* [PATCH] linux ttyname and ttyname_r: do not return wrong results
2016-11-08 16:56 [PATCH] linux ttyname and ttyname_r: do not return wrong results Christian Brauner
@ 2016-11-08 16:56 ` Christian Brauner
2016-11-10 18:04 ` Serge E. Hallyn
2016-11-22 2:10 ` Dmitry V. Levin
2016-11-22 0:14 ` Christian Brauner
1 sibling, 2 replies; 5+ messages in thread
From: Christian Brauner @ 2016-11-08 16:56 UTC (permalink / raw)
To: libc-alpha, serge; +Cc: Christian Brauner
If a link (say /proc/self/fd/0) pointing to a device, say /dev/pts/2, in a
parent mount namespace is passed to ttyname, and a /dev/pts/2 exists (in a
different devpts) in the current namespace, then it returns /dev/pts/2. But
/dev/pts/2 is NOT the current tty, it is a different file and device.
Detect this case and return ENODEV. Userspace can choose to take this as a hint
that the fd points to a tty device but to act on the fd rather than the link.
Signed-off-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Christian Brauner <christian.brauner@canonical.com>
---
Changelog: 2016-11-08
- remove obsolete comment in ttyname_r.c
- move is_pty() to common header file and mark as static inline
---
sysdeps/unix/sysv/linux/ttyname.c | 17 +++++++++++++----
sysdeps/unix/sysv/linux/ttyname.h | 35 +++++++++++++++++++++++++++++++++++
sysdeps/unix/sysv/linux/ttyname_r.c | 18 ++++++++++++++----
3 files changed, 62 insertions(+), 8 deletions(-)
create mode 100644 sysdeps/unix/sysv/linux/ttyname.h
diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c
index 7a001b4..dabed22 100644
--- a/sysdeps/unix/sysv/linux/ttyname.c
+++ b/sysdeps/unix/sysv/linux/ttyname.c
@@ -25,9 +25,12 @@
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
+#include <sys/sysmacros.h>
#include <_itoa.h>
+#include "ttyname.h"
+
#if 0
/* Is this used anywhere? It is not exported. */
char *__ttyname;
@@ -170,12 +173,18 @@ ttyname (int fd)
#ifdef _STATBUF_ST_RDEV
&& S_ISCHR (st1.st_mode)
&& st1.st_rdev == st.st_rdev
-#else
- && st1.st_ino == st.st_ino
- && st1.st_dev == st.st_dev
#endif
- )
+ && st1.st_ino == st.st_ino
+ && st1.st_dev == st.st_dev)
return ttyname_buf;
+
+ /* If the link doesn't exist, then it points to a device in another
+ namespace. */
+ if (is_pty (&st))
+ {
+ __set_errno (ENODEV);
+ return NULL;
+ }
}
if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))
diff --git a/sysdeps/unix/sysv/linux/ttyname.h b/sysdeps/unix/sysv/linux/ttyname.h
new file mode 100644
index 0000000..19af6e6
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/ttyname.h
@@ -0,0 +1,35 @@
+/* Copyright (C) 2004-2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If
+ not, see <http://www.gnu.org/licenses/>. */
+
+#include <unistd.h>
+#include <sys/sysmacros.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+/* Return true if this is a UNIX98 pty device, as defined in
+ linux/Documentation/devices.txt. */
+static inline int
+is_pty (struct stat64 *sb)
+{
+#ifdef _STATBUF_ST_RDEV
+ int m = major (sb->st_rdev);
+ return (136 <= m && m <= 143);
+#else
+ return false;
+#endif
+}
+
diff --git a/sysdeps/unix/sysv/linux/ttyname_r.c b/sysdeps/unix/sysv/linux/ttyname_r.c
index d15bc74..542114b 100644
--- a/sysdeps/unix/sysv/linux/ttyname_r.c
+++ b/sysdeps/unix/sysv/linux/ttyname_r.c
@@ -25,9 +25,12 @@
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
+#include <sys/sysmacros.h>
#include <_itoa.h>
+#include "ttyname.h"
+
static int getttyname_r (char *buf, size_t buflen,
dev_t mydev, ino64_t myino, int save,
int *dostat) internal_function;
@@ -152,12 +155,19 @@ __ttyname_r (int fd, char *buf, size_t buflen)
#ifdef _STATBUF_ST_RDEV
&& S_ISCHR (st1.st_mode)
&& st1.st_rdev == st.st_rdev
-#else
- && st1.st_ino == st.st_ino
- && st1.st_dev == st.st_dev
#endif
- )
+ && st1.st_ino == st.st_ino
+ && st1.st_dev == st.st_dev)
return 0;
+
+ /* If the link doesn't exist, then it points to a device in another
+ * namespace.
+ */
+ if (is_pty (&st))
+ {
+ __set_errno (ENODEV);
+ return ENODEV;
+ }
}
/* Prepare the result buffer. */
--
2.9.3
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] linux ttyname and ttyname_r: do not return wrong results
2016-11-08 16:56 [PATCH] linux ttyname and ttyname_r: do not return wrong results Christian Brauner
2016-11-08 16:56 ` Christian Brauner
@ 2016-11-22 0:14 ` Christian Brauner
1 sibling, 0 replies; 5+ messages in thread
From: Christian Brauner @ 2016-11-22 0:14 UTC (permalink / raw)
To: libc-alpha, serge; +Cc: stgraber
Hi,
just a friendly check whether you'd be fine with including the patch in its
current form.
Christian
On Tue, Nov 08, 2016 at 05:56:37PM +0100, Christian Brauner wrote:
> Hi,
>
> I've taken over this patch from Serge who has been informed and is CCed on this
> thread. There are no significant functional changes. As requested the following
> this have been changed:
>
> - remove obsolete comment in ttyname_r.c
> - move is_pty() to common header file and mark as static inline
>
> I hope this covers everything. :)
>
> Christian
>
> Christian Brauner (1):
> linux ttyname and ttyname_r: do not return wrong results
>
> sysdeps/unix/sysv/linux/ttyname.c | 17 +++++++++++++----
> sysdeps/unix/sysv/linux/ttyname.h | 35 +++++++++++++++++++++++++++++++++++
> sysdeps/unix/sysv/linux/ttyname_r.c | 18 ++++++++++++++----
> 3 files changed, 62 insertions(+), 8 deletions(-)
> create mode 100644 sysdeps/unix/sysv/linux/ttyname.h
>
> --
> 2.9.3
>
On Tue, Nov 08, 2016 at 05:56:38PM +0100, Christian Brauner wrote:
> If a link (say /proc/self/fd/0) pointing to a device, say /dev/pts/2, in a
> parent mount namespace is passed to ttyname, and a /dev/pts/2 exists (in a
> different devpts) in the current namespace, then it returns /dev/pts/2. But
> /dev/pts/2 is NOT the current tty, it is a different file and device.
>
> Detect this case and return ENODEV. Userspace can choose to take this as a hint
> that the fd points to a tty device but to act on the fd rather than the link.
>
> Signed-off-by: Serge Hallyn <serge@hallyn.com>
> Signed-off-by: Christian Brauner <christian.brauner@canonical.com>
> ---
> Changelog: 2016-11-08
> - remove obsolete comment in ttyname_r.c
> - move is_pty() to common header file and mark as static inline
> ---
> sysdeps/unix/sysv/linux/ttyname.c | 17 +++++++++++++----
> sysdeps/unix/sysv/linux/ttyname.h | 35 +++++++++++++++++++++++++++++++++++
> sysdeps/unix/sysv/linux/ttyname_r.c | 18 ++++++++++++++----
> 3 files changed, 62 insertions(+), 8 deletions(-)
> create mode 100644 sysdeps/unix/sysv/linux/ttyname.h
>
> diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c
> index 7a001b4..dabed22 100644
> --- a/sysdeps/unix/sysv/linux/ttyname.c
> +++ b/sysdeps/unix/sysv/linux/ttyname.c
> @@ -25,9 +25,12 @@
> #include <unistd.h>
> #include <string.h>
> #include <stdlib.h>
> +#include <sys/sysmacros.h>
>
> #include <_itoa.h>
>
> +#include "ttyname.h"
> +
> #if 0
> /* Is this used anywhere? It is not exported. */
> char *__ttyname;
> @@ -170,12 +173,18 @@ ttyname (int fd)
> #ifdef _STATBUF_ST_RDEV
> && S_ISCHR (st1.st_mode)
> && st1.st_rdev == st.st_rdev
> -#else
> - && st1.st_ino == st.st_ino
> - && st1.st_dev == st.st_dev
> #endif
> - )
> + && st1.st_ino == st.st_ino
> + && st1.st_dev == st.st_dev)
> return ttyname_buf;
> +
> + /* If the link doesn't exist, then it points to a device in another
> + namespace. */
> + if (is_pty (&st))
> + {
> + __set_errno (ENODEV);
> + return NULL;
> + }
> }
>
> if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))
> diff --git a/sysdeps/unix/sysv/linux/ttyname.h b/sysdeps/unix/sysv/linux/ttyname.h
> new file mode 100644
> index 0000000..19af6e6
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/ttyname.h
> @@ -0,0 +1,35 @@
> +/* Copyright (C) 2004-2016 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public License as
> + published by the Free Software Foundation; either version 2.1 of the
> + License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; see the file COPYING.LIB. If
> + not, see <http://www.gnu.org/licenses/>. */
> +
> +#include <unistd.h>
> +#include <sys/sysmacros.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +
> +/* Return true if this is a UNIX98 pty device, as defined in
> + linux/Documentation/devices.txt. */
> +static inline int
> +is_pty (struct stat64 *sb)
> +{
> +#ifdef _STATBUF_ST_RDEV
> + int m = major (sb->st_rdev);
> + return (136 <= m && m <= 143);
> +#else
> + return false;
> +#endif
> +}
> +
> diff --git a/sysdeps/unix/sysv/linux/ttyname_r.c b/sysdeps/unix/sysv/linux/ttyname_r.c
> index d15bc74..542114b 100644
> --- a/sysdeps/unix/sysv/linux/ttyname_r.c
> +++ b/sysdeps/unix/sysv/linux/ttyname_r.c
> @@ -25,9 +25,12 @@
> #include <unistd.h>
> #include <string.h>
> #include <stdlib.h>
> +#include <sys/sysmacros.h>
>
> #include <_itoa.h>
>
> +#include "ttyname.h"
> +
> static int getttyname_r (char *buf, size_t buflen,
> dev_t mydev, ino64_t myino, int save,
> int *dostat) internal_function;
> @@ -152,12 +155,19 @@ __ttyname_r (int fd, char *buf, size_t buflen)
> #ifdef _STATBUF_ST_RDEV
> && S_ISCHR (st1.st_mode)
> && st1.st_rdev == st.st_rdev
> -#else
> - && st1.st_ino == st.st_ino
> - && st1.st_dev == st.st_dev
> #endif
> - )
> + && st1.st_ino == st.st_ino
> + && st1.st_dev == st.st_dev)
> return 0;
> +
> + /* If the link doesn't exist, then it points to a device in another
> + * namespace.
> + */
> + if (is_pty (&st))
> + {
> + __set_errno (ENODEV);
> + return ENODEV;
> + }
> }
>
> /* Prepare the result buffer. */
> --
> 2.9.3
>
^ permalink raw reply [flat|nested] 5+ messages in thread