[RFC PATCH 1/5] ima: extend clone() with IMA namespace support

[Mehmet Kayaalp]

From: Yuqiong Sun <suny@xxxxxxxxxx>

Add new CONFIG_IMA_NS config option.  Let clone() create a new IMA
namespace upon CLONE_NEWNS flag. Add ima_ns data structure in nsproxy.
ima_ns is allocated and freed upon IMA namespace creation and exit.
Currently, the ima_ns contains no useful IMA data but only a dummy
interface. This patch creates the framework for namespacing the different
aspects of IMA (eg. IMA-audit, IMA-measurement, IMA-appraisal).

Signed-off-by: Yuqiong Sun <suny@xxxxxxxxxx>

Changelog:
* Use CLONE_NEWNS instead of a new CLONE_NEWIMA flag
* Use existing ima.h headers
* Move the ima_namespace.c to security/integrity/ima/ima_ns.c
* Fix typo INFO->INO
* Each namespace free's itself, removed recursively free'ing
until init_ima_ns from free_ima_ns()

Signed-off-by: Mehmet Kayaalp <mkayaalp@xxxxxxxxxxxxxxxxxx>
---
 fs/proc/namespaces.c              |   3 +
 include/linux/ima.h               |  37 ++++++++
 include/linux/nsproxy.h           |   1 +
 include/linux/proc_ns.h           |   2 +
 init/Kconfig                      |   8 ++
 kernel/nsproxy.c                  |  15 ++++
 security/integrity/ima/Makefile   |   1 +
 security/integrity/ima/ima.h      |   9 ++
 security/integrity/ima/ima_init.c |   4 +
 security/integrity/ima/ima_ns.c   | 183 ++++++++++++++++++++++++++++++++++++++
 10 files changed, 263 insertions(+)
 create mode 100644 security/integrity/ima/ima_ns.c

diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 3803b24..222a64e 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -32,6 +32,9 @@ static const struct proc_ns_operations *ns_entries[] = {
 #ifdef CONFIG_CGROUPS
 	&cgroupns_operations,
 #endif
+#ifdef CONFIG_IMA_NS
+	&imans_operations,
+#endif
 };
 
 static const char *proc_ns_get_link(struct dentry *dentry,
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 0e4647e..11e4841 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -105,4 +105,41 @@ static inline int ima_inode_removexattr(struct dentry *dentry,
 	return 0;
 }
 #endif /* CONFIG_IMA_APPRAISE */
+
+struct ima_namespace {
+	struct kref kref;
+	struct user_namespace *user_ns;
+	struct ns_common ns;
+	struct ima_namespace *parent;
+};
+
+extern struct ima_namespace init_ima_ns;
+
+#ifdef CONFIG_IMA_NS
+void put_ima_ns(struct ima_namespace *ns);
+struct ima_namespace *copy_ima(unsigned long flags,
+			       struct user_namespace *user_ns,
+			       struct ima_namespace *old_ns);
+static inline struct ima_namespace *get_current_ns(void)
+{
+	return current->nsproxy->ima_ns;
+}
+#else
+static inline void put_ima_ns(struct ima_namespace *ns)
+{
+	return;
+}
+
+static inline struct ima_namespace *copy_ima(unsigned long flags,
+					     struct user_namespace *user_ns,
+					     struct ima_namespace *old_ns)
+{
+	return old_ns;
+}
+
+static inline struct ima_namespace *get_current_ns(void)
+{
+	return NULL;
+}
+#endif /* CONFIG_IMA_NS */
 #endif /* _LINUX_IMA_H */
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index ac0d65b..a97031d 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -35,6 +35,7 @@ struct nsproxy {
 	struct pid_namespace *pid_ns_for_children;
 	struct net 	     *net_ns;
 	struct cgroup_namespace *cgroup_ns;
+	struct ima_namespace *ima_ns;
 };
 extern struct nsproxy init_nsproxy;
 
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index 58ab28d..c7c1239 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -31,6 +31,7 @@ extern const struct proc_ns_operations pidns_for_children_operations;
 extern const struct proc_ns_operations userns_operations;
 extern const struct proc_ns_operations mntns_operations;
 extern const struct proc_ns_operations cgroupns_operations;
+extern const struct proc_ns_operations imans_operations;
 
 /*
  * We always define these enumerators
@@ -42,6 +43,7 @@ enum {
 	PROC_USER_INIT_INO	= 0xEFFFFFFDU,
 	PROC_PID_INIT_INO	= 0xEFFFFFFCU,
 	PROC_CGROUP_INIT_INO	= 0xEFFFFFFBU,
+	PROC_IMA_INIT_INO	= 0xEFFFFFFAU,
 };
 
 #ifdef CONFIG_PROC_FS
diff --git a/init/Kconfig b/init/Kconfig
index 1d3475f..339f84d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1287,6 +1287,14 @@ config NET_NS
 	help
 	  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 mount namespace.
+	  Namespaced IMA data enables having IMA features work separately
+	  for each mount namespace.
 
 endif # NAMESPACES
 
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index f6c5d33..85be341 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -27,6 +27,7 @@
 #include <linux/syscalls.h>
 #include <linux/cgroup.h>
 #include <linux/perf_event.h>
+#include <linux/ima.h>
 
 static struct kmem_cache *nsproxy_cachep;
 
@@ -44,6 +45,9 @@ struct nsproxy init_nsproxy = {
 #ifdef CONFIG_CGROUPS
 	.cgroup_ns		= &init_cgroup_ns,
 #endif
+#ifdef CONFIG_IMA_NS
+	.ima_ns                 = &init_ima_ns,
+#endif
 };
 
 static inline struct nsproxy *create_nsproxy(void)
@@ -110,8 +114,17 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
 		goto out_net;
 	}
 
+	new_nsp->ima_ns = copy_ima(flags, user_ns, tsk->nsproxy->ima_ns);
+	if (IS_ERR(new_nsp->ima_ns)) {
+		err = PTR_ERR(new_nsp->ima_ns);
+		goto out_ima;
+	}
+
 	return new_nsp;
 
+out_ima:
+	if (new_nsp->ima_ns)
+		put_ima_ns(new_nsp->ima_ns);
 out_net:
 	put_cgroup_ns(new_nsp->cgroup_ns);
 out_cgroup:
@@ -181,6 +194,8 @@ void free_nsproxy(struct nsproxy *ns)
 	if (ns->pid_ns_for_children)
 		put_pid_ns(ns->pid_ns_for_children);
 	put_cgroup_ns(ns->cgroup_ns);
+	if (ns->ima_ns)
+		put_ima_ns(ns->ima_ns);
 	put_net(ns->net_ns);
 	kmem_cache_free(nsproxy_cachep, ns);
 }
diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
index 29f198b..20493f0 100644
--- a/security/integrity/ima/Makefile
+++ b/security/integrity/ima/Makefile
@@ -8,5 +8,6 @@ obj-$(CONFIG_IMA) += ima.o
 ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \
 	 ima_policy.o ima_template.o ima_template_lib.o
 ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o
+ima-$(CONFIG_IMA_NS) += ima_ns.o
 ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o
 obj-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index d52b487..8a8234a 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -291,6 +291,15 @@ static inline int ima_read_xattr(struct dentry *dentry,
 
 #endif /* CONFIG_IMA_APPRAISE */
 
+#ifdef CONFIG_IMA_NS
+int ima_ns_init(void);
+#else
+static inline int ima_ns_init(void)
+{
+	return 0;
+}
+#endif /* CONFIG_IMA_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 2967d49..7f884a7 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -137,5 +137,9 @@ int __init ima_init(void)
 
 	ima_init_policy();
 
+	rc = ima_ns_init();
+	if (rc != 0)
+		return rc;
+
 	return ima_fs_init();
 }
diff --git a/security/integrity/ima/ima_ns.c b/security/integrity/ima/ima_ns.c
new file mode 100644
index 0000000..383217b
--- /dev/null
+++ b/security/integrity/ima/ima_ns.c
@@ -0,0 +1,183 @@
+/*
+ * Copyright (C) 2008 IBM Corporation
+ * Author: Yuqiong Sun <suny@xxxxxxxxxx>
+ *
+ * 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/proc_ns.h>
+#include <linux/kref.h>
+#include <linux/slab.h>
+#include <linux/ima.h>
+
+#include "ima.h"
+
+static void get_ima_ns(struct ima_namespace *ns);
+
+int ima_init_namespace(struct ima_namespace *ns)
+{
+	return 0;
+}
+
+int ima_ns_init(void)
+{
+	return ima_init_namespace(&init_ima_ns);
+}
+
+static struct ima_namespace *create_ima_ns(void)
+{
+	struct ima_namespace *ima_ns;
+
+	ima_ns = kmalloc(sizeof(*ima_ns), GFP_KERNEL);
+	if (ima_ns)
+		kref_init(&ima_ns->kref);
+
+	return ima_ns;
+}
+
+/**
+ * Clone a new ns copying an original ima namespace, setting refcount to 1
+ *
+ * @old_ns: old ima namespace to clone
+ * @user_ns: user namespace that current task runs in
+ * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
+ */
+static struct ima_namespace *clone_ima_ns(struct user_namespace *user_ns,
+					  struct ima_namespace *old_ns)
+{
+	struct ima_namespace *ns;
+	int err;
+
+	ns = create_ima_ns();
+	if (!ns)
+		return ERR_PTR(-ENOMEM);
+
+	err = ns_alloc_inum(&ns->ns);
+	if (err) {
+		kfree(ns);
+		return ERR_PTR(err);
+	}
+
+	ns->ns.ops = &imans_operations;
+	get_ima_ns(old_ns);
+	ns->parent = old_ns;
+	ns->user_ns = get_user_ns(user_ns);
+
+	ima_init_namespace(ns);
+
+	return ns;
+}
+
+/**
+ * Copy task's ima namespace, or clone it if flags specifies CLONE_NEWNS.
+ *
+ * @flags: flags used in the clone syscall
+ * @user_ns: user namespace that current task runs in
+ * @old_ns: old ima namespace to clone
+ */
+
+struct ima_namespace *copy_ima(unsigned long flags,
+			       struct user_namespace *user_ns,
+			       struct ima_namespace *old_ns)
+{
+	struct ima_namespace *new_ns;
+
+	BUG_ON(!old_ns);
+	get_ima_ns(old_ns);
+
+	if (!(flags & CLONE_NEWNS))
+		return old_ns;
+
+	new_ns = clone_ima_ns(user_ns, old_ns);
+	put_ima_ns(old_ns);
+
+	return new_ns;
+}
+
+static void destroy_ima_ns(struct ima_namespace *ns)
+{
+	put_user_ns(ns->user_ns);
+	ns_free_inum(&ns->ns);
+	kfree(ns);
+}
+
+static void free_ima_ns(struct kref *kref)
+{
+	struct ima_namespace *ns;
+
+	ns = container_of(kref, struct ima_namespace, kref);
+	destroy_ima_ns(ns);
+}
+
+static void get_ima_ns(struct ima_namespace *ns)
+{
+	kref_get(&ns->kref);
+}
+
+void put_ima_ns(struct ima_namespace *ns)
+{
+	kref_put(&ns->kref, free_ima_ns);
+}
+
+static inline struct ima_namespace *to_ima_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct ima_namespace, ns);
+}
+
+static struct ns_common *imans_get(struct task_struct *task)
+{
+	struct ima_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->ima_ns;
+		get_ima_ns(ns);
+	}
+	task_unlock(task);
+
+	return ns ? &ns->ns : NULL;
+}
+
+static void imans_put(struct ns_common *ns)
+{
+	put_ima_ns(to_ima_ns(ns));
+}
+
+static int imans_install(struct nsproxy *nsproxy, struct ns_common *new)
+{
+	struct ima_namespace *ns = to_ima_ns(new);
+
+	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+		return -EPERM;
+
+	get_ima_ns(ns);
+	put_ima_ns(nsproxy->ima_ns);
+	nsproxy->ima_ns = ns;
+	return 0;
+}
+
+const struct proc_ns_operations imans_operations = {
+	.name = "ima",
+	.type = CLONE_NEWNS,
+	.get = imans_get,
+	.put = imans_put,
+	.install = imans_install,
+};
+
+struct ima_namespace init_ima_ns = {
+	.kref = KREF_INIT(2),
+	.user_ns = &init_user_ns,
+	.ns.inum = PROC_IMA_INIT_INO,
+#ifdef CONFIG_IMA_NS
+	.ns.ops = &imans_operations,
+#endif
+	.parent = NULL,
+};
+EXPORT_SYMBOL(init_ima_ns);
-- 
2.9.4