[PATCH v12 16/26] ima: Add functions for creating and freeing of an ima_namespace

Stefan Berger
2022-04-20T14:07:06Z

Implement create_ima_ns() to create an empty ima_namespace. Defer its
initialization to a later point outside this function. Implement
free_ima_ns() to free it.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>

---
v9:
- Set user_ns->ims_ns = NULL in free_ima_ns()
- Refactored create_ima_ns() to defer initialization
- Removed pr_debug functions
---
include/linux/ima.h | 13 ++++++
security/integrity/ima/Makefile | 1 +
security/integrity/ima/ima.h | 15 +++++++
security/integrity/ima/ima_init_ima_ns.c | 2 +-
security/integrity/ima/ima_ns.c | 53 ++++++++++++++++++++++++
5 files changed, 83 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 fcb60a44e05f..76d19995ab89 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -220,4 +220,17 @@ 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 054b8f67be04..3e77738aec2c 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -171,6 +171,7 @@ 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,
@@ -506,4 +507,18 @@ static inline struct ima_namespace
return NULL;
}

+#ifdef CONFIG_IMA_NS
+
+struct ima_namespace *create_ima_ns(void);
+
+#else
+
+static inline struct ima_namespace *create_ima_ns(void)
+{
+ 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 c4fe8f3e9a73..b497062090cf 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)
{
int ret;

diff --git a/security/integrity/ima/ima_ns.c b/security/integrity/ima/ima_ns.c
new file mode 100644
index 000000000000..b3b81a1e313e
--- /dev/null
+++ b/security/integrity/ima/ima_ns.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016-2021 IBM Corporation
+ * Author:
+ * Yuqiong Sun <suny@us.ibm.com>
+ * Stefan Berger <stefanb@linux.vnet.ibm.com>
+ */
+
+#include <linux/ima.h>
+
+#include "ima.h"
+
+static struct kmem_cache *imans_cachep;
+
+struct ima_namespace *create_ima_ns(void)
+{
+ struct ima_namespace *ns;
+
+ ns = kmem_cache_zalloc(imans_cachep, GFP_KERNEL);
+ if (!ns)
+ return ERR_PTR(-ENOMEM);
+
+ return ns;
+}
+
+/* destroy_ima_ns() must only be called after ima_init_namespace() was called */
+static void destroy_ima_ns(struct ima_namespace *ns)
+{
+ unregister_blocking_lsm_notifier(&ns->ima_lsm_policy_notifier);
+ kfree(ns->arch_policy_entry);
+ ima_free_policy_rules(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);
+
+ kmem_cache_free(imans_cachep, ns);
+
+ user_ns->ima_ns = NULL;
+}
+
+static int __init imans_cache_init(void)
+{
+ imans_cachep = KMEM_CACHE(ima_namespace, SLAB_PANIC);
+ return 0;
+}
+subsys_initcall(imans_cache_init)
--
2.34.1