From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sonata.ens-lyon.org (domu-toccata.ens-lyon.fr [140.77.166.138]) by sourceware.org (Postfix) with ESMTPS id 53B053858C62 for ; Thu, 15 Sep 2022 19:55:49 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 53B053858C62 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=ens-lyon.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=bounce.ens-lyon.org Received: from localhost (localhost [127.0.0.1]) by sonata.ens-lyon.org (Postfix) with ESMTP id 7F38F20153; Thu, 15 Sep 2022 21:55:48 +0200 (CEST) Received: from sonata.ens-lyon.org ([127.0.0.1]) by localhost (sonata.ens-lyon.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id r6HI4lyLR6z7; Thu, 15 Sep 2022 21:55:48 +0200 (CEST) Received: from begin (unknown [89.207.171.57]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by sonata.ens-lyon.org (Postfix) with ESMTPSA id 463F220151; Thu, 15 Sep 2022 21:55:48 +0200 (CEST) Received: from samy by begin with local (Exim 4.96) (envelope-from ) id 1oYuxb-001Cbf-13; Thu, 15 Sep 2022 21:55:43 +0200 From: Samuel Thibault To: libc-alpha@sourceware.org Cc: Samuel Thibault , commit-hurd@gnu.org Subject: [hurd,commited] hurd: Make readlink* just reopen the file used for stat Date: Thu, 15 Sep 2022 21:55:42 +0200 Message-Id: <20220915195542.286779-1-samuel.thibault@ens-lyon.org> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-11.2 required=5.0 tests=BAYES_00,GIT_PATCH_0,JMQ_SPF_NEUTRAL,KAM_DMARC_STATUS,RCVD_IN_DNSWL_NONE,RCVD_IN_SBL_CSS,SPF_HELO_PASS,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: 9e5c991106cb ("hurd: Fix readlink() hanging on fifo") separated opening the file for the stat call from opening the file for the read call. That however opened a small window for the file to change. Better make this atomic by reopening the file with O_READ. --- sysdeps/mach/hurd/readlink.c | 32 ++++++++++++++++++++------------ sysdeps/mach/hurd/readlinkat.c | 32 ++++++++++++++++++++------------ 2 files changed, 40 insertions(+), 24 deletions(-) diff --git a/sysdeps/mach/hurd/readlink.c b/sysdeps/mach/hurd/readlink.c index 2d75ef7725..34f132cb92 100644 --- a/sysdeps/mach/hurd/readlink.c +++ b/sysdeps/mach/hurd/readlink.c @@ -28,33 +28,41 @@ ssize_t __readlink (const char *file_name, char *buf, size_t len) { error_t err; - file_t file; + file_t file_stat; struct stat64 st; - file = __file_name_lookup (file_name, O_NOLINK, 0); - if (file == MACH_PORT_NULL) + file_stat = __file_name_lookup (file_name, O_NOLINK, 0); + if (file_stat == MACH_PORT_NULL) return -1; - err = __io_stat (file, &st); + err = __io_stat (file_stat, &st); if (! err) if (S_ISLNK (st.st_mode)) { + enum retry_type doretry; + char retryname[1024]; + file_t file; char *rbuf = buf; - __mach_port_deallocate (__mach_task_self (), file); - file = __file_name_lookup (file_name, O_READ | O_NOLINK, 0); - - err = __io_read (file, &rbuf, &len, 0, len); - if (!err && rbuf != buf) + err = __dir_lookup (file_stat, "", O_READ | O_NOLINK, 0, &doretry, retryname, &file); + if (! err && (doretry != FS_RETRY_NORMAL || retryname[0] != '\0')) + err = EGRATUITOUS; + if (! err) { - memcpy (buf, rbuf, len); - __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + err = __io_read (file, &rbuf, &len, 0, len); + if (!err && rbuf != buf) + { + memcpy (buf, rbuf, len); + __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + } + + __mach_port_deallocate (__mach_task_self (), file); } } else err = EINVAL; - __mach_port_deallocate (__mach_task_self (), file); + __mach_port_deallocate (__mach_task_self (), file_stat); if (err) return __hurd_fail (err); diff --git a/sysdeps/mach/hurd/readlinkat.c b/sysdeps/mach/hurd/readlinkat.c index 113b92b732..278a0b5b00 100644 --- a/sysdeps/mach/hurd/readlinkat.c +++ b/sysdeps/mach/hurd/readlinkat.c @@ -29,33 +29,41 @@ ssize_t readlinkat (int fd, const char *file_name, char *buf, size_t len) { error_t err; - file_t file; + file_t file_stat; struct stat64 st; - file = __file_name_lookup_at (fd, 0, file_name, O_NOLINK, 0); - if (file == MACH_PORT_NULL) + file_stat = __file_name_lookup_at (fd, 0, file_name, O_NOLINK, 0); + if (file_stat == MACH_PORT_NULL) return -1; - err = __io_stat (file, &st); + err = __io_stat (file_stat, &st); if (! err) if (S_ISLNK (st.st_mode)) { + enum retry_type doretry; + char retryname[1024]; + file_t file; char *rbuf = buf; - __mach_port_deallocate (__mach_task_self (), file); - file = __file_name_lookup_at (fd, 0, file_name, O_READ | O_NOLINK, 0); - - err = __io_read (file, &rbuf, &len, 0, len); - if (!err && rbuf != buf) + err = __dir_lookup (file_stat, "", O_READ | O_NOLINK, 0, &doretry, retryname, &file); + if (! err && (doretry != FS_RETRY_NORMAL || retryname[0] != '\0')) + err = EGRATUITOUS; + if (! err) { - memcpy (buf, rbuf, len); - __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + err = __io_read (file, &rbuf, &len, 0, len); + if (!err && rbuf != buf) + { + memcpy (buf, rbuf, len); + __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + } + + __mach_port_deallocate (__mach_task_self (), file); } } else err = EINVAL; - __mach_port_deallocate (__mach_task_self (), file); + __mach_port_deallocate (__mach_task_self (), file_stat); return err ? __hurd_fail (err) : len; } -- 2.35.1