net: sched: introduce chain object to uapi

Allow user to create, destroy, get and dump chain objects. Do that by
extending rtnl commands by the chain-specific ones. User will now be
able to explicitly create or destroy chains (so far this was done only
automatically according the filter/act needs and refcounting). Also, the
user will receive notification about any chain creation or destuction.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sch_generic.h

@@ -304,6 +304,7 @@ struct tcf_chain {
  struct tcf_block *block;
  u32 index; /* chain index */
  unsigned int refcnt;
+ bool explicitly_created;
 };
 
 struct tcf_block {

include/uapi/linux/rtnetlink.h

@@ -150,6 +150,13 @@ enum {
  RTM_NEWCACHEREPORT = 96,
 #define RTM_NEWCACHEREPORT RTM_NEWCACHEREPORT
 
+ RTM_NEWCHAIN = 100,
+#define RTM_NEWCHAIN RTM_NEWCHAIN
+ RTM_DELCHAIN,
+#define RTM_DELCHAIN RTM_DELCHAIN
+ RTM_GETCHAIN,
+#define RTM_GETCHAIN RTM_GETCHAIN
+
  __RTM_MAX,
 #define RTM_MAX (((__RTM_MAX + 3) & ~3) - 1)
 };

net/sched/cls_api.c

@@ -262,29 +262,57 @@ static void tcf_chain_hold(struct tcf_chain *chain)
  ++chain->refcnt;
 }
 
-struct tcf_chain *tcf_chain_get(struct tcf_block *block, u32 chain_index,
- bool create)
+static struct tcf_chain *tcf_chain_lookup(struct tcf_block *block,
+  u32 chain_index)
 {
  struct tcf_chain *chain;
 
  list_for_each_entry(chain, &block->chain_list, list) {
- if (chain->index == chain_index) {
- tcf_chain_hold(chain);
+ if (chain->index == chain_index)
  return chain;
- }
+ }
+ return NULL;
+}
+
+static int tc_chain_notify(struct tcf_chain *chain, struct sk_buff *oskb,
+ u32 seq, u16 flags, int event, bool unicast);
+
+struct tcf_chain *tcf_chain_get(struct tcf_block *block, u32 chain_index,
+ bool create)
+{
+ struct tcf_chain *chain = tcf_chain_lookup(block, chain_index);
+
+ if (chain) {
+ tcf_chain_hold(chain);
+ return chain;
  }
 
- return create ? tcf_chain_create(block, chain_index) : NULL;
+ if (!create)
+ return NULL;
+ chain = tcf_chain_create(block, chain_index);
+ if (!chain)
+ return NULL;
+ tc_chain_notify(chain, NULL, 0, NLM_F_CREATE | NLM_F_EXCL,
+ RTM_NEWCHAIN, false);
+ return chain;
 }
 EXPORT_SYMBOL(tcf_chain_get);
 
 void tcf_chain_put(struct tcf_chain *chain)
 {
- if (--chain->refcnt == 0)
+ if (--chain->refcnt == 0) {
+ tc_chain_notify(chain, NULL, 0, 0, RTM_DELCHAIN, false);
  tcf_chain_destroy(chain);
+ }
 }
 EXPORT_SYMBOL(tcf_chain_put);
 
+static void tcf_chain_put_explicitly_created(struct tcf_chain *chain)
+{
+ if (chain->explicitly_created)
+ tcf_chain_put(chain);
+}
+
 static bool tcf_block_offload_in_use(struct tcf_block *block)
 {
  return block->offloadcnt;
@@ -694,8 +722,10 @@ void tcf_block_put_ext(struct tcf_block *block, struct Qdisc *q,
 
  if (block->refcnt == 1) {
  /* At this point, all the chains should have refcnt >= 1. */
- list_for_each_entry_safe(chain, tmp, &block->chain_list, list)
+ list_for_each_entry_safe(chain, tmp, &block->chain_list, list) {
+ tcf_chain_put_explicitly_created(chain);
  tcf_chain_put(chain);
+ }
 
  block->refcnt--;
  if (list_empty(&block->chain_list))
@@ -1609,6 +1639,264 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
  return skb->len;
 }
 
+static int tc_chain_fill_node(struct tcf_chain *chain, struct net *net,
+ struct sk_buff *skb, struct tcf_block *block,
+ u32 portid, u32 seq, u16 flags, int event)
+{
+ unsigned char *b = skb_tail_pointer(skb);
+ struct nlmsghdr *nlh;
+ struct tcmsg *tcm;
+
+ nlh = nlmsg_put(skb, portid, seq, event, sizeof(*tcm), flags);
+ if (!nlh)
+ goto out_nlmsg_trim;
+ tcm = nlmsg_data(nlh);
+ tcm->tcm_family = AF_UNSPEC;
+ tcm->tcm__pad1 = 0;
+ tcm->tcm__pad2 = 0;
+ tcm->tcm_handle = 0;
+ if (block->q) {
+ tcm->tcm_ifindex = qdisc_dev(block->q)->ifindex;
+ tcm->tcm_parent = block->q->handle;
+ } else {
+ tcm->tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
+ tcm->tcm_block_index = block->index;
+ }
+
+ if (nla_put_u32(skb, TCA_CHAIN, chain->index))
+ goto nla_put_failure;
+
+ nlh->nlmsg_len = skb_tail_pointer(skb) - b;
+ return skb->len;
+
+out_nlmsg_trim:
+nla_put_failure:
+ nlmsg_trim(skb, b);
+ return -EMSGSIZE;
+}
+
+static int tc_chain_notify(struct tcf_chain *chain, struct sk_buff *oskb,
+ u32 seq, u16 flags, int event, bool unicast)
+{
+ u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
+ struct tcf_block *block = chain->block;
+ struct net *net = block->net;
+ struct sk_buff *skb;
+
+ skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
+ if (!skb)
+ return -ENOBUFS;
+
+ if (tc_chain_fill_node(chain, net, skb, block, portid,
+ seq, flags, event) <= 0) {
+ kfree_skb(skb);
+ return -EINVAL;
+ }
+
+ if (unicast)
+ return netlink_unicast(net->rtnl, skb, portid, MSG_DONTWAIT);
+
+ return rtnetlink_send(skb, net, portid, RTNLGRP_TC, flags & NLM_F_ECHO);
+}
+
+/* Add/delete/get a chain */
+
+static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n,
+ struct netlink_ext_ack *extack)
+{
+ struct net *net = sock_net(skb->sk);
+ struct nlattr *tca[TCA_MAX + 1];
+ struct tcmsg *t;
+ u32 parent;
+ u32 chain_index;
+ struct Qdisc *q = NULL;
+ struct tcf_chain *chain = NULL;
+ struct tcf_block *block;
+ unsigned long cl;
+ int err;
+
+ if (n->nlmsg_type != RTM_GETCHAIN &&
+ !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
+ return -EPERM;
+
+replay:
+ err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL, extack);
+ if (err < 0)
+ return err;
+
+ t = nlmsg_data(n);
+ parent = t->tcm_parent;
+ cl = 0;
+
+ block = tcf_block_find(net, &q, &parent, &cl,
+ t->tcm_ifindex, t->tcm_block_index, extack);
+ if (IS_ERR(block))
+ return PTR_ERR(block);
+
+ chain_index = tca[TCA_CHAIN] ? nla_get_u32(tca[TCA_CHAIN]) : 0;
+ if (chain_index > TC_ACT_EXT_VAL_MASK) {
+ NL_SET_ERR_MSG(extack, "Specified chain index exceeds upper limit");
+ return -EINVAL;
+ }
+ chain = tcf_chain_lookup(block, chain_index);
+ if (n->nlmsg_type == RTM_NEWCHAIN) {
+ if (chain) {
+ NL_SET_ERR_MSG(extack, "Filter chain already exists");
+ return -EEXIST;
+ }
+ if (!(n->nlmsg_flags & NLM_F_CREATE)) {
+ NL_SET_ERR_MSG(extack, "Need both RTM_NEWCHAIN and NLM_F_CREATE to create a new chain");
+ return -ENOENT;
+ }
+ chain = tcf_chain_create(block, chain_index);
+ if (!chain) {
+ NL_SET_ERR_MSG(extack, "Failed to create filter chain");
+ return -ENOMEM;
+ }
+ } else {
+ if (!chain) {
+ NL_SET_ERR_MSG(extack, "Cannot find specified filter chain");
+ return -EINVAL;
+ }
+ tcf_chain_hold(chain);
+ }
+
+ switch (n->nlmsg_type) {
+ case RTM_NEWCHAIN:
+ /* In case the chain was successfully added, take a reference
+ * to the chain. This ensures that an empty chain
+ * does not disappear at the end of this function.
+ */
+ tcf_chain_hold(chain);
+ chain->explicitly_created = true;
+ tc_chain_notify(chain, NULL, 0, NLM_F_CREATE | NLM_F_EXCL,
+ RTM_NEWCHAIN, false);
+ break;
+ case RTM_DELCHAIN:
+ /* Flush the chain first as the user requested chain removal. */
+ tcf_chain_flush(chain);
+ /* In case the chain was successfully deleted, put a reference
+ * to the chain previously taken during addition.
+ */
+ tcf_chain_put_explicitly_created(chain);
+ break;
+ case RTM_GETCHAIN:
+ break;
+ err = tc_chain_notify(chain, skb, n->nlmsg_seq,
+ n->nlmsg_seq, n->nlmsg_type, true);
+ if (err < 0)
+ NL_SET_ERR_MSG(extack, "Failed to send chain notify message");
+ break;
+ default:
+ err = -EOPNOTSUPP;
+ NL_SET_ERR_MSG(extack, "Unsupported message type");
+ goto errout;
+ }
+
+errout:
+ tcf_chain_put(chain);
+ if (err == -EAGAIN)
+ /* Replay the request. */
+ goto replay;
+ return err;
+}
+
+/* called with RTNL */
+static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb)
+{
+ struct net *net = sock_net(skb->sk);
+ struct nlattr *tca[TCA_MAX + 1];
+ struct Qdisc *q = NULL;
+ struct tcf_block *block;
+ struct tcf_chain *chain;
+ struct tcmsg *tcm = nlmsg_data(cb->nlh);
+ long index_start;
+ long index;
+ u32 parent;
+ int err;
+
+ if (nlmsg_len(cb->nlh) < sizeof(*tcm))
+ return skb->len;
+
+ err = nlmsg_parse(cb->nlh, sizeof(*tcm), tca, TCA_MAX, NULL, NULL);
+ if (err)
+ return err;
+
+ if (tcm->tcm_ifindex == TCM_IFINDEX_MAGIC_BLOCK) {
+ block = tcf_block_lookup(net, tcm->tcm_block_index);
+ if (!block)
+ goto out;
+ /* If we work with block index, q is NULL and parent value
+ * will never be used in the following code. The check
+ * in tcf_fill_node prevents it. However, compiler does not
+ * see that far, so set parent to zero to silence the warning
+ * about parent being uninitialized.
+ */
+ parent = 0;
+ } else {
+ const struct Qdisc_class_ops *cops;
+ struct net_device *dev;
+ unsigned long cl = 0;
+
+ dev = __dev_get_by_index(net, tcm->tcm_ifindex);
+ if (!dev)
+ return skb->len;
+
+ parent = tcm->tcm_parent;
+ if (!parent) {
+ q = dev->qdisc;
+ parent = q->handle;
+ } else {
+ q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));
+ }
+ if (!q)
+ goto out;
+ cops = q->ops->cl_ops;
+ if (!cops)
+ goto out;
+ if (!cops->tcf_block)
+ goto out;
+ if (TC_H_MIN(tcm->tcm_parent)) {
+ cl = cops->find(q, tcm->tcm_parent);
+ if (cl == 0)
+ goto out;
+ }
+ block = cops->tcf_block(q, cl, NULL);
+ if (!block)
+ goto out;
+ if (tcf_block_shared(block))
+ q = NULL;
+ }
+
+ index_start = cb->args[0];
+ index = 0;
+
+ list_for_each_entry(chain, &block->chain_list, list) {
+ if ((tca[TCA_CHAIN] &&
+ nla_get_u32(tca[TCA_CHAIN]) != chain->index))
+ continue;
+ if (index < index_start) {
+ index++;
+ continue;
+ }
+ err = tc_chain_fill_node(chain, net, skb, block,
+ NETLINK_CB(cb->skb).portid,
+ cb->nlh->nlmsg_seq, NLM_F_MULTI,
+ RTM_NEWCHAIN);
+ if (err <= 0)
+ break;
+ index++;
+ }
+
+ cb->args[0] = index;
+
+out:
+ /* If we did no progress, the error (EMSGSIZE) is real */
+ if (skb->len == 0 && err)
+ return err;
+ return skb->len;
+}
+
 void tcf_exts_destroy(struct tcf_exts *exts)
 {
 #ifdef CONFIG_NET_CLS_ACT
@@ -1825,6 +2113,10 @@ static int __init tc_filter_init(void)
  rtnl_register(PF_UNSPEC, RTM_DELTFILTER, tc_del_tfilter, NULL, 0);
  rtnl_register(PF_UNSPEC, RTM_GETTFILTER, tc_get_tfilter,
  tc_dump_tfilter, 0);
+ rtnl_register(PF_UNSPEC, RTM_NEWCHAIN, tc_ctl_chain, NULL, 0);
+ rtnl_register(PF_UNSPEC, RTM_DELCHAIN, tc_ctl_chain, NULL, 0);
+ rtnl_register(PF_UNSPEC, RTM_GETCHAIN, tc_ctl_chain,
+ tc_dump_chain, 0);
 
  return 0;
 

security/selinux/nlmsgtab.c

@@ -159,7 +159,7 @@ int selinux_nlmsg_lookup(u16 sclass, u16 nlmsg_type, u32 *perm)
  switch (sclass) {
  case SECCLASS_NETLINK_ROUTE_SOCKET:
  /* RTM_MAX always point to RTM_SETxxxx, ie RTM_NEWxxx + 3 */
- BUILD_BUG_ON(RTM_MAX != (RTM_NEWCACHEREPORT + 3));
+ BUILD_BUG_ON(RTM_MAX != (RTM_NEWCHAIN + 3));
  err = nlmsg_perm(nlmsg_type, perm, nlmsg_route_perms,
  sizeof(nlmsg_route_perms));
  break;