| Message ID | 20161108165638.21674-2-christian.brauner@canonical.com |
|---|---|
| State | New |
| Headers | show |
Quoting Christian Brauner (christian.brauner@canonical.com): > 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> Thanks ! > --- > 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
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> This is probably a leftover from previous editions and could be safely removed. [...] > 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> Likewise. Besides that, it looks good.
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. */