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[209.132.180.67]) by mx.google.com with ESMTP id r24-v6si9620889pgv.380.2018.10.15.04.23.38; Mon, 15 Oct 2018 04:23:53 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=i1ky1Gvr; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726669AbeJOTHE (ORCPT + 99 others); Mon, 15 Oct 2018 15:07:04 -0400 Received: from mail-io1-f67.google.com ([209.85.166.67]:35741 "EHLO mail-io1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726639AbeJOTHD (ORCPT ); Mon, 15 Oct 2018 15:07:03 -0400 Received: by mail-io1-f67.google.com with SMTP id w11-v6so13952723iob.2 for ; Mon, 15 Oct 2018 04:22:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=dbAK2nN07D4ZfcKAxWHght6LvVbwH9bGhkb//otxtHg=; b=i1ky1GvremtWB3x6EvpTmQSLrH0gFItZBUScWc9U8RTJEnLkpQ+lmebhzQKpMN/IXf dYd3BUJ3XQ/qtOTUHTz81qX3a8F9rNAMWscf8X6MjBs0z1mdAIIFVTPiGdc1VEVbn2In IoWQV/fIonWiqj/fcIfGPGvOBxjgStltalm0g= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=dbAK2nN07D4ZfcKAxWHght6LvVbwH9bGhkb//otxtHg=; b=ujOlshYFHmRYEzLBya5YNMNDzxqzX9TfG4qMeQVmHwuCCnDEbBPsymt8z4FRoiQnz9 rZxvsys3RJhuj47VD0m6mZHQ+u9g1z3z/Z/xz/6bXU99Rya9LFIYnSNKj6t/mHVDARzg hJfwT+iRCUQ0uUf9sph1IyKSjGAgRdeXxXrr5hEKq9Xk9Oc8rb3H1nYnKyr+VfYG9qLk fp299SHugeQItbT1uDhRhqp/oAp8HNQXJzy3BT/+8bXgJg6TSv0kzgLnCuhVEV8nFSvD A62b9E+8tUNb26/UeTTiU7IVzYIBiX2YuUrTprFsaNhG1RNxC+Kji7uL9ldz6HY96KYw wyeQ== X-Gm-Message-State: ABuFfojCofEyXX2+8qQhyaMuZqAQuq6eX0YcPbWEYn5OCZBVemEkalJc nhZ+CbFPbnqrlRLSyRo/mP/iFe/i1taVF0QLWZohnQ== X-Received: by 2002:a6b:be83:: with SMTP id o125-v6mr11269994iof.173.1539602533408; Mon, 15 Oct 2018 04:22:13 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a6b:5910:0:0:0:0:0 with HTTP; Mon, 15 Oct 2018 04:22:12 -0700 (PDT) In-Reply-To: <20181015111600.5479-1-anders.roxell@linaro.org> References: <20181015111600.5479-1-anders.roxell@linaro.org> From: Ard Biesheuvel Date: Mon, 15 Oct 2018 13:22:12 +0200 Message-ID: Subject: Re: [PATCH] arm64: kprobe: make page to RO mode when allocate it To: Anders Roxell , Masami Hiramatsu Cc: Catalin Marinas , Will Deacon , linux-arm-kernel , Linux Kernel Mailing List , Arnd Bergmann , Laura Abbott Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (+ Masami) On 15 October 2018 at 13:16, Anders Roxell wrote: > Commit 1404d6f13e47 ("arm64: dump: Add checking for writable and exectuable pages") > has successfully identified code that leaves a page with W+X > permissions. > > [ 3.245140] arm64/mm: Found insecure W+X mapping at address (____ptrval____)/0xffff000000d90000 > [ 3.245771] WARNING: CPU: 0 PID: 1 at ../arch/arm64/mm/dump.c:232 note_page+0x410/0x420 > [ 3.246141] Modules linked in: > [ 3.246653] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc5-next-20180928-00001-ge70ae259b853-dirty #62 > [ 3.247008] Hardware name: linux,dummy-virt (DT) > [ 3.247347] pstate: 80000005 (Nzcv daif -PAN -UAO) > [ 3.247623] pc : note_page+0x410/0x420 > [ 3.247898] lr : note_page+0x410/0x420 > [ 3.248071] sp : ffff00000804bcd0 > [ 3.248254] x29: ffff00000804bcd0 x28: ffff000009274000 > [ 3.248578] x27: ffff00000921a000 x26: ffff80007dfff000 > [ 3.248845] x25: ffff0000093f5000 x24: ffff000009526f6a > [ 3.249109] x23: 0000000000000004 x22: ffff000000d91000 > [ 3.249396] x21: ffff000000d90000 x20: 0000000000000000 > [ 3.249661] x19: ffff00000804bde8 x18: 0000000000000400 > [ 3.249924] x17: 0000000000000000 x16: 0000000000000000 > [ 3.250271] x15: ffffffffffffffff x14: 295f5f5f5f6c6176 > [ 3.250594] x13: 7274705f5f5f5f28 x12: 2073736572646461 > [ 3.250941] x11: 20746120676e6970 x10: 70616d20582b5720 > [ 3.251252] x9 : 6572756365736e69 x8 : 3039643030303030 > [ 3.251519] x7 : 306666666678302f x6 : ffff0000095467b2 > [ 3.251802] x5 : 0000000000000000 x4 : 0000000000000000 > [ 3.252060] x3 : 0000000000000000 x2 : ffffffffffffffff > [ 3.252323] x1 : 4d151327adc50b00 x0 : 0000000000000000 > [ 3.252664] Call trace: > [ 3.252953] note_page+0x410/0x420 > [ 3.253186] walk_pgd+0x12c/0x238 > [ 3.253417] ptdump_check_wx+0x68/0xf8 > [ 3.253637] mark_rodata_ro+0x68/0x98 > [ 3.253847] kernel_init+0x38/0x160 > [ 3.254103] ret_from_fork+0x10/0x18 > > Reworked to that when allocate a page it sets mode RO. Inspired by > commit 63fef14fc98a ("kprobes/x86: Make insn buffer always ROX and use text_poke()"). > > Cc: Arnd Bergmann > Cc: Ard Biesheuvel > Cc: Laura Abbott > Cc: Catalin Marinas > Co-developed-by: Arnd Bergmann > Co-developed-by: Ard Biesheuvel > Signed-off-by: Anders Roxell > --- > arch/arm64/kernel/probes/kprobes.c | 27 ++++++++++++++++++++------- > 1 file changed, 20 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c > index 9b65132e789a..b842e908b423 100644 > --- a/arch/arm64/kernel/probes/kprobes.c > +++ b/arch/arm64/kernel/probes/kprobes.c > @@ -23,7 +23,9 @@ > #include > #include > #include > +#include > #include > +#include > #include > #include > #include > @@ -42,10 +44,21 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); > static void __kprobes > post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); > > +static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode) > +{ > + void *addrs[1]; > + u32 insns[1]; > + > + addrs[0] = (void *)addr; > + insns[0] = (u32)opcode; > + > + return aarch64_insn_patch_text(addrs, insns, 1); > +} > + > static void __kprobes arch_prepare_ss_slot(struct kprobe *p) > { > /* prepare insn slot */ > - p->ainsn.api.insn[0] = cpu_to_le32(p->opcode); > + patch_text(p->ainsn.api.insn, p->opcode); > > flush_icache_range((uintptr_t) (p->ainsn.api.insn), > (uintptr_t) (p->ainsn.api.insn) + > @@ -118,15 +131,15 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) > return 0; > } > > -static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode) > +void *alloc_insn_page(void) > { > - void *addrs[1]; > - u32 insns[1]; > + void *page; > > - addrs[0] = (void *)addr; > - insns[0] = (u32)opcode; > + page = vmalloc_exec(PAGE_SIZE); > + if (page) > + set_memory_ro((unsigned long)page & PAGE_MASK, 1); > > - return aarch64_insn_patch_text(addrs, insns, 1); > + return page; > } > > /* arm kprobe: install breakpoint in text */ > -- > 2.19.1 >