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