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             trace->type.bit12 | trace->type.bit13 | trace->type.bit14 |
  80             trace->type.bit15 | trace->type.bit16 | trace->type.bit17 |
  81             trace->type.bit18 | trace->type.bit19 | trace->type.bit20 |
  82             trace->type.bit21)
  83                 return false;
  84
  85         trace->nodelen = 0;
  86         fields = be32_to_cpu(trace->type_be32);
  87
  88         trace->nodelen += hweight32(fields & IOAM6_MASK_SHORT_FIELDS)
  89                                 * (sizeof(__be32) / 4);
  90         trace->nodelen += hweight32(fields & IOAM6_MASK_WIDE_FIELDS)
  91                                 * (sizeof(__be64) / 4);
  92
  93         return true;
  94 }
  95
  96 static int ioam6_build_state(struct net *net, struct nlattr *nla,
  97                              unsigned int family, const void *cfg,
  98                              struct lwtunnel_state **ts,
  99                              struct netlink_ext_ack *extack)
 100 {
 101         struct nlattr *tb[IOAM6_IPTUNNEL_MAX + 1];
 102         struct ioam6_lwt_encap *tuninfo;
 103         struct ioam6_trace_hdr *trace;
 104         struct lwtunnel_state *s;
 105         int len_aligned;
 106         int len, err;
 107
 108         if (family != AF_INET6)
 109                 return -EINVAL;
 110
 111         err = nla_parse_nested(tb, IOAM6_IPTUNNEL_MAX, nla,
 112                                ioam6_iptunnel_policy, extack);
 113         if (err < 0)
 114                 return err;
 115
 116         if (!tb[IOAM6_IPTUNNEL_TRACE]) {
 117                 NL_SET_ERR_MSG(extack, "missing trace");
 118                 return -EINVAL;
 119         }
 120
 121         trace = nla_data(tb[IOAM6_IPTUNNEL_TRACE]);
 122         if (!ioam6_validate_trace_hdr(trace)) {
 123                 NL_SET_ERR_MSG_ATTR(extack, tb[IOAM6_IPTUNNEL_TRACE],
 124                                     "invalid trace validation");
 125                 return -EINVAL;
 126         }
 127
 128         len = sizeof(*tuninfo) + trace->remlen * 4;
 129         len_aligned = ALIGN(len, 8);
 130
 131         s = lwtunnel_state_alloc(len_aligned);
 132         if (!s)
 133                 return -ENOMEM;
 134
 135         tuninfo = ioam6_lwt_info(s);
 136         tuninfo->eh.hdrlen = (len_aligned >> 3) - 1;
 137         tuninfo->pad[0] = IPV6_TLV_PADN;
 138         tuninfo->ioamh.type = IOAM6_TYPE_PREALLOC;
 139         tuninfo->ioamh.opt_type = IPV6_TLV_IOAM;
 140         tuninfo->ioamh.opt_len = sizeof(tuninfo->ioamh) - 2 + sizeof(*trace)
 141                                         + trace->remlen * 4;
 142
 143         memcpy(&tuninfo->traceh, trace, sizeof(*trace));
 144
 145         len = len_aligned - len;
 146         if (len == 1) {
 147                 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PAD1;
 148         } else if (len > 0) {
 149                 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PADN;
 150                 tuninfo->traceh.data[trace->remlen * 4 + 1] = len - 2;
 151         }
 152
 153         s->type = LWTUNNEL_ENCAP_IOAM6;
 154         s->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
 155
 156         *ts = s;
 157
 158         return 0;
 159 }
 160
 161 static int ioam6_do_inline(struct sk_buff *skb, struct ioam6_lwt_encap *tuninfo)
 162 {
 163         struct ioam6_trace_hdr *trace;
 164         struct ipv6hdr *oldhdr, *hdr;
 165         struct ioam6_namespace *ns;
 166         int hdrlen, err;
 167
 168         hdrlen = (tuninfo->eh.hdrlen + 1) << 3;
 169
 170         err = skb_cow_head(skb, hdrlen + skb->mac_len);
 171         if (unlikely(err))
 172                 return err;
 173
 174         oldhdr = ipv6_hdr(skb);
 175         skb_pull(skb, sizeof(*oldhdr));
 176         skb_postpull_rcsum(skb, skb_network_header(skb), sizeof(*oldhdr));
 177
 178         skb_push(skb, sizeof(*oldhdr) + hdrlen);
 179         skb_reset_network_header(skb);
 180         skb_mac_header_rebuild(skb);
 181
 182         hdr = ipv6_hdr(skb);
 183         memmove(hdr, oldhdr, sizeof(*oldhdr));
 184         tuninfo->eh.nexthdr = hdr->nexthdr;
 185
 186         skb_set_transport_header(skb, sizeof(*hdr));
 187         skb_postpush_rcsum(skb, hdr, sizeof(*hdr) + hdrlen);
 188
 189         memcpy(skb_transport_header(skb), (u8 *)tuninfo, hdrlen);
 190
 191         hdr->nexthdr = NEXTHDR_HOP;
 192         hdr->payload_len = cpu_to_be16(skb->len - sizeof(*hdr));
 193
 194         trace = (struct ioam6_trace_hdr *)(skb_transport_header(skb)
 195                                            + sizeof(struct ipv6_hopopt_hdr) + 2
 196                                            + sizeof(struct ioam6_hdr));
 197
 198         ns = ioam6_namespace(dev_net(skb_dst(skb)->dev), trace->namespace_id);
 199         if (ns)
 200                 ioam6_fill_trace_data(skb, ns, trace);
 201
 202         return 0;
 203 }
 204
 205 static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 206 {
 207         struct lwtunnel_state *lwt = skb_dst(skb)->lwtstate;
 208         int err = -EINVAL;
 209
 210         if (skb->protocol != htons(ETH_P_IPV6))
 211                 goto drop;
 212
 213         /* Only for packets we send and
 214          * that do not contain a Hop-by-Hop yet
 215          */
 216         if (skb->dev || ipv6_hdr(skb)->nexthdr == NEXTHDR_HOP)
 217                 goto out;
 218
 219         err = ioam6_do_inline(skb, ioam6_lwt_info(lwt));
 220         if (unlikely(err))
 221                 goto drop;
 222
 223         err = skb_cow_head(skb, LL_RESERVED_SPACE(skb_dst(skb)->dev));
 224         if (unlikely(err))
 225                 goto drop;
 226
 227 out:
 228         return lwt->orig_output(net, sk, skb);
 229
 230 drop:
 231         kfree_skb(skb);
 232         return err;
 233 }
 234
 235 static int ioam6_fill_encap_info(struct sk_buff *skb,
 236                                  struct lwtunnel_state *lwtstate)
 237 {
 238         struct ioam6_trace_hdr *trace = ioam6_trace(lwtstate);
 239
 240         if (nla_put_ioam6_trace(skb, IOAM6_IPTUNNEL_TRACE, trace))
 241                 return -EMSGSIZE;
 242
 243         return 0;
 244 }
 245
 246 static int ioam6_encap_nlsize(struct lwtunnel_state *lwtstate)
 247 {
 248         struct ioam6_trace_hdr *trace = ioam6_trace(lwtstate);
 249
 250         return nla_total_size(sizeof(*trace));
 251 }
 252
 253 static int ioam6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
 254 {
 255         struct ioam6_trace_hdr *a_hdr = ioam6_trace(a);
 256         struct ioam6_trace_hdr *b_hdr = ioam6_trace(b);
 257
 258         return (a_hdr->namespace_id != b_hdr->namespace_id);
 259 }
 260
 261 static const struct lwtunnel_encap_ops ioam6_iptun_ops = {
 262         .build_state    = ioam6_build_state,
 263         .output         = ioam6_output,
 264         .fill_encap     = ioam6_fill_encap_info,
 265         .get_encap_size = ioam6_encap_nlsize,
 266         .cmp_encap      = ioam6_encap_cmp,
 267         .owner          = THIS_MODULE,
 268 };
 269
 270 int __init ioam6_iptunnel_init(void)
 271 {
 272         return lwtunnel_encap_add_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
 273 }
 274
 275 void ioam6_iptunnel_exit(void)
 276 {
 277         lwtunnel_encap_del_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
 278 }