net/ipv4/metrics.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/netlink.h>
   3 #include <linux/rtnetlink.h>
   4 #include <linux/types.h>
   5 #include <net/ip.h>
   6 #include <net/net_namespace.h>
   7 #include <net/tcp.h>
   8
   9 static int ip_metrics_convert(struct net *net, struct nlattr *fc_mx,
  10                               int fc_mx_len, u32 *metrics,
  11                               struct netlink_ext_ack *extack)
  12 {
  13         bool ecn_ca = false;
  14         struct nlattr *nla;
  15         int remaining;
  16
  17         nla_for_each_attr(nla, fc_mx, fc_mx_len, remaining) {
  18                 int type = nla_type(nla);
  19                 u32 val;
  20
  21                 if (!type)
  22                         continue;
  23                 if (type > RTAX_MAX) {
  24                         NL_SET_ERR_MSG(extack, "Invalid metric type");
  25                         return -EINVAL;
  26                 }
  27
  28                 if (type == RTAX_CC_ALGO) {
  29                         char tmp[TCP_CA_NAME_MAX];
  30
  31                         nla_strscpy(tmp, nla, sizeof(tmp));
  32                         val = tcp_ca_get_key_by_name(net, tmp, &ecn_ca);
  33                         if (val == TCP_CA_UNSPEC) {
  34                                 NL_SET_ERR_MSG(extack, "Unknown tcp congestion algorithm");
  35                                 return -EINVAL;
  36                         }
  37                 } else {
  38                         if (nla_len(nla) != sizeof(u32)) {
  39                                 NL_SET_ERR_MSG_ATTR(extack, nla,
  40                                                     "Invalid attribute in metrics");
  41                                 return -EINVAL;
  42                         }
  43                         val = nla_get_u32(nla);
  44                 }
  45                 if (type == RTAX_ADVMSS && val > 65535 - 40)
  46                         val = 65535 - 40;
  47                 if (type == RTAX_MTU && val > 65535 - 15)
  48                         val = 65535 - 15;
  49                 if (type == RTAX_HOPLIMIT && val > 255)
  50                         val = 255;
  51                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK)) {
  52                         NL_SET_ERR_MSG(extack, "Unknown flag set in feature mask in metrics attribute");
  53                         return -EINVAL;
  54                 }
  55                 metrics[type - 1] = val;
  56         }
  57
  58         if (ecn_ca)
  59                 metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
  60
  61         return 0;
  62 }
  63
  64 struct dst_metrics *ip_fib_metrics_init(struct net *net, struct nlattr *fc_mx,
  65                                         int fc_mx_len,
  66                                         struct netlink_ext_ack *extack)
  67 {
  68         struct dst_metrics *fib_metrics;
  69         int err;
  70
  71         if (!fc_mx)
  72                 return (struct dst_metrics *)&dst_default_metrics;
  73
  74         fib_metrics = kzalloc(sizeof(*fib_metrics), GFP_KERNEL);
  75         if (unlikely(!fib_metrics))
  76                 return ERR_PTR(-ENOMEM);
  77
  78         err = ip_metrics_convert(net, fc_mx, fc_mx_len, fib_metrics->metrics,
  79                                  extack);
  80         if (!err) {
  81                 refcount_set(&fib_metrics->refcnt, 1);
  82         } else {
  83                 kfree(fib_metrics);
  84                 fib_metrics = ERR_PTR(err);
  85         }
  86
  87         return fib_metrics;
  88 }
  89 EXPORT_SYMBOL_GPL(ip_fib_metrics_init);