[RFC PATCH v3 1/3] ima: extend clone() with IMA namespace support
Stefan Berger
stefanb at linux.vnet.ibm.com
Wed Mar 28 11:10:12 UTC 2018
On 03/27/2018 07:01 PM, Eric W. Biederman wrote:
> Stefan Berger <stefanb at linux.vnet.ibm.com> writes:
>
>> From: Yuqiong Sun <suny at us.ibm.com>
>>
>> Add new CONFIG_IMA_NS config option. Let clone() create a new IMA
>> namespace upon CLONE_NEWUSER flag. Attach the ima_ns data structure
>> to user_namespace. ima_ns is allocated and freed upon IMA namespace
>> creation and exit, which is tied to USER 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).
> Tying IMA to the user namespace is far better than tying IMA
> to the mount namespace. It may even be the proper answer.
>
>
> You had asked what it would take to unstick this so you won't have
> problems next time you post and I did not get as far as answering.
>
> I had a conversation a while back with Mimi and I believe what was
> agreed was that IMA to start doing it's thing early needs a write
> to securityfs/imafs.
Above you say 'proper answer' for user namespace. Now this sounds like
making it independent.
>
> As such I expect the best way to create the ima namespace is by simply
> writing to securityfs/imafs. Possibly before the user namespace is
> even unshared. That would allow IMA to keep track of things from
> before a container is created.
So you are saying to not tie it to user namespace but make it an
independent namespace and to not use a clone flag (0x1000) but use the
filesystem to spawn a new namespace. Should that be an IMA specific file
or a file that can be shared with other subsystems?
Stefan
>
> Eric
>
>> Changelog:
>> v3:
>> * Use CLONE_NEWUSER instead of CLONE_NEWNW 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 at us.ibm.com>
>> Signed-off-by: Mehmet Kayaalp <mkayaalp at linux.vnet.ibm.com>
>> Signed-off-by: Stefan Berger <stefanb at linux.vnet.ibm.com>
>> ---
>> include/linux/ima.h | 64 ++++++++++++++++++++++++
>> include/linux/user_namespace.h | 4 ++
>> init/Kconfig | 8 +++
>> kernel/user.c | 7 +++
>> kernel/user_namespace.c | 18 +++++++
>> 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 | 37 ++++++++++++++
>> security/integrity/ima/ima_ns.c | 86 ++++++++++++++++++++++++++++++++
>> 10 files changed, 234 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 0e4647e0eb60..8bca67df0ad3 100644
>> --- a/include/linux/ima.h
>> +++ b/include/linux/ima.h
>> @@ -12,6 +12,7 @@
>>
>> #include <linux/fs.h>
>> #include <linux/kexec.h>
>> +#include <linux/user_namespace.h>
>> struct linux_binprm;
>>
>> #ifdef CONFIG_IMA
>> @@ -105,4 +106,67 @@ static inline int ima_inode_removexattr(struct dentry *dentry,
>> return 0;
>> }
>> #endif /* CONFIG_IMA_APPRAISE */
>> +
>> +struct ima_namespace {
>> + struct kref kref;
>> + struct ima_namespace *parent;
>> +};
>> +
>> +extern struct ima_namespace init_ima_ns;
>> +
>> +void imans_install(struct ns_common *new);
>> +
>> +static inline struct ima_namespace *to_ima_ns(struct ns_common *ns)
>> +{
>> + return container_of(ns, struct user_namespace, ns)->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)
>> +{
>> + BUG_ON(!ns);
>> + if (ns)
>> + kref_get(&ns->kref);
>> + return ns;
>> +}
>> +
>> +static inline void put_ima_ns(struct ima_namespace *ns)
>> +{
>> + BUG_ON(!ns);
>> + if (ns)
>> + kref_put(&ns->kref, free_ima_ns);
>> +}
>> +
>> +struct ima_namespace *copy_ima(struct ima_namespace *old_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)
>> +{
>> + return;
>> +}
>> +
>> +static inline struct ima_namespace *copy_ima(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/user_namespace.h b/include/linux/user_namespace.h
>> index d6b74b91096b..8884b22d991c 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,
>> @@ -76,6 +77,9 @@ struct user_namespace {
>> #endif
>> struct ucounts *ucounts;
>> int 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 a9a2e2c86671..a1ad5384e081 100644
>> --- a/init/Kconfig
>> +++ b/init/Kconfig
>> @@ -931,6 +931,14 @@ 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/user.c b/kernel/user.c
>> index 9a20acce460d..31c946f3adce 100644
>> --- a/kernel/user.c
>> +++ b/kernel/user.c
>> @@ -19,6 +19,10 @@
>> #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... ?
>> @@ -66,6 +70,9 @@ struct user_namespace init_user_ns = {
>> .persistent_keyring_register_sem =
>> __RWSEM_INITIALIZER(init_user_ns.persistent_keyring_register_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 246d4d4ce5c7..7d6e7d6e6a34 100644
>> --- a/kernel/user_namespace.c
>> +++ b/kernel/user_namespace.c
>> @@ -25,6 +25,7 @@
>> #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);
>> @@ -140,8 +141,20 @@ int create_user_ns(struct cred *new)
>> if (!setup_userns_sysctls(ns))
>> goto fail_keyring;
> Having the functions be #ifdef'd rather than the code would
> be preferabble.
>>
>> +#if CONFIG_IMA
>> + ns->ima_ns = copy_ima(parent_ns->ima_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);
>> @@ -195,6 +208,9 @@ 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);
>> #ifdef CONFIG_PERSISTENT_KEYRINGS
>> key_put(ns->persistent_keyring_register);
>> @@ -1285,6 +1301,8 @@ static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns)
>> put_user_ns(cred->user_ns);
>> set_cred_user_ns(cred, get_user_ns(user_ns));
>>
>> + imans_install(ns);
>> +
>> return commit_creds(cred);
>> }
>>
>> 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..e98c11c7cf75 100644
>> --- a/security/integrity/ima/ima.h
>> +++ b/security/integrity/ima/ima.h
>> @@ -291,6 +291,10 @@ 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
>>
>> diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
>> index 2967d497a665..7f884a71fa1c 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..52cb94b1d392
>> --- /dev/null
>> +++ b/security/integrity/ima/ima_init_ima_ns.c
>> @@ -0,0 +1,37 @@
>> +/*
>> + * Copyright (C) 2016-2018 IBM Corporation
>> + * Author:
>> + * Yuqiong Sun <suny at us.ibm.com>
>> + * Stefan Berger <stefanb at 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>
>> +
>> +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),
>> + .parent = NULL,
>> +};
>> +EXPORT_SYMBOL(init_ima_ns);
>> +
>> +void imans_install(struct ns_common *new)
>> +{
>> + struct ima_namespace *ns = to_ima_ns(new);
>> +
>> + get_ima_ns(ns);
>> +}
>> diff --git a/security/integrity/ima/ima_ns.c b/security/integrity/ima/ima_ns.c
>> new file mode 100644
>> index 000000000000..62148908015a
>> --- /dev/null
>> +++ b/security/integrity/ima/ima_ns.c
>> @@ -0,0 +1,86 @@
>> +/*
>> + * Copyright (C) 2016-2018 IBM Corporation
>> + * Author:
>> + * Yuqiong Sun <suny at us.ibm.com>
>> + * Stefan Berger <stefanb at 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 "ima.h"
>> +
>> +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
>> + * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
>> + */
>> +static struct ima_namespace *clone_ima_ns(struct ima_namespace *old_ns)
>> +{
>> + struct ima_namespace *ns;
>> +
>> + ns = create_ima_ns();
>> + if (!ns)
>> + return ERR_PTR(-ENOMEM);
>> +
>> + get_ima_ns(old_ns);
>> + ns->parent = old_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
>> + * @old_ns: old ima namespace to clone
>> + */
>> +
>> +struct ima_namespace *copy_ima(struct ima_namespace *old_ns)
>> +{
>> + struct ima_namespace *new_ns;
>> +
>> + BUG_ON(!old_ns);
>> + get_ima_ns(old_ns);
>> +
>> + new_ns = clone_ima_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);
>> + kfree(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);
>> +}
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