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, 118 insertions, 0 deletions

diff --git a/drivers/md/dm-ima.h b/drivers/md/dm-ima.h
new file mode 100644
index 000000000..0ec013d15
--- /dev/null
+++ b/drivers/md/dm-ima.h
@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Microsoft Corporation
+ *
+ * Author: Tushar Sugandhi <tusharsu@linux.microsoft.com>
+ *
+ * Header file for device mapper IMA measurements.
+ */
+
+#ifndef DM_IMA_H
+#define DM_IMA_H
+
+#define DM_IMA_MEASUREMENT_BUF_LEN	4096
+#define DM_IMA_DEVICE_BUF_LEN		1024
+#define DM_IMA_TARGET_METADATA_BUF_LEN	128
+#define DM_IMA_TARGET_DATA_BUF_LEN	2048
+#define DM_IMA_DEVICE_CAPACITY_BUF_LEN	128
+
+#define __dm_ima_stringify(s) #s
+#define __dm_ima_str(s) __dm_ima_stringify(s)
+
+#define DM_IMA_VERSION_STR "dm_version="	\
+	__dm_ima_str(DM_VERSION_MAJOR) "."	\
+	__dm_ima_str(DM_VERSION_MINOR) "."	\
+	__dm_ima_str(DM_VERSION_PATCHLEVEL) ";"
+
+enum dm_ima_table_op {
+	DM_IMA_TABLE_SAVE,
+	DM_IMA_TABLE_RESTORE,
+};
+
+#ifdef CONFIG_IMA
+
+struct dm_ima_device_table_metadata {
+	/*
+	 * Contains data specific to the device which is common across
+	 * all the targets in the table (e.g. name, uuid, major, minor, etc).
+	 * The values are stored in comma separated list of key1=val1,key2=val2;
+	 * pairs delimited by a semicolon at the end of the list.
+	 */
+	char *device_metadata;
+	unsigned int device_metadata_len;
+	unsigned int num_targets;
+	sector_t capacity;
+
+	/*
+	 * Contains the sha256 hashes of the IMA measurements of the target
+	 * attributes' key-value pairs from the active/inactive tables.
+	 */
+	char *hash;
+	unsigned int hash_len;
+};
+
+struct dm_ima_context {
+	struct dm_ima_device_table_metadata table;
+	unsigned int update_idx;
+	char dev_name[DM_NAME_LEN*2];
+	char dev_uuid[DM_UUID_LEN*2];
+};
+
+/*
+ * This structure contains device metadata, and table hash for
+ * active and inactive tables for ima measurements.
+ */
+struct dm_ima_measurements {
+	unsigned int update_idx;
+	unsigned int measure_idx;
+	struct wait_queue_head ima_wq;
+	spinlock_t ima_lock;
+	struct dm_ima_device_table_metadata active_table;
+	struct dm_ima_device_table_metadata inactive_table;
+};
+
+void dm_ima_init(struct mapped_device *md);
+void dm_ima_alloc_context(struct dm_ima_context **context, bool noio);
+void dm_ima_free_context(struct dm_ima_context *context);
+void dm_ima_context_table_op(struct mapped_device *md,
+			     struct dm_ima_context *context,
+			     enum dm_ima_table_op op);
+void dm_ima_measure_on_table_load(struct dm_table *table,
+				  struct dm_ima_context *context);
+void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap,
+				     struct dm_ima_context *context);
+void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all,
+				     struct dm_ima_context *context,
+				     unsigned int idx);
+void dm_ima_measure_on_table_clear(struct mapped_device *md,
+				   struct dm_ima_context *context);
+void dm_ima_measure_on_device_rename(struct mapped_device *md,
+				     struct dm_ima_context *context);
+
+#else
+
+struct dm_ima_context;
+
+static inline void dm_ima_init(struct mapped_device *md) {}
+static inline void dm_ima_alloc_context(struct dm_ima_context **context, bool noio) {}
+static inline void dm_ima_free_context(struct dm_ima_context *context) {}
+static inline void dm_ima_context_table_op(struct mapped_device *md,
+					   struct dm_ima_context *context,
+					   enum dm_ima_table_op op) {}
+static inline void dm_ima_measure_on_table_load(struct dm_table *table,
+						struct dm_ima_context *context) {}
+static inline void dm_ima_measure_on_device_resume(struct mapped_device *md,
+						   bool swap,
+						   struct dm_ima_context *context) {}
+static inline void dm_ima_measure_on_device_remove(struct mapped_device *md,
+						   bool remove_all,
+						   struct dm_ima_context *context,
+						   unsigned int idx) {}
+static inline void dm_ima_measure_on_table_clear(struct mapped_device *md,
+						 struct dm_ima_context *context) {}
+static inline void dm_ima_measure_on_device_rename(struct mapped_device *md,
+						   struct dm_ima_context *context) {}
+
+#endif /* CONFIG_IMA */
+
+#endif /* DM_IMA_H */