Commit cb0ce18a authored Oct 11, 2019 by Michal Kubecek Committed by David S. Miller Oct 13, 2019

genetlink: do not parse attributes for families with zero maxattr



Commit c10e6cf8 ("net: genetlink: push attrbuf allocation and parsing
to a separate function") moved attribute buffer allocation and attribute
parsing from genl_family_rcv_msg_doit() into a separate function
genl_family_rcv_msg_attrs_parse() which, unlike the previous code, calls
__nlmsg_parse() even if family->maxattr is 0 (i.e. the family does its own
parsing). The parser error is ignored and does not propagate out of
genl_family_rcv_msg_attrs_parse() but an error message ("Unknown attribute
type") is set in extack and if further processing generates no error or
warning, it stays there and is interpreted as a warning by userspace.

Dumpit requests are not affected as genl_family_rcv_msg_dumpit() bypasses
the call of genl_family_rcv_msg_attrs_parse() if family->maxattr is zero.
Move this logic inside genl_family_rcv_msg_attrs_parse() so that we don't
have to handle it in each caller.

v3: put the check inside genl_family_rcv_msg_attrs_parse()
v2: adjust also argument of genl_family_rcv_msg_attrs_free()

Fixes: c10e6cf8 ("net: genetlink: push attrbuf allocation and parsing to a separate function")
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent c208bdb9

net/netlink/genetlink.c

+4 −6

Original line number	Diff line number	Diff line
		@@ -483,6 +483,9 @@ genl_family_rcv_msg_attrs_parse(const struct genl_family *family,
		struct nlattr **attrbuf;
		int err;

		if (!family->maxattr)
		return NULL;

		if (parallel) {
		attrbuf = kmalloc_array(family->maxattr + 1,
		sizeof(struct nlattr *), GFP_KERNEL);
		@@ -582,9 +585,6 @@ static int genl_family_rcv_msg_dumpit(const struct genl_family *family,
		if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
		return -EINVAL;

		if (!family->maxattr)
		goto no_attrs;

		attrs = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
		ops, hdrlen,
		GENL_DONT_VALIDATE_DUMP_STRICT,
		@@ -649,7 +649,6 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
		attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
		ops, hdrlen,
		GENL_DONT_VALIDATE_STRICT,
		family->maxattr &&
		family->parallel_ops);
		if (IS_ERR(attrbuf))
		return PTR_ERR(attrbuf);
		@@ -676,8 +675,7 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
		family->post_doit(ops, skb, &info);

		out:
		genl_family_rcv_msg_attrs_free(family, attrbuf,
		family->maxattr && family->parallel_ops);
		genl_family_rcv_msg_attrs_free(family, attrbuf, family->parallel_ops);

		return err;
		}

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