[RFC 01/20] ima: Add IMA namespace support

[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                      | 59 +++++++++++++++++
 include/linux/user_namespace.h           |  4 ++
 init/Kconfig                             |  9 +++
 kernel/user.c                            |  9 ++-
 kernel/user_namespace.c                  | 16 +++++
 security/integrity/ima/Makefile          |  3 +-
 security/integrity/ima/ima.h             |  4 ++
 security/integrity/ima/ima_init.c        |  4 ++
 security/integrity/ima/ima_init_ima_ns.c | 32 +++++++++
 security/integrity/ima/ima_ns.c          | 82 ++++++++++++++++++++++++
 10 files changed, 220 insertions(+), 2 deletions(-)
 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..86d126b9ff2f 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 +211,64 @@ static inline int ima_inode_removexattr(struct dentry *dentry,
 }
 #endif /* CONFIG_IMA_APPRAISE */
 
+struct ima_namespace {
+	struct kref kref;
+	struct user_namespace *user_ns;
+};
+
+extern struct ima_namespace init_ima_ns;
+
+#ifdef CONFIG_IMA_NS
+
+void free_ima_ns(struct kref *kref);
+
+static inline struct ima_namespace *get_ima_ns(struct ima_namespace *ns)
+{
+	if (ns)
+		kref_get(&ns->kref);
+
+	return ns;
+}
+
+static inline void put_ima_ns(struct ima_namespace *ns)
+{
+	if (ns) {
+		pr_debug("DEREF   ima_ns: 0x%p  ctr: %d\n", ns, kref_read(&ns->kref));
+		kref_put(&ns->kref, free_ima_ns);
+	}
+}
+
+struct ima_namespace *copy_ima_ns(struct ima_namespace *old_ns,
+				  struct user_namespace *user_ns);
+
+static inline struct ima_namespace *get_current_ns(void)
+{
+	return current_user_ns()->ima_ns;
+}
+
+#else
+
+static inline struct ima_namespace *get_ima_ns(struct ima_namespace *ns)
+{
+	return ns;
+}
+
+static inline void put_ima_ns(struct ima_namespace *ns)
+{
+}
+
+static inline struct ima_namespace *copy_ima_ns(struct ima_namespace *old_ns,
+						struct user_namespace *user_ns)
+{
+	return old_ns;
+}
+
+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..598baf451a54 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1242,6 +1242,15 @@ 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 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..b5dc803a033d 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... ?
@@ -55,7 +59,7 @@ struct user_namespace init_user_ns = {
 			},
 		},
 	},
-	.ns.count = REFCOUNT_INIT(3),
+	.ns.count = REFCOUNT_INIT(4),
 	.owner = GLOBAL_ROOT_UID,
 	.group = GLOBAL_ROOT_GID,
 	.ns.inum = PROC_USER_INIT_INO,
@@ -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..c26885343b19 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 +142,20 @@ int create_user_ns(struct cred *new)
 	if (!setup_userns_sysctls(ns))
 		goto fail_keyring;
 
+#if CONFIG_IMA
+	ns->ima_ns = copy_ima_ns(parent_ns->ima_ns, ns);
+	if (IS_ERR(ns->ima_ns)) {
+		ret = PTR_ERR(ns->ima_ns);
+		goto fail_userns_sysctls;
+	}
+#endif
+
 	set_cred_user_ns(new, ns);
 	return 0;
+#if CONFIG_IMA
+fail_userns_sysctls:
+	retire_userns_sysctls(ns);
+#endif
 fail_keyring:
 #ifdef CONFIG_PERSISTENT_KEYRINGS
 	key_put(ns->persistent_keyring_register);
@@ -196,6 +209,9 @@ static void free_user_ns(struct work_struct *work)
 			kfree(ns->projid_map.forward);
 			kfree(ns->projid_map.reverse);
 		}
+#ifdef CONFIG_IMA
+		put_ima_ns(ns->ima_ns);
+#endif
 		retire_userns_sysctls(ns);
 		key_free_user_ns(ns);
 		ns_free_inum(&ns->ns);
diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
index 2499f2485c04..b86a35fbed60 100644
--- a/security/integrity/ima/Makefile
+++ b/security/integrity/ima/Makefile
@@ -7,13 +7,14 @@
 obj-$(CONFIG_IMA) += ima.o
 
 ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \
-	 ima_policy.o ima_template.o ima_template_lib.o
+	 ima_policy.o ima_template.o ima_template_lib.o ima_init_ima_ns.o
 ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o
 ima-$(CONFIG_IMA_APPRAISE_MODSIG) += ima_modsig.o
 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 be965a8715e4..2f8adf383054 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -418,6 +418,10 @@ static inline void ima_free_modsig(struct modsig *modsig)
 }
 #endif /* CONFIG_IMA_APPRAISE_MODSIG */
 
+int ima_ns_init(void);
+struct ima_namespace;
+int ima_init_namespace(struct ima_namespace *ns);
+
 /* LSM based policy rules require audit */
 #ifdef CONFIG_IMA_LSM_RULES
 
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index b26fa67476b4..f6ae4557a0da 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -120,6 +120,10 @@ int __init ima_init(void)
 {
 	int rc;
 
+	rc = ima_ns_init();
+	if (rc)
+		return rc;
+
 	ima_tpm_chip = tpm_default_chip();
 	if (!ima_tpm_chip)
 		pr_info("No TPM chip found, activating TPM-bypass!\n");
diff --git a/security/integrity/ima/ima_init_ima_ns.c b/security/integrity/ima/ima_init_ima_ns.c
new file mode 100644
index 000000000000..12723d77fe17
--- /dev/null
+++ b/security/integrity/ima/ima_init_ima_ns.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016-2018 IBM Corporation
+ * Author:
+ *   Yuqiong Sun <suny@us.ibm.com>
+ *   Stefan Berger <stefanb@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ */
+
+#include <linux/export.h>
+#include <linux/user_namespace.h>
+#include <linux/ima.h>
+#include <linux/proc_ns.h>
+
+int ima_init_namespace(struct ima_namespace *ns)
+{
+	return 0;
+}
+
+int __init ima_ns_init(void)
+{
+	return ima_init_namespace(&init_ima_ns);
+}
+
+struct ima_namespace init_ima_ns = {
+	.kref = KREF_INIT(1),
+	.user_ns = &init_user_ns,
+};
+EXPORT_SYMBOL(init_ima_ns);
diff --git a/security/integrity/ima/ima_ns.c b/security/integrity/ima/ima_ns.c
new file mode 100644
index 000000000000..fa8069acc217
--- /dev/null
+++ b/security/integrity/ima/ima_ns.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016-2018 IBM Corporation
+ * Author:
+ *  Yuqiong Sun <suny@us.ibm.com>
+ *  Stefan Berger <stefanb@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ */
+
+#include <linux/kref.h>
+#include <linux/slab.h>
+#include <linux/ima.h>
+#include <linux/mount.h>
+#include <linux/proc_ns.h>
+#include <linux/lsm_hooks.h>
+
+#include "ima.h"
+
+static struct kmem_cache *imans_cachep;
+
+static 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: 0x%p\n", ns);
+
+	kref_init(&ns->kref);
+	ns->user_ns = user_ns;
+
+	err = ima_init_namespace(ns);
+	if (err)
+		goto fail_free;
+
+	return ns;
+
+fail_free:
+	kmem_cache_free(imans_cachep, ns);
+
+	return ERR_PTR(err);
+}
+
+/**
+ * Copy an ima namespace - create a new one
+ *
+ * @old_ns: old ima namespace to clone
+ * @user_ns: User namespace
+ */
+struct ima_namespace *copy_ima_ns(struct ima_namespace *old_ns,
+				  struct user_namespace *user_ns)
+{
+	return create_ima_ns(user_ns);
+}
+
+static void destroy_ima_ns(struct ima_namespace *ns)
+{
+	pr_debug("DESTROY ima_ns: 0x%p\n", ns);
+	kmem_cache_free(imans_cachep, ns);
+}
+
+void free_ima_ns(struct kref *kref)
+{
+	struct ima_namespace *ns;
+
+	ns = container_of(kref, struct ima_namespace, kref);
+	BUG_ON(ns == &init_ima_ns);
+
+	destroy_ima_ns(ns);
+}
+
+int __init imans_cache_init(void)
+{
+	imans_cachep = KMEM_CACHE(ima_namespace, SLAB_PANIC);
+	return 0;
+}
+subsys_initcall(imans_cache_init)
-- 
2.31.1