[PATCH 5.15 197/297] ima: annotate iint mutex to avoid lockdep false positive warnings

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Amir Goldstein <amir73il@xxxxxxxxx>

commit e044374a8a0a99e46f4e6d6751d3042b6d9cc12e upstream.

It is not clear that IMA should be nested at all, but as long is it
measures files both on overlayfs and on underlying fs, we need to
annotate the iint mutex to avoid lockdep false positives related to
IMA + overlayfs, same as overlayfs annotates the inode mutex.

Reported-and-tested-by: syzbot+b42fe626038981fb7bfa@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 security/integrity/iint.c |   48 +++++++++++++++++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 11 deletions(-)

--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -66,9 +66,32 @@ struct integrity_iint_cache *integrity_i
 	return iint;
 }
 
-static void iint_free(struct integrity_iint_cache *iint)
+#define IMA_MAX_NESTING (FILESYSTEM_MAX_STACK_DEPTH+1)
+
+/*
+ * It is not clear that IMA should be nested at all, but as long is it measures
+ * files both on overlayfs and on underlying fs, we need to annotate the iint
+ * mutex to avoid lockdep false positives related to IMA + overlayfs.
+ * See ovl_lockdep_annotate_inode_mutex_key() for more details.
+ */
+static inline void iint_lockdep_annotate(struct integrity_iint_cache *iint,
+					 struct inode *inode)
+{
+#ifdef CONFIG_LOCKDEP
+	static struct lock_class_key iint_mutex_key[IMA_MAX_NESTING];
+
+	int depth = inode->i_sb->s_stack_depth;
+
+	if (WARN_ON_ONCE(depth < 0 || depth >= IMA_MAX_NESTING))
+		depth = 0;
+
+	lockdep_set_class(&iint->mutex, &iint_mutex_key[depth]);
+#endif
+}
+
+static void iint_init_always(struct integrity_iint_cache *iint,
+			     struct inode *inode)
 {
-	kfree(iint->ima_hash);
 	iint->ima_hash = NULL;
 	iint->version = 0;
 	iint->flags = 0UL;
@@ -80,6 +103,14 @@ static void iint_free(struct integrity_i
 	iint->ima_creds_status = INTEGRITY_UNKNOWN;
 	iint->evm_status = INTEGRITY_UNKNOWN;
 	iint->measured_pcrs = 0;
+	mutex_init(&iint->mutex);
+	iint_lockdep_annotate(iint, inode);
+}
+
+static void iint_free(struct integrity_iint_cache *iint)
+{
+	kfree(iint->ima_hash);
+	mutex_destroy(&iint->mutex);
 	kmem_cache_free(iint_cache, iint);
 }
 
@@ -112,6 +143,8 @@ struct integrity_iint_cache *integrity_i
 	if (!iint)
 		return NULL;
 
+	iint_init_always(iint, inode);
+
 	write_lock(&integrity_iint_lock);
 
 	p = &integrity_iint_tree.rb_node;
@@ -161,25 +194,18 @@ void integrity_inode_free(struct inode *
 	iint_free(iint);
 }
 
-static void init_once(void *foo)
+static void iint_init_once(void *foo)
 {
 	struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo;
 
 	memset(iint, 0, sizeof(*iint));
-	iint->ima_file_status = INTEGRITY_UNKNOWN;
-	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
-	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
-	iint->ima_read_status = INTEGRITY_UNKNOWN;
-	iint->ima_creds_status = INTEGRITY_UNKNOWN;
-	iint->evm_status = INTEGRITY_UNKNOWN;
-	mutex_init(&iint->mutex);
 }
 
 static int __init integrity_iintcache_init(void)
 {
 	iint_cache =
 	    kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
-			      0, SLAB_PANIC, init_once);
+			      0, SLAB_PANIC, iint_init_once);
 	return 0;
 }
 DEFINE_LSM(integrity) = {