[PATCH v8 13/19] ima: Add functions for creation and freeing of an ima_namespace

[Stefan Berger]

From: Stefan Berger <stefanb@xxxxxxxxxxxxx>

Implement create_ima_ns() to create and initialize an ima_namespace
and implement free_ima_ns() to free it.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
---
 include/linux/ima.h                      | 13 +++++
 security/integrity/ima/Makefile          |  1 +
 security/integrity/ima/ima.h             | 16 +++++++
 security/integrity/ima/ima_init_ima_ns.c |  2 +-
 security/integrity/ima/ima_ns.c          | 61 ++++++++++++++++++++++++
 5 files changed, 92 insertions(+), 1 deletion(-)
 create mode 100644 security/integrity/ima/ima_ns.c

diff --git a/include/linux/ima.h b/include/linux/ima.h
index e1d65162d1fb..06c88cb17b21 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -226,4 +226,17 @@ static inline bool ima_appraise_signature(enum kernel_read_file_id func)
 	return false;
 }
 #endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */
+
+#ifdef CONFIG_IMA_NS
+
+void free_ima_ns(struct user_namespace *ns);
+
+#else
+
+static inline void free_ima_ns(struct user_namespace *user_ns)
+{
+}
+
+#endif /* CONFIG_IMA_NS */
+
 #endif /* _LINUX_IMA_H */
diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
index f8a5e5f3975d..b86a35fbed60 100644
--- a/security/integrity/ima/Makefile
+++ b/security/integrity/ima/Makefile
@@ -14,6 +14,7 @@ ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o
 ima-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o
 ima-$(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) += ima_asymmetric_keys.o
 ima-$(CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS) += ima_queue_keys.o
+ima-$(CONFIG_IMA_NS) += ima_ns.o
 
 ifeq ($(CONFIG_EFI),y)
 ima-$(CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT) += ima_efi.o
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index f63c6f22b853..4255301e5b96 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -163,6 +163,7 @@ extern bool ima_canonical_fmt;
 int ima_init(void);
 int ima_fs_init(void);
 int ima_ns_init(void);
+int ima_init_namespace(struct ima_namespace *ns);
 int ima_add_template_entry(struct ima_namespace *ns,
 			   struct ima_template_entry *entry, int violation,
 			   const char *op, struct inode *inode,
@@ -503,4 +504,19 @@ static inline struct ima_namespace *get_current_ns(void)
 	return &init_ima_ns;
 }
 
+#ifdef CONFIG_IMA_NS
+
+struct ima_namespace *create_ima_ns(struct user_namespace *user_ns);
+
+#else
+
+static inline struct ima_namespace *
+create_ima_ns(struct user_namespace *user_ns)
+{
+	WARN(1, "Cannot create an IMA namespace\n");
+	return ERR_PTR(-EFAULT);
+}
+
+#endif /* CONFIG_IMA_NS */
+
 #endif /* __LINUX_IMA_H */
diff --git a/security/integrity/ima/ima_init_ima_ns.c b/security/integrity/ima/ima_init_ima_ns.c
index 68671f976756..6eac998781c3 100644
--- a/security/integrity/ima/ima_init_ima_ns.c
+++ b/security/integrity/ima/ima_init_ima_ns.c
@@ -8,7 +8,7 @@
 
 #include "ima.h"
 
-static int ima_init_namespace(struct ima_namespace *ns)
+int ima_init_namespace(struct ima_namespace *ns)
 {
 	INIT_LIST_HEAD(&ns->ima_default_rules);
 	INIT_LIST_HEAD(&ns->ima_policy_rules);
diff --git a/security/integrity/ima/ima_ns.c b/security/integrity/ima/ima_ns.c
new file mode 100644
index 000000000000..675466d292e8
--- /dev/null
+++ b/security/integrity/ima/ima_ns.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016-2021 IBM Corporation
+ * Author:
+ *  Yuqiong Sun <suny@xxxxxxxxxx>
+ *  Stefan Berger <stefanb@xxxxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/ima.h>
+
+#include "ima.h"
+
+static struct kmem_cache *imans_cachep;
+
+struct ima_namespace *create_ima_ns(struct user_namespace *user_ns)
+{
+	struct ima_namespace *ns;
+	int err;
+
+	ns = kmem_cache_zalloc(imans_cachep, GFP_KERNEL);
+	if (!ns)
+		return ERR_PTR(-ENOMEM);
+	pr_debug("NEW     ima_ns: %p\n", ns);
+
+	err = ima_init_namespace(ns);
+	if (err)
+		goto fail_free;
+
+	user_ns->ima_ns = ns;
+
+	return ns;
+
+fail_free:
+	kmem_cache_free(imans_cachep, ns);
+
+	return ERR_PTR(err);
+}
+
+static void destroy_ima_ns(struct ima_namespace *ns)
+{
+	pr_debug("DESTROY ima_ns: %p\n", ns);
+	ima_free_policy_rules(ns);
+	kmem_cache_free(imans_cachep, ns);
+}
+
+void free_ima_ns(struct user_namespace *user_ns)
+{
+	struct ima_namespace *ns = user_ns->ima_ns;
+
+	if (!ns || WARN_ON(ns == &init_ima_ns))
+		return;
+
+	destroy_ima_ns(ns);
+}
+
+static int __init imans_cache_init(void)
+{
+	imans_cachep = KMEM_CACHE(ima_namespace, SLAB_PANIC);
+	return 0;
+}
+subsys_initcall(imans_cache_init)
-- 
2.31.1