Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1164249AbdDXCl3 (ORCPT ); Sun, 23 Apr 2017 22:41:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48990 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1164232AbdDXClV (ORCPT ); Sun, 23 Apr 2017 22:41:21 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 9143F7F4AC Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=bhe@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 9143F7F4AC From: Baoquan He To: linux-kernel@vger.kernel.org, keescook@chromium.org, mingo@kernel.org Cc: dave.jiang@intel.com, dan.j.williams@intel.com, hpa@zytor.com, tglx@linutronix.de, dyoung@redhat.com, Baoquan He , Ingo Molnar , x86@kernel.org, Yinghai Lu , Borislav Petkov Subject: [PATCH v2 2/3] KASLR: Handle memory limit specified by memmap and mem option Date: Mon, 24 Apr 2017 10:40:49 +0800 Message-Id: <1493001650-5793-3-git-send-email-bhe@redhat.com> In-Reply-To: <1493001650-5793-1-git-send-email-bhe@redhat.com> References: <1493001650-5793-1-git-send-email-bhe@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 24 Apr 2017 02:41:20 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4233 Lines: 152 Option mem= will limit the max address a system can use and any memory region above the limit will be removed. Furthermore, memmap=nn[KMG] which has no offset specified has the same behaviour as mem=. KASLR needs to consider this when choosing the random position for decompressing the kernel. This patch implements that. Signed-off-by: Baoquan He Cc: "H. Peter Anvin" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: x86@kernel.org Cc: Kees Cook Cc: Yinghai Lu Cc: Borislav Petkov --- arch/x86/boot/compressed/kaslr.c | 60 ++++++++++++++++++++++++++++++++-------- 1 file changed, 48 insertions(+), 12 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 6649ecd..34f66a5 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -79,6 +79,10 @@ int mem_avoid_memmap_index; extern unsigned long get_cmd_line_ptr(void); +/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */ +unsigned long long mem_limit = ULLONG_MAX; + + enum mem_avoid_index { MEM_AVOID_ZO_RANGE = 0, MEM_AVOID_INITRD, @@ -129,16 +133,22 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size) return -EINVAL; switch (*p) { - case '@': - /* Skip this region, usable */ - *start = 0; - *size = 0; - return 0; case '#': case '$': case '!': *start = memparse(p + 1, &p); return 0; + case '@': + /* memmap=nn@ss specifies usable region, should be skipped */ + *size = 0; + default: + /* + * If w/o offset, only size specified, memmap=nn[KMG] has the + * same behaviour as mem=nn[KMG]. It limits the max address + * system can use. Region above the limit should be avoided. + */ + *start = 0; + return 0; } return -EINVAL; @@ -164,9 +174,14 @@ static void mem_avoid_memmap(char *str) if (rc < 0) break; str = k; - /* A usable region that should not be skipped */ - if (size == 0) + + if (start == 0) { + /* Store the specified memory limit if size > 0 */ + if (size > 0) + mem_limit = size; + continue; + } mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start; mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size; @@ -191,6 +206,7 @@ static int handle_mem_memmap(void) size_t len = strlen((char *)args); char *tmp_cmdline; char *param, *val; + u64 mem_size; tmp_cmdline = malloc(COMMAND_LINE_SIZE); if (!tmp_cmdline ) @@ -213,8 +229,20 @@ static int handle_mem_memmap(void) return -1; } - if (!strcmp(param, "memmap")) + if (!strcmp(param, "memmap")) { mem_avoid_memmap(val); + } else if (!strcmp(param, "mem")) { + char *p = val; + + if (!strcmp(p, "nopentium")) + continue; + mem_size = memparse(p, &p); + if (mem_size == 0) { + free(tmp_cmdline); + return -EINVAL; + } + mem_limit = mem_size; + } } free(tmp_cmdline); @@ -451,7 +479,8 @@ static void process_e820_entry(struct boot_e820_entry *entry, { struct mem_vector region, overlap; struct slot_area slot_area; - unsigned long start_orig; + unsigned long start_orig, end; + struct boot_e820_entry cur_entry; /* Skip non-RAM entries. */ if (entry->type != E820_TYPE_RAM) @@ -465,8 +494,15 @@ static void process_e820_entry(struct boot_e820_entry *entry, if (entry->addr + entry->size < minimum) return; - region.start = entry->addr; - region.size = entry->size; + /* Ignore entries above memory limit */ + end = min(entry->size + entry->addr, mem_limit); + if (entry->addr >= end) + return; + cur_entry.addr = entry->addr; + cur_entry.size = end - entry->addr; + + region.start = cur_entry.addr; + region.size = cur_entry.size; /* Give up if slot area array is full. */ while (slot_area_index < MAX_SLOT_AREA) { @@ -480,7 +516,7 @@ static void process_e820_entry(struct boot_e820_entry *entry, region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN); /* Did we raise the address above this e820 region? */ - if (region.start > entry->addr + entry->size) + if (region.start > cur_entry.addr + cur_entry.size) return; /* Reduce size by any delta from the original address. */ -- 2.5.5