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Commit 67d7ddde authored by Al Viro's avatar Al Viro
Browse files

waitid(2): leave copyout of siginfo to syscall itself 



have kernel_waitid() collect the information needed for siginfo into
a small structure (waitid_info) passed to it; deal with copyout in
sys_waitid()/compat_sys_waitid().

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 359566fa

kernel/exit.c

+64 −104
Original line number Diff line number Diff line
@@ -996,12 +996,19 @@ SYSCALL_DEFINE1(exit_group, int, error_code) 
	return 0;

}



struct waitid_info {

	pid_t pid;

	uid_t uid;

	int status;

	int cause;

};



struct wait_opts {

	enum pid_type		wo_type;

	int			wo_flags;

	struct pid		*wo_pid;



	struct siginfo __user	*wo_info;

	struct waitid_info	*wo_info;

	int			wo_stat;

	struct rusage		*wo_rusage;
@@ -1053,8 +1060,7 @@ eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) 
static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,

				pid_t pid, uid_t uid, int why, int status)

{

	struct siginfo __user *infop;

	int retval = 0;

	struct waitid_info *infop;



	if (wo->wo_rusage)

		getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
@@ -1062,22 +1068,12 @@ static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, 
	put_task_struct(p);

	infop = wo->wo_info;

	if (infop) {

		if (!retval)

			retval = put_user(SIGCHLD, &infop->si_signo);

		if (!retval)

			retval = put_user(0, &infop->si_errno);

		if (!retval)

			retval = put_user((short)why, &infop->si_code);

		if (!retval)

			retval = put_user(pid, &infop->si_pid);

		if (!retval)

			retval = put_user(uid, &infop->si_uid);

		if (!retval)

			retval = put_user(status, &infop->si_status);

	}

	if (!retval)

		retval = pid;

	return retval;

		infop->cause = why;

		infop->pid = pid;

		infop->uid = uid;

		infop->status = status;

	}

	return pid;

}



/*
@@ -1088,10 +1084,10 @@ static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, 
 */

static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)

{

	int state, retval, status;

	int state, status;

	pid_t pid = task_pid_vnr(p);

	uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));

	struct siginfo __user *infop;

	struct waitid_info *infop;



	if (!likely(wo->wo_flags & WEXITED))

		return 0;
@@ -1186,36 +1182,22 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 


	if (wo->wo_rusage)

		getrusage(p, RUSAGE_BOTH, wo->wo_rusage);

	retval = 0;

	status = (p->signal->flags & SIGNAL_GROUP_EXIT)

		? p->signal->group_exit_code : p->exit_code;

	wo->wo_stat = status;



	infop = wo->wo_info;

	if (!retval && infop)

		retval = put_user(SIGCHLD, &infop->si_signo);

	if (!retval && infop)

		retval = put_user(0, &infop->si_errno);

	if (!retval && infop) {

		int why;



	if (infop) {

		if ((status & 0x7f) == 0) {

			why = CLD_EXITED;

			status >>= 8;

			infop->cause = CLD_EXITED;

			infop->status = status >> 8;

		} else {

			why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;

			status &= 0x7f;

		}

		retval = put_user((short)why, &infop->si_code);

		if (!retval)

			retval = put_user(status, &infop->si_status);

	}

	if (!retval && infop)

		retval = put_user(pid, &infop->si_pid);

	if (!retval && infop)

		retval = put_user(uid, &infop->si_uid);

	if (!retval)

		retval = pid;

			infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;

			infop->status = status & 0x7f;

		}

		infop->pid = pid;

		infop->uid = uid;

	}



	if (state == EXIT_TRACE) {

		write_lock_irq(&tasklist_lock);
@@ -1232,7 +1214,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 
	if (state == EXIT_DEAD)

		release_task(p);



	return retval;

	return pid;

}



static int *task_stopped_code(struct task_struct *p, bool ptrace)
@@ -1268,8 +1250,8 @@ static int *task_stopped_code(struct task_struct *p, bool ptrace) 
static int wait_task_stopped(struct wait_opts *wo,

				int ptrace, struct task_struct *p)

{

	struct siginfo __user *infop;

	int retval, exit_code, *p_code, why;

	struct waitid_info *infop;

	int exit_code, *p_code, why;

	uid_t uid = 0; /* unneeded, required by compiler */

	pid_t pid;
@@ -1320,28 +1302,19 @@ static int wait_task_stopped(struct wait_opts *wo, 


	if (wo->wo_rusage)

		getrusage(p, RUSAGE_BOTH, wo->wo_rusage);

	retval = 0;

	wo->wo_stat = (exit_code << 8) | 0x7f;



	infop = wo->wo_info;

	if (!retval && infop)

		retval = put_user(SIGCHLD, &infop->si_signo);

	if (!retval && infop)

		retval = put_user(0, &infop->si_errno);

	if (!retval && infop)

		retval = put_user((short)why, &infop->si_code);

	if (!retval && infop)

		retval = put_user(exit_code, &infop->si_status);

	if (!retval && infop)

		retval = put_user(pid, &infop->si_pid);

	if (!retval && infop)

		retval = put_user(uid, &infop->si_uid);

	if (!retval)

		retval = pid;

	if (infop) {

		infop->cause = why;

		infop->status = exit_code;

		infop->pid = pid;

		infop->uid = uid;

	}

	put_task_struct(p);



	BUG_ON(!retval);

	return retval;

	BUG_ON(!pid);

	return pid;

}



/*
@@ -1618,7 +1591,7 @@ static long do_wait(struct wait_opts *wo) 
	return retval;

}



static long kernel_waitid(int which, pid_t upid, struct siginfo __user *infop,

static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,

			  int options, struct rusage *ru)

{

	struct wait_opts wo;
@@ -1660,27 +1633,8 @@ static long kernel_waitid(int which, pid_t upid, struct siginfo __user *infop, 
	wo.wo_rusage	= ru;

	ret = do_wait(&wo);



	if (ret > 0) {

	if (ret > 0)

		ret = 0;

	} else if (infop) {

		/*

		 * For a WNOHANG return, clear out all the fields

		 * we would set so the user can easily tell the

		 * difference.

		 */

		if (!ret)

			ret = put_user(0, &infop->si_signo);

		if (!ret)

			ret = put_user(0, &infop->si_errno);

		if (!ret)

			ret = put_user(0, &infop->si_code);

		if (!ret)

			ret = put_user(0, &infop->si_pid);

		if (!ret)

			ret = put_user(0, &infop->si_uid);

		if (!ret)

			ret = put_user(0, &infop->si_status);

	}



	put_pid(pid);

	return ret;
@@ -1690,12 +1644,24 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 
		infop, int, options, struct rusage __user *, ru)

{

	struct rusage r;

	long err = kernel_waitid(which, upid, infop, options, ru ? &r : NULL);

	struct waitid_info info = {.status = 0};

	long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);



	if (!err) {

		if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))

			return -EFAULT;

	}

	if (!infop)

		return err;



	if (put_user(err ? 0 : SIGCHLD, &infop->si_signo) ||

	    put_user(0, &infop->si_errno) ||

	    put_user((short)info.cause, &infop->si_code) ||

	    put_user(info.pid, &infop->si_pid) ||

	    put_user(info.uid, &infop->si_uid) ||

	    put_user(info.status, &infop->si_status))

		err = -EFAULT;



	return err;

}
@@ -1785,33 +1751,27 @@ COMPAT_SYSCALL_DEFINE5(waitid, 
		struct compat_siginfo __user *, infop, int, options,

		struct compat_rusage __user *, uru)

{

	siginfo_t info;

	struct rusage ru;

	long ret;

	mm_segment_t old_fs = get_fs();



	memset(&info, 0, sizeof(info));



	set_fs(KERNEL_DS);

	ret = kernel_waitid(which, pid, (siginfo_t __user *)&info, options,

			 uru ? &ru : NULL);

	set_fs(old_fs);

	struct waitid_info info = {.status = 0};

	long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);



	if ((ret < 0) || (info.si_signo == 0))

		return ret;



	if (uru) {

		/* sys_waitid() overwrites everything in ru */

	if (!err && uru) {

		/* kernel_waitid() overwrites everything in ru */

		if (COMPAT_USE_64BIT_TIME)

			ret = copy_to_user(uru, &ru, sizeof(ru));

			err = copy_to_user(uru, &ru, sizeof(ru));

		else

			ret = put_compat_rusage(&ru, uru);

		if (ret)

			err = put_compat_rusage(&ru, uru);

		if (err)

			return -EFAULT;

	}



	BUG_ON(info.si_code & __SI_MASK);

	info.si_code |= __SI_CHLD;

	return copy_siginfo_to_user32(infop, &info);

	if (put_user(err ? 0 : SIGCHLD, &infop->si_signo) ||

	    put_user(0, &infop->si_errno) ||

	    put_user((short)info.cause, &infop->si_code) ||

	    put_user(info.pid, &infop->si_pid) ||

	    put_user(info.uid, &infop->si_uid) ||

	    put_user(info.status, &infop->si_status))

		err = -EFAULT;

	return err;

}

#endif