From patchwork Sun Apr 18 07:57:31 2010
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Subject: Clean up open_cred_file()
Date: Sat, 17 Apr 2010 21:57:31 -0000
From: Scott Lovenberg <scott.lovenberg@gmail.com>
X-Patchwork-Id: 50390
Message-Id: <j2vb1fc6a561004180057y3b277826z87eac4e1cee01c02@mail.gmail.com>
To: linux-cifs-client@lists.samba.org

This patch cleans up the open_cred_file() function in mount.cifs.c.  It also
zeros out the password buffer.
I made the buffer length a static int since macro'ing it seemed like leaky
abstraction (it only makes sense within the scope of the function, IMHO).
Is this acceptable?

P.S. - I'm still getting used to git, please let me know if this patch is
formatted incorrectly.


diff --git a/mount.cifs.c b/mount.cifs.c
index 1aa3329..54feeaf 100644
--- a/mount.cifs.c
+++ b/mount.cifs.c
@@ -98,7 +98,7 @@
 #endif
 
 #define MOUNT_PASSWD_SIZE 128
-#define DOMAIN_SIZE 64
+#define MAX_DOMAIN_SIZE 64
 
 /*
  * value of the ver= option that gets passed to the kernel. Used to indicate
@@ -128,7 +128,7 @@ struct parsed_mount_info {
 	char share[MAX_SHARE_LEN + 1];
 	char prefix[PATH_MAX + 1];
 	char options[MAX_OPTIONS_LEN];
-	char domain[DOMAIN_SIZE + 1];
+	char domain[MAX_DOMAIN_SIZE + 1];
 	char username[MAX_USERNAME_SIZE + 1];
 	char password[MOUNT_PASSWD_SIZE + 1];
 	char addrlist[MAX_ADDR_LIST_LEN];
@@ -511,14 +511,26 @@ toggle_dac_capability(int writable, int enable)
 #endif /* HAVE_LIBCAP */
 #endif /* HAVE_LIBCAP_NG */
 
+/*
+ * Null terminates string at first '\n'.
+ */
+static void null_terminate_endl(char* source)
+{
+	char* newline = strchr(source, '\n');
+	if (newline)
+		*newline = '\0';
+}
+
 static int open_cred_file(char *file_name,
 			  struct parsed_mount_info *parsed_info)
 {
 	char *line_buf;
-	char *temp_val, *newline;
+	char *temp_val;
 	FILE *fs = NULL;
-	int i, length;
-
+	int i;
+	const int line_buf_size = 4096;
+	const int min_non_white = 10;
+	
 	i = toggle_dac_capability(0, 1);
 	if (i)
 		return i;
@@ -541,58 +553,54 @@ static int open_cred_file(char *file_name,
 		return i;
 	}
 
-	line_buf = (char *)malloc(4096);
+	line_buf = (char *)malloc(line_buf_size);
 	if (line_buf == NULL) {
 		fclose(fs);
 		return EX_SYSERR;
 	}
 
-	while (fgets(line_buf, 4096, fs)) {
-		/* parse line from credential file */
-
+	/* parse line from credential file*/
+	while (fgets(line_buf, line_buf_size, fs)) {
 		/* eat leading white space */
-		for (i = 0; i < 4086; i++) {
+		for (i = 0; i < line_buf_size - min_non_white + 1; i++) {
 			if ((line_buf[i] != ' ') && (line_buf[i] != '\t'))
 				break;
-			/* if whitespace - skip past it */
 		}
 
-		/* NULL terminate at newline */
-		newline = strchr(line_buf + i, '\n');
-		if (newline)
-			*newline = '\0';
-
+		/* parse user */
+		null_terminate_endl(line_buf);
 		if (strncasecmp("user", line_buf + i, 4) == 0) {
 			temp_val = strchr(line_buf + i, '=');
 			if (temp_val) {
 				/* go past equals sign */
 				temp_val++;
-				for (length = 0; length < 4087; length++) {
-					if ((temp_val[length] == '\n')
-					    || (temp_val[length] == '\0')) {
-						temp_val[length] = '\0';
-						break;
-					}
-				}
-				if (length > 4086) {
+				null_terminate_endl(temp_val);
+				if (strlen(temp_val) > MAX_USERNAME_SIZE) {
 					fprintf(stderr,
 						"mount.cifs failed due to malformed username in credentials file\n");
-					memset(line_buf, 0, 4096);
+					memset(line_buf, 0, line_buf_size);
 					return EX_USAGE;
 				}
-				parsed_info->got_user = 1;
-				strlcpy(parsed_info->username, temp_val,
-					sizeof(parsed_info->username));
+				parse_username(temp_val, parsed_info);
 			}
-		} else if (strncasecmp("pass", line_buf + i, 4) == 0) {
+		}
+		
+		/* parse password */ 
+		else if (strncasecmp("pass", line_buf + i, 4) == 0) {
 			temp_val = strchr(line_buf + i, '=');
 			if (!temp_val)
 				continue;
-			++temp_val;
+                        /* go past equals sign */
+			temp_val++;
 			i = set_password(parsed_info, temp_val);
+			/* zero out password from buffer */
+			memset(line_buf, 0, line_buf_size);
 			if (i)
 				return i;
-		} else if (strncasecmp("dom", line_buf + i, 3) == 0) {
+		}
+		
+		/* parse domain */ 
+		else if (strncasecmp("dom", line_buf + i, 3) == 0) {
 			temp_val = strchr(line_buf + i, '=');
 			if (temp_val) {
 				/* go past equals sign */
@@ -601,16 +609,8 @@ static int open_cred_file(char *file_name,
 					fprintf(stderr, "\nDomain %s\n",
 						temp_val);
 
-				for (length = 0; length < DOMAIN_SIZE + 1;
-				     length++) {
-					if ((temp_val[length] == '\n')
-					    || (temp_val[length] == '\0')) {
-						temp_val[length] = '\0';
-						break;
-					}
-				}
-
-				if (length > DOMAIN_SIZE) {
+				null_terminate_endl(temp_val);
+				if (strlen(temp_val) > MAX_DOMAIN_SIZE) {
 					fprintf(stderr,
 						"mount.cifs failed: domain in credentials file too long\n");
 					return EX_USAGE;
@@ -620,7 +620,6 @@ static int open_cred_file(char *file_name,
 					sizeof(parsed_info->domain));
 			}
 		}
-
 	}
 	fclose(fs);
 	SAFE_FREE(line_buf);