Return-Path: Received: from fieldses.org ([173.255.197.46]:46518 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752625AbbH1UoP (ORCPT ); Fri, 28 Aug 2015 16:44:15 -0400 Date: Fri, 28 Aug 2015 16:44:13 -0400 To: Andreas Gruenbacher Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-api@vger.kernel.org, linux-cifs@vger.kernel.org, linux-security-module@vger.kernel.org, Andreas Gruenbacher Subject: Re: [RFC v6 03/40] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags Message-ID: <20150828204413.GB23326@fieldses.org> References: <1438689218-6921-1-git-send-email-agruenba@redhat.com> <1438689218-6921-4-git-send-email-agruenba@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1438689218-6921-4-git-send-email-agruenba@redhat.com> From: bfields@fieldses.org (J. Bruce Fields) Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, Aug 04, 2015 at 01:53:01PM +0200, Andreas Gruenbacher wrote: > Normally, deleting a file requires write and execute access to the parent > directory. With Richacls, a process with MAY_DELETE_SELF access to a file > may delete the file even without write access to the parent directory. > > To support that, pass the MAY_DELETE_CHILD mask flag to inode_permission() > when checking for delete access inside a directory, and MAY_DELETE_SELF > when checking for delete access to a file itelf. > > The MAY_DELETE_SELF permission does not override the sticky directory > check. It probably should. I guess it would basically just let the file owner delegate permission to delete your file to a non-owner? Makes sense to me to allow that. --b. > > Signed-off-by: Andreas Gruenbacher > --- > fs/namei.c | 15 +++++++++++---- > include/linux/fs.h | 2 ++ > 2 files changed, 13 insertions(+), 4 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index 3504d36..2ac759c 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -454,7 +454,7 @@ static int sb_permission(struct super_block *sb, struct inode *inode, int mask) > * changing the "normal" UIDs which are used for other things. > * > * When checking for MAY_APPEND, MAY_CREATE_FILE, MAY_CREATE_DIR, > - * MAY_WRITE must also be set in @mask. > + * MAY_DELETE_CHILD, MAY_DELETE_SELF, MAY_WRITE must also be set in @mask. > */ > int inode_permission(struct inode *inode, int mask) > { > @@ -2527,7 +2527,7 @@ static int may_delete(struct inode *dir, struct dentry *victim, > bool isdir, bool replace) > { > struct inode *inode = d_backing_inode(victim); > - int error, mask = MAY_WRITE | MAY_EXEC; > + int error, mask = MAY_EXEC; > > if (d_is_negative(victim)) > return -ENOENT; > @@ -2537,8 +2537,15 @@ static int may_delete(struct inode *dir, struct dentry *victim, > audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); > > if (replace) > - mask |= isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE; > - error = inode_permission(dir, mask); > + mask |= MAY_WRITE | (isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE); > + error = inode_permission(dir, mask | MAY_WRITE | MAY_DELETE_CHILD); > + if (error && IS_RICHACL(inode)) { > + /* Deleting is also permitted with MAY_EXEC on the directory > + * and MAY_DELETE_SELF on the inode. */ > + if (!inode_permission(inode, MAY_DELETE_SELF) && > + !inode_permission(dir, mask)) > + error = 0; > + } > if (error) > return error; > if (IS_APPEND(dir)) > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 9c44f27..abf5b0e 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -83,6 +83,8 @@ typedef void (dax_iodone_t)(struct buffer_head *bh_map, int uptodate); > #define MAY_NOT_BLOCK 0x00000080 > #define MAY_CREATE_FILE 0x00000100 > #define MAY_CREATE_DIR 0x00000200 > +#define MAY_DELETE_CHILD 0x00000400 > +#define MAY_DELETE_SELF 0x00000800 > > /* > * flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond > -- > 2.5.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html