1 files changed, 524 insertions, 0 deletions

diff --git a/net/sched/ematch.c b/net/sched/ematch.c
new file mode 100644
index 00000000000..ebfe2e7d21b
--- /dev/null
+++ b/net/sched/ematch.c
@@ -0,0 +1,524 @@
+/*
+ * net/sched/ematch.c		Extended Match API
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ * Authors:	Thomas Graf <tgraf@suug.ch>
+ *
+ * ==========================================================================
+ *
+ * An extended match (ematch) is a small classification tool not worth
+ * writing a full classifier for. Ematches can be interconnected to form
+ * a logic expression and get attached to classifiers to extend their
+ * functionatlity.
+ *
+ * The userspace part transforms the logic expressions into an array
+ * consisting of multiple sequences of interconnected ematches separated
+ * by markers. Precedence is implemented by a special ematch kind
+ * referencing a sequence beyond the marker of the current sequence
+ * causing the current position in the sequence to be pushed onto a stack
+ * to allow the current position to be overwritten by the position referenced
+ * in the special ematch. Matching continues in the new sequence until a
+ * marker is reached causing the position to be restored from the stack.
+ *
+ * Example:
+ *          A AND (B1 OR B2) AND C AND D
+ *
+ *              ------->-PUSH-------
+ *    -->--    /         -->--      \   -->--
+ *   /     \  /         /     \      \ /     \
+ * +-------+-------+-------+-------+-------+--------+
+ * | A AND | B AND | C AND | D END | B1 OR | B2 END |
+ * +-------+-------+-------+-------+-------+--------+
+ *                    \                      /
+ *                     --------<-POP---------
+ *
+ * where B is a virtual ematch referencing to sequence starting with B1.
+ * 
+ * ==========================================================================
+ *
+ * How to write an ematch in 60 seconds
+ * ------------------------------------
+ * 
+ *   1) Provide a matcher function:
+ *      static int my_match(struct sk_buff *skb, struct tcf_ematch *m,
+ *                          struct tcf_pkt_info *info)
+ *      {
+ *      	struct mydata *d = (struct mydata *) m->data;
+ *
+ *      	if (...matching goes here...)
+ *      		return 1;
+ *      	else
+ *      		return 0;
+ *      }
+ *
+ *   2) Fill out a struct tcf_ematch_ops:
+ *      static struct tcf_ematch_ops my_ops = {
+ *      	.kind = unique id,
+ *      	.datalen = sizeof(struct mydata),
+ *      	.match = my_match,
+ *      	.owner = THIS_MODULE,
+ *      };
+ *
+ *   3) Register/Unregister your ematch:
+ *      static int __init init_my_ematch(void)
+ *      {
+ *      	return tcf_em_register(&my_ops);
+ *      }
+ *
+ *      static void __exit exit_my_ematch(void)
+ *      {
+ *      	return tcf_em_unregister(&my_ops);
+ *      }
+ *
+ *      module_init(init_my_ematch);
+ *      module_exit(exit_my_ematch);
+ *
+ *   4) By now you should have two more seconds left, barely enough to
+ *      open up a beer to watch the compilation going.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/rtnetlink.h>
+#include <linux/skbuff.h>
+#include <net/pkt_cls.h>
+#include <config/net/ematch/stack.h>
+
+static LIST_HEAD(ematch_ops);
+static DEFINE_RWLOCK(ematch_mod_lock);
+
+static inline struct tcf_ematch_ops * tcf_em_lookup(u16 kind)
+{
+	struct tcf_ematch_ops *e = NULL;
+
+	read_lock(&ematch_mod_lock);
+	list_for_each_entry(e, &ematch_ops, link) {
+		if (kind == e->kind) {
+			if (!try_module_get(e->owner))
+				e = NULL;
+			read_unlock(&ematch_mod_lock);
+			return e;
+		}
+	}
+	read_unlock(&ematch_mod_lock);
+
+	return NULL;
+}
+
+/**
+ * tcf_em_register - register an extended match
+ * 
+ * @ops: ematch operations lookup table
+ *
+ * This function must be called by ematches to announce their presence.
+ * The given @ops must have kind set to a unique identifier and the
+ * callback match() must be implemented. All other callbacks are optional
+ * and a fallback implementation is used instead.
+ *
+ * Returns -EEXISTS if an ematch of the same kind has already registered.
+ */
+int tcf_em_register(struct tcf_ematch_ops *ops)
+{
+	int err = -EEXIST;
+	struct tcf_ematch_ops *e;
+
+	if (ops->match == NULL)
+		return -EINVAL;
+
+	write_lock(&ematch_mod_lock);
+	list_for_each_entry(e, &ematch_ops, link)
+		if (ops->kind == e->kind)
+			goto errout;
+
+	list_add_tail(&ops->link, &ematch_ops);
+	err = 0;
+errout:
+	write_unlock(&ematch_mod_lock);
+	return err;
+}
+
+/**
+ * tcf_em_unregister - unregster and extended match
+ *
+ * @ops: ematch operations lookup table
+ *
+ * This function must be called by ematches to announce their disappearance
+ * for examples when the module gets unloaded. The @ops parameter must be
+ * the same as the one used for registration.
+ *
+ * Returns -ENOENT if no matching ematch was found.
+ */
+int tcf_em_unregister(struct tcf_ematch_ops *ops)
+{
+	int err = 0;
+	struct tcf_ematch_ops *e;
+
+	write_lock(&ematch_mod_lock);
+	list_for_each_entry(e, &ematch_ops, link) {
+		if (e == ops) {
+			list_del(&e->link);
+			goto out;
+		}
+	}
+
+	err = -ENOENT;
+out:
+	write_unlock(&ematch_mod_lock);
+	return err;
+}
+
+static inline struct tcf_ematch * tcf_em_get_match(struct tcf_ematch_tree *tree,
+						   int index)
+{
+	return &tree->matches[index];
+}
+
+
+static int tcf_em_validate(struct tcf_proto *tp,
+			   struct tcf_ematch_tree_hdr *tree_hdr,
+			   struct tcf_ematch *em, struct rtattr *rta, int idx)
+{
+	int err = -EINVAL;
+	struct tcf_ematch_hdr *em_hdr = RTA_DATA(rta);
+	int data_len = RTA_PAYLOAD(rta) - sizeof(*em_hdr);
+	void *data = (void *) em_hdr + sizeof(*em_hdr);
+
+	if (!TCF_EM_REL_VALID(em_hdr->flags))
+		goto errout;
+
+	if (em_hdr->kind == TCF_EM_CONTAINER) {
+		/* Special ematch called "container", carries an index
+		 * referencing an external ematch sequence. */
+		u32 ref;
+
+		if (data_len < sizeof(ref))
+			goto errout;
+		ref = *(u32 *) data;
+
+		if (ref >= tree_hdr->nmatches)
+			goto errout;
+
+		/* We do not allow backward jumps to avoid loops and jumps
+		 * to our own position are of course illegal. */
+		if (ref <= idx)
+			goto errout;
+
+		
+		em->data = ref;
+	} else {
+		/* Note: This lookup will increase the module refcnt
+		 * of the ematch module referenced. In case of a failure,
+		 * a destroy function is called by the underlying layer
+		 * which automatically releases the reference again, therefore
+		 * the module MUST not be given back under any circumstances
+		 * here. Be aware, the destroy function assumes that the
+		 * module is held if the ops field is non zero. */
+		em->ops = tcf_em_lookup(em_hdr->kind);
+
+		if (em->ops == NULL) {
+			err = -ENOENT;
+			goto errout;
+		}
+
+		/* ematch module provides expected length of data, so we
+		 * can do a basic sanity check. */
+		if (em->ops->datalen && data_len < em->ops->datalen)
+			goto errout;
+
+		if (em->ops->change) {
+			err = em->ops->change(tp, data, data_len, em);
+			if (err < 0)
+				goto errout;
+		} else if (data_len > 0) {
+			/* ematch module doesn't provide an own change
+			 * procedure and expects us to allocate and copy
+			 * the ematch data.
+			 *
+			 * TCF_EM_SIMPLE may be specified stating that the
+			 * data only consists of a u32 integer and the module
+			 * does not expected a memory reference but rather
+			 * the value carried. */
+			if (em_hdr->flags & TCF_EM_SIMPLE) {
+				if (data_len < sizeof(u32))
+					goto errout;
+				em->data = *(u32 *) data;
+			} else {
+				void *v = kmalloc(data_len, GFP_KERNEL);
+				if (v == NULL) {
+					err = -ENOBUFS;
+					goto errout;
+				}
+				memcpy(v, data, data_len);
+				em->data = (unsigned long) v;
+			}
+		}
+	}
+
+	em->matchid = em_hdr->matchid;
+	em->flags = em_hdr->flags;
+	em->datalen = data_len;
+
+	err = 0;
+errout:
+	return err;
+}
+
+/**
+ * tcf_em_tree_validate - validate ematch config TLV and build ematch tree
+ *
+ * @tp: classifier kind handle
+ * @rta: ematch tree configuration TLV
+ * @tree: destination ematch tree variable to store the resulting
+ *        ematch tree.
+ *
+ * This function validates the given configuration TLV @rta and builds an
+ * ematch tree in @tree. The resulting tree must later be copied into
+ * the private classifier data using tcf_em_tree_change(). You MUST NOT
+ * provide the ematch tree variable of the private classifier data directly,
+ * the changes would not be locked properly.
+ *
+ * Returns a negative error code if the configuration TLV contains errors.
+ */
+int tcf_em_tree_validate(struct tcf_proto *tp, struct rtattr *rta,
+			 struct tcf_ematch_tree *tree)
+{
+	int idx, list_len, matches_len, err = -EINVAL;
+	struct rtattr *tb[TCA_EMATCH_TREE_MAX];
+	struct rtattr *rt_match, *rt_hdr, *rt_list;
+	struct tcf_ematch_tree_hdr *tree_hdr;
+	struct tcf_ematch *em;
+
+	if (rtattr_parse_nested(tb, TCA_EMATCH_TREE_MAX, rta) < 0)
+		goto errout;
+
+	rt_hdr = tb[TCA_EMATCH_TREE_HDR-1];
+	rt_list = tb[TCA_EMATCH_TREE_LIST-1];
+
+	if (rt_hdr == NULL || rt_list == NULL)
+		goto errout;
+
+	if (RTA_PAYLOAD(rt_hdr) < sizeof(*tree_hdr) ||
+	    RTA_PAYLOAD(rt_list) < sizeof(*rt_match))
+		goto errout;
+
+	tree_hdr = RTA_DATA(rt_hdr);
+	memcpy(&tree->hdr, tree_hdr, sizeof(*tree_hdr));
+
+	rt_match = RTA_DATA(rt_list);
+	list_len = RTA_PAYLOAD(rt_list);
+	matches_len = tree_hdr->nmatches * sizeof(*em);
+
+	tree->matches = kmalloc(matches_len, GFP_KERNEL);
+	if (tree->matches == NULL)
+		goto errout;
+	memset(tree->matches, 0, matches_len);
+
+	/* We do not use rtattr_parse_nested here because the maximum
+	 * number of attributes is unknown. This saves us the allocation
+	 * for a tb buffer which would serve no purpose at all.
+	 * 
+	 * The array of rt attributes is parsed in the order as they are
+	 * provided, their type must be incremental from 1 to n. Even
+	 * if it does not serve any real purpose, a failure of sticking
+	 * to this policy will result in parsing failure. */
+	for (idx = 0; RTA_OK(rt_match, list_len); idx++) {
+		err = -EINVAL;
+
+		if (rt_match->rta_type != (idx + 1))
+			goto errout_abort;
+
+		if (idx >= tree_hdr->nmatches)
+			goto errout_abort;
+
+		if (RTA_PAYLOAD(rt_match) < sizeof(struct tcf_ematch_hdr))
+			goto errout_abort;
+
+		em = tcf_em_get_match(tree, idx);
+
+		err = tcf_em_validate(tp, tree_hdr, em, rt_match, idx);
+		if (err < 0)
+			goto errout_abort;
+
+		rt_match = RTA_NEXT(rt_match, list_len);
+	}
+
+	/* Check if the number of matches provided by userspace actually
+	 * complies with the array of matches. The number was used for
+	 * the validation of references and a mismatch could lead to
+	 * undefined references during the matching process. */
+	if (idx != tree_hdr->nmatches) {
+		err = -EINVAL;
+		goto errout_abort;
+	}
+
+	err = 0;
+errout:
+	return err;
+
+errout_abort:
+	tcf_em_tree_destroy(tp, tree);
+	return err;
+}
+
+/**
+ * tcf_em_tree_destroy - destroy an ematch tree
+ *
+ * @tp: classifier kind handle
+ * @tree: ematch tree to be deleted
+ *
+ * This functions destroys an ematch tree previously created by
+ * tcf_em_tree_validate()/tcf_em_tree_change(). You must ensure that
+ * the ematch tree is not in use before calling this function.
+ */
+void tcf_em_tree_destroy(struct tcf_proto *tp, struct tcf_ematch_tree *tree)
+{
+	int i;
+
+	if (tree->matches == NULL)
+		return;
+
+	for (i = 0; i < tree->hdr.nmatches; i++) {
+		struct tcf_ematch *em = tcf_em_get_match(tree, i);
+
+		if (em->ops) {
+			if (em->ops->destroy)
+				em->ops->destroy(tp, em);
+			else if (!tcf_em_is_simple(em) && em->data)
+				kfree((void *) em->data);
+			module_put(em->ops->owner);
+		}
+	}
+	
+	tree->hdr.nmatches = 0;
+	kfree(tree->matches);
+}
+
+/**
+ * tcf_em_tree_dump - dump ematch tree into a rtnl message
+ *
+ * @skb: skb holding the rtnl message
+ * @t: ematch tree to be dumped
+ * @tlv: TLV type to be used to encapsulate the tree
+ *
+ * This function dumps a ematch tree into a rtnl message. It is valid to
+ * call this function while the ematch tree is in use.
+ *
+ * Returns -1 if the skb tailroom is insufficient.
+ */
+int tcf_em_tree_dump(struct sk_buff *skb, struct tcf_ematch_tree *tree, int tlv)
+{
+	int i;
+	struct rtattr * top_start = (struct rtattr*) skb->tail;
+	struct rtattr * list_start;
+
+	RTA_PUT(skb, tlv, 0, NULL);
+	RTA_PUT(skb, TCA_EMATCH_TREE_HDR, sizeof(tree->hdr), &tree->hdr);
+
+	list_start = (struct rtattr *) skb->tail;
+	RTA_PUT(skb, TCA_EMATCH_TREE_LIST, 0, NULL);
+
+	for (i = 0; i < tree->hdr.nmatches; i++) {
+		struct rtattr *match_start = (struct rtattr*) skb->tail;
+		struct tcf_ematch *em = tcf_em_get_match(tree, i);
+		struct tcf_ematch_hdr em_hdr = {
+			.kind = em->ops ? em->ops->kind : TCF_EM_CONTAINER,
+			.matchid = em->matchid,
+			.flags = em->flags
+		};
+
+		RTA_PUT(skb, i+1, sizeof(em_hdr), &em_hdr);
+
+		if (em->ops && em->ops->dump) {
+			if (em->ops->dump(skb, em) < 0)
+				goto rtattr_failure;
+		} else if (tcf_em_is_container(em) || tcf_em_is_simple(em)) {
+			u32 u = em->data;
+			RTA_PUT_NOHDR(skb, sizeof(u), &u);
+		} else if (em->datalen > 0)
+			RTA_PUT_NOHDR(skb, em->datalen, (void *) em->data);
+
+		match_start->rta_len = skb->tail - (u8*) match_start;
+	}
+
+	list_start->rta_len = skb->tail - (u8 *) list_start;
+	top_start->rta_len = skb->tail - (u8 *) top_start;
+
+	return 0;
+
+rtattr_failure:
+	return -1;
+}
+
+static inline int tcf_em_match(struct sk_buff *skb, struct tcf_ematch *em,
+			       struct tcf_pkt_info *info)
+{
+	int r = em->ops->match(skb, em, info);
+	return tcf_em_is_inverted(em) ? !r : r;
+}
+
+/* Do not use this function directly, use tcf_em_tree_match instead */
+int __tcf_em_tree_match(struct sk_buff *skb, struct tcf_ematch_tree *tree,
+			struct tcf_pkt_info *info)
+{
+	int stackp = 0, match_idx = 0, res = 0;
+	struct tcf_ematch *cur_match;
+	int stack[CONFIG_NET_EMATCH_STACK];
+
+proceed:
+	while (match_idx < tree->hdr.nmatches) {
+		cur_match = tcf_em_get_match(tree, match_idx);
+
+		if (tcf_em_is_container(cur_match)) {
+			if (unlikely(stackp >= CONFIG_NET_EMATCH_STACK))
+				goto stack_overflow;
+
+			stack[stackp++] = match_idx;
+			match_idx = cur_match->data;
+			goto proceed;
+		}
+
+		res = tcf_em_match(skb, cur_match, info);
+
+		if (tcf_em_early_end(cur_match, res))
+			break;
+
+		match_idx++;
+	}
+
+pop_stack:
+	if (stackp > 0) {
+		match_idx = stack[--stackp];
+		cur_match = tcf_em_get_match(tree, match_idx);
+
+		if (tcf_em_early_end(cur_match, res))
+			goto pop_stack;
+		else {
+			match_idx++;
+			goto proceed;
+		}
+	}
+
+	return res;
+
+stack_overflow:
+	if (net_ratelimit())
+		printk("Local stack overflow, increase NET_EMATCH_STACK\n");
+	return -1;
+}
+
+EXPORT_SYMBOL(tcf_em_register);
+EXPORT_SYMBOL(tcf_em_unregister);
+EXPORT_SYMBOL(tcf_em_tree_validate);
+EXPORT_SYMBOL(tcf_em_tree_destroy);
+EXPORT_SYMBOL(tcf_em_tree_dump);
+EXPORT_SYMBOL(__tcf_em_tree_match);