[PATCH 2/4] devpts: Set the default permissions of /dev/pts/ptmx and /dev/ptmx to 0666

From: Eric W. Biederman
Date: Sat Sep 22 2012 - 23:49:36 EST



These are difference instances of the same device not so it only
makes sense that they would have the same default permissions.

Move the definitions of DEVPTS_DEEFAULT_PTMX_MODE and PTM_MINOR
into devpts_fs.h so we can use the same definitions throughout.

Acked-by: "Serge E. Hallyn" <serge@xxxxxxxxxx>
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
drivers/tty/pty.c | 6 +++---
drivers/tty/tty_io.c | 5 +++--
fs/devpts/inode.c | 8 --------
include/linux/devpts_fs.h | 3 +++
4 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 5505ffc..6beb7e1 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -722,10 +722,10 @@ static void __init unix98_pty_init(void)
ptmx_fops.open = ptmx_open;

cdev_init(&ptmx_cdev, &ptmx_fops);
- if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
- register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
+ if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, PTMX_MINOR), 1) ||
+ register_chrdev_region(MKDEV(TTYAUX_MAJOR, PTMX_MINOR), 1, "/dev/ptmx") < 0)
panic("Couldn't register /dev/ptmx driver\n");
- device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
+ device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, PTMX_MINOR), NULL, "ptmx");
}

#else
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index b425c79..6c3a7c2 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3314,9 +3314,10 @@ static char *tty_devnode(struct device *dev, umode_t *mode)
{
if (!mode)
return NULL;
- if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
- dev->devt == MKDEV(TTYAUX_MAJOR, 2))
+ if (dev->devt == MKDEV(TTYAUX_MAJOR, 0))
*mode = 0666;
+ if (dev->devt == MKDEV(TTYAUX_MAJOR, PTMX_MINOR))
+ *mode = DEVPTS_DEFAULT_PTMX_MODE;
return NULL;
}

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 5f0d64e..61b54aa 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -27,14 +27,6 @@
#include <linux/seq_file.h>

#define DEVPTS_DEFAULT_MODE 0600
-/*
- * ptmx is a new node in /dev/pts and will be unused in legacy (single-
- * instance) mode. To prevent surprises in user space, set permissions of
- * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful
- * permissions.
- */
-#define DEVPTS_DEFAULT_PTMX_MODE 0000
-#define PTMX_MINOR 2

/*
* sysctl support for setting limits on the number of Unix98 ptys allocated.
diff --git a/include/linux/devpts_fs.h b/include/linux/devpts_fs.h
index 5ce0e5f..2d539ae 100644
--- a/include/linux/devpts_fs.h
+++ b/include/linux/devpts_fs.h
@@ -15,6 +15,9 @@

#include <linux/errno.h>

+#define DEVPTS_DEFAULT_PTMX_MODE 0666
+#define PTMX_MINOR 2
+
#ifdef CONFIG_UNIX98_PTYS

int devpts_new_index(struct inode *ptmx_inode);
--
1.7.5.4

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