[PATCH v2 03/15] tty: audit: Remove icanon mode from call chain

[Peter Hurley]

The tty termios bits cannot change while n_tty_read() is in the
i/o loop; the termios_rwsem ensures mutual exclusion with termios
changes in n_tty_set_termios(). Check L_ICANON() directly and
eliminate icanon parameter.

NB: tty_audit_add_data() => tty_audit_buf_get() => tty_audit_buf_alloc()
is a single path; ie., tty_audit_buf_get() and tty_audit_buf_alloc()
have no other callers.

Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
 drivers/tty/n_tty.c     |  6 +++---
 drivers/tty/tty_audit.c | 22 +++++++++-------------
 include/linux/tty.h     |  4 ++--
 3 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index eeae6bc..5d060fc 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -162,7 +162,7 @@ static int tty_copy_to_user(struct tty_struct *tty, void __user *to,
 	int uncopied;
 
 	if (n > size) {
-		tty_audit_add_data(tty, from, size, ldata->icanon);
+		tty_audit_add_data(tty, from, size);
 		uncopied = copy_to_user(to, from, size);
 		if (uncopied)
 			return uncopied;
@@ -171,7 +171,7 @@ static int tty_copy_to_user(struct tty_struct *tty, void __user *to,
 		from = ldata->read_buf;
 	}
 
-	tty_audit_add_data(tty, from, n, ldata->icanon);
+	tty_audit_add_data(tty, from, n);
 	return copy_to_user(to, from, n);
 }
 
@@ -1984,7 +1984,7 @@ static int copy_from_read_buf(struct tty_struct *tty,
 		retval = copy_to_user(*b, from, n);
 		n -= retval;
 		is_eof = n == 1 && *from == EOF_CHAR(tty);
-		tty_audit_add_data(tty, from, n, ldata->icanon);
+		tty_audit_add_data(tty, from, n);
 		smp_store_release(&ldata->read_tail, ldata->read_tail + n);
 		/* Turn single EOF into zero-length read */
 		if (L_EXTPROC(tty) && ldata->icanon && is_eof &&
diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c
index ead924e..d2a004a 100644
--- a/drivers/tty/tty_audit.c
+++ b/drivers/tty/tty_audit.c
@@ -22,8 +22,7 @@ struct tty_audit_buf {
 	unsigned char *data;	/* Allocated size N_TTY_BUF_SIZE */
 };
 
-static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
-						 unsigned icanon)
+static struct tty_audit_buf *tty_audit_buf_alloc(struct tty_struct *tty)
 {
 	struct tty_audit_buf *buf;
 
@@ -35,9 +34,9 @@ static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
 		goto err_buf;
 	atomic_set(&buf->count, 1);
 	mutex_init(&buf->mutex);
-	buf->major = major;
-	buf->minor = minor;
-	buf->icanon = icanon;
+	buf->major = tty->driver->major;
+	buf->minor = tty->driver->minor_start + tty->index;
+	buf->icanon = !!L_ICANON(tty);
 	buf->valid = 0;
 	return buf;
 
@@ -216,8 +215,7 @@ int tty_audit_push_current(void)
  *	if TTY auditing is disabled or out of memory.  Otherwise, return a new
  *	reference to the buffer.
  */
-static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty,
-		unsigned icanon)
+static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty)
 {
 	struct tty_audit_buf *buf, *buf2;
 	unsigned long flags;
@@ -234,9 +232,7 @@ static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty,
 	}
 	spin_unlock_irqrestore(&current->sighand->siglock, flags);
 
-	buf2 = tty_audit_buf_alloc(tty->driver->major,
-				   tty->driver->minor_start + tty->index,
-				   icanon);
+	buf2 = tty_audit_buf_alloc(tty);
 	if (buf2 == NULL) {
 		audit_log_lost("out of memory in TTY auditing");
 		return NULL;
@@ -265,13 +261,13 @@ static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty,
  *
  *	Audit @data of @size from @tty, if necessary.
  */
-void tty_audit_add_data(struct tty_struct *tty, const void *data,
-			size_t size, unsigned icanon)
+void tty_audit_add_data(struct tty_struct *tty, const void *data, size_t size)
 {
 	struct tty_audit_buf *buf;
 	int major, minor;
 	int audit_log_tty_passwd;
 	unsigned long flags;
+	unsigned int icanon = !!L_ICANON(tty);
 
 	if (unlikely(size == 0))
 		return;
@@ -286,7 +282,7 @@ void tty_audit_add_data(struct tty_struct *tty, const void *data,
 	if (!audit_log_tty_passwd && icanon && !L_ECHO(tty))
 		return;
 
-	buf = tty_audit_buf_get(tty, icanon);
+	buf = tty_audit_buf_get(tty);
 	if (!buf)
 		return;
 
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 56d1133..c1d1f08 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -604,7 +604,7 @@ extern void n_tty_inherit_ops(struct tty_ldisc_ops *ops);
 /* tty_audit.c */
 #ifdef CONFIG_AUDIT
 extern void tty_audit_add_data(struct tty_struct *tty, const void *data,
-			       size_t size, unsigned icanon);
+			       size_t size);
 extern void tty_audit_exit(void);
 extern void tty_audit_fork(struct signal_struct *sig);
 extern void tty_audit_tiocsti(struct tty_struct *tty, char ch);
@@ -612,7 +612,7 @@ extern void tty_audit_push(struct tty_struct *tty);
 extern int tty_audit_push_current(void);
 #else
 static inline void tty_audit_add_data(struct tty_struct *tty, const void *data,
-				      size_t size, unsigned icanon)
+				      size_t size)
 {
 }
 static inline void tty_audit_tiocsti(struct tty_struct *tty, char ch)
-- 
2.7.0