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         /* The trailer checksum *includes* the checksum in the transport
  88          * header.  Adding that to the pseudo checksum will yield 0xffff
  89          * ("negative 0") if the message arrived intact.
  90          */
  91         WARN_ON((__sum16)~pseudo_csum);
  92         csum_value_final = ~csum16_sub(pseudo_csum, (__force __be16)*csum_field);
  93
  94         if (unlikely(!csum_value_final)) {
  95                 switch (ip4h->protocol) {
  96                 case IPPROTO_UDP:
  97                         /* RFC 768 - DL4 1's complement rule for UDP csum 0 */
  98                         csum_value_final = ~csum_value_final;
  99                         break;
 100
 101                 case IPPROTO_TCP:
 102                         /* DL4 Non-RFC compliant TCP checksum found */
 103                         if (*csum_field == (__force __sum16)0xFFFF)
 104                                 csum_value_final = ~csum_value_final;
 105                         break;
 106                 }
 107         }
 108
 109         if (csum_value_final == *csum_field) {
 110                 priv->stats.csum_ok++;
 111                 return 0;
 112         } else {
 113                 priv->stats.csum_validation_failed++;
 114                 return -EINVAL;
 115         }
 116 }
 117
 118 #if IS_ENABLED(CONFIG_IPV6)
 119 static int
 120 rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
 121                                struct rmnet_map_dl_csum_trailer *csum_trailer,
 122                                struct rmnet_priv *priv)
 123 {
 124         struct ipv6hdr *ip6h = (struct ipv6hdr *)skb->data;
 125         void *txporthdr = skb->data + sizeof(*ip6h);
 126         __sum16 *csum_field, pseudo_csum;
 127         __sum16 ip6_payload_csum;
 128         __be16 ip_header_csum;
 129         __sum16 csum_value_final;
 130         u32 length;
 131
 132         /* Checksum offload is only supported for UDP and TCP protocols;
 133          * the packet cannot include any IPv6 extension headers
 134          */
 135         csum_field = rmnet_map_get_csum_field(ip6h->nexthdr, txporthdr);
 136         if (!csum_field) {
 137                 priv->stats.csum_err_invalid_transport++;
 138                 return -EPROTONOSUPPORT;
 139         }
 140
 141         /* The checksum value in the trailer is computed over the entire
 142          * IP packet, including the IP header and payload.  To derive the
 143          * transport checksum from this, we first subract the contribution
 144          * of the IP header from the trailer checksum.  We then add the
 145          * checksum computed over the pseudo header.
 146          */
 147         ip_header_csum = (__force __be16)ip_fast_csum(ip6h, sizeof(*ip6h) / 4);
 148         ip6_payload_csum = ~csum16_sub((__force __sum16)csum_trailer->csum_value,
 149                                        ip_header_csum);
 150
 151         length = (ip6h->nexthdr == IPPROTO_UDP) ?
 152                  ntohs(((struct udphdr *)txporthdr)->len) :
 153                  ntohs(ip6h->payload_len);
 154         pseudo_csum = ~csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 155                                        length, ip6h->nexthdr, 0);
 156         pseudo_csum = csum16_add(ip6_payload_csum, (__force __be16)pseudo_csum);
 157
 158         /* Adding the payload checksum to the pseudo checksum yields 0xffff
 159          * ("negative 0") if the message arrived intact.
 160          */
 161         WARN_ON((__sum16)~pseudo_csum);
 162         csum_value_final = ~csum16_sub(pseudo_csum, (__force __be16)*csum_field);
 163
 164         if (unlikely(csum_value_final == 0)) {
 165                 switch (ip6h->nexthdr) {
 166                 case IPPROTO_UDP:
 167                         /* RFC 2460 section 8.1
 168                          * DL6 One's complement rule for UDP checksum 0
 169                          */
 170                         csum_value_final = ~csum_value_final;
 171                         break;
 172
 173                 case IPPROTO_TCP:
 174                         /* DL6 Non-RFC compliant TCP checksum found */
 175                         if (*csum_field == (__force __sum16)0xFFFF)
 176                                 csum_value_final = ~csum_value_final;
 177                         break;
 178                 }
 179         }
 180
 181         if (csum_value_final == *csum_field) {
 182                 priv->stats.csum_ok++;
 183                 return 0;
 184         } else {
 185                 priv->stats.csum_validation_failed++;
 186                 return -EINVAL;
 187         }
 188 }
 189 #endif
 190
 191 static void rmnet_map_complement_ipv4_txporthdr_csum_field(void *iphdr)
 192 {
 193         struct iphdr *ip4h = (struct iphdr *)iphdr;
 194         void *txphdr;
 195         u16 *csum;
 196
 197         txphdr = iphdr + ip4h->ihl * 4;
 198
 199         if (ip4h->protocol == IPPROTO_TCP || ip4h->protocol == IPPROTO_UDP) {
 200                 csum = (u16 *)rmnet_map_get_csum_field(ip4h->protocol, txphdr);
 201                 *csum = ~(*csum);
 202         }
 203 }
 204
 205 static void
 206 rmnet_map_ipv4_ul_csum_header(struct iphdr *iphdr,
 207                               struct rmnet_map_ul_csum_header *ul_header,
 208                               struct sk_buff *skb)
 209 {
 210         u16 val;
 211
 212         val = MAP_CSUM_UL_ENABLED_FLAG;
 213         if (iphdr->protocol == IPPROTO_UDP)
 214                 val |= MAP_CSUM_UL_UDP_FLAG;
 215         val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK;
 216
 217         ul_header->csum_start_offset = htons(skb_network_header_len(skb));
 218         ul_header->csum_info = htons(val);
 219
 220         skb->ip_summed = CHECKSUM_NONE;
 221
 222         rmnet_map_complement_ipv4_txporthdr_csum_field(iphdr);
 223 }
 224
 225 #if IS_ENABLED(CONFIG_IPV6)
 226 static void rmnet_map_complement_ipv6_txporthdr_csum_field(void *ip6hdr)
 227 {
 228         struct ipv6hdr *ip6h = (struct ipv6hdr *)ip6hdr;
 229         void *txphdr;
 230         u16 *csum;
 231
 232         txphdr = ip6hdr + sizeof(struct ipv6hdr);
 233
 234         if (ip6h->nexthdr == IPPROTO_TCP || ip6h->nexthdr == IPPROTO_UDP) {
 235                 csum = (u16 *)rmnet_map_get_csum_field(ip6h->nexthdr, txphdr);
 236                 *csum = ~(*csum);
 237         }
 238 }
 239
 240 static void
 241 rmnet_map_ipv6_ul_csum_header(struct ipv6hdr *ipv6hdr,
 242                               struct rmnet_map_ul_csum_header *ul_header,
 243                               struct sk_buff *skb)
 244 {
 245         u16 val;
 246
 247         val = MAP_CSUM_UL_ENABLED_FLAG;
 248         if (ipv6hdr->nexthdr == IPPROTO_UDP)
 249                 val |= MAP_CSUM_UL_UDP_FLAG;
 250         val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK;
 251
 252         ul_header->csum_start_offset = htons(skb_network_header_len(skb));
 253         ul_header->csum_info = htons(val);
 254
 255         skb->ip_summed = CHECKSUM_NONE;
 256
 257         rmnet_map_complement_ipv6_txporthdr_csum_field(ipv6hdr);
 258 }
 259 #endif
 260
 261 static void rmnet_map_v5_checksum_uplink_packet(struct sk_buff *skb,
 262                                                 struct rmnet_port *port,
 263                                                 struct net_device *orig_dev)
 264 {
 265         struct rmnet_priv *priv = netdev_priv(orig_dev);
 266         struct rmnet_map_v5_csum_header *ul_header;
 267
 268         ul_header = skb_push(skb, sizeof(*ul_header));
 269         memset(ul_header, 0, sizeof(*ul_header));
 270         ul_header->header_info = u8_encode_bits(RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD,
 271                                                 MAPV5_HDRINFO_HDR_TYPE_FMASK);
 272
 273         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 274                 void *iph = ip_hdr(skb);
 275                 __sum16 *check;
 276                 void *trans;
 277                 u8 proto;
 278
 279                 if (skb->protocol == htons(ETH_P_IP)) {
 280                         u16 ip_len = ((struct iphdr *)iph)->ihl * 4;
 281
 282                         proto = ((struct iphdr *)iph)->protocol;
 283                         trans = iph + ip_len;
 284                 } else if (IS_ENABLED(CONFIG_IPV6) &&
 285                            skb->protocol == htons(ETH_P_IPV6)) {
 286                         u16 ip_len = sizeof(struct ipv6hdr);
 287
 288                         proto = ((struct ipv6hdr *)iph)->nexthdr;
 289                         trans = iph + ip_len;
 290                 } else {
 291                         priv->stats.csum_err_invalid_ip_version++;
 292                         goto sw_csum;
 293                 }
 294
 295                 check = rmnet_map_get_csum_field(proto, trans);
 296                 if (check) {
 297                         skb->ip_summed = CHECKSUM_NONE;
 298                         /* Ask for checksum offloading */
 299                         ul_header->csum_info |= MAPV5_CSUMINFO_VALID_FLAG;
 300                         priv->stats.csum_hw++;
 301                         return;
 302                 }
 303         }
 304
 305 sw_csum:
 306         priv->stats.csum_sw++;
 307 }
 308
 309 /* Adds MAP header to front of skb->data
 310  * Padding is calculated and set appropriately in MAP header. Mux ID is
 311  * initialized to 0.
 312  */
 313 struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb,
 314                                                   int hdrlen,
 315                                                   struct rmnet_port *port,
 316                                                   int pad)
 317 {
 318         struct rmnet_map_header *map_header;
 319         u32 padding, map_datalen;
 320         u8 *padbytes;
 321
 322         map_datalen = skb->len - hdrlen;
 323         map_header = (struct rmnet_map_header *)
 324                         skb_push(skb, sizeof(struct rmnet_map_header));
 325         memset(map_header, 0, sizeof(struct rmnet_map_header));
 326
 327         /* Set next_hdr bit for csum offload packets */
 328         if (port->data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5)
 329                 map_header->flags |= MAP_NEXT_HEADER_FLAG;
 330
 331         if (pad == RMNET_MAP_NO_PAD_BYTES) {
 332                 map_header->pkt_len = htons(map_datalen);
 333                 return map_header;
 334         }
 335
 336         BUILD_BUG_ON(MAP_PAD_LEN_MASK < 3);
 337         padding = ALIGN(map_datalen, 4) - map_datalen;
 338
 339         if (padding == 0)
 340                 goto done;
 341
 342         if (skb_tailroom(skb) < padding)
 343                 return NULL;
 344
 345         padbytes = (u8 *)skb_put(skb, padding);
 346         memset(padbytes, 0, padding);
 347
 348 done:
 349         map_header->pkt_len = htons(map_datalen + padding);
 350         /* This is a data packet, so the CMD bit is 0 */
 351         map_header->flags = padding & MAP_PAD_LEN_MASK;
 352
 353         return map_header;
 354 }
 355
 356 /* Deaggregates a single packet
 357  * A whole new buffer is allocated for each portion of an aggregated frame.
 358  * Caller should keep calling deaggregate() on the source skb until 0 is
 359  * returned, indicating that there are no more packets to deaggregate. Caller
 360  * is responsible for freeing the original skb.
 361  */
 362 struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
 363                                       struct rmnet_port *port)
 364 {
 365         struct rmnet_map_v5_csum_header *next_hdr = NULL;
 366         struct rmnet_map_header *maph;
 367         void *data = skb->data;
 368         struct sk_buff *skbn;
 369         u8 nexthdr_type;
 370         u32 packet_len;
 371
 372         if (skb->len == 0)
 373                 return NULL;
 374
 375         maph = (struct rmnet_map_header *)skb->data;
 376         packet_len = ntohs(maph->pkt_len) + sizeof(*maph);
 377
 378         if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) {
 379                 packet_len += sizeof(struct rmnet_map_dl_csum_trailer);
 380         } else if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) {
 381                 if (!(maph->flags & MAP_CMD_FLAG)) {
 382                         packet_len += sizeof(*next_hdr);
 383                         if (maph->flags & MAP_NEXT_HEADER_FLAG)
 384                                 next_hdr = data + sizeof(*maph);
 385                         else
 386                                 /* Mapv5 data pkt without csum hdr is invalid */
 387                                 return NULL;
 388                 }
 389         }
 390
 391         if (((int)skb->len - (int)packet_len) < 0)
 392                 return NULL;
 393
 394         /* Some hardware can send us empty frames. Catch them */
 395         if (!maph->pkt_len)
 396                 return NULL;
 397
 398         if (next_hdr) {
 399                 nexthdr_type = u8_get_bits(next_hdr->header_info,
 400                                            MAPV5_HDRINFO_HDR_TYPE_FMASK);
 401                 if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
 402                         return NULL;
 403         }
 404
 405         skbn = alloc_skb(packet_len + RMNET_MAP_DEAGGR_SPACING, GFP_ATOMIC);
 406         if (!skbn)
 407                 return NULL;
 408
 409         skb_reserve(skbn, RMNET_MAP_DEAGGR_HEADROOM);
 410         skb_put(skbn, packet_len);
 411         memcpy(skbn->data, skb->data, packet_len);
 412         skb_pull(skb, packet_len);
 413
 414         return skbn;
 415 }
 416
 417 /* Validates packet checksums. Function takes a pointer to
 418  * the beginning of a buffer which contains the IP payload +
 419  * padding + checksum trailer.
 420  * Only IPv4 and IPv6 are supported along with TCP & UDP.
 421  * Fragmented or tunneled packets are not supported.
 422  */
 423 int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len)
 424 {
 425         struct rmnet_priv *priv = netdev_priv(skb->dev);
 426         struct rmnet_map_dl_csum_trailer *csum_trailer;
 427
 428         if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
 429                 priv->stats.csum_sw++;
 430                 return -EOPNOTSUPP;
 431         }
 432
 433         csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len);
 434
 435         if (!(csum_trailer->flags & MAP_CSUM_DL_VALID_FLAG)) {
 436                 priv->stats.csum_valid_unset++;
 437                 return -EINVAL;
 438         }
 439
 440         if (skb->protocol == htons(ETH_P_IP))
 441                 return rmnet_map_ipv4_dl_csum_trailer(skb, csum_trailer, priv);
 442
 443         if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6))
 444                 return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer, priv);
 445
 446         priv->stats.csum_err_invalid_ip_version++;
 447
 448         return -EPROTONOSUPPORT;
 449 }
 450
 451 static void rmnet_map_v4_checksum_uplink_packet(struct sk_buff *skb,
 452                                                 struct net_device *orig_dev)
 453 {
 454         struct rmnet_priv *priv = netdev_priv(orig_dev);
 455         struct rmnet_map_ul_csum_header *ul_header;
 456         void *iphdr;
 457
 458         ul_header = (struct rmnet_map_ul_csum_header *)
 459                     skb_push(skb, sizeof(struct rmnet_map_ul_csum_header));
 460
 461         if (unlikely(!(orig_dev->features &
 462                      (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM))))
 463                 goto sw_csum;
 464
 465         if (skb->ip_summed != CHECKSUM_PARTIAL)
 466                 goto sw_csum;
 467
 468         iphdr = (char *)ul_header +
 469                 sizeof(struct rmnet_map_ul_csum_header);
 470
 471         if (skb->protocol == htons(ETH_P_IP)) {
 472                 rmnet_map_ipv4_ul_csum_header(iphdr, ul_header, skb);
 473                 priv->stats.csum_hw++;
 474                 return;
 475         }
 476
 477         if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) {
 478                 rmnet_map_ipv6_ul_csum_header(iphdr, ul_header, skb);
 479                 priv->stats.csum_hw++;
 480                 return;
 481         }
 482
 483         priv->stats.csum_err_invalid_ip_version++;
 484
 485 sw_csum:
 486         memset(ul_header, 0, sizeof(*ul_header));
 487
 488         priv->stats.csum_sw++;
 489 }
 490
 491 /* Generates UL checksum meta info header for IPv4 and IPv6 over TCP and UDP
 492  * packets that are supported for UL checksum offload.
 493  */
 494 void rmnet_map_checksum_uplink_packet(struct sk_buff *skb,
 495                                       struct rmnet_port *port,
 496                                       struct net_device *orig_dev,
 497                                       int csum_type)
 498 {
 499         switch (csum_type) {
 500         case RMNET_FLAGS_EGRESS_MAP_CKSUMV4:
 501                 rmnet_map_v4_checksum_uplink_packet(skb, orig_dev);
 502                 break;
 503         case RMNET_FLAGS_EGRESS_MAP_CKSUMV5:
 504                 rmnet_map_v5_checksum_uplink_packet(skb, port, orig_dev);
 505                 break;
 506         default:
 507                 break;
 508         }
 509 }
 510
 511 /* Process a MAPv5 packet header */
 512 int rmnet_map_process_next_hdr_packet(struct sk_buff *skb,
 513                                       u16 len)
 514 {
 515         struct rmnet_priv *priv = netdev_priv(skb->dev);
 516         struct rmnet_map_v5_csum_header *next_hdr;
 517         u8 nexthdr_type;
 518
 519         next_hdr = (struct rmnet_map_v5_csum_header *)(skb->data +
 520                         sizeof(struct rmnet_map_header));
 521
 522         nexthdr_type = u8_get_bits(next_hdr->header_info,
 523                                    MAPV5_HDRINFO_HDR_TYPE_FMASK);
 524
 525         if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
 526                 return -EINVAL;
 527
 528         if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
 529                 priv->stats.csum_sw++;
 530         } else if (next_hdr->csum_info & MAPV5_CSUMINFO_VALID_FLAG) {
 531                 priv->stats.csum_ok++;
 532                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 533         } else {
 534                 priv->stats.csum_valid_unset++;
 535         }
 536
 537         /* Pull csum v5 header */
 538         skb_pull(skb, sizeof(*next_hdr));
 539
 540         return 0;
 541 }