[NETLINK]: Introduce nested and byteorder flag to netlink attribute

This change allows the generic attribute interface to be used within
the netfilter subsystem where this flag was initially introduced.

The byte-order flag is yet unused, it's intended use is to
allow automatic byte order convertions for all atomic types.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

7 files changed, 38 insertions, 15 deletions

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index d2843ae4a83a..e638256ce472 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -131,6 +131,20 @@ struct nlattr
         __u16           nla_type;
 };
 
+/*
+ * nla_type (16 bits)
+ * +---+---+-------------------------------+
+ * | N | O | Attribute Type                |
+ * +---+---+-------------------------------+
+ * N := Carries nested attributes
+ * O := Payload stored in network byte order
+ *
+ * Note: The N and O flag are mutually exclusive.
+ */
+#define NLA_F_NESTED            (1 << 15)
+#define NLA_F_NET_BYTEORDER     (1 << 14)
+#define NLA_TYPE_MASK           ~(NLA_F_NESTED | NLA_F_NET_BYTEORDER)
+
 #define NLA_ALIGNTO             4
 #define NLA_ALIGN(len)          (((len) + NLA_ALIGNTO - 1) & ~(NLA_ALIGNTO - 1))
 #define NLA_HDRLEN              ((int) NLA_ALIGN(sizeof(struct nlattr)))
diff --git a/include/net/netlink.h b/include/net/netlink.h
index d7b824be5422..695e613a207b 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -667,6 +667,15 @@ static inline int nla_padlen(int payload)
 }
 
 /**
+ * nla_type - attribute type
+ * @nla: netlink attribute
+ */
+static inline int nla_type(const struct nlattr *nla)
+{
+        return nla->nla_type & NLA_TYPE_MASK;
+}
+
+/**
  * nla_data - head of payload
  * @nla: netlink attribute
  */
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index df17aab193b4..f823ca34cb12 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -487,7 +487,7 @@ static int rtm_to_fib_config(struct sk_buff *skb, struct nlmsghdr *nlh,
         }
 
         nlmsg_for_each_attr(attr, nlh, sizeof(struct rtmsg), remaining) {
-                switch (attr->nla_type) {
+                switch (nla_type(attr)) {
                 case RTA_DST:
                         cfg->fc_dst = nla_get_be32(attr);
                         break;
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index d30fb68d5f4e..1351a2617dce 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -743,7 +743,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
                 int remaining;
 
                 nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
-                        int type = nla->nla_type;
+                        int type = nla_type(nla);
 
                         if (type) {
                                 if (type > RTAX_MAX)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 5bdd9d4010fe..104070e92cea 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1279,7 +1279,7 @@ install_route:
                 int remaining;
 
                 nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
-                        int type = nla->nla_type;
+                        int type = nla_type(nla);
 
                         if (type) {
                                 if (type > RTAX_MAX) {
diff --git a/net/netlabel/netlabel_cipso_v4.c b/net/netlabel/netlabel_cipso_v4.c
index c060e3f991f1..ba0ca8d3f77d 100644
--- a/net/netlabel/netlabel_cipso_v4.c
+++ b/net/netlabel/netlabel_cipso_v4.c
@@ -130,7 +130,7 @@ static int netlbl_cipsov4_add_common(struct genl_info *info,
                 return -EINVAL;
 
         nla_for_each_nested(nla, info->attrs[NLBL_CIPSOV4_A_TAGLST], nla_rem)
-                if (nla->nla_type == NLBL_CIPSOV4_A_TAG) {
+                if (nla_type(nla) == NLBL_CIPSOV4_A_TAG) {
                         if (iter >= CIPSO_V4_TAG_MAXCNT)
                                 return -EINVAL;
                         doi_def->tags[iter++] = nla_get_u8(nla);
@@ -192,13 +192,13 @@ static int netlbl_cipsov4_add_std(struct genl_info *info)
         nla_for_each_nested(nla_a,
                             info->attrs[NLBL_CIPSOV4_A_MLSLVLLST],
                             nla_a_rem)
-                if (nla_a->nla_type == NLBL_CIPSOV4_A_MLSLVL) {
+                if (nla_type(nla_a) == NLBL_CIPSOV4_A_MLSLVL) {
                         if (nla_validate_nested(nla_a,
                                             NLBL_CIPSOV4_A_MAX,
                                             netlbl_cipsov4_genl_policy) != 0)
                                         goto add_std_failure;
                         nla_for_each_nested(nla_b, nla_a, nla_b_rem)
-                                switch (nla_b->nla_type) {
+                                switch (nla_type(nla_b)) {
                                 case NLBL_CIPSOV4_A_MLSLVLLOC:
                                         if (nla_get_u32(nla_b) >
                                             CIPSO_V4_MAX_LOC_LVLS)
@@ -240,7 +240,7 @@ static int netlbl_cipsov4_add_std(struct genl_info *info)
         nla_for_each_nested(nla_a,
                             info->attrs[NLBL_CIPSOV4_A_MLSLVLLST],
                             nla_a_rem)
-                if (nla_a->nla_type == NLBL_CIPSOV4_A_MLSLVL) {
+                if (nla_type(nla_a) == NLBL_CIPSOV4_A_MLSLVL) {
                         struct nlattr *lvl_loc;
                         struct nlattr *lvl_rem;
 
@@ -265,13 +265,13 @@ static int netlbl_cipsov4_add_std(struct genl_info *info)
                 nla_for_each_nested(nla_a,
                                     info->attrs[NLBL_CIPSOV4_A_MLSCATLST],
                                     nla_a_rem)
-                        if (nla_a->nla_type == NLBL_CIPSOV4_A_MLSCAT) {
+                        if (nla_type(nla_a) == NLBL_CIPSOV4_A_MLSCAT) {
                                 if (nla_validate_nested(nla_a,
                                               NLBL_CIPSOV4_A_MAX,
                                               netlbl_cipsov4_genl_policy) != 0)
                                         goto add_std_failure;
                                 nla_for_each_nested(nla_b, nla_a, nla_b_rem)
-                                        switch (nla_b->nla_type) {
+                                        switch (nla_type(nla_b)) {
                                         case NLBL_CIPSOV4_A_MLSCATLOC:
                                                 if (nla_get_u32(nla_b) >
                                                     CIPSO_V4_MAX_LOC_CATS)
@@ -315,7 +315,7 @@ static int netlbl_cipsov4_add_std(struct genl_info *info)
                 nla_for_each_nested(nla_a,
                                     info->attrs[NLBL_CIPSOV4_A_MLSCATLST],
                                     nla_a_rem)
-                        if (nla_a->nla_type == NLBL_CIPSOV4_A_MLSCAT) {
+                        if (nla_type(nla_a) == NLBL_CIPSOV4_A_MLSCAT) {
                                 struct nlattr *cat_loc;
                                 struct nlattr *cat_rem;
 
diff --git a/net/netlink/attr.c b/net/netlink/attr.c
index e4d7bed99c2e..ec39d12c2423 100644
--- a/net/netlink/attr.c
+++ b/net/netlink/attr.c
@@ -27,12 +27,12 @@ static int validate_nla(struct nlattr *nla, int maxtype,
                         const struct nla_policy *policy)
 {
         const struct nla_policy *pt;
-        int minlen = 0, attrlen = nla_len(nla);
+        int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
 
-        if (nla->nla_type <= 0 || nla->nla_type > maxtype)
+        if (type <= 0 || type > maxtype)
                 return 0;
 
-        pt = &policy[nla->nla_type];
+        pt = &policy[type];
 
         BUG_ON(pt->type > NLA_TYPE_MAX);
 
@@ -149,7 +149,7 @@ int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
         memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
 
         nla_for_each_attr(nla, head, len, rem) {
-                u16 type = nla->nla_type;
+                u16 type = nla_type(nla);
 
                 if (type > 0 && type <= maxtype) {
                         if (policy) {
@@ -185,7 +185,7 @@ struct nlattr *nla_find(struct nlattr *head, int len, int attrtype)
         int rem;
 
         nla_for_each_attr(nla, head, len, rem)
-                if (nla->nla_type == attrtype)
+                if (nla_type(nla) == attrtype)
                         return nla;
 
         return NULL;