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rtnetlink: Move input checking for rtnl_fdb_dump to helper

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Move the existing input checking for rtnl_fdb_dump into a helper,
valid_fdb_dump_legacy. This function will retain the current
logic that works around the 2 headers that userspace has been
allowed to send up to this point.

Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Christian Brauner <christian@brauner.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Ahern 2018-10-07 20:16:43 -07:00 committed by David S. Miller
parent c77b93641e
commit 8dfbda19a2
1 changed files with 36 additions and 23 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

59
net/core/rtnetlink.c
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@ -3799,14 +3799,44 @@ int ndo_dflt_fdb_dump(struct sk_buff *skb,
}
EXPORT_SYMBOL(ndo_dflt_fdb_dump);
static int valid_fdb_dump_legacy(const struct nlmsghdr *nlh,
int *br_idx, int *brport_idx,
struct netlink_ext_ack *extack)
{
struct ifinfomsg *ifm = nlmsg_data(nlh);
struct nlattr *tb[IFLA_MAX+1];
int err;
/* A hack to preserve kernel<->userspace interface.
* Before Linux v4.12 this code accepted ndmsg since iproute2 v3.3.0.
* However, ndmsg is shorter than ifinfomsg thus nlmsg_parse() bails.
* So, check for ndmsg with an optional u32 attribute (not used here).
* Fortunately these sizes don't conflict with the size of ifinfomsg
* with an optional attribute.
*/
if (nlmsg_len(nlh) != sizeof(struct ndmsg) &&
(nlmsg_len(nlh) != sizeof(struct ndmsg) +
nla_attr_size(sizeof(u32)))) {
err = nlmsg_parse(nlh, sizeof(struct ifinfomsg), tb, IFLA_MAX,
ifla_policy, extack);
if (err < 0) {
return -EINVAL;
} else if (err == 0) {
if (tb[IFLA_MASTER])
*br_idx = nla_get_u32(tb[IFLA_MASTER]);
}
*brport_idx = ifm->ifi_index;
}
return 0;
}
static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
struct net_device *dev;
struct nlattr *tb[IFLA_MAX+1];
struct net_device *br_dev = NULL;
const struct net_device_ops *ops = NULL;
const struct net_device_ops *cops = NULL;
struct ifinfomsg *ifm = nlmsg_data(cb->nlh);
struct net *net = sock_net(skb->sk);
struct hlist_head *head;
int brport_idx = 0;
@ -3816,27 +3846,10 @@ static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
int err = 0;
int fidx = 0;
/* A hack to preserve kernel<->userspace interface.
* Before Linux v4.12 this code accepted ndmsg since iproute2 v3.3.0.
* However, ndmsg is shorter than ifinfomsg thus nlmsg_parse() bails.
* So, check for ndmsg with an optional u32 attribute (not used here).
* Fortunately these sizes don't conflict with the size of ifinfomsg
* with an optional attribute.
*/
if (nlmsg_len(cb->nlh) != sizeof(struct ndmsg) &&
(nlmsg_len(cb->nlh) != sizeof(struct ndmsg) +
nla_attr_size(sizeof(u32)))) {
err = nlmsg_parse(cb->nlh, sizeof(struct ifinfomsg), tb,
IFLA_MAX, ifla_policy, cb->extack);
if (err < 0) {
return -EINVAL;
} else if (err == 0) {
if (tb[IFLA_MASTER])
br_idx = nla_get_u32(tb[IFLA_MASTER]);
}
brport_idx = ifm->ifi_index;
}
err = valid_fdb_dump_legacy(cb->nlh, &br_idx, &brport_idx,
cb->extack);
if (err < 0)
return err;
if (br_idx) {
br_dev = __dev_get_by_index(net, br_idx);