[S390] Add debug_register_mode() function to debug feature API

The new function supports setting of permissions for the debugfs files
created by the debug feature. In addition to that, the function provides
uid and gid as parameters for future use. Currently only root is allowed
for uid and gid.
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

Documentation/s390/s390dbf.txt

@@ -115,6 +115,27 @@ Return Value: Handle for generated debug area
 Description:  Allocates memory for a debug log     
               Must not be called within an interrupt handler 
 
+----------------------------------------------------------------------------
+debug_info_t *debug_register_mode(char *name, int pages, int nr_areas,
+				  int buf_size, mode_t mode, uid_t uid,
+				  gid_t gid);
+
+Parameter:    name:	   Name of debug log (e.g. used for debugfs entry)
+	      pages:	   Number of pages, which will be allocated per area
+	      nr_areas:    Number of debug areas
+	      buf_size:    Size of data area in each debug entry
+	      mode:	   File mode for debugfs files. E.g. S_IRWXUGO
+	      uid:	   User ID for debugfs files. Currently only 0 is
+			   supported.
+	      gid:	   Group ID for debugfs files. Currently only 0 is
+			   supported.
+
+Return Value: Handle for generated debug area
+	      NULL if register failed
+
+Description:  Allocates memory for a debug log
+	      Must not be called within an interrupt handler
+
 ---------------------------------------------------------------------------
 void debug_unregister (debug_info_t * id);
 

arch/s390/kernel/debug.c

@@ -73,7 +73,7 @@ static ssize_t debug_input(struct file *file, const char __user *user_buf,
 static int debug_open(struct inode *inode, struct file *file);
 static int debug_close(struct inode *inode, struct file *file);
 static debug_info_t*  debug_info_create(char *name, int pages_per_area,
-			int nr_areas, int buf_size);
+			int nr_areas, int buf_size, mode_t mode);
 static void debug_info_get(debug_info_t *);
 static void debug_info_put(debug_info_t *);
 static int debug_prolog_level_fn(debug_info_t * id,
@@ -327,7 +327,8 @@ debug_info_free(debug_info_t* db_info){
  */
 
 static debug_info_t*
-debug_info_create(char *name, int pages_per_area, int nr_areas, int buf_size)
+debug_info_create(char *name, int pages_per_area, int nr_areas, int buf_size,
+		  mode_t mode)
 {
 	debug_info_t* rc;
 
@@ -336,6 +337,8 @@ debug_info_create(char *name, int pages_per_area, int nr_areas, int buf_size)
         if(!rc) 
 		goto out;
 
+	rc->mode = mode & ~S_IFMT;
+
 	/* create root directory */
         rc->debugfs_root_entry = debugfs_create_dir(rc->name,
 					debug_debugfs_root_entry);
@@ -676,23 +679,30 @@ debug_close(struct inode *inode, struct file *file)
 }
 
 /*
- * debug_register:
- * - creates and initializes debug area for the caller
- * - returns handle for debug area
+ * debug_register_mode:
+ * - Creates and initializes debug area for the caller
+ *   The mode parameter allows to specify access rights for the s390dbf files
+ * - Returns handle for debug area
  */
 
-debug_info_t*
-debug_register (char *name, int pages_per_area, int nr_areas, int buf_size)
+debug_info_t *debug_register_mode(char *name, int pages_per_area, int nr_areas,
+				  int buf_size, mode_t mode, uid_t uid,
+				  gid_t gid)
 {
 	debug_info_t *rc = NULL;
 
+	/* Since debugfs currently does not support uid/gid other than root, */
+	/* we do not allow gid/uid != 0 until we get support for that. */
+	if ((uid != 0) || (gid != 0))
+		printk(KERN_WARNING "debug: Warning - Currently only uid/gid "
+		       "= 0 are supported. Using root as owner now!");
 	if (!initialized)
 		BUG();
 	mutex_lock(&debug_mutex);
 
         /* create new debug_info */
 
-	rc = debug_info_create(name, pages_per_area, nr_areas, buf_size);
+	rc = debug_info_create(name, pages_per_area, nr_areas, buf_size, mode);
 	if(!rc) 
 		goto out;
 	debug_register_view(rc, &debug_level_view);
@@ -705,6 +715,20 @@ out:
 	mutex_unlock(&debug_mutex);
 	return rc;
 }
+EXPORT_SYMBOL(debug_register_mode);
+
+/*
+ * debug_register:
+ * - creates and initializes debug area for the caller
+ * - returns handle for debug area
+ */
+
+debug_info_t *debug_register(char *name, int pages_per_area, int nr_areas,
+			     int buf_size)
+{
+	return debug_register_mode(name, pages_per_area, nr_areas, buf_size,
+				   S_IRUSR | S_IWUSR, 0, 0);
+}
 
 /*
  * debug_unregister:
@@ -1073,15 +1097,16 @@ debug_register_view(debug_info_t * id, struct debug_view *view)
 	int rc = 0;
 	int i;
 	unsigned long flags;
-	mode_t mode = S_IFREG;
+	mode_t mode;
 	struct dentry *pde;
 
 	if (!id)
 		goto out;
-	if (view->prolog_proc || view->format_proc || view->header_proc)
-		mode |= S_IRUSR;
-	if (view->input_proc)
-		mode |= S_IWUSR;
+	mode = (id->mode | S_IFREG) & ~S_IXUGO;
+	if (!(view->prolog_proc || view->format_proc || view->header_proc))
+		mode &= ~(S_IRUSR | S_IRGRP | S_IROTH);
+	if (!view->input_proc)
+		mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
 	pde = debugfs_create_file(view->name, mode, id->debugfs_root_entry,
 				id , &debug_file_ops);
 	if (!pde){

include/asm-s390/debug.h

@@ -73,6 +73,7 @@ typedef struct debug_info {
 	struct dentry* debugfs_entries[DEBUG_MAX_VIEWS];
 	struct debug_view* views[DEBUG_MAX_VIEWS];	
 	char name[DEBUG_MAX_NAME_LEN];
+	mode_t mode;
 } debug_info_t;
 
 typedef int (debug_header_proc_t) (debug_info_t* id,
@@ -122,6 +123,10 @@ debug_entry_t* debug_exception_common(debug_info_t* id, int level,
 debug_info_t* debug_register(char* name, int pages, int nr_areas,
                              int buf_size);
 
+debug_info_t *debug_register_mode(char *name, int pages, int nr_areas,
+				  int buf_size, mode_t mode, uid_t uid,
+				  gid_t gid);
+
 void debug_unregister(debug_info_t* id);
 
 void debug_set_level(debug_info_t* id, int new_level);