[PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[Konstantin Khlebnikov]

cleanup hack added in v2.6.27-3203-g15582d3

comment from that patch:

: pty: If the administrator creates a device for a ptmx slave we should not error
:
: The open path for ptmx slaves is via the ptmx device. Opening them any
: other way is not allowed. Vegard Nossum found that previously this was not
: the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
:
: Signed-off-by: Alan Cox <alan@redhat.com>
: Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devpts_get_tty() returns non-null only for inodes on devpts, but there is no
inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them.
Thus we can completely forbid lookup for master-devices and eliminate that hack in
tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
---
 drivers/tty/pty.c    |    8 +++-----
 drivers/tty/tty_io.c |   12 ++----------
 include/linux/tty.h  |    3 +--
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index e18604b..d2bf3c1 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -526,10 +526,8 @@ static int pty_unix98_ioctl(struct tty_struct *tty,
 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 		struct inode *ptm_inode, int idx)
 {
-	struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
-	if (tty)
-		tty = tty->link;
-	return tty;
+	/* Master must be open via /dev/ptmx */
+	return ERR_PTR(-EIO);
 }
 
 /**
@@ -685,7 +683,7 @@ static int ptmx_open(struct inode *inode, struct file *filp)
 
 	mutex_lock(&tty_mutex);
 	tty_lock();
-	tty = tty_init_dev(ptm_driver, index, 1);
+	tty = tty_init_dev(ptm_driver, index);
 	mutex_unlock(&tty_mutex);
 
 	if (IS_ERR(tty)) {
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 05085be..7cddf91 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1366,7 +1366,6 @@ static int tty_reopen(struct tty_struct *tty)
  *	@driver: tty driver we are opening a device on
  *	@idx: device index
  *	@ret_tty: returned tty structure
- *	@first_ok: ok to open a new device (used by ptmx)
  *
  *	Prepare a tty device. This may not be a "new" clean device but
  *	could also be an active device. The pty drivers require special
@@ -1386,18 +1385,11 @@ static int tty_reopen(struct tty_struct *tty)
  * relaxed for the (most common) case of reopening a tty.
  */
 
-struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
-								int first_ok)
+struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
 {
 	struct tty_struct *tty;
 	int retval;
 
-	/* Check if pty master is being opened multiple times */
-	if (driver->subtype == PTY_TYPE_MASTER &&
-		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
-		return ERR_PTR(-EIO);
-	}
-
 	/*
 	 * First time open is complex, especially for PTY devices.
 	 * This code guarantees that either everything succeeds and the
@@ -1909,7 +1901,7 @@ got_driver:
 		if (retval)
 			tty = ERR_PTR(retval);
 	} else
-		tty = tty_init_dev(driver, index, 0);
+		tty = tty_init_dev(driver, index);
 
 	mutex_unlock(&tty_mutex);
 	tty_driver_kref_put(driver);
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 5dbb3cb..d3ebd76 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -480,8 +480,7 @@ extern void free_tty_struct(struct tty_struct *tty);
 extern void initialize_tty_struct(struct tty_struct *tty,
 		struct tty_driver *driver, int idx);
 extern void deinitialize_tty_struct(struct tty_struct *tty);
-extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
-								int first_ok);
+extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
 extern int tty_release(struct inode *inode, struct file *filp);
 extern int tty_init_termios(struct tty_struct *tty);
 

Re: [PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[Greg KH]

On Mon, Jan 02, 2012 at 09:22:31PM +0400, Konstantin Khlebnikov wrote:
> cleanup hack added in v2.6.27-3203-g15582d3
> 
> comment from that patch:
> 
> : pty: If the administrator creates a device for a ptmx slave we should not error
> :
> : The open path for ptmx slaves is via the ptmx device. Opening them any
> : other way is not allowed. Vegard Nossum found that previously this was not
> : the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
> :
> : Signed-off-by: Alan Cox <alan@redhat.com>
> : Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Any reason why you didn't include these two people on this patch?
Perhaps they might wish to review it...

greg k-h

Re: [PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[Konstantin Khlebnikov]

Greg KH wrote:
> On Mon, Jan 02, 2012 at 09:22:31PM +0400, Konstantin Khlebnikov wrote:
>> cleanup hack added in v2.6.27-3203-g15582d3
>>
>> comment from that patch:
>>
>> : pty: If the administrator creates a device for a ptmx slave we should not error
>> :
>> : The open path for ptmx slaves is via the ptmx device. Opening them any
>> : other way is not allowed. Vegard Nossum found that previously this was not
>> : the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
>> :
>> : Signed-off-by: Alan Cox<alan@redhat.com>
>> : Signed-off-by: Linus Torvalds<torvalds@linux-foundation.org>
>
> Any reason why you didn't include these two people on this patch?
> Perhaps they might wish to review it...

This is just simple cleanup patch.

>
> greg k-h

Re: [PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[Greg KH]

On Tue, Jan 03, 2012 at 02:29:08AM +0400, Konstantin Khlebnikov wrote:
> Greg KH wrote:
> >On Mon, Jan 02, 2012 at 09:22:31PM +0400, Konstantin Khlebnikov wrote:
> >>cleanup hack added in v2.6.27-3203-g15582d3
> >>
> >>comment from that patch:
> >>
> >>: pty: If the administrator creates a device for a ptmx slave we should not error
> >>:
> >>: The open path for ptmx slaves is via the ptmx device. Opening them any
> >>: other way is not allowed. Vegard Nossum found that previously this was not
> >>: the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
> >>:
> >>: Signed-off-by: Alan Cox<alan@redhat.com>
> >>: Signed-off-by: Linus Torvalds<torvalds@linux-foundation.org>
> >
> >Any reason why you didn't include these two people on this patch?
> >Perhaps they might wish to review it...
> 
> This is just simple cleanup patch.

Even so, please resend and copy them.

greg k-h

[PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[Konstantin Khlebnikov]

cleanup hack added in v2.6.27-3203-g15582d3

comment from that patch:

: pty: If the administrator creates a device for a ptmx slave we should not error
:
: The open path for ptmx slaves is via the ptmx device. Opening them any
: other way is not allowed. Vegard Nossum found that previously this was not
: the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
:
: Signed-off-by: Alan Cox <alan@redhat.com>
: Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devpts_get_tty() returns non-null only for inodes on devpts, but there is no
inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them.
Thus we can completely forbid lookup for master-devices and eliminate that hack in
tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
---
 drivers/tty/pty.c    |    8 +++-----
 drivers/tty/tty_io.c |   12 ++----------
 include/linux/tty.h  |    3 +--
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index e18604b..d2bf3c1 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -526,10 +526,8 @@ static int pty_unix98_ioctl(struct tty_struct *tty,
 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 		struct inode *ptm_inode, int idx)
 {
-	struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
-	if (tty)
-		tty = tty->link;
-	return tty;
+	/* Master must be open via /dev/ptmx */
+	return ERR_PTR(-EIO);
 }
 
 /**
@@ -685,7 +683,7 @@ static int ptmx_open(struct inode *inode, struct file *filp)
 
 	mutex_lock(&tty_mutex);
 	tty_lock();
-	tty = tty_init_dev(ptm_driver, index, 1);
+	tty = tty_init_dev(ptm_driver, index);
 	mutex_unlock(&tty_mutex);
 
 	if (IS_ERR(tty)) {
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 05085be..7cddf91 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1366,7 +1366,6 @@ static int tty_reopen(struct tty_struct *tty)
  *	@driver: tty driver we are opening a device on
  *	@idx: device index
  *	@ret_tty: returned tty structure
- *	@first_ok: ok to open a new device (used by ptmx)
  *
  *	Prepare a tty device. This may not be a "new" clean device but
  *	could also be an active device. The pty drivers require special
@@ -1386,18 +1385,11 @@ static int tty_reopen(struct tty_struct *tty)
  * relaxed for the (most common) case of reopening a tty.
  */
 
-struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
-								int first_ok)
+struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
 {
 	struct tty_struct *tty;
 	int retval;
 
-	/* Check if pty master is being opened multiple times */
-	if (driver->subtype == PTY_TYPE_MASTER &&
-		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
-		return ERR_PTR(-EIO);
-	}
-
 	/*
 	 * First time open is complex, especially for PTY devices.
 	 * This code guarantees that either everything succeeds and the
@@ -1909,7 +1901,7 @@ got_driver:
 		if (retval)
 			tty = ERR_PTR(retval);
 	} else
-		tty = tty_init_dev(driver, index, 0);
+		tty = tty_init_dev(driver, index);
 
 	mutex_unlock(&tty_mutex);
 	tty_driver_kref_put(driver);
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 5dbb3cb..d3ebd76 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -480,8 +480,7 @@ extern void free_tty_struct(struct tty_struct *tty);
 extern void initialize_tty_struct(struct tty_struct *tty,
 		struct tty_driver *driver, int idx);
 extern void deinitialize_tty_struct(struct tty_struct *tty);
-extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
-								int first_ok);
+extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
 extern int tty_release(struct inode *inode, struct file *filp);
 extern int tty_init_termios(struct tty_struct *tty);
 

Re: [PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[Linus Torvalds]

Looks ok as far as I can tell, and does indeed clean things up. I
assume somebody tested the case that we used to have issues with?

                    Linus

On Tue, Jan 3, 2012 at 12:51 AM, Konstantin Khlebnikov
<khlebnikov@openvz.org> wrote:
> cleanup hack added in v2.6.27-3203-g15582d3
>
> comment from that patch:
>
> : pty: If the administrator creates a device for a ptmx slave we should not error
> :
> : The open path for ptmx slaves is via the ptmx device. Opening them any
> : other way is not allowed. Vegard Nossum found that previously this was not
> : the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
> :
> : Signed-off-by: Alan Cox <alan@redhat.com>
> : Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
>
> devpts_get_tty() returns non-null only for inodes on devpts, but there is no
> inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them.
> Thus we can completely forbid lookup for master-devices and eliminate that hack in
> tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
> ---
>  drivers/tty/pty.c    |    8 +++-----
>  drivers/tty/tty_io.c |   12 ++----------
>  include/linux/tty.h  |    3 +--
>  3 files changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
> index e18604b..d2bf3c1 100644
> --- a/drivers/tty/pty.c
> +++ b/drivers/tty/pty.c
> @@ -526,10 +526,8 @@ static int pty_unix98_ioctl(struct tty_struct *tty,
>  static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
>                struct inode *ptm_inode, int idx)
>  {
> -       struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
> -       if (tty)
> -               tty = tty->link;
> -       return tty;
> +       /* Master must be open via /dev/ptmx */
> +       return ERR_PTR(-EIO);
>  }
>
>  /**
> @@ -685,7 +683,7 @@ static int ptmx_open(struct inode *inode, struct file *filp)
>
>        mutex_lock(&tty_mutex);
>        tty_lock();
> -       tty = tty_init_dev(ptm_driver, index, 1);
> +       tty = tty_init_dev(ptm_driver, index);
>        mutex_unlock(&tty_mutex);
>
>        if (IS_ERR(tty)) {
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 05085be..7cddf91 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -1366,7 +1366,6 @@ static int tty_reopen(struct tty_struct *tty)
>  *     @driver: tty driver we are opening a device on
>  *     @idx: device index
>  *     @ret_tty: returned tty structure
> - *     @first_ok: ok to open a new device (used by ptmx)
>  *
>  *     Prepare a tty device. This may not be a "new" clean device but
>  *     could also be an active device. The pty drivers require special
> @@ -1386,18 +1385,11 @@ static int tty_reopen(struct tty_struct *tty)
>  * relaxed for the (most common) case of reopening a tty.
>  */
>
> -struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
> -                                                               int first_ok)
> +struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
>  {
>        struct tty_struct *tty;
>        int retval;
>
> -       /* Check if pty master is being opened multiple times */
> -       if (driver->subtype == PTY_TYPE_MASTER &&
> -               (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
> -               return ERR_PTR(-EIO);
> -       }
> -
>        /*
>         * First time open is complex, especially for PTY devices.
>         * This code guarantees that either everything succeeds and the
> @@ -1909,7 +1901,7 @@ got_driver:
>                if (retval)
>                        tty = ERR_PTR(retval);
>        } else
> -               tty = tty_init_dev(driver, index, 0);
> +               tty = tty_init_dev(driver, index);
>
>        mutex_unlock(&tty_mutex);
>        tty_driver_kref_put(driver);
> diff --git a/include/linux/tty.h b/include/linux/tty.h
> index 5dbb3cb..d3ebd76 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -480,8 +480,7 @@ extern void free_tty_struct(struct tty_struct *tty);
>  extern void initialize_tty_struct(struct tty_struct *tty,
>                struct tty_driver *driver, int idx);
>  extern void deinitialize_tty_struct(struct tty_struct *tty);
> -extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
> -                                                               int first_ok);
> +extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
>  extern int tty_release(struct inode *inode, struct file *filp);
>  extern int tty_init_termios(struct tty_struct *tty);
>
>

Re: [PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[Konstantin Khlebnikov]

Linus Torvalds wrote:
> Looks ok as far as I can tell, and does indeed clean things up. I
> assume somebody tested the case that we used to have issues with?

Yes of course I tested it.

>
>                      Linus
>
> On Tue, Jan 3, 2012 at 12:51 AM, Konstantin Khlebnikov
> <khlebnikov@openvz.org>  wrote:
>> cleanup hack added in v2.6.27-3203-g15582d3
>>
>> comment from that patch:
>>
>> : pty: If the administrator creates a device for a ptmx slave we should not error
>> :
>> : The open path for ptmx slaves is via the ptmx device. Opening them any
>> : other way is not allowed. Vegard Nossum found that previously this was not
>> : the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
>> :
>> : Signed-off-by: Alan Cox<alan@redhat.com>
>> : Signed-off-by: Linus Torvalds<torvalds@linux-foundation.org>
>>
>> devpts_get_tty() returns non-null only for inodes on devpts, but there is no
>> inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them.
>> Thus we can completely forbid lookup for master-devices and eliminate that hack in
>> tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().
>>
>> Signed-off-by: Konstantin Khlebnikov<khlebnikov@openvz.org>

Re: [PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[Greg KH]

On Tue, Jan 03, 2012 at 12:51:11PM +0400, Konstantin Khlebnikov wrote:
> cleanup hack added in v2.6.27-3203-g15582d3
> 
> comment from that patch:
> 
> : pty: If the administrator creates a device for a ptmx slave we should not error
> :
> : The open path for ptmx slaves is via the ptmx device. Opening them any
> : other way is not allowed. Vegard Nossum found that previously this was not
> : the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
> :
> : Signed-off-by: Alan Cox <alan@redhat.com>
> : Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> 
> devpts_get_tty() returns non-null only for inodes on devpts, but there is no
> inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them.
> Thus we can completely forbid lookup for master-devices and eliminate that hack in
> tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>

What tree did you make this patch against?  I get fuzz warnings when
applying it to the tty-next branch (it's in the linux-next releases).

Please rediff it and resend it.

thanks,

greg k-h

[PATCH for tty-next] tty: cleanup prohibition of direct opening for unix98 pty master

[Konstantin Khlebnikov]

cleanup hack added in v2.6.27-3203-g15582d3

comment from that patch:

: pty: If the administrator creates a device for a ptmx slave we should not error
:
: The open path for ptmx slaves is via the ptmx device. Opening them any
: other way is not allowed. Vegard Nossum found that previously this was not
: the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
:
: Signed-off-by: Alan Cox <alan@redhat.com>
: Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devpts_get_tty() returns non-null only for inodes on devpts, but there is no
inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them.
Thus we can completely forbid lookup for master-devices and eliminate that hack in
tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
---
 drivers/tty/pty.c    |    8 +++-----
 drivers/tty/tty_io.c |   12 ++----------
 include/linux/tty.h  |    3 +--
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index d8653ab..03147fa 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -515,10 +515,8 @@ static int pty_unix98_ioctl(struct tty_struct *tty,
 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 		struct inode *ptm_inode, int idx)
 {
-	struct tty_struct *tty = devpts_get_tty(ptm_inode, idx);
-	if (tty)
-		tty = tty->link;
-	return tty;
+	/* Master must be open via /dev/ptmx */
+	return ERR_PTR(-EIO);
 }
 
 /**
@@ -677,7 +675,7 @@ static int ptmx_open(struct inode *inode, struct file *filp)
 
 	mutex_lock(&tty_mutex);
 	tty_lock();
-	tty = tty_init_dev(ptm_driver, index, 1);
+	tty = tty_init_dev(ptm_driver, index);
 	mutex_unlock(&tty_mutex);
 
 	if (IS_ERR(tty)) {
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 57c3743..a4fd717 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1365,7 +1365,6 @@ static int tty_reopen(struct tty_struct *tty)
  *	@driver: tty driver we are opening a device on
  *	@idx: device index
  *	@ret_tty: returned tty structure
- *	@first_ok: ok to open a new device (used by ptmx)
  *
  *	Prepare a tty device. This may not be a "new" clean device but
  *	could also be an active device. The pty drivers require special
@@ -1385,18 +1384,11 @@ static int tty_reopen(struct tty_struct *tty)
  * relaxed for the (most common) case of reopening a tty.
  */
 
-struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
-								int first_ok)
+struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
 {
 	struct tty_struct *tty;
 	int retval;
 
-	/* Check if pty master is being opened multiple times */
-	if (driver->subtype == PTY_TYPE_MASTER &&
-		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
-		return ERR_PTR(-EIO);
-	}
-
 	/*
 	 * First time open is complex, especially for PTY devices.
 	 * This code guarantees that either everything succeeds and the
@@ -1950,7 +1942,7 @@ retry_open:
 		if (retval)
 			tty = ERR_PTR(retval);
 	} else
-		tty = tty_init_dev(driver, index, 0);
+		tty = tty_init_dev(driver, index);
 
 	mutex_unlock(&tty_mutex);
 	if (driver)
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 5dbb3cb..d3ebd76 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -480,8 +480,7 @@ extern void free_tty_struct(struct tty_struct *tty);
 extern void initialize_tty_struct(struct tty_struct *tty,
 		struct tty_driver *driver, int idx);
 extern void deinitialize_tty_struct(struct tty_struct *tty);
-extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
-								int first_ok);
+extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
 extern int tty_release(struct inode *inode, struct file *filp);
 extern int tty_init_termios(struct tty_struct *tty);
 

Re: [PATCH] tty: cleanup prohibition of direct opening for unix98 pty master

[Konstantin Khlebnikov]

Greg KH wrote:
> On Tue, Jan 03, 2012 at 12:51:11PM +0400, Konstantin Khlebnikov wrote:
>> cleanup hack added in v2.6.27-3203-g15582d3
>>
>> comment from that patch:
>>
>> : pty: If the administrator creates a device for a ptmx slave we should not error
>> :
>> : The open path for ptmx slaves is via the ptmx device. Opening them any
>> : other way is not allowed. Vegard Nossum found that previously this was not
>> : the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
>> :
>> : Signed-off-by: Alan Cox<alan@redhat.com>
>> : Signed-off-by: Linus Torvalds<torvalds@linux-foundation.org>
>>
>> devpts_get_tty() returns non-null only for inodes on devpts, but there is no
>> inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them.
>> Thus we can completely forbid lookup for master-devices and eliminate that hack in
>> tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().
>>
>> Signed-off-by: Konstantin Khlebnikov<khlebnikov@openvz.org>
>
> What tree did you make this patch against?  I get fuzz warnings when
> applying it to the tty-next branch (it's in the linux-next releases).
>
> Please rediff it and resend it.

Sorry for that, I did not expect such activity in tty-layer =)

>
> thanks,
>
> greg k-h