genetlink: add small version of ops

We want to add maxattr and policy back to genl_ops, to enable
dumping per command policy to user space. This, however, would
cause bloat for all the families with global policies. Introduce
smaller version of ops (half the size of genl_ops). Translate
these smaller ops into a full blown struct before use in the
core.

v1:
 - use struct assignment
 - put a full copy of the op in struct genl_dumpit_info
 - s/light/small/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/thermal/thermal_netlink.c b/drivers/thermal/thermal_netlink.c
index af7b2383e8f6b1fc2e3863ec419bdb77ff307e10..e9999d5dfdd52d31c5d407080e76b3d5875ae3d4 100644 (file)
--- a/drivers/thermal/thermal_netlink.c
+++ b/drivers/thermal/thermal_netlink.c
@@ -545,7 +545,7 @@ static int thermal_genl_cmd_dumpit(struct sk_buff *skb,
 {
        struct param p = { .msg = skb };
        const struct genl_dumpit_info *info = genl_dumpit_info(cb);
-       int cmd = info->ops->cmd;
+       int cmd = info->op.cmd;
        int ret;
        void *hdr;
 

diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index 5cd9ab0c6bd9507faf832b0f5b5932e222c089c3..8ea1fc1ed1c784e455dc8dfdccd4eeb75ae17080 100644 (file)
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h
@@ -41,6 +41,8 @@ struct genl_info;
  *     (private)
  * @ops: the operations supported by this family
  * @n_ops: number of operations supported by this family
+ * @small_ops: the small-struct operations supported by this family
+ * @n_small_ops: number of small-struct operations supported by this family
  */
 struct genl_family {
        int                     id;             /* private */
@@ -52,6 +54,7 @@ struct genl_family {
        u8                      netnsok:1;
        u8                      parallel_ops:1;
        u8                      n_ops;
+       u8                      n_small_ops;
        u8                      n_mcgrps;
        const struct nla_policy *policy;
        int                     (*pre_doit)(const struct genl_ops *ops,
@@ -61,6 +64,7 @@ struct genl_family {
                                             struct sk_buff *skb,
                                             struct genl_info *info);
        const struct genl_ops * ops;
+       const struct genl_small_ops *small_ops;
        const struct genl_multicast_group *mcgrps;
        struct module           *module;
 };
@@ -108,23 +112,26 @@ enum genl_validate_flags {
 };
 
 /**
- * struct genl_info - info that is available during dumpit op call
- * @family: generic netlink family - for internal genl code usage
- * @ops: generic netlink ops - for internal genl code usage
- * @attrs: netlink attributes
+ * struct genl_small_ops - generic netlink operations (small version)
+ * @cmd: command identifier
+ * @internal_flags: flags used by the family
+ * @flags: flags
+ * @validate: validation flags from enum genl_validate_flags
+ * @doit: standard command callback
+ * @dumpit: callback for dumpers
+ *
+ * This is a cut-down version of struct genl_ops for users who don't need
+ * most of the ancillary infra and want to save space.
  */
-struct genl_dumpit_info {
-       const struct genl_family *family;
-       const struct genl_ops *ops;
-       struct nlattr **attrs;
+struct genl_small_ops {
+       int     (*doit)(struct sk_buff *skb, struct genl_info *info);
+       int     (*dumpit)(struct sk_buff *skb, struct netlink_callback *cb);
+       u8      cmd;
+       u8      internal_flags;
+       u8      flags;
+       u8      validate;
 };
 
-static inline const struct genl_dumpit_info *
-genl_dumpit_info(struct netlink_callback *cb)
-{
-       return cb->data;
-}
-
 /**
  * struct genl_ops - generic netlink operations
  * @cmd: command identifier
@@ -148,6 +155,24 @@ struct genl_ops {
        u8                      validate;
 };
 
+/**
+ * struct genl_info - info that is available during dumpit op call
+ * @family: generic netlink family - for internal genl code usage
+ * @ops: generic netlink ops - for internal genl code usage
+ * @attrs: netlink attributes
+ */
+struct genl_dumpit_info {
+       const struct genl_family *family;
+       struct genl_ops op;
+       struct nlattr **attrs;
+};
+
+static inline const struct genl_dumpit_info *
+genl_dumpit_info(struct netlink_callback *cb)
+{
+       return cb->data;
+}
+
 int genl_register_family(struct genl_family *family);
 int genl_unregister_family(const struct genl_family *family);
 void genl_notify(const struct genl_family *family, struct sk_buff *skb,

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 4a95e85cf907289b96d67551c0fcdf40c598fa96..42a3c6c7a5ee240dae711a2ffad4b74999f8ede8 100644 (file)
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -107,16 +107,75 @@ static const struct genl_family *genl_family_find_byname(char *name)
        return NULL;
 }
 
-static const struct genl_ops *genl_get_cmd(u8 cmd,
-                                          const struct genl_family *family)
+static int genl_get_cmd_cnt(const struct genl_family *family)
+{
+       return family->n_ops + family->n_small_ops;
+}
+
+static void genl_op_from_full(const struct genl_family *family,
+                             unsigned int i, struct genl_ops *op)
+{
+       *op = family->ops[i];
+}
+
+static int genl_get_cmd_full(u8 cmd, const struct genl_family *family,
+                            struct genl_ops *op)
 {
        int i;
 
        for (i = 0; i < family->n_ops; i++)
-               if (family->ops[i].cmd == cmd)
-                       return &family->ops[i];
+               if (family->ops[i].cmd == cmd) {
+                       genl_op_from_full(family, i, op);
+                       return 0;
+               }
 
-       return NULL;
+       return -ENOENT;
+}
+
+static void genl_op_from_small(const struct genl_family *family,
+                              unsigned int i, struct genl_ops *op)
+{
+       memset(op, 0, sizeof(*op));
+       op->doit        = family->small_ops[i].doit;
+       op->dumpit      = family->small_ops[i].dumpit;
+       op->cmd         = family->small_ops[i].cmd;
+       op->internal_flags = family->small_ops[i].internal_flags;
+       op->flags       = family->small_ops[i].flags;
+       op->validate    = family->small_ops[i].validate;
+}
+
+static int genl_get_cmd_small(u8 cmd, const struct genl_family *family,
+                             struct genl_ops *op)
+{
+       int i;
+
+       for (i = 0; i < family->n_small_ops; i++)
+               if (family->small_ops[i].cmd == cmd) {
+                       genl_op_from_small(family, i, op);
+                       return 0;
+               }
+
+       return -ENOENT;
+}
+
+static int genl_get_cmd(u8 cmd, const struct genl_family *family,
+                       struct genl_ops *op)
+{
+       if (!genl_get_cmd_full(cmd, family, op))
+               return 0;
+       return genl_get_cmd_small(cmd, family, op);
+}
+
+static void genl_get_cmd_by_index(unsigned int i,
+                                 const struct genl_family *family,
+                                 struct genl_ops *op)
+{
+       if (i < family->n_ops)
+               genl_op_from_full(family, i, op);
+       else if (i < family->n_ops + family->n_small_ops)
+               genl_op_from_small(family, i - family->n_ops, op);
+       else
+               WARN_ON_ONCE(1);
 }
 
 static int genl_allocate_reserve_groups(int n_groups, int *first_id)
@@ -286,22 +345,25 @@ static void genl_unregister_mc_groups(const struct genl_family *family)
 
 static int genl_validate_ops(const struct genl_family *family)
 {
-       const struct genl_ops *ops = family->ops;
-       unsigned int n_ops = family->n_ops;
        int i, j;
 
-       if (WARN_ON(n_ops && !ops))
+       if (WARN_ON(family->n_ops && !family->ops) ||
+           WARN_ON(family->n_small_ops && !family->small_ops))
                return -EINVAL;
 
-       if (!n_ops)
-               return 0;
+       for (i = 0; i < genl_get_cmd_cnt(family); i++) {
+               struct genl_ops op;
 
-       for (i = 0; i < n_ops; i++) {
-               if (ops[i].dumpit == NULL && ops[i].doit == NULL)
+               genl_get_cmd_by_index(i, family, &op);
+               if (op.dumpit == NULL && op.doit == NULL)
                        return -EINVAL;
-               for (j = i + 1; j < n_ops; j++)
-                       if (ops[i].cmd == ops[j].cmd)
+               for (j = i + 1; j < genl_get_cmd_cnt(family); j++) {
+                       struct genl_ops op2;
+
+                       genl_get_cmd_by_index(j, family, &op2);
+                       if (op.cmd == op2.cmd)
                                return -EINVAL;
+               }
        }
 
        return 0;
@@ -524,7 +586,7 @@ no_attrs:
                return -ENOMEM;
        }
        info->family = ctx->family;
-       info->ops = ops;
+       info->op = *ops;
        info->attrs = attrs;
 
        cb->data = info;
@@ -546,7 +608,7 @@ no_attrs:
 
 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 {
-       const struct genl_ops *ops = genl_dumpit_info(cb)->ops;
+       const struct genl_ops *ops = &genl_dumpit_info(cb)->op;
        int rc;
 
        genl_lock();
@@ -558,7 +620,7 @@ static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 static int genl_lock_done(struct netlink_callback *cb)
 {
        const struct genl_dumpit_info *info = genl_dumpit_info(cb);
-       const struct genl_ops *ops = info->ops;
+       const struct genl_ops *ops = &info->op;
        int rc = 0;
 
        if (ops->done) {
@@ -574,7 +636,7 @@ static int genl_lock_done(struct netlink_callback *cb)
 static int genl_parallel_done(struct netlink_callback *cb)
 {
        const struct genl_dumpit_info *info = genl_dumpit_info(cb);
-       const struct genl_ops *ops = info->ops;
+       const struct genl_ops *ops = &info->op;
        int rc = 0;
 
        if (ops->done)
@@ -682,9 +744,9 @@ static int genl_family_rcv_msg(const struct genl_family *family,
                               struct nlmsghdr *nlh,
                               struct netlink_ext_ack *extack)
 {
-       const struct genl_ops *ops;
        struct net *net = sock_net(skb->sk);
        struct genlmsghdr *hdr = nlmsg_data(nlh);
+       struct genl_ops op;
        int hdrlen;
 
        /* this family doesn't exist in this netns */
@@ -695,24 +757,23 @@ static int genl_family_rcv_msg(const struct genl_family *family,
        if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
                return -EINVAL;
 
-       ops = genl_get_cmd(hdr->cmd, family);
-       if (ops == NULL)
+       if (genl_get_cmd(hdr->cmd, family, &op))
                return -EOPNOTSUPP;
 
-       if ((ops->flags & GENL_ADMIN_PERM) &&
+       if ((op.flags & GENL_ADMIN_PERM) &&
            !netlink_capable(skb, CAP_NET_ADMIN))
                return -EPERM;
 
-       if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
+       if ((op.flags & GENL_UNS_ADMIN_PERM) &&
            !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
                return -EPERM;
 
        if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP)
                return genl_family_rcv_msg_dumpit(family, skb, nlh, extack,
-                                                 ops, hdrlen, net);
+                                                 &op, hdrlen, net);
        else
                return genl_family_rcv_msg_doit(family, skb, nlh, extack,
-                                               ops, hdrlen, net);
+                                               &op, hdrlen, net);
 }
 
 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -765,7 +826,7 @@ static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
            nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
                goto nla_put_failure;
 
-       if (family->n_ops) {
+       if (genl_get_cmd_cnt(family)) {
                struct nlattr *nla_ops;
                int i;
 
@@ -773,14 +834,16 @@ static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
                if (nla_ops == NULL)
                        goto nla_put_failure;
 
-               for (i = 0; i < family->n_ops; i++) {
+               for (i = 0; i < genl_get_cmd_cnt(family); i++) {
                        struct nlattr *nest;
-                       const struct genl_ops *ops = &family->ops[i];
-                       u32 op_flags = ops->flags;
+                       struct genl_ops op;
+                       u32 op_flags;
 
-                       if (ops->dumpit)
+                       genl_get_cmd_by_index(i, family, &op);
+                       op_flags = op.flags;
+                       if (op.dumpit)
                                op_flags |= GENL_CMD_CAP_DUMP;
-                       if (ops->doit)
+                       if (op.doit)
                                op_flags |= GENL_CMD_CAP_DO;
                        if (family->policy)
                                op_flags |= GENL_CMD_CAP_HASPOL;
@@ -789,7 +852,7 @@ static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
                        if (nest == NULL)
                                goto nla_put_failure;
 
-                       if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
+                       if (nla_put_u32(skb, CTRL_ATTR_OP_ID, op.cmd) ||
                            nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
                                goto nla_put_failure;