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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,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 60C12C10F0E for ; Mon, 8 Apr 2019 03:07:43 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7BE6020880 for ; Mon, 8 Apr 2019 03:07:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7BE6020880 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=informatik.wtf Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44cwMb42PPzDqK6 for ; Mon, 8 Apr 2019 13:07:39 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44cwKc0vMHzDq9Z for ; Mon, 8 Apr 2019 13:05:56 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=informatik.wtf Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) by bilbo.ozlabs.org (Postfix) with ESMTP id 44cwKZ4zd9z8tDC for ; Mon, 8 Apr 2019 13:05:54 +1000 (AEST) Received: by ozlabs.org (Postfix) id 44cwKZ4316z9sR3; Mon, 8 Apr 2019 13:05:54 +1000 (AEST) Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=informatik.wtf (client-ip=68.65.122.24; helo=new-02.privateemail.com; envelope-from=cmr@informatik.wtf; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=informatik.wtf Received: from NEW-02.privateemail.com (new-02.privateemail.com [68.65.122.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 44cwKY4WB3z9sMx for ; Mon, 8 Apr 2019 13:05:51 +1000 (AEST) Received: from MTA-07-1.privateemail.com (unknown [10.20.147.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by NEW-02.privateemail.com (Postfix) with ESMTPS id 83C8F60769; Mon, 8 Apr 2019 03:05:48 +0000 (UTC) Received: from MTA-07.privateemail.com (localhost [127.0.0.1]) by MTA-07.privateemail.com (Postfix) with ESMTP id 5E6CB60034; Sun, 7 Apr 2019 23:05:48 -0400 (EDT) Received: from wrwlf0000.attlocal.net (unknown [10.20.151.240]) by MTA-07.privateemail.com (Postfix) with ESMTPA id E31D060043; Mon, 8 Apr 2019 03:05:47 +0000 (UTC) From: "Christopher M. Riedl" To: linuxppc-dev@ozlabs.org Subject: [PATCH v2] powerpc/xmon: add read-only mode Date: Sun, 7 Apr 2019 22:08:04 -0500 Message-Id: <20190408030804.5805-1-cmr@informatik.wtf> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Virus-Scanned: ClamAV using ClamSMTP X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Christopher M. Riedl" , andrew.donnellan@au1.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Operations which write to memory and special purpose registers should be restricted on systems with integrity guarantees (such as Secure Boot) and, optionally, to avoid self-destructive behaviors. Add a config option, XMON_RW, to control default xmon behavior along with kernel cmdline options xmon=ro and xmon=rw for explicit control. Use XMON_RW instead of XMON in the condition to set PAGE_KERNEL_TEXT to allow xmon in read-only mode alongside write-protected kernel text. XMON_RW defaults to !STRICT_KERNEL_RWX. The following xmon operations are affected: memops: disable memmove disable memset disable memzcan memex: no-op'd mwrite super_regs: no-op'd write_spr bpt_cmds: disable proc_call: disable Signed-off-by: Christopher M. Riedl --- v1->v2: Use bool type for xmon_is_ro flag Replace XMON_RO with XMON_RW config option Make XMON_RW dependent on STRICT_KERNEL_RWX Use XMON_RW to control PAGE_KERNEL_TEXT Add printf in xmon read-only mode when dropping/skipping writes Disable memzcan (zero-fill memop) in xmon read-only mode arch/powerpc/Kconfig.debug | 10 +++++ arch/powerpc/include/asm/book3s/32/pgtable.h | 5 ++- arch/powerpc/include/asm/book3s/64/pgtable.h | 5 ++- arch/powerpc/include/asm/nohash/pgtable.h | 5 ++- arch/powerpc/xmon/xmon.c | 42 ++++++++++++++++++++ 5 files changed, 61 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug index 4e00cb0a5464..0c7f21476018 100644 --- a/arch/powerpc/Kconfig.debug +++ b/arch/powerpc/Kconfig.debug @@ -117,6 +117,16 @@ config XMON_DISASSEMBLY to say Y here, unless you're building for a memory-constrained system. +config XMON_RW + bool "Allow xmon read and write operations" + depends on XMON + default !STRICT_KERNEL_RWX + help + Allow xmon to read and write to memory and special-purpose registers. + Conversely, prevent xmon write access when set to N. Read and write + access can also be explicitly controlled with 'xmon=rw' or 'xmon=ro' + (read-only) cmdline options. Default is !STRICT_KERNEL_RWX. + config DEBUGGER bool depends on KGDB || XMON diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h index aa8406b8f7ba..615144ad667d 100644 --- a/arch/powerpc/include/asm/book3s/32/pgtable.h +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h @@ -86,8 +86,9 @@ static inline bool pte_user(pte_t pte) * set breakpoints anywhere, so don't write protect the kernel text * on platforms where such control is possible. */ -#if defined(CONFIG_KGDB) || defined(CONFIG_XMON) || defined(CONFIG_BDI_SWITCH) ||\ - defined(CONFIG_KPROBES) || defined(CONFIG_DYNAMIC_FTRACE) +#if defined(CONFIG_KGDB) || defined(CONFIG_XMON_RW) || \ + defined(CONFIG_BDI_SWITCH) || defined(CONFIG_KPROBES) || \ + defined(CONFIG_DYNAMIC_FTRACE) #define PAGE_KERNEL_TEXT PAGE_KERNEL_X #else #define PAGE_KERNEL_TEXT PAGE_KERNEL_ROX diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index 581f91be9dd4..bc4655122f6b 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -168,8 +168,9 @@ * set breakpoints anywhere, so don't write protect the kernel text * on platforms where such control is possible. */ -#if defined(CONFIG_KGDB) || defined(CONFIG_XMON) || defined(CONFIG_BDI_SWITCH) || \ - defined(CONFIG_KPROBES) || defined(CONFIG_DYNAMIC_FTRACE) +#if defined(CONFIG_KGDB) || defined(CONFIG_XMON_RW) || \ + defined(CONFIG_BDI_SWITCH) || defined(CONFIG_KPROBES) || \ + defined(CONFIG_DYNAMIC_FTRACE) #define PAGE_KERNEL_TEXT PAGE_KERNEL_X #else #define PAGE_KERNEL_TEXT PAGE_KERNEL_ROX diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h index 1ca1c1864b32..c052931bd243 100644 --- a/arch/powerpc/include/asm/nohash/pgtable.h +++ b/arch/powerpc/include/asm/nohash/pgtable.h @@ -22,8 +22,9 @@ * set breakpoints anywhere, so don't write protect the kernel text * on platforms where such control is possible. */ -#if defined(CONFIG_KGDB) || defined(CONFIG_XMON) || defined(CONFIG_BDI_SWITCH) ||\ - defined(CONFIG_KPROBES) || defined(CONFIG_DYNAMIC_FTRACE) +#if defined(CONFIG_KGDB) || defined(CONFIG_XMON_RW) || \ + defined(CONFIG_BDI_SWITCH) || defined(CONFIG_KPROBES) || \ + defined(CONFIG_DYNAMIC_FTRACE) #define PAGE_KERNEL_TEXT PAGE_KERNEL_X #else #define PAGE_KERNEL_TEXT PAGE_KERNEL_ROX diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index a0f44f992360..224ca0b3506b 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -80,6 +80,7 @@ static int set_indicator_token = RTAS_UNKNOWN_SERVICE; #endif static unsigned long in_xmon __read_mostly = 0; static int xmon_on = IS_ENABLED(CONFIG_XMON_DEFAULT); +static bool xmon_is_ro = !IS_ENABLED(CONFIG_XMON_RW); static unsigned long adrs; static int size = 1; @@ -202,6 +203,8 @@ static void dump_tlb_book3e(void); #define GETWORD(v) (((v)[0] << 24) + ((v)[1] << 16) + ((v)[2] << 8) + (v)[3]) #endif +static const char *xmon_is_ro_warn = "xmon read-only mode: skipping write\n"; + static char *help_string = "\ Commands:\n\ b show breakpoints\n\ @@ -989,6 +992,10 @@ cmds(struct pt_regs *excp) memlocate(); break; case 'z': + if (xmon_is_ro) { + printf(xmon_is_ro_warn); + break; + } memzcan(); break; case 'i': @@ -1042,6 +1049,10 @@ cmds(struct pt_regs *excp) set_lpp_cmd(); break; case 'b': + if (xmon_is_ro) { + printf(xmon_is_ro_warn); + break; + } bpt_cmds(); break; case 'C': @@ -1055,6 +1066,10 @@ cmds(struct pt_regs *excp) bootcmds(); break; case 'p': + if (xmon_is_ro) { + printf(xmon_is_ro_warn); + break; + } proccall(); break; case 'P': @@ -1777,6 +1792,11 @@ read_spr(int n, unsigned long *vp) static void write_spr(int n, unsigned long val) { + if (xmon_is_ro) { + printf(xmon_is_ro_warn); + return; + } + if (setjmp(bus_error_jmp) == 0) { catch_spr_faults = 1; sync(); @@ -2016,6 +2036,12 @@ mwrite(unsigned long adrs, void *buf, int size) char *p, *q; n = 0; + + if (xmon_is_ro) { + printf(xmon_is_ro_warn); + return n; + } + if (setjmp(bus_error_jmp) == 0) { catch_memory_errors = 1; sync(); @@ -2884,9 +2910,17 @@ memops(int cmd) scanhex((void *)&mcount); switch( cmd ){ case 'm': + if (xmon_is_ro) { + printf(xmon_is_ro_warn); + break; + } memmove((void *)mdest, (void *)msrc, mcount); break; case 's': + if (xmon_is_ro) { + printf(xmon_is_ro_warn); + break; + } memset((void *)mdest, mval, mcount); break; case 'd': @@ -3796,6 +3830,14 @@ static int __init early_parse_xmon(char *p) } else if (strncmp(p, "on", 2) == 0) { xmon_init(1); xmon_on = 1; + } else if (strncmp(p, "rw", 2) == 0) { + xmon_init(1); + xmon_on = 1; + xmon_is_ro = false; + } else if (strncmp(p, "ro", 2) == 0) { + xmon_init(1); + xmon_on = 1; + xmon_is_ro = true; } else if (strncmp(p, "off", 3) == 0) xmon_on = 0; else -- 2.21.0