From patchwork Wed Nov 15 21:33:13 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 24272 Received: (qmail 18603 invoked by alias); 15 Nov 2017 21:33:29 -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 18519 invoked by uid 89); 15 Nov 2017 21:33:29 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-26.2 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_LAZY_DOMAIN_SECURITY, KB_WAM_FROM_NAME_SINGLEWORD, RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.2 spammy= X-HELO: mx1.mailbox.org From: Christian Brauner To: libc-alpha@sourceware.org Cc: lukeshu@parabola.nu Subject: [PATCH COMMITTED 4/6] linux ttyname{_r}: Make tty checks consistent Date: Wed, 15 Nov 2017 22:33:13 +0100 Message-Id: <20171115213315.7300-4-christian.brauner@ubuntu.com> In-Reply-To: <20171115213315.7300-1-christian.brauner@ubuntu.com> References: <20171115213315.7300-1-christian.brauner@ubuntu.com> From: Luke Shumaker In the ttyname and ttyname_r routines on Linux, at several points it needs to check if a given TTY is the TTY we are looking for. It used to be that this check was (to see if `maybe` is `mytty`): __xstat64(_STAT_VER, maybe_filename, &maybe) == 0 #ifdef _STATBUF_ST_RDEV && S_ISCHR(maybe.st_mode) && maybe.st_rdev == mytty.st_rdev #else && maybe.st_ino == mytty.st_ino && maybe.st_dev == mytty.st_dev #endif This check appears in several places. Then, one of the changes made in commit 15e9a4f378c8607c2ae1aa465436af4321db0e23 was to change that check to: __xstat64(_STAT_VER, maybe_filename, &maybe) == 0 #ifdef _STATBUF_ST_RDEV && S_ISCHR(maybe.st_mode) && maybe.st_rdev == mytty.st_rdev #endif && maybe.st_ino == mytty.st_ino && maybe.st_dev == mytty.st_dev That is, it made the st_ino and st_dev parts of the check happen even if we have the st_rdev member. This is an important change, because the kernel allows multiple devpts filesystem instances to be created; a device file in one devpts instance may share the same st_rdev with a file in another devpts instance, but they aren't the same file. This check appears twice in each file (ttyname.c and ttyname_r.c), once (in ttyname and __ttyname_r) to check if a candidate file found by inspecting /proc is the desired TTY, and once (in getttyname and getttyname_r) to check if a candidate file found by searching /dev is the desired TTY. However, 15e9a4f only updated the checks for files found via /proc; but the concern about collisions between devpts instances is just as valid for files found via /dev. So, update all 4 occurrences the check to be consistent with the version of the check introduced in 15e9a4f. Make it easy to keep all 4 occurrences of the check consistent by pulling it in to a static inline function, is_mytty. Reviewed-by: Christian Brauner --- ChangeLog | 7 +++++++ sysdeps/unix/sysv/linux/ttyname.c | 40 ++++++++---------------------------- sysdeps/unix/sysv/linux/ttyname.h | 12 +++++++++++ sysdeps/unix/sysv/linux/ttyname_r.c | 41 ++++++++----------------------------- 4 files changed, 36 insertions(+), 64 deletions(-) diff --git a/ChangeLog b/ChangeLog index bb960c04bd..00f388369f 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,12 @@ 2017-11-15 Luke Shumaker + [BZ #22145] + * sysdeps/unix/sysv/linux/ttyname.h (is_mytty): New function. + * sysdeps/unix/sysv/linux/ttyname.c (getttyname): Call is_mytty. + (ttyname): Likewise. + * sysdeps/unix/sysv/linux/ttyname_r.c (getttyname_r): Likewise. + (__ttyname_r): Likewise. + * sysdeps/unix/sysv/linux/ttyname.h (is_pty): Change return type from int to bool. diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c index 116cf350e5..6e97d2d455 100644 --- a/sysdeps/unix/sysv/linux/ttyname.c +++ b/sysdeps/unix/sysv/linux/ttyname.c @@ -35,14 +35,14 @@ char *__ttyname; #endif -static char *getttyname (const char *dev, dev_t mydev, - ino64_t myino, int save, int *dostat); +static char *getttyname (const char *dev, const struct stat64 *mytty, + int save, int *dostat); libc_freeres_ptr (static char *getttyname_name); static char * attribute_compat_text_section -getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat) +getttyname (const char *dev, const struct stat64 *mytty, int save, int *dostat) { static size_t namelen; struct stat64 st; @@ -63,7 +63,7 @@ getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat) *((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/'; while ((d = __readdir64 (dirstream)) != NULL) - if ((d->d_fileno == myino || *dostat) + if ((d->d_fileno == mytty->st_ino || *dostat) && strcmp (d->d_name, "stdin") && strcmp (d->d_name, "stdout") && strcmp (d->d_name, "stderr")) @@ -85,12 +85,7 @@ getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat) } memcpy (&getttyname_name[devlen], d->d_name, dlen); if (__xstat64 (_STAT_VER, getttyname_name, &st) == 0 -#ifdef _STATBUF_ST_RDEV - && S_ISCHR (st.st_mode) && st.st_rdev == mydev -#else - && d->d_fileno == myino && st.st_dev == mydev -#endif - ) + && is_mytty (mytty, &st)) { (void) __closedir (dirstream); #if 0 @@ -167,12 +162,7 @@ ttyname (int fd) /* Verify readlink result, fall back on iterating through devices. */ if (ttyname_buf[0] == '/' && __xstat64 (_STAT_VER, ttyname_buf, &st1) == 0 -#ifdef _STATBUF_ST_RDEV - && S_ISCHR (st1.st_mode) - && st1.st_rdev == st.st_rdev -#endif - && st1.st_ino == st.st_ino - && st1.st_dev == st.st_dev) + && is_mytty (&st, &st1)) return ttyname_buf; /* If the link doesn't exist, then it points to a device in another @@ -186,11 +176,7 @@ ttyname (int fd) if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode)) { -#ifdef _STATBUF_ST_RDEV - name = getttyname ("/dev/pts", st.st_rdev, st.st_ino, save, &dostat); -#else - name = getttyname ("/dev/pts", st.st_dev, st.st_ino, save, &dostat); -#endif + name = getttyname ("/dev/pts", &st, save, &dostat); } else { @@ -200,21 +186,13 @@ ttyname (int fd) if (!name && dostat != -1) { -#ifdef _STATBUF_ST_RDEV - name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat); -#else - name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat); -#endif + name = getttyname ("/dev", &st, save, &dostat); } if (!name && dostat != -1) { dostat = 1; -#ifdef _STATBUF_ST_RDEV - name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat); -#else - name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat); -#endif + name = getttyname ("/dev", &st, save, &dostat); } return name; diff --git a/sysdeps/unix/sysv/linux/ttyname.h b/sysdeps/unix/sysv/linux/ttyname.h index cdaf60fb87..48181330a9 100644 --- a/sysdeps/unix/sysv/linux/ttyname.h +++ b/sysdeps/unix/sysv/linux/ttyname.h @@ -34,3 +34,15 @@ is_pty (struct stat64 *sb) return false; #endif } + +static inline bool +is_mytty (const struct stat64 *mytty, const struct stat64 *maybe) +{ + return (maybe->st_ino == mytty->st_ino + && maybe->st_dev == mytty->st_dev +#ifdef _STATBUF_ST_RDEV + && S_ISCHR (maybe->st_mode) + && maybe->st_rdev == mytty->st_rdev +#endif + ); +} diff --git a/sysdeps/unix/sysv/linux/ttyname_r.c b/sysdeps/unix/sysv/linux/ttyname_r.c index 18f35ef2b7..58eb919c3f 100644 --- a/sysdeps/unix/sysv/linux/ttyname_r.c +++ b/sysdeps/unix/sysv/linux/ttyname_r.c @@ -31,12 +31,12 @@ #include "ttyname.h" static int getttyname_r (char *buf, size_t buflen, - dev_t mydev, ino64_t myino, int save, + const struct stat64 *mytty, int save, int *dostat); static int attribute_compat_text_section -getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino, +getttyname_r (char *buf, size_t buflen, const struct stat64 *mytty, int save, int *dostat) { struct stat64 st; @@ -52,7 +52,7 @@ getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino, } while ((d = __readdir64 (dirstream)) != NULL) - if ((d->d_fileno == myino || *dostat) + if ((d->d_fileno == mytty->st_ino || *dostat) && strcmp (d->d_name, "stdin") && strcmp (d->d_name, "stdout") && strcmp (d->d_name, "stderr")) @@ -72,12 +72,7 @@ getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino, cp[0] = '\0'; if (__xstat64 (_STAT_VER, buf, &st) == 0 -#ifdef _STATBUF_ST_RDEV - && S_ISCHR (st.st_mode) && st.st_rdev == mydev -#else - && d->d_fileno == myino && st.st_dev == mydev -#endif - ) + && is_mytty (mytty, &st)) { (void) __closedir (dirstream); __set_errno (save); @@ -151,12 +146,7 @@ __ttyname_r (int fd, char *buf, size_t buflen) /* Verify readlink result, fall back on iterating through devices. */ if (buf[0] == '/' && __xstat64 (_STAT_VER, buf, &st1) == 0 -#ifdef _STATBUF_ST_RDEV - && S_ISCHR (st1.st_mode) - && st1.st_rdev == st.st_rdev -#endif - && st1.st_ino == st.st_ino - && st1.st_dev == st.st_dev) + && is_mytty (&st, &st1)) return 0; /* If the link doesn't exist, then it points to a device in another @@ -175,13 +165,8 @@ __ttyname_r (int fd, char *buf, size_t buflen) if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode)) { -#ifdef _STATBUF_ST_RDEV - ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save, + ret = getttyname_r (buf, buflen, &st, save, &dostat); -#else - ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save, - &dostat); -#endif } else { @@ -193,26 +178,16 @@ __ttyname_r (int fd, char *buf, size_t buflen) { buf[sizeof ("/dev/") - 1] = '\0'; buflen += sizeof ("pts/") - 1; -#ifdef _STATBUF_ST_RDEV - ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save, - &dostat); -#else - ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save, + ret = getttyname_r (buf, buflen, &st, save, &dostat); -#endif } if (ret && dostat != -1) { buf[sizeof ("/dev/") - 1] = '\0'; dostat = 1; -#ifdef _STATBUF_ST_RDEV - ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, - save, &dostat); -#else - ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, + ret = getttyname_r (buf, buflen, &st, save, &dostat); -#endif } return ret;