[RFC PATCH v4 1/5] ima: Add IMA namespace support

From: Stefan Berger
Date: Fri May 11 2018 - 10:43:28 EST

From: Yuqiong Sun <suny@xxxxxxxxxx>

Add a new CONFIG_IMA_NS config option that enables one to create a new IMA
namespace. We do this by writing a file into IMA's new securityfs 'unshare'
file, which will have a new child process get the IMA namespace. We create
the IMA namespace when a user writes a boolean '1' into this file and
we cache the IMA namespace on the task_struct and take it from there upon
the next clone().

Currently, the iam_ns contains no useful IMA data but only a dummy inter-
face. This patch creates the framework for namespacing the different as-
pects of IMA (eg. IMA-audit, IMA-measurement, IMA-appraisal).

At this point one can create and activate a new IMA namespace by writing
a '1' into IMA's unshare file and subsequently creating a new process.
The 'ls -l' shows that the IMA namespace inode number temporarily changes
while the new IMA namespace is active after it was set up.

ls -l /proc/self/ns/ima
echo 1 > /sys/kernel/security/ima/unshare
ls -l /proc/self/ns/ima
ls -l /proc/self/ns/ima

Changelog:
v4:
* Use IMA's securityfs to spawn a new namespace using unshare file

v3:
* Use CLONE_NEWUSER instead of CLONE_NEWNS flag

v2:
* Moved ima_init_ns and related functions into own file that is
always compiled; init_ima_ns will always be there
* Fixed putting of imans->parent
* Move IMA namespace creation from nsproxy into mount namespace
code; get rid of procfs operations for IMA namespace

v1:
* 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: Yuqiong Sun <suny@xxxxxxxxxx>
Signed-off-by: Mehmet Kayaalp <mkayaalp@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxxxxxxx>
---
fs/proc/namespaces.c | 3 +
include/linux/ima.h | 50 ++++++++++
include/linux/nsproxy.h | 2 +
include/linux/proc_ns.h | 1 +
include/linux/sched.h | 6 ++
include/linux/user_namespace.h | 1 +
init/Kconfig | 8 ++
kernel/fork.c | 5 +
kernel/nsproxy.c | 25 ++++-
kernel/ucount.c | 1 +
security/integrity/ima/Makefile | 3 +-
security/integrity/ima/ima.h | 32 ++++++
security/integrity/ima/ima_fs.c | 55 +++++++++++
security/integrity/ima/ima_init.c | 4 +
security/integrity/ima/ima_init_ima_ns.c | 40 ++++++++
security/integrity/ima/ima_ns.c | 162 +++++++++++++++++++++++++++++++
16 files changed, 396 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/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 59b17e509f46..cc5e8e217412 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -33,6 +33,9 @@ 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 0e4647e0eb60..27a332cd0438 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -105,4 +105,54 @@ 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 ucounts *ucounts;
+ struct ns_common ns;
+ struct ima_namespace *parent;
+};
+
+extern struct ima_namespace init_ima_ns;
+
+#ifdef CONFIG_IMA_NS
+
+struct ima_namespace *copy_ima_ns(bool copy, struct user_namespace *user_ns,
+ struct ima_namespace *old_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)
+ kref_put(&ns->kref, free_ima_ns);
+}
+
+#else
+
+static inline struct ima_namespace *copy_ima_ns(bool copy,
+ struct user_namespace *user_ns,
+ struct ima_namespace *old_ns)
+{
+ return old_ns;
+}
+
+static inline struct ima_namespace *get_ima_ns(struct ima_namespace *ns)
+{
+ return ns;
+}
+
+static inline void put_ima_ns(struct ima_namespace *ns)
+{
+}
+
+#endif /* CONFIG_IMA_NS */
#endif /* _LINUX_IMA_H */
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 2ae1b1a4d84d..9d49f0a0cc97 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -10,6 +10,7 @@ struct uts_namespace;
struct ipc_namespace;
struct pid_namespace;
struct cgroup_namespace;
+struct ima_namespace;
struct fs_struct;

/*
@@ -36,6 +37,7 @@ 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 d31cb6215905..5be4411ecccc 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -32,6 +32,7 @@ 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
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b161ef8a902e..8a1f1b60959d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -53,6 +53,7 @@ struct sighand_struct;
struct signal_struct;
struct task_delay_info;
struct task_group;
+struct ima_namespace;

/*
* Task state bitmask. NOTE! These bits are also
@@ -1100,6 +1101,11 @@ struct task_struct {
void *security;
#endif

+#ifdef CONFIG_IMA_NS
+ /* child process will spawn a new IMA namespace */
+ bool ima_ns_for_child;
+#endif
+
/*
* New fields for task_struct should be added above here, so that
* they are included in the randomized portion of task_struct.
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index d6b74b91096b..d6def79eb0d1 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -49,6 +49,7 @@ enum ucount_type {
UCOUNT_INOTIFY_INSTANCES,
UCOUNT_INOTIFY_WATCHES,
#endif
+ UCOUNT_IMA_NAMESPACES,
UCOUNT_COUNTS,
};

diff --git a/init/Kconfig b/init/Kconfig
index e37f4b2a6445..2ae532aa12a0 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -932,6 +932,14 @@ 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 n
+ help
+ Allow the creation of IMA namespaces. Namespaced IMA data
+ enables having IMA features work separately in each IMA namespace.
+
endif # NAMESPACES

config SCHED_AUTOGROUP
diff --git a/kernel/fork.c b/kernel/fork.c
index e5d9d405ae4e..a0715ccf897e 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -91,6 +91,7 @@
#include <linux/kcov.h>
#include <linux/livepatch.h>
#include <linux/thread_info.h>
+#include <linux/ima.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -834,6 +835,10 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
tsk->fail_nth = 0;
#endif

+#ifdef CONFIG_IMA_NS
+ orig->ima_ns_for_child = false;
+#endif
+
return tsk;

free_stack:
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index f6c5d330059a..495f4a561d2a 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)
@@ -67,6 +71,7 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
{
struct nsproxy *new_nsp;
int err;
+ bool copy_ima = false;

new_nsp = create_nsproxy();
if (!new_nsp)
@@ -110,8 +115,21 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
goto out_net;
}

+#ifdef CONFIG_IMA_NS
+ copy_ima = tsk->ima_ns_for_child;
+ tsk->ima_ns_for_child = false;
+#endif
+ new_nsp->ima_ns = copy_ima_ns(copy_ima, 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:
+ put_net(new_nsp->net_ns);
out_net:
put_cgroup_ns(new_nsp->cgroup_ns);
out_cgroup:
@@ -143,7 +161,11 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)

if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
CLONE_NEWPID | CLONE_NEWNET |
- CLONE_NEWCGROUP)))) {
+ CLONE_NEWCGROUP)))
+#ifdef CONFIG_IMA_NS
+ && likely(!tsk->ima_ns_for_child)
+#endif
+ ) {
get_nsproxy(old_ns);
return 0;
}
@@ -182,6 +204,7 @@ void free_nsproxy(struct nsproxy *ns)
put_pid_ns(ns->pid_ns_for_children);
put_cgroup_ns(ns->cgroup_ns);
put_net(ns->net_ns);
+ put_ima_ns(ns->ima_ns);
kmem_cache_free(nsproxy_cachep, ns);
}

diff --git a/kernel/ucount.c b/kernel/ucount.c
index b4eeee03934f..bdd02e2e36cf 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -79,6 +79,7 @@ static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_inotify_instances"),
UCOUNT_ENTRY("max_inotify_watches"),
#endif
+ UCOUNT_ENTRY("max_ima_namespaces"),
{ }
};
#endif /* CONFIG_SYSCTL */
diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
index d921dc4f9eb0..cc60f726e651 100644
--- a/security/integrity/ima/Makefile
+++ b/security/integrity/ima/Makefile
@@ -7,7 +7,8 @@
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_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 d52b487ad259..f999328e5b49 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -24,6 +24,7 @@
#include <linux/hash.h>
#include <linux/tpm.h>
#include <linux/audit.h>
+#include <linux/ima.h>
#include <crypto/hash_info.h>

#include "../integrity.h"
@@ -291,6 +292,10 @@ static inline int ima_read_xattr(struct dentry *dentry,

#endif /* CONFIG_IMA_APPRAISE */

+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

@@ -313,6 +318,33 @@ static inline int security_filter_rule_match(u32 secid, u32 field, u32 op,
}
#endif /* CONFIG_IMA_LSM_RULES */

+static inline struct ima_namespace *to_ima_ns(struct ns_common *ns)
+{
+ return container_of(ns, struct ima_namespace, ns);
+}
+
+#ifdef CONFIG_IMA_NS
+
+extern const struct proc_ns_operations imans_operations;
+
+struct ima_namespace *copy_ima(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 struct ima_namespace *get_current_ns(void)
+{
+ return &init_ima_ns;
+}
+
+#endif /* CONFIG_IMA_NS */
+
#ifdef CONFIG_IMA_READ_POLICY
#define POLICY_FILE_FLAGS (S_IWUSR | S_IRUSR)
#else
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index fa540c0469da..9ebf97e29344 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -361,6 +361,9 @@ static struct dentry *ascii_runtime_measurements;
static struct dentry *runtime_measurements_count;
static struct dentry *violations;
static struct dentry *ima_policy;
+#ifdef CONFIG_IMA_NS
+static struct dentry *unshare;
+#endif

enum ima_fs_flags {
IMA_FS_BUSY,
@@ -446,6 +449,47 @@ static const struct file_operations ima_measure_policy_ops = {
.llseek = generic_file_llseek,
};

+#ifdef CONFIG_IMA_NS
+static int ima_open_unshare(struct inode *inode, struct file *filp)
+{
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ return 0;
+}
+
+static ssize_t ima_write_unshare(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ ssize_t length;
+ char *page;
+ bool set;
+
+ if (count >= PAGE_SIZE)
+ return -ENOMEM;
+
+ page = memdup_user_nul(buf, count);
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+
+ length = -EINVAL;
+ if (kstrtobool(page, &set))
+ goto out;
+
+ current->ima_ns_for_child = set;
+
+ length = count;
+out:
+ kfree(page);
+
+ return length;
+}
+
+static const struct file_operations ima_unshare_ops = {
+ .open = ima_open_unshare,
+ .write = ima_write_unshare,
+};
+#endif
+
int __init ima_fs_init(void)
{
ima_dir = securityfs_create_dir("ima", NULL);
@@ -485,6 +529,14 @@ int __init ima_fs_init(void)
if (IS_ERR(ima_policy))
goto out;

+#ifdef CONFIG_IMA_NS
+ unshare = securityfs_create_file("unshare", 0200,
+ ima_dir, NULL,
+ &ima_unshare_ops);
+ if (IS_ERR(unshare))
+ goto out;
+#endif
+
return 0;
out:
securityfs_remove(violations);
@@ -493,5 +545,8 @@ int __init ima_fs_init(void)
securityfs_remove(binary_runtime_measurements);
securityfs_remove(ima_dir);
securityfs_remove(ima_policy);
+#ifdef CONFIG_IMA_NS
+ securityfs_remove(unshare);
+#endif
return -1;
}
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index 29b72cd2502e..091e5fdee5fc 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_init_ima_ns.c b/security/integrity/ima/ima_init_ima_ns.c
new file mode 100644
index 000000000000..0bd6c418b8e3
--- /dev/null
+++ b/security/integrity/ima/ima_init_ima_ns.c
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2016-2018 IBM Corporation
+ * Author:
+ * Yuqiong Sun <suny@xxxxxxxxxx>
+ * Stefan Berger <stefanb@xxxxxxxxxxxxxxxxxx>
+ *
+ * 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/ima.h>
+
+#include "ima.h"
+
+int ima_init_namespace(struct ima_namespace *ns)
+{
+#ifdef CONFIG_IMA_NS
+ ns->ns.ops = &imans_operations;
+ return ns_alloc_inum(&ns->ns);
+#else
+ return 0;
+#endif
+}
+
+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,
+ .ucounts = NULL,
+ .parent = NULL,
+};
+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..8e37d7ac5d34
--- /dev/null
+++ b/security/integrity/ima/ima_ns.c
@@ -0,0 +1,162 @@
+/*
+ * Copyright (C) 2016-2018 IBM Corporation
+ * Author:
+ * Yuqiong Sun <suny@xxxxxxxxxx>
+ * Stefan Berger <stefanb@xxxxxxxxxxxxxxxxxx>
+ *
+ * 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/user_namespace.h>
+#include <linux/proc_ns.h>
+#include <linux/kref.h>
+#include <linux/slab.h>
+#include <linux/ima.h>
+
+#include "ima.h"
+
+static struct ucounts *inc_ima_namespaces(struct user_namespace *ns)
+{
+ return inc_ucount(ns, current_euid(), UCOUNT_IMA_NAMESPACES);
+}
+
+static void dec_ima_namespaces(struct ucounts *ucounts)
+{
+ return dec_ucount(ucounts, UCOUNT_IMA_NAMESPACES);
+}
+
+/**
+ * Clone a new ns copying an original ima namespace, setting refcount to 1
+ *
+ * @user_ns: user namespace that current task runs in
+ * @old_ns: old ima namespace to clone
+ * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
+ */
+static struct ima_namespace *create_ima_ns(struct user_namespace *user_ns,
+ struct ima_namespace *old_ns)
+{
+ struct ima_namespace *ns;
+ struct ucounts *ucounts;
+ int err;
+
+ err = -ENOSPC;
+ ucounts = inc_ima_namespaces(user_ns);
+ if (!ucounts)
+ goto fail;
+
+ err = -ENOMEM;
+ ns = kmalloc(sizeof(*ns), GFP_KERNEL);
+ if (!ns)
+ goto fail_dec;
+
+ err = ima_init_namespace(ns);
+ if (err)
+ goto fail_free;
+
+ kref_init(&ns->kref);
+ ns->ns.ops = &imans_operations;
+ ns->parent = get_ima_ns(old_ns);
+ ns->user_ns = get_user_ns(user_ns);
+ ns->ucounts = ucounts;
+
+ return ns;
+
+fail_free:
+ kfree(ns);
+fail_dec:
+ dec_ima_namespaces(ucounts);
+fail:
+ return ERR_PTR(err);
+}
+
+/**
+ * Copy task's ima namespace, or clone it if flags specifies CLONE_NEWNS.
+ *
+ * @bool: whether to copy or just get a reference to it
+ * @user_ns: user namespace that current task runs in
+ * @old_ns: old ima namespace to clone
+ */
+
+struct ima_namespace *copy_ima_ns(bool copy,
+ struct user_namespace *user_ns,
+ struct ima_namespace *old_ns)
+{
+ struct ima_namespace *new_ns;
+
+ get_ima_ns(old_ns);
+ if (!copy)
+ return old_ns;
+
+ new_ns = create_ima_ns(user_ns, old_ns);
+ put_ima_ns(old_ns);
+
+ return new_ns;
+}
+
+static void destroy_ima_ns(struct ima_namespace *ns)
+{
+ put_ima_ns(ns->parent);
+ put_user_ns(ns->user_ns);
+ ns_free_inum(&ns->ns);
+ dec_ima_namespaces(ns->ucounts);
+ kfree(ns);
+}
+
+void free_ima_ns(struct kref *kref)
+{
+ struct ima_namespace *ns;
+
+ ns = container_of(kref, struct ima_namespace, kref);
+
+ destroy_ima_ns(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;
+
+ put_ima_ns(nsproxy->ima_ns);
+ nsproxy->ima_ns = get_ima_ns(ns);
+
+ return 0;
+}
+
+static struct user_namespace *imans_owner(struct ns_common *ns)
+{
+ return to_ima_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations imans_operations = {
+ .name = "ima",
+ .get = imans_get,
+ .put = imans_put,
+ .install = imans_install,
+ .owner = imans_owner,
+};
--
2.14.3