--- /dev/null
+/*
+ * Copyright 2017 Intel Deutschland GmbH
+ */
+#include <net/genetlink.h>
+#include <net/sock.h>
+
+enum nlmsgerr_attrs {
+ NLMSGERR_ATTR_UNUSED,
+ NLMSGERR_ATTR_MSG,
+ NLMSGERR_ATTR_OFFS,
+ NLMSGERR_ATTR_COOKIE,
+ __NLMSGERR_ATTR_MAX,
+ NLMSGERR_ATTR_MAX = __NLMSGERR_ATTR_MAX - 1
+};
+
+#define NLM_F_CAPPED 0x100 /* request was capped */
+#define NLM_F_ACK_TLVS 0x200 /* extended ACK TVLs were included */
+
+struct bp_extack_genl_family {
+ struct genl_family family;
+ struct genl_family *real_family;
+
+ struct genl_ops ops[];
+};
+
+static const struct nla_policy extack_dummy_policy[1] = {};
+
+static struct bp_extack_genl_family *get_copy(const struct genl_ops *op)
+{
+ do {
+ op--;
+ } while (op->policy != extack_dummy_policy);
+
+ return container_of(op, struct bp_extack_genl_family, ops[0]);
+}
+
+static int extack_pre_doit(const struct genl_ops *ops,
+ struct sk_buff *skb,
+ struct genl_info *info)
+{
+ struct netlink_ext_ack *extack = kzalloc(sizeof(*extack), GFP_KERNEL);
+ struct bp_extack_genl_family *copy = get_copy(ops);
+ const struct genl_ops *real_ops;
+ int err;
+
+ info->userhdr = extack;
+
+ if (!extack) {
+ info->userhdr = ERR_PTR(-ENOMEM);
+ return -ENOMEM;
+ }
+
+ real_ops = ©->real_family->ops[ops - ©->ops[1]];
+ extack->__bp_genl_real_ops = real_ops;
+
+ if (copy->real_family->pre_doit)
+ err = copy->real_family->pre_doit(real_ops, skb, info);
+ else
+ err = 0;
+
+ if (err) {
+ info->userhdr = ERR_PTR(err);
+ kfree(extack);
+ }
+
+ return err;
+}
+
+static void extack_netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+ int err, const struct netlink_ext_ack *extack)
+{
+ struct sk_buff *skb;
+ struct nlmsghdr *rep;
+ struct nlmsgerr *errmsg;
+ size_t payload = sizeof(*errmsg);
+ size_t tlvlen = 0;
+ unsigned int flags = 0;
+ /* backports assumes everyone supports this - libnl does so it's true */
+ bool nlk_has_extack = true;
+
+ /* Error messages get the original request appened, unless the user
+ * requests to cap the error message, and get extra error data if
+ * requested.
+ * (ignored in backports)
+ */
+ if (err) {
+ if (1)
+ payload += nlmsg_len(nlh);
+ else
+ flags |= NLM_F_CAPPED;
+ if (nlk_has_extack && extack) {
+ if (extack->_msg)
+ tlvlen += nla_total_size(strlen(extack->_msg) + 1);
+ if (extack->bad_attr)
+ tlvlen += nla_total_size(sizeof(u32));
+ }
+ } else {
+ flags |= NLM_F_CAPPED;
+
+ if (nlk_has_extack && extack && extack->cookie_len)
+ tlvlen += nla_total_size(extack->cookie_len);
+ }
+
+ if (tlvlen)
+ flags |= NLM_F_ACK_TLVS;
+
+ skb = nlmsg_new(payload + tlvlen, GFP_KERNEL);
+ if (!skb) {
+ NETLINK_CB(in_skb).sk->sk_err = ENOBUFS;
+ NETLINK_CB(in_skb).sk->sk_error_report(NETLINK_CB(in_skb).sk);
+ return;
+ }
+
+ rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
+ NLMSG_ERROR, payload, flags);
+ errmsg = nlmsg_data(rep);
+ errmsg->error = err;
+ memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
+
+ if (nlk_has_extack && extack) {
+ if (err) {
+ if (extack->_msg)
+ WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
+ extack->_msg));
+ if (extack->bad_attr &&
+ !WARN_ON((u8 *)extack->bad_attr < in_skb->data ||
+ (u8 *)extack->bad_attr >= in_skb->data +
+ in_skb->len))
+ WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
+ (u8 *)extack->bad_attr -
+ in_skb->data));
+ } else {
+ if (extack->cookie_len)
+ WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
+ extack->cookie_len,
+ extack->cookie));
+ }
+ }
+
+ nlmsg_end(skb, rep);
+
+ netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid, MSG_DONTWAIT);
+}
+
+static int extack_doit(struct sk_buff *skb, struct genl_info *info)
+{
+ const struct genl_ops *real_ops;
+ int err;
+
+ /* older kernels have a bug here */
+ if (IS_ERR(info->userhdr)) {
+ extack_netlink_ack(skb, info->nlhdr,
+ PTR_ERR(info->userhdr),
+ genl_info_extack(info));
+ goto out;
+ }
+
+ real_ops = genl_info_extack(info)->__bp_genl_real_ops;
+ err = real_ops->doit(skb, info);
+
+ if (err == -EINTR)
+ return err;
+
+ if (info->nlhdr->nlmsg_flags & NLM_F_ACK || err)
+ extack_netlink_ack(skb, info->nlhdr, err,
+ genl_info_extack(info));
+
+out:
+ /* suppress sending ACK from normal netlink code */
+ info->nlhdr->nlmsg_flags &= ~NLM_F_ACK;
+ return 0;
+}
+
+static void extack_post_doit(const struct genl_ops *ops,
+ struct sk_buff *skb,
+ struct genl_info *info)
+{
+ void (*post_doit)(const struct genl_ops *ops,
+ struct sk_buff *skb,
+ struct genl_info *info);
+
+ post_doit = get_copy(ops)->real_family->post_doit;
+
+ if (post_doit)
+ post_doit(ops, skb, info);
+ kfree(info->userhdr);
+}
+
+int bp_extack_genl_register_family(struct genl_family *family)
+{
+ unsigned int size = sizeof(struct bp_extack_genl_family) +
+ sizeof(family->ops[0]) * (family->n_ops + 1);
+ struct bp_extack_genl_family *copy;
+ int i, err;
+
+ copy = kzalloc(size, GFP_KERNEL);
+ if (!copy)
+ return -ENOMEM;
+
+ copy->family = *family;
+ copy->real_family = family;
+ copy->family.ops = ©->ops[1];
+
+ for (i = 0; i < family->n_ops; i++) {
+ copy->ops[i + 1] = family->ops[i];
+ if (family->ops[i].doit)
+ copy->ops[i + 1].doit = extack_doit;
+ }
+
+ copy->ops[0].policy = extack_dummy_policy;
+
+ copy->family.pre_doit = extack_pre_doit;
+ copy->family.post_doit = extack_post_doit;
+
+ /*
+ * store in attrbuf, so that even if we re-register the family
+ * the data will be overwritten and we don't overwrite data
+ * that's used again later...
+ */
+ family->attrbuf = (void *)copy;
+
+ err = __real_bp_extack_genl_register_family(©->family);
+ if (err)
+ kfree(copy);
+ return err;
+}
+EXPORT_SYMBOL_GPL(bp_extack_genl_register_family);
+
+int bp_extack_genl_unregister_family(struct genl_family *family)
+{
+ struct bp_extack_genl_family *copy = (void *)family->attrbuf;
+ int err;
+
+ if (!copy)
+ return -ENOENT;
+
+ err = __real_bp_extack_genl_unregister_family(©->family);
+ WARN_ON(err);
+ kfree(copy);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(bp_extack_genl_unregister_family);
projects / openwrt / staging / blogic.git / commitdiff