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.
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
