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