From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Gruenbacher Subject: [RFC] Apply the umask in VFS optionally (also POSIX ACL kernel infrastructure) Date: Sun, 4 Aug 2002 15:46:43 +0200 Sender: linux-fsdevel-owner@vger.kernel.org Message-ID: <200208041546.43303.agruen@suse.de> Mime-Version: 1.0 Content-Type: Multipart/Mixed; boundary="------------Boundary-00=_VLNBQNM555CR8H76RGNQ" Return-path: Received: from Hermes.suse.de (Charybdis.suse.de [213.95.15.201]) by Cantor.suse.de (Postfix) with ESMTP id A09F0142C2 for ; Sun, 4 Aug 2002 15:46:43 +0200 (MEST) To: "Linux-FSDevel" List-Id: linux-fsdevel.vger.kernel.org --------------Boundary-00=_VLNBQNM555CR8H76RGNQ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello, [This is a copy of a previous posting to linux-kernel.] The umask(2) is usually applied to the mode parameters to open(2), mkdir(= 2), creat(2) and mknod(2) in the VFS. With POSIX Access Control Lists the uma= sk must only be applied in some situations, and must have no effect in other= s. Currently there is no way for a file system to find out the original mode parameter passed to the system calls. There are two ways to solve this problem, namely, to (1) move the code th= at applies the umask into the file systems, or to (2) apply the umask in the= VFS optionally only. Option (1) is intrusive on existing file systems, and mi= ght introduce bugs, while (2) slightly complicates the VFS, but leaves file systems unaffected. I believe that (2) is the more reasonable choice in this case, so I propo= se this patch, which adds the MS_NOUMASK mount option. The flag is set by th= e file system, if the file system does not want the VFS to apply the umask, after which the file system itself is responsible for applying the umask where appropriate. Finally, I have a question related to this. We had a bug with kernel task= s, which don't have a umask associated with them (nfsd in particular). Shoul= d kernel tasks that create files be required to have a valid fs_struct (whi= ch includes the umask), or should this be special cased in file systems? Regards, Andreas. ------------------------------------------------------------------ Andreas Gruenbacher SuSE Linux AG mailto:agruen@suse.de Deutschherrnstr. 15-19 http://www.suse.de/ D-90429 Nuernberg, Germany --------------Boundary-00=_VLNBQNM555CR8H76RGNQ Content-Type: text/x-diff; charset="us-ascii"; name="linux-2.5.30-ms_noumask.diff" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="linux-2.5.30-ms_noumask.diff" Apply the umask in VFS optionally This patch adds the MS_NOUMASK mount option. This mount option is set by the file system, if the file system does not want the VFS to apply the umask. diff -Nur linux-2.5.30/include/linux/fs.h linux-2.5.30.patch/include/linux/fs.h --- linux-2.5.30/include/linux/fs.h Thu Aug 1 23:16:15 2002 +++ linux-2.5.30.patch/include/linux/fs.h Fri Aug 2 15:21:29 2002 @@ -110,6 +110,7 @@ #define MS_MOVE 8192 #define MS_REC 16384 #define MS_VERBOSE 32768 +#define MS_NOUMASK (1<<16) /* VFS does not apply the umask */ #define MS_ACTIVE (1<<30) #define MS_NOUSER (1<<31) @@ -164,6 +165,7 @@ #define IS_IMMUTABLE(inode) ((inode)->i_flags & S_IMMUTABLE) #define IS_NOATIME(inode) (__IS_FLG(inode, MS_NOATIME) || ((inode)->i_flags & S_NOATIME)) #define IS_NODIRATIME(inode) __IS_FLG(inode, MS_NODIRATIME) +#define IS_NOUMASK(inode) __IS_FLG(inode, MS_NOUMASK) #define IS_DEADDIR(inode) ((inode)->i_flags & S_DEAD) diff -Nur linux-2.5.30/fs/namei.c linux-2.5.30.patch/fs/namei.c --- linux-2.5.30/fs/namei.c Thu Aug 1 23:16:18 2002 +++ linux-2.5.30.patch/fs/namei.c Fri Aug 2 15:35:10 2002 @@ -1279,8 +1279,9 @@ /* Negative dentry, just create the file */ if (!dentry->d_inode) { - error = vfs_create(dir->d_inode, dentry, - mode & ~current->fs->umask); + if (!IS_NOUMASK(dir->d_inode)) + mode &= ~current->fs->umask; + error = vfs_create(dir->d_inode, dentry, mode); up(&dir->d_inode->i_sem); dput(nd->dentry); nd->dentry = dentry; @@ -1442,7 +1443,8 @@ dentry = lookup_create(&nd, 0); error = PTR_ERR(dentry); - mode &= ~current->fs->umask; + if (!IS_NOUMASK(nd.dentry->d_inode)) + mode &= ~current->fs->umask; if (!IS_ERR(dentry)) { switch (mode & S_IFMT) { case 0: case S_IFREG: @@ -1508,8 +1510,9 @@ dentry = lookup_create(&nd, 1); error = PTR_ERR(dentry); if (!IS_ERR(dentry)) { - error = vfs_mkdir(nd.dentry->d_inode, dentry, - mode & ~current->fs->umask); + if (!IS_NOUMASK(nd.dentry->d_inode)) + mode &= ~current->fs->umask; + error = vfs_mkdir(nd.dentry->d_inode, dentry, mode); dput(dentry); } up(&nd.dentry->d_inode->i_sem); --------------Boundary-00=_VLNBQNM555CR8H76RGNQ--