net: fib6: convert cfg metric to u32 outside of table write lock

Do the nla validation earlier, outside the write lock.

This is needed by followup patch which needs to be able to call
request_module (which can sleep) if needed.

Joint work with Daniel Borkmann.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 36 insertions, 33 deletions

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index db4984e13f2f..03c520a4ebeb 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -630,31 +630,35 @@ static bool rt6_qualify_for_ecmp(struct rt6_info *rt)
                RTF_GATEWAY;
 }
 
-static int fib6_commit_metrics(struct dst_entry *dst,
-                               struct nlattr *mx, int mx_len)
+static void fib6_copy_metrics(u32 *mp, const struct mx6_config *mxc)
 {
-        bool dst_host = dst->flags & DST_HOST;
-        struct nlattr *nla;
-        int remaining;
-        u32 *mp;
+        int i;
 
-        mp = dst_host ? dst_metrics_write_ptr(dst) :
-                        kzalloc(sizeof(u32) * RTAX_MAX, GFP_ATOMIC);
-        if (unlikely(!mp))
-                return -ENOMEM;
-        if (!dst_host)
-                dst_init_metrics(dst, mp, 0);
+        for (i = 0; i < RTAX_MAX; i++) {
+                if (test_bit(i, mxc->mx_valid))
+                        mp[i] = mxc->mx[i];
+        }
+}
+
+static int fib6_commit_metrics(struct dst_entry *dst, struct mx6_config *mxc)
+{
+        if (!mxc->mx)
+                return 0;
 
-        nla_for_each_attr(nla, mx, mx_len, remaining) {
-                int type = nla_type(nla);
+        if (dst->flags & DST_HOST) {
+                u32 *mp = dst_metrics_write_ptr(dst);
 
-                if (type) {
-                        if (type > RTAX_MAX)
-                                return -EINVAL;
+                if (unlikely(!mp))
+                        return -ENOMEM;
 
-                        mp[type - 1] = nla_get_u32(nla);
-                }
+                fib6_copy_metrics(mp, mxc);
+        } else {
+                dst_init_metrics(dst, mxc->mx, false);
+
+                /* We've stolen mx now. */
+                mxc->mx = NULL;
         }
+
         return 0;
 }
 
@@ -663,7 +667,7 @@ static int fib6_commit_metrics(struct dst_entry *dst,
  */
 
 static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
-                            struct nl_info *info, struct nlattr *mx, int mx_len)
+                            struct nl_info *info, struct mx6_config *mxc)
 {
         struct rt6_info *iter = NULL;
         struct rt6_info **ins;
@@ -772,11 +776,10 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
                         pr_warn("NLM_F_CREATE should be set when creating new route\n");
 
 add:
-                if (mx) {
-                        err = fib6_commit_metrics(&rt->dst, mx, mx_len);
-                        if (err)
-                                return err;
-                }
+                err = fib6_commit_metrics(&rt->dst, mxc);
+                if (err)
+                        return err;
+
                 rt->dst.rt6_next = iter;
                 *ins = rt;
                 rt->rt6i_node = fn;
@@ -796,11 +799,11 @@ add:
                         pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
                         return -ENOENT;
                 }
-                if (mx) {
-                        err = fib6_commit_metrics(&rt->dst, mx, mx_len);
-                        if (err)
-                                return err;
-                }
+
+                err = fib6_commit_metrics(&rt->dst, mxc);
+                if (err)
+                        return err;
+
                 *ins = rt;
                 rt->rt6i_node = fn;
                 rt->dst.rt6_next = iter->dst.rt6_next;
@@ -837,8 +840,8 @@ void fib6_force_start_gc(struct net *net)
  *      with source addr info in sub-trees
  */
 
-int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info,
-             struct nlattr *mx, int mx_len)
+int fib6_add(struct fib6_node *root, struct rt6_info *rt,
+             struct nl_info *info, struct mx6_config *mxc)
 {
         struct fib6_node *fn, *pn = NULL;
         int err = -ENOMEM;
@@ -933,7 +936,7 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info,
         }
 #endif
 
-        err = fib6_add_rt2node(fn, rt, info, mx, mx_len);
+        err = fib6_add_rt2node(fn, rt, info, mxc);
         if (!err) {
                 fib6_start_gc(info->nl_net, rt);
                 if (!(rt->rt6i_flags & RTF_CACHE))