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