ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 157 insertions, 0 deletions

diff --git a/security/landlock/cred.h b/security/landlock/cred.h
new file mode 100644
index 000000000..a5ff99579
--- /dev/null
+++ b/security/landlock/cred.h
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock - Credential hooks
+ *
+ * Copyright © 2019-2020 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2019-2020 ANSSI
+ * Copyright © 2021-2025 Microsoft Corporation
+ */
+
+#ifndef _SECURITY_LANDLOCK_CRED_H
+#define _SECURITY_LANDLOCK_CRED_H
+
+#include <linux/container_of.h>
+#include <linux/cred.h>
+#include <linux/init.h>
+#include <linux/rcupdate.h>
+
+#include "access.h"
+#include "domain.h"
+#include "limits.h"
+#include "ruleset.h"
+#include "setup.h"
+
+/**
+ * struct landlock_cred_security - Credential security blob
+ *
+ * This structure is packed to minimize the size of struct
+ * landlock_file_security.  However, it is always aligned in the LSM cred blob,
+ * see lsm_set_blob_size().
+ *
+ * When updating this, also update landlock_cred_copy() if needed.
+ */
+struct landlock_cred_security {
+	/**
+	 * @domain: Immutable domain enforced on a task.
+	 */
+	struct landlock_domain *domain;
+
+#ifdef CONFIG_SECURITY_LANDLOCK_LOG
+	/**
+	 * @domain_exec: Bitmask identifying the domain layers that were enforced by
+	 * the current task's executed file (i.e. no new execve(2) since
+	 * landlock_restrict_self(2)).
+	 */
+	u16 domain_exec;
+	/**
+	 * @log_subdomains_off: Set if the domain descendants's log_status should be
+	 * set to %LANDLOCK_LOG_DISABLED.  This is not a landlock_hierarchy
+	 * configuration because it applies to future descendant domains and it does
+	 * not require a current domain.
+	 */
+	u8 log_subdomains_off : 1;
+#endif /* CONFIG_SECURITY_LANDLOCK_LOG */
+} __packed;
+
+#ifdef CONFIG_SECURITY_LANDLOCK_LOG
+
+/* Makes sure all layer executions can be stored. */
+static_assert(BITS_PER_TYPE(typeof_member(struct landlock_cred_security,
+					  domain_exec)) >=
+	      LANDLOCK_MAX_NUM_LAYERS);
+
+#endif /* CONFIG_SECURITY_LANDLOCK_LOG */
+
+static inline struct landlock_cred_security *
+landlock_cred(const struct cred *cred)
+{
+	return cred->security + landlock_blob_sizes.lbs_cred;
+}
+
+static inline void landlock_cred_copy(struct landlock_cred_security *dst,
+				      const struct landlock_cred_security *src)
+{
+	landlock_put_domain(dst->domain);
+
+	*dst = *src;
+
+	landlock_get_domain(src->domain);
+}
+
+static inline struct landlock_domain *landlock_get_current_domain(void)
+{
+	return landlock_cred(current_cred())->domain;
+}
+
+/* The call needs to come from an RCU read-side critical section. */
+static inline const struct landlock_domain *
+landlock_get_task_domain(const struct task_struct *const task)
+{
+	return landlock_cred(__task_cred(task))->domain;
+}
+
+static inline bool landlocked(const struct task_struct *const task)
+{
+	bool has_dom;
+
+	if (task == current)
+		return !!landlock_get_current_domain();
+
+	rcu_read_lock();
+	has_dom = !!landlock_get_task_domain(task);
+	rcu_read_unlock();
+	return has_dom;
+}
+
+/**
+ * landlock_get_applicable_subject - Return the subject's Landlock credential
+ *                                   if its enforced domain applies to (i.e.
+ *                                   handles) at least one of the access rights
+ *                                   specified in @masks
+ *
+ * @cred: credential
+ * @masks: access masks
+ * @handle_layer: returned youngest layer handling a subset of @masks.  Not set
+ *                if the function returns NULL.
+ *
+ * Return: landlock_cred(@cred) if any access rights specified in @masks is
+ * handled, or NULL otherwise.
+ */
+static inline const struct landlock_cred_security *
+landlock_get_applicable_subject(const struct cred *const cred,
+				const struct access_masks masks,
+				size_t *const handle_layer)
+{
+	const union access_masks_all masks_all = {
+		.masks = masks,
+	};
+	const struct landlock_domain *domain;
+	ssize_t layer_level;
+
+	if (!cred)
+		return NULL;
+
+	domain = landlock_cred(cred)->domain;
+	if (!domain)
+		return NULL;
+
+	for (layer_level = domain->num_layers - 1; layer_level >= 0;
+	     layer_level--) {
+		union access_masks_all layer = {
+			.masks = domain->handled_masks[layer_level],
+		};
+
+		if (layer.all & masks_all.all) {
+			if (handle_layer)
+				*handle_layer = layer_level;
+
+			return landlock_cred(cred);
+		}
+	}
+
+	return NULL;
+}
+
+__init void landlock_add_cred_hooks(void);
+
+#endif /* _SECURITY_LANDLOCK_CRED_H */