From: Jeff Layton Subject: Re: [PATCH -V4 08/11] vfs: Add new file and directory create permission flags Date: Fri, 24 Sep 2010 11:54:23 -0400 Message-ID: <20100924115423.530813c3@tlielax.poochiereds.net> References: <1285332494-12756-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1285332494-12756-9-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: sfrench@us.ibm.com, ffilz@us.ibm.com, agruen@suse.de, adilger@sun.com, sandeen@redhat.com, tytso@mit.edu, bfields@citi.umich.edu, linux-fsdevel@vger.kernel.org, nfsv4@linux-nfs.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: "Aneesh Kumar K.V" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:50498 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752016Ab0IXPye (ORCPT ); Fri, 24 Sep 2010 11:54:34 -0400 In-Reply-To: <1285332494-12756-9-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, 24 Sep 2010 18:18:11 +0530 "Aneesh Kumar K.V" wrote: > From: Andreas Gruenbacher > > Some permission models distinguish between the permission to create a > non-directory and a directory. Pass this information down to > inode_permission() as mask flags > > Signed-off-by: Andreas Gruenbacher > Signed-off-by: Aneesh Kumar K.V > --- > fs/namei.c | 21 ++++++++++++--------- > include/linux/fs.h | 2 ++ > 2 files changed, 14 insertions(+), 9 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index b0b8a71..ed786b2 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -253,7 +253,8 @@ int generic_permission(struct inode *inode, int mask, > * for filesystem access without changing the "normal" uids which > * are used for other things. > * > - * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. > + * When checking for MAY_APPEND, MAY_CREATE_FILE, MAY_CREATE_DIR, > + * MAY_WRITE must also be set in @mask. > */ > int inode_permission(struct inode *inode, int mask) > { > @@ -1337,13 +1338,15 @@ static int may_delete(struct inode *dir,struct dentry *victim,int isdir) > * 3. We should have write and exec permissions on dir > * 4. We can't do it if dir is immutable (done in permission()) > */ > -static inline int may_create(struct inode *dir, struct dentry *child) > +static inline int may_create(struct inode *dir, struct dentry *child, int isdir) ^^^^^ nit: maybe saner as a bool? > { > + int mask = isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE; > + > if (child->d_inode) > return -EEXIST; > if (IS_DEADDIR(dir)) > return -ENOENT; > - return inode_permission(dir, MAY_WRITE | MAY_EXEC); > + return inode_permission(dir, MAY_WRITE | MAY_EXEC | mask); > } > > /* > @@ -1391,7 +1394,7 @@ void unlock_rename(struct dentry *p1, struct dentry *p2) > int vfs_create(struct inode *dir, struct dentry *dentry, int mode, > struct nameidata *nd) > { > - int error = may_create(dir, dentry); > + int error = may_create(dir, dentry, 0); > > if (error) > return error; > @@ -1953,7 +1956,7 @@ EXPORT_SYMBOL_GPL(lookup_create); > > int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) > { > - int error = may_create(dir, dentry); > + int error = may_create(dir, dentry, 0); > > if (error) > return error; > @@ -2057,7 +2060,7 @@ SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) > > int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) > { > - int error = may_create(dir, dentry); > + int error = may_create(dir, dentry, 1); > > if (error) > return error; > @@ -2342,7 +2345,7 @@ SYSCALL_DEFINE1(unlink, const char __user *, pathname) > > int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) > { > - int error = may_create(dir, dentry); > + int error = may_create(dir, dentry, 0); > > if (error) > return error; > @@ -2415,7 +2418,7 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de > if (!inode) > return -ENOENT; > > - error = may_create(dir, new_dentry); > + error = may_create(dir, new_dentry, S_ISDIR(inode->i_mode)); ^^^^ this is a little scary, but even if it's a directory, it'll get kicked out in a later check. Would it be clearer to move up the S_ISDIR() check in this function and then pass this in as false? > if (error) > return error; > > @@ -2631,7 +2634,7 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, > return error; > > if (!new_dentry->d_inode) > - error = may_create(new_dir, new_dentry); > + error = may_create(new_dir, new_dentry, is_dir); > else > error = may_delete(new_dir, new_dentry, is_dir); > if (error) > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 26fc8ae..5dc1ebd 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -55,6 +55,8 @@ struct inodes_stat_t { > #define MAY_ACCESS 16 > #define MAY_OPEN 32 > #define MAY_CHDIR 64 > +#define MAY_CREATE_FILE 128 > +#define MAY_CREATE_DIR 256 > > /* > * flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond -- Jeff Layton