Taint tracking side channels

flows.c

==> flow0.c <==
#include<string.h>
#include<stdio.h>
#include<assert.h>

#define HIGH 0
#define LOW 1

void sha1_hex(char* pwd, size_t co,char *hashed_pwd){
    assert (co<9);
    assert (pwd);
    printf ("Pass <%s> received of len %d\n", pwd,strlen(pwd));
    strcpy(hashed_pwd,"16bba41ffc0a0f3b9671422a4e66be125");
}

int main() { 
 char pwd[9];
 char hashed_pwd[41];
 char msg[400];
 int i=0;

 for( i=0; read(HIGH, &pwd[i], 1) == 1 && pwd[i] != 0 && i < 8; i++);
 pwd[i]=0;

 sha1_hex(pwd,i,hashed_pwd);

 strcpy(msg, "INSERT INTO passwd (user, passwd) VALUES ('root', '");
 strcat(msg, hashed_pwd);
 strcat(msg, "');");
 write(LOW, msg, strlen(msg));  
}




==> flow1.c <==
int
main ()
{
  char input;
  char output;
  read (HIGH, &input, 1);    //"SECRET!"
  output = input;   //memcpy(&output,&input,1);
  write (LOW, &output, 1);
}

==> flow2.c <==
int
main ()
{
  unsigned char input;
  unsigned char output;
  read (HIGH, &input, 1);	//input = getchar()
  switch (input)
    {
    case 0:
      output = 0;
      break;
    case 1:
      output = 1;
      break;
    case 2:
      output = 2;
      break;
    case 3:
      output = 3;
      break;
    case 4:
      output = 4;
      break;
    case 5:
      output = 5;
      break;
    case 6:
      output = 6;
      break;
    case 7:
      output = 7;
      break;
    case 8:
      output = 8;
      break;
    case 9:
      output = 9;
      break;
    case 10:
      output = 10;
      break;
    case 11:
      output = 11;
      break;
    case 12:
      output = 12;
      break;
    case 13:
      output = 13;
      break;
    case 14:
      output = 14;
      break;
    case 15:
      output = 15;
      break;
    case 16:
      output = 16;
      break;
    case 17:
      output = 17;
      break;
    case 18:
      output = 18;
      break;
    case 19:
      output = 19;
      break;
    case 20:
      output = 20;
      break;
    case 21:
      output = 21;
      break;
    case 22:
      output = 22;
      break;
    case 23:
      output = 23;
      break;
    case 24:
      output = 24;
      break;
    case 25:
      output = 25;
      break;
    case 26:
      output = 26;
      break;
    case 27:
      output = 27;
      break;
    case 28:
      output = 28;
      break;
    case 29:
      output = 29;
      break;
    case 30:
      output = 30;
      break;
    case 31:
      output = 31;
      break;
    case 32:
      output = 32;
      break;
    case 33:
      output = 33;
      break;
    case 34:
      output = 34;
      break;
    case 35:
      output = 35;
      break;
    case 36:
      output = 36;
      break;
    case 37:
      output = 37;
      break;
    case 38:
      output = 38;
      break;
    case 39:
      output = 39;
      break;
    case 40:
      output = 40;
      break;
    case 41:
      output = 41;
      break;
    case 42:
      output = 42;
      break;
    case 43:
      output = 43;
      break;
    case 44:
      output = 44;
      break;
    case 45:
      output = 45;
      break;
    case 46:
      output = 46;
      break;
    case 47:
      output = 47;
      break;
    case 48:
      output = 48;
      break;
    case 49:
      output = 49;
      break;
    case 50:
      output = 50;
      break;
    case 51:
      output = 51;
      break;
    case 52:
      output = 52;
      break;
    case 53:
      output = 53;
      break;
    case 54:
      output = 54;
      break;
    case 55:
      output = 55;
      break;
    case 56:
      output = 56;
      break;
    case 57:
      output = 57;
      break;
    case 58:
      output = 58;
      break;
    case 59:
      output = 59;
      break;
    case 60:
      output = 60;
      break;
    case 61:
      output = 61;
      break;
    case 62:
      output = 62;
      break;
    case 63:
      output = 63;
      break;
    case 64:
      output = 64;
      break;
    case 65:
      output = 65;
      break;
    case 66:
      output = 66;
      break;
    case 67:
      output = 67;
      break;
    case 68:
      output = 68;
      break;
    case 69:
      output = 69;
      break;
    case 70:
      output = 70;
      break;
    case 71:
      output = 71;
      break;
    case 72:
      output = 72;
      break;
    case 73:
      output = 73;
      break;
    case 74:
      output = 74;
      break;
    case 75:
      output = 75;
      break;
    case 76:
      output = 76;
      break;
    case 77:
      output = 77;
      break;
    case 78:
      output = 78;
      break;
    case 79:
      output = 79;
      break;
    case 80:
      output = 80;
      break;
    case 81:
      output = 81;
      break;
    case 82:
      output = 82;
      break;
    case 83:
      output = 83;
      break;
    case 84:
      output = 84;
      break;
    case 85:
      output = 85;
      break;
    case 86:
      output = 86;
      break;
    case 87:
      output = 87;
      break;
    case 88:
      output = 88;
      break;
    case 89:
      output = 89;
      break;
    case 90:
      output = 90;
      break;
    case 91:
      output = 91;
      break;
    case 92:
      output = 92;
      break;
    case 93:
      output = 93;
      break;
    case 94:
      output = 94;
      break;
    case 95:
      output = 95;
      break;
    case 96:
      output = 96;
      break;
    case 97:
      output = 97;
      break;
    case 98:
      output = 98;
      break;
    case 99:
      output = 99;
      break;
    case 100:
      output = 100;
      break;
    case 101:
      output = 101;
      break;
    case 102:
      output = 102;
      break;
    case 103:
      output = 103;
      break;
    case 104:
      output = 104;
      break;
    case 105:
      output = 105;
      break;
    case 106:
      output = 106;
      break;
    case 107:
      output = 107;
      break;
    case 108:
      output = 108;
      break;
    case 109:
      output = 109;
      break;
    case 110:
      output = 110;
      break;
    case 111:
      output = 111;
      break;
    case 112:
      output = 112;
      break;
    case 113:
      output = 113;
      break;
    case 114:
      output = 114;
      break;
    case 115:
      output = 115;
      break;
    case 116:
      output = 116;
      break;
    case 117:
      output = 117;
      break;
    case 118:
      output = 118;
      break;
    case 119:
      output = 119;
      break;
    case 120:
      output = 120;
      break;
    case 121:
      output = 121;
      break;
    case 122:
      output = 122;
      break;
    case 123:
      output = 123;
      break;
    case 124:
      output = 124;
      break;
    case 125:
      output = 125;
      break;
    case 126:
      output = 126;
      break;
    case 127:
      output = 127;
      break;
    case 128:
      output = 128;
      break;
    case 129:
      output = 129;
      break;
    case 130:
      output = 130;
      break;
    case 131:
      output = 131;
      break;
    case 132:
      output = 132;
      break;
    case 133:
      output = 133;
      break;
    case 134:
      output = 134;
      break;
    case 135:
      output = 135;
      break;
    case 136:
      output = 136;
      break;
    case 137:
      output = 137;
      break;
    case 138:
      output = 138;
      break;
    case 139:
      output = 139;
      break;
    case 140:
      output = 140;
      break;
    case 141:
      output = 141;
      break;
    case 142:
      output = 142;
      break;
    case 143:
      output = 143;
      break;
    case 144:
      output = 144;
      break;
    case 145:
      output = 145;
      break;
    case 146:
      output = 146;
      break;
    case 147:
      output = 147;
      break;
    case 148:
      output = 148;
      break;
    case 149:
      output = 149;
      break;
    case 150:
      output = 150;
      break;
    case 151:
      output = 151;
      break;
    case 152:
      output = 152;
      break;
    case 153:
      output = 153;
      break;
    case 154:
      output = 154;
      break;
    case 155:
      output = 155;
      break;
    case 156:
      output = 156;
      break;
    case 157:
      output = 157;
      break;
    case 158:
      output = 158;
      break;
    case 159:
      output = 159;
      break;
    case 160:
      output = 160;
      break;
    case 161:
      output = 161;
      break;
    case 162:
      output = 162;
      break;
    case 163:
      output = 163;
      break;
    case 164:
      output = 164;
      break;
    case 165:
      output = 165;
      break;
    case 166:
      output = 166;
      break;
    case 167:
      output = 167;
      break;
    case 168:
      output = 168;
      break;
    case 169:
      output = 169;
      break;
    case 170:
      output = 170;
      break;
    case 171:
      output = 171;
      break;
    case 172:
      output = 172;
      break;
    case 173:
      output = 173;
      break;
    case 174:
      output = 174;
      break;
    case 175:
      output = 175;
      break;
    case 176:
      output = 176;
      break;
    case 177:
      output = 177;
      break;
    case 178:
      output = 178;
      break;
    case 179:
      output = 179;
      break;
    case 180:
      output = 180;
      break;
    case 181:
      output = 181;
      break;
    case 182:
      output = 182;
      break;
    case 183:
      output = 183;
      break;
    case 184:
      output = 184;
      break;
    case 185:
      output = 185;
      break;
    case 186:
      output = 186;
      break;
    case 187:
      output = 187;
      break;
    case 188:
      output = 188;
      break;
    case 189:
      output = 189;
      break;
    case 190:
      output = 190;
      break;
    case 191:
      output = 191;
      break;
    case 192:
      output = 192;
      break;
    case 193:
      output = 193;
      break;
    case 194:
      output = 194;
      break;
    case 195:
      output = 195;
      break;
    case 196:
      output = 196;
      break;
    case 197:
      output = 197;
      break;
    case 198:
      output = 198;
      break;
    case 199:
      output = 199;
      break;
    case 200:
      output = 200;
      break;
    case 201:
      output = 201;
      break;
    case 202:
      output = 202;
      break;
    case 203:
      output = 203;
      break;
    case 204:
      output = 204;
      break;
    case 205:
      output = 205;
      break;
    case 206:
      output = 206;
      break;
    case 207:
      output = 207;
      break;
    case 208:
      output = 208;
      break;
    case 209:
      output = 209;
      break;
    case 210:
      output = 210;
      break;
    case 211:
      output = 211;
      break;
    case 212:
      output = 212;
      break;
    case 213:
      output = 213;
      break;
    case 214:
      output = 214;
      break;
    case 215:
      output = 215;
      break;
    case 216:
      output = 216;
      break;
    case 217:
      output = 217;
      break;
    case 218:
      output = 218;
      break;
    case 219:
      output = 219;
      break;
    case 220:
      output = 220;
      break;
    case 221:
      output = 221;
      break;
    case 222:
      output = 222;
      break;
    case 223:
      output = 223;
      break;
    case 224:
      output = 224;
      break;
    case 225:
      output = 225;
      break;
    case 226:
      output = 226;
      break;
    case 227:
      output = 227;
      break;
    case 228:
      output = 228;
      break;
    case 229:
      output = 229;
      break;
    case 230:
      output = 230;
      break;
    case 231:
      output = 231;
      break;
    case 232:
      output = 232;
      break;
    case 233:
      output = 233;
      break;
    case 234:
      output = 234;
      break;
    case 235:
      output = 235;
      break;
    case 236:
      output = 236;
      break;
    case 237:
      output = 237;
      break;
    case 238:
      output = 238;
      break;
    case 239:
      output = 239;
      break;
    case 240:
      output = 240;
      break;
    case 241:
      output = 241;
      break;
    case 242:
      output = 242;
      break;
    case 243:
      output = 243;
      break;
    case 244:
      output = 244;
      break;
    case 245:
      output = 245;
      break;
    case 246:
      output = 246;
      break;
    case 247:
      output = 247;
      break;
    case 248:
      output = 248;
      break;
    case 249:
      output = 249;
      break;
    case 250:
      output = 250;
      break;
    case 251:
      output = 251;
      break;
    case 252:
      output = 252;
      break;
    case 253:
      output = 253;
      break;
    case 254:
      output = 254;
      break;
    case 255:
      output = 255;
      break;
    }
  write (LOW, &output, 1);
}

==> flow3.c <==

int
main ()
{
  unsigned char array[256] = { 0 };	//256 zeros
  unsigned char input;
  unsigned char output;
  read (HIGH, &input, 1);	//read a char from a HIGH file
  array[input] = 1;
  for (output = 0; !array[output]; output++);	//Count zeros until first non-zero
  write (LOW, &output, 1);	//write output to a LOW file
}