From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932765Ab3CVNLa (ORCPT ); Fri, 22 Mar 2013 09:11:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47805 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932361Ab3CVNJf (ORCPT ); Fri, 22 Mar 2013 09:09:35 -0400 From: Anton Arapov To: Anton Arapov , Oleg Nesterov , Srikar Dronamraju Cc: LKML , Josh Stone , Frank Eigler , Peter Zijlstra , Ingo Molnar , Ananth N Mavinakayanahalli , adrian.m.negreanu@intel.com, Torsten.Polle@gmx.de Subject: [PATCH 3/7] uretprobes/x86: hijack return address Date: Fri, 22 Mar 2013 14:09:00 +0100 Message-Id: <1363957745-6657-4-git-send-email-anton@redhat.com> In-Reply-To: <1363957745-6657-1-git-send-email-anton@redhat.com> References: <1363957745-6657-1-git-send-email-anton@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org - Hijack the return address and replace it with a trampoline address. RFCv5 changes: - change the fail return code, because orig_ret_vaddr=0 is possible - style fixup RFCv2 changes: - remove ->doomed flag, kill task immediately Signed-off-by: Anton Arapov --- arch/x86/include/asm/uprobes.h | 1 + arch/x86/kernel/uprobes.c | 29 +++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index 8ff8be7..6e51979 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -55,4 +55,5 @@ extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs); extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk); extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data); extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs); +extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs); #endif /* _ASM_UPROBES_H */ diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 0ba4cfb..05d357e 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -697,3 +697,32 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) send_sig(SIGTRAP, current, 0); return ret; } + +unsigned long +arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs) +{ + int rasize, ncopied; + unsigned long orig_ret_vaddr = 0; /* clear high bits for 32-bit apps */ + + rasize = is_ia32_task() ? 4 : 8; + ncopied = copy_from_user(&orig_ret_vaddr, (void __user *)regs->sp, rasize); + if (unlikely(ncopied)) + return -1; + + /* check whether address has been already hijacked */ + if (orig_ret_vaddr == trampoline_vaddr) + return orig_ret_vaddr; + + ncopied = copy_to_user((void __user *)regs->sp, &trampoline_vaddr, rasize); + if (unlikely(ncopied)) { + if (ncopied != rasize) { + printk(KERN_ERR "uprobe: return address clobbered: " + "pid=%d, %%sp=%#lx, %%ip=%#lx\n", + current->pid, regs->sp, regs->ip); + /* kill task immediately */ + send_sig(SIGSEGV, current, 0); + } + } + + return orig_ret_vaddr; +} -- 1.8.1.4