net/ipv6/ioam6_iptunnel.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  IPv6 IOAM Lightweight Tunnel implementation
   4  *
   5  *  Author:
   6  *  Justin Iurman <justin.iurman@uliege.be>
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/skbuff.h>
  11 #include <linux/net.h>
  12 #include <linux/netlink.h>
  13 #include <linux/in6.h>
  14 #include <linux/ioam6.h>
  15 #include <linux/ioam6_iptunnel.h>
  16 #include <net/dst.h>
  17 #include <net/sock.h>
  18 #include <net/lwtunnel.h>
  19 #include <net/ioam6.h>
  20
  21 #define IOAM6_MASK_SHORT_FIELDS 0xff100000
  22 #define IOAM6_MASK_WIDE_FIELDS 0xe00000
  23
  24 struct ioam6_lwt_encap {
  25         struct ipv6_hopopt_hdr  eh;
  26         u8                      pad[2]; /* 2-octet padding for 4n-alignment */
  27         struct ioam6_hdr        ioamh;
  28         struct ioam6_trace_hdr  traceh;
  29 } __packed;
  30
  31 struct ioam6_lwt {
  32         struct ioam6_lwt_encap  tuninfo;
  33 };
  34
  35 static struct ioam6_lwt *ioam6_lwt_state(struct lwtunnel_state *lwt)
  36 {
  37         return (struct ioam6_lwt *)lwt->data;
  38 }
  39
  40 static struct ioam6_lwt_encap *ioam6_lwt_info(struct lwtunnel_state *lwt)
  41 {
  42         return &ioam6_lwt_state(lwt)->tuninfo;
  43 }
  44
  45 static struct ioam6_trace_hdr *ioam6_trace(struct lwtunnel_state *lwt)
  46 {
  47         return &(ioam6_lwt_state(lwt)->tuninfo.traceh);
  48 }
  49
  50 static const struct nla_policy ioam6_iptunnel_policy[IOAM6_IPTUNNEL_MAX + 1] = {
  51         [IOAM6_IPTUNNEL_TRACE]  = NLA_POLICY_EXACT_LEN(sizeof(struct ioam6_trace_hdr)),
  52 };
  53
  54 static int nla_put_ioam6_trace(struct sk_buff *skb, int attrtype,
  55                                struct ioam6_trace_hdr *trace)
  56 {
  57         struct ioam6_trace_hdr *data;
  58         struct nlattr *nla;
  59         int len;
  60
  61         len = sizeof(*trace);
  62
  63         nla = nla_reserve(skb, attrtype, len);
  64         if (!nla)
  65                 return -EMSGSIZE;
  66
  67         data = nla_data(nla);
  68         memcpy(data, trace, len);
  69
  70         return 0;
  71 }
  72
  73 static bool ioam6_validate_trace_hdr(struct ioam6_trace_hdr *trace)
  74 {
  75         u32 fields;
  76
  77         if (!trace->type_be32 || !trace->remlen ||
  78             trace->remlen > IOAM6_TRACE_DATA_SIZE_MAX / 4)
  79                 return false;
  80
  81         trace->nodelen = 0;
  82         fields = be32_to_cpu(trace->type_be32);
  83
  84         trace->nodelen += hweight32(fields & IOAM6_MASK_SHORT_FIELDS)
  85                                 * (sizeof(__be32) / 4);
  86         trace->nodelen += hweight32(fields & IOAM6_MASK_WIDE_FIELDS)
  87                                 * (sizeof(__be64) / 4);
  88
  89         return true;
  90 }
  91
  92 static int ioam6_build_state(struct net *net, struct nlattr *nla,
  93                              unsigned int family, const void *cfg,
  94                              struct lwtunnel_state **ts,
  95                              struct netlink_ext_ack *extack)
  96 {
  97         struct nlattr *tb[IOAM6_IPTUNNEL_MAX + 1];
  98         struct ioam6_lwt_encap *tuninfo;
  99         struct ioam6_trace_hdr *trace;
 100         struct lwtunnel_state *s;
 101         int len_aligned;
 102         int len, err;
 103
 104         if (family != AF_INET6)
 105                 return -EINVAL;
 106
 107         err = nla_parse_nested(tb, IOAM6_IPTUNNEL_MAX, nla,
 108                                ioam6_iptunnel_policy, extack);
 109         if (err < 0)
 110                 return err;
 111
 112         if (!tb[IOAM6_IPTUNNEL_TRACE]) {
 113                 NL_SET_ERR_MSG(extack, "missing trace");
 114                 return -EINVAL;
 115         }
 116
 117         trace = nla_data(tb[IOAM6_IPTUNNEL_TRACE]);
 118         if (!ioam6_validate_trace_hdr(trace)) {
 119                 NL_SET_ERR_MSG_ATTR(extack, tb[IOAM6_IPTUNNEL_TRACE],
 120                                     "invalid trace validation");
 121                 return -EINVAL;
 122         }
 123
 124         len = sizeof(*tuninfo) + trace->remlen * 4;
 125         len_aligned = ALIGN(len, 8);
 126
 127         s = lwtunnel_state_alloc(len_aligned);
 128         if (!s)
 129                 return -ENOMEM;
 130
 131         tuninfo = ioam6_lwt_info(s);
 132         tuninfo->eh.hdrlen = (len_aligned >> 3) - 1;
 133         tuninfo->pad[0] = IPV6_TLV_PADN;
 134         tuninfo->ioamh.type = IOAM6_TYPE_PREALLOC;
 135         tuninfo->ioamh.opt_type = IPV6_TLV_IOAM;
 136         tuninfo->ioamh.opt_len = sizeof(tuninfo->ioamh) - 2 + sizeof(*trace)
 137                                         + trace->remlen * 4;
 138
 139         memcpy(&tuninfo->traceh, trace, sizeof(*trace));
 140
 141         len = len_aligned - len;
 142         if (len == 1) {
 143                 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PAD1;
 144         } else if (len > 0) {
 145                 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PADN;
 146                 tuninfo->traceh.data[trace->remlen * 4 + 1] = len - 2;
 147         }
 148
 149         s->type = LWTUNNEL_ENCAP_IOAM6;
 150         s->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
 151
 152         *ts = s;
 153
 154         return 0;
 155 }
 156
 157 static int ioam6_do_inline(struct sk_buff *skb, struct ioam6_lwt_encap *tuninfo)
 158 {
 159         struct ioam6_trace_hdr *trace;
 160         struct ipv6hdr *oldhdr, *hdr;
 161         struct ioam6_namespace *ns;
 162         int hdrlen, err;
 163
 164         hdrlen = (tuninfo->eh.hdrlen + 1) << 3;
 165
 166         err = skb_cow_head(skb, hdrlen + skb->mac_len);
 167         if (unlikely(err))
 168                 return err;
 169
 170         oldhdr = ipv6_hdr(skb);
 171         skb_pull(skb, sizeof(*oldhdr));
 172         skb_postpull_rcsum(skb, skb_network_header(skb), sizeof(*oldhdr));
 173
 174         skb_push(skb, sizeof(*oldhdr) + hdrlen);
 175         skb_reset_network_header(skb);
 176         skb_mac_header_rebuild(skb);
 177
 178         hdr = ipv6_hdr(skb);
 179         memmove(hdr, oldhdr, sizeof(*oldhdr));
 180         tuninfo->eh.nexthdr = hdr->nexthdr;
 181
 182         skb_set_transport_header(skb, sizeof(*hdr));
 183         skb_postpush_rcsum(skb, hdr, sizeof(*hdr) + hdrlen);
 184
 185         memcpy(skb_transport_header(skb), (u8 *)tuninfo, hdrlen);
 186
 187         hdr->nexthdr = NEXTHDR_HOP;
 188         hdr->payload_len = cpu_to_be16(skb->len - sizeof(*hdr));
 189
 190         trace = (struct ioam6_trace_hdr *)(skb_transport_header(skb)
 191                                            + sizeof(struct ipv6_hopopt_hdr) + 2
 192                                            + sizeof(struct ioam6_hdr));
 193
 194         ns = ioam6_namespace(dev_net(skb_dst(skb)->dev), trace->namespace_id);
 195         if (ns)
 196                 ioam6_fill_trace_data(skb, ns, trace);
 197
 198         return 0;
 199 }
 200
 201 static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 202 {
 203         struct lwtunnel_state *lwt = skb_dst(skb)->lwtstate;
 204         int err = -EINVAL;
 205
 206         if (skb->protocol != htons(ETH_P_IPV6))
 207                 goto drop;
 208
 209         /* Only for packets we send and
 210          * that do not contain a Hop-by-Hop yet
 211          */
 212         if (skb->dev || ipv6_hdr(skb)->nexthdr == NEXTHDR_HOP)
 213                 goto out;
 214
 215         err = ioam6_do_inline(skb, ioam6_lwt_info(lwt));
 216         if (unlikely(err))
 217                 goto drop;
 218
 219         err = skb_cow_head(skb, LL_RESERVED_SPACE(skb_dst(skb)->dev));
 220         if (unlikely(err))
 221                 goto drop;
 222
 223 out:
 224         return lwt->orig_output(net, sk, skb);
 225
 226 drop:
 227         kfree_skb(skb);
 228         return err;
 229 }
 230
 231 static int ioam6_fill_encap_info(struct sk_buff *skb,
 232                                  struct lwtunnel_state *lwtstate)
 233 {
 234         struct ioam6_trace_hdr *trace = ioam6_trace(lwtstate);
 235
 236         if (nla_put_ioam6_trace(skb, IOAM6_IPTUNNEL_TRACE, trace))
 237                 return -EMSGSIZE;
 238
 239         return 0;
 240 }
 241
 242 static int ioam6_encap_nlsize(struct lwtunnel_state *lwtstate)
 243 {
 244         struct ioam6_trace_hdr *trace = ioam6_trace(lwtstate);
 245
 246         return nla_total_size(sizeof(*trace));
 247 }
 248
 249 static int ioam6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
 250 {
 251         struct ioam6_trace_hdr *a_hdr = ioam6_trace(a);
 252         struct ioam6_trace_hdr *b_hdr = ioam6_trace(b);
 253
 254         return (a_hdr->namespace_id != b_hdr->namespace_id);
 255 }
 256
 257 static const struct lwtunnel_encap_ops ioam6_iptun_ops = {
 258         .build_state    = ioam6_build_state,
 259         .output         = ioam6_output,
 260         .fill_encap     = ioam6_fill_encap_info,
 261         .get_encap_size = ioam6_encap_nlsize,
 262         .cmp_encap      = ioam6_encap_cmp,
 263         .owner          = THIS_MODULE,
 264 };
 265
 266 int __init ioam6_iptunnel_init(void)
 267 {
 268         return lwtunnel_encap_add_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
 269 }
 270
 271 void ioam6_iptunnel_exit(void)
 272 {
 273         lwtunnel_encap_del_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
 274 }