On Thu, Sep 08, 2011 at 03:00:58PM +0530, Aneesh Kumar K.V wrote: > On Wed, 7 Sep 2011 16:39:16 -0400, "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > > On Mon, Sep 05, 2011 at 10:55:31PM +0530, Aneesh Kumar K.V wrote: > > > From: Andreas Gruenbacher <agruen@xxxxxxxxxx> > > > > > > Normally, deleting a file requires write access to the parent directory. > > > Some permission models use a different permission on the parent > > > directory to indicate delete access. In addition, a process can have > > > per-file delete access even without delete access on the parent > > > directory. > > > > > > Introduce two new inode_permission() mask flags and use them in > > > may_delete() > > > > > > Signed-off-by: Andreas Gruenbacher <agruen@xxxxxxxxxx> > > > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > > > --- > > > fs/namei.c | 41 +++++++++++++++++++++++++++-------------- > > > include/linux/fs.h | 2 ++ > > > 2 files changed, 29 insertions(+), 14 deletions(-) > > > > > > diff --git a/fs/namei.c b/fs/namei.c > > > index d52a4cd..eacb530 100644 > > > --- a/fs/namei.c > > > +++ b/fs/namei.c > > > @@ -337,7 +337,7 @@ static inline int do_inode_permission(struct inode *inode, int mask) > > > * 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) > > > { > > > @@ -1862,7 +1862,7 @@ static inline int check_sticky(struct inode *dir, struct inode *inode) > > > return 0; > > > > > > other_userns: > > > - return !ns_capable(inode_userns(inode), CAP_FOWNER); > > > + return 1; > > > } > > > > > > /* > > > @@ -1884,30 +1884,43 @@ other_userns: > > > * 10. We don't allow removal of NFS sillyrenamed files; it's handled by > > > * nfs_async_unlink(). > > > */ > > > -static int may_delete(struct inode *dir,struct dentry *victim,int isdir) > > > +static int may_delete(struct inode *dir, struct dentry *victim, > > > + int isdir, int replace) > > > { > > > - int error; > > > + int mask, error, is_sticky; > > > + struct inode *inode = victim->d_inode; > > > > > > - if (!victim->d_inode) > > > + if (!inode) > > > return -ENOENT; > > > > > > BUG_ON(victim->d_parent->d_inode != dir); > > > audit_inode_child(victim, dir); > > > > > > - error = inode_permission(dir, MAY_WRITE | MAY_EXEC); > > > + mask = MAY_WRITE | MAY_EXEC | MAY_DELETE_CHILD; > > > + if (replace) > > > + mask |= S_ISDIR(inode->i_mode) ? > > > + MAY_CREATE_DIR : MAY_CREATE_FILE; > > > > I'm having trouble understanding this next bit: > > > > > + is_sticky = check_sticky(dir, inode); > > > + error = inode_permission(dir, mask); > > > + if ((error || is_sticky) && IS_RICHACL(inode) && > > > + !inode_permission(dir, mask & ~(MAY_WRITE | MAY_DELETE_CHILD)) && > > > + !inode_permission(inode, MAY_DELETE_SELF)) > > > + error = 0; > > > > OK, so we can ignore the lack of write or delete permissions on the > > parent if we have delete_self permissions on the child. I guess that's > > right. > > > > Why the "|| is_sticky" above? > > > > Is there some less complicated why to write this? > > we removed the ns_capable check out of check_sticky, because we don't > want to do capability check when richacl allows access. We also want to > make sure that even if mode bits allow access (inode_permission(dir, mask)) > if sticky bit is set we do additional check. Why are the two inode_permissions ANDed? The windows semantics are that you can delete if you have MAY_DELETE_CHILD *or* MAY_DELETE_SELF. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html