rtnetlink: move validate_linkmsg out of do_setlink

This patch moves validate_linkmsg() out of do_setlink() to its callers
and deletes the early validate_linkmsg() call in __rtnl_newlink(), so
that it will not call validate_linkmsg() twice in either of the paths:

  - __rtnl_newlink() -> do_setlink()
  - __rtnl_newlink() -> rtnl_newlink_create() -> rtnl_create_link()

Additionally, as validate_linkmsg() is now only called with a real
dev, we can remove the NULL check for dev in validate_linkmsg().

Note that we moved validate_linkmsg() check to the places where it has
not done any changes to the dev, as Jakub suggested.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/cf2ef061e08251faf9e8be25ff0d61150c030475.1686585334.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index d181512..2c61fb9 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2383,45 +2383,43 @@ static  int rtnl_set_vf_rate(struct net_device *dev, int vf, int min_tx_rate,
 static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[],
                            struct netlink_ext_ack *extack)
 {
-       if (dev) {
-               if (tb[IFLA_ADDRESS] &&
-                   nla_len(tb[IFLA_ADDRESS]) < dev->addr_len)
-                       return -EINVAL;
+       if (tb[IFLA_ADDRESS] &&
+           nla_len(tb[IFLA_ADDRESS]) < dev->addr_len)
+               return -EINVAL;
 
-               if (tb[IFLA_BROADCAST] &&
-                   nla_len(tb[IFLA_BROADCAST]) < dev->addr_len)
-                       return -EINVAL;
+       if (tb[IFLA_BROADCAST] &&
+           nla_len(tb[IFLA_BROADCAST]) < dev->addr_len)
+               return -EINVAL;
 
-               if (tb[IFLA_GSO_MAX_SIZE] &&
-                   nla_get_u32(tb[IFLA_GSO_MAX_SIZE]) > dev->tso_max_size) {
-                       NL_SET_ERR_MSG(extack, "too big gso_max_size");
-                       return -EINVAL;
-               }
+       if (tb[IFLA_GSO_MAX_SIZE] &&
+           nla_get_u32(tb[IFLA_GSO_MAX_SIZE]) > dev->tso_max_size) {
+               NL_SET_ERR_MSG(extack, "too big gso_max_size");
+               return -EINVAL;
+       }
 
-               if (tb[IFLA_GSO_MAX_SEGS] &&
-                   (nla_get_u32(tb[IFLA_GSO_MAX_SEGS]) > GSO_MAX_SEGS ||
-                    nla_get_u32(tb[IFLA_GSO_MAX_SEGS]) > dev->tso_max_segs)) {
-                       NL_SET_ERR_MSG(extack, "too big gso_max_segs");
-                       return -EINVAL;
-               }
+       if (tb[IFLA_GSO_MAX_SEGS] &&
+           (nla_get_u32(tb[IFLA_GSO_MAX_SEGS]) > GSO_MAX_SEGS ||
+            nla_get_u32(tb[IFLA_GSO_MAX_SEGS]) > dev->tso_max_segs)) {
+               NL_SET_ERR_MSG(extack, "too big gso_max_segs");
+               return -EINVAL;
+       }
 
-               if (tb[IFLA_GRO_MAX_SIZE] &&
-                   nla_get_u32(tb[IFLA_GRO_MAX_SIZE]) > GRO_MAX_SIZE) {
-                       NL_SET_ERR_MSG(extack, "too big gro_max_size");
-                       return -EINVAL;
-               }
+       if (tb[IFLA_GRO_MAX_SIZE] &&
+           nla_get_u32(tb[IFLA_GRO_MAX_SIZE]) > GRO_MAX_SIZE) {
+               NL_SET_ERR_MSG(extack, "too big gro_max_size");
+               return -EINVAL;
+       }
 
-               if (tb[IFLA_GSO_IPV4_MAX_SIZE] &&
-                   nla_get_u32(tb[IFLA_GSO_IPV4_MAX_SIZE]) > dev->tso_max_size) {
-                       NL_SET_ERR_MSG(extack, "too big gso_ipv4_max_size");
-                       return -EINVAL;
-               }
+       if (tb[IFLA_GSO_IPV4_MAX_SIZE] &&
+           nla_get_u32(tb[IFLA_GSO_IPV4_MAX_SIZE]) > dev->tso_max_size) {
+               NL_SET_ERR_MSG(extack, "too big gso_ipv4_max_size");
+               return -EINVAL;
+       }
 
-               if (tb[IFLA_GRO_IPV4_MAX_SIZE] &&
-                   nla_get_u32(tb[IFLA_GRO_IPV4_MAX_SIZE]) > GRO_MAX_SIZE) {
-                       NL_SET_ERR_MSG(extack, "too big gro_ipv4_max_size");
-                       return -EINVAL;
-               }
+       if (tb[IFLA_GRO_IPV4_MAX_SIZE] &&
+           nla_get_u32(tb[IFLA_GRO_IPV4_MAX_SIZE]) > GRO_MAX_SIZE) {
+               NL_SET_ERR_MSG(extack, "too big gro_ipv4_max_size");
+               return -EINVAL;
        }
 
        if (tb[IFLA_AF_SPEC]) {
@@ -2742,10 +2740,6 @@ static int do_setlink(const struct sk_buff *skb,
        char ifname[IFNAMSIZ];
        int err;
 
-       err = validate_linkmsg(dev, tb, extack);
-       if (err < 0)
-               return err;
-
        if (tb[IFLA_IFNAME])
                nla_strscpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
        else
@@ -3162,6 +3156,10 @@ static int rtnl_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
                goto errout;
        }
 
+       err = validate_linkmsg(dev, tb, extack);
+       if (err < 0)
+               goto errout;
+
        err = do_setlink(skb, dev, ifm, extack, tb, 0);
 errout:
        return err;
@@ -3405,6 +3403,9 @@ static int rtnl_group_changelink(const struct sk_buff *skb,
 
        for_each_netdev_safe(net, dev, aux) {
                if (dev->group == group) {
+                       err = validate_linkmsg(dev, tb, extack);
+                       if (err < 0)
+                               return err;
                        err = do_setlink(skb, dev, ifm, extack, tb, 0);
                        if (err < 0)
                                return err;
@@ -3562,10 +3563,6 @@ replay:
                        m_ops = master_dev->rtnl_link_ops;
        }
 
-       err = validate_linkmsg(dev, tb, extack);
-       if (err < 0)
-               return err;
-
        if (tb[IFLA_LINKINFO]) {
                err = nla_parse_nested_deprecated(linkinfo, IFLA_INFO_MAX,
                                                  tb[IFLA_LINKINFO],
@@ -3629,6 +3626,10 @@ replay:
                if (nlh->nlmsg_flags & NLM_F_REPLACE)
                        return -EOPNOTSUPP;
 
+               err = validate_linkmsg(dev, tb, extack);
+               if (err < 0)
+                       return err;
+
                if (linkinfo[IFLA_INFO_DATA]) {
                        if (!ops || ops != dev->rtnl_link_ops ||
                            !ops->changelink)