Improve key entry code

ChangeLog

@@ -1,3 +1,14 @@
+2018-03-02  Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Control.m:
+	* EcControl.m:
+	* EcProcess.h:
+	* EcProcess.m:
+	Allow EcControlKey to be an MD5 digest of the expected key, so we can
+	easily tell if the expected key was entered correctly.
+	Expose method to request entry of a hexadecimal key, with checking
+	against an MD5 digest of the expected value.
+
 2018-02-23  Richard Frith-Macdonald <rfm@gnu.org>
 
 	* AlarmTool.m: Add default values for arguments, suitable for sending

Control.m

@@ -32,144 +32,12 @@
 #import "EcProcess.h"
 
 #include <unistd.h>
-#include <termios.h>
 #include <stdio.h>
 
-static size_t
-trim(char *str)
-{
-  size_t        len = 0;
-  char          *frontp = str - 1;
-  char          *endp = NULL;
 
-  if (NULL == str || '\0' == str[0])
-    {
-      return 0;
-    }
-
-  len = strlen(str);
-  endp = str + len;
-
-  while (isspace(*(++frontp)))
-    ;
-
-  while (isspace(*(--endp)) && endp != frontp)
-    ;
-
-  if (str + len - 1 != endp)
-    {
-      *(endp + 1) = '\0';
-    }
-  else if (frontp != str && endp == frontp)
-    {
-      *str = '\0';
-    }
-
-  if (frontp != str)
-    {
-      endp = str;
-      while (*frontp)
-        {
-          *endp++ = *frontp++;
-        }
-      *endp = '\0';
-    }
-
-  return endp - str;
-}
-
-static BOOL
-getkey(NSString **key)
-{
-  FILE  *stream;
-  struct termios old;
-  struct termios new;
-  char          *one = NULL;
-  char          *two = NULL;
-
-#define MINKEY  16
-
-  /* Open the terminal
-   */
-  if ((stream = fopen("/dev/tty", "r+")) == NULL)
-    {
-      return NO;
-    }
-  /* Turn echoing off 
-   */
-  if (tcgetattr(fileno(stream), &old) != 0)
-    {
-      fclose(stream);
-      return NO;
-    }
-  new = old;
-  new.c_lflag &= ~ECHO;
-  if (tcsetattr (fileno(stream), TCSAFLUSH, &new) != 0)
-    {
-      fclose(stream);
-      return NO;
-    }
-
-  while (NULL == one || NULL == two)
-    {
-      int       olen = 0;
-      int       tlen = 0;
-
-      while (olen < MINKEY)
-        {
-          size_t    len = 0;
-
-          fprintf(stream, "\nPlease enter EcControlKey: ");
-          if (one != NULL) { free(one); one = NULL; }
-          olen = getline(&one, &len, stream);
-          if (olen < 0)
-            {
-              if (one != NULL) { free(one); one = NULL; }
-              fclose(stream);
-              return NO;
-            }
-          olen = trim(one);
-          if (olen < MINKEY)
-            {
-              fprintf(stream, "\nKey must be at least %u characters\n", MINKEY);
-            }
-        }
-  
-      while (0 == tlen)
-        {
-          size_t    len = 0;
-
-          fprintf(stream, "\nPlease re-enter to confirm: ");
-          if (two != NULL) { free(two); two = NULL; }
-          tlen = getline(&two, &len, stream);
-          if (tlen < 0)
-            {
-              if (one != NULL) { free(one); one = NULL; }
-              if (two != NULL) { free(two); two = NULL; }
-              fclose(stream);
-              return NO;
-            }
-          tlen = trim(two);
-        }
-
-      if (strcmp(one, two) != 0)
-        {
-          free(one); one = NULL;
-          free(two); two = NULL;
-          fprintf(stream, "\nKeys do not match, please try again.");
-        }
-    }
-  
-  /* Restore terminal. */
-  (void) tcsetattr(fileno(stream), TCSAFLUSH, &old);
-
-  *key = [NSString stringWithUTF8String: one];
-  free(one);
-  free(two);
-  fprintf(stream, "\nEcControlKey accepted.\n");
-  fclose(stream);
-  return YES;
-}
+#if     !defined(EC_DEFAULTS_PREFIX)
+#define EC_DEFAULTS_PREFIX nil
+#endif
 
 #if	!defined(EC_BASE_CLASS)
 #define	EC_BASE_CLASS	EcControl
@@ -203,6 +71,7 @@ main(int argc, char *argv[])
       NSString          *path = [[NSBundle mainBundle] executablePath];
       NSAutoreleasePool *inner = nil;
       BOOL              done = NO;
+      NSUInteger        index = NSNotFound;
       int               status = 0;
       NSTask	        *t;
 
@@ -210,20 +79,43 @@ main(int argc, char *argv[])
 
       if ([pArgs containsObject: @"--Watcher"] == NO)
         {
-          /* In the top level task ... set flags to create a subtask
-           * to act as a watcher for other tasks, and once that has
-           * been created, exit to leave it running as a daemon.
-           */
-          if ([[NSUserDefaults standardUserDefaults] boolForKey:
-            @"EcControlKey"] == YES)
+          NSUserDefaults        *defs;
+          NSString              *str;
+
+          defs = [NSUserDefaults standardUserDefaults];
+          str = [defs stringForKey: @"EcControlKey"];
+          if ([str length] == 32 || [str boolValue] == YES)
             {
-              if (getkey(&key) == NO)
+              NSData    *digest = nil;
+
+              if ([str length] == 32)
+                {
+                  /* Check that the 32 character value is hex digits,
+                   * in which case it should be the MD5 digest of the
+                   * actual key to be entered.
+                   */
+                  digest = AUTORELEASE([[NSData alloc]
+                    initWithHexadecimalRepresentation: str]);
+                  if ([digest length] != 16)
+                    {
+                      NSLog(@"Bad values specified in EcControlKey... abort");
+                      exit(1);
+                    }
+                }
+              key = [EcProcess ecGetKey: "EcControlKey"
+                                   size: 32
+                                    md5: digest];
+              if (nil == key)
                 {
                   NSLog(@"Failed to read EcControlKey from terminal ... abort");
                   exit(1);
                 }
             }
 
+          /* In the top level task ... set flags to create a subtask
+           * to act as a watcher for other tasks, and once that has
+           * been created, exit to leave it running as a daemon.
+           */
           [args addObject: @"--Watcher"];
           t = [NSTask new];
           NS_DURING
@@ -267,8 +159,26 @@ main(int argc, char *argv[])
 
       /* Set args to tell subtask task not to make itself a daemon
        */
+      if (EC_DEFAULTS_PREFIX != nil)
+        {
+          NSString      *str;
+
+          str = [NSString stringWithFormat: @"-%@Daemon", EC_DEFAULTS_PREFIX];
+          index = [args indexOfObject: str];
+        }
+      if (NSNotFound == index)
+        {
+          index = [args indexOfObject: @"-Daemon"];
+        }
+      if (NSNotFound != index)
+        {
+          [args replaceObjectAtIndex: index + 1 withObject: @"NO"];
+        }
+      else
+        {
           [args addObject: @"-Daemon"];
           [args addObject: @"NO"];
+        }
 
       /* Set args to tell task it is being watched.
        */

EcControl.m

@@ -2758,6 +2758,7 @@ static NSString*	cmdWord(NSArray* a, unsigned int pos)
       NSMutableDictionary	*root;
       NSEnumerator		*rootEnum;
       id			hostKey;
+      NSString                  *digest = nil;
 
       if ([conf isKindOfClass: [NSDictionary class]] == NO)
 	{
@@ -2775,6 +2776,50 @@ static NSString*	cmdWord(NSArray* a, unsigned int pos)
        * applications/classes levels of the configuration.
        */
       conf = [self recursiveInclude: conf];
+
+      /* Get the EcControlKey from the generic area of the configuration.
+       * If present, this should be an MD5 digest of the actual key.
+       */
+      if ([[conf objectForKey: @"*"] isKindOfClass: [NSDictionary class]]
+        && [[[conf objectForKey: @"*"] objectForKey: @"*"]
+          isKindOfClass: [NSDictionary class]])
+        {
+          digest = [[[conf objectForKey: @"*"] objectForKey: @"*"]
+            objectForKey: @"EcControlKey"];
+        }
+      if ([controlKey length] > 0 && nil == digest)
+        {
+          ASSIGN(configFailed,
+            @"EcControlKey supplied on startup but not in Control.plist");
+          [[self cmdLogFile: logname] printf: @"%@", configFailed];
+          return NO;
+        }
+      if ([controlKey length] == 0 && digest != nil)
+        {
+          ASSIGN(configFailed,
+            @"EcControlKey configured but no value supplied on startup");
+          [[self cmdLogFile: logname] printf: @"%@", configFailed];
+          return NO;
+        }
+      if (digest != nil)
+        {
+          NSData        *key;
+          NSData        *md5;
+          NSString      *hex;
+
+          key = [[NSData alloc] initWithHexadecimalRepresentation: controlKey];
+          md5 = [key md5Digest];
+          RELEASE(key);
+          hex = [md5 hexadecimalRepresentation];
+          if (NO == [digest isEqual: hex])
+            {
+              ASSIGN(configFailed,
+                @"EcControlKey is not the MD5 digest of value from startup");
+              [[self cmdLogFile: logname] printf: @"%@", configFailed];
+              return NO;
+            }
+        }
+
       [conf writeToFile: @"/tmp/Control.cnf" atomically: YES];
       [mgr changeFileAttributes: [NSDictionary dictionaryWithObjectsAndKeys:
         [NSNumber numberWithInt: 0666], NSFilePosixPermissions,

EcProcess.h

@@ -182,6 +182,7 @@ typedef enum    {
  *	Useful functions -
  */
 extern void		cmdSetHome(NSString *home);
+extern NSString*	cmdDataDir();
 extern NSString*	cmdLogsDir(NSString *date);
 extern NSString*	cmdLogKey(EcLogType t);
 extern NSString*	cmdLogName();
@@ -408,6 +409,23 @@ extern NSString*	cmdVersion(NSString *ver);
 */
 @interface EcProcess : NSObject <CmdClient,EcAlarmDestination>
 
+/** This method is provided to prompt for an encryptionkey using the
+ * specified key name and read in a value from the terminal.<br />
+ * The entered value must be an even numbered sequence of hexadecimal
+ * digits, each pair representing one byte of the key.<br />
+ * The key length (number of bytes) must be the specified size, a value
+ * between 16 and 128, which is exactly half the number of hexadecimal
+ * digits that must be entered.<br />
+ * If the digest is not supplied, the user will be required to
+ * enter the value twice (and the two values must match) for
+ * confirmation.<br />
+ * If the digest is supplied, the md5 digest of the entered key must
+ * match it (but the user does not need to enter the value twice).
+ */
++ (NSString*) ecGetKey: (const char*)name
+                  size: (unsigned)size
+                   md5: (NSData*)digest;
+
 /** Provides initial configuration.
  * This method is used by -init and its return value is passed to
  * -initWithDefaults: method.<br />

config.h.in

@@ -94,6 +94,9 @@
 /* Define to 1 if you have <sys/wait.h> that is POSIX.1 compatible. */
 #undef HAVE_SYS_WAIT_H
 
+/* Define to 1 if you have the <termios.h> header file. */
+#undef HAVE_TERMIOS_H
+
 /* Define to 1 if you have the <unistd.h> header file. */
 #undef HAVE_UNISTD_H
 

configure

@@ -3581,7 +3581,7 @@ fi
 done
 
 
-for ac_header in arpa/inet.h arpa/telnet.h netinet/in.h netdb.h pwd.h string.h fcntl.h sys/fcntl.h sys/file.h sys/resource.h sys/time.h sys/types.h sys/socket.h sys/signal.h stdlib.h unistd.h
+for ac_header in arpa/inet.h arpa/telnet.h netinet/in.h netdb.h pwd.h string.h fcntl.h sys/fcntl.h sys/file.h sys/resource.h sys/time.h sys/types.h sys/socket.h sys/signal.h stdlib.h unistd.h termios.h
 do :
   as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"

configure.ac

@@ -35,7 +35,7 @@ AC_TYPE_SIGNAL
 AC_HEADER_STDC
 AC_HEADER_TIME
 AC_HEADER_SYS_WAIT
-AC_CHECK_HEADERS(arpa/inet.h arpa/telnet.h netinet/in.h netdb.h pwd.h string.h fcntl.h sys/fcntl.h sys/file.h sys/resource.h sys/time.h sys/types.h sys/socket.h sys/signal.h stdlib.h unistd.h)
+AC_CHECK_HEADERS(arpa/inet.h arpa/telnet.h netinet/in.h netdb.h pwd.h string.h fcntl.h sys/fcntl.h sys/file.h sys/resource.h sys/time.h sys/types.h sys/socket.h sys/signal.h stdlib.h unistd.h termios.h)
 
 AC_TYPE_GETGROUPS
 AC_TYPE_SIGNAL