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

Stefan Berger
2021-11-30T16:07:23Z

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