[patch] Patch to clean passwords

secure-pwman.patch (text/plain), 2.88 KB, created by chris-gentoo on 2004-10-11 02:16:51 UTC

diff -ur smbpwman-0.5/smbpwman.c smbpwman-0.5.comment/smbpwman.c
--- smbpwman-0.5.orig/smbpwman.c	2002-05-02 11:44:30.000000000 +1000
+++ smbpwman-0.5/smbpwman.c	2004-08-20 00:40:41.000000000 +1000
@@ -38,6 +38,13 @@
  *
  *
  * all str commands are 0x00 terminated string of chars.
+ *
+ * Patched by Chris Jensen - 19 Aug 2004
+ *   Clear passwords after first use
+ *   Overwrite passwords with 0x00 before freeing memory
+ *   Overwrite and free all passwords on server shutdown
+ *   Add --verbose option to prevent disconnection from terminal
+ *	and print debugging
  */
 
 #include "version.h"
@@ -52,6 +59,21 @@
 	char *value;
 } *root = 0;
 
+/* clean_free_str
+   Whipes a string to all 0 before freeing it
+   Used to ensure passwords are not left in memory
+*/
+void clean_free_str(char **ptr)
+{
+	if (*ptr)
+	{
+		memset(*ptr, 0x00, strlen(*ptr));
+		free(*ptr);
+	}
+
+	*ptr = NULL;
+}
+
 int cache_store_entry(char *key, char *value)
 {
 	// search from root to the end of the list...
@@ -63,7 +85,8 @@
 		if(strcmp((*entry)->key, key) == 0)
 		{
 			//printf("Already an entry for key %s\n", key);
-			free((*entry)->value);
+			clean_free_str(&((*entry)->value));
+			
 			(*entry)->value = strdup(value);
 			return 1;
 		}
@@ -80,16 +103,39 @@
 	return 0;
 }
 
+/* scrub_memory
+   Write 0x00 over all passwords stored in memory before shutting down
+*/
+void scrub_memory(void)
+{
+	struct entry_t *entry = root;
+	
+	while (entry)
+	{
+		clean_free_str(&(entry->key));
+		clean_free_str(&(entry->value));
+
+		entry = entry->next;
+	}
+}
+
 char *cache_retrieve_entry(char *key)
 {
 	struct entry_t *entry = root;
+	char *password = NULL;
 
 	while(entry)
 	{
 		//printf("%s, %s\n", entry->key, entry->value);
 		if(strcmp(key, entry->key) == 0)
 		{
-			return entry->value;
+			if (entry->value)
+			{
+				password = strdup(entry->value);
+				
+				clean_free_str(&(entry->value));
+			}
+			return password;
 		}
 		entry = entry->next;
 	}
@@ -158,22 +204,35 @@
 		return 1;
 	}
 
+	if ((argc > 1) && (((strcmp(argv[1], "--verbose") == 0) ||
+			(strcmp(argv[1], "-v") == 0))))
+	{
+		verbose = 1;
+	}
-	// detach process...
-	cpid=fork();
 
-	if(cpid != 0)
+	if (!verbose)
 	{
-		exit(0);
+		// detach process...
+		cpid=fork();
+	
+		if(cpid != 0)
+		{
+			exit(0);
+		}
+		setsid();
+		chdir("/");
 	}
-	setsid();
-	chdir("/");
 
 	fprintf(lock, "%d\n", getpid());
+
 	fclose(lock);
-	close(0);
-	close(1);
-	close(2);
 
+	if (!verbose)
+	{
+		close(0);
+		close(1);
+		close(2);
+	}
 
 	log(LOG_INFO, "smbpwman daemon version %s ready\n", VERSION);
 	while(1)
@@ -241,6 +300,7 @@
 					result = 0x00;
 					write(cs, &result, sizeof(result));
 					write(cs, password, strlen(password) + 1);
+					clean_free_str(&password);
 				}
 				else
 				{
@@ -255,6 +315,7 @@
 					printf("SHUTDOWN\n");
 				}
 				log(LOG_INFO, "shutdown request.  daemon terminating\n");
+				scrub_memory();
 				return 0;
 				break;