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(void *iphdr) 167 { 168 struct iphdr *ip4h = (struct iphdr *)iphdr; 169 void *txphdr; 170 u16 *csum; 171 172 txphdr = iphdr + ip4h->ihl * 4; 173 174 if (ip4h->protocol == IPPROTO_TCP || ip4h->protocol == IPPROTO_UDP) { 175 csum = (u16 *)rmnet_map_get_csum_field(ip4h->protocol, txphdr); 176 *csum = ~(*csum); 177 } 178 } 179 180 static void 181 rmnet_map_ipv4_ul_csum_header(struct iphdr *iphdr, 182 struct rmnet_map_ul_csum_header *ul_header, 183 struct sk_buff *skb) 184 { 185 u16 val; 186 187 val = MAP_CSUM_UL_ENABLED_FLAG; 188 if (iphdr->protocol == IPPROTO_UDP) 189 val |= MAP_CSUM_UL_UDP_FLAG; 190 val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK; 191 192 ul_header->csum_start_offset = htons(skb_network_header_len(skb)); 193 ul_header->csum_info = htons(val); 194 195 skb->ip_summed = CHECKSUM_NONE; 196 197 rmnet_map_complement_ipv4_txporthdr_csum_field(iphdr); 198 } 199 200 #if IS_ENABLED(CONFIG_IPV6) 201 static void rmnet_map_complement_ipv6_txporthdr_csum_field(void *ip6hdr) 202 { 203 struct ipv6hdr *ip6h = (struct ipv6hdr *)ip6hdr; 204 void *txphdr; 205 u16 *csum; 206 207 txphdr = ip6hdr + sizeof(struct ipv6hdr); 208 209 if (ip6h->nexthdr == IPPROTO_TCP || ip6h->nexthdr == IPPROTO_UDP) { 210 csum = (u16 *)rmnet_map_get_csum_field(ip6h->nexthdr, txphdr); 211 *csum = ~(*csum); 212 } 213 } 214 215 static void 216 rmnet_map_ipv6_ul_csum_header(struct ipv6hdr *ipv6hdr, 217 struct rmnet_map_ul_csum_header *ul_header, 218 struct sk_buff *skb) 219 { 220 u16 val; 221 222 val = MAP_CSUM_UL_ENABLED_FLAG; 223 if (ipv6hdr->nexthdr == IPPROTO_UDP) 224 val |= MAP_CSUM_UL_UDP_FLAG; 225 val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK; 226 227 ul_header->csum_start_offset = htons(skb_network_header_len(skb)); 228 ul_header->csum_info = htons(val); 229 230 skb->ip_summed = CHECKSUM_NONE; 231 232 rmnet_map_complement_ipv6_txporthdr_csum_field(ipv6hdr); 233 } 234 #else 235 static void 236 rmnet_map_ipv6_ul_csum_header(void *ip6hdr, 237 struct rmnet_map_ul_csum_header *ul_header, 238 struct sk_buff *skb) 239 { 240 } 241 #endif 242 243 static void rmnet_map_v5_checksum_uplink_packet(struct sk_buff *skb, 244 struct rmnet_port *port, 245 struct net_device *orig_dev) 246 { 247 struct rmnet_priv *priv = netdev_priv(orig_dev); 248 struct rmnet_map_v5_csum_header *ul_header; 249 250 ul_header = skb_push(skb, sizeof(*ul_header)); 251 memset(ul_header, 0, sizeof(*ul_header)); 252 ul_header->header_info = u8_encode_bits(RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD, 253 MAPV5_HDRINFO_HDR_TYPE_FMASK); 254 255 if (skb->ip_summed == CHECKSUM_PARTIAL) { 256 void *iph = ip_hdr(skb); 257 __sum16 *check; 258 void *trans; 259 u8 proto; 260 261 if (skb->protocol == htons(ETH_P_IP)) { 262 u16 ip_len = ((struct iphdr *)iph)->ihl * 4; 263 264 proto = ((struct iphdr *)iph)->protocol; 265 trans = iph + ip_len; 266 } else if (IS_ENABLED(CONFIG_IPV6) && 267 skb->protocol == htons(ETH_P_IPV6)) { 268 u16 ip_len = sizeof(struct ipv6hdr); 269 270 proto = ((struct ipv6hdr *)iph)->nexthdr; 271 trans = iph + ip_len; 272 } else { 273 priv->stats.csum_err_invalid_ip_version++; 274 goto sw_csum; 275 } 276 277 check = rmnet_map_get_csum_field(proto, trans); 278 if (check) { 279 skb->ip_summed = CHECKSUM_NONE; 280 /* Ask for checksum offloading */ 281 ul_header->csum_info |= MAPV5_CSUMINFO_VALID_FLAG; 282 priv->stats.csum_hw++; 283 return; 284 } 285 } 286 287 sw_csum: 288 priv->stats.csum_sw++; 289 } 290 291 /* Adds MAP header to front of skb->data 292 * Padding is calculated and set appropriately in MAP header. Mux ID is 293 * initialized to 0. 294 */ 295 struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb, 296 int hdrlen, 297 struct rmnet_port *port, 298 int pad) 299 { 300 struct rmnet_map_header *map_header; 301 u32 padding, map_datalen; 302 u8 *padbytes; 303 304 map_datalen = skb->len - hdrlen; 305 map_header = (struct rmnet_map_header *) 306 skb_push(skb, sizeof(struct rmnet_map_header)); 307 memset(map_header, 0, sizeof(struct rmnet_map_header)); 308 309 /* Set next_hdr bit for csum offload packets */ 310 if (port->data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5) 311 map_header->flags |= MAP_NEXT_HEADER_FLAG; 312 313 if (pad == RMNET_MAP_NO_PAD_BYTES) { 314 map_header->pkt_len = htons(map_datalen); 315 return map_header; 316 } 317 318 BUILD_BUG_ON(MAP_PAD_LEN_MASK < 3); 319 padding = ALIGN(map_datalen, 4) - map_datalen; 320 321 if (padding == 0) 322 goto done; 323 324 if (skb_tailroom(skb) < padding) 325 return NULL; 326 327 padbytes = (u8 *)skb_put(skb, padding); 328 memset(padbytes, 0, padding); 329 330 done: 331 map_header->pkt_len = htons(map_datalen + padding); 332 /* This is a data packet, so the CMD bit is 0 */ 333 map_header->flags = padding & MAP_PAD_LEN_MASK; 334 335 return map_header; 336 } 337 338 /* Deaggregates a single packet 339 * A whole new buffer is allocated for each portion of an aggregated frame. 340 * Caller should keep calling deaggregate() on the source skb until 0 is 341 * returned, indicating that there are no more packets to deaggregate. Caller 342 * is responsible for freeing the original skb. 343 */ 344 struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb, 345 struct rmnet_port *port) 346 { 347 struct rmnet_map_v5_csum_header *next_hdr = NULL; 348 struct rmnet_map_header *maph; 349 void *data = skb->data; 350 struct sk_buff *skbn; 351 u8 nexthdr_type; 352 u32 packet_len; 353 354 if (skb->len == 0) 355 return NULL; 356 357 maph = (struct rmnet_map_header *)skb->data; 358 packet_len = ntohs(maph->pkt_len) + sizeof(*maph); 359 360 if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) { 361 packet_len += sizeof(struct rmnet_map_dl_csum_trailer); 362 } else if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) { 363 if (!(maph->flags & MAP_CMD_FLAG)) { 364 packet_len += sizeof(*next_hdr); 365 if (maph->flags & MAP_NEXT_HEADER_FLAG) 366 next_hdr = data + sizeof(*maph); 367 else 368 /* Mapv5 data pkt without csum hdr is invalid */ 369 return NULL; 370 } 371 } 372 373 if (((int)skb->len - (int)packet_len) < 0) 374 return NULL; 375 376 /* Some hardware can send us empty frames. Catch them */ 377 if (!maph->pkt_len) 378 return NULL; 379 380 if (next_hdr) { 381 nexthdr_type = u8_get_bits(next_hdr->header_info, 382 MAPV5_HDRINFO_HDR_TYPE_FMASK); 383 if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD) 384 return NULL; 385 } 386 387 skbn = alloc_skb(packet_len + RMNET_MAP_DEAGGR_SPACING, GFP_ATOMIC); 388 if (!skbn) 389 return NULL; 390 391 skb_reserve(skbn, RMNET_MAP_DEAGGR_HEADROOM); 392 skb_put(skbn, packet_len); 393 memcpy(skbn->data, skb->data, packet_len); 394 skb_pull(skb, packet_len); 395 396 return skbn; 397 } 398 399 /* Validates packet checksums. Function takes a pointer to 400 * the beginning of a buffer which contains the IP payload + 401 * padding + checksum trailer. 402 * Only IPv4 and IPv6 are supported along with TCP & UDP. 403 * Fragmented or tunneled packets are not supported. 404 */ 405 int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len) 406 { 407 struct rmnet_priv *priv = netdev_priv(skb->dev); 408 struct rmnet_map_dl_csum_trailer *csum_trailer; 409 410 if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) { 411 priv->stats.csum_sw++; 412 return -EOPNOTSUPP; 413 } 414 415 csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len); 416 417 if (!(csum_trailer->flags & MAP_CSUM_DL_VALID_FLAG)) { 418 priv->stats.csum_valid_unset++; 419 return -EINVAL; 420 } 421 422 if (skb->protocol == htons(ETH_P_IP)) 423 return rmnet_map_ipv4_dl_csum_trailer(skb, csum_trailer, priv); 424 425 if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) 426 return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer, priv); 427 428 priv->stats.csum_err_invalid_ip_version++; 429 430 return -EPROTONOSUPPORT; 431 } 432 433 static void rmnet_map_v4_checksum_uplink_packet(struct sk_buff *skb, 434 struct net_device *orig_dev) 435 { 436 struct rmnet_priv *priv = netdev_priv(orig_dev); 437 struct rmnet_map_ul_csum_header *ul_header; 438 void *iphdr; 439 440 ul_header = (struct rmnet_map_ul_csum_header *) 441 skb_push(skb, sizeof(struct rmnet_map_ul_csum_header)); 442 443 if (unlikely(!(orig_dev->features & 444 (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM)))) 445 goto sw_csum; 446 447 if (skb->ip_summed != CHECKSUM_PARTIAL) 448 goto sw_csum; 449 450 iphdr = (char *)ul_header + 451 sizeof(struct rmnet_map_ul_csum_header); 452 453 if (skb->protocol == htons(ETH_P_IP)) { 454 rmnet_map_ipv4_ul_csum_header(iphdr, ul_header, skb); 455 priv->stats.csum_hw++; 456 return; 457 } 458 459 if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) { 460 rmnet_map_ipv6_ul_csum_header(iphdr, ul_header, skb); 461 priv->stats.csum_hw++; 462 return; 463 } 464 465 priv->stats.csum_err_invalid_ip_version++; 466 467 sw_csum: 468 memset(ul_header, 0, sizeof(*ul_header)); 469 470 priv->stats.csum_sw++; 471 } 472 473 /* Generates UL checksum meta info header for IPv4 and IPv6 over TCP and UDP 474 * packets that are supported for UL checksum offload. 475 */ 476 void rmnet_map_checksum_uplink_packet(struct sk_buff *skb, 477 struct rmnet_port *port, 478 struct net_device *orig_dev, 479 int csum_type) 480 { 481 switch (csum_type) { 482 case RMNET_FLAGS_EGRESS_MAP_CKSUMV4: 483 rmnet_map_v4_checksum_uplink_packet(skb, orig_dev); 484 break; 485 case RMNET_FLAGS_EGRESS_MAP_CKSUMV5: 486 rmnet_map_v5_checksum_uplink_packet(skb, port, orig_dev); 487 break; 488 default: 489 break; 490 } 491 } 492 493 /* Process a MAPv5 packet header */ 494 int rmnet_map_process_next_hdr_packet(struct sk_buff *skb, 495 u16 len) 496 { 497 struct rmnet_priv *priv = netdev_priv(skb->dev); 498 struct rmnet_map_v5_csum_header *next_hdr; 499 u8 nexthdr_type; 500 501 next_hdr = (struct rmnet_map_v5_csum_header *)(skb->data + 502 sizeof(struct rmnet_map_header)); 503 504 nexthdr_type = u8_get_bits(next_hdr->header_info, 505 MAPV5_HDRINFO_HDR_TYPE_FMASK); 506 507 if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD) 508 return -EINVAL; 509 510 if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) { 511 priv->stats.csum_sw++; 512 } else if (next_hdr->csum_info & MAPV5_CSUMINFO_VALID_FLAG) { 513 priv->stats.csum_ok++; 514 skb->ip_summed = CHECKSUM_UNNECESSARY; 515 } else { 516 priv->stats.csum_valid_unset++; 517 } 518 519 /* Pull csum v5 header */ 520 skb_pull(skb, sizeof(*next_hdr)); 521 522 return 0; 523 } 524