From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35E19C43331 for ; Fri, 27 Mar 2020 02:32:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C5642082D for ; Fri, 27 Mar 2020 02:32:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727962AbgC0Ccf (ORCPT ); Thu, 26 Mar 2020 22:32:35 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:48042 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727854AbgC0CcL (ORCPT ); Thu, 26 Mar 2020 22:32:11 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jHen1-003hSH-3o; Fri, 27 Mar 2020 02:32:07 +0000 From: Al Viro To: Linus Torvalds Cc: Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org Subject: [RFC][PATCH v2 16/22] x86: get rid of put_user_try in __setup_rt_frame() (both 32bit and 64bit) Date: Fri, 27 Mar 2020 02:31:59 +0000 Message-Id: <20200327023205.881896-16-viro@ZenIV.linux.org.uk> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200327023205.881896-1-viro@ZenIV.linux.org.uk> References: <20200327023007.GS23230@ZenIV.linux.org.uk> <20200327023205.881896-1-viro@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Al Viro Straightforward, except for save_altstack_ex() stuck in those. Replace that thing with an analogue that would use unsafe_put_user() instead of put_user_ex() (called compat_save_altstack()) and be done with that. Signed-off-by: Al Viro --- arch/x86/kernel/signal.c | 91 +++++++++++++++++++++++++----------------------- include/linux/signal.h | 8 ++--- 2 files changed, 52 insertions(+), 47 deletions(-) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 29abad29aaa1..8b879fdc214c 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -365,38 +365,37 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); - if (!access_ok(frame, sizeof(*frame))) + if (!user_access_begin(frame, sizeof(*frame))) return -EFAULT; - put_user_try { - put_user_ex(sig, &frame->sig); - put_user_ex(&frame->info, &frame->pinfo); - put_user_ex(&frame->uc, &frame->puc); + unsafe_put_user(sig, &frame->sig, Efault); + unsafe_put_user(&frame->info, &frame->pinfo, Efault); + unsafe_put_user(&frame->uc, &frame->puc, Efault); - /* Create the ucontext. */ - if (static_cpu_has(X86_FEATURE_XSAVE)) - put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); - else - put_user_ex(0, &frame->uc.uc_flags); - put_user_ex(0, &frame->uc.uc_link); - save_altstack_ex(&frame->uc.uc_stack, regs->sp); + /* Create the ucontext. */ + if (static_cpu_has(X86_FEATURE_XSAVE)) + unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault); + else + unsafe_put_user(0, &frame->uc.uc_flags, Efault); + unsafe_put_user(0, &frame->uc.uc_link, Efault); + unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); - /* Set up to return from userspace. */ - restorer = current->mm->context.vdso + - vdso_image_32.sym___kernel_rt_sigreturn; - if (ksig->ka.sa.sa_flags & SA_RESTORER) - restorer = ksig->ka.sa.sa_restorer; - put_user_ex(restorer, &frame->pretcode); + /* Set up to return from userspace. */ + restorer = current->mm->context.vdso + + vdso_image_32.sym___kernel_rt_sigreturn; + if (ksig->ka.sa.sa_flags & SA_RESTORER) + restorer = ksig->ka.sa.sa_restorer; + unsafe_put_user(restorer, &frame->pretcode, Efault); - /* - * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 - * - * WE DO NOT USE IT ANY MORE! It's only left here for historical - * reasons and because gdb uses it as a signature to notice - * signal handler stack frames. - */ - put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode); - } put_user_catch(err); + /* + * This is movl $__NR_rt_sigreturn, %ax ; int $0x80 + * + * WE DO NOT USE IT ANY MORE! It's only left here for historical + * reasons and because gdb uses it as a signature to notice + * signal handler stack frames. + */ + unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault); + user_access_end(); err |= copy_siginfo_to_user(&frame->info, &ksig->info); err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, @@ -419,6 +418,9 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, regs->cs = __USER_CS; return 0; +Efault: + user_access_end(); + return -EFAULT; } #else /* !CONFIG_X86_32 */ static unsigned long frame_uc_flags(struct pt_regs *regs) @@ -444,6 +446,10 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, unsigned long uc_flags; int err = 0; + /* x86-64 should always use SA_RESTORER. */ + if (!(ksig->ka.sa.sa_flags & SA_RESTORER)) + return -EFAULT; + frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); if (!access_ok(frame, sizeof(*frame))) @@ -455,23 +461,18 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, } uc_flags = frame_uc_flags(regs); + if (!user_access_begin(frame, sizeof(*frame))) + return -EFAULT; - put_user_try { - /* Create the ucontext. */ - put_user_ex(uc_flags, &frame->uc.uc_flags); - put_user_ex(0, &frame->uc.uc_link); - save_altstack_ex(&frame->uc.uc_stack, regs->sp); - - /* Set up to return from userspace. If provided, use a stub - already in userspace. */ - /* x86-64 should always use SA_RESTORER. */ - if (ksig->ka.sa.sa_flags & SA_RESTORER) { - put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode); - } else { - /* could use a vstub here */ - err |= -EFAULT; - } - } put_user_catch(err); + /* Create the ucontext. */ + unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault); + unsafe_put_user(0, &frame->uc.uc_link, Efault); + unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault); + + /* Set up to return from userspace. If provided, use a stub + already in userspace. */ + unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault); + user_access_end(); err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]); err |= __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]); @@ -515,6 +516,10 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, force_valid_ss(regs); return 0; + +Efault: + user_access_end(); + return -EFAULT; } #endif /* CONFIG_X86_32 */ diff --git a/include/linux/signal.h b/include/linux/signal.h index 1a5f88316b08..05bacd2ab135 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -444,12 +444,12 @@ void signals_init(void); int restore_altstack(const stack_t __user *); int __save_altstack(stack_t __user *, unsigned long); -#define save_altstack_ex(uss, sp) do { \ +#define unsafe_save_altstack(uss, sp, label) do { \ stack_t __user *__uss = uss; \ struct task_struct *t = current; \ - put_user_ex((void __user *)t->sas_ss_sp, &__uss->ss_sp); \ - put_user_ex(t->sas_ss_flags, &__uss->ss_flags); \ - put_user_ex(t->sas_ss_size, &__uss->ss_size); \ + unsafe_put_user((void __user *)t->sas_ss_sp, &__uss->ss_sp, label); \ + unsafe_put_user(t->sas_ss_flags, &__uss->ss_flags, label); \ + unsafe_put_user(t->sas_ss_size, &__uss->ss_size, label); \ if (t->sas_ss_flags & SS_AUTODISARM) \ sas_ss_reset(t); \ } while (0); -- 2.11.0