[RFC PATCH v2 1/3] ima: extend clone() with IMA namespace support
Stefan Berger
stefanb at linux.vnet.ibm.com
Thu Mar 15 15:26:57 UTC 2018
On 03/15/2018 06:40 AM, 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_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).
> IMA is not path based. The only thing that belongs to a mount
> namespace are paths. Therefore IMA is completely inappropriate to
> be joint with a mount namespace.
IMA measures the files described by these paths. The files also may hold
signatures (security.ima xattr) needed for IMA appraisal.
>
> I saw that Serge even recently mentioned that you need to take
> this aspect of the changes back to the drawing board. With my
> namespace maintainer hat on I repeat that.
Drawing board is here now (tuning on the text...):
http://kernsec.org/wiki/index.php/IMA_Namespacing_design_considerations
>
> From a 10,000 foot view I can already tell that this is hopeless.
> So for binding IMA namspaces and CLONE_NEWNS:
>
> Nacked-by: "Eric W. Biederman" <ebiederm at xmission.com>
>
> I am not nacking IMA namespacing just inappropriately tying ima
> namespaces to mount namespaces. These should be completely separate
> entities.
Let's say we go down the road of spawning it independently. Can we use
the unused clone flag 0x1000? Or should we come up with new
unshare2()/clone2() syscalls to extend the clone bits to 64 bit? Or use
a sysfs/securityfs file to spawn a new IMA namespace? Make this a
generic file not an IMA specific one?
Stefan
>
> Eric
>
>
>> 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()
>> * Moved ima_init_ns and related functions into own file that is
>> always compiled
>> * Fixed putting of imans->parent
>> * Move IMA namespace creation from nsproxy into mount namespace
>> code
>>
>> 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>
>> ---
>> fs/mount.h | 14 -----
>> fs/namespace.c | 29 ++++++++--
>> include/linux/ima.h | 67 +++++++++++++++++++++++
>> include/linux/mount.h | 20 ++++++-
>> init/Kconfig | 8 +++
>> kernel/nsproxy.c | 1 +
>> 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 | 38 +++++++++++++
>> security/integrity/ima/ima_ns.c | 91 ++++++++++++++++++++++++++++++++
>> 11 files changed, 260 insertions(+), 19 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/mount.h b/fs/mount.h
>> index f39bc9da4d73..e19ebde97756 100644
>> --- a/fs/mount.h
>> +++ b/fs/mount.h
>> @@ -5,20 +5,6 @@
>> #include <linux/ns_common.h>
>> #include <linux/fs_pin.h>
>>
>> -struct mnt_namespace {
>> - atomic_t count;
>> - struct ns_common ns;
>> - struct mount * root;
>> - struct list_head list;
>> - struct user_namespace *user_ns;
>> - struct ucounts *ucounts;
>> - u64 seq; /* Sequence number to prevent loops */
>> - wait_queue_head_t poll;
>> - u64 event;
>> - unsigned int mounts; /* # of mounts in the namespace */
>> - unsigned int pending_mounts;
>> -} __randomize_layout;
>> -
>> struct mnt_pcp {
>> int mnt_count;
>> int mnt_writers;
>> diff --git a/fs/namespace.c b/fs/namespace.c
>> index 9d1374ab6e06..7f886c02278b 100644
>> --- a/fs/namespace.c
>> +++ b/fs/namespace.c
>> @@ -26,6 +26,7 @@
>> #include <linux/bootmem.h>
>> #include <linux/task_work.h>
>> #include <linux/sched/task.h>
>> +#include <linux/ima.h>
>>
>> #include "pnode.h"
>> #include "internal.h"
>> @@ -2858,6 +2859,7 @@ static void dec_mnt_namespaces(struct ucounts *ucounts)
>>
>> static void free_mnt_ns(struct mnt_namespace *ns)
>> {
>> + put_ima_ns(ns->ima_ns);
>> ns_free_inum(&ns->ns);
>> dec_mnt_namespaces(ns->ucounts);
>> put_user_ns(ns->user_ns);
>> @@ -2873,11 +2875,13 @@ static void free_mnt_ns(struct mnt_namespace *ns)
>> */
>> static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1);
>>
>> -static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
>> +static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns,
>> + struct ima_namespace *ima_ns)
>> {
>> struct mnt_namespace *new_ns;
>> struct ucounts *ucounts;
>> int ret;
>> + int err;
>>
>> ucounts = inc_mnt_namespaces(user_ns);
>> if (!ucounts)
>> @@ -2894,6 +2898,20 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
>> dec_mnt_namespaces(ucounts);
>> return ERR_PTR(ret);
>> }
>> +
>> + if (ima_ns == NULL) {
>> + new_ns->ima_ns = get_ima_ns(&init_ima_ns);
>> + } else {
>> + new_ns->ima_ns = copy_ima(user_ns, ima_ns);
>> + if (IS_ERR(new_ns->ima_ns)) {
>> + err = PTR_ERR(new_ns->ima_ns);
>> + ns_free_inum(&new_ns->ns);
>> + kfree(new_ns);
>> + dec_mnt_namespaces(ucounts);
>> + return ERR_PTR(err);
>> + }
>> + }
>> +
>> new_ns->ns.ops = &mntns_operations;
>> new_ns->seq = atomic64_add_return(1, &mnt_ns_seq);
>> atomic_set(&new_ns->count, 1);
>> @@ -2920,6 +2938,7 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
>> int copy_flags;
>>
>> BUG_ON(!ns);
>> + BUG_ON(!ns->ima_ns);
>>
>> if (likely(!(flags & CLONE_NEWNS))) {
>> get_mnt_ns(ns);
>> @@ -2928,7 +2947,7 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
>>
>> old = ns->root;
>>
>> - new_ns = alloc_mnt_ns(user_ns);
>> + new_ns = alloc_mnt_ns(user_ns, ns->ima_ns);
>> if (IS_ERR(new_ns))
>> return new_ns;
>>
>> @@ -2989,7 +3008,8 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
>> */
>> static struct mnt_namespace *create_mnt_ns(struct vfsmount *m)
>> {
>> - struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns);
>> + struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns,
>> + NULL);
>> if (!IS_ERR(new_ns)) {
>> struct mount *mnt = real_mount(m);
>> mnt->mnt_ns = new_ns;
>> @@ -3497,6 +3517,9 @@ static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns)
>> set_fs_root(fs, &root);
>>
>> path_put(&root);
>> +
>> + imans_install(nsproxy, ns);
>> +
>> return 0;
>> }
>>
>> diff --git a/include/linux/ima.h b/include/linux/ima.h
>> index 0e4647e0eb60..fd150dfde277 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/mount.h>
>> struct linux_binprm;
>>
>> #ifdef CONFIG_IMA
>> @@ -105,4 +106,70 @@ 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 ima_namespace *parent;
>> +};
>> +
>> +extern struct ima_namespace init_ima_ns;
>> +
>> +void imans_install(struct nsproxy *nsproxy, struct ns_common *new);
>> +
>> +static inline struct ima_namespace *to_ima_ns(struct ns_common *ns)
>> +{
>> + return container_of(ns, struct mnt_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 user_namespace *user_ns,
>> + struct ima_namespace *old_ns);
>> +
>> +static inline struct ima_namespace *get_current_ns(void)
>> +{
>> + return current->nsproxy->mnt_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 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/mount.h b/include/linux/mount.h
>> index 45b1f56c6c2f..361c962ebd3d 100644
>> --- a/include/linux/mount.h
>> +++ b/include/linux/mount.h
>> @@ -16,11 +16,29 @@
>> #include <linux/spinlock.h>
>> #include <linux/seqlock.h>
>> #include <linux/atomic.h>
>> +#include <linux/ns_common.h>
>> +#include <linux/wait.h>
>>
>> struct super_block;
>> struct vfsmount;
>> struct dentry;
>> -struct mnt_namespace;
>> +struct ima_namespace;
>> +
>> +struct mnt_namespace {
>> + atomic_t count;
>> + struct ns_common ns;
>> + struct mount * root;
>> + struct list_head list;
>> + struct user_namespace *user_ns;
>> + struct ucounts *ucounts;
>> + u64 seq; /* Sequence number to prevent loops */
>> + wait_queue_head_t poll;
>> + u64 event;
>> + unsigned int mounts; /* # of mounts in the namespace */
>> + unsigned int pending_mounts;
>> + struct ima_namespace *ima_ns;
>> +} __randomize_layout;
>> +
>>
>> #define MNT_NOSUID 0x01
>> #define MNT_NODEV 0x02
>> 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/nsproxy.c b/kernel/nsproxy.c
>> index f6c5d330059a..7d1a35362186 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;
>>
>> 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..4b081dbfac07
>> --- /dev/null
>> +++ b/security/integrity/ima/ima_init_ima_ns.c
>> @@ -0,0 +1,38 @@
>> +/*
>> + * Copyright (C) 2016-2018 IBM Corporation
>> + * Author: Yuqiong Sun <suny at us.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(2),
>> + .user_ns = &init_user_ns,
>> + .parent = NULL,
>> +};
>> +EXPORT_SYMBOL(init_ima_ns);
>> +
>> +void imans_install(struct nsproxy *nsproxy, struct ns_common *new)
>> +{
>> + struct ima_namespace *ns = to_ima_ns(new);
>> +
>> + get_ima_ns(ns);
>> + put_ima_ns(nsproxy->mnt_ns->ima_ns);
>> + nsproxy->mnt_ns->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..7ab4322c88ae
>> --- /dev/null
>> +++ b/security/integrity/ima/ima_ns.c
>> @@ -0,0 +1,91 @@
>> +/*
>> + * Copyright (C) 2016-2018 IBM Corporation
>> + * Author: Yuqiong Sun <suny at us.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/user_namespace.h>
>> +#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
>> + * @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;
>> +
>> + ns = create_ima_ns();
>> + if (!ns)
>> + return ERR_PTR(-ENOMEM);
>> +
>> + 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(struct user_namespace *user_ns,
>> + struct ima_namespace *old_ns)
>> +{
>> + struct ima_namespace *new_ns;
>> +
>> + BUG_ON(!old_ns);
>> + get_ima_ns(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);
>> + 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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