scripts/fips_fmp_hmac.sh

   1 #!/bin/bash
   2
   3 # fips_fmp_hmac.sh
   4 #
   5 # Author     : Rohit Kothari (r.kothari@samsung.com)
   6 # Created on :  14 Feb 2014
   7 # Copyright (c) Samsung Electronics 2014
   8
   9 # Given a vmlinux file and a System.map, this scripts finds bytes belonging to
  10 # Kernel Crypto within vmlinux file.(Under section .text, .init.text, .exit.text and .rodata)
  11 # After collecting all the bytes, it calculates a hmac(sha256) on those bytes.
  12 # Generated hmac is put back into a fmp rodata variable within vmlinux file itself.
  13 # This makes the build time hmac available at runtime, for integrity check.
  14 #
  15 # To find fmp bytes, this scripts heavily relies on output of arm-eabi-readelf.
  16 # If the output of arm-eabi-readelf changes in future, this script might need changes.
  17 #
  18 # Pre-conditions : $READELF, $HOSTCC variables are set.
  19 #
  20 #
  21
  22 if test $# -ne 2; then
  23         echo "Usage: $0 vmlinux System.map"
  24         exit 1
  25 fi
  26
  27 vmlinux_var=$1
  28 system_map_var=$2
  29
  30 if [[ -z "$vmlinux_var" || -z "$system_map_var" || -z "$READELF" || -z "$HOSTCC" ]]; then
  31         echo "$0 : variables not set"
  32         exit 1
  33 fi
  34
  35 if [[ ! -f $vmlinux_var || ! -f $system_map_var  ]]; then
  36         echo "$0 : files does not exist"
  37         exit 1
  38 fi
  39
  40 rm -f vmlinux.elf
  41 $READELF -S $vmlinux_var > vmlinux.elf
  42
  43 retval=$?
  44 if [ $retval -ne 0 ]; then
  45         echo "$0 : $READELF returned error"
  46         exit 1
  47 fi
  48
  49 declare -A array
  50
  51 # FOR GENERIC CRYPTO FILES                         #awk fields to cut
  52 array[0]=".text first_fmp_text last_fmp_text \$5 \$6"
  53 array[1]=".rodata first_fmp_rodata last_fmp_rodata \$5 \$6"
  54 array[2]=".init.text first_fmp_init last_fmp_init \$4 \$5"
  55
  56 rm -f offsets_sizes.txt
  57
  58 #Addresses retrieved must be a valid hex
  59 reg='^[0-9A-Fa-f]+$'
  60
  61 #Total bytes of all fmp sections scanned. Used later for error checking
  62 total_bytes=0;
  63
  64 # For each type of Section :
  65 # first_addr  = Address of first_fmp_text, first_fmp_rodata, etc.
  66 # last_addr   = Address of last_fmp_text, last_fmp_rodata etc.
  67 # start_addr  = Starting Address of a section within vmlinux
  68 # offset      = Offset in vmlinux file where the section begins
  69 # file_offset = Offset in vmlinux file where the fmp bytes begins.
  70 # size        = size of fmp bytes.
  71
  72 # Output is offsets_sizes.txt, of the format
  73 #   Section Name   fmp_bytes_offse     fmp_bytes_size
  74 #                   (in decimal)        (in decimal)
  75 #      .text           2531072            114576
  76 #    .rodata           9289648             55388
  77 #      :                  :                  :
  78
  79 for i in "${array[@]}"; do
  80
  81         var1=var2=var3=var4=var5=""
  82         first_addr=last_addr=start_addr=offset=file_offset=size=""
  83         k=1
  84         #This loop creates var1, var2 etc and set them to individual strings of a row in array
  85         for j in $i; do
  86                 export var$k=$j
  87                 let k+=1
  88         done
  89
  90         first_addr=`cat $system_map_var|grep -w $var2|awk '{print $1}'`
  91         if  [[ ! $first_addr =~ $reg ]]; then echo "$0 : first_addr invalid"; exit 1; fi
  92
  93         last_addr=`cat $system_map_var|grep -w $var3|awk '{print $1}'`
  94         if  [[ ! $last_addr =~ $reg ]]; then echo "$0 : last_addr invalid"; exit 1; fi
  95
  96         start_addr=`cat vmlinux.elf |grep -w "$var1 "|grep PROGBITS|awk '{print '$var4'}'`
  97         if  [[ ! $start_addr =~ $reg ]]; then echo "$0 : start_addr invalid"; exit 1; fi
  98
  99         offset=`cat vmlinux.elf |grep -w "$var1 "|grep PROGBITS|awk '{print '$var5'}'`
 100         if  [[ ! $offset =~ $reg ]]; then echo "$0 : offset invalid"; exit 1; fi
 101
 102         if [[ $((16#$first_addr)) -lt $((16#$start_addr)) ]]; then echo "$0 : first_addr < start_addr"; exit 1; fi
 103
 104         if [[ $((16#$last_addr)) -le $((16#$first_addr)) ]]; then echo "$0 : last_addr <= first_addr"; exit 1; fi
 105
 106         file_offset=`expr $((16#$offset)) + $((16#$first_addr)) - $((16#$start_addr))`
 107         if  [[ $file_offset -le 0 ]]; then echo "$0 : file_offset invalid"; exit 1; fi
 108
 109         size=`expr $((16#$last_addr)) - $((16#$first_addr))`
 110         if  [[ $size -le 0 ]]; then echo "$0 : fmp section size invalid"; exit 1; fi
 111
 112         echo "$var1 " $file_offset " " $size >> offsets_sizes.txt
 113
 114         let "total_bytes += `expr $((16#$last_addr)) - $((16#$first_addr))`"
 115 done
 116
 117 if [[ ! -f offsets_sizes.txt ]]; then
 118         echo "$0 : offset_sizes.txt does not exist"
 119         exit 1
 120 fi
 121
 122 rm -f fips_fmp_utils
 123 $HOSTCC -o fips_fmp_utils $srctree/scripts/fips_fmp_utils.c
 124 retval=$?
 125 if [ $retval -ne 0 ]; then
 126         echo "$0 : $HOSTCC returned error"
 127         exit 1
 128 fi
 129
 130 rm -f builtime_bytes.txt #used for debugging
 131 rm -f builtime_bytes.bin #used for calculating hmac
 132
 133 date_var=`date`
 134 echo "Created on : " $date_var > builtime_bytes.txt
 135
 136 #Using offsets_sizes.txt, dump fmp bytes from vmlinux file into builtime_bytes.bin
 137 #Also gather printf's into builtime_bytes.txt, for debugging if required
 138 while read args; do
 139         ./fips_fmp_utils -g $vmlinux_var $args builtime_bytes.bin >> builtime_bytes.txt
 140         retval=$?
 141         if [ $retval -ne 0 ]; then
 142             echo "$0 : fips_fmp_utils : unable to gather fmp bytes from vmlinux"
 143             exit 1
 144         fi
 145         echo "" >> builtime_bytes.txt
 146 done < offsets_sizes.txt   # <================== offsets_sizes.txt
 147
 148 if [[ ! -f builtime_bytes.bin ]]; then
 149         echo "$0 : builtime_bytes.bin does not exist"
 150         exit 1
 151 fi
 152
 153 file_size=`cat builtime_bytes.bin| wc -c`
 154
 155 # Make sure that file size of fmp_hmac.bin is as expected
 156 if [ $total_bytes -ne $file_size ]; then
 157         echo "$0: Bytes mismatch"
 158         exit 1
 159 fi
 160
 161 key="The quick brown fox jumps over the lazy dog"
 162
 163 # Now, generate the hmac.
 164 openssl dgst -sha256 -hmac "$key" -binary -out fmp_hmac.bin builtime_bytes.bin
 165 retval=$?
 166 if [ $retval -ne 0 ]; then
 167         echo "$0 : openssl dgst command returned error"
 168         exit 1
 169 fi
 170
 171 # Just, for debugging, print the same hmac on console
 172 openssl dgst -sha256 -hmac "$key" builtime_bytes.bin
 173 retval=$?
 174 if [ $retval -ne 0 ]; then
 175         echo "$0 : openssl dgst command returned error"
 176         exit 1
 177 fi
 178
 179 if [[ ! -f fmp_hmac.bin ]]; then
 180         echo "$0 : fmp_hmac.bin does not exist"
 181         exit 1
 182 fi
 183
 184 file_size=`cat fmp_hmac.bin| wc -c`
 185
 186 # hmac(sha256) produces 32 bytes of hmac
 187 if [ $file_size -ne 32 ]; then
 188         echo "$0: Unexpected size of Hash file : " $file_size
 189         exit 1
 190 fi
 191
 192
 193 # Now that we have the hmac, update this hmac into an rodata "builtime_fmp_hmac" varialble
 194 # in vmlinux file.
 195 # This variable has a place holder 32 bytes that will be over-written with generated hmac.
 196 # This way, this build time hmac, will be available as a read-only variable at run-time.
 197
 198 first_addr=`cat $system_map_var|grep -w "builtime_fmp_hmac"|awk '{print $1}' `
 199 if  [[ ! $first_addr =~ $reg ]]; then echo "$0 : first_addr of hmac variable invalid"; exit 1; fi
 200
 201 start_addr=`cat vmlinux.elf |grep -w ".rodata"|grep PROGBITS|awk '{print $5}' `
 202 if  [[ ! $start_addr =~ $reg ]]; then echo "$0 : start_addr of .rodata invalid"; exit 1; fi
 203
 204 offset=`cat vmlinux.elf |grep -w ".rodata"|grep PROGBITS| awk '{print $6}' `
 205 if  [[ ! $offset =~ $reg ]]; then echo "$0 : offset of .rodata invalid"; exit 1; fi
 206
 207 if [[ $((16#$first_addr)) -le $((16#$start_addr)) ]]; then echo "$0 : hmac var first_addr <= start_addr"; exit 1; fi
 208
 209 hmac_offset=`expr $((16#$offset)) + $((16#$first_addr)) - $((16#$start_addr))`
 210 if  [[ $hmac_offset -le 0 ]]; then echo "$0 : hmac_offset invalid"; exit 1; fi
 211
 212 # This does the actual update of hmac into vmlinux file, at given offset
 213 ./fips_fmp_utils -u $vmlinux_var fmp_hmac.bin $hmac_offset
 214 retval=$?
 215 if [ $retval -ne 0 ]; then
 216         echo "$0 : fips_fmp_utils : unable to update hmac in vmlinux"
 217         exit 1
 218 fi
 219
 220 # rm -f fmp_hmac.bin
 221 # rm -f builtime_bytes.txt
 222 # rm -f builtime_bytes.bin
 223 # rm -f fips_fmp_utils
 224 # rm -f vmlinux.elf
 225 # rm -f offsets_sizes.txt
 226
 227 # And we are done...