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