->regs.eip); + put_user_ex(regs->pt.cs, &user->regs.cs); + put_user_ex(regs->pt.flags, &user->regs.eflags); + put_user_ex(regs->pt.sp, &user->regs.esp); + put_user_ex(regs->pt.ss, &user->regs.ss); + put_user_ex(regs->es, &user->regs.es); + put_user_ex(regs->ds, &user->regs.ds); + put_user_ex(regs->fs, &user->regs.fs); + put_user_ex(regs->gs, &user->regs.gs); + + put_user_ex(tsk->thread.screen_bitmap, &user->screen_bitmap); + } put_user_catch(err); + if (err) { pr_alert("could not access userspace vm86_info\n"); do_exit(SIGSEGV); } tss = &per_cpu(cpu_tss, get_cpu()); - current->thread.sp0 = current->thread.saved_sp0; - current->thread.sysenter_cs = __KERNEL_CS; - load_sp0(tss, ¤t->thread); - current->thread.saved_sp0 = 0; + tsk->thread.sp0 = tsk->thread.saved_sp0; + tsk->thread.sysenter_cs = __KERNEL_CS; + load_sp0(tss, &tsk->thread); + tsk->thread.saved_sp0 = 0; put_cpu(); ret = KVM86->regs32; @@ -199,7 +193,8 @@ out: static int do_vm86_irq_handling(int subfunction, int irqnumber); -static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk); +static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus, + struct kernel_vm86_struct *info); SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86) { @@ -208,21 +203,8 @@ SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86) * This remains on the stack until we * return to 32 bit user space. */ - struct task_struct *tsk = current; - int tmp; - if (tsk->thread.saved_sp0) - return -EPERM; - tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs, - offsetof(struct kernel_vm86_struct, vm86plus) - - sizeof(info.regs)); - if (tmp) - return -EFAULT; - memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus); - info.regs32 = current_pt_regs(); - tsk->thread.vm86_info = v86; - do_sys_vm86(&info, tsk); - return 0; /* we never return here */ + return do_sys_vm86((struct vm86plus_struct __user *) v86, false, &info); } @@ -233,11 +215,7 @@ SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg) * This remains on the stack until we * return to 32 bit user space. */ - struct task_struct *tsk; - int tmp; - struct vm86plus_struct __user *v86; - tsk = current; switch (cmd) { case VM86_REQUEST_IRQ: case VM86_FREE_IRQ: @@ -255,34 +233,69 @@ SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg) } /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ - if (tsk->thread.saved_sp0) - return -EPERM; - v86 = (struct vm86plus_struct __user *)arg; - tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs, - offsetof(struct kernel_vm86_struct, regs32) - - sizeof(info.regs)); - if (tmp) - return -EFAULT; - info.regs32 = current_pt_regs(); - info.vm86plus.is_vm86pus = 1; - tsk->thread.vm86_info = (struct vm86_struct __user *)v86; - do_sys_vm86(&info, tsk); - return 0; /* we never return here */ + return do_sys_vm86((struct vm86plus_struct __user *) arg, true, &info); } -static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk) +static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus, + struct kernel_vm86_struct *info) { struct tss_struct *tss; -/* - * make sure the vm86() system call doesn't try to do anything silly - */ - info->regs.pt.ds = 0; - info->regs.pt.es = 0; - info->regs.pt.fs = 0; -#ifndef CONFIG_X86_32_LAZY_GS - info->regs.pt.gs = 0; -#endif + struct task_struct *tsk = current; + unsigned long err = 0; + + if (tsk->thread.saved_sp0) + return -EPERM; + + if (!access_ok(VERIFY_READ, v86, plus ? + sizeof(struct vm86_struct) : + sizeof(struct vm86plus_struct))) + return -EFAULT; + + memset(info, 0, sizeof(*info)); + get_user_try { + unsigned short seg; + get_user_ex(info->regs.pt.bx, &v86->regs.ebx); + get_user_ex(info->regs.pt.cx, &v86->regs.ecx); + get_user_ex(info->regs.pt.dx, &v86->regs.edx); + get_user_ex(info->regs.pt.si, &v86->regs.esi); + get_user_ex(info->regs.pt.di, &v86->regs.edi); + get_user_ex(info->regs.pt.bp, &v86->regs.ebp); + get_user_ex(info->regs.pt.ax, &v86->regs.eax); + get_user_ex(info->regs.pt.ip, &v86->regs.eip); + get_user_ex(seg, &v86->regs.cs); + info->regs.pt.cs = seg; + get_user_ex(info->regs.pt.flags, &v86->regs.eflags); + get_user_ex(info->regs.pt.sp, &v86->regs.esp); + get_user_ex(seg, &v86->regs.ss); + info->regs.pt.ss = seg; + get_user_ex(info->regs.es, &v86->regs.es); + get_user_ex(info->regs.ds, &v86->regs.ds); + get_user_ex(info->regs.fs, &v86->regs.fs); + get_user_ex(info->regs.gs, &v86->regs.gs); + + get_user_ex(info->flags, &v86->flags); + get_user_ex(info->screen_bitmap, &v86->screen_bitmap); + get_user_ex(info->cpu_type, &v86->cpu_type); + } get_user_catch(err); + if (err) + return err; + + if (copy_from_user(&info->int_revectored, &v86->int_revectored, + sizeof(struct revectored_struct))) + return -EFAULT; + if (copy_from_user(&info->int21_revectored, &v86->int21_revectored, + sizeof(struct revectored_struct))) + return -EFAULT; + if (plus) { + if (copy_from_user(&info->vm86plus, &v86->vm86plus, + sizeof(struct vm86plus_info_struct))) + return -EFAULT; + info->vm86plus.is_vm86pus = 1; + } + + info->regs32 = current_pt_regs(); + tsk->thread.vm86_info = v86; /* * The flags register is also special: we cannot trust that the user @@ -344,7 +357,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk "jmp resume_userspace" : /* no outputs */ :"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0)); - /* we never return here */ + unreachable(); /* we never return here */ } static inline void return_to_32bit(struct kernel_vm86_regs *regs16, int retval) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
