[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, 37 insertions, 146 deletions

diff --git a/net/netlabel/netlabel_domainhash.c b/net/netlabel/netlabel_domainhash.c
index 0489a1378101..f56d7a8ac7b7 100644
--- a/net/netlabel/netlabel_domainhash.c
+++ b/net/netlabel/netlabel_domainhash.c
@@ -354,160 +354,51 @@ struct netlbl_dom_map *netlbl_domhsh_getentry(const char *domain)
 }
 
 /**
- * netlbl_domhsh_dump - Dump the domain hash table into a sk_buff
+ * netlbl_domhsh_walk - Iterate through the domain mapping hash table
+ * @skip_bkt: the number of buckets to skip at the start
+ * @skip_chain: the number of entries to skip in the first iterated bucket
+ * @callback: callback for each entry
+ * @cb_arg: argument for the callback function
  *
  * Description:
- * Dump the domain hash table into a buffer suitable for returning to an
- * application in response to a NetLabel management DOMAIN message.  This
- * function may fail if another process is growing the hash table at the same
- * time.  The returned sk_buff has room at the front of the sk_buff for
- * @headroom bytes.  See netlabel.h for the DOMAIN message format.  Returns a
- * pointer to a sk_buff on success, NULL on error.
+ * Interate over the domain mapping hash table, skipping the first @skip_bkt
+ * buckets and @skip_chain entries.  For each entry in the table call
+ * @callback, if @callback returns a negative value stop 'walking' through the
+ * table and return.  Updates the values in @skip_bkt and @skip_chain on
+ * return.  Returns zero on succcess, negative values on failure.
  *
  */
-struct sk_buff *netlbl_domhsh_dump(size_t headroom)
+int netlbl_domhsh_walk(u32 *skip_bkt,
+                     u32 *skip_chain,
+                     int (*callback) (struct netlbl_dom_map *entry, void *arg),
+                     void *cb_arg)
 {
-        struct sk_buff *skb = NULL;
-        ssize_t buf_len;
-        u32 bkt_iter;
-        u32 dom_cnt = 0;
-        struct netlbl_domhsh_tbl *hsh_tbl;
-        struct netlbl_dom_map *list_iter;
-        ssize_t tmp_len;
+        int ret_val = -ENOENT;
+        u32 iter_bkt;
+        struct netlbl_dom_map *iter_entry;
+        u32 chain_cnt = 0;
 
-        buf_len = NETLBL_LEN_U32;
         rcu_read_lock();
-        hsh_tbl = rcu_dereference(netlbl_domhsh);
-        for (bkt_iter = 0; bkt_iter < hsh_tbl->size; bkt_iter++)
-                list_for_each_entry_rcu(list_iter,
-                                        &hsh_tbl->tbl[bkt_iter], list) {
-                        buf_len += NETLBL_LEN_U32 +
-                                nla_total_size(strlen(list_iter->domain) + 1);
-                        switch (list_iter->type) {
-                        case NETLBL_NLTYPE_UNLABELED:
-                                break;
-                        case NETLBL_NLTYPE_CIPSOV4:
-                                buf_len += 2 * NETLBL_LEN_U32;
-                                break;
-                        }
-                        dom_cnt++;
-                }
-
-        skb = netlbl_netlink_alloc_skb(headroom, buf_len, GFP_ATOMIC);
-        if (skb == NULL)
-                goto dump_failure;
-
-        if (nla_put_u32(skb, NLA_U32, dom_cnt) != 0)
-                goto dump_failure;
-        buf_len -= NETLBL_LEN_U32;
-        hsh_tbl = rcu_dereference(netlbl_domhsh);
-        for (bkt_iter = 0; bkt_iter < hsh_tbl->size; bkt_iter++)
-                list_for_each_entry_rcu(list_iter,
-                                        &hsh_tbl->tbl[bkt_iter], list) {
-                        tmp_len = nla_total_size(strlen(list_iter->domain) +
-                                                 1);
-                        if (buf_len < NETLBL_LEN_U32 + tmp_len)
-                                goto dump_failure;
-                        if (nla_put_string(skb,
-                                           NLA_STRING,
-                                           list_iter->domain) != 0)
-                                goto dump_failure;
-                        if (nla_put_u32(skb, NLA_U32, list_iter->type) != 0)
-                                goto dump_failure;
-                        buf_len -= NETLBL_LEN_U32 + tmp_len;
-                        switch (list_iter->type) {
-                        case NETLBL_NLTYPE_UNLABELED:
-                                break;
-                        case NETLBL_NLTYPE_CIPSOV4:
-                                if (buf_len < 2 * NETLBL_LEN_U32)
-                                        goto dump_failure;
-                                if (nla_put_u32(skb,
-                                       NLA_U32,
-                                       list_iter->type_def.cipsov4->type) != 0)
-                                        goto dump_failure;
-                                if (nla_put_u32(skb,
-                                       NLA_U32,
-                                       list_iter->type_def.cipsov4->doi) != 0)
-                                        goto dump_failure;
-                                buf_len -= 2 * NETLBL_LEN_U32;
-                                break;
+        for (iter_bkt = *skip_bkt;
+             iter_bkt < rcu_dereference(netlbl_domhsh)->size;
+             iter_bkt++, chain_cnt = 0) {
+                list_for_each_entry_rcu(iter_entry,
+                                        &netlbl_domhsh->tbl[iter_bkt],
+                                        list)
+                        if (iter_entry->valid) {
+                                if (chain_cnt++ < *skip_chain)
+                                        continue;
+                                ret_val = callback(iter_entry, cb_arg);
+                                if (ret_val < 0) {
+                                        chain_cnt--;
+                                        goto walk_return;
+                                }
                         }
-                }
-        rcu_read_unlock();
-
-        return skb;
-
-dump_failure:
-        rcu_read_unlock();
-        kfree_skb(skb);
-        return NULL;
-}
-
-/**
- * netlbl_domhsh_dump_default - Dump the default domain mapping into a sk_buff
- *
- * Description:
- * Dump the default domain mapping into a buffer suitable for returning to an
- * application in response to a NetLabel management DEFDOMAIN message.  This
- * function may fail if another process is changing the default domain mapping
- * at the same time.  The returned sk_buff has room at the front of the
- * skb_buff for @headroom bytes.  See netlabel.h for the DEFDOMAIN message
- * format.  Returns a pointer to a sk_buff on success, NULL on error.
- *
- */
-struct sk_buff *netlbl_domhsh_dump_default(size_t headroom)
-{
-        struct sk_buff *skb;
-        ssize_t buf_len;
-        struct netlbl_dom_map *entry;
-
-        buf_len = NETLBL_LEN_U32;
-        rcu_read_lock();
-        entry = rcu_dereference(netlbl_domhsh_def);
-        if (entry != NULL)
-                switch (entry->type) {
-                case NETLBL_NLTYPE_UNLABELED:
-                        break;
-                case NETLBL_NLTYPE_CIPSOV4:
-                        buf_len += 2 * NETLBL_LEN_U32;
-                        break;
-                }
-
-        skb = netlbl_netlink_alloc_skb(headroom, buf_len, GFP_ATOMIC);
-        if (skb == NULL)
-                goto dump_default_failure;
-
-        if (entry != rcu_dereference(netlbl_domhsh_def))
-                goto dump_default_failure;
-        if (entry != NULL) {
-                if (nla_put_u32(skb, NLA_U32, entry->type) != 0)
-                        goto dump_default_failure;
-                buf_len -= NETLBL_LEN_U32;
-                switch (entry->type) {
-                case NETLBL_NLTYPE_UNLABELED:
-                        break;
-                case NETLBL_NLTYPE_CIPSOV4:
-                        if (buf_len < 2 * NETLBL_LEN_U32)
-                                goto dump_default_failure;
-                        if (nla_put_u32(skb,
-                                        NLA_U32,
-                                        entry->type_def.cipsov4->type) != 0)
-                                goto dump_default_failure;
-                        if (nla_put_u32(skb,
-                                        NLA_U32,
-                                        entry->type_def.cipsov4->doi) != 0)
-                                goto dump_default_failure;
-                        buf_len -= 2 * NETLBL_LEN_U32;
-                        break;
-                }
-        } else
-                nla_put_u32(skb, NLA_U32, NETLBL_NLTYPE_NONE);
-        rcu_read_unlock();
-
-        return skb;
+        }
 
-dump_default_failure:
+walk_return:
         rcu_read_unlock();
-        kfree_skb(skb);
-        return NULL;
+        *skip_bkt = iter_bkt;
+        *skip_chain = chain_cnt;
+        return ret_val;
 }