linux-kernel - [PATCH v2 06/28] module: Use RCU in find_module

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20241220174731.514432-7-bigeasy@linutronix.de>
Date: Fri, 20 Dec 2024 18:41:20 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-modules@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Daniel Gomez <da.gomez@...sung.com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Petr Pavlu <petr.pavlu@...e.com>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Jiri Kosina <jikos@...nel.org>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Petr Mladek <pmladek@...e.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	linux-trace-kernel@...r.kernel.org,
	live-patching@...r.kernel.org
Subject: [PATCH v2 06/28] module: Use RCU in find_module_all().

The modules list and module::kallsyms can be accessed under RCU
assumption.

Remove module_assert_mutex_or_preempt() from find_module_all() so it can
be used under RCU protection without warnings. Update its callers to use
RCU protection instead of preempt_disable().

Cc: Jiri Kosina <jikos@...nel.org>
Cc: Joe Lawrence <joe.lawrence@...hat.com>
Cc: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Miroslav Benes <mbenes@...e.cz>
Cc: Petr Mladek <pmladek@...e.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-trace-kernel@...r.kernel.org
Cc: live-patching@...r.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 include/linux/module.h      | 2 +-
 kernel/livepatch/core.c     | 4 +---
 kernel/module/kallsyms.c    | 1 +
 kernel/module/main.c        | 6 ++----
 kernel/trace/trace_kprobe.c | 9 +++------
 5 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 94acbacdcdf18..5c1f7ea76c8cb 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -663,7 +663,7 @@ static inline bool within_module(unsigned long addr, const struct module *mod)
 	return within_module_init(addr, mod) || within_module_core(addr, mod);
 }
 
-/* Search for module by name: must be in a RCU-sched critical section. */
+/* Search for module by name: must be in a RCU critical section. */
 struct module *find_module(const char *name);
 
 extern void __noreturn __module_put_and_kthread_exit(struct module *mod,
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 3c21c31796db0..f8932c63b08e3 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -59,7 +59,7 @@ static void klp_find_object_module(struct klp_object *obj)
 	if (!klp_is_module(obj))
 		return;
 
-	rcu_read_lock_sched();
+	guard(rcu)();
 	/*
 	 * We do not want to block removal of patched modules and therefore
 	 * we do not take a reference here. The patches are removed by
@@ -75,8 +75,6 @@ static void klp_find_object_module(struct klp_object *obj)
 	 */
 	if (mod && mod->klp_alive)
 		obj->mod = mod;
-
-	rcu_read_unlock_sched();
 }
 
 static bool klp_initialized(void)
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 4eef518204eb5..3cba9f933b24f 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -450,6 +450,7 @@ unsigned long module_kallsyms_lookup_name(const char *name)
 	unsigned long ret;
 
 	/* Don't lock: we're in enough trouble already. */
+	guard(rcu)();
 	preempt_disable();
 	ret = __module_kallsyms_lookup_name(name);
 	preempt_enable();
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 5cce4a92d7ba3..5aa56ec8e203e 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -374,16 +374,14 @@ bool find_symbol(struct find_symbol_arg *fsa)
 }
 
 /*
- * Search for module by name: must hold module_mutex (or preempt disabled
- * for read-only access).
+ * Search for module by name: must hold module_mutex (or RCU for read-only
+ * access).
  */
 struct module *find_module_all(const char *name, size_t len,
 			       bool even_unformed)
 {
 	struct module *mod;
 
-	module_assert_mutex_or_preempt();
-
 	list_for_each_entry_rcu(mod, &modules, list,
 				lockdep_is_held(&module_mutex)) {
 		if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 263fac44d3ca3..c7db326f4e88e 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -123,9 +123,8 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 	if (!p)
 		return true;
 	*p = '\0';
-	rcu_read_lock_sched();
-	ret = !!find_module(tk->symbol);
-	rcu_read_unlock_sched();
+	scoped_guard(rcu)
+		ret = !!find_module(tk->symbol);
 	*p = ':';
 
 	return ret;
@@ -800,12 +799,10 @@ static struct module *try_module_get_by_name(const char *name)
 {
 	struct module *mod;
 
-	rcu_read_lock_sched();
+	guard(rcu)();
 	mod = find_module(name);
 	if (mod && !try_module_get(mod))
 		mod = NULL;
-	rcu_read_unlock_sched();
-
 	return mod;
 }
 #else
-- 
2.45.2