[RFC PATCH v2 1/3] x86/sgx: Add SGX specific LSM hooks

[Casey Schaufler]

On 6/27/2019 11:56 AM, Cedric Xing wrote:
> SGX enclaves are loaded from pages in regular memory. Given the ability to
> create executable pages, the newly added SGX subsystem may present a backdoor
> for adversaries to circumvent LSM policies, such as creating an executable
> enclave page from a modified regular page that would otherwise not be made
> executable as prohibited by LSM. Therefore arises the primary question of
> whether an enclave page should be allowed to be created from a given source
> page in regular memory.
>
> A related question is whether to grant/deny a mprotect() request on a given
> enclave page/range. mprotect() is traditionally covered by
> security_file_mprotect() hook, however, enclave pages have a different lifespan
> than either MAP_PRIVATE or MAP_SHARED. Particularly, MAP_PRIVATE pages have the
> same lifespan as the VMA while MAP_SHARED pages have the same lifespan as the
> backing file (on disk), but enclave pages have the lifespan of the enclave’s
> file descriptor. For example, enclave pages could be munmap()’ed then mmap()’ed
> again without losing contents (like MAP_SHARED), but all enclave pages will be
> lost once its file descriptor has been closed (like MAP_PRIVATE). That said,
> LSM modules need some new data structure for tracking protections of enclave
> pages/ranges so that they can make proper decisions at mmap()/mprotect()
> syscalls.
>
> The last question, which is orthogonal to the 2 above, is whether or not to
> allow a given enclave to launch/run. Enclave pages are not visible to the rest
> of the system, so to some extent offer a better place for malicious software to
> hide. Thus, it is sometimes desirable to whitelist/blacklist enclaves by their
> measurements, signing public keys, or image files.
>
> To address the questions above, 2 new LSM hooks are added for enclaves.
>   - security_enclave_load() – This hook allows LSM to decide whether or not to
>     allow instantiation of a range of enclave pages using the specified VMA. It
>     is invoked when a range of enclave pages is about to be loaded. It serves 3
>     purposes: 1) indicate to LSM that the file struct in subject is an enclave;
>     2) allow LSM to decide whether or not to instantiate those pages and 3)
>     allow LSM to initialize internal data structures for tracking
>     origins/protections of those pages.
>   - security_enclave_init() – This hook allows whitelisting/blacklisting or
>     performing whatever checks deemed appropriate before an enclave is allowed
>     to run. An LSM module may opt to use the file backing the SIGSTRUCT as a
>     proxy to dictate allowed protections for anonymous pages.
>
> mprotect() of enclave pages continue to be governed by
> security_file_mprotect(), with the expectation that LSM is able to distinguish
> between regular and enclave pages inside the hook. For mmap(), the SGX
> subsystem is expected to invoke security_file_mprotect() explicitly to check
> protections against the requested protections for existing enclave pages. As
> stated earlier, enclave pages have different lifespan than the existing
> MAP_PRIVATE and MAP_SHARED pages, so would require a new data structure outside
> of VMA to track their protections and/or origins. Enclave Memory Area (or EMA
> for short) has been introduced to address the need. EMAs are maintained by the
> LSM framework for all LSM modules to share. EMAs will be instantiated for
> enclaves only so will not impose memory/performance overheads for regular
> applications/files. Please see include/linux/lsm_ema.h and security/lsm_ema.c
> for details.
>
> A new setup parameter – lsm.ema.cache_decisions has been introduced to offer
> the choice between memory consumption and accuracy of audit logs. Enabling
> lsm.ema.cache_decisions causes LSM framework NOT to keep backing files open for
> EMAs. While that saves memory, it requires LSM modules to make and cache
> decisions ahead of time, and makes it difficult for LSM modules to generate
> accurate audit logs. System administrators are expected to run LSM in
> permissive mode with lsm.ema.cache_decisions off to determine the minimal
> permissions needed, and then turn it back on in enforcing mode for optimal
> performance and memory usage. lsm.ema.cache_decisions is on by default and
> could be turned off by appending “lsm.ema.cache_decisions=0” or
> “lsm.ema.cache_decisions=off” to the kernel command line.
>
> Signed-off-by: Cedric Xing <cedric.xing at intel.com>
> ---
>  include/linux/lsm_ema.h   | 171 ++++++++++++++++++++++++++++++++++++++
>  include/linux/lsm_hooks.h |  29 +++++++
>  include/linux/security.h  |  23 +++++
>  security/Makefile         |   1 +
>  security/lsm_ema.c        | 132 +++++++++++++++++++++++++++++
>  security/security.c       |  47 ++++++++++-
>  6 files changed, 402 insertions(+), 1 deletion(-)
>  create mode 100644 include/linux/lsm_ema.h
>  create mode 100644 security/lsm_ema.c

Don't use "lsm_ema". This isn't LSM infrastructure.
Three letter abbreviations are easy to type, but are
doomed to encounter conflicts and lead to confusion.
I suggest that you use "enclave", because it doesn't
start off conflicting with anything and is descriptive.

This code should not be mixed in with the LSM infrastructure.
It should all be contained in its own module, under
security/enclave.

> diff --git a/include/linux/lsm_ema.h b/include/linux/lsm_ema.h
> new file mode 100644
> index 000000000000..a09b8f96da05
> --- /dev/null
> +++ b/include/linux/lsm_ema.h

There's no need for this header to be used outside the enclave
LSM. It should be "security/enclave/enclave.h"


> @@ -0,0 +1,171 @@
> +/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
> +/**
> + * Enclave Memory Area interface for LSM modules
> + *
> + * Copyright(c) 2016-19 Intel Corporation.
> + */
> +
> +#ifndef _LSM_EMA_H_
> +#define _LSM_EMA_H_
> +
> +#include <linux/list.h>
> +#include <linux/mutex.h>
> +#include <linux/fs.h>
> +#include <linux/file.h>
> +
> +/**
> + * lsm_ema - LSM Enclave Memory Area structure

How about s/lsm_ema/enclave/ ?

> + *
> + * Data structure to track origins of enclave pages
> + *
> + * @link:
> + *	Link to adjacent EMAs. EMAs are sorted by their addresses in ascending
> + *	order
> + * @start:
> + *	Starting address
> + * @end:
> + *	Ending address
> + * @source:
> + *	File from which this range was loaded from, or NULL if not loaded from
> + *	any files
> + */
> +struct lsm_ema {
> +	struct list_head	link;
> +	size_t			start;
> +	size_t			end;
> +	struct file		*source;
> +};
> +
> +#define lsm_ema_data(ema, blob_sizes)	\
> +	((char *)((struct lsm_ema *)(ema) + 1) + blob_sizes.lbs_ema_data)

Who uses this? The enclave LSM? Convention would have this
be selinux_enclave(ema) for the SELinux code. This is
inconsistent with the way other blobs are handled.

> +
> +/**
> + * lsm_ema_map - LSM Enclave Memory Map structure

enclave_map

> + *
> + * Container for EMAs of an enclave
> + *
> + * @list:
> + *	Head of a list of sorted EMAs
> + * @lock:
> + *	Acquire before querying/updateing the list EMAs
> + */
> +struct lsm_ema_map {
> +	struct list_head	list;
> +	struct mutex		lock;
> +};
> +
> +/**
> + * These are functions to be used by the LSM framework, and must be defined
> + * regardless CONFIG_INTEL_SGX is enabled or not.

Not acceptable for the LSM infrastructure. They
are inconsistent with the way data is used there.

> + */
> +
> +#ifdef CONFIG_INTEL_SGX
> +void lsm_ema_global_init(size_t);
> +void lsm_free_ema_map(atomic_long_t *);
> +#else
> +static inline void lsm_ema_global_init(size_t ema_data_size)
> +{
> +}
> +
> +static inline void lsm_free_ema_map(atomic_long_t *p)
> +{
> +}
> +#endif
> +
> +/**
> + * Below are APIs to be used by LSM modules
> + */
> +
> +struct lsm_ema_map *lsm_init_or_get_ema_map(atomic_long_t *);
> +struct lsm_ema *lsm_alloc_ema(void);

Do you mean security_alloc_enclave()?
That would go into security/security.h

> +void lsm_free_ema(struct lsm_ema *);

Do you mean security_free_enclave()?
That would go into security/security.h

> +void lsm_init_ema(struct lsm_ema *, size_t, size_t, struct file *);

This goes in the enclave LSM.

> +int lsm_merge_ema(struct lsm_ema *, struct lsm_ema_map *);
> +struct lsm_ema *lsm_split_ema(struct lsm_ema *, size_t, struct lsm_ema_map *);
> +
> +static inline struct lsm_ema_map *lsm_get_ema_map(struct file *f)
> +{
> +	return (void *)atomic_long_read(f->f_security);
> +}
> +
> +static inline int __must_check lsm_lock_ema(struct lsm_ema_map *map)
> +{
> +	return mutex_lock_interruptible(&map->lock);
> +}
> +
> +static inline void lsm_unlock_ema(struct lsm_ema_map *map)
> +{
> +	mutex_unlock(&map->lock);
> +}
> +
> +static inline struct lsm_ema *lsm_prev_ema(struct lsm_ema *p,
> +					   struct lsm_ema_map *map)
> +{
> +	p = list_prev_entry(p, link);
> +	return &p->link == &map->list ? NULL : p;
> +}
> +
> +static inline struct lsm_ema *lsm_next_ema(struct lsm_ema *p,
> +					   struct lsm_ema_map *map)
> +{
> +	p = list_next_entry(p, link);
> +	return &p->link == &map->list ? NULL : p;
> +}
> +
> +static inline struct lsm_ema *lsm_find_ema(struct lsm_ema_map *map, size_t a)
> +{
> +	struct lsm_ema *p;
> +
> +	BUG_ON(!mutex_is_locked(&map->lock));
> +
> +	list_for_each_entry(p, &map->list, link)
> +		if (a < p->end)
> +			break;
> +	return &p->link == &map->list ? NULL : p;
> +}
> +
> +static inline int lsm_insert_ema(struct lsm_ema_map *map, struct lsm_ema *n)
> +{
> +	struct lsm_ema *p = lsm_find_ema(map, n->start);
> +
> +	if (!p)
> +		list_add_tail(&n->link, &map->list);
> +	else if (n->end <= p->start)
> +		list_add_tail(&n->link, &p->link);
> +	else
> +		return -EEXIST;
> +
> +	lsm_merge_ema(n, map);
> +	if (p)
> +		lsm_merge_ema(p, map);
> +	return 0;
> +}
> +
> +static inline int lsm_for_each_ema(struct lsm_ema_map *map, size_t start,
> +				   size_t end, int (*cb)(struct lsm_ema *,
> +							 void *), void *arg)
> +{
> +	struct lsm_ema *ema;
> +	int rc;
> +
> +	ema = lsm_find_ema(map, start);
> +	while (ema && end > ema->start) {
> +		if (start > ema->start)
> +			lsm_split_ema(ema, start, map);
> +		if (end < ema->end)
> +			ema = lsm_split_ema(ema, end, map);
> +
> +		rc = (*cb)(ema, arg);
> +		lsm_merge_ema(ema, map);
> +		if (rc)
> +			return rc;
> +
> +		ema = lsm_next_ema(ema, map);
> +	}
> +
> +	if (ema)
> +		lsm_merge_ema(ema, map);
> +	return 0;
> +}

There is no way that these belong as part of the LSM
infrastructure. If you need an enclave management API
you need to find some other place for it.

> +
> +#endif /* _LSM_EMA_H_ */
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index 47f58cfb6a19..ade1f9f81e64 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -29,6 +29,8 @@
>  #include <linux/init.h>
>  #include <linux/rculist.h>
>  
> +struct lsm_ema;
> +
>  /**
>   * union security_list_options - Linux Security Module hook function list
>   *
> @@ -1446,6 +1448,21 @@
>   * @bpf_prog_free_security:
>   *	Clean up the security information stored inside bpf prog.
>   *
> + * @enclave_load:
> + *	Decide if a range of pages shall be allowed to be loaded into an
> + *	enclave
> + *
> + *	@encl points to the file identifying the target enclave
> + *	@ema specifies the target range to be loaded
> + *	@flags contains protections being requested for the target range
> + *	@source points to the VMA containing the source pages to be loaded
> + *
> + * @enclave_init:
> + *	Decide if an enclave shall be allowed to launch
> + *
> + *	@encl points to the file identifying the target enclave being launched
> + *	@sigstruct contains a copy of the SIGSTRUCT in kernel memory
> + *	@source points to the VMA backing SIGSTRUCT in user memory
>   */
>  union security_list_options {
>  	int (*binder_set_context_mgr)(struct task_struct *mgr);
> @@ -1807,6 +1824,13 @@ union security_list_options {
>  	int (*bpf_prog_alloc_security)(struct bpf_prog_aux *aux);
>  	void (*bpf_prog_free_security)(struct bpf_prog_aux *aux);
>  #endif /* CONFIG_BPF_SYSCALL */
> +
> +#ifdef CONFIG_INTEL_SGX
> +	int (*enclave_load)(struct file *encl, struct lsm_ema *ema,
> +			    size_t flags, struct vm_area_struct *source);
> +	int (*enclave_init)(struct file *encl, struct sgx_sigstruct *sigstruct,
> +			    struct vm_area_struct *source);
> +#endif
>  };
>  
>  struct security_hook_heads {
> @@ -2046,6 +2070,10 @@ struct security_hook_heads {
>  	struct hlist_head bpf_prog_alloc_security;
>  	struct hlist_head bpf_prog_free_security;
>  #endif /* CONFIG_BPF_SYSCALL */
> +#ifdef CONFIG_INTEL_SGX
> +	struct hlist_head enclave_load;
> +	struct hlist_head enclave_init;
> +#endif
>  } __randomize_layout;
>  
>  /*
> @@ -2069,6 +2097,7 @@ struct lsm_blob_sizes {
>  	int	lbs_ipc;
>  	int	lbs_msg_msg;
>  	int	lbs_task;
> +	int	lbs_ema_data;

Is a module like SELinux expected to have its own
data for enclave? That's the only case where you would
have a enclave entry in the blob.

>  };
>  
>  /*
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 659071c2e57c..52c200810004 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -1829,5 +1829,28 @@ static inline void security_bpf_prog_free(struct bpf_prog_aux *aux)
>  #endif /* CONFIG_SECURITY */
>  #endif /* CONFIG_BPF_SYSCALL */
>  
> +#ifdef CONFIG_INTEL_SGX
> +struct sgx_sigstruct;
> +#ifdef CONFIG_SECURITY
> +int security_enclave_load(struct file *encl, size_t start, size_t end,
> +			  size_t flags, struct vm_area_struct *source);
> +int security_enclave_init(struct file *encl, struct sgx_sigstruct *sigstruct,
> +			  struct vm_area_struct *source);
> +#else
> +static inline int security_enclave_load(struct file *encl, size_t start,
> +					size_t end, struct vm_area_struct *src)
> +{
> +	return 0;
> +}
> +
> +static inline int security_enclave_init(struct file *encl,
> +					struct sgx_sigstruct *sigstruct,
> +					struct vm_area_struct *src)
> +{
> +	return 0;
> +}
> +#endif /* CONFIG_SECURITY */
> +#endif /* CONFIG_INTEL_SGX */
> +
>  #endif /* ! __LINUX_SECURITY_H */
>  
> diff --git a/security/Makefile b/security/Makefile
> index c598b904938f..1bab8f1344b6 100644
> --- a/security/Makefile
> +++ b/security/Makefile
> @@ -28,6 +28,7 @@ obj-$(CONFIG_SECURITY_YAMA)		+= yama/
>  obj-$(CONFIG_SECURITY_LOADPIN)		+= loadpin/
>  obj-$(CONFIG_SECURITY_SAFESETID)       += safesetid/
>  obj-$(CONFIG_CGROUP_DEVICE)		+= device_cgroup.o
> +obj-$(CONFIG_INTEL_SGX)			+= lsm_ema.o

This belongs in a subdirectory.

>  
>  # Object integrity file lists
>  subdir-$(CONFIG_INTEGRITY)		+= integrity
> diff --git a/security/lsm_ema.c b/security/lsm_ema.c
> new file mode 100644
> index 000000000000..68fae0724d37
> --- /dev/null
> +++ b/security/lsm_ema.c
> @@ -0,0 +1,132 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> +// Copyright(c) 2016-18 Intel Corporation.
> +
> +#include <linux/lsm_ema.h>
> +#include <linux/slab.h>
> +
> +static struct kmem_cache *lsm_ema_cache;
> +static size_t lsm_ema_data_size;
> +static int lsm_ema_cache_decisions = 1;
> +
> +void lsm_ema_global_init(size_t ema_size)
> +{
> +	BUG_ON(lsm_ema_data_size > 0);
> +
> +	lsm_ema_data_size = ema_size;
> +
> +	ema_size += sizeof(struct lsm_ema);
> +	ema_size = max(ema_size, sizeof(struct lsm_ema_map));
> +	lsm_ema_cache = kmem_cache_create("lsm_ema_cache", ema_size,
> +					  __alignof__(struct lsm_ema),
> +					  SLAB_PANIC, NULL);
> +
> +}
> +
> +struct lsm_ema_map *lsm_init_or_get_ema_map(atomic_long_t *p)
> +{
> +	struct lsm_ema_map *map;
> +
> +	map = (typeof(map))atomic_long_read(p);
> +	if (!map) {
> +		long n;
> +
> +		map = (typeof(map))lsm_alloc_ema();
> +		if (!map)
> +			return NULL;
> +
> +		INIT_LIST_HEAD(&map->list);
> +		mutex_init(&map->lock);
> +
> +		n = atomic_long_cmpxchg(p, 0, (long)map);
> +		if (n) {
> +			atomic_long_t a;
> +			atomic_long_set(&a, (long)map);
> +			map = (typeof(map))n;
> +			lsm_free_ema_map(&a);
> +		}
> +	}
> +	return map;
> +}
> +
> +void lsm_free_ema_map(atomic_long_t *p)
> +{
> +	struct lsm_ema_map *map;
> +	struct lsm_ema *ema, *n;
> +
> +	map = (typeof(map))atomic_long_read(p);
> +	if (!map)
> +		return;
> +
> +	BUG_ON(mutex_is_locked(&map->lock));
> +
> +	list_for_each_entry_safe(ema, n, &map->list, link)
> +		lsm_free_ema(ema);
> +	kmem_cache_free(lsm_ema_cache, map);
> +}
> +
> +struct lsm_ema *lsm_alloc_ema(void)
> +{
> +	return kmem_cache_zalloc(lsm_ema_cache, GFP_KERNEL);
> +}
> +
> +void lsm_free_ema(struct lsm_ema *ema)
> +{
> +	list_del(&ema->link);
> +	if (ema->source)
> +		fput(ema->source);
> +	kmem_cache_free(lsm_ema_cache, ema);
> +}
> +
> +void lsm_init_ema(struct lsm_ema *ema, size_t start, size_t end,
> +		  struct file *source)
> +{
> +	INIT_LIST_HEAD(&ema->link);
> +	ema->start = start;
> +	ema->end = end;
> +	if (!lsm_ema_cache_decisions && source)
> +		ema->source = get_file(source);
> +}
> +
> +int lsm_merge_ema(struct lsm_ema *p, struct lsm_ema_map *map)
> +{
> +	struct lsm_ema *prev = list_prev_entry(p, link);
> +
> +	BUG_ON(!mutex_is_locked(&map->lock));
> +
> +	if (&prev->link == &map->list || prev->end != p->start ||
> +	    prev->source != p->source ||
> +	    memcmp(prev + 1, p + 1, lsm_ema_data_size))
> +		return 0;
> +
> +	p->start = prev->start;
> +	fput(prev->source);
> +	lsm_free_ema(prev);
> +	return 1;
> +}
> +
> +struct lsm_ema *lsm_split_ema(struct lsm_ema *p, size_t at,
> +			      struct lsm_ema_map *map)
> +{
> +	struct lsm_ema *n;
> +
> +	BUG_ON(!mutex_is_locked(&map->lock));
> +
> +	if (at <= p->start || at >= p->end)
> +		return p;
> +
> +	n = lsm_alloc_ema();
> +	if (likely(n)) {
> +		lsm_init_ema(n, p->start, at, p->source);
> +		memcpy(n + 1, p + 1, lsm_ema_data_size);
> +		p->start = at;
> +		list_add_tail(&n->link, &p->link);
> +	}
> +	return n;
> +}
> +
> +static int __init set_ema_cache_decisions(char *str)
> +{
> +	lsm_ema_cache_decisions = (strcmp(str, "0") && strcmp(str, "off"));
> +	return 1;
> +}
> +__setup("lsm.ema.cache_decisions=", set_ema_cache_decisions);
> diff --git a/security/security.c b/security/security.c
> index f493db0bf62a..d50883f18be2 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -17,6 +17,7 @@
>  #include <linux/init.h>
>  #include <linux/kernel.h>
>  #include <linux/lsm_hooks.h>
> +#include <linux/lsm_ema.h>
>  #include <linux/integrity.h>
>  #include <linux/ima.h>
>  #include <linux/evm.h>
> @@ -41,7 +42,9 @@ static struct kmem_cache *lsm_file_cache;
>  static struct kmem_cache *lsm_inode_cache;
>  
>  char *lsm_names;
> -static struct lsm_blob_sizes blob_sizes __lsm_ro_after_init;
> +static struct lsm_blob_sizes blob_sizes __lsm_ro_after_init = {
> +	.lbs_file = sizeof(atomic_long_t) * IS_ENABLED(CONFIG_INTEL_SGX),
> +};

This belongs in the module specific code.
It does not belong here.

>  
>  /* Boot-time LSM user choice */
>  static __initdata const char *chosen_lsm_order;
> @@ -169,6 +172,7 @@ static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed)
>  	lsm_set_blob_size(&needed->lbs_ipc, &blob_sizes.lbs_ipc);
>  	lsm_set_blob_size(&needed->lbs_msg_msg, &blob_sizes.lbs_msg_msg);
>  	lsm_set_blob_size(&needed->lbs_task, &blob_sizes.lbs_task);
> +	lsm_set_blob_size(&needed->lbs_ema_data, &blob_sizes.lbs_ema_data);
>  }
>  
>  /* Prepare LSM for initialization. */
> @@ -314,6 +318,7 @@ static void __init ordered_lsm_init(void)
>  		lsm_inode_cache = kmem_cache_create("lsm_inode_cache",
>  						    blob_sizes.lbs_inode, 0,
>  						    SLAB_PANIC, NULL);
> +	lsm_ema_global_init(blob_sizes.lbs_ema_data);
>  
>  	lsm_early_cred((struct cred *) current->cred);
>  	lsm_early_task(current);
> @@ -1357,6 +1362,7 @@ void security_file_free(struct file *file)
>  	blob = file->f_security;
>  	if (blob) {
>  		file->f_security = NULL;
> +		lsm_free_ema_map(blob);
>  		kmem_cache_free(lsm_file_cache, blob);
>  	}
>  }
> @@ -1420,6 +1426,7 @@ int security_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
>  {
>  	return call_int_hook(file_mprotect, 0, vma, reqprot, prot);
>  }
> +EXPORT_SYMBOL(security_file_mprotect);
>  
>  int security_file_lock(struct file *file, unsigned int cmd)
>  {
> @@ -2355,3 +2362,41 @@ void security_bpf_prog_free(struct bpf_prog_aux *aux)
>  	call_void_hook(bpf_prog_free_security, aux);
>  }
>  #endif /* CONFIG_BPF_SYSCALL */
> +
> +#ifdef CONFIG_INTEL_SGX
> +int security_enclave_load(struct file *encl, size_t start, size_t end,
> +			  size_t flags, struct vm_area_struct *src)

You are mixing module specific code into the infrastructure.
All of this should be in the enclave code. None of it should be here.

> +{
> +	struct lsm_ema_map *map;
> +	struct lsm_ema *ema;
> +	int rc;
> +
> +	map = lsm_init_or_get_ema_map(encl->f_security);
> +	if (unlikely(!map))
> +		return -ENOMEM;
> +
> +	ema = lsm_alloc_ema();
> +	if (unlikely(!ema))
> +		return -ENOMEM;
> +
> +	lsm_init_ema(ema, start, end, src->vm_file);
> +	rc = call_int_hook(enclave_load, 0, encl, ema, flags, src);
> +	if (!rc)
> +		rc = lsm_lock_ema(map);
> +	if (!rc) {
> +		rc = lsm_insert_ema(map, ema);
> +		lsm_unlock_ema(map);
> +	}
> +	if (rc)
> +		lsm_free_ema(ema);
> +	return rc;
> +}
> +EXPORT_SYMBOL(security_enclave_load);
> +
> +int security_enclave_init(struct file *encl, struct sgx_sigstruct *sigstruct,
> +			  struct vm_area_struct *src)
> +{
> +	return call_int_hook(enclave_init, 0, encl, sigstruct, src);
> +}
> +EXPORT_SYMBOL(security_enclave_init);
> +#endif /* CONFIG_INTEL_SGX */