Merge branch 'tty-splice' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux into tty-next

Fixes both the "splice/sendfile to a tty" and "splice/sendfile from a
tty" regression from 5.10.

* 'tty-splice' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux:
  tty: teach the n_tty ICANON case about the new "cookie continuations" too
  tty: teach n_tty line discipline about the new "cookie continuations"
  tty: clean up legacy leftovers from n_tty line discipline
  tty: implement read_iter
  tty: convert tty_ldisc_ops 'read()' function to take a kernel pointer
  tty: implement write_iter

1 files changed, 96 insertions, 34 deletions

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index f19a34a93fe5..c7763743a3d6 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -142,10 +142,9 @@ LIST_HEAD(tty_drivers);			/* linked list of tty drivers */
 /* Mutex to protect creating and releasing a tty */
 DEFINE_MUTEX(tty_mutex);
 
-static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
-static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
-ssize_t redirected_tty_write(struct file *, const char __user *,
-							size_t, loff_t *);
+static ssize_t tty_read(struct kiocb *, struct iov_iter *);
+static ssize_t tty_write(struct kiocb *, struct iov_iter *);
+ssize_t redirected_tty_write(struct kiocb *, struct iov_iter *);
 static __poll_t tty_poll(struct file *, poll_table *);
 static int tty_open(struct inode *, struct file *);
 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
@@ -477,8 +476,10 @@ static void tty_show_fdinfo(struct seq_file *m, struct file *file)
 
 static const struct file_operations tty_fops = {
 	.llseek		= no_llseek,
-	.read		= tty_read,
-	.write		= tty_write,
+	.read_iter	= tty_read,
+	.write_iter	= tty_write,
+	.splice_read	= generic_file_splice_read,
+	.splice_write	= iter_file_splice_write,
 	.poll		= tty_poll,
 	.unlocked_ioctl	= tty_ioctl,
 	.compat_ioctl	= tty_compat_ioctl,
@@ -490,8 +491,10 @@ static const struct file_operations tty_fops = {
 
 static const struct file_operations console_fops = {
 	.llseek		= no_llseek,
-	.read		= tty_read,
-	.write		= redirected_tty_write,
+	.read_iter	= tty_read,
+	.write_iter	= redirected_tty_write,
+	.splice_read	= generic_file_splice_read,
+	.splice_write	= iter_file_splice_write,
 	.poll		= tty_poll,
 	.unlocked_ioctl	= tty_ioctl,
 	.compat_ioctl	= tty_compat_ioctl,
@@ -623,9 +626,9 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session)
 	/* This breaks for file handles being sent over AF_UNIX sockets ? */
 	list_for_each_entry(priv, &tty->tty_files, list) {
 		filp = priv->file;
-		if (filp->f_op->write == redirected_tty_write)
+		if (filp->f_op->write_iter == redirected_tty_write)
 			cons_filp = filp;
-		if (filp->f_op->write != tty_write)
+		if (filp->f_op->write_iter != tty_write)
 			continue;
 		closecount++;
 		__tty_fasync(-1, filp, 0);	/* can't block */
@@ -848,6 +851,65 @@ static void tty_update_time(struct timespec64 *time)
 		time->tv_sec = sec;
 }
 
+/*
+ * Iterate on the ldisc ->read() function until we've gotten all
+ * the data the ldisc has for us.
+ *
+ * The "cookie" is something that the ldisc read function can fill
+ * in to let us know that there is more data to be had.
+ *
+ * We promise to continue to call the ldisc until it stops returning
+ * data or clears the cookie. The cookie may be something that the
+ * ldisc maintains state for and needs to free.
+ */
+static int iterate_tty_read(struct tty_ldisc *ld, struct tty_struct *tty,
+		struct file *file, struct iov_iter *to)
+{
+	int retval = 0;
+	void *cookie = NULL;
+	unsigned long offset = 0;
+	char kernel_buf[64];
+	size_t count = iov_iter_count(to);
+
+	do {
+		int size, copied;
+
+		size = count > sizeof(kernel_buf) ? sizeof(kernel_buf) : count;
+		size = ld->ops->read(tty, file, kernel_buf, size, &cookie, offset);
+		if (!size)
+			break;
+
+		/*
+		 * A ldisc read error return will override any previously copied
+		 * data (eg -EOVERFLOW from HDLC)
+		 */
+		if (size < 0) {
+			memzero_explicit(kernel_buf, sizeof(kernel_buf));
+			return size;
+		}
+
+		copied = copy_to_iter(kernel_buf, size, to);
+		offset += copied;
+		count -= copied;
+
+		/*
+		 * If the user copy failed, we still need to do another ->read()
+		 * call if we had a cookie to let the ldisc clear up.
+		 *
+		 * But make sure size is zeroed.
+		 */
+		if (unlikely(copied != size)) {
+			count = 0;
+			retval = -EFAULT;
+		}
+	} while (cookie);
+
+	/* We always clear tty buffer in case they contained passwords */
+	memzero_explicit(kernel_buf, sizeof(kernel_buf));
+	return offset ? offset : retval;
+}
+
+
 /**
  *	tty_read	-	read method for tty device files
  *	@file: pointer to tty file
@@ -863,10 +925,10 @@ static void tty_update_time(struct timespec64 *time)
  *	read calls may be outstanding in parallel.
  */
 
-static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
-			loff_t *ppos)
+static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
 {
 	int i;
+	struct file *file = iocb->ki_filp;
 	struct inode *inode = file_inode(file);
 	struct tty_struct *tty = file_tty(file);
 	struct tty_ldisc *ld;
@@ -879,12 +941,9 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
 	/* We want to wait for the line discipline to sort out in this
 	   situation */
 	ld = tty_ldisc_ref_wait(tty);
-	if (!ld)
-		return hung_up_tty_read(file, buf, count, ppos);
-	if (ld->ops->read)
-		i = ld->ops->read(tty, file, buf, count);
-	else
-		i = -EIO;
+	i = -EIO;
+	if (ld && ld->ops->read)
+		i = iterate_tty_read(ld, tty, file, to);
 	tty_ldisc_deref(ld);
 
 	if (i > 0)
@@ -918,9 +977,9 @@ static inline ssize_t do_tty_write(
 	ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
 	struct tty_struct *tty,
 	struct file *file,
-	const char __user *buf,
-	size_t count)
+	struct iov_iter *from)
 {
+	size_t count = iov_iter_count(from);
 	ssize_t ret, written = 0;
 	unsigned int chunk;
 
@@ -972,14 +1031,20 @@ static inline ssize_t do_tty_write(
 		size_t size = count;
 		if (size > chunk)
 			size = chunk;
+
 		ret = -EFAULT;
-		if (copy_from_user(tty->write_buf, buf, size))
+		if (copy_from_iter(tty->write_buf, size, from) != size)
 			break;
+
 		ret = write(tty, file, tty->write_buf, size);
 		if (ret <= 0)
 			break;
+
+		/* FIXME! Have Al check this! */
+		if (ret != size)
+			iov_iter_revert(from, size-ret);
+
 		written += ret;
-		buf += ret;
 		count -= ret;
 		if (!count)
 			break;
@@ -1039,9 +1104,9 @@ void tty_write_message(struct tty_struct *tty, char *msg)
  *	write method will not be invoked in parallel for each device.
  */
 
-static ssize_t tty_write(struct file *file, const char __user *buf,
-						size_t count, loff_t *ppos)
+static ssize_t tty_write(struct kiocb *iocb, struct iov_iter *from)
 {
+	struct file *file = iocb->ki_filp;
 	struct tty_struct *tty = file_tty(file);
  	struct tty_ldisc *ld;
 	ssize_t ret;
@@ -1054,18 +1119,15 @@ static ssize_t tty_write(struct file *file, const char __user *buf,
 	if (tty->ops->write_room == NULL)
 		tty_err(tty, "missing write_room method\n");
 	ld = tty_ldisc_ref_wait(tty);
-	if (!ld)
-		return hung_up_tty_write(file, buf, count, ppos);
-	if (!ld->ops->write)
+	if (!ld || !ld->ops->write)
 		ret = -EIO;
 	else
-		ret = do_tty_write(ld->ops->write, tty, file, buf, count);
+		ret = do_tty_write(ld->ops->write, tty, file, from);
 	tty_ldisc_deref(ld);
 	return ret;
 }
 
-ssize_t redirected_tty_write(struct file *file, const char __user *buf,
-						size_t count, loff_t *ppos)
+ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter)
 {
 	struct file *p = NULL;
 
@@ -1076,11 +1138,11 @@ ssize_t redirected_tty_write(struct file *file, const char __user *buf,
 
 	if (p) {
 		ssize_t res;
-		res = vfs_write(p, buf, count, &p->f_pos);
+		res = vfs_iocb_iter_write(p, iocb, iter);
 		fput(p);
 		return res;
 	}
-	return tty_write(file, buf, count, ppos);
+	return tty_write(iocb, iter);
 }
 
 /*
@@ -2332,7 +2394,7 @@ static int tioccons(struct file *file)
 {
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
-	if (file->f_op->write == redirected_tty_write) {
+	if (file->f_op->write_iter == redirected_tty_write) {
 		struct file *f;
 		spin_lock(&redirect_lock);
 		f = redirect;
@@ -2925,7 +2987,7 @@ static long tty_compat_ioctl(struct file *file, unsigned int cmd,
 
 static int this_tty(const void *t, struct file *file, unsigned fd)
 {
-	if (likely(file->f_op->read != tty_read))
+	if (likely(file->f_op->read_iter != tty_read))
 		return 0;
 	return file_tty(file) != t ? 0 : fd + 1;
 }