From patchwork Tue Nov 8 16:56:38 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 17294 Received: (qmail 51171 invoked by alias); 8 Nov 2016 16:56:54 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 51125 invoked by uid 89); 8 Nov 2016 16:56:53 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=AWL, BAYES_00, RCVD_IN_DNSWL_NONE, RCVD_IN_SORBS_SPAM autolearn=no version=3.3.2 spammy=signed-off-by, signedoffby, __set_errno, act X-HELO: mail-qk0-f176.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=TkZOvLxHbQpCkNbTLHrCcpNXIj95tkl7B1MPbVRKKrk=; b=lGVg9A1NPb2heM2jD2dbfrsS51EPbMh7H5oC9uw2woykI71Dnoscr2peQQeUf8OaKe xdfOODK0Q7ArHG0pvRtlIGiFE7aNSx3HhWoS2b0K1D7iy9huAcuHBggpUy6nRrIZlGL+ qXD2/AtWvg7nnCcytX6a6/rFvMRGstH3/zoMWnTv1Cf9cZfyH/yAEKlJJqT+X/8dge/F ALZcfj6bHP8+97JJveVRYvvgNDcATUTu4NHc2PB1Lnai9xtWQvPARjhuq02d8uHanukv DaUFlerrojYX3RRPZTToFzybdYUHNcqICzo6xFTneXjtir4wwMbfYSFiVKrP0fYdtQxd PuLQ== X-Gm-Message-State: ABUngvfWrIuIDt/Ls6HbShhkEUq5tkGsG51u9M8DC9q6LN0pKS2t9SK2Mh1bpkQyj5FWQ+KL X-Received: by 10.55.4.19 with SMTP id 19mr13488261qke.18.1478624201802; Tue, 08 Nov 2016 08:56:41 -0800 (PST) From: Christian Brauner To: libc-alpha@sourceware.org, serge@hallyn.com Cc: Christian Brauner Subject: [PATCH] linux ttyname and ttyname_r: do not return wrong results Date: Tue, 8 Nov 2016 17:56:38 +0100 Message-Id: <20161108165638.21674-2-christian.brauner@canonical.com> In-Reply-To: <20161108165638.21674-1-christian.brauner@canonical.com> References: <20161108165638.21674-1-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 Signed-off-by: Christian Brauner --- 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 #include #include +#include #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 . */ + +#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 d15bc74..542114b 100644 --- a/sysdeps/unix/sysv/linux/ttyname_r.c +++ b/sysdeps/unix/sysv/linux/ttyname_r.c @@ -25,9 +25,12 @@ #include #include #include +#include #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. */