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         u8 *padbytes;
 302
 303         map_datalen = skb->len - hdrlen;
 304         map_header = (struct rmnet_map_header *)
 305                         skb_push(skb, sizeof(struct rmnet_map_header));
 306         memset(map_header, 0, sizeof(struct rmnet_map_header));
 307
 308         /* Set next_hdr bit for csum offload packets */
 309         if (port->data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5)
 310                 map_header->flags |= MAP_NEXT_HEADER_FLAG;
 311
 312         if (pad == RMNET_MAP_NO_PAD_BYTES) {
 313                 map_header->pkt_len = htons(map_datalen);
 314                 return map_header;
 315         }
 316
 317         BUILD_BUG_ON(MAP_PAD_LEN_MASK < 3);
 318         padding = ALIGN(map_datalen, 4) - map_datalen;
 319
 320         if (padding == 0)
 321                 goto done;
 322
 323         if (skb_tailroom(skb) < padding)
 324                 return NULL;
 325
 326         padbytes = (u8 *)skb_put(skb, padding);
 327         memset(padbytes, 0, padding);
 328
 329 done:
 330         map_header->pkt_len = htons(map_datalen + padding);
 331         /* This is a data packet, so the CMD bit is 0 */
 332         map_header->flags = padding & MAP_PAD_LEN_MASK;
 333
 334         return map_header;
 335 }
 336
 337 /* Deaggregates a single packet
 338  * A whole new buffer is allocated for each portion of an aggregated frame.
 339  * Caller should keep calling deaggregate() on the source skb until 0 is
 340  * returned, indicating that there are no more packets to deaggregate. Caller
 341  * is responsible for freeing the original skb.
 342  */
 343 struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
 344                                       struct rmnet_port *port)
 345 {
 346         struct rmnet_map_v5_csum_header *next_hdr = NULL;
 347         struct rmnet_map_header *maph;
 348         void *data = skb->data;
 349         struct sk_buff *skbn;
 350         u8 nexthdr_type;
 351         u32 packet_len;
 352
 353         if (skb->len == 0)
 354                 return NULL;
 355
 356         maph = (struct rmnet_map_header *)skb->data;
 357         packet_len = ntohs(maph->pkt_len) + sizeof(*maph);
 358
 359         if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) {
 360                 packet_len += sizeof(struct rmnet_map_dl_csum_trailer);
 361         } else if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) {
 362                 if (!(maph->flags & MAP_CMD_FLAG)) {
 363                         packet_len += sizeof(*next_hdr);
 364                         if (maph->flags & MAP_NEXT_HEADER_FLAG)
 365                                 next_hdr = data + sizeof(*maph);
 366                         else
 367                                 /* Mapv5 data pkt without csum hdr is invalid */
 368                                 return NULL;
 369                 }
 370         }
 371
 372         if (((int)skb->len - (int)packet_len) < 0)
 373                 return NULL;
 374
 375         /* Some hardware can send us empty frames. Catch them */
 376         if (!maph->pkt_len)
 377                 return NULL;
 378
 379         if (next_hdr) {
 380                 nexthdr_type = u8_get_bits(next_hdr->header_info,
 381                                            MAPV5_HDRINFO_HDR_TYPE_FMASK);
 382                 if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
 383                         return NULL;
 384         }
 385
 386         skbn = alloc_skb(packet_len + RMNET_MAP_DEAGGR_SPACING, GFP_ATOMIC);
 387         if (!skbn)
 388                 return NULL;
 389
 390         skb_reserve(skbn, RMNET_MAP_DEAGGR_HEADROOM);
 391         skb_put(skbn, packet_len);
 392         memcpy(skbn->data, skb->data, packet_len);
 393         skb_pull(skb, packet_len);
 394
 395         return skbn;
 396 }
 397
 398 /* Validates packet checksums. Function takes a pointer to
 399  * the beginning of a buffer which contains the IP payload +
 400  * padding + checksum trailer.
 401  * Only IPv4 and IPv6 are supported along with TCP & UDP.
 402  * Fragmented or tunneled packets are not supported.
 403  */
 404 int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len)
 405 {
 406         struct rmnet_priv *priv = netdev_priv(skb->dev);
 407         struct rmnet_map_dl_csum_trailer *csum_trailer;
 408
 409         if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
 410                 priv->stats.csum_sw++;
 411                 return -EOPNOTSUPP;
 412         }
 413
 414         csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len);
 415
 416         if (!(csum_trailer->flags & MAP_CSUM_DL_VALID_FLAG)) {
 417                 priv->stats.csum_valid_unset++;
 418                 return -EINVAL;
 419         }
 420
 421         if (skb->protocol == htons(ETH_P_IP))
 422                 return rmnet_map_ipv4_dl_csum_trailer(skb, csum_trailer, priv);
 423
 424         if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6))
 425                 return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer, priv);
 426
 427         priv->stats.csum_err_invalid_ip_version++;
 428
 429         return -EPROTONOSUPPORT;
 430 }
 431
 432 static void rmnet_map_v4_checksum_uplink_packet(struct sk_buff *skb,
 433                                                 struct net_device *orig_dev)
 434 {
 435         struct rmnet_priv *priv = netdev_priv(orig_dev);
 436         struct rmnet_map_ul_csum_header *ul_header;
 437         void *iphdr;
 438
 439         ul_header = (struct rmnet_map_ul_csum_header *)
 440                     skb_push(skb, sizeof(struct rmnet_map_ul_csum_header));
 441
 442         if (unlikely(!(orig_dev->features &
 443                      (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM))))
 444                 goto sw_csum;
 445
 446         if (skb->ip_summed != CHECKSUM_PARTIAL)
 447                 goto sw_csum;
 448
 449         iphdr = (char *)ul_header +
 450                 sizeof(struct rmnet_map_ul_csum_header);
 451
 452         if (skb->protocol == htons(ETH_P_IP)) {
 453                 rmnet_map_ipv4_ul_csum_header(iphdr, ul_header, skb);
 454                 priv->stats.csum_hw++;
 455                 return;
 456         }
 457
 458         if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) {
 459                 rmnet_map_ipv6_ul_csum_header(iphdr, ul_header, skb);
 460                 priv->stats.csum_hw++;
 461                 return;
 462         }
 463
 464         priv->stats.csum_err_invalid_ip_version++;
 465
 466 sw_csum:
 467         memset(ul_header, 0, sizeof(*ul_header));
 468
 469         priv->stats.csum_sw++;
 470 }
 471
 472 /* Generates UL checksum meta info header for IPv4 and IPv6 over TCP and UDP
 473  * packets that are supported for UL checksum offload.
 474  */
 475 void rmnet_map_checksum_uplink_packet(struct sk_buff *skb,
 476                                       struct rmnet_port *port,
 477                                       struct net_device *orig_dev,
 478                                       int csum_type)
 479 {
 480         switch (csum_type) {
 481         case RMNET_FLAGS_EGRESS_MAP_CKSUMV4:
 482                 rmnet_map_v4_checksum_uplink_packet(skb, orig_dev);
 483                 break;
 484         case RMNET_FLAGS_EGRESS_MAP_CKSUMV5:
 485                 rmnet_map_v5_checksum_uplink_packet(skb, port, orig_dev);
 486                 break;
 487         default:
 488                 break;
 489         }
 490 }
 491
 492 /* Process a MAPv5 packet header */
 493 int rmnet_map_process_next_hdr_packet(struct sk_buff *skb,
 494                                       u16 len)
 495 {
 496         struct rmnet_priv *priv = netdev_priv(skb->dev);
 497         struct rmnet_map_v5_csum_header *next_hdr;
 498         u8 nexthdr_type;
 499
 500         next_hdr = (struct rmnet_map_v5_csum_header *)(skb->data +
 501                         sizeof(struct rmnet_map_header));
 502
 503         nexthdr_type = u8_get_bits(next_hdr->header_info,
 504                                    MAPV5_HDRINFO_HDR_TYPE_FMASK);
 505
 506         if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
 507                 return -EINVAL;
 508
 509         if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
 510                 priv->stats.csum_sw++;
 511         } else if (next_hdr->csum_info & MAPV5_CSUMINFO_VALID_FLAG) {
 512                 priv->stats.csum_ok++;
 513                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 514         } else {
 515                 priv->stats.csum_valid_unset++;
 516         }
 517
 518         /* Pull csum v5 header */
 519         skb_pull(skb, sizeof(*next_hdr));
 520
 521         return 0;
 522 }