Commit a4a2a427 authored by Jim Cromie's avatar Jim Cromie Committed by Greg Kroah-Hartman
Browse files

dyndbg: validate class FOO by checking with module 



Add module-to-class validation:

  #> echo class DRM_UT_KMS +p > /proc/dynamic_debug/control

If a query has "class FOO", then ddebug_find_valid_class(), called
from ddebug_change(), requires that FOO is known to module X,
otherwize the query is skipped entirely for X.  This protects each
module's class-space, other than the default:31.

The authors' choice of FOO is highly selective, giving isolation
and/or coordinated sharing of FOOs.  For example, only DRM modules
should know and respond to DRM_UT_KMS.

So this, combined with module's opt-in declaration of known classes,
effectively privatizes the .class_id space for each module (or
coordinated set of modules).

Notes:

For all "class FOO" queries, ddebug_find_valid_class() is called, it
returns the map matching the query, and sets valid_class via an
*outvar).

If no "class FOO" is supplied, valid_class = _CLASS_DFLT.  This
insures that legacy queries do not trample on new class'd callsites,
as they get added.

Also add a new column to control-file output, displaying non-default
class-name (when found) or the "unknown _id:", if it has not been
(correctly) declared with one of the declarator macros.

Signed-off-by: default avatarJim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-18-jim.cromie@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c45f67ac

lib/dynamic_debug.c

+68 −8
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ struct ddebug_query { 
	const char *module;

	const char *function;

	const char *format;

	const char *class_string;

	unsigned int first_lineno, last_lineno;

};
@@ -136,15 +137,33 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg) 
			fmtlen--;

	}



	v3pr_info("%s: func=\"%s\" file=\"%s\" module=\"%s\" format=\"%.*s\" lineno=%u-%u\n",

	v3pr_info("%s: func=\"%s\" file=\"%s\" module=\"%s\" format=\"%.*s\" lineno=%u-%u class=%s\n",

		  msg,

		  query->function ?: "",

		  query->filename ?: "",

		  query->module ?: "",

		  fmtlen, query->format ?: "",

		 query->first_lineno, query->last_lineno);

		  query->first_lineno, query->last_lineno, query->class_string);

}



static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table const *dt,

							  const char *class_string, int *class_id)

{

	struct ddebug_class_map *map;

	int idx;



	list_for_each_entry(map, &dt->maps, link) {

		idx = match_string(map->class_names, map->length, class_string);

		if (idx >= 0) {

			*class_id = idx + map->base;

			return map;

		}

	}

	*class_id = -ENOENT;

	return NULL;

}



#define __outvar /* filled by callee */

/*

 * Search the tables for _ddebug's which match the given `query' and

 * apply the `flags' and `mask' to them.  Returns number of matching
@@ -159,6 +178,8 @@ static int ddebug_change(const struct ddebug_query *query, 
	unsigned int newflags;

	unsigned int nfound = 0;

	struct flagsbuf fbuf, nbuf;

	struct ddebug_class_map *map = NULL;

	int __outvar valid_class;



	/* search for matching ddebugs */

	mutex_lock(&ddebug_lock);
@@ -169,9 +190,22 @@ static int ddebug_change(const struct ddebug_query *query, 
		    !match_wildcard(query->module, dt->mod_name))

			continue;



		if (query->class_string) {

			map = ddebug_find_valid_class(dt, query->class_string, &valid_class);

			if (!map)

				continue;

		} else {

			/* constrain query, do not touch class'd callsites */

			valid_class = _DPRINTK_CLASS_DFLT;

		}



		for (i = 0; i < dt->num_ddebugs; i++) {

			struct _ddebug *dp = &dt->ddebugs[i];



			/* match site against query-class */

			if (dp->class_id != valid_class)

				continue;



			/* match against the source filename */

			if (query->filename &&

			    !match_wildcard(query->filename, dp->filename) &&
@@ -420,6 +454,8 @@ static int ddebug_parse_query(char *words[], int nwords, 
		} else if (!strcmp(keyword, "line")) {

			if (parse_linerange(query, arg))

				return -EINVAL;

		} else if (!strcmp(keyword, "class")) {

			rc = check_set(&query->class_string, arg, "class");

		} else {

			pr_err("unknown keyword \"%s\"\n", keyword);

			return -EINVAL;
@@ -854,6 +890,20 @@ static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos) 
	return dp;

}



#define class_in_range(class_id, map)					\

	(class_id >= map->base && class_id < map->base + map->length)



static const char *ddebug_class_name(struct ddebug_iter *iter, struct _ddebug *dp)

{

	struct ddebug_class_map *map;



	list_for_each_entry(map, &iter->table->maps, link)

		if (class_in_range(dp->class_id, map))

			return map->class_names[dp->class_id - map->base];



	return NULL;

}



/*

 * Seq_ops show method.  Called several times within a read()

 * call from userspace, with ddebug_lock held.  Formats the
@@ -865,6 +915,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p) 
	struct ddebug_iter *iter = m->private;

	struct _ddebug *dp = p;

	struct flagsbuf flags;

	char const *class;



	if (p == SEQ_START_TOKEN) {

		seq_puts(m,
@@ -877,7 +928,16 @@ static int ddebug_proc_show(struct seq_file *m, void *p) 
		   iter->table->mod_name, dp->function,

		   ddebug_describe_flags(dp->flags, &flags));

	seq_escape_str(m, dp->format, ESCAPE_SPACE, "\t\r\n\"");

	seq_puts(m, "\"\n");

	seq_puts(m, "\"");



	if (dp->class_id != _DPRINTK_CLASS_DFLT) {

		class = ddebug_class_name(iter, dp);

		if (class)

			seq_printf(m, " class:%s", class);

		else

			seq_printf(m, " class unknown, _id:%d", dp->class_id);

	}

	seq_puts(m, "\n");



	return 0;

}