From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40413) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dFhOg-0007H7-0C for qemu-devel@nongnu.org; Tue, 30 May 2017 09:41:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dFhOa-00021d-UQ for qemu-devel@nongnu.org; Tue, 30 May 2017 09:41:18 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:57874) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dFhOa-00021F-Ki for qemu-devel@nongnu.org; Tue, 30 May 2017 09:41:12 -0400 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v4UDcdZZ038338 for ; Tue, 30 May 2017 09:41:11 -0400 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 2as67h9q5d-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 30 May 2017 09:41:10 -0400 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 30 May 2017 14:41:08 +0100 From: Greg Kurz Date: Tue, 30 May 2017 15:40:33 +0200 In-Reply-To: <1496151640-29919-1-git-send-email-groug@kaod.org> References: <1496151640-29919-1-git-send-email-groug@kaod.org> Message-Id: <1496151640-29919-5-git-send-email-groug@kaod.org> Subject: [Qemu-devel] [PULL v2 04/11] 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: Peter Maydell , Stefan Hajnoczi , 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] --- 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 a2486566afb7..226234d38642 100644 --- a/hw/9pfs/9p-local.c +++ b/hw/9pfs/9p-local.c @@ -992,6 +992,14 @@ 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; @@ -999,32 +1007,20 @@ 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; } } -- 2.7.5