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.
Thanks
Roberto
> thanks,
>
> Mimi
>
> > + /*
> > + * 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
