Re: [PATCH v7 01/14] ima: Add IMA namespace support

From: Stefan Berger <stefanb@linux.ibm.com>

Implement an IMA namespace data structure that gets created alongside a
user namespace with CLONE_NEWUSER. This lays down the foundation for
namespacing the different aspects of IMA (eg. IMA-audit, IMA-measurement,
IMA-appraisal).

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Suggested-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
 include/linux/ima.h                      | 33 ++++++++++++
 include/linux/user_namespace.h           |  4 ++
 init/Kconfig                             | 10 ++++
 kernel/user.c                            |  7 +++
 kernel/user_namespace.c                  |  8 +++
 security/integrity/ima/Makefile          |  3 +-
 security/integrity/ima/ima.h             |  8 +++
 security/integrity/ima/ima_init.c        |  4 ++
 security/integrity/ima/ima_init_ima_ns.c | 28 ++++++++++
 security/integrity/ima/ima_ns.c          | 65 ++++++++++++++++++++++++
 10 files changed, 169 insertions(+), 1 deletion(-)
 create mode 100644 security/integrity/ima/ima_init_ima_ns.c
 create mode 100644 security/integrity/ima/ima_ns.c

diff --git a/include/linux/ima.h b/include/linux/ima.h
index b6ab66a546ae..61461ee5b208 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h

@@ -11,6 +11,7 @@
 #include <linux/fs.h>
 #include <linux/security.h>
 #include <linux/kexec.h>
+#include <linux/user_namespace.h>
 #include <crypto/hash_info.h>
 struct linux_binprm;
 

@@ -210,6 +211,38 @@ static inline int ima_inode_removexattr(struct dentry *dentry,
 }
 #endif /* CONFIG_IMA_APPRAISE */
 
+extern struct ima_namespace init_ima_ns;
+
+#ifdef CONFIG_IMA_NS
+
+void free_ima_ns(struct user_namespace *ns);
+int create_ima_ns(struct user_namespace *user_ns);
+
+static inline struct ima_namespace *get_current_ns(void)
+{
+	return current_user_ns()->ima_ns;
+}
+
+#else
+
+static inline void free_ima_ns(struct user_namespace *user_ns)
+{
+}
+
+static inline int create_ima_ns(struct user_namespace *user_ns)
+{
+#ifdef CONFIG_IMA
+	user_ns->ima_ns = &init_ima_ns;
+#endif
+	return 0;
+}
+
+static inline struct ima_namespace *get_current_ns(void)
+{
+	return &init_ima_ns;
+}
+#endif /* CONFIG_IMA_NS */
+
 #if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
 extern bool ima_appraise_signature(enum kernel_read_file_id func);
 #else

diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 33a4240e6a6f..5249db04d62b 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h

@@ -36,6 +36,7 @@ struct uid_gid_map { /* 64 bytes -- 1 cache line */
 #define USERNS_INIT_FLAGS USERNS_SETGROUPS_ALLOWED
 
 struct ucounts;
+struct ima_namespace;
 
 enum ucount_type {
 	UCOUNT_USER_NAMESPACES,

@@ -99,6 +100,9 @@ struct user_namespace {
 #endif
 	struct ucounts		*ucounts;
 	long ucount_max[UCOUNT_COUNTS];
+#ifdef CONFIG_IMA
+	struct ima_namespace	*ima_ns;
+#endif
 } __randomize_layout;
 
 struct ucounts {

diff --git a/init/Kconfig b/init/Kconfig
index 11f8a845f259..27890607e8cb 100644
--- a/init/Kconfig
+++ b/init/Kconfig

@@ -1242,6 +1242,16 @@ config NET_NS
 	  Allow user space to create what appear to be multiple instances
 	  of the network stack.
 
+config IMA_NS
+	bool "IMA namespace"
+	depends on USER_NS
+	depends on IMA
+	default y
+	help
+	  Allow the creation of IMA namespaces for each user namespace.
+	  Namespaced IMA enables having IMA features work separately
+	  in each IMA namespace.
+
 endif # NAMESPACES
 
 config CHECKPOINT_RESTORE

diff --git a/kernel/user.c b/kernel/user.c
index e2cf8c22b539..287751d89b44 100644
--- a/kernel/user.c
+++ b/kernel/user.c

@@ -20,6 +20,10 @@
 #include <linux/user_namespace.h>
 #include <linux/proc_ns.h>
 
+#ifdef CONFIG_IMA
+extern struct ima_namespace init_ima_ns;
+#endif
+
 /*
  * userns count is 1 for root user, 1 for init_uts_ns,
  * and 1 for... ?

@@ -67,6 +71,9 @@ struct user_namespace init_user_ns = {
 	.keyring_name_list = LIST_HEAD_INIT(init_user_ns.keyring_name_list),
 	.keyring_sem = __RWSEM_INITIALIZER(init_user_ns.keyring_sem),
 #endif
+#ifdef CONFIG_IMA
+	.ima_ns = &init_ima_ns,
+#endif
 };
 EXPORT_SYMBOL_GPL(init_user_ns);
 

diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 6b2e3ca7ee99..6fa01323aac9 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c

@@ -20,6 +20,7 @@
 #include <linux/fs_struct.h>
 #include <linux/bsearch.h>
 #include <linux/sort.h>
+#include <linux/ima.h>
 
 static struct kmem_cache *user_ns_cachep __read_mostly;
 static DEFINE_MUTEX(userns_state_mutex);

@@ -141,8 +142,14 @@ int create_user_ns(struct cred *new)
 	if (!setup_userns_sysctls(ns))
 		goto fail_keyring;
 
+	ret = create_ima_ns(ns);