[03/11] LSM: Manage file security blobs
diff mbox

Message ID a19965e2-1787-a190-5648-79bb465ebcab@schaufler-ca.com
State New
Headers show

Commit Message

Casey Schaufler Aug. 29, 2017, 8:57 p.m. UTC
Subject: [PATCH 03/11] LSM: Manage file security blobs

Move the management of file security blobs from the individual
security modules to the security infrastructure. The security modules
using file blobs have been updated accordingly. Modules are required
to identify the space they need at module initialization. In some
cases a module no longer needs to supply a blob management hook, in
which case the hook has been removed.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/lsm_hooks.h           |  1 +
 security/apparmor/include/context.h |  5 +++++
 security/apparmor/include/file.h    |  2 +-
 security/apparmor/lsm.c             | 19 +++++++++--------
 security/security.c                 | 32 +++++++++++++++++++++++++++++
 security/selinux/hooks.c            | 41 +++++++++----------------------------
 security/selinux/include/objsec.h   |  5 +++++
 security/smack/smack.h              |  5 +++++
 security/smack/smack_lsm.c          | 26 ++++++++---------------
 9 files changed, 78 insertions(+), 58 deletions(-)

Comments

Stephen Smalley Aug. 31, 2017, 3:47 p.m. UTC | #1
On Tue, 2017-08-29 at 13:57 -0700, Casey Schaufler wrote:
> Subject: [PATCH 03/11] LSM: Manage file security blobs
> 
> Move the management of file security blobs from the individual
> security modules to the security infrastructure. The security modules
> using file blobs have been updated accordingly. Modules are required
> to identify the space they need at module initialization. In some
> cases a module no longer needs to supply a blob management hook, in
> which case the hook has been removed.
> 
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> ---
>  include/linux/lsm_hooks.h           |  1 +
>  security/apparmor/include/context.h |  5 +++++
>  security/apparmor/include/file.h    |  2 +-
>  security/apparmor/lsm.c             | 19 +++++++++--------
>  security/security.c                 | 32
> +++++++++++++++++++++++++++++
>  security/selinux/hooks.c            | 41 +++++++++----------------
> ------------
>  security/selinux/include/objsec.h   |  5 +++++
>  security/smack/smack.h              |  5 +++++
>  security/smack/smack_lsm.c          | 26 ++++++++---------------
>  9 files changed, 78 insertions(+), 58 deletions(-)
> 
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index 4ecb4ed572cf..0603c57726e4 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -1923,6 +1923,7 @@ struct security_hook_list {
>   */
>  struct lsm_blob_sizes {
>  	int	lbs_cred;
> +	int	lbs_file;
>  };
>  
>  /*
> diff --git a/security/apparmor/include/context.h
> b/security/apparmor/include/context.h
> index 301ab3a0dd04..c6e106a533e8 100644
> --- a/security/apparmor/include/context.h
> +++ b/security/apparmor/include/context.h
> @@ -87,6 +87,11 @@ static inline struct aa_label
> *aa_get_newest_cred_label(const struct cred *cred)
>  	return aa_get_newest_label(aa_cred_raw_label(cred));
>  }
>  
> +static inline struct aa_file_ctx *apparmor_file(const struct file
> *file)
> +{
> +	return file->f_security;
> +}
> +
>  /**
>   * __aa_task_raw_label - retrieve another task's label
>   * @task: task to query  (NOT NULL)
> diff --git a/security/apparmor/include/file.h
> b/security/apparmor/include/file.h
> index 001e40073ff9..af87b23700d7 100644
> --- a/security/apparmor/include/file.h
> +++ b/security/apparmor/include/file.h
> @@ -32,7 +32,7 @@ struct path;
>  				 AA_MAY_CHMOD | AA_MAY_CHOWN |
> AA_MAY_LOCK | \
>  				 AA_EXEC_MMAP | AA_MAY_LINK)
>  
> -#define file_ctx(X) ((struct aa_file_ctx *)(X)->f_security)
> +#define file_ctx(X) apparmor_file(X)
>  
>  /* struct aa_file_ctx - the AppArmor context the file was opened in
>   * @lock: lock to update the ctx
> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
> index 827df7012fe4..fb317cc94510 100644
> --- a/security/apparmor/lsm.c
> +++ b/security/apparmor/lsm.c
> @@ -400,21 +400,21 @@ static int apparmor_file_open(struct file
> *file, const struct cred *cred)
>  
>  static int apparmor_file_alloc_security(struct file *file)
>  {
> -	int error = 0;
> -
> -	/* freed by apparmor_file_free_security */
> +	struct aa_file_ctx *ctx = file_ctx(file);
>  	struct aa_label *label = begin_current_label_crit_section();
> -	file->f_security = aa_alloc_file_ctx(label, GFP_KERNEL);
> -	if (!file_ctx(file))
> -		error = -ENOMEM;
> -	end_current_label_crit_section(label);
>  
> -	return error;
> +	spin_lock_init(&ctx->lock);
> +	rcu_assign_pointer(ctx->label, aa_get_label(label));
> +	end_current_label_crit_section(label);
> +	return 0;
>  }
>  
>  static void apparmor_file_free_security(struct file *file)
>  {
> -	aa_free_file_ctx(file_ctx(file));
> +	struct aa_file_ctx *ctx = file_ctx(file);
> +
> +	if (ctx)
> +		aa_put_label(rcu_access_pointer(ctx->label));
>  }
>  
>  static int common_file_perm(const char *op, struct file *file, u32
> mask)
> @@ -635,6 +635,7 @@ static int apparmor_task_setrlimit(struct
> task_struct *task,
>  
>  struct lsm_blob_sizes apparmor_blob_sizes = {
>  	.lbs_cred = sizeof(struct aa_task_ctx),
> +	.lbs_file = sizeof(struct aa_file_ctx),
>  };
>  
>  static struct security_hook_list apparmor_hooks[]
> __lsm_ro_after_init = {
> diff --git a/security/security.c b/security/security.c
> index 89d43c65630c..b9346db8a2d4 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -91,6 +91,7 @@ int __init security_init(void)
>  
>  #ifdef CONFIG_SECURITY_LSM_DEBUG
>  	pr_info("LSM: cred blob size       = %d\n",
> blob_sizes.lbs_cred);
> +	pr_info("LSM: file blob size       = %d\n",
> blob_sizes.lbs_file);
>  #endif
>  
>  	return 0;
> @@ -267,6 +268,30 @@ static void __init lsm_set_size(int *need, int
> *lbs)
>  void __init security_add_blobs(struct lsm_blob_sizes *needed)
>  {
>  	lsm_set_size(&needed->lbs_cred, &blob_sizes.lbs_cred);
> +	lsm_set_size(&needed->lbs_file, &blob_sizes.lbs_file);
> +}
> +
> +/**
> + * lsm_file_alloc - allocate a composite file blob
> + * @file: the file that needs a blob
> + *
> + * Allocate the file blob for all the modules
> + *
> + * Returns 0, or -ENOMEM if memory can't be allocated.
> + */
> +int lsm_file_alloc(struct file *file)
> +{
> +#ifdef CONFIG_SECURITY_LSM_DEBUG
> +	if (file->f_security)
> +		pr_info("%s: Inbound file blob is not NULL.\n",
> __func__);
> +#endif
> +	if (blob_sizes.lbs_file == 0)
> +		return 0;
> +
> +	file->f_security = kzalloc(blob_sizes.lbs_file, GFP_KERNEL);
> +	if (file->f_security == NULL)
> +		return -ENOMEM;
> +	return 0;
>  }
>  
>  /*
> @@ -957,12 +982,19 @@ int security_file_permission(struct file *file,
> int mask)
>  
>  int security_file_alloc(struct file *file)
>  {
> +	int rc = lsm_file_alloc(file);
> +
> +	if (rc)
> +		return rc;
>  	return call_int_hook(file_alloc_security, 0, file);
>  }
>  
>  void security_file_free(struct file *file)
>  {
>  	call_void_hook(file_free_security, file);
> +
> +	kfree(file->f_security);
> +	file->f_security = NULL;
>  }
>  
>  int security_file_ioctl(struct file *file, unsigned int cmd,
> unsigned long arg)
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 3b2f028f1e86..b7909d710368 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -129,7 +129,6 @@ int selinux_enabled = 1;
>  #endif
>  
>  static struct kmem_cache *sel_inode_cache;
> -static struct kmem_cache *file_security_cache;
>  
>  /**
>   * selinux_secmark_enabled - Check to see if SECMARK is currently
> enabled
> @@ -359,27 +358,15 @@ static void inode_free_security(struct inode
> *inode)
>  
>  static int file_alloc_security(struct file *file)
>  {
> -	struct file_security_struct *fsec;
> +	struct file_security_struct *fsec = selinux_file(file);
>  	u32 sid = current_sid();
>  
> -	fsec = kmem_cache_zalloc(file_security_cache, GFP_KERNEL);
> -	if (!fsec)
> -		return -ENOMEM;
> -

NAK. See commit 63205654c0e05e5ffa1c6eef2fbef21dcabd2185 for why this
was changed from a simple kzalloc() to using its own cache; we don't
want to regress in this regard.
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Casey Schaufler Aug. 31, 2017, 3:58 p.m. UTC | #2
On 8/31/2017 8:47 AM, Stephen Smalley wrote:
> On Tue, 2017-08-29 at 13:57 -0700, Casey Schaufler wrote:
>> Subject: [PATCH 03/11] LSM: Manage file security blobs
>>
>> Move the management of file security blobs from the individual
>> security modules to the security infrastructure. The security modules
>> using file blobs have been updated accordingly. Modules are required
>> to identify the space they need at module initialization. In some
>> cases a module no longer needs to supply a blob management hook, in
>> which case the hook has been removed.
>>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

<SNIP>

>>  /**
>>   * selinux_secmark_enabled - Check to see if SECMARK is currently
>> enabled
>> @@ -359,27 +358,15 @@ static void inode_free_security(struct inode
>> *inode)
>>  
>>  static int file_alloc_security(struct file *file)
>>  {
>> -	struct file_security_struct *fsec;
>> +	struct file_security_struct *fsec = selinux_file(file);
>>  	u32 sid = current_sid();
>>  
>> -	fsec = kmem_cache_zalloc(file_security_cache, GFP_KERNEL);
>> -	if (!fsec)
>> -		return -ENOMEM;
>> -
> NAK. See commit 63205654c0e05e5ffa1c6eef2fbef21dcabd2185 for why this
> was changed from a simple kzalloc() to using its own cache; we don't
> want to regress in this regard.

I was somewhat expecting this. Is there any reason that using
kmem_cache_zalloc() in the infrastructure would not address the
issue? If this is a win for SELinux it should be a win for any
module that uses file blobs.

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Stephen Smalley Aug. 31, 2017, 6:41 p.m. UTC | #3
On Thu, 2017-08-31 at 08:58 -0700, Casey Schaufler wrote:
> On 8/31/2017 8:47 AM, Stephen Smalley wrote:
> > On Tue, 2017-08-29 at 13:57 -0700, Casey Schaufler wrote:
> > > Subject: [PATCH 03/11] LSM: Manage file security blobs
> > > 
> > > Move the management of file security blobs from the individual
> > > security modules to the security infrastructure. The security
> > > modules
> > > using file blobs have been updated accordingly. Modules are
> > > required
> > > to identify the space they need at module initialization. In some
> > > cases a module no longer needs to supply a blob management hook,
> > > in
> > > which case the hook has been removed.
> > > 
> > > Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> 
> <SNIP>
> 
> > >  /**
> > >   * selinux_secmark_enabled - Check to see if SECMARK is
> > > currently
> > > enabled
> > > @@ -359,27 +358,15 @@ static void inode_free_security(struct
> > > inode
> > > *inode)
> > >  
> > >  static int file_alloc_security(struct file *file)
> > >  {
> > > -	struct file_security_struct *fsec;
> > > +	struct file_security_struct *fsec = selinux_file(file);
> > >  	u32 sid = current_sid();
> > >  
> > > -	fsec = kmem_cache_zalloc(file_security_cache,
> > > GFP_KERNEL);
> > > -	if (!fsec)
> > > -		return -ENOMEM;
> > > -
> > 
> > NAK. See commit 63205654c0e05e5ffa1c6eef2fbef21dcabd2185 for why
> > this
> > was changed from a simple kzalloc() to using its own cache; we
> > don't
> > want to regress in this regard.
> 
> I was somewhat expecting this. Is there any reason that using
> kmem_cache_zalloc() in the infrastructure would not address the
> issue? If this is a win for SELinux it should be a win for any
> module that uses file blobs.

Whether or not it will truly be a win will depend on the size of the
file security blob for that module (or module stack).  But yes, you
should be able to do the same in the infrastructure.

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Patch
diff mbox

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 4ecb4ed572cf..0603c57726e4 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1923,6 +1923,7 @@  struct security_hook_list {
  */
 struct lsm_blob_sizes {
 	int	lbs_cred;
+	int	lbs_file;
 };
 
 /*
diff --git a/security/apparmor/include/context.h b/security/apparmor/include/context.h
index 301ab3a0dd04..c6e106a533e8 100644
--- a/security/apparmor/include/context.h
+++ b/security/apparmor/include/context.h
@@ -87,6 +87,11 @@  static inline struct aa_label *aa_get_newest_cred_label(const struct cred *cred)
 	return aa_get_newest_label(aa_cred_raw_label(cred));
 }
 
+static inline struct aa_file_ctx *apparmor_file(const struct file *file)
+{
+	return file->f_security;
+}
+
 /**
  * __aa_task_raw_label - retrieve another task's label
  * @task: task to query  (NOT NULL)
diff --git a/security/apparmor/include/file.h b/security/apparmor/include/file.h
index 001e40073ff9..af87b23700d7 100644
--- a/security/apparmor/include/file.h
+++ b/security/apparmor/include/file.h
@@ -32,7 +32,7 @@  struct path;
 				 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_LOCK | \
 				 AA_EXEC_MMAP | AA_MAY_LINK)
 
-#define file_ctx(X) ((struct aa_file_ctx *)(X)->f_security)
+#define file_ctx(X) apparmor_file(X)
 
 /* struct aa_file_ctx - the AppArmor context the file was opened in
  * @lock: lock to update the ctx
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 827df7012fe4..fb317cc94510 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -400,21 +400,21 @@  static int apparmor_file_open(struct file *file, const struct cred *cred)
 
 static int apparmor_file_alloc_security(struct file *file)
 {
-	int error = 0;
-
-	/* freed by apparmor_file_free_security */
+	struct aa_file_ctx *ctx = file_ctx(file);
 	struct aa_label *label = begin_current_label_crit_section();
-	file->f_security = aa_alloc_file_ctx(label, GFP_KERNEL);
-	if (!file_ctx(file))
-		error = -ENOMEM;
-	end_current_label_crit_section(label);
 
-	return error;
+	spin_lock_init(&ctx->lock);
+	rcu_assign_pointer(ctx->label, aa_get_label(label));
+	end_current_label_crit_section(label);
+	return 0;
 }
 
 static void apparmor_file_free_security(struct file *file)
 {
-	aa_free_file_ctx(file_ctx(file));
+	struct aa_file_ctx *ctx = file_ctx(file);
+
+	if (ctx)
+		aa_put_label(rcu_access_pointer(ctx->label));
 }
 
 static int common_file_perm(const char *op, struct file *file, u32 mask)
@@ -635,6 +635,7 @@  static int apparmor_task_setrlimit(struct task_struct *task,
 
 struct lsm_blob_sizes apparmor_blob_sizes = {
 	.lbs_cred = sizeof(struct aa_task_ctx),
+	.lbs_file = sizeof(struct aa_file_ctx),
 };
 
 static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
diff --git a/security/security.c b/security/security.c
index 89d43c65630c..b9346db8a2d4 100644
--- a/security/security.c
+++ b/security/security.c
@@ -91,6 +91,7 @@  int __init security_init(void)
 
 #ifdef CONFIG_SECURITY_LSM_DEBUG
 	pr_info("LSM: cred blob size       = %d\n", blob_sizes.lbs_cred);
+	pr_info("LSM: file blob size       = %d\n", blob_sizes.lbs_file);
 #endif
 
 	return 0;
@@ -267,6 +268,30 @@  static void __init lsm_set_size(int *need, int *lbs)
 void __init security_add_blobs(struct lsm_blob_sizes *needed)
 {
 	lsm_set_size(&needed->lbs_cred, &blob_sizes.lbs_cred);
+	lsm_set_size(&needed->lbs_file, &blob_sizes.lbs_file);
+}
+
+/**
+ * lsm_file_alloc - allocate a composite file blob
+ * @file: the file that needs a blob
+ *
+ * Allocate the file blob for all the modules
+ *
+ * Returns 0, or -ENOMEM if memory can't be allocated.
+ */
+int lsm_file_alloc(struct file *file)
+{
+#ifdef CONFIG_SECURITY_LSM_DEBUG
+	if (file->f_security)
+		pr_info("%s: Inbound file blob is not NULL.\n", __func__);
+#endif
+	if (blob_sizes.lbs_file == 0)
+		return 0;
+
+	file->f_security = kzalloc(blob_sizes.lbs_file, GFP_KERNEL);
+	if (file->f_security == NULL)
+		return -ENOMEM;
+	return 0;
 }
 
 /*
@@ -957,12 +982,19 @@  int security_file_permission(struct file *file, int mask)
 
 int security_file_alloc(struct file *file)
 {
+	int rc = lsm_file_alloc(file);
+
+	if (rc)
+		return rc;
 	return call_int_hook(file_alloc_security, 0, file);
 }
 
 void security_file_free(struct file *file)
 {
 	call_void_hook(file_free_security, file);
+
+	kfree(file->f_security);
+	file->f_security = NULL;
 }
 
 int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 3b2f028f1e86..b7909d710368 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -129,7 +129,6 @@  int selinux_enabled = 1;
 #endif
 
 static struct kmem_cache *sel_inode_cache;
-static struct kmem_cache *file_security_cache;
 
 /**
  * selinux_secmark_enabled - Check to see if SECMARK is currently enabled
@@ -359,27 +358,15 @@  static void inode_free_security(struct inode *inode)
 
 static int file_alloc_security(struct file *file)
 {
-	struct file_security_struct *fsec;
+	struct file_security_struct *fsec = selinux_file(file);
 	u32 sid = current_sid();
 
-	fsec = kmem_cache_zalloc(file_security_cache, GFP_KERNEL);
-	if (!fsec)
-		return -ENOMEM;
-
 	fsec->sid = sid;
 	fsec->fown_sid = sid;
-	file->f_security = fsec;
 
 	return 0;
 }
 
-static void file_free_security(struct file *file)
-{
-	struct file_security_struct *fsec = file->f_security;
-	file->f_security = NULL;
-	kmem_cache_free(file_security_cache, fsec);
-}
-
 static int superblock_alloc_security(struct super_block *sb)
 {
 	struct superblock_security_struct *sbsec;
@@ -1820,7 +1807,7 @@  static int file_has_perm(const struct cred *cred,
 			 struct file *file,
 			 u32 av)
 {
-	struct file_security_struct *fsec = file->f_security;
+	struct file_security_struct *fsec = selinux_file(file);
 	struct inode *inode = file_inode(file);
 	struct common_audit_data ad;
 	u32 sid = cred_sid(cred);
@@ -2140,7 +2127,7 @@  static int selinux_binder_transfer_file(struct task_struct *from,
 					struct file *file)
 {
 	u32 sid = task_sid(to);
-	struct file_security_struct *fsec = file->f_security;
+	struct file_security_struct *fsec = selinux_file(file);
 	struct dentry *dentry = file->f_path.dentry;
 	struct inode_security_struct *isec;
 	struct common_audit_data ad;
@@ -3414,7 +3401,7 @@  static int selinux_revalidate_file_permission(struct file *file, int mask)
 static int selinux_file_permission(struct file *file, int mask)
 {
 	struct inode *inode = file_inode(file);
-	struct file_security_struct *fsec = file->f_security;
+	struct file_security_struct *fsec = selinux_file(file);
 	struct inode_security_struct *isec;
 	u32 sid = current_sid();
 
@@ -3436,11 +3423,6 @@  static int selinux_file_alloc_security(struct file *file)
 	return file_alloc_security(file);
 }
 
-static void selinux_file_free_security(struct file *file)
-{
-	file_free_security(file);
-}
-
 /*
  * Check whether a task has the ioctl permission and cmd
  * operation to an inode.
@@ -3449,7 +3431,7 @@  static int ioctl_has_perm(const struct cred *cred, struct file *file,
 		u32 requested, u16 cmd)
 {
 	struct common_audit_data ad;
-	struct file_security_struct *fsec = file->f_security;
+	struct file_security_struct *fsec = selinux_file(file);
 	struct inode *inode = file_inode(file);
 	struct inode_security_struct *isec;
 	struct lsm_ioctlop_audit ioctl;
@@ -3695,7 +3677,7 @@  static void selinux_file_set_fowner(struct file *file)
 {
 	struct file_security_struct *fsec;
 
-	fsec = file->f_security;
+	fsec = selinux_file(file);
 	fsec->fown_sid = current_sid();
 }
 
@@ -3710,7 +3692,7 @@  static int selinux_file_send_sigiotask(struct task_struct *tsk,
 	/* struct fown_struct is never outside the context of a struct file */
 	file = container_of(fown, struct file, f_owner);
 
-	fsec = file->f_security;
+	fsec = selinux_file(file);
 
 	if (!signum)
 		perm = signal_to_av(SIGIO); /* as per send_sigio_to_task */
@@ -3733,7 +3715,7 @@  static int selinux_file_open(struct file *file, const struct cred *cred)
 	struct file_security_struct *fsec;
 	struct inode_security_struct *isec;
 
-	fsec = file->f_security;
+	fsec = selinux_file(file);
 	isec = inode_security(file_inode(file));
 	/*
 	 * Save inode label and policy sequence number
@@ -3863,7 +3845,7 @@  static int selinux_kernel_module_from_file(struct file *file)
 	ad.type = LSM_AUDIT_DATA_FILE;
 	ad.u.file = file;
 
-	fsec = file->f_security;
+	fsec = selinux_file(file);
 	if (sid != fsec->sid) {
 		rc = avc_has_perm(sid, fsec->sid, SECCLASS_FD, FD__USE, &ad);
 		if (rc)
@@ -6208,6 +6190,7 @@  static void selinux_ib_free_security(void *ib_sec)
 
 struct lsm_blob_sizes selinux_blob_sizes = {
 	.lbs_cred = sizeof(struct task_security_struct),
+	.lbs_file = sizeof(struct file_security_struct),
 };
 
 static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
@@ -6279,7 +6262,6 @@  static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 
 	LSM_HOOK_INIT(file_permission, selinux_file_permission),
 	LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security),
-	LSM_HOOK_INIT(file_free_security, selinux_file_free_security),
 	LSM_HOOK_INIT(file_ioctl, selinux_file_ioctl),
 	LSM_HOOK_INIT(mmap_file, selinux_mmap_file),
 	LSM_HOOK_INIT(mmap_addr, selinux_mmap_addr),
@@ -6460,9 +6442,6 @@  static __init int selinux_init(void)
 	sel_inode_cache = kmem_cache_create("selinux_inode_security",
 					    sizeof(struct inode_security_struct),
 					    0, SLAB_PANIC, NULL);
-	file_security_cache = kmem_cache_create("selinux_file_security",
-					    sizeof(struct file_security_struct),
-					    0, SLAB_PANIC, NULL);
 	avc_init();
 
 	security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks), "selinux");
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index f447b21f6be0..1f39105731ee 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -161,4 +161,9 @@  static inline struct task_security_struct *selinux_cred(const struct cred *cred)
 	return cred->security;
 }
 
+static inline struct file_security_struct *selinux_file(const struct file *file)
+{
+	return file->f_security;
+}
+
 #endif /* _SELINUX_OBJSEC_H_ */
diff --git a/security/smack/smack.h b/security/smack/smack.h
index ab1d217800e2..d14e8d17eea0 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -361,6 +361,11 @@  static inline struct task_smack *smack_cred(const struct cred *cred)
 	return cred->security;
 }
 
+static inline struct smack_known **smack_file(const struct file *file)
+{
+	return file->f_security;
+}
+
 /*
  * Is the directory transmuting?
  */
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index d67ba55f0123..c2a585cfef98 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1601,25 +1601,13 @@  static void smack_inode_getsecid(struct inode *inode, u32 *secid)
  */
 static int smack_file_alloc_security(struct file *file)
 {
-	struct smack_known *skp = smk_of_current();
+	struct smack_known **blob = smack_file(file);
 
-	file->f_security = skp;
+	*blob = smk_of_current();
 	return 0;
 }
 
 /**
- * smack_file_free_security - clear a file security blob
- * @file: the object
- *
- * The security blob for a file is a pointer to the master
- * label list, so no memory is freed.
- */
-static void smack_file_free_security(struct file *file)
-{
-	file->f_security = NULL;
-}
-
-/**
  * smack_file_ioctl - Smack check on ioctls
  * @file: the object
  * @cmd: what to do
@@ -1843,7 +1831,9 @@  static int smack_mmap_file(struct file *file,
  */
 static void smack_file_set_fowner(struct file *file)
 {
-	file->f_security = smk_of_current();
+	struct smack_known **blob = smack_file(file);
+
+	*blob = smk_of_current();
 }
 
 /**
@@ -1860,6 +1850,7 @@  static void smack_file_set_fowner(struct file *file)
 static int smack_file_send_sigiotask(struct task_struct *tsk,
 				     struct fown_struct *fown, int signum)
 {
+	struct smack_known **blob;
 	struct smack_known *skp;
 	struct smack_known *tkp = smk_of_task(smack_cred(tsk->cred));
 	struct file *file;
@@ -1872,7 +1863,8 @@  static int smack_file_send_sigiotask(struct task_struct *tsk,
 	file = container_of(fown, struct file, f_owner);
 
 	/* we don't log here as rc can be overriden */
-	skp = file->f_security;
+	blob = smack_file(file);
+	skp = *blob;
 	rc = smk_access(skp, tkp, MAY_DELIVER, NULL);
 	rc = smk_bu_note("sigiotask", skp, tkp, MAY_DELIVER, rc);
 	if (rc != 0 && has_capability(tsk, CAP_MAC_OVERRIDE))
@@ -4604,6 +4596,7 @@  static int smack_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
 
 struct lsm_blob_sizes smack_blob_sizes = {
 	.lbs_cred = sizeof(struct task_smack),
+	.lbs_file = sizeof(struct smack_known *),
 };
 
 static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
@@ -4643,7 +4636,6 @@  static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(inode_getsecid, smack_inode_getsecid),
 
 	LSM_HOOK_INIT(file_alloc_security, smack_file_alloc_security),
-	LSM_HOOK_INIT(file_free_security, smack_file_free_security),
 	LSM_HOOK_INIT(file_ioctl, smack_file_ioctl),
 	LSM_HOOK_INIT(file_lock, smack_file_lock),
 	LSM_HOOK_INIT(file_fcntl, smack_file_fcntl),