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Commit 1a2a4d06 authored by Kees Cook's avatar Kees Cook Committed by James Morris
Browse files

security: create task_free security callback 



The current LSM interface to cred_free is not sufficient for allowing
an LSM to track the life and death of a task. This patch adds the
task_free hook so that an LSM can clean up resources on task death.

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent 9e3ff386

include/linux/security.h

+9 −0
Original line number Diff line number Diff line
@@ -651,6 +651,10 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts) 
 *	manual page for definitions of the @clone_flags.

 *	@clone_flags contains the flags indicating what should be shared.

 *	Return 0 if permission is granted.

 * @task_free:

 *	@task task being freed

 *	Handle release of task-related resources. (Note that this can be called

 *	from interrupt context.)

 * @cred_alloc_blank:

 *	@cred points to the credentials.

 *	@gfp indicates the atomicity of any memory allocations.
@@ -1493,6 +1497,7 @@ struct security_operations { 
	int (*dentry_open) (struct file *file, const struct cred *cred);



	int (*task_create) (unsigned long clone_flags);

	void (*task_free) (struct task_struct *task);

	int (*cred_alloc_blank) (struct cred *cred, gfp_t gfp);

	void (*cred_free) (struct cred *cred);

	int (*cred_prepare)(struct cred *new, const struct cred *old,
@@ -1752,6 +1757,7 @@ int security_file_send_sigiotask(struct task_struct *tsk, 
int security_file_receive(struct file *file);

int security_dentry_open(struct file *file, const struct cred *cred);

int security_task_create(unsigned long clone_flags);

void security_task_free(struct task_struct *task);

int security_cred_alloc_blank(struct cred *cred, gfp_t gfp);

void security_cred_free(struct cred *cred);

int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp);
@@ -2245,6 +2251,9 @@ static inline int security_task_create(unsigned long clone_flags) 
	return 0;

}



static inline void security_task_free(struct task_struct *task)

{ }



static inline int security_cred_alloc_blank(struct cred *cred, gfp_t gfp)

{

	return 0;

kernel/fork.c

+1 −0
Original line number Diff line number Diff line
@@ -192,6 +192,7 @@ void __put_task_struct(struct task_struct *tsk) 
	WARN_ON(atomic_read(&tsk->usage));

	WARN_ON(tsk == current);



	security_task_free(tsk);

	exit_creds(tsk);

	delayacct_tsk_free(tsk);

	put_signal_struct(tsk->signal);

security/capability.c

+5 −0
Original line number Diff line number Diff line
@@ -358,6 +358,10 @@ static int cap_task_create(unsigned long clone_flags) 
	return 0;

}



static void cap_task_free(struct task_struct *task)

{

}



static int cap_cred_alloc_blank(struct cred *cred, gfp_t gfp)

{

	return 0;
@@ -954,6 +958,7 @@ void __init security_fixup_ops(struct security_operations *ops) 
	set_to_cap_if_null(ops, file_receive);

	set_to_cap_if_null(ops, dentry_open);

	set_to_cap_if_null(ops, task_create);

	set_to_cap_if_null(ops, task_free);

	set_to_cap_if_null(ops, cred_alloc_blank);

	set_to_cap_if_null(ops, cred_free);

	set_to_cap_if_null(ops, cred_prepare);

security/security.c

+5 −0
Original line number Diff line number Diff line
@@ -729,6 +729,11 @@ int security_task_create(unsigned long clone_flags) 
	return security_ops->task_create(clone_flags);

}



void security_task_free(struct task_struct *task)

{

	security_ops->task_free(task);

}



int security_cred_alloc_blank(struct cred *cred, gfp_t gfp)

{

	return security_ops->cred_alloc_blank(cred, gfp);