From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47374) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dmUC7-0000r8-5L for qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:15:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dmUC3-000553-7O for qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:15:51 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:50495) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dmUC2-00054A-Uq for qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:15:47 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7T0EDPc077706 for ; Mon, 28 Aug 2017 20:15:46 -0400 Received: from e14.ny.us.ibm.com (e14.ny.us.ibm.com [129.33.205.204]) by mx0a-001b2d01.pphosted.com with ESMTP id 2cmnx0yuc7-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 28 Aug 2017 20:15:45 -0400 Received: from localhost by e14.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 28 Aug 2017 20:15:44 -0400 From: Michael Roth Date: Mon, 28 Aug 2017 19:13:48 -0500 In-Reply-To: <1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com> Message-Id: <1503965694-10794-14-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 13/79] 9pfs: local: fix unlink of alien files in mapped-file mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Greg Kurz From: Greg Kurz When trying to remove a file from a directory, both created in non-mapped mode, the file remains and EBADF is returned to the guest. This is a regression introduced by commit "df4938a6651b 9pfs: local: unlinkat: don't follow symlinks" when fixing CVE-2016-9602. It changed the way we unlink the metadata file from ret = remove("$dir/.virtfs_metadata/$name"); if (ret < 0 && errno != ENOENT) { /* Error out */ } /* Ignore absence of metadata */ to fd = openat("$dir/.virtfs_metadata") unlinkat(fd, "$name") if (ret < 0 && errno != ENOENT) { /* Error out */ } /* Ignore absence of metadata */ If $dir was created in non-mapped mode, openat() fails with ENOENT and we pass -1 to unlinkat(), which fails in turn with EBADF. We just need to check the return of openat() and ignore ENOENT, in order to restore the behaviour we had with remove(). Signed-off-by: Greg Kurz Reviewed-by: Eric Blake [groug: rewrote the comments as suggested by Eric] (cherry picked from commit 6a87e7929f97b86c5823d4616fa1aa7636b2f116) Signed-off-by: Michael Roth --- hw/9pfs/9p-local.c | 34 +++++++++++++++------------------- 1 file changed, 15 insertions(+), 19 deletions(-) diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c index f3ebca4..7a0c383 100644 --- a/hw/9pfs/9p-local.c +++ b/hw/9pfs/9p-local.c @@ -957,6 +957,14 @@ static int local_unlinkat_common(FsContext *ctx, int dirfd, const char *name, if (ctx->export_flags & V9FS_SM_MAPPED_FILE) { int map_dirfd; + /* We need to remove the metadata as well: + * - the metadata directory if we're removing a directory + * - the metadata file in the parent's metadata directory + * + * If any of these are missing (ie, ENOENT) then we're probably + * trying to remove something that wasn't created in mapped-file + * mode. We just ignore the error. + */ if (flags == AT_REMOVEDIR) { int fd; @@ -964,32 +972,20 @@ static int local_unlinkat_common(FsContext *ctx, int dirfd, const char *name, if (fd == -1) { goto err_out; } - /* - * If directory remove .virtfs_metadata contained in the - * directory - */ ret = unlinkat(fd, VIRTFS_META_DIR, AT_REMOVEDIR); close_preserve_errno(fd); if (ret < 0 && errno != ENOENT) { - /* - * We didn't had the .virtfs_metadata file. May be file created - * in non-mapped mode ?. Ignore ENOENT. - */ goto err_out; } } - /* - * Now remove the name from parent directory - * .virtfs_metadata directory. - */ map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR); - ret = unlinkat(map_dirfd, name, 0); - close_preserve_errno(map_dirfd); - if (ret < 0 && errno != ENOENT) { - /* - * We didn't had the .virtfs_metadata file. May be file created - * in non-mapped mode ?. Ignore ENOENT. - */ + if (map_dirfd != -1) { + ret = unlinkat(map_dirfd, name, 0); + close_preserve_errno(map_dirfd); + if (ret < 0 && errno != ENOENT) { + goto err_out; + } + } else if (errno != ENOENT) { goto err_out; } } -- 2.7.4