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Commit f6ec29a4 authored by KaiGai Kohei's avatar KaiGai Kohei Committed by Linus Torvalds
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[PATCH] pacct: avoidance to refer the last thread as a representation of the process 

When pacct facility generate an 'ac_flag' field in accounting record, it
refers a task_struct of the thread which died last in the process.  But any
other task_structs are ignored.

Therefore, pacct facility drops ASU flag even if root-privilege operations are
used by any other threads except the last one.  In addition, AFORK flag is
always set when the thread of group-leader didn't die last, although this
process has called execve() after fork().

We have a same matter in ac_exitcode.  The recorded ac_exitcode is an exit
code of the last thread in the process.  There is a possibility this exitcode
is not the group leader's one.
parent 0e464814

include/linux/acct.h

+4 −4
Original line number Diff line number Diff line
@@ -122,16 +122,16 @@ struct super_block; 
extern void acct_auto_close_mnt(struct vfsmount *m);

extern void acct_auto_close(struct super_block *sb);

extern void acct_init_pacct(struct pacct_struct *pacct);

extern void acct_collect();

extern void acct_process(long exitcode);

extern void acct_collect(long exitcode, int group_dead);

extern void acct_process(void);

extern void acct_update_integrals(struct task_struct *tsk);

extern void acct_clear_integrals(struct task_struct *tsk);

#else

#define acct_auto_close_mnt(x)	do { } while (0)

#define acct_auto_close(x)	do { } while (0)

#define acct_init_pacct(x)	do { } while (0)

#define acct_collect()		do { } while (0)

#define acct_process(x)		do { } while (0)

#define acct_collect(x,y)	do { } while (0)

#define acct_process()		do { } while (0)

#define acct_update_integrals(x)		do { } while (0)

#define acct_clear_integrals(task)	do { } while (0)

#endif

include/linux/sched.h

+2 −0
Original line number Diff line number Diff line
@@ -359,6 +359,8 @@ struct sighand_struct { 
};



struct pacct_struct {

	int			ac_flag;

	long			ac_exitcode;

	unsigned long		ac_mem;

};

kernel/acct.c

+24 −18
Original line number Diff line number Diff line
@@ -75,7 +75,7 @@ int acct_parm[3] = {4, 2, 30}; 
/*

 * External references and all of the globals.

 */

static void do_acct_process(long, struct file *);

static void do_acct_process(struct file *);



/*

 * This structure is used so that all the data protected by lock
@@ -196,7 +196,7 @@ static void acct_file_reopen(struct file *file) 
	if (old_acct) {

		mnt_unpin(old_acct->f_vfsmnt);

		spin_unlock(&acct_globals.lock);

		do_acct_process(0, old_acct);

		do_acct_process(old_acct);

		filp_close(old_acct, NULL);

		spin_lock(&acct_globals.lock);

	}
@@ -419,7 +419,7 @@ static u32 encode_float(u64 value) 
/*

 *  do_acct_process does all actual work. Caller holds the reference to file.

 */

static void do_acct_process(long exitcode, struct file *file)

static void do_acct_process(struct file *file)

{

	struct pacct_struct *pacct = &current->signal->pacct;

	acct_t ac;
@@ -496,17 +496,10 @@ static void do_acct_process(long exitcode, struct file *file) 
		old_encode_dev(tty_devnum(current->signal->tty)) : 0;

	read_unlock(&tasklist_lock);



	ac.ac_flag = 0;

	if (current->flags & PF_FORKNOEXEC)

		ac.ac_flag |= AFORK;

	if (current->flags & PF_SUPERPRIV)

		ac.ac_flag |= ASU;

	if (current->flags & PF_DUMPCORE)

		ac.ac_flag |= ACORE;

	if (current->flags & PF_SIGNALED)

		ac.ac_flag |= AXSIG;

	spin_lock(&current->sighand->siglock);

	ac.ac_flag = pacct->ac_flag;

	ac.ac_mem = encode_comp_t(pacct->ac_mem);

	ac.ac_exitcode = pacct->ac_exitcode;

	spin_unlock(&current->sighand->siglock);

	ac.ac_io = encode_comp_t(0 /* current->io_usage */);	/* %% */

	ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
@@ -515,7 +508,6 @@ static void do_acct_process(long exitcode, struct file *file) 
	ac.ac_majflt = encode_comp_t(current->signal->maj_flt +

				     current->maj_flt);

	ac.ac_swaps = encode_comp_t(0);

	ac.ac_exitcode = exitcode;



	/*

         * Kernel segment override to datasegment and write it
@@ -544,13 +536,15 @@ void acct_init_pacct(struct pacct_struct *pacct) 


/**

 * acct_collect - collect accounting information into pacct_struct

 * @exitcode: task exit code

 * @group_dead: not 0, if this thread is the last one in the process.

 */

void acct_collect(void)

void acct_collect(long exitcode, int group_dead)

{

	struct pacct_struct *pacct = &current->signal->pacct;

	unsigned long vsize = 0;



	if (current->mm) {

	if (group_dead && current->mm) {

		struct vm_area_struct *vma;

		down_read(&current->mm->mmap_sem);

		vma = current->mm->mmap;
@@ -562,7 +556,19 @@ void acct_collect(void) 
	}



	spin_lock(&current->sighand->siglock);

	if (group_dead)

		pacct->ac_mem = vsize / 1024;

	if (thread_group_leader(current)) {

		pacct->ac_exitcode = exitcode;

		if (current->flags & PF_FORKNOEXEC)

			pacct->ac_flag |= AFORK;

	}

	if (current->flags & PF_SUPERPRIV)

		pacct->ac_flag |= ASU;

	if (current->flags & PF_DUMPCORE)

		pacct->ac_flag |= ACORE;

	if (current->flags & PF_SIGNALED)

		pacct->ac_flag |= AXSIG;

	spin_unlock(&current->sighand->siglock);

}
@@ -572,7 +578,7 @@ void acct_collect(void) 
 *

 * handles process accounting for an exiting task

 */

void acct_process(long exitcode)

void acct_process()

{

	struct file *file = NULL;
@@ -591,7 +597,7 @@ void acct_process(long exitcode) 
	get_file(file);

	spin_unlock(&acct_globals.lock);



	do_acct_process(exitcode, file);

	do_acct_process(file);

	fput(file);

}

kernel/exit.c

+2 −2
Original line number Diff line number Diff line
@@ -894,8 +894,8 @@ fastcall NORET_TYPE void do_exit(long code) 
	if (group_dead) {

 		hrtimer_cancel(&tsk->signal->real_timer);

		exit_itimers(tsk->signal);

		acct_collect();

	}

	acct_collect(code, group_dead);

	if (unlikely(tsk->robust_list))

		exit_robust_list(tsk);

#if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
@@ -907,7 +907,7 @@ fastcall NORET_TYPE void do_exit(long code) 
	exit_mm(tsk);



	if (group_dead)

		acct_process(code);

		acct_process();

	exit_sem(tsk);

	__exit_files(tsk);

	__exit_fs(tsk);