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Commit 0d094efe authored by Roland McGrath's avatar Roland McGrath Committed by Linus Torvalds
Browse files

tracehook: tracehook_tracer_task 



This adds the tracehook_tracer_task() hook to consolidate all forms of
"Who is using ptrace on me?" logic.  This is used for "TracerPid:" in
/proc and for permission checks.  We also clean up the selinux code the
called an identical accessor.

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dae33574

fs/proc/array.c

+7 −2
Original line number Diff line number Diff line
@@ -80,6 +80,7 @@ 
#include <linux/delayacct.h>

#include <linux/seq_file.h>

#include <linux/pid_namespace.h>

#include <linux/tracehook.h>



#include <asm/pgtable.h>

#include <asm/processor.h>
@@ -168,8 +169,12 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, 
	rcu_read_lock();

	ppid = pid_alive(p) ?

		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;

	tpid = pid_alive(p) && p->ptrace ?

		task_pid_nr_ns(rcu_dereference(p->parent), ns) : 0;

	tpid = 0;

	if (pid_alive(p)) {

		struct task_struct *tracer = tracehook_tracer_task(p);

		if (tracer)

			tpid = task_pid_nr_ns(tracer, ns);

	}

	seq_printf(m,

		"State:\t%s\n"

		"Tgid:\t%d\n"

fs/proc/base.c

+9 −4
Original line number Diff line number Diff line
@@ -69,6 +69,7 @@ 
#include <linux/mount.h>

#include <linux/security.h>

#include <linux/ptrace.h>

#include <linux/tracehook.h>

#include <linux/cgroup.h>

#include <linux/cpuset.h>

#include <linux/audit.h>
@@ -231,10 +232,14 @@ static int check_mem_permission(struct task_struct *task) 
	 * If current is actively ptrace'ing, and would also be

	 * permitted to freshly attach with ptrace now, permit it.

	 */

	if (task->parent == current && (task->ptrace & PT_PTRACED) &&

	    task_is_stopped_or_traced(task) &&

	    ptrace_may_access(task, PTRACE_MODE_ATTACH))

	if (task_is_stopped_or_traced(task)) {

		int match;

		rcu_read_lock();

		match = (tracehook_tracer_task(task) == current);

		rcu_read_unlock();

		if (match && ptrace_may_access(task, PTRACE_MODE_ATTACH))

			return 0;

	}



	/*

	 * Noone else is allowed.

include/linux/tracehook.h

+18 −0
Original line number Diff line number Diff line
@@ -72,6 +72,24 @@ static inline int tracehook_unsafe_exec(struct task_struct *task) 
	return unsafe;

}



/**

 * tracehook_tracer_task - return the task that is tracing the given task

 * @tsk:		task to consider

 *

 * Returns NULL if noone is tracing @task, or the &struct task_struct

 * pointer to its tracer.

 *

 * Must called under rcu_read_lock().  The pointer returned might be kept

 * live only by RCU.  During exec, this may be called with task_lock()

 * held on @task, still held from when tracehook_unsafe_exec() was called.

 */

static inline struct task_struct *tracehook_tracer_task(struct task_struct *tsk)

{

	if (task_ptrace(tsk) & PT_PTRACED)

		return rcu_dereference(tsk->parent);

	return NULL;

}



/**

 * tracehook_report_exec - a successful exec was completed

 * @fmt:		&struct linux_binfmt that performed the exec

security/selinux/hooks.c

+3 −19
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ 


#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/ptrace.h>

#include <linux/tracehook.h>

#include <linux/errno.h>

#include <linux/sched.h>

#include <linux/security.h>
@@ -1971,22 +1971,6 @@ static int selinux_vm_enough_memory(struct mm_struct *mm, long pages) 
	return __vm_enough_memory(mm, pages, cap_sys_admin);

}



/**

 * task_tracer_task - return the task that is tracing the given task

 * @task:		task to consider

 *

 * Returns NULL if noone is tracing @task, or the &struct task_struct

 * pointer to its tracer.

 *

 * Must be called under rcu_read_lock().

 */

static struct task_struct *task_tracer_task(struct task_struct *task)

{

	if (task->ptrace & PT_PTRACED)

		return rcu_dereference(task->parent);

	return NULL;

}



/* binprm security operations */



static int selinux_bprm_alloc_security(struct linux_binprm *bprm)
@@ -2238,7 +2222,7 @@ static void selinux_bprm_apply_creds(struct linux_binprm *bprm, int unsafe) 
			u32 ptsid = 0;



			rcu_read_lock();

			tracer = task_tracer_task(current);

			tracer = tracehook_tracer_task(current);

			if (likely(tracer != NULL)) {

				sec = tracer->security;

				ptsid = sec->sid;
@@ -5247,7 +5231,7 @@ static int selinux_setprocattr(struct task_struct *p, 
		   Otherwise, leave SID unchanged and fail. */

		task_lock(p);

		rcu_read_lock();

		tracer = task_tracer_task(p);

		tracer = tracehook_tracer_task(p);

		if (tracer != NULL) {

			struct task_security_struct *ptsec = tracer->security;

			u32 ptsid = ptsec->sid;