Merge branch 'genetlink-per-op-type-policies'

Jakub Kicinski says:

====================
genetlink: support per op type policies

While writing new genetlink families I was increasingly annoyed by the fact
that we don't support different policies for do and dump callbacks.
This makes it hard to do proper input validation for dumps which usually
have a lot more narrow range of accepted attributes.

There is also a minor inconvenience of not supporting different per_doit
and post_doit callbacks per op.

This series addresses those problems by introducing another op format.

v3:
 - minor fixes to patch 12 after I took it for a spin with a real family
 - adjust commit msg in patch 8
v2: https://lore.kernel.org/all/20221102213338.194672-1-kuba@kernel.org/
 - wait for net changes to propagate
 - restore the missing comment in patch 1
 - drop extra space in patch 3
 - improve commit message in patch 4
v1: https://lore.kernel.org/all/20221018230728.1039524-1-kuba@kernel.org/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

7 files changed, 445 insertions, 142 deletions

diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index 9f97f73615b6..d21210709f84 100644
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h
@@ -18,12 +18,11 @@ struct genl_multicast_group {
 	u8			flags;
 };
 
-struct genl_ops;
+struct genl_split_ops;
 struct genl_info;
 
 /**
  * struct genl_family - generic netlink family
- * @id: protocol family identifier (private)
  * @hdrsize: length of user specific header in bytes
  * @name: name of family
  * @version: protocol version
@@ -43,12 +42,13 @@ struct genl_info;
  * @resv_start_op: first operation for which reserved fields of the header
  *	can be validated and policies are required (see below);
  *	new families should leave this field at zero
- * @mcgrp_offset: starting number of multicast group IDs in this family
- *	(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
+ * @split_ops: the split do/dump form of operation definition
+ * @n_split_ops: number of entries in @split_ops, not that with split do/dump
+ *	ops the number of entries is not the same as number of commands
  *
  * Attribute policies (the combination of @policy and @maxattr fields)
  * can be attached at the family level or at the operation level.
@@ -58,29 +58,35 @@ struct genl_info;
  * if policy is not provided core will reject all TLV attributes.
  */
 struct genl_family {
-	int			id;		/* private */
 	unsigned int		hdrsize;
 	char			name[GENL_NAMSIZ];
 	unsigned int		version;
 	unsigned int		maxattr;
-	unsigned int		mcgrp_offset;	/* private */
 	u8			netnsok:1;
 	u8			parallel_ops:1;
 	u8			n_ops;
 	u8			n_small_ops;
+	u8			n_split_ops;
 	u8			n_mcgrps;
 	u8			resv_start_op;
 	const struct nla_policy *policy;
-	int			(*pre_doit)(const struct genl_ops *ops,
+	int			(*pre_doit)(const struct genl_split_ops *ops,
 					    struct sk_buff *skb,
 					    struct genl_info *info);
-	void			(*post_doit)(const struct genl_ops *ops,
+	void			(*post_doit)(const struct genl_split_ops *ops,
 					     struct sk_buff *skb,
 					     struct genl_info *info);
 	const struct genl_ops *	ops;
 	const struct genl_small_ops *small_ops;
+	const struct genl_split_ops *split_ops;
 	const struct genl_multicast_group *mcgrps;
 	struct module		*module;
+
+/* private: internal use only */
+	/* protocol family identifier */
+	int			id;
+	/* starting number of multicast group IDs in this family */
+	unsigned int		mcgrp_offset;
 };
 
 /**
@@ -182,6 +188,58 @@ struct genl_ops {
 };
 
 /**
+ * struct genl_split_ops - generic netlink operations (do/dump split version)
+ * @cmd: command identifier
+ * @internal_flags: flags used by the family
+ * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM)
+ * @validate: validation flags from enum genl_validate_flags
+ * @policy: netlink policy (takes precedence over family policy)
+ * @maxattr: maximum number of attributes supported
+ *
+ * Do callbacks:
+ * @pre_doit: called before an operation's @doit callback, it may
+ *	do additional, common, filtering and return an error
+ * @doit: standard command callback
+ * @post_doit: called after an operation's @doit callback, it may
+ *	undo operations done by pre_doit, for example release locks
+ *
+ * Dump callbacks:
+ * @start: start callback for dumps
+ * @dumpit: callback for dumpers
+ * @done: completion callback for dumps
+ *
+ * Do callbacks can be used if %GENL_CMD_CAP_DO is set in @flags.
+ * Dump callbacks can be used if %GENL_CMD_CAP_DUMP is set in @flags.
+ * Exactly one of those flags must be set.
+ */
+struct genl_split_ops {
+	union {
+		struct {
+			int (*pre_doit)(const struct genl_split_ops *ops,
+					struct sk_buff *skb,
+					struct genl_info *info);
+			int (*doit)(struct sk_buff *skb,
+				    struct genl_info *info);
+			void (*post_doit)(const struct genl_split_ops *ops,
+					  struct sk_buff *skb,
+					  struct genl_info *info);
+		};
+		struct {
+			int (*start)(struct netlink_callback *cb);
+			int (*dumpit)(struct sk_buff *skb,
+				      struct netlink_callback *cb);
+			int (*done)(struct netlink_callback *cb);
+		};
+	};
+	const struct nla_policy *policy;
+	unsigned int		maxattr;
+	u8			cmd;
+	u8			internal_flags;
+	u8			flags;
+	u8			validate;
+};
+
+/**
  * struct genl_dumpit_info - info that is available during dumpit op call
  * @family: generic netlink family - for internal genl code usage
  * @op: generic netlink ops - for internal genl code usage
@@ -189,7 +247,7 @@ struct genl_ops {
  */
 struct genl_dumpit_info {
 	const struct genl_family *family;
-	struct genl_ops op;
+	struct genl_split_ops op;
 	struct nlattr **attrs;
 };
 
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index a5e4a4e976cf..ad5714f737be 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -1267,7 +1267,8 @@ batadv_get_vlan_from_info(struct batadv_priv *bat_priv, struct net *net,
  *
  * Return: 0 on success or negative error number in case of failure
  */
-static int batadv_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
+static int batadv_pre_doit(const struct genl_split_ops *ops,
+			   struct sk_buff *skb,
 			   struct genl_info *info)
 {
 	struct net *net = genl_info_net(info);
@@ -1332,7 +1333,8 @@ err_put_softif:
  * @skb: Netlink message with request data
  * @info: receiver information
  */
-static void batadv_post_doit(const struct genl_ops *ops, struct sk_buff *skb,
+static void batadv_post_doit(const struct genl_split_ops *ops,
+			     struct sk_buff *skb,
 			     struct genl_info *info)
 {
 	struct batadv_hard_iface *hard_iface;
diff --git a/net/core/devlink.c b/net/core/devlink.c
index 2dcf2bcc3527..40fcdded57e6 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -770,7 +770,7 @@ devlink_region_snapshot_get_by_id(struct devlink_region *region, u32 id)
 #define DEVLINK_NL_FLAG_NEED_RATE_NODE		BIT(3)
 #define DEVLINK_NL_FLAG_NEED_LINECARD		BIT(4)
 
-static int devlink_nl_pre_doit(const struct genl_ops *ops,
+static int devlink_nl_pre_doit(const struct genl_split_ops *ops,
 			       struct sk_buff *skb, struct genl_info *info)
 {
 	struct devlink_linecard *linecard;
@@ -828,7 +828,7 @@ unlock:
 	return err;
 }
 
-static void devlink_nl_post_doit(const struct genl_ops *ops,
+static void devlink_nl_post_doit(const struct genl_split_ops *ops,
 				 struct sk_buff *skb, struct genl_info *info)
 {
 	struct devlink_linecard *linecard;
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 11aa6e8a3098..5a782d1d8fd3 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -1620,7 +1620,7 @@ static const struct genl_small_ops dropmon_ops[] = {
 	},
 };
 
-static int net_dm_nl_pre_doit(const struct genl_ops *ops,
+static int net_dm_nl_pre_doit(const struct genl_split_ops *ops,
 			      struct sk_buff *skb, struct genl_info *info)
 {
 	mutex_lock(&net_dm_mutex);
@@ -1628,7 +1628,7 @@ static int net_dm_nl_pre_doit(const struct genl_ops *ops,
 	return 0;
 }
 
-static void net_dm_nl_post_doit(const struct genl_ops *ops,
+static void net_dm_nl_post_doit(const struct genl_split_ops *ops,
 				struct sk_buff *skb, struct genl_info *info)
 {
 	mutex_unlock(&net_dm_mutex);
diff --git a/net/ieee802154/nl802154.c b/net/ieee802154/nl802154.c
index 38c4f3cb010e..b33d1b5eda87 100644
--- a/net/ieee802154/nl802154.c
+++ b/net/ieee802154/nl802154.c
@@ -2157,7 +2157,8 @@ static int nl802154_del_llsec_seclevel(struct sk_buff *skb,
 #define NL802154_FLAG_CHECK_NETDEV_UP	0x08
 #define NL802154_FLAG_NEED_WPAN_DEV	0x10
 
-static int nl802154_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
+static int nl802154_pre_doit(const struct genl_split_ops *ops,
+			     struct sk_buff *skb,
 			     struct genl_info *info)
 {
 	struct cfg802154_registered_device *rdev;
@@ -2219,7 +2220,8 @@ static int nl802154_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
 	return 0;
 }
 
-static void nl802154_post_doit(const struct genl_ops *ops, struct sk_buff *skb,
+static void nl802154_post_doit(const struct genl_split_ops *ops,
+			       struct sk_buff *skb,
 			       struct genl_info *info)
 {
 	if (info->user_ptr[1]) {
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 3e16527beb91..362a61179036 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -101,6 +101,17 @@ genl_op_fill_in_reject_policy(const struct genl_family *family,
 	op->maxattr = 1;
 }
 
+static void
+genl_op_fill_in_reject_policy_split(const struct genl_family *family,
+				    struct genl_split_ops *op)
+{
+	if (op->policy)
+		return;
+
+	op->policy = genl_policy_reject_all;
+	op->maxattr = 1;
+}
+
 static const struct genl_family *genl_family_find_byid(unsigned int id)
 {
 	return idr_find(&genl_fam_idr, id);
@@ -118,10 +129,15 @@ static const struct genl_family *genl_family_find_byname(char *name)
 	return NULL;
 }
 
-static int genl_get_cmd_cnt(const struct genl_family *family)
-{
-	return family->n_ops + family->n_small_ops;
-}
+struct genl_op_iter {
+	const struct genl_family *family;
+	struct genl_split_ops doit;
+	struct genl_split_ops dumpit;
+	int cmd_idx;
+	int entry_idx;
+	u32 cmd;
+	u8 flags;
+};
 
 static void genl_op_from_full(const struct genl_family *family,
 			      unsigned int i, struct genl_ops *op)
@@ -181,24 +197,171 @@ static int genl_get_cmd_small(u32 cmd, const struct genl_family *family,
 	return -ENOENT;
 }
 
-static int genl_get_cmd(u32 cmd, const struct genl_family *family,
-			struct genl_ops *op)
+static void genl_op_from_split(struct genl_op_iter *iter)
 {
-	if (!genl_get_cmd_full(cmd, family, op))
-		return 0;
-	return genl_get_cmd_small(cmd, family, op);
+	const struct genl_family *family = iter->family;
+	int i, cnt = 0;
+
+	i = iter->entry_idx - family->n_ops - family->n_small_ops;
+
+	if (family->split_ops[i + cnt].flags & GENL_CMD_CAP_DO) {
+		iter->doit = family->split_ops[i + cnt];
+		genl_op_fill_in_reject_policy_split(family, &iter->doit);
+		cnt++;
+	} else {
+		memset(&iter->doit, 0, sizeof(iter->doit));
+	}
+
+	if (i + cnt < family->n_split_ops &&
+	    family->split_ops[i + cnt].flags & GENL_CMD_CAP_DUMP) {
+		iter->dumpit = family->split_ops[i + cnt];
+		genl_op_fill_in_reject_policy_split(family, &iter->dumpit);
+		cnt++;
+	} else {
+		memset(&iter->dumpit, 0, sizeof(iter->dumpit));
+	}
+
+	WARN_ON(!cnt);
+	iter->entry_idx += cnt;
 }
 
-static void genl_get_cmd_by_index(unsigned int i,
-				  const struct genl_family *family,
-				  struct genl_ops *op)
+static int
+genl_get_cmd_split(u32 cmd, u8 flag, const struct genl_family *family,
+		   struct genl_split_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);
+	int i;
+
+	for (i = 0; i < family->n_split_ops; i++)
+		if (family->split_ops[i].cmd == cmd &&
+		    family->split_ops[i].flags & flag) {
+			*op = family->split_ops[i];
+			return 0;
+		}
+
+	return -ENOENT;
+}
+
+static int
+genl_cmd_full_to_split(struct genl_split_ops *op,
+		       const struct genl_family *family,
+		       const struct genl_ops *full, u8 flags)
+{
+	if ((flags & GENL_CMD_CAP_DO && !full->doit) ||
+	    (flags & GENL_CMD_CAP_DUMP && !full->dumpit)) {
+		memset(op, 0, sizeof(*op));
+		return -ENOENT;
+	}
+
+	if (flags & GENL_CMD_CAP_DUMP) {
+		op->start	= full->start;
+		op->dumpit	= full->dumpit;
+		op->done	= full->done;
+	} else {
+		op->pre_doit	= family->pre_doit;
+		op->doit	= full->doit;
+		op->post_doit	= family->post_doit;
+	}
+
+	if (flags & GENL_CMD_CAP_DUMP &&
+	    full->validate & GENL_DONT_VALIDATE_DUMP) {
+		op->policy	= NULL;
+		op->maxattr	= 0;
+	} else {
+		op->policy	= full->policy;
+		op->maxattr	= full->maxattr;
+	}
+
+	op->cmd			= full->cmd;
+	op->internal_flags	= full->internal_flags;
+	op->flags		= full->flags;
+	op->validate		= full->validate;
+
+	/* Make sure flags include the GENL_CMD_CAP_DO / GENL_CMD_CAP_DUMP */
+	op->flags		|= flags;
+
+	return 0;
+}
+
+static int
+genl_get_cmd(u32 cmd, u8 flags, const struct genl_family *family,
+	     struct genl_split_ops *op)
+{
+	struct genl_ops full;
+	int err;
+
+	err = genl_get_cmd_full(cmd, family, &full);
+	if (err == -ENOENT)
+		err = genl_get_cmd_small(cmd, family, &full);
+	/* Found one of legacy forms */
+	if (err == 0)
+		return genl_cmd_full_to_split(op, family, &full, flags);
+
+	err = genl_get_cmd_split(cmd, flags, family, op);
+	if (err)
+		memset(op, 0, sizeof(*op));
+	return err;
+}
+
+static bool
+genl_op_iter_init(const struct genl_family *family, struct genl_op_iter *iter)
+{
+	iter->family = family;
+	iter->cmd_idx = 0;
+	iter->entry_idx = 0;
+
+	iter->flags = 0;
+
+	return iter->family->n_ops +
+		iter->family->n_small_ops +
+		iter->family->n_split_ops;
+}
+
+static bool genl_op_iter_next(struct genl_op_iter *iter)
+{
+	const struct genl_family *family = iter->family;
+	bool legacy_op = true;
+	struct genl_ops op;
+
+	if (iter->entry_idx < family->n_ops) {
+		genl_op_from_full(family, iter->entry_idx, &op);
+	} else if (iter->entry_idx < family->n_ops + family->n_small_ops) {
+		genl_op_from_small(family, iter->entry_idx - family->n_ops,
+				   &op);
+	} else if (iter->entry_idx <
+		   family->n_ops + family->n_small_ops + family->n_split_ops) {
+		legacy_op = false;
+		/* updates entry_idx */
+		genl_op_from_split(iter);
+	} else {
+		return false;
+	}
+
+	iter->cmd_idx++;
+
+	if (legacy_op) {
+		iter->entry_idx++;
+
+		genl_cmd_full_to_split(&iter->doit, family,
+				       &op, GENL_CMD_CAP_DO);
+		genl_cmd_full_to_split(&iter->dumpit, family,
+				       &op, GENL_CMD_CAP_DUMP);
+	}
+
+	iter->cmd = iter->doit.cmd | iter->dumpit.cmd;
+	iter->flags = iter->doit.flags | iter->dumpit.flags;
+
+	return true;
+}
+
+static void
+genl_op_iter_copy(struct genl_op_iter *dst, struct genl_op_iter *src)
+{
+	*dst = *src;
+}
+
+static unsigned int genl_op_iter_idx(struct genl_op_iter *iter)
+{
+	return iter->cmd_idx;
 }
 
 static int genl_allocate_reserve_groups(int n_groups, int *first_id)
@@ -366,31 +529,72 @@ static void genl_unregister_mc_groups(const struct genl_family *family)
 	}
 }
 
+static bool genl_split_op_check(const struct genl_split_ops *op)
+{
+	if (WARN_ON(hweight8(op->flags & (GENL_CMD_CAP_DO |
+					  GENL_CMD_CAP_DUMP)) != 1))
+		return true;
+	return false;
+}
+
 static int genl_validate_ops(const struct genl_family *family)
 {
-	int i, j;
+	struct genl_op_iter i, j;
+	unsigned int s;
 
 	if (WARN_ON(family->n_ops && !family->ops) ||
-	    WARN_ON(family->n_small_ops && !family->small_ops))
+	    WARN_ON(family->n_small_ops && !family->small_ops) ||
+	    WARN_ON(family->n_split_ops && !family->split_ops))
 		return -EINVAL;
 
-	for (i = 0; i < genl_get_cmd_cnt(family); i++) {
-		struct genl_ops op;
-
-		genl_get_cmd_by_index(i, family, &op);
-		if (op.dumpit == NULL && op.doit == NULL)
+	for (genl_op_iter_init(family, &i); genl_op_iter_next(&i); ) {
+		if (!(i.flags & (GENL_CMD_CAP_DO | GENL_CMD_CAP_DUMP)))
 			return -EINVAL;
-		if (WARN_ON(op.cmd >= family->resv_start_op && op.validate))
+
+		if (WARN_ON(i.cmd >= family->resv_start_op &&
+			    (i.doit.validate || i.dumpit.validate)))
 			return -EINVAL;
-		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)
+		genl_op_iter_copy(&j, &i);
+		while (genl_op_iter_next(&j)) {
+			if (i.cmd == j.cmd)
 				return -EINVAL;
 		}
 	}
 
+	if (family->n_split_ops) {
+		if (genl_split_op_check(&family->split_ops[0]))
+			return -EINVAL;
+	}
+
+	for (s = 1; s < family->n_split_ops; s++) {
+		const struct genl_split_ops *a, *b;
+
+		a = &family->split_ops[s - 1];
+		b = &family->split_ops[s];
+
+		if (genl_split_op_check(b))
+			return -EINVAL;
+
+		/* Check sort order */
+		if (a->cmd < b->cmd)
+			continue;
+
+		if (a->internal_flags != b->internal_flags ||
+		    ((a->flags ^ b->flags) & ~(GENL_CMD_CAP_DO |
+					       GENL_CMD_CAP_DUMP))) {
+			WARN_ON(1);
+			return -EINVAL;
+		}
+
+		if ((a->flags & GENL_CMD_CAP_DO) &&
+		    (b->flags & GENL_CMD_CAP_DUMP))
+			continue;
+
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -544,7 +748,7 @@ static struct nlattr **
 genl_family_rcv_msg_attrs_parse(const struct genl_family *family,
 				struct nlmsghdr *nlh,
 				struct netlink_ext_ack *extack,
-				const struct genl_ops *ops,
+				const struct genl_split_ops *ops,
 				int hdrlen,
 				enum genl_validate_flags no_strict_flag)
 {
@@ -580,22 +784,21 @@ struct genl_start_context {
 	const struct genl_family *family;
 	struct nlmsghdr *nlh;
 	struct netlink_ext_ack *extack;
-	const struct genl_ops *ops;
+	const struct genl_split_ops *ops;
 	int hdrlen;
 };
 
 static int genl_start(struct netlink_callback *cb)
 {
 	struct genl_start_context *ctx = cb->data;
-	const struct genl_ops *ops = ctx->ops;
+	const struct genl_split_ops *ops;
 	struct genl_dumpit_info *info;
 	struct nlattr **attrs = NULL;
 	int rc = 0;
 
-	if (ops->validate & GENL_DONT_VALIDATE_DUMP)
-		goto no_attrs;
-
-	if (ctx->nlh->nlmsg_len < nlmsg_msg_size(ctx->hdrlen))
+	ops = ctx->ops;
+	if (!(ops->validate & GENL_DONT_VALIDATE_DUMP) &&
+	    ctx->nlh->nlmsg_len < nlmsg_msg_size(ctx->hdrlen))
 		return -EINVAL;
 
 	attrs = genl_family_rcv_msg_attrs_parse(ctx->family, ctx->nlh, ctx->extack,
@@ -604,7 +807,6 @@ static int genl_start(struct netlink_callback *cb)
 	if (IS_ERR(attrs))
 		return PTR_ERR(attrs);
 
-no_attrs:
 	info = genl_dumpit_info_alloc();
 	if (!info) {
 		genl_family_rcv_msg_attrs_free(attrs);
@@ -633,7 +835,7 @@ no_attrs:
 
 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 {
-	const struct genl_ops *ops = &genl_dumpit_info(cb)->op;
+	const struct genl_split_ops *ops = &genl_dumpit_info(cb)->op;
 	int rc;
 
 	genl_lock();
@@ -645,7 +847,7 @@ 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->op;
+	const struct genl_split_ops *ops = &info->op;
 	int rc = 0;
 
 	if (ops->done) {
@@ -661,7 +863,7 @@ 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->op;
+	const struct genl_split_ops *ops = &info->op;
 	int rc = 0;
 
 	if (ops->done)
@@ -675,15 +877,12 @@ static int genl_family_rcv_msg_dumpit(const struct genl_family *family,
 				      struct sk_buff *skb,
 				      struct nlmsghdr *nlh,
 				      struct netlink_ext_ack *extack,
-				      const struct genl_ops *ops,
+				      const struct genl_split_ops *ops,
 				      int hdrlen, struct net *net)
 {
 	struct genl_start_context ctx;
 	int err;
 
-	if (!ops->dumpit)
-		return -EOPNOTSUPP;
-
 	ctx.family = family;
 	ctx.nlh = nlh;
 	ctx.extack = extack;
@@ -721,16 +920,13 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
 				    struct sk_buff *skb,
 				    struct nlmsghdr *nlh,
 				    struct netlink_ext_ack *extack,
-				    const struct genl_ops *ops,
+				    const struct genl_split_ops *ops,
 				    int hdrlen, struct net *net)
 {
 	struct nlattr **attrbuf;
 	struct genl_info info;
 	int err;
 
-	if (!ops->doit)
-		return -EOPNOTSUPP;
-
 	attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
 						  ops, hdrlen,
 						  GENL_DONT_VALIDATE_STRICT);
@@ -747,16 +943,16 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
 	genl_info_net_set(&info, net);
 	memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 
-	if (family->pre_doit) {
-		err = family->pre_doit(ops, skb, &info);
+	if (ops->pre_doit) {
+		err = ops->pre_doit(ops, skb, &info);
 		if (err)
 			goto out;
 	}
 
 	err = ops->doit(skb, &info);
 
-	if (family->post_doit)
-		family->post_doit(ops, skb, &info);
+	if (ops->post_doit)
+		ops->post_doit(ops, skb, &info);
 
 out:
 	genl_family_rcv_msg_attrs_free(attrbuf);
@@ -801,8 +997,9 @@ static int genl_family_rcv_msg(const struct genl_family *family,
 {
 	struct net *net = sock_net(skb->sk);
 	struct genlmsghdr *hdr = nlmsg_data(nlh);
-	struct genl_ops op;
+	struct genl_split_ops op;
 	int hdrlen;
+	u8 flags;
 
 	/* this family doesn't exist in this netns */
 	if (!family->netnsok && !net_eq(net, &init_net))
@@ -815,7 +1012,9 @@ static int genl_family_rcv_msg(const struct genl_family *family,
 	if (genl_header_check(family, nlh, hdr, extack))
 		return -EINVAL;
 
-	if (genl_get_cmd(hdr->cmd, family, &op))
+	flags = (nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP ?
+		GENL_CMD_CAP_DUMP : GENL_CMD_CAP_DO;
+	if (genl_get_cmd(hdr->cmd, flags, family, &op))
 		return -EOPNOTSUPP;
 
 	if ((op.flags & GENL_ADMIN_PERM) &&
@@ -826,7 +1025,7 @@ static int genl_family_rcv_msg(const struct genl_family *family,
 	    !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
-	if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP)
+	if (flags & GENL_CMD_CAP_DUMP)
 		return genl_family_rcv_msg_dumpit(family, skb, nlh, extack,
 						  &op, hdrlen, net);
 	else
@@ -871,6 +1070,7 @@ static struct genl_family genl_ctrl;
 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
 			  u32 flags, struct sk_buff *skb, u8 cmd)
 {
+	struct genl_op_iter i;
 	void *hdr;
 
 	hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
@@ -884,33 +1084,26 @@ 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 (genl_get_cmd_cnt(family)) {
+	if (genl_op_iter_init(family, &i)) {
 		struct nlattr *nla_ops;
-		int i;
 
 		nla_ops = nla_nest_start_noflag(skb, CTRL_ATTR_OPS);
 		if (nla_ops == NULL)
 			goto nla_put_failure;
 
-		for (i = 0; i < genl_get_cmd_cnt(family); i++) {
+		while (genl_op_iter_next(&i)) {
 			struct nlattr *nest;
-			struct genl_ops op;
 			u32 op_flags;
 
-			genl_get_cmd_by_index(i, family, &op);
-			op_flags = op.flags;
-			if (op.dumpit)
-				op_flags |= GENL_CMD_CAP_DUMP;
-			if (op.doit)
-				op_flags |= GENL_CMD_CAP_DO;
-			if (op.policy)
+			op_flags = i.flags;
+			if (i.doit.policy || i.dumpit.policy)
 				op_flags |= GENL_CMD_CAP_HASPOL;
 
-			nest = nla_nest_start_noflag(skb, i + 1);
+			nest = nla_nest_start_noflag(skb, genl_op_iter_idx(&i));
 			if (nest == NULL)
 				goto nla_put_failure;
 
-			if (nla_put_u32(skb, CTRL_ATTR_OP_ID, op.cmd) ||
+			if (nla_put_u32(skb, CTRL_ATTR_OP_ID, i.cmd) ||
 			    nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 				goto nla_put_failure;
 
@@ -1163,10 +1356,10 @@ static int genl_ctrl_event(int event, const struct genl_family *family,
 struct ctrl_dump_policy_ctx {
 	struct netlink_policy_dump_state *state;
 	const struct genl_family *rt;
-	unsigned int opidx;
+	struct genl_op_iter *op_iter;
 	u32 op;
 	u16 fam_id;
-	u8 policies:1,
+	u8 dump_map:1,
 	   single_op:1;
 };
 
@@ -1183,8 +1376,8 @@ static int ctrl_dumppolicy_start(struct netlink_callback *cb)
 	struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx;
 	struct nlattr **tb = info->attrs;
 	const struct genl_family *rt;
-	struct genl_ops op;
-	int err, i;
+	struct genl_op_iter i;
+	int err;
 
 	BUILD_BUG_ON(sizeof(*ctx) > sizeof(cb->ctx));
 
@@ -1208,40 +1401,71 @@ static int ctrl_dumppolicy_start(struct netlink_callback *cb)
 	ctx->rt = rt;
 
 	if (tb[CTRL_ATTR_OP]) {
+		struct genl_split_ops doit, dump;
+
 		ctx->single_op = true;
 		ctx->op = nla_get_u32(tb[CTRL_ATTR_OP]);
 
-		err = genl_get_cmd(ctx->op, rt, &op);
-		if (err) {
+		if (genl_get_cmd(ctx->op, GENL_CMD_CAP_DO, rt, &doit) &&
+		    genl_get_cmd(ctx->op, GENL_CMD_CAP_DUMP, rt, &dump)) {
 			NL_SET_BAD_ATTR(cb->extack, tb[CTRL_ATTR_OP]);
-			return err;
+			return -ENOENT;
+		}
+
+		if (doit.policy) {
+			err = netlink_policy_dump_add_policy(&ctx->state,
+							     doit.policy,
+							     doit.maxattr);
+			if (err)
+				goto err_free_state;
+		}
+		if (dump.policy) {
+			err = netlink_policy_dump_add_policy(&ctx->state,
+							     dump.policy,
+							     dump.maxattr);
+			if (err)
+				goto err_free_state;
 		}
 
-		if (!op.policy)
+		if (!ctx->state)
 			return -ENODATA;
 
-		return netlink_policy_dump_add_policy(&ctx->state, op.policy,
-						      op.maxattr);
+		ctx->dump_map = 1;
+		return 0;
 	}
 
-	for (i = 0; i < genl_get_cmd_cnt(rt); i++) {
-		genl_get_cmd_by_index(i, rt, &op);
+	ctx->op_iter = kmalloc(sizeof(*ctx->op_iter), GFP_KERNEL);
+	if (!ctx->op_iter)
+		return -ENOMEM;
+	ctx->dump_map = genl_op_iter_init(rt, ctx->op_iter);
 
-		if (op.policy) {
+	for (genl_op_iter_init(rt, &i); genl_op_iter_next(&i); ) {
+		if (i.doit.policy) {
+			err = netlink_policy_dump_add_policy(&ctx->state,
+							     i.doit.policy,
+							     i.doit.maxattr);
+			if (err)
+				goto err_free_state;
+		}
+		if (i.dumpit.policy) {
 			err = netlink_policy_dump_add_policy(&ctx->state,
-							     op.policy,
-							     op.maxattr);
+							     i.dumpit.policy,
+							     i.dumpit.maxattr);
 			if (err)
 				goto err_free_state;
 		}
 	}
 
-	if (!ctx->state)
-		return -ENODATA;
+	if (!ctx->state) {
+		err = -ENODATA;
+		goto err_free_op_iter;
+	}
 	return 0;
 
 err_free_state:
 	netlink_policy_dump_free(ctx->state);
+err_free_op_iter:
+	kfree(ctx->op_iter);
 	return err;
 }
 
@@ -1265,7 +1489,8 @@ static void *ctrl_dumppolicy_prep(struct sk_buff *skb,
 
 static int ctrl_dumppolicy_put_op(struct sk_buff *skb,
 				  struct netlink_callback *cb,
-			          struct genl_ops *op)
+				  struct genl_split_ops *doit,
+				  struct genl_split_ops *dumpit)
 {
 	struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx;
 	struct nlattr *nest_pol, *nest_op;
@@ -1273,10 +1498,7 @@ static int ctrl_dumppolicy_put_op(struct sk_buff *skb,
 	int idx;
 
 	/* skip if we have nothing to show */
-	if (!op->policy)
-		return 0;
-	if (!op->doit &&
-	    (!op->dumpit || op->validate & GENL_DONT_VALIDATE_DUMP))
+	if (!doit->policy && !dumpit->policy)
 		return 0;
 
 	hdr = ctrl_dumppolicy_prep(skb, cb);
@@ -1287,21 +1509,26 @@ static int ctrl_dumppolicy_put_op(struct sk_buff *skb,
 	if (!nest_pol)
 		goto err;
 
-	nest_op = nla_nest_start(skb, op->cmd);
+	nest_op = nla_nest_start(skb, doit->cmd);
 	if (!nest_op)
 		goto err;
 
-	/* for now both do/dump are always the same */
-	idx = netlink_policy_dump_get_policy_idx(ctx->state,
-						 op->policy,
-						 op->maxattr);
+	if (doit->policy) {
+		idx = netlink_policy_dump_get_policy_idx(ctx->state,
+							 doit->policy,
+							 doit->maxattr);
 
-	if (op->doit && nla_put_u32(skb, CTRL_ATTR_POLICY_DO, idx))
-		goto err;
+		if (nla_put_u32(skb, CTRL_ATTR_POLICY_DO, idx))
+			goto err;
+	}
+	if (dumpit->policy) {
+		idx = netlink_policy_dump_get_policy_idx(ctx->state,
+							 dumpit->policy,
+							 dumpit->maxattr);
 
-	if (op->dumpit && !(op->validate & GENL_DONT_VALIDATE_DUMP) &&
-	    nla_put_u32(skb, CTRL_ATTR_POLICY_DUMP, idx))
-		goto err;
+		if (nla_put_u32(skb, CTRL_ATTR_POLICY_DUMP, idx))
+			goto err;
+	}
 
 	nla_nest_end(skb, nest_op);
 	nla_nest_end(skb, nest_pol);
@@ -1318,31 +1545,33 @@ static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb)
 	struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx;
 	void *hdr;
 
-	if (!ctx->policies) {
-		while (ctx->opidx < genl_get_cmd_cnt(ctx->rt)) {
-			struct genl_ops op;
-
-			if (ctx->single_op) {
-				int err;
-
-				err = genl_get_cmd(ctx->op, ctx->rt, &op);
-				if (WARN_ON(err))
-					return skb->len;
+	if (ctx->dump_map) {
+		if (ctx->single_op) {
+			struct genl_split_ops doit, dumpit;
 
-				/* break out of the loop after this one */
-				ctx->opidx = genl_get_cmd_cnt(ctx->rt);
-			} else {
-				genl_get_cmd_by_index(ctx->opidx, ctx->rt, &op);
+			if (genl_get_cmd(ctx->op, GENL_CMD_CAP_DO,
+					 ctx->rt, &doit) &&
+			    genl_get_cmd(ctx->op, GENL_CMD_CAP_DUMP,
+					 ctx->rt, &dumpit)) {
+				WARN_ON(1);
+				return -ENOENT;
 			}
 
-			if (ctrl_dumppolicy_put_op(skb, cb, &op))
+			if (ctrl_dumppolicy_put_op(skb, cb, &doit, &dumpit))
 				return skb->len;
 
-			ctx->opidx++;
+			/* done with the per-op policy index list */
+			ctx->dump_map = 0;
 		}
 
-		/* completed with the per-op policy index list */
-		ctx->policies = true;
+		while (ctx->dump_map) {
+			if (ctrl_dumppolicy_put_op(skb, cb,
+						   &ctx->op_iter->doit,
+						   &ctx->op_iter->dumpit))
+				return skb->len;
+
+			ctx->dump_map = genl_op_iter_next(ctx->op_iter);
+		}
 	}
 
 	while (netlink_policy_dump_loop(ctx->state)) {
@@ -1375,18 +1604,27 @@ static int ctrl_dumppolicy_done(struct netlink_callback *cb)
 {
 	struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx;
 
+	kfree(ctx->op_iter);
 	netlink_policy_dump_free(ctx->state);
 	return 0;
 }
 
-static const struct genl_ops genl_ctrl_ops[] = {
+static const struct genl_split_ops genl_ctrl_ops[] = {
 	{
 		.cmd		= CTRL_CMD_GETFAMILY,
-		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.validate	= GENL_DONT_VALIDATE_STRICT,
 		.policy		= ctrl_policy_family,
 		.maxattr	= ARRAY_SIZE(ctrl_policy_family) - 1,
 		.doit		= ctrl_getfamily,
+		.flags		= GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd		= CTRL_CMD_GETFAMILY,
+		.validate	= GENL_DONT_VALIDATE_DUMP,
+		.policy		= ctrl_policy_family,
+		.maxattr	= ARRAY_SIZE(ctrl_policy_family) - 1,
 		.dumpit		= ctrl_dumpfamily,
+		.flags		= GENL_CMD_CAP_DUMP,
 	},
 	{
 		.cmd		= CTRL_CMD_GETPOLICY,
@@ -1395,6 +1633,7 @@ static const struct genl_ops genl_ctrl_ops[] = {
 		.start		= ctrl_dumppolicy_start,
 		.dumpit		= ctrl_dumppolicy,
 		.done		= ctrl_dumppolicy_done,
+		.flags		= GENL_CMD_CAP_DUMP,
 	},
 };
 
@@ -1404,8 +1643,8 @@ static const struct genl_multicast_group genl_ctrl_groups[] = {
 
 static struct genl_family genl_ctrl __ro_after_init = {
 	.module = THIS_MODULE,
-	.ops = genl_ctrl_ops,
-	.n_ops = ARRAY_SIZE(genl_ctrl_ops),
+	.split_ops = genl_ctrl_ops,
+	.n_split_ops = ARRAY_SIZE(genl_ctrl_ops),
 	.resv_start_op = CTRL_CMD_GETPOLICY + 1,
 	.mcgrps = genl_ctrl_groups,
 	.n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 148f66edb015..1ad0326ff4dc 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -16140,7 +16140,8 @@ static u32 nl80211_internal_flags[] = {
 #undef SELECTOR
 };
 
-static int nl80211_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
+static int nl80211_pre_doit(const struct genl_split_ops *ops,
+			    struct sk_buff *skb,
 			    struct genl_info *info)
 {
 	struct cfg80211_registered_device *rdev = NULL;
@@ -16241,7 +16242,8 @@ out_unlock:
 	return err;
 }
 
-static void nl80211_post_doit(const struct genl_ops *ops, struct sk_buff *skb,
+static void nl80211_post_doit(const struct genl_split_ops *ops,
+			      struct sk_buff *skb,
 			      struct genl_info *info)
 {
 	u32 internal_flags = nl80211_internal_flags[ops->internal_flags];