On Thu, 2022-11-24 at 09:17 +0100, Roberto Sassu wrote:
> On Wed, 2022-11-23 at 20:14 -0500, Mimi Zohar wrote:
> > Hi Roberto,
> >
> > On Wed, 2022-11-23 at 16:47 +0100, Roberto Sassu wrote:
> > > int security_inode_init_security(struct inode *inode, struct inode *dir,
> > > const struct qstr *qstr,
> > > const initxattrs initxattrs, void *fs_data)
> > > {
> > > - struct xattr new_xattrs[MAX_LSM_EVM_XATTR + 1];
> > > - struct xattr *lsm_xattr, *evm_xattr, *xattr;
> > > - int ret;
> > > + struct security_hook_list *P;
> > > + struct xattr *new_xattrs;
> > > + struct xattr *xattr;
> > > + int ret = -EOPNOTSUPP, num_filled_xattrs = 0;
> > >
> > > if (unlikely(IS_PRIVATE(inode)))
> > > return 0;
> > >
> > > + if (!blob_sizes.lbs_xattr)
> > > + return 0;
> > > +
> > > if (!initxattrs)
> > > return call_int_hook(inode_init_security, -EOPNOTSUPP, inode,
> > > - dir, qstr, NULL, NULL, NULL);
> > > - memset(new_xattrs, 0, sizeof(new_xattrs));
> > > - lsm_xattr = new_xattrs;
> > > - ret = call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr,
> > > - &lsm_xattr->name,
> > > - &lsm_xattr->value,
> > > - &lsm_xattr->value_len);
> > > - if (ret)
> > > + dir, qstr, NULL);
> > > + /* Allocate +1 for EVM and +1 as terminator. */
> > > + new_xattrs = kcalloc(blob_sizes.lbs_xattr + 2, sizeof(*new_xattrs),
> > > + GFP_NOFS);
> > > + if (!new_xattrs)
> > > + return -ENOMEM;
> > > +
> > > + hlist_for_each_entry(P, &security_hook_heads.inode_init_security,
> > > + list) {
> > > + ret = P->hook.inode_init_security(inode, dir, qstr, new_xattrs);
> > > + if (ret && ret != -EOPNOTSUPP)
> > > + goto out;
> > > + if (ret == -EOPNOTSUPP)
> > > + continue;
> >
> > In this context, -EOPNOTSUPP originally signified that the filesystem
> > does not support writing xattrs. Writing any xattr would fail.
> > Returning -ENODATA for no LSM xattr(s) data would seem to be more
> > appropriate than -EOPNOTSUPP.
>
> Hi Mimi
>
> I thought about adding new return values. Currently only -EOPNOTSUPP
> and -ENOMEM are expected as errors.
>
> However, changing the conventions would mean revisiting the LSMs code
> and ensuring that they follow the new conventions.
>
> I would be more in favor of not touching it.
Casey, Paul, any comment?
> >
> > > + /*
> > > + * As the number of xattrs reserved by LSMs is not directly
> > > + * available, directly use the total number blob_sizes.lbs_xattr
> > > + * to keep the code simple, while being not the most efficient
> > > + * way.
> > > + */
> > > + ret = security_check_compact_filled_xattrs(new_xattrs,
> > > + blob_sizes.lbs_xattr,
> > > + &num_filled_xattrs);
> > > + if (ret < 0) {
> > > + ret = -ENOMEM;
> > > + goto out;
> > > + }
> > > + }
> > > +
> > > + if (!num_filled_xattrs)
> > > goto out;
> > >
> > > - evm_xattr = lsm_xattr + 1;
> > > - ret = evm_inode_init_security(inode, lsm_xattr, evm_xattr);
> > > + ret = evm_inode_init_security(inode, new_xattrs,
> > > + new_xattrs + num_filled_xattrs);
> > > if (ret)
> > > goto out;
> > > ret = initxattrs(inode, new_xattrs, fs_data);
> > > out:
> > > for (xattr = new_xattrs; xattr->value != NULL; xattr++)
> > > kfree(xattr->value);
> > > + kfree(new_xattrs);
> > > return (ret == -EOPNOTSUPP) ? 0 : ret;
> > > }
> > b
>
