Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933205AbbGGUWZ (ORCPT ); Tue, 7 Jul 2015 16:22:25 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:51197 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932661AbbGGUU6 (ORCPT ); Tue, 7 Jul 2015 16:20:58 -0400 From: Yinghai Lu To: Kees Cook , "H. Peter Anvin" , Baoquan He Cc: linux-kernel@vger.kernel.org, Yinghai Lu Subject: [PATCH 06/42] x86, kaslr: Consolidate mem_avoid array filling Date: Tue, 7 Jul 2015 13:19:52 -0700 Message-Id: <1436300428-21163-7-git-send-email-yinghai@kernel.org> X-Mailer: git-send-email 1.8.4.5 In-Reply-To: <1436300428-21163-1-git-send-email-yinghai@kernel.org> References: <1436300428-21163-1-git-send-email-yinghai@kernel.org> X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4910 Lines: 130 We are going to support kaslr with 64bit above 4G, and new random output buffer could be anywhere. mem_avoid array is used for kaslr to search new output buffer. Current code only track range that is after output+output_run_size. We need to track all range instead of just after output+output_run_size. Current code has first entry is extra bytes after input+input_size, and it is according to output_run_size. Other entries are for initrd, cmdline, and heap/stack for ZO running. At first, check the first entry that should be in the mem_avoid array. Now ZO sit end of the buffer always, we can find out where is ZO text and data/bss etc. output+run_size | 0 output input input+input_size | output+init_size | | | | | | |-----|-----------------|--|---------------|------|---|----------| | | output+init_size-ZO_SIZE output+output_size [output, output+init_size) is the buffer for decompress. [output, output+run_size) is for VO run size. [output, output+output_size) is (VO (vmlinux after objcopy) plus relocs) [output+init_size-ZO_SIZE, output+init_size) is copied ZO. [input, input+input_size) is copied compressed (VO (vmlinux after objcopy) plus relocs), not the ZO. [input+input_size, output+init_size) is [_text, _end) for ZO. that could be first range in mem_avoid. That new first entry already include heap and stack for ZO running. So we don't need to put them separatedly into mem_avoid array. Also we need to put [input, input+input_size) in mem_avoid array, ant it is connected to first one, so merge them. At last we need to put boot_params into the mem_avoid too. As with 64bit bootloader could put it anywhere. After those changes, we have all range needed to be avoided in mem_avoid array. Cc: Kees Cook Signed-off-by: Yinghai Lu --- arch/x86/boot/compressed/aslr.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c index 0e1dac0..d753fb3 100644 --- a/arch/x86/boot/compressed/aslr.c +++ b/arch/x86/boot/compressed/aslr.c @@ -109,7 +109,7 @@ struct mem_vector { unsigned long size; }; -#define MEM_AVOID_MAX 5 +#define MEM_AVOID_MAX 4 static struct mem_vector mem_avoid[MEM_AVOID_MAX]; static bool mem_contains(struct mem_vector *region, struct mem_vector *item) @@ -135,21 +135,22 @@ static bool mem_overlaps(struct mem_vector *one, struct mem_vector *two) } static void mem_avoid_init(unsigned long input, unsigned long input_size, - unsigned long output, unsigned long output_run_size) + unsigned long output) { + unsigned long init_size = real_mode->hdr.init_size; u64 initrd_start, initrd_size; u64 cmd_line, cmd_line_size; - unsigned long unsafe, unsafe_len; char *ptr; /* * Avoid the region that is unsafe to overlap during - * decompression (see calculations at top of misc.c). + * decompression. + * As we already move ZO (arch/x86/boot/compressed/vmlinux) + * to the end of buffer, [input+input_size, output+init_size) + * has [_text, _end) for ZO. */ - unsafe_len = (output_run_size >> 12) + 32768 + 18; - unsafe = (unsigned long)input + input_size - unsafe_len; - mem_avoid[0].start = unsafe; - mem_avoid[0].size = unsafe_len; + mem_avoid[0].start = input; + mem_avoid[0].size = (output + init_size) - input; /* Avoid initrd. */ initrd_start = (u64)real_mode->ext_ramdisk_image << 32; @@ -169,13 +170,9 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size, mem_avoid[2].start = cmd_line; mem_avoid[2].size = cmd_line_size; - /* Avoid heap memory. */ - mem_avoid[3].start = (unsigned long)free_mem_ptr; - mem_avoid[3].size = BOOT_HEAP_SIZE; - - /* Avoid stack memory. */ - mem_avoid[4].start = (unsigned long)free_mem_end_ptr; - mem_avoid[4].size = BOOT_STACK_SIZE; + /* Avoid params */ + mem_avoid[3].start = (unsigned long)real_mode; + mem_avoid[3].size = sizeof(*real_mode); } /* Does this memory vector overlap a known avoided area? */ @@ -319,7 +316,7 @@ unsigned char *choose_kernel_location(unsigned char *input, /* Record the various known unsafe memory ranges. */ mem_avoid_init((unsigned long)input, input_size, - (unsigned long)output, output_run_size); + (unsigned long)output); /* Walk e820 and find a random address. */ random = find_random_addr(choice, output_run_size); -- 1.8.4.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/