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e6023367d7
When choosing a random address, the current implementation does not take into
account the reversed space for .bss and .brk sections. Thus the relocated kernel
may overlap other components in memory. Here is an example of the overlap from a
x86_64 kernel in qemu (the ranges of physical addresses are presented):
Physical Address
0x0fe00000 --+--------------------+ <-- randomized base
/ | relocated kernel |
vmlinux.bin | (from vmlinux.bin) |
0x1336d000 (an ELF file) +--------------------+--
\ | | \
0x1376d870 --+--------------------+ |
| relocs table | |
0x13c1c2a8 +--------------------+ .bss and .brk
| | |
0x13ce6000 +--------------------+ |
| | /
0x13f77000 | initrd |--
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0x13fef374 +--------------------+
The initrd image will then be overwritten by the memset during early
initialization:
[ 1.655204] Unpacking initramfs...
[ 1.662831] Initramfs unpacking failed: junk in compressed archive
This patch prevents the above situation by requiring a larger space when looking
for a random kernel base, so that existing logic can effectively avoids the
overlap.
[kees: switched to perl to avoid hex translation pain in mawk vs gawk]
[kees: calculated overlap without relocs table]
Fixes: 82fa9637a2 ("x86, kaslr: Select random position from e820 maps")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Junjie Mao <eternal.n08@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1414762838-13067-1-git-send-email-eternal.n08@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
105 lines
2.8 KiB
C
105 lines
2.8 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright (C) 2009 Intel Corporation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version
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* 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* H. Peter Anvin <hpa@linux.intel.com>
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*
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* ----------------------------------------------------------------------- */
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/*
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* Compute the desired load offset from a compressed program; outputs
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* a small assembly wrapper with the appropriate symbols defined.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <inttypes.h>
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#include <tools/le_byteshift.h>
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int main(int argc, char *argv[])
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{
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uint32_t olen;
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long ilen;
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unsigned long offs;
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unsigned long run_size;
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FILE *f = NULL;
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int retval = 1;
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if (argc < 3) {
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fprintf(stderr, "Usage: %s compressed_file run_size\n",
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argv[0]);
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goto bail;
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}
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/* Get the information for the compressed kernel image first */
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f = fopen(argv[1], "r");
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if (!f) {
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perror(argv[1]);
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goto bail;
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}
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if (fseek(f, -4L, SEEK_END)) {
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perror(argv[1]);
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}
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if (fread(&olen, sizeof(olen), 1, f) != 1) {
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perror(argv[1]);
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goto bail;
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}
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ilen = ftell(f);
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olen = get_unaligned_le32(&olen);
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/*
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* Now we have the input (compressed) and output (uncompressed)
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* sizes, compute the necessary decompression offset...
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*/
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offs = (olen > ilen) ? olen - ilen : 0;
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offs += olen >> 12; /* Add 8 bytes for each 32K block */
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offs += 64*1024 + 128; /* Add 64K + 128 bytes slack */
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offs = (offs+4095) & ~4095; /* Round to a 4K boundary */
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run_size = atoi(argv[2]);
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printf(".section \".rodata..compressed\",\"a\",@progbits\n");
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printf(".globl z_input_len\n");
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printf("z_input_len = %lu\n", ilen);
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printf(".globl z_output_len\n");
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printf("z_output_len = %lu\n", (unsigned long)olen);
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printf(".globl z_extract_offset\n");
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printf("z_extract_offset = 0x%lx\n", offs);
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/* z_extract_offset_negative allows simplification of head_32.S */
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printf(".globl z_extract_offset_negative\n");
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printf("z_extract_offset_negative = -0x%lx\n", offs);
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printf(".globl z_run_size\n");
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printf("z_run_size = %lu\n", run_size);
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printf(".globl input_data, input_data_end\n");
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printf("input_data:\n");
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printf(".incbin \"%s\"\n", argv[1]);
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printf("input_data_end:\n");
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retval = 0;
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bail:
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if (f)
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fclose(f);
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return retval;
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}
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