From 15e9a4f378c8607c2ae1aa465436af4321db0e23 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Fri, 27 Jan 2017 15:59:59 +0100 Subject: [PATCH] linux ttyname and ttyname_r: do not return wrong results 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 Signed-off-by: Christian Brauner --- ChangeLog | 12 ++++++++++ sysdeps/unix/sysv/linux/ttyname.c | 16 ++++++++++---- sysdeps/unix/sysv/linux/ttyname.h | 34 +++++++++++++++++++++++++++++ sysdeps/unix/sysv/linux/ttyname_r.c | 17 +++++++++++---- 4 files changed, 71 insertions(+), 8 deletions(-) create mode 100644 sysdeps/unix/sysv/linux/ttyname.h diff --git a/ChangeLog b/ChangeLog index ce823aec0f..e732c7d46b 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,15 @@ +2017-03-19 Christian Brauner + + * sysdeps/unix/sysv/linux/ttyname.h: New file. + * sysdeps/unix/sysv/linux/ttyname.c: Include "ttyname.h". + (ttyname) [!_STATBUF_ST_RDEV]: Make code unconditional. + Call is_pty when the link does not exist or does not match, fail + with ENODEV when it returns true. + * sysdeps/unix/sysv/linux/ttyname_r.c: Include "ttyname.h". + (__ttyname_r) [!_STATBUF_ST_RDEV]: Make code unconditional. + Call is_pty when the link does not exist or does not match, fail + with ENODEV when it returns true. + 2017-03-18 Joseph Myers [BZ #16437] diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c index e2686b5a23..5909cb765f 100644 --- a/sysdeps/unix/sysv/linux/ttyname.c +++ b/sysdeps/unix/sysv/linux/ttyname.c @@ -28,6 +28,8 @@ #include <_itoa.h> +#include "ttyname.h" + #if 0 /* Is this used anywhere? It is not exported. */ char *__ttyname; @@ -170,12 +172,18 @@ 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 0000000000..2e415e4e9c --- /dev/null +++ b/sysdeps/unix/sysv/linux/ttyname.h @@ -0,0 +1,34 @@ +/* Copyright (C) 2016-2017 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 . */ + +#include +#include +#include +#include + +/* 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 10b170a8b5..dc863526ba 100644 --- a/sysdeps/unix/sysv/linux/ttyname_r.c +++ b/sysdeps/unix/sysv/linux/ttyname_r.c @@ -28,6 +28,8 @@ #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 +154,19 @@ __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. */ -- 2.43.5