From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54030) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cfp8m-0006QZ-K5 for qemu-devel@nongnu.org; Mon, 20 Feb 2017 09:40:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cfp8j-0003eT-8X for qemu-devel@nongnu.org; Mon, 20 Feb 2017 09:40:36 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:37502 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cfp8j-0003eL-1Z for qemu-devel@nongnu.org; Mon, 20 Feb 2017 09:40:33 -0500 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v1KEcs87126955 for ; Mon, 20 Feb 2017 09:40:32 -0500 Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) by mx0b-001b2d01.pphosted.com with ESMTP id 28r012ptp2-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 20 Feb 2017 09:40:31 -0500 Received: from localhost by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 20 Feb 2017 07:40:31 -0700 From: Greg Kurz Date: Mon, 20 Feb 2017 15:40:23 +0100 In-Reply-To: <148760155821.31154.13876757160410915057.stgit@bahia.lan> References: <148760155821.31154.13876757160410915057.stgit@bahia.lan> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <148760162344.31154.691252878759862885.stgit@bahia.lan> Subject: [Qemu-devel] [PATCH 08/29] 9pfs: local: lgetxattr: don't follow symlinks List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: "Daniel P. Berrange" , Jann Horn , Prasad J Pandit , Greg Kurz , "Aneesh Kumar K.V" , Stefan Hajnoczi The local_lgetxattr() callback is vulnerable to symlink attacks because it calls lgetxattr() which follows symbolic links in all path elements but the rightmost one. This patch converts local_lgetxattr() to rely on opendir_nofollow() and fgetxattrat_nofollow() instead. This partly fixes CVE-2016-9602. Signed-off-by: Greg Kurz --- hw/9pfs/9p-posix-acl.c | 16 ++-------------- hw/9pfs/9p-xattr-user.c | 8 +------- hw/9pfs/9p-xattr.c | 8 +------- 3 files changed, 4 insertions(+), 28 deletions(-) diff --git a/hw/9pfs/9p-posix-acl.c b/hw/9pfs/9p-posix-acl.c index ec003181cd33..9435e27a368c 100644 --- a/hw/9pfs/9p-posix-acl.c +++ b/hw/9pfs/9p-posix-acl.c @@ -25,13 +25,7 @@ static ssize_t mp_pacl_getxattr(FsContext *ctx, const char *path, const char *name, void *value, size_t size) { - char *buffer; - ssize_t ret; - - buffer = rpath(ctx, path); - ret = lgetxattr(buffer, MAP_ACL_ACCESS, value, size); - g_free(buffer); - return ret; + return local_getxattr_nofollow(ctx, path, MAP_ACL_ACCESS, value, size); } static ssize_t mp_pacl_listxattr(FsContext *ctx, const char *path, @@ -89,13 +83,7 @@ static int mp_pacl_removexattr(FsContext *ctx, static ssize_t mp_dacl_getxattr(FsContext *ctx, const char *path, const char *name, void *value, size_t size) { - char *buffer; - ssize_t ret; - - buffer = rpath(ctx, path); - ret = lgetxattr(buffer, MAP_ACL_DEFAULT, value, size); - g_free(buffer); - return ret; + return local_getxattr_nofollow(ctx, path, MAP_ACL_DEFAULT, value, size); } static ssize_t mp_dacl_listxattr(FsContext *ctx, const char *path, diff --git a/hw/9pfs/9p-xattr-user.c b/hw/9pfs/9p-xattr-user.c index f87530c8b526..4071fbc4c086 100644 --- a/hw/9pfs/9p-xattr-user.c +++ b/hw/9pfs/9p-xattr-user.c @@ -20,9 +20,6 @@ static ssize_t mp_user_getxattr(FsContext *ctx, const char *path, const char *name, void *value, size_t size) { - char *buffer; - ssize_t ret; - if (strncmp(name, "user.virtfs.", 12) == 0) { /* * Don't allow fetch of user.virtfs namesapce @@ -31,10 +28,7 @@ static ssize_t mp_user_getxattr(FsContext *ctx, const char *path, errno = ENOATTR; return -1; } - buffer = rpath(ctx, path); - ret = lgetxattr(buffer, name, value, size); - g_free(buffer); - return ret; + return local_getxattr_nofollow(ctx, path, name, value, size); } static ssize_t mp_user_listxattr(FsContext *ctx, const char *path, diff --git a/hw/9pfs/9p-xattr.c b/hw/9pfs/9p-xattr.c index 62993624ff64..4c3c0046bd47 100644 --- a/hw/9pfs/9p-xattr.c +++ b/hw/9pfs/9p-xattr.c @@ -304,13 +304,7 @@ int v9fs_remove_xattr(FsContext *ctx, ssize_t pt_getxattr(FsContext *ctx, const char *path, const char *name, void *value, size_t size) { - char *buffer; - ssize_t ret; - - buffer = rpath(ctx, path); - ret = lgetxattr(buffer, name, value, size); - g_free(buffer); - return ret; + return local_getxattr_nofollow(ctx, path, name, value, size); } int pt_setxattr(FsContext *ctx, const char *path, const char *name, void *value,