[NetLabel]: rework the Netlink attribute handling (part 1)

At the suggestion of Thomas Graf, rewrite NetLabel's use of Netlink attributes
to better follow the common Netlink attribute usage.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 24 insertions, 179 deletions

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 87e7156..e6ce0b3 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -530,197 +530,42 @@ struct cipso_v4_doi *cipso_v4_doi_getdef(u32 doi)
 }
 
 /**
- * cipso_v4_doi_dump_all - Dump all the CIPSO DOI definitions into a sk_buff
- * @headroom: the amount of headroom to allocate for the sk_buff
+ * cipso_v4_doi_walk - Iterate through the DOI definitions
+ * @skip_cnt: skip past this number of DOI definitions, updated
+ * @callback: callback for each DOI definition
+ * @cb_arg: argument for the callback function
  *
  * Description:
- * Dump a list of all the configured DOI values into a sk_buff.  The returned
- * sk_buff has room at the front of the sk_buff for @headroom bytes.  See
- * net/netlabel/netlabel_cipso_v4.h for the LISTALL message format.  This
- * function may fail if another process is changing the DOI list at the same
- * time.  Returns a pointer to a sk_buff on success, NULL on error.
+ * Iterate over the DOI definition list, skipping the first @skip_cnt entries.
+ * For each entry call @callback, if @callback returns a negative value stop
+ * 'walking' through the list and return.  Updates the value in @skip_cnt upon
+ * return.  Returns zero on success, negative values on failure.
  *
  */
-struct sk_buff *cipso_v4_doi_dump_all(size_t headroom)
+int cipso_v4_doi_walk(u32 *skip_cnt,
+		     int (*callback) (struct cipso_v4_doi *doi_def, void *arg),
+		     void *cb_arg)
 {
-	struct sk_buff *skb = NULL;
-	struct cipso_v4_doi *iter;
+	int ret_val = -ENOENT;
 	u32 doi_cnt = 0;
-	ssize_t buf_len;
-
-	buf_len = NETLBL_LEN_U32;
-	rcu_read_lock();
-	list_for_each_entry_rcu(iter, &cipso_v4_doi_list, list)
-		if (iter->valid) {
-			doi_cnt += 1;
-			buf_len += 2 * NETLBL_LEN_U32;
-		}
-
-	skb = netlbl_netlink_alloc_skb(headroom, buf_len, GFP_ATOMIC);
-	if (skb == NULL)
-		goto doi_dump_all_failure;
-
-	if (nla_put_u32(skb, NLA_U32, doi_cnt) != 0)
-		goto doi_dump_all_failure;
-	buf_len -= NETLBL_LEN_U32;
-	list_for_each_entry_rcu(iter, &cipso_v4_doi_list, list)
-		if (iter->valid) {
-			if (buf_len < 2 * NETLBL_LEN_U32)
-				goto doi_dump_all_failure;
-			if (nla_put_u32(skb, NLA_U32, iter->doi) != 0)
-				goto doi_dump_all_failure;
-			if (nla_put_u32(skb, NLA_U32, iter->type) != 0)
-				goto doi_dump_all_failure;
-			buf_len -= 2 * NETLBL_LEN_U32;
-		}
-	rcu_read_unlock();
-
-	return skb;
-
-doi_dump_all_failure:
-	rcu_read_unlock();
-	kfree(skb);
-	return NULL;
-}
-
-/**
- * cipso_v4_doi_dump - Dump a CIPSO DOI definition into a sk_buff
- * @doi: the DOI value
- * @headroom: the amount of headroom to allocate for the sk_buff
- *
- * Description:
- * Lookup the DOI definition matching @doi and dump it's contents into a
- * sk_buff.  The returned sk_buff has room at the front of the sk_buff for
- * @headroom bytes.  See net/netlabel/netlabel_cipso_v4.h for the LIST message
- * format.  This function may fail if another process is changing the DOI list
- * at the same time.  Returns a pointer to a sk_buff on success, NULL on error.
- *
- */
-struct sk_buff *cipso_v4_doi_dump(u32 doi, size_t headroom)
-{
-	struct sk_buff *skb = NULL;
-	struct cipso_v4_doi *iter;
-	u32 tag_cnt = 0;
-	u32 lvl_cnt = 0;
-	u32 cat_cnt = 0;
-	ssize_t buf_len;
-	ssize_t tmp;
+	struct cipso_v4_doi *iter_doi;
 
 	rcu_read_lock();
-	iter = cipso_v4_doi_getdef(doi);
-	if (iter == NULL)
-		goto doi_dump_failure;
-	buf_len = NETLBL_LEN_U32;
-	switch (iter->type) {
-	case CIPSO_V4_MAP_PASS:
-		buf_len += NETLBL_LEN_U32;
-		while(tag_cnt < CIPSO_V4_TAG_MAXCNT &&
-		      iter->tags[tag_cnt] != CIPSO_V4_TAG_INVALID) {
-			tag_cnt += 1;
-			buf_len += NETLBL_LEN_U8;
-		}
-		break;
-	case CIPSO_V4_MAP_STD:
-		buf_len += 3 * NETLBL_LEN_U32;
-		while (tag_cnt < CIPSO_V4_TAG_MAXCNT &&
-		       iter->tags[tag_cnt] != CIPSO_V4_TAG_INVALID) {
-			tag_cnt += 1;
-			buf_len += NETLBL_LEN_U8;
-		}
-		for (tmp = 0; tmp < iter->map.std->lvl.local_size; tmp++)
-			if (iter->map.std->lvl.local[tmp] !=
-			    CIPSO_V4_INV_LVL) {
-				lvl_cnt += 1;
-				buf_len += NETLBL_LEN_U32 + NETLBL_LEN_U8;
+	list_for_each_entry_rcu(iter_doi, &cipso_v4_doi_list, list)
+		if (iter_doi->valid) {
+			if (doi_cnt++ < *skip_cnt)
+				continue;
+			ret_val = callback(iter_doi, cb_arg);
+			if (ret_val < 0) {
+				doi_cnt--;
+				goto doi_walk_return;
 			}
-		for (tmp = 0; tmp < iter->map.std->cat.local_size; tmp++)
-			if (iter->map.std->cat.local[tmp] !=
-			    CIPSO_V4_INV_CAT) {
-				cat_cnt += 1;
-				buf_len += NETLBL_LEN_U32 + NETLBL_LEN_U16;
-			}
-		break;
-	}
-
-	skb = netlbl_netlink_alloc_skb(headroom, buf_len, GFP_ATOMIC);
-	if (skb == NULL)
-		goto doi_dump_failure;
-
-	if (nla_put_u32(skb, NLA_U32, iter->type) != 0)
-		goto doi_dump_failure;
-	buf_len -= NETLBL_LEN_U32;
-	if (iter != cipso_v4_doi_getdef(doi))
-		goto doi_dump_failure;
-	switch (iter->type) {
-	case CIPSO_V4_MAP_PASS:
-		if (nla_put_u32(skb, NLA_U32, tag_cnt) != 0)
-			goto doi_dump_failure;
-		buf_len -= NETLBL_LEN_U32;
-		for (tmp = 0;
-		     tmp < CIPSO_V4_TAG_MAXCNT &&
-			     iter->tags[tmp] != CIPSO_V4_TAG_INVALID;
-		     tmp++) {
-			if (buf_len < NETLBL_LEN_U8)
-				goto doi_dump_failure;
-			if (nla_put_u8(skb, NLA_U8, iter->tags[tmp]) != 0)
-				goto doi_dump_failure;
-			buf_len -= NETLBL_LEN_U8;
 		}
-		break;
-	case CIPSO_V4_MAP_STD:
-		if (nla_put_u32(skb, NLA_U32, tag_cnt) != 0)
-			goto doi_dump_failure;
-		if (nla_put_u32(skb, NLA_U32, lvl_cnt) != 0)
-			goto doi_dump_failure;
-		if (nla_put_u32(skb, NLA_U32, cat_cnt) != 0)
-			goto doi_dump_failure;
-		buf_len -= 3 * NETLBL_LEN_U32;
-		for (tmp = 0;
-		     tmp < CIPSO_V4_TAG_MAXCNT &&
-			     iter->tags[tmp] != CIPSO_V4_TAG_INVALID;
-		     tmp++) {
-			if (buf_len < NETLBL_LEN_U8)
-				goto doi_dump_failure;
-			if (nla_put_u8(skb, NLA_U8, iter->tags[tmp]) != 0)
-				goto doi_dump_failure;
-			buf_len -= NETLBL_LEN_U8;
-		}
-		for (tmp = 0; tmp < iter->map.std->lvl.local_size; tmp++)
-			if (iter->map.std->lvl.local[tmp] !=
-			    CIPSO_V4_INV_LVL) {
-				if (buf_len < NETLBL_LEN_U32 + NETLBL_LEN_U8)
-					goto doi_dump_failure;
-				if (nla_put_u32(skb, NLA_U32, tmp) != 0)
-					goto doi_dump_failure;
-				if (nla_put_u8(skb,
-					   NLA_U8,
-					   iter->map.std->lvl.local[tmp]) != 0)
-					goto doi_dump_failure;
-				buf_len -= NETLBL_LEN_U32 + NETLBL_LEN_U8;
-			}
-		for (tmp = 0; tmp < iter->map.std->cat.local_size; tmp++)
-			if (iter->map.std->cat.local[tmp] !=
-			    CIPSO_V4_INV_CAT) {
-				if (buf_len < NETLBL_LEN_U32 + NETLBL_LEN_U16)
-					goto doi_dump_failure;
-				if (nla_put_u32(skb, NLA_U32, tmp) != 0)
-					goto doi_dump_failure;
-				if (nla_put_u16(skb,
-					   NLA_U16,
-					   iter->map.std->cat.local[tmp]) != 0)
-					goto doi_dump_failure;
-				buf_len -= NETLBL_LEN_U32 + NETLBL_LEN_U16;
-			}
-		break;
-	}
-	rcu_read_unlock();
-
-	return skb;
 
-doi_dump_failure:
+doi_walk_return:
 	rcu_read_unlock();
-	kfree(skb);
-	return NULL;
+	*skip_cnt = doi_cnt;
+	return ret_val;
 }
 
 /**