236 lines
7.6 KiB
Bash
236 lines
7.6 KiB
Bash
#!/bin/bash
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# fips_crypto_hmac.sh
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#
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# Author : Rohit Kothari (r.kothari@samsung.com)
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# Created on : 14 Feb 2014
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# Copyright (c) Samsung Electronics 2014
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# Given a vmlinux file and a System.map, this scripts finds bytes belonging to
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# Kernel Crypto within vmlinux file.(Under section .text, .init.text, .exit.text and .rodata)
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# After collecting all the bytes, it calculates a hmac(sha256) on those bytes.
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# Generated hmac is put back into a crypto rodata variable within vmlinux file itself.
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# This makes the build time hmac available at runtime, for integrity check.
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#
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# To find crypto bytes, this scripts heavily relies on output of arm-eabi-readelf.
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# If the output of arm-eabi-readelf changes in future, this script might need changes.
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#
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# Pre-conditions : $READELF, $HOSTCC variables are set.
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#
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#
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if test $# -ne 2; then
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echo "Usage: $0 vmlinux System.map"
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exit 1
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fi
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vmlinux_var=$1
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system_map_var=$2
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if [[ -z "$vmlinux_var" || -z "$system_map_var" || -z "$READELF" || -z "$HOSTCC" ]]; then
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echo "$0 : variables not set"
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exit 1
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fi
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if [[ ! -f $vmlinux_var || ! -f $system_map_var ]]; then
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echo "$0 : files does not exist"
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exit 1
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fi
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rm -f vmlinux.elf
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$READELF -S $vmlinux_var > vmlinux.elf
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retval=$?
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if [ $retval -ne 0 ]; then
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echo "$0 : $READELF returned error"
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exit 1
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fi
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declare -A array
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# FOR GENERIC CRYPTO FILES #awk fields to cut
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array[0]=".text first_crypto_text last_crypto_text \$5 \$6"
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array[1]=".rodata first_crypto_rodata last_crypto_rodata \$5 \$6"
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array[2]=".init.text first_crypto_init last_crypto_init \$4 \$5"
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array[3]=".exit.text first_crypto_exit last_crypto_exit \$4 \$5"
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# # FOR ASM CRYPTO FILES
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array[4]=".text first_crypto_asm_text last_crypto_asm_text \$5 \$6"
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array[5]=".rodata first_crypto_asm_rodata last_crypto_asm_rodata \$5 \$6"
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array[6]=".init.text first_crypto_asm_init last_crypto_asm_init \$4 \$5"
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array[7]=".exit.text first_crypto_asm_exit last_crypto_asm_exit \$4 \$5"
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rm -f offsets_sizes.txt
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#Addresses retrieved must be a valid hex
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reg='^[0-9A-Fa-f]+$'
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#Total bytes of all crypto sections scanned. Used later for error checking
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total_bytes=0;
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# For each type of Section :
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# first_addr = Address of first_crypto_text, first_crypto_rodata, etc.
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# last_addr = Address of last_crypto_text, last_crypto_rodata etc.
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# start_addr = Starting Address of a section within vmlinux
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# offset = Offset in vmlinux file where the section begins
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# file_offset = Offset in vmlinux file where the crypto bytes begins.
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# size = size of crypto bytes.
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# Output is offsets_sizes.txt, of the format
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# Section Name crypto_bytes_offset crypto_bytes_size
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# (in decimal) (in decimal)
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# .text 2531072 114576
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# .rodata 9289648 55388
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# : : :
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for i in "${array[@]}"; do
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var1=var2=var3=var4=var5=""
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first_addr=last_addr=start_addr=offset=file_offset=size=""
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k=1
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#This loop creates var1, var2 etc and set them to individual strings of a row in array
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for j in $i; do
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export var$k=$j
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let k+=1
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done
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first_addr=`cat $system_map_var|grep -w $var2|awk '{print $1}'`
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if [[ ! $first_addr =~ $reg ]]; then echo "$0 : first_addr invalid"; exit 1; fi
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last_addr=`cat $system_map_var|grep -w $var3|awk '{print $1}'`
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if [[ ! $last_addr =~ $reg ]]; then echo "$0 : last_addr invalid"; exit 1; fi
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start_addr=`cat vmlinux.elf |grep -w $var1|grep PROGBITS|awk '{print '$var4'}'`
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if [[ ! $start_addr =~ $reg ]]; then echo "$0 : start_addr invalid"; exit 1; fi
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offset=`cat vmlinux.elf |grep -w $var1|grep PROGBITS|awk '{print '$var5'}'`
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if [[ ! $offset =~ $reg ]]; then echo "$0 : offset invalid"; exit 1; fi
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if [[ $((16#$first_addr)) -lt $((16#$start_addr)) ]]; then echo "$0 : first_addr < start_addr"; exit 1; fi
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if [[ $((16#$last_addr)) -le $((16#$first_addr)) ]]; then echo "$0 : last_addr <= first_addr"; exit 1; fi
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file_offset=`expr $((16#$offset)) + $((16#$first_addr)) - $((16#$start_addr))`
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if [[ $file_offset -le 0 ]]; then echo "$0 : file_offset invalid"; exit 1; fi
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size=`expr $((16#$last_addr)) - $((16#$first_addr))`
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if [[ $size -le 0 ]]; then echo "$0 : crypto section size invalid"; exit 1; fi
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echo "$var1 " $file_offset " " $size >> offsets_sizes.txt
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let "total_bytes += `expr $((16#$last_addr)) - $((16#$first_addr))`"
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done
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if [[ ! -f offsets_sizes.txt ]]; then
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echo "$0 : offset_sizes.txt does not exist"
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exit 1
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fi
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rm -f fips_crypto_utils
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$HOSTCC -o fips_crypto_utils $srctree/scripts/fips_crypto_utils.c
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retval=$?
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if [ $retval -ne 0 ]; then
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echo "$0 : $HOSTCC returned error"
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exit 1
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fi
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rm -f builtime_bytes.txt #used for debugging
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rm -f builtime_bytes.bin #used for calculating hmac
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date_var=`date`
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echo "Created on : " $date_var > builtime_bytes.txt
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#Using offsets_sizes.txt, dump crypto bytes from vmlinux file into builtime_bytes.bin
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#Also gather printf's into builtime_bytes.txt, for debugging if required
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while read args; do
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./fips_crypto_utils -g $vmlinux_var $args builtime_bytes.bin >> builtime_bytes.txt
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retval=$?
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if [ $retval -ne 0 ]; then
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echo "$0 : fips_crypto_utils : unable to gather crypto bytes from vmlinux"
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exit 1
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fi
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echo "" >> builtime_bytes.txt
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done < offsets_sizes.txt # <================== offsets_sizes.txt
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if [[ ! -f builtime_bytes.bin ]]; then
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echo "$0 : builtime_bytes.bin does not exist"
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exit 1
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fi
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file_size=`cat builtime_bytes.bin| wc -c`
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# Make sure that file size of crypto_hmac.bin is as expected
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if [ $total_bytes -ne $file_size ]; then
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echo "$0: Bytes mismatch"
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exit 1
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fi
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key="The quick brown fox jumps over the lazy dog"
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# Now, generate the hmac.
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openssl dgst -sha256 -hmac "$key" -binary -out crypto_hmac.bin builtime_bytes.bin
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retval=$?
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if [ $retval -ne 0 ]; then
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echo "$0 : openssl dgst command returned error"
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exit 1
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fi
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# Just, for debugging, print the same hmac on console
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openssl dgst -sha256 -hmac "$key" builtime_bytes.bin
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retval=$?
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if [ $retval -ne 0 ]; then
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echo "$0 : openssl dgst command returned error"
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exit 1
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fi
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if [[ ! -f crypto_hmac.bin ]]; then
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echo "$0 : crypto_hmac.bin does not exist"
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exit 1
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fi
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file_size=`cat crypto_hmac.bin| wc -c`
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# hmac(sha256) produces 32 bytes of hmac
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if [ $file_size -ne 32 ]; then
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echo "$0: Unexpected size of Hash file : " $file_size
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exit 1
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fi
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# Now that we have the hmac, update this hmac into an rodata "builtime_crypto_hmac" varialble
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# in vmlinux file.
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# This variable has a place holder 32 bytes that will be over-written with generated hmac.
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# This way, this build time hmac, will be available as a read-only variable at run-time.
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first_addr=`cat $system_map_var|grep -w "builtime_crypto_hmac"|awk '{print $1}' `
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if [[ ! $first_addr =~ $reg ]]; then echo "$0 : first_addr of hmac variable invalid"; exit 1; fi
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start_addr=`cat vmlinux.elf |grep -w ".rodata"|grep PROGBITS|awk '{print $5}' `
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if [[ ! $start_addr =~ $reg ]]; then echo "$0 : start_addr of .rodata invalid"; exit 1; fi
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offset=`cat vmlinux.elf |grep -w ".rodata"|grep PROGBITS| awk '{print $6}' `
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if [[ ! $offset =~ $reg ]]; then echo "$0 : offset of .rodata invalid"; exit 1; fi
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if [[ $((16#$first_addr)) -le $((16#$start_addr)) ]]; then echo "$0 : hmac var first_addr <= start_addr"; exit 1; fi
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hmac_offset=`expr $((16#$offset)) + $((16#$first_addr)) - $((16#$start_addr))`
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if [[ $hmac_offset -le 0 ]]; then echo "$0 : hmac_offset invalid"; exit 1; fi
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# This does the actual update of hmac into vmlinux file, at given offset
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./fips_crypto_utils -u $vmlinux_var crypto_hmac.bin $hmac_offset
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retval=$?
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if [ $retval -ne 0 ]; then
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echo "$0 : fips_crypto_utils : unable to update hmac in vmlinux"
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exit 1
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fi
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rm -f crypto_hmac.bin
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rm -f builtime_bytes.txt
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rm -f builtime_bytes.bin
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rm -f fips_crypto_utils
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rm -f vmlinux.elf
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rm -f offsets_sizes.txt
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# And we are done...
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