[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>

4 files changed, 43 insertions, 369 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;
 }
diff --git a/net/netlabel/netlabel_domainhash.h b/net/netlabel/netlabel_domainhash.h
index 99a2287de246..02af72a7877c 100644
--- a/net/netlabel/netlabel_domainhash.h
+++ b/net/netlabel/netlabel_domainhash.h
@@ -61,7 +61,9 @@ int netlbl_domhsh_add(struct netlbl_dom_map *entry);
 int netlbl_domhsh_add_default(struct netlbl_dom_map *entry);
 int netlbl_domhsh_remove_default(void);
 struct netlbl_dom_map *netlbl_domhsh_getentry(const char *domain);
-struct sk_buff *netlbl_domhsh_dump(size_t headroom);
-struct sk_buff *netlbl_domhsh_dump_default(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);
 
 #endif
diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
index 73cbe66e42ff..eeb7d768d2bb 100644
--- a/net/netlabel/netlabel_user.c
+++ b/net/netlabel/netlabel_user.c
@@ -74,85 +74,3 @@ int netlbl_netlink_init(void)
 
         return 0;
 }
-
-/*
- * NetLabel Common Protocol Functions
- */
-
-/**
- * netlbl_netlink_send_ack - Send an ACK message
- * @info: the generic NETLINK information
- * @genl_family: the generic NETLINK family ID value
- * @ack_cmd: the generic NETLINK family ACK command value
- * @ret_code: return code to use
- *
- * Description:
- * This function sends an ACK message to the sender of the NETLINK message
- * specified by @info.
- *
- */
-void netlbl_netlink_send_ack(const struct genl_info *info,
-                             u32 genl_family,
-                             u8 ack_cmd,
-                             u32 ret_code)
-{
-        size_t data_size;
-        struct sk_buff *skb;
-
-        data_size = GENL_HDRLEN + 2 * NETLBL_LEN_U32;
-        skb = netlbl_netlink_alloc_skb(0, data_size, GFP_KERNEL);
-        if (skb == NULL)
-                return;
-
-        if (netlbl_netlink_hdr_put(skb,
-                                   info->snd_pid,
-                                   0,
-                                   genl_family,
-                                   ack_cmd) == NULL)
-                goto send_ack_failure;
-
-        if (nla_put_u32(skb, NLA_U32, info->snd_seq) != 0)
-                goto send_ack_failure;
-        if (nla_put_u32(skb, NLA_U32, ret_code) != 0)
-                goto send_ack_failure;
-
-        netlbl_netlink_snd(skb, info->snd_pid);
-        return;
-
-send_ack_failure:
-        kfree_skb(skb);
-}
-
-/*
- * NETLINK I/O Functions
- */
-
-/**
- * netlbl_netlink_snd - Send a NetLabel message
- * @skb: NetLabel message
- * @pid: destination PID
- *
- * Description:
- * Sends a unicast NetLabel message over the NETLINK socket.
- *
- */
-int netlbl_netlink_snd(struct sk_buff *skb, u32 pid)
-{
-        return genlmsg_unicast(skb, pid);
-}
-
-/**
- * netlbl_netlink_snd - Send a NetLabel message
- * @skb: NetLabel message
- * @pid: sending PID
- * @group: multicast group id
- *
- * Description:
- * Sends a multicast NetLabel message over the NETLINK socket to all members
- * of @group except @pid.
- *
- */
-int netlbl_netlink_snd_multicast(struct sk_buff *skb, u32 pid, u32 group)
-{
-        return genlmsg_multicast(skb, pid, group, GFP_KERNEL);
-}
diff --git a/net/netlabel/netlabel_user.h b/net/netlabel/netlabel_user.h
index 385a6c7488c6..3f9386b917df 100644
--- a/net/netlabel/netlabel_user.h
+++ b/net/netlabel/netlabel_user.h
@@ -41,72 +41,6 @@
 /* NetLabel NETLINK helper functions */
 
 /**
- * netlbl_netlink_cap_check - Check the NETLINK msg capabilities
- * @skb: the NETLINK buffer
- * @req_cap: the required capability
- *
- * Description:
- * Check the NETLINK buffer's capabilities against the required capabilities.
- * Returns zero on success, negative values on failure.
- *
- */
-static inline int netlbl_netlink_cap_check(const struct sk_buff *skb,
-                                           kernel_cap_t req_cap)
-{
-        if (cap_raised(NETLINK_CB(skb).eff_cap, req_cap))
-                return 0;
-        return -EPERM;
-}
-
-/**
- * netlbl_getinc_u8 - Read a u8 value from a nlattr stream and move on
- * @nla: the attribute
- * @rem_len: remaining length
- *
- * Description:
- * Return a u8 value pointed to by @nla and advance it to the next attribute.
- *
- */
-static inline u8 netlbl_getinc_u8(struct nlattr **nla, int *rem_len)
-{
-        u8 val = nla_get_u8(*nla);
-        *nla = nla_next(*nla, rem_len);
-        return val;
-}
-
-/**
- * netlbl_getinc_u16 - Read a u16 value from a nlattr stream and move on
- * @nla: the attribute
- * @rem_len: remaining length
- *
- * Description:
- * Return a u16 value pointed to by @nla and advance it to the next attribute.
- *
- */
-static inline u16 netlbl_getinc_u16(struct nlattr **nla, int *rem_len)
-{
-        u16 val = nla_get_u16(*nla);
-        *nla = nla_next(*nla, rem_len);
-        return val;
-}
-
-/**
- * netlbl_getinc_u32 - Read a u32 value from a nlattr stream and move on
- * @nla: the attribute
- * @rem_len: remaining length
- *
- * Description:
- * Return a u32 value pointed to by @nla and advance it to the next attribute.
- *
- */
-static inline u32 netlbl_getinc_u32(struct nlattr **nla, int *rem_len)
-{
-        u32 val = nla_get_u32(*nla);
-        *nla = nla_next(*nla, rem_len);
-        return val;
-}
-
-/**
  * netlbl_netlink_hdr_put - Write the NETLINK buffers into a sk_buff
  * @skb: the packet
  * @pid: the PID of the receipient
@@ -124,6 +58,7 @@ static inline void *netlbl_netlink_hdr_put(struct sk_buff *skb,
                                            u32 pid,
                                            u32 seq,
                                            int type,
+                                           int flags,
                                            u8 cmd)
 {
         return genlmsg_put(skb,
@@ -131,85 +66,13 @@ static inline void *netlbl_netlink_hdr_put(struct sk_buff *skb,
                            seq,
                            type,
                            0,
-                           0,
+                           flags,
                            cmd,
                            NETLBL_PROTO_VERSION);
 }
 
-/**
- * netlbl_netlink_hdr_push - Write the NETLINK buffers into a sk_buff
- * @skb: the packet
- * @pid: the PID of the receipient
- * @seq: the sequence number
- * @type: the generic NETLINK message family type
- * @cmd: command
- *
- * Description:
- * Write both a NETLINK nlmsghdr structure and a Generic NETLINK genlmsghdr
- * struct to the packet.
- *
- */
-static inline void netlbl_netlink_hdr_push(struct sk_buff *skb,
-                                           u32 pid,
-                                           u32 seq,
-                                           int type,
-                                           u8 cmd)
-
-{
-        struct nlmsghdr *nlh;
-        struct genlmsghdr *hdr;
-
-        nlh = (struct nlmsghdr *)skb_push(skb, NLMSG_SPACE(GENL_HDRLEN));
-        nlh->nlmsg_type = type;
-        nlh->nlmsg_len = skb->len;
-        nlh->nlmsg_flags = 0;
-        nlh->nlmsg_pid = pid;
-        nlh->nlmsg_seq = seq;
-
-        hdr = nlmsg_data(nlh);
-        hdr->cmd = cmd;
-        hdr->version = NETLBL_PROTO_VERSION;
-        hdr->reserved = 0;
-}
-
-/**
- * netlbl_netlink_payload_len - Return the length of the payload
- * @skb: the NETLINK buffer
- *
- * Description:
- * This function returns the length of the NetLabel payload.
- *
- */
-static inline u32 netlbl_netlink_payload_len(const struct sk_buff *skb)
-{
-        return nlmsg_len((struct nlmsghdr *)skb->data) - GENL_HDRLEN;
-}
-
-/**
- * netlbl_netlink_payload_data - Returns a pointer to the start of the payload
- * @skb: the NETLINK buffer
- *
- * Description:
- * This function returns a pointer to the start of the NetLabel payload.
- *
- */
-static inline void *netlbl_netlink_payload_data(const struct sk_buff *skb)
-{
-  return (unsigned char *)nlmsg_data((struct nlmsghdr *)skb->data) +
-          GENL_HDRLEN;
-}
-
-/* NetLabel common protocol functions */
-
-void netlbl_netlink_send_ack(const struct genl_info *info,
-                             u32 genl_family,
-                             u8 ack_cmd,
-                             u32 ret_code);
-
 /* NetLabel NETLINK I/O functions */
 
 int netlbl_netlink_init(void);
-int netlbl_netlink_snd(struct sk_buff *skb, u32 pid);
-int netlbl_netlink_snd_multicast(struct sk_buff *skb, u32 pid, u32 group);
 
 #endif