2017-06-20 20:34:50

by Arnd Bergmann

Subject: [PATCH] tty: hide unused pty_get_peer function

TIOCGPTPEER is only used for unix98 PTYs, and we get a warning
when those are disabled:

drivers/tty/pty.c:466:12: error: 'pty_get_peer' defined but not used [-Werror=unused-function]

This moves the respective functions inside of the existing #ifdef.

Fixes: 54ebbfb16034 ("tty: add TIOCGPTPEER ioctl")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/tty/pty.c | 85 +++++++++++++++++++++++++++----------------------------
1 file changed, 42 insertions(+), 43 deletions(-)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index d1399aac05a1..284749fb0f6b 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -448,48 +448,6 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
return retval;
}

-/**
- * pty_open_peer - open the peer of a pty
- * @tty: the peer of the pty being opened
- *
- * Open the cached dentry in tty->link, providing a safe way for userspace
- * to get the slave end of a pty (where they have the master fd and cannot
- * access or trust the mount namespace /dev/pts was mounted inside).
- */
-static struct file *pty_open_peer(struct tty_struct *tty, int flags)
-{
- if (tty->driver->subtype != PTY_TYPE_MASTER)
- return ERR_PTR(-EIO);
- return dentry_open(tty->link->driver_data, flags, current_cred());
-}
-
-static int pty_get_peer(struct tty_struct *tty, int flags)
-{
- int fd = -1;
- struct file *filp = NULL;
- int retval = -EINVAL;
-
- fd = get_unused_fd_flags(0);
- if (fd < 0) {
- retval = fd;
- goto err;
- }
-
- filp = pty_open_peer(tty, flags);
- if (IS_ERR(filp)) {
- retval = PTR_ERR(filp);
- goto err_put;
- }
-
- fd_install(fd, filp);
- return fd;
-
-err_put:
- put_unused_fd(fd);
-err:
- return retval;
-}
-
static void pty_cleanup(struct tty_struct *tty)
{
tty_port_put(tty->port);
@@ -646,9 +604,50 @@ static inline void legacy_pty_init(void) { }

/* Unix98 devices */
#ifdef CONFIG_UNIX98_PTYS
-
static struct cdev ptmx_cdev;

+/**
+ * pty_open_peer - open the peer of a pty
+ * @tty: the peer of the pty being opened
+ *
+ * Open the cached dentry in tty->link, providing a safe way for userspace
+ * to get the slave end of a pty (where they have the master fd and cannot
+ * access or trust the mount namespace /dev/pts was mounted inside).
+ */
+static struct file *pty_open_peer(struct tty_struct *tty, int flags)
+{
+ if (tty->driver->subtype != PTY_TYPE_MASTER)
+ return ERR_PTR(-EIO);
+ return dentry_open(tty->link->driver_data, flags, current_cred());
+}
+
+static int pty_get_peer(struct tty_struct *tty, int flags)
+{
+ int fd = -1;
+ struct file *filp = NULL;
+ int retval = -EINVAL;
+
+ fd = get_unused_fd_flags(0);
+ if (fd < 0) {
+ retval = fd;
+ goto err;
+ }
+
+ filp = pty_open_peer(tty, flags);
+ if (IS_ERR(filp)) {
+ retval = PTR_ERR(filp);
+ goto err_put;
+ }
+
+ fd_install(fd, filp);
+ return fd;
+
+err_put:
+ put_unused_fd(fd);
+err:
+ return retval;
+}
+
static int pty_unix98_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg)
{
--
2.9.0

2017-06-20 22:39:52

by Kees Cook

Subject: Re: [PATCH] tty: hide unused pty_get_peer function

On Tue, Jun 20, 2017 at 1:34 PM, Arnd Bergmann <[email protected]> wrote:
> TIOCGPTPEER is only used for unix98 PTYs, and we get a warning
> when those are disabled:
>
> drivers/tty/pty.c:466:12: error: 'pty_get_peer' defined but not used [-Werror=unused-function]
>
> This moves the respective functions inside of the existing #ifdef.
>
> Fixes: 54ebbfb16034 ("tty: add TIOCGPTPEER ioctl")
> Signed-off-by: Arnd Bergmann <[email protected]>

Reviewed-by: Kees Cook <[email protected]>

-Kees

--
Kees Cook
Pixel Security

2017-06-20 23:10:46

by Aleksa Sarai

Subject: Re: [PATCH] tty: hide unused pty_get_peer function

> TIOCGPTPEER is only used for unix98 PTYs, and we get a warning
> when those are disabled:
>
> drivers/tty/pty.c:466:12: error: 'pty_get_peer' defined but not used [-Werror=unused-function]
>
> This moves the respective functions inside of the existing #ifdef.
>
> Fixes: 54ebbfb16034 ("tty: add TIOCGPTPEER ioctl")
> Signed-off-by: Arnd Bergmann <[email protected]>

Oops, I missed that.

Acked-by: Aleksa Sarai <[email protected]>

--
Aleksa Sarai
Software Engineer (Containers)
SUSE Linux GmbH
https://www.cyphar.com/