netdev - [PATCH net-next 05/13] genetlink: check for callback type at op load time

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Message-Id: <20221018230728.1039524-6-kuba@kernel.org>
Date:   Tue, 18 Oct 2022 16:07:20 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     davem@...emloft.net, johannes@...solutions.net
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com,
        jiri@...nulli.us, razor@...ckwall.org, nicolas.dichtel@...nd.com,
        gnault@...hat.com, jacob.e.keller@...el.com, fw@...len.de,
        Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next 05/13] genetlink: check for callback type at op load time

Now that genl_get_cmd_split() is informed what type of callback
user is trying to access (do or dump) we can check that this
callback is indeed available and return an error early.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 net/netlink/genetlink.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 26ddbd23549d..9dfb3cf89b97 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -166,11 +166,17 @@ static int genl_get_cmd(u32 cmd, const struct genl_family *family,
 	return genl_get_cmd_small(cmd, family, op);
 }
 
-static void
+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;
@@ -196,6 +202,8 @@ genl_cmd_full_to_split(struct genl_split_ops *op,
 	op->validate		= full->validate;
 
 	op->flags		|= flags;
+
+	return 0;
 }
 
 static int
@@ -211,9 +219,7 @@ genl_get_cmd_split(u32 cmd, u8 flags, const struct genl_family *family,
 		return err;
 	}
 
-	genl_cmd_full_to_split(op, family, &full, flags);
-
-	return 0;
+	return genl_cmd_full_to_split(op, family, &full, flags);
 }
 
 static void genl_get_cmd_by_index(unsigned int i,
@@ -704,9 +710,6 @@ static int genl_family_rcv_msg_dumpit(const struct genl_family *family,
 	struct genl_start_context ctx;
 	int err;
 
-	if (!ops->dumpit)
-		return -EOPNOTSUPP;
-
 	ctx.family = family;
 	ctx.nlh = nlh;
 	ctx.extack = extack;
@@ -751,9 +754,6 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
 	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);
-- 
2.37.3