ipv4/metrics.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/netlink.h>
   3 #include <linux/nospec.h>
   4 #include <linux/rtnetlink.h>
   5 #include <linux/types.h>
   6 #include <net/ip.h>
   7 #include <net/net_namespace.h>
   8 #include <net/tcp.h>
   9
  10 static int ip_metrics_convert(struct net *net, struct nlattr *fc_mx,
  11                               int fc_mx_len, u32 *metrics,
  12                               struct netlink_ext_ack *extack)
  13 {
  14         bool ecn_ca = false;
  15         struct nlattr *nla;
  16         int remaining;
  17
  18         if (!fc_mx)
  19                 return 0;
  20
  21         nla_for_each_attr(nla, fc_mx, fc_mx_len, remaining) {
  22                 int type = nla_type(nla);
  23                 u32 val;
  24
  25                 if (!type)
  26                         continue;
  27                 if (type > RTAX_MAX) {
  28                         NL_SET_ERR_MSG(extack, "Invalid metric type");
  29                         return -EINVAL;
  30                 }
  31
  32                 type = array_index_nospec(type, RTAX_MAX + 1);
  33                 if (type == RTAX_CC_ALGO) {
  34                         char tmp[TCP_CA_NAME_MAX];
  35
  36                         nla_strscpy(tmp, nla, sizeof(tmp));
  37                         val = tcp_ca_get_key_by_name(net, tmp, &ecn_ca);
  38                         if (val == TCP_CA_UNSPEC) {
  39                                 NL_SET_ERR_MSG(extack, "Unknown tcp congestion algorithm");
  40                                 return -EINVAL;
  41                         }
  42                 } else {
  43                         if (nla_len(nla) != sizeof(u32)) {
  44                                 NL_SET_ERR_MSG_ATTR(extack, nla,
  45                                                     "Invalid attribute in metrics");
  46                                 return -EINVAL;
  47                         }
  48                         val = nla_get_u32(nla);
  49                 }
  50                 if (type == RTAX_ADVMSS && val > 65535 - 40)
  51                         val = 65535 - 40;
  52                 if (type == RTAX_MTU && val > 65535 - 15)
  53                         val = 65535 - 15;
  54                 if (type == RTAX_HOPLIMIT && val > 255)
  55                         val = 255;
  56                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK)) {
  57                         NL_SET_ERR_MSG(extack, "Unknown flag set in feature mask in metrics attribute");
  58                         return -EINVAL;
  59                 }
  60                 metrics[type - 1] = val;
  61         }
  62
  63         if (ecn_ca)
  64                 metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
  65
  66         return 0;
  67 }
  68
  69 struct dst_metrics *ip_fib_metrics_init(struct net *net, struct nlattr *fc_mx,
  70                                         int fc_mx_len,
  71                                         struct netlink_ext_ack *extack)
  72 {
  73         struct dst_metrics *fib_metrics;
  74         int err;
  75
  76         if (!fc_mx)
  77                 return (struct dst_metrics *)&dst_default_metrics;
  78
  79         fib_metrics = kzalloc(sizeof(*fib_metrics), GFP_KERNEL);
  80         if (unlikely(!fib_metrics))
  81                 return ERR_PTR(-ENOMEM);
  82
  83         err = ip_metrics_convert(net, fc_mx, fc_mx_len, fib_metrics->metrics,
  84                                  extack);
  85         if (!err) {
  86                 refcount_set(&fib_metrics->refcnt, 1);
  87         } else {
  88                 kfree(fib_metrics);
  89                 fib_metrics = ERR_PTR(err);
  90         }
  91
  92         return fib_metrics;
  93 }
  94 EXPORT_SYMBOL_GPL(ip_fib_metrics_init);