drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2013-2018, 2021, The Linux Foundation. All rights reserved.
   3  *
   4  * RMNET Data MAP protocol
   5  */
   6
   7 #include <linux/netdevice.h>
   8 #include <linux/ip.h>
   9 #include <linux/ipv6.h>
  10 #include <net/ip6_checksum.h>
  11 #include <linux/bitfield.h>
  12 #include "rmnet_config.h"
  13 #include "rmnet_map.h"
  14 #include "rmnet_private.h"
  15
  16 #define RMNET_MAP_DEAGGR_SPACING  64
  17 #define RMNET_MAP_DEAGGR_HEADROOM (RMNET_MAP_DEAGGR_SPACING / 2)
  18
  19 static __sum16 *rmnet_map_get_csum_field(unsigned char protocol,
  20                                          const void *txporthdr)
  21 {
  22         if (protocol == IPPROTO_TCP)
  23                 return &((struct tcphdr *)txporthdr)->check;
  24
  25         if (protocol == IPPROTO_UDP)
  26                 return &((struct udphdr *)txporthdr)->check;
  27
  28         return NULL;
  29 }
  30
  31 static int
  32 rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb,
  33                                struct rmnet_map_dl_csum_trailer *csum_trailer,
  34                                struct rmnet_priv *priv)
  35 {
  36         struct iphdr *ip4h = (struct iphdr *)skb->data;
  37         void *txporthdr = skb->data + ip4h->ihl * 4;
  38         __sum16 *csum_field, pseudo_csum;
  39         __sum16 ip_payload_csum;
  40         __sum16 csum_value_final;
  41
  42         /* Computing the checksum over just the IPv4 header--including its
  43          * checksum field--should yield 0.  If it doesn't, the IP header
  44          * is bad, so return an error and let the IP layer drop it.
  45          */
  46         if (ip_fast_csum(ip4h, ip4h->ihl)) {
  47                 priv->stats.csum_ip4_header_bad++;
  48                 return -EINVAL;
  49         }
  50
  51         /* We don't support checksum offload on IPv4 fragments */
  52         if (ip_is_fragment(ip4h)) {
  53                 priv->stats.csum_fragmented_pkt++;
  54                 return -EOPNOTSUPP;
  55         }
  56
  57         /* Checksum offload is only supported for UDP and TCP protocols */
  58         csum_field = rmnet_map_get_csum_field(ip4h->protocol, txporthdr);
  59         if (!csum_field) {
  60                 priv->stats.csum_err_invalid_transport++;
  61                 return -EPROTONOSUPPORT;
  62         }
  63
  64         /* RFC 768: UDP checksum is optional for IPv4, and is 0 if unused */
  65         if (!*csum_field && ip4h->protocol == IPPROTO_UDP) {
  66                 priv->stats.csum_skipped++;
  67                 return 0;
  68         }
  69
  70         /* The checksum value in the trailer is computed over the entire
  71          * IP packet, including the IP header and payload.  To derive the
  72          * transport checksum from this, we first subract the contribution
  73          * of the IP header from the trailer checksum.  We then add the
  74          * checksum computed over the pseudo header.
  75          *
  76          * We verified above that the IP header contributes zero to the
  77          * trailer checksum.  Therefore the checksum in the trailer is
  78          * just the checksum computed over the IP payload.
  79          */
  80         ip_payload_csum = (__force __sum16)~csum_trailer->csum_value;
  81
  82         pseudo_csum = ~csum_tcpudp_magic(ip4h->saddr, ip4h->daddr,
  83                                          ntohs(ip4h->tot_len) - ip4h->ihl * 4,
  84                                          ip4h->protocol, 0);
  85         pseudo_csum = csum16_add(ip_payload_csum, (__force __be16)pseudo_csum);
  86
  87         csum_value_final = ~csum16_sub(pseudo_csum, (__force __be16)*csum_field);
  88
  89         if (unlikely(!csum_value_final)) {
  90                 switch (ip4h->protocol) {
  91                 case IPPROTO_UDP:
  92                         /* RFC 768 - DL4 1's complement rule for UDP csum 0 */
  93                         csum_value_final = ~csum_value_final;
  94                         break;
  95
  96                 case IPPROTO_TCP:
  97                         /* DL4 Non-RFC compliant TCP checksum found */
  98                         if (*csum_field == (__force __sum16)0xFFFF)
  99                                 csum_value_final = ~csum_value_final;
 100                         break;
 101                 }
 102         }
 103
 104         if (csum_value_final == *csum_field) {
 105                 priv->stats.csum_ok++;
 106                 return 0;
 107         } else {
 108                 priv->stats.csum_validation_failed++;
 109                 return -EINVAL;
 110         }
 111 }
 112
 113 #if IS_ENABLED(CONFIG_IPV6)
 114 static int
 115 rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
 116                                struct rmnet_map_dl_csum_trailer *csum_trailer,
 117                                struct rmnet_priv *priv)
 118 {
 119         struct ipv6hdr *ip6h = (struct ipv6hdr *)skb->data;
 120         void *txporthdr = skb->data + sizeof(*ip6h);
 121         __sum16 *csum_field, pseudo_csum;
 122         __sum16 ip6_payload_csum;
 123         __be16 ip_header_csum;
 124         __sum16 csum_value_final;
 125         u32 length;
 126
 127         /* Checksum offload is only supported for UDP and TCP protocols;
 128          * the packet cannot include any IPv6 extension headers
 129          */
 130         csum_field = rmnet_map_get_csum_field(ip6h->nexthdr, txporthdr);
 131         if (!csum_field) {
 132                 priv->stats.csum_err_invalid_transport++;
 133                 return -EPROTONOSUPPORT;
 134         }
 135
 136         /* The checksum value in the trailer is computed over the entire
 137          * IP packet, including the IP header and payload.  To derive the
 138          * transport checksum from this, we first subract the contribution
 139          * of the IP header from the trailer checksum.  We then add the
 140          * checksum computed over the pseudo header.
 141          */
 142         ip_header_csum = (__force __be16)ip_fast_csum(ip6h, sizeof(*ip6h) / 4);
 143         ip6_payload_csum = ~csum16_sub((__force __sum16)csum_trailer->csum_value,
 144                                        ip_header_csum);
 145
 146         length = (ip6h->nexthdr == IPPROTO_UDP) ?
 147                  ntohs(((struct udphdr *)txporthdr)->len) :
 148                  ntohs(ip6h->payload_len);
 149         pseudo_csum = ~csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 150                                        length, ip6h->nexthdr, 0);
 151         pseudo_csum = csum16_add(ip6_payload_csum, (__force __be16)pseudo_csum);
 152
 153         csum_value_final = ~csum16_sub(pseudo_csum, (__force __be16)*csum_field);
 154
 155         if (unlikely(csum_value_final == 0)) {
 156                 switch (ip6h->nexthdr) {
 157                 case IPPROTO_UDP:
 158                         /* RFC 2460 section 8.1
 159                          * DL6 One's complement rule for UDP checksum 0
 160                          */
 161                         csum_value_final = ~csum_value_final;
 162                         break;
 163
 164                 case IPPROTO_TCP:
 165                         /* DL6 Non-RFC compliant TCP checksum found */
 166                         if (*csum_field == (__force __sum16)0xFFFF)
 167                                 csum_value_final = ~csum_value_final;
 168                         break;
 169                 }
 170         }
 171
 172         if (csum_value_final == *csum_field) {
 173                 priv->stats.csum_ok++;
 174                 return 0;
 175         } else {
 176                 priv->stats.csum_validation_failed++;
 177                 return -EINVAL;
 178         }
 179 }
 180 #endif
 181
 182 static void rmnet_map_complement_ipv4_txporthdr_csum_field(void *iphdr)
 183 {
 184         struct iphdr *ip4h = (struct iphdr *)iphdr;
 185         void *txphdr;
 186         u16 *csum;
 187
 188         txphdr = iphdr + ip4h->ihl * 4;
 189
 190         if (ip4h->protocol == IPPROTO_TCP || ip4h->protocol == IPPROTO_UDP) {
 191                 csum = (u16 *)rmnet_map_get_csum_field(ip4h->protocol, txphdr);
 192                 *csum = ~(*csum);
 193         }
 194 }
 195
 196 static void
 197 rmnet_map_ipv4_ul_csum_header(struct iphdr *iphdr,
 198                               struct rmnet_map_ul_csum_header *ul_header,
 199                               struct sk_buff *skb)
 200 {
 201         u16 val;
 202
 203         val = MAP_CSUM_UL_ENABLED_FLAG;
 204         if (iphdr->protocol == IPPROTO_UDP)
 205                 val |= MAP_CSUM_UL_UDP_FLAG;
 206         val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK;
 207
 208         ul_header->csum_start_offset = htons(skb_network_header_len(skb));
 209         ul_header->csum_info = htons(val);
 210
 211         skb->ip_summed = CHECKSUM_NONE;
 212
 213         rmnet_map_complement_ipv4_txporthdr_csum_field(iphdr);
 214 }
 215
 216 #if IS_ENABLED(CONFIG_IPV6)
 217 static void rmnet_map_complement_ipv6_txporthdr_csum_field(void *ip6hdr)
 218 {
 219         struct ipv6hdr *ip6h = (struct ipv6hdr *)ip6hdr;
 220         void *txphdr;
 221         u16 *csum;
 222
 223         txphdr = ip6hdr + sizeof(struct ipv6hdr);
 224
 225         if (ip6h->nexthdr == IPPROTO_TCP || ip6h->nexthdr == IPPROTO_UDP) {
 226                 csum = (u16 *)rmnet_map_get_csum_field(ip6h->nexthdr, txphdr);
 227                 *csum = ~(*csum);
 228         }
 229 }
 230
 231 static void
 232 rmnet_map_ipv6_ul_csum_header(struct ipv6hdr *ipv6hdr,
 233                               struct rmnet_map_ul_csum_header *ul_header,
 234                               struct sk_buff *skb)
 235 {
 236         u16 val;
 237
 238         val = MAP_CSUM_UL_ENABLED_FLAG;
 239         if (ipv6hdr->nexthdr == IPPROTO_UDP)
 240                 val |= MAP_CSUM_UL_UDP_FLAG;
 241         val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK;
 242
 243         ul_header->csum_start_offset = htons(skb_network_header_len(skb));
 244         ul_header->csum_info = htons(val);
 245
 246         skb->ip_summed = CHECKSUM_NONE;
 247
 248         rmnet_map_complement_ipv6_txporthdr_csum_field(ipv6hdr);
 249 }
 250 #endif
 251
 252 static void rmnet_map_v5_checksum_uplink_packet(struct sk_buff *skb,
 253                                                 struct rmnet_port *port,
 254                                                 struct net_device *orig_dev)
 255 {
 256         struct rmnet_priv *priv = netdev_priv(orig_dev);
 257         struct rmnet_map_v5_csum_header *ul_header;
 258
 259         ul_header = skb_push(skb, sizeof(*ul_header));
 260         memset(ul_header, 0, sizeof(*ul_header));
 261         ul_header->header_info = u8_encode_bits(RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD,
 262                                                 MAPV5_HDRINFO_HDR_TYPE_FMASK);
 263
 264         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 265                 void *iph = ip_hdr(skb);
 266                 __sum16 *check;
 267                 void *trans;
 268                 u8 proto;
 269
 270                 if (skb->protocol == htons(ETH_P_IP)) {
 271                         u16 ip_len = ((struct iphdr *)iph)->ihl * 4;
 272
 273                         proto = ((struct iphdr *)iph)->protocol;
 274                         trans = iph + ip_len;
 275                 } else if (IS_ENABLED(CONFIG_IPV6) &&
 276                            skb->protocol == htons(ETH_P_IPV6)) {
 277                         u16 ip_len = sizeof(struct ipv6hdr);
 278
 279                         proto = ((struct ipv6hdr *)iph)->nexthdr;
 280                         trans = iph + ip_len;
 281                 } else {
 282                         priv->stats.csum_err_invalid_ip_version++;
 283                         goto sw_csum;
 284                 }
 285
 286                 check = rmnet_map_get_csum_field(proto, trans);
 287                 if (check) {
 288                         skb->ip_summed = CHECKSUM_NONE;
 289                         /* Ask for checksum offloading */
 290                         ul_header->csum_info |= MAPV5_CSUMINFO_VALID_FLAG;
 291                         priv->stats.csum_hw++;
 292                         return;
 293                 }
 294         }
 295
 296 sw_csum:
 297         priv->stats.csum_sw++;
 298 }
 299
 300 /* Adds MAP header to front of skb->data
 301  * Padding is calculated and set appropriately in MAP header. Mux ID is
 302  * initialized to 0.
 303  */
 304 struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb,
 305                                                   int hdrlen,
 306                                                   struct rmnet_port *port,
 307                                                   int pad)
 308 {
 309         struct rmnet_map_header *map_header;
 310         u32 padding, map_datalen;
 311         u8 *padbytes;
 312
 313         map_datalen = skb->len - hdrlen;
 314         map_header = (struct rmnet_map_header *)
 315                         skb_push(skb, sizeof(struct rmnet_map_header));
 316         memset(map_header, 0, sizeof(struct rmnet_map_header));
 317
 318         /* Set next_hdr bit for csum offload packets */
 319         if (port->data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5)
 320                 map_header->flags |= MAP_NEXT_HEADER_FLAG;
 321
 322         if (pad == RMNET_MAP_NO_PAD_BYTES) {
 323                 map_header->pkt_len = htons(map_datalen);
 324                 return map_header;
 325         }
 326
 327         BUILD_BUG_ON(MAP_PAD_LEN_MASK < 3);
 328         padding = ALIGN(map_datalen, 4) - map_datalen;
 329
 330         if (padding == 0)
 331                 goto done;
 332
 333         if (skb_tailroom(skb) < padding)
 334                 return NULL;
 335
 336         padbytes = (u8 *)skb_put(skb, padding);
 337         memset(padbytes, 0, padding);
 338
 339 done:
 340         map_header->pkt_len = htons(map_datalen + padding);
 341         /* This is a data packet, so the CMD bit is 0 */
 342         map_header->flags = padding & MAP_PAD_LEN_MASK;
 343
 344         return map_header;
 345 }
 346
 347 /* Deaggregates a single packet
 348  * A whole new buffer is allocated for each portion of an aggregated frame.
 349  * Caller should keep calling deaggregate() on the source skb until 0 is
 350  * returned, indicating that there are no more packets to deaggregate. Caller
 351  * is responsible for freeing the original skb.
 352  */
 353 struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
 354                                       struct rmnet_port *port)
 355 {
 356         struct rmnet_map_v5_csum_header *next_hdr = NULL;
 357         struct rmnet_map_header *maph;
 358         void *data = skb->data;
 359         struct sk_buff *skbn;
 360         u8 nexthdr_type;
 361         u32 packet_len;
 362
 363         if (skb->len == 0)
 364                 return NULL;
 365
 366         maph = (struct rmnet_map_header *)skb->data;
 367         packet_len = ntohs(maph->pkt_len) + sizeof(*maph);
 368
 369         if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) {
 370                 packet_len += sizeof(struct rmnet_map_dl_csum_trailer);
 371         } else if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) {
 372                 if (!(maph->flags & MAP_CMD_FLAG)) {
 373                         packet_len += sizeof(*next_hdr);
 374                         if (maph->flags & MAP_NEXT_HEADER_FLAG)
 375                                 next_hdr = data + sizeof(*maph);
 376                         else
 377                                 /* Mapv5 data pkt without csum hdr is invalid */
 378                                 return NULL;
 379                 }
 380         }
 381
 382         if (((int)skb->len - (int)packet_len) < 0)
 383                 return NULL;
 384
 385         /* Some hardware can send us empty frames. Catch them */
 386         if (!maph->pkt_len)
 387                 return NULL;
 388
 389         if (next_hdr) {
 390                 nexthdr_type = u8_get_bits(next_hdr->header_info,
 391                                            MAPV5_HDRINFO_HDR_TYPE_FMASK);
 392                 if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
 393                         return NULL;
 394         }
 395
 396         skbn = alloc_skb(packet_len + RMNET_MAP_DEAGGR_SPACING, GFP_ATOMIC);
 397         if (!skbn)
 398                 return NULL;
 399
 400         skb_reserve(skbn, RMNET_MAP_DEAGGR_HEADROOM);
 401         skb_put(skbn, packet_len);
 402         memcpy(skbn->data, skb->data, packet_len);
 403         skb_pull(skb, packet_len);
 404
 405         return skbn;
 406 }
 407
 408 /* Validates packet checksums. Function takes a pointer to
 409  * the beginning of a buffer which contains the IP payload +
 410  * padding + checksum trailer.
 411  * Only IPv4 and IPv6 are supported along with TCP & UDP.
 412  * Fragmented or tunneled packets are not supported.
 413  */
 414 int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len)
 415 {
 416         struct rmnet_priv *priv = netdev_priv(skb->dev);
 417         struct rmnet_map_dl_csum_trailer *csum_trailer;
 418
 419         if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
 420                 priv->stats.csum_sw++;
 421                 return -EOPNOTSUPP;
 422         }
 423
 424         csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len);
 425
 426         if (!(csum_trailer->flags & MAP_CSUM_DL_VALID_FLAG)) {
 427                 priv->stats.csum_valid_unset++;
 428                 return -EINVAL;
 429         }
 430
 431         if (skb->protocol == htons(ETH_P_IP))
 432                 return rmnet_map_ipv4_dl_csum_trailer(skb, csum_trailer, priv);
 433
 434         if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6))
 435                 return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer, priv);
 436
 437         priv->stats.csum_err_invalid_ip_version++;
 438
 439         return -EPROTONOSUPPORT;
 440 }
 441
 442 static void rmnet_map_v4_checksum_uplink_packet(struct sk_buff *skb,
 443                                                 struct net_device *orig_dev)
 444 {
 445         struct rmnet_priv *priv = netdev_priv(orig_dev);
 446         struct rmnet_map_ul_csum_header *ul_header;
 447         void *iphdr;
 448
 449         ul_header = (struct rmnet_map_ul_csum_header *)
 450                     skb_push(skb, sizeof(struct rmnet_map_ul_csum_header));
 451
 452         if (unlikely(!(orig_dev->features &
 453                      (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM))))
 454                 goto sw_csum;
 455
 456         if (skb->ip_summed != CHECKSUM_PARTIAL)
 457                 goto sw_csum;
 458
 459         iphdr = (char *)ul_header +
 460                 sizeof(struct rmnet_map_ul_csum_header);
 461
 462         if (skb->protocol == htons(ETH_P_IP)) {
 463                 rmnet_map_ipv4_ul_csum_header(iphdr, ul_header, skb);
 464                 priv->stats.csum_hw++;
 465                 return;
 466         }
 467
 468         if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) {
 469                 rmnet_map_ipv6_ul_csum_header(iphdr, ul_header, skb);
 470                 priv->stats.csum_hw++;
 471                 return;
 472         }
 473
 474         priv->stats.csum_err_invalid_ip_version++;
 475
 476 sw_csum:
 477         memset(ul_header, 0, sizeof(*ul_header));
 478
 479         priv->stats.csum_sw++;
 480 }
 481
 482 /* Generates UL checksum meta info header for IPv4 and IPv6 over TCP and UDP
 483  * packets that are supported for UL checksum offload.
 484  */
 485 void rmnet_map_checksum_uplink_packet(struct sk_buff *skb,
 486                                       struct rmnet_port *port,
 487                                       struct net_device *orig_dev,
 488                                       int csum_type)
 489 {
 490         switch (csum_type) {
 491         case RMNET_FLAGS_EGRESS_MAP_CKSUMV4:
 492                 rmnet_map_v4_checksum_uplink_packet(skb, orig_dev);
 493                 break;
 494         case RMNET_FLAGS_EGRESS_MAP_CKSUMV5:
 495                 rmnet_map_v5_checksum_uplink_packet(skb, port, orig_dev);
 496                 break;
 497         default:
 498                 break;
 499         }
 500 }
 501
 502 /* Process a MAPv5 packet header */
 503 int rmnet_map_process_next_hdr_packet(struct sk_buff *skb,
 504                                       u16 len)
 505 {
 506         struct rmnet_priv *priv = netdev_priv(skb->dev);
 507         struct rmnet_map_v5_csum_header *next_hdr;
 508         u8 nexthdr_type;
 509
 510         next_hdr = (struct rmnet_map_v5_csum_header *)(skb->data +
 511                         sizeof(struct rmnet_map_header));
 512
 513         nexthdr_type = u8_get_bits(next_hdr->header_info,
 514                                    MAPV5_HDRINFO_HDR_TYPE_FMASK);
 515
 516         if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
 517                 return -EINVAL;
 518
 519         if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
 520                 priv->stats.csum_sw++;
 521         } else if (next_hdr->csum_info & MAPV5_CSUMINFO_VALID_FLAG) {
 522                 priv->stats.csum_ok++;
 523                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 524         } else {
 525                 priv->stats.csum_valid_unset++;
 526         }
 527
 528         /* Pull csum v5 header */
 529         skb_pull(skb, sizeof(*next_hdr));
 530
 531         return 0;
 532 }