[GitHub/LineageOS/android_kernel_samsung_universal7580.git] / fs / signalfd.c

/*
 *  fs/signalfd.c
 *
 *  Copyright (C) 2003  Linus Torvalds
 *
 *  Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>
 *      Changed ->read() to return a siginfo strcture instead of signal number.
 *      Fixed locking in ->poll().
 *      Added sighand-detach notification.
 *      Added fd re-use in sys_signalfd() syscall.
 *      Now using anonymous inode source.
 *      Thanks to Oleg Nesterov for useful code review and suggestions.
 *      More comments and suggestions from Arnd Bergmann.
 *  Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
 *      Retrieve multiple signals with one read() call
 *  Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
 *      Attach to the sighand only during read() and poll().
 */

#include <linux/file.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/list.h>
#include <linux/anon_inodes.h>
#include <linux/signalfd.h>
#include <linux/syscalls.h>

void signalfd_cleanup(struct sighand_struct *sighand)
{
	wait_queue_head_t *wqh = &sighand->signalfd_wqh;

	if (likely(!waitqueue_active(wqh)))
		return;

	/* wait_queue_t->func(POLLFREE) should do remove_wait_queue() */
	wake_up_poll(wqh, POLLHUP | POLLFREE);
}

struct signalfd_ctx {
	sigset_t sigmask;
};

static int signalfd_release(struct inode *inode, struct file *file)
{
	kfree(file->private_data);
	return 0;
}

static unsigned int signalfd_poll(struct file *file, poll_table *wait)
{
	struct signalfd_ctx *ctx = file->private_data;
	unsigned int events = 0;

	poll_wait(file, &current->sighand->signalfd_wqh, wait);

	spin_lock_irq(&current->sighand->siglock);
	if (next_signal(&current->pending, &ctx->sigmask) ||
	    next_signal(&current->signal->shared_pending,
			&ctx->sigmask))
		events |= POLLIN;
	spin_unlock_irq(&current->sighand->siglock);

	return events;
}

/*
 * Copied from copy_siginfo_to_user() in kernel/signal.c
 */
static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
			     siginfo_t const *kinfo)
{
	long err;

	BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);

	/*
	 * Unused members should be zero ...
	 */
	err = __clear_user(uinfo, sizeof(*uinfo));

	/*
	 * If you change siginfo_t structure, please be sure
	 * this code is fixed accordingly.
	 */
	err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
	err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
	err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
	switch (kinfo->si_code & __SI_MASK) {
	case __SI_KILL:
		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
		break;
	case __SI_TIMER:
		 err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
		 err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
		 err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
		 err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
		break;
	case __SI_POLL:
		err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
		err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
		break;
	case __SI_FAULT:
		err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
#ifdef __ARCH_SI_TRAPNO
		err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
#endif
#ifdef BUS_MCEERR_AO
		/* 
		 * Other callers might not initialize the si_lsb field,
		 * so check explicitly for the right codes here.
		 */
		if (kinfo->si_code == BUS_MCEERR_AR ||
		    kinfo->si_code == BUS_MCEERR_AO)
			err |= __put_user((short) kinfo->si_addr_lsb,
					  &uinfo->ssi_addr_lsb);
#endif
		break;
	case __SI_CHLD:
		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
		err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
		err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
		err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
		break;
	case __SI_RT: /* This is not generated by the kernel as of now. */
	case __SI_MESGQ: /* But this is */
		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
		err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
		err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
		break;
	default:
		/*
		 * This case catches also the signals queued by sigqueue().
		 */
		err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
		err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
		err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
		err |= __put_user(kinfo->si_int, &uinfo->ssi_int);
		break;
	}

	return err ? -EFAULT: sizeof(*uinfo);
}

static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
				int nonblock)
{
	ssize_t ret;
	DECLARE_WAITQUEUE(wait, current);

	spin_lock_irq(&current->sighand->siglock);
	ret = dequeue_signal(current, &ctx->sigmask, info);
	switch (ret) {
	case 0:
		if (!nonblock)
			break;
		ret = -EAGAIN;
	default:
		spin_unlock_irq(&current->sighand->siglock);
		return ret;
	}

	add_wait_queue(&current->sighand->signalfd_wqh, &wait);
	for (;;) {
		set_current_state(TASK_INTERRUPTIBLE);
		ret = dequeue_signal(current, &ctx->sigmask, info);
		if (ret != 0)
			break;
		if (signal_pending(current)) {
			ret = -ERESTARTSYS;
			break;
		}
		spin_unlock_irq(&current->sighand->siglock);
		schedule();
		spin_lock_irq(&current->sighand->siglock);
	}
	spin_unlock_irq(&current->sighand->siglock);

	remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
	__set_current_state(TASK_RUNNING);

	return ret;
}

/*
 * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
 * error code. The "count" parameter must be at least the size of a
 * "struct signalfd_siginfo".
 */
static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
			     loff_t *ppos)
{
	struct signalfd_ctx *ctx = file->private_data;
	struct signalfd_siginfo __user *siginfo;
	int nonblock = file->f_flags & O_NONBLOCK;
	ssize_t ret, total = 0;
	siginfo_t info;

	count /= sizeof(struct signalfd_siginfo);
	if (!count)
		return -EINVAL;

	siginfo = (struct signalfd_siginfo __user *) buf;
	do {
		ret = signalfd_dequeue(ctx, &info, nonblock);
		if (unlikely(ret <= 0))
			break;
		ret = signalfd_copyinfo(siginfo, &info);
		if (ret < 0)
			break;
		siginfo++;
		total += ret;
		nonblock = 1;
	} while (--count);

	return total ? total: ret;
}

static const struct file_operations signalfd_fops = {
	.release	= signalfd_release,
	.poll		= signalfd_poll,
	.read		= signalfd_read,
	.llseek		= noop_llseek,
};

SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
		size_t, sizemask, int, flags)
{
	sigset_t sigmask;
	struct signalfd_ctx *ctx;

	/* Check the SFD_* constants for consistency.  */
	BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
	BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);

	if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
		return -EINVAL;

	if (sizemask != sizeof(sigset_t) ||
	    copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
		return -EINVAL;
	sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
	signotset(&sigmask);

	if (ufd == -1) {
		ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
		if (!ctx)
			return -ENOMEM;

		ctx->sigmask = sigmask;

		/*
		 * When we call this, the initialization must be complete, since
		 * anon_inode_getfd() will install the fd.
		 */
		ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
				       O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
		if (ufd < 0)
			kfree(ctx);
	} else {
		struct file *file = fget(ufd);
		if (!file)
			return -EBADF;
		ctx = file->private_data;
		if (file->f_op != &signalfd_fops) {
			fput(file);
			return -EINVAL;
		}
		spin_lock_irq(&current->sighand->siglock);
		ctx->sigmask = sigmask;
		spin_unlock_irq(&current->sighand->siglock);

		wake_up(&current->sighand->signalfd_wqh);
		fput(file);
	}

	return ufd;
}

SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
		size_t, sizemask)
{
	return sys_signalfd4(ufd, user_mask, sizemask, 0);
}
Commit	Line	Data
fba2afaa DL	1	/*
	2	* fs/signalfd.c
	3	*
	4	* Copyright (C) 2003 Linus Torvalds
	5	*
	6	* Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>
	7	* Changed ->read() to return a siginfo strcture instead of signal number.
	8	* Fixed locking in ->poll().
	9	* Added sighand-detach notification.
	10	* Added fd re-use in sys_signalfd() syscall.
	11	* Now using anonymous inode source.
	12	* Thanks to Oleg Nesterov for useful code review and suggestions.
	13	* More comments and suggestions from Arnd Bergmann.
b8fceee1	14	* Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
b3762bfc	15	* Retrieve multiple signals with one read() call
b8fceee1 DL	16	* Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
b8fceee1 DL	17	* Attach to the sighand only during read() and poll().
fba2afaa DL	18	*/
	19
	20	#include <linux/file.h>
	21	#include <linux/poll.h>
	22	#include <linux/init.h>
	23	#include <linux/fs.h>
	24	#include <linux/sched.h>
5a0e3ad6	25	#include <linux/slab.h>
fba2afaa DL	26	#include <linux/kernel.h>
	27	#include <linux/signal.h>
	28	#include <linux/list.h>
	29	#include <linux/anon_inodes.h>
	30	#include <linux/signalfd.h>
7ec37dfd	31	#include <linux/syscalls.h>
fba2afaa	32
d80e731e ON	33	void signalfd_cleanup(struct sighand_struct *sighand)
	34	{
	35	wait_queue_head_t *wqh = &sighand->signalfd_wqh;
	36
	37	if (likely(!waitqueue_active(wqh)))
	38	return;
	39
	40	/* wait_queue_t->func(POLLFREE) should do remove_wait_queue() */
	41	wake_up_poll(wqh, POLLHUP \| POLLFREE);
	42	}
	43
fba2afaa	44	struct signalfd_ctx {
fba2afaa	45	sigset_t sigmask;
fba2afaa DL	46	};
fba2afaa DL	47
fba2afaa DL	48	static int signalfd_release(struct inode inode, struct file file)
fba2afaa DL	49	{
b8fceee1	50	kfree(file->private_data);
fba2afaa DL	51	return 0;
	52	}
	53
	54	static unsigned int signalfd_poll(struct file file, poll_table wait)
	55	{
	56	struct signalfd_ctx *ctx = file->private_data;
	57	unsigned int events = 0;
fba2afaa	58
b8fceee1	59	poll_wait(file, &current->sighand->signalfd_wqh, wait);
fba2afaa	60
b8fceee1 DL	61	spin_lock_irq(&current->sighand->siglock);
	62	if (next_signal(&current->pending, &ctx->sigmask) \|\|
	63	next_signal(&current->signal->shared_pending,
	64	&ctx->sigmask))
fba2afaa	65	events \|= POLLIN;
b8fceee1	66	spin_unlock_irq(&current->sighand->siglock);
fba2afaa DL	67
	68	return events;
	69	}
	70
	71	/*
	72	* Copied from copy_siginfo_to_user() in kernel/signal.c
	73	*/
	74	static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
	75	siginfo_t const *kinfo)
	76	{
	77	long err;
	78
	79	BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
	80
	81	/*
14e4a0f2	82	* Unused members should be zero ...
fba2afaa DL	83	*/
	84	err = __clear_user(uinfo, sizeof(*uinfo));
	85
	86	/*
	87	* If you change siginfo_t structure, please be sure
	88	* this code is fixed accordingly.
	89	*/
96358de6 DL	90	err \|= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
	91	err \|= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
	92	err \|= __put_user((short) kinfo->si_code, &uinfo->ssi_code);
fba2afaa DL	93	switch (kinfo->si_code & __SI_MASK) {
fba2afaa DL	94	case __SI_KILL:
96358de6 DL	95	err \|= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
96358de6 DL	96	err \|= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
fba2afaa DL	97	break;
fba2afaa DL	98	case __SI_TIMER:
96358de6 DL	99	err \|= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
	100	err \|= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
	101	err \|= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
a2a20c41	102	err \|= __put_user(kinfo->si_int, &uinfo->ssi_int);
fba2afaa DL	103	break;
fba2afaa DL	104	case __SI_POLL:
96358de6 DL	105	err \|= __put_user(kinfo->si_band, &uinfo->ssi_band);
96358de6 DL	106	err \|= __put_user(kinfo->si_fd, &uinfo->ssi_fd);
fba2afaa DL	107	break;
fba2afaa DL	108	case __SI_FAULT:
96358de6	109	err \|= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);
fba2afaa	110	#ifdef __ARCH_SI_TRAPNO
96358de6	111	err \|= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);
b8aeec34 HS	112	#endif
	113	#ifdef BUS_MCEERR_AO
	114	/*
	115	* Other callers might not initialize the si_lsb field,
	116	* so check explicitly for the right codes here.
	117	*/
	118	if (kinfo->si_code == BUS_MCEERR_AR \|\|
	119	kinfo->si_code == BUS_MCEERR_AO)
	120	err \|= __put_user((short) kinfo->si_addr_lsb,
	121	&uinfo->ssi_addr_lsb);
fba2afaa DL	122	#endif
	123	break;
	124	case __SI_CHLD:
96358de6 DL	125	err \|= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
	126	err \|= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
	127	err \|= __put_user(kinfo->si_status, &uinfo->ssi_status);
	128	err \|= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
	129	err \|= __put_user(kinfo->si_stime, &uinfo->ssi_stime);
fba2afaa DL	130	break;
	131	case __SI_RT: /* This is not generated by the kernel as of now. */
	132	case __SI_MESGQ: /* But this is */
96358de6 DL	133	err \|= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
	134	err \|= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
	135	err \|= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
a2a20c41	136	err \|= __put_user(kinfo->si_int, &uinfo->ssi_int);
fba2afaa	137	break;
0859ab59 DL	138	default:
	139	/*
	140	* This case catches also the signals queued by sigqueue().
	141	*/
96358de6 DL	142	err \|= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
96358de6 DL	143	err \|= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
0859ab59 DL	144	err \|= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);
0859ab59 DL	145	err \|= __put_user(kinfo->si_int, &uinfo->ssi_int);
fba2afaa DL	146	break;
	147	}
	148
	149	return err ? -EFAULT: sizeof(*uinfo);
	150	}
	151
b3762bfc DA	152	static ssize_t signalfd_dequeue(struct signalfd_ctx ctx, siginfo_t info,
	153	int nonblock)
	154	{
	155	ssize_t ret;
b3762bfc DA	156	DECLARE_WAITQUEUE(wait, current);
b3762bfc DA	157
b8fceee1 DL	158	spin_lock_irq(&current->sighand->siglock);
b8fceee1 DL	159	ret = dequeue_signal(current, &ctx->sigmask, info);
b3762bfc DA	160	switch (ret) {
	161	case 0:
	162	if (!nonblock)
	163	break;
	164	ret = -EAGAIN;
	165	default:
b8fceee1	166	spin_unlock_irq(&current->sighand->siglock);
b3762bfc DA	167	return ret;
	168	}
	169
b8fceee1	170	add_wait_queue(&current->sighand->signalfd_wqh, &wait);
b3762bfc DA	171	for (;;) {
b3762bfc DA	172	set_current_state(TASK_INTERRUPTIBLE);
b8fceee1	173	ret = dequeue_signal(current, &ctx->sigmask, info);
b3762bfc DA	174	if (ret != 0)
	175	break;
	176	if (signal_pending(current)) {
	177	ret = -ERESTARTSYS;
	178	break;
	179	}
b8fceee1	180	spin_unlock_irq(&current->sighand->siglock);
b3762bfc	181	schedule();
b8fceee1	182	spin_lock_irq(&current->sighand->siglock);
b3762bfc	183	}
b8fceee1	184	spin_unlock_irq(&current->sighand->siglock);
b3762bfc	185
b8fceee1	186	remove_wait_queue(&current->sighand->signalfd_wqh, &wait);
b3762bfc DA	187	__set_current_state(TASK_RUNNING);
	188
	189	return ret;
	190	}
	191
fba2afaa	192	/*
b8fceee1 DL	193	* Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
	194	* error code. The "count" parameter must be at least the size of a
	195	* "struct signalfd_siginfo".
fba2afaa DL	196	*/
	197	static ssize_t signalfd_read(struct file file, char __user buf, size_t count,
	198	loff_t *ppos)
	199	{
	200	struct signalfd_ctx *ctx = file->private_data;
b3762bfc DA	201	struct signalfd_siginfo __user *siginfo;
	202	int nonblock = file->f_flags & O_NONBLOCK;
	203	ssize_t ret, total = 0;
fba2afaa	204	siginfo_t info;
fba2afaa	205
b3762bfc DA	206	count /= sizeof(struct signalfd_siginfo);
b3762bfc DA	207	if (!count)
fba2afaa	208	return -EINVAL;
fba2afaa	209
b3762bfc	210	siginfo = (struct signalfd_siginfo __user *) buf;
b3762bfc DA	211	do {
	212	ret = signalfd_dequeue(ctx, &info, nonblock);
	213	if (unlikely(ret <= 0))
	214	break;
	215	ret = signalfd_copyinfo(siginfo, &info);
	216	if (ret < 0)
	217	break;
	218	siginfo++;
	219	total += ret;
	220	nonblock = 1;
	221	} while (--count);
	222
b8fceee1	223	return total ? total: ret;
fba2afaa DL	224	}
	225
	226	static const struct file_operations signalfd_fops = {
	227	.release = signalfd_release,
	228	.poll = signalfd_poll,
	229	.read = signalfd_read,
6038f373	230	.llseek = noop_llseek,
fba2afaa DL	231	};
fba2afaa DL	232
836f92ad HC	233	SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
836f92ad HC	234	size_t, sizemask, int, flags)
fba2afaa	235	{
fba2afaa DL	236	sigset_t sigmask;
fba2afaa DL	237	struct signalfd_ctx *ctx;
fba2afaa	238
e38b36f3 UD	239	/* Check the SFD_* constants for consistency. */
	240	BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
	241	BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
	242
5fb5e049	243	if (flags & ~(SFD_CLOEXEC \| SFD_NONBLOCK))
9deb27ba UD	244	return -EINVAL;
9deb27ba UD	245
fba2afaa DL	246	if (sizemask != sizeof(sigset_t) \|\|
fba2afaa DL	247	copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
f50cadaa	248	return -EINVAL;
fba2afaa DL	249	sigdelsetmask(&sigmask, sigmask(SIGKILL) \| sigmask(SIGSTOP));
	250	signotset(&sigmask);
	251
	252	if (ufd == -1) {
	253	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
	254	if (!ctx)
	255	return -ENOMEM;
	256
fba2afaa	257	ctx->sigmask = sigmask;
fba2afaa DL	258
	259	/*
	260	* When we call this, the initialization must be complete, since
	261	* anon_inode_getfd() will install the fd.
	262	*/
7d9dbca3	263	ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
628ff7c1	264	O_RDWR \| (flags & (O_CLOEXEC \| O_NONBLOCK)));
2030a42c AV	265	if (ufd < 0)
2030a42c AV	266	kfree(ctx);
fba2afaa	267	} else {
2030a42c	268	struct file *file = fget(ufd);
fba2afaa DL	269	if (!file)
	270	return -EBADF;
	271	ctx = file->private_data;
	272	if (file->f_op != &signalfd_fops) {
	273	fput(file);
	274	return -EINVAL;
	275	}
b8fceee1 DL	276	spin_lock_irq(&current->sighand->siglock);
	277	ctx->sigmask = sigmask;
	278	spin_unlock_irq(&current->sighand->siglock);
	279
	280	wake_up(&current->sighand->signalfd_wqh);
fba2afaa DL	281	fput(file);
	282	}
	283
	284	return ufd;
fba2afaa	285	}
9deb27ba	286
836f92ad HC	287	SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
836f92ad HC	288	size_t, sizemask)
9deb27ba UD	289	{
	290	return sys_signalfd4(ufd, user_mask, sizemask, 0);
	291	}