/* Copyright (c) 2013-2018, The Linux Foundation. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 and * only version 2 as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * RMNET Data MAP protocol * */ #include <linux/netdevice.h> #include <linux/ip.h> #include <linux/ipv6.h> #include <net/ip6_checksum.h> #include "rmnet_config.h" #include "rmnet_map.h" #include "rmnet_private.h" #define RMNET_MAP_DEAGGR_SPACING 64 #define RMNET_MAP_DEAGGR_HEADROOM (RMNET_MAP_DEAGGR_SPACING / 2) static __sum16 *rmnet_map_get_csum_field(unsigned char protocol, const void *txporthdr) { __sum16 *check = NULL; switch (protocol) { case IPPROTO_TCP: check = &(((struct tcphdr *)txporthdr)->check); break; case IPPROTO_UDP: check = &(((struct udphdr *)txporthdr)->check); break; default: check = NULL; break; } return check; } static int rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb, struct rmnet_map_dl_csum_trailer *csum_trailer, struct rmnet_priv *priv) { __sum16 *csum_field, csum_temp, pseudo_csum, hdr_csum, ip_payload_csum; u16 csum_value, csum_value_final; struct iphdr *ip4h; void *txporthdr; __be16 addend; ip4h = (struct iphdr *)(skb->data); if ((ntohs(ip4h->frag_off) & IP_MF) || ((ntohs(ip4h->frag_off) & IP_OFFSET) > 0)) { priv->stats.csum_fragmented_pkt++; return -EOPNOTSUPP; } txporthdr = skb->data + ip4h->ihl * 4; csum_field = rmnet_map_get_csum_field(ip4h->protocol, txporthdr); if (!csum_field) { priv->stats.csum_err_invalid_transport++; return -EPROTONOSUPPORT; } /* RFC 768 - Skip IPv4 UDP packets where sender checksum field is 0 */ if (*csum_field == 0 && ip4h->protocol == IPPROTO_UDP) { priv->stats.csum_skipped++; return 0; } csum_value = ~ntohs(csum_trailer->csum_value); hdr_csum = ~ip_fast_csum(ip4h, (int)ip4h->ihl); ip_payload_csum = csum16_sub((__force __sum16)csum_value, (__force __be16)hdr_csum); pseudo_csum = ~csum_tcpudp_magic(ip4h->saddr, ip4h->daddr, ntohs(ip4h->tot_len) - ip4h->ihl * 4, ip4h->protocol, 0); addend = (__force __be16)ntohs((__force __be16)pseudo_csum); pseudo_csum = csum16_add(ip_payload_csum, addend); addend = (__force __be16)ntohs((__force __be16)*csum_field); csum_temp = ~csum16_sub(pseudo_csum, addend); csum_value_final = (__force u16)csum_temp; if (unlikely(csum_value_final == 0)) { switch (ip4h->protocol) { case IPPROTO_UDP: /* RFC 768 - DL4 1's complement rule for UDP csum 0 */ csum_value_final = ~csum_value_final; break; case IPPROTO_TCP: /* DL4 Non-RFC compliant TCP checksum found */ if (*csum_field == (__force __sum16)0xFFFF) csum_value_final = ~csum_value_final; break; } } if (csum_value_final == ntohs((__force __be16)*csum_field)) { priv->stats.csum_ok++; return 0; } else { priv->stats.csum_validation_failed++; return -EINVAL; } } #if IS_ENABLED(CONFIG_IPV6) static int rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb, struct rmnet_map_dl_csum_trailer *csum_trailer, struct rmnet_priv *priv) { __sum16 *csum_field, ip6_payload_csum, pseudo_csum, csum_temp; u16 csum_value, csum_value_final; __be16 ip6_hdr_csum, addend; struct ipv6hdr *ip6h; void *txporthdr; u32 length; ip6h = (struct ipv6hdr *)(skb->data); txporthdr = skb->data + sizeof(struct ipv6hdr); csum_field = rmnet_map_get_csum_field(ip6h->nexthdr, txporthdr); if (!csum_field) { priv->stats.csum_err_invalid_transport++; return -EPROTONOSUPPORT; } csum_value = ~ntohs(csum_trailer->csum_value); ip6_hdr_csum = (__force __be16) ~ntohs((__force __be16)ip_compute_csum(ip6h, (int)(txporthdr - (void *)(skb->data)))); ip6_payload_csum = csum16_sub((__force __sum16)csum_value, ip6_hdr_csum); length = (ip6h->nexthdr == IPPROTO_UDP) ? ntohs(((struct udphdr *)txporthdr)->len) : ntohs(ip6h->payload_len); pseudo_csum = ~(csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, length, ip6h->nexthdr, 0)); addend = (__force __be16)ntohs((__force __be16)pseudo_csum); pseudo_csum = csum16_add(ip6_payload_csum, addend); addend = (__force __be16)ntohs((__force __be16)*csum_field); csum_temp = ~csum16_sub(pseudo_csum, addend); csum_value_final = (__force u16)csum_temp; if (unlikely(csum_value_final == 0)) { switch (ip6h->nexthdr) { case IPPROTO_UDP: /* RFC 2460 section 8.1 * DL6 One's complement rule for UDP checksum 0 */ csum_value_final = ~csum_value_final; break; case IPPROTO_TCP: /* DL6 Non-RFC compliant TCP checksum found */ if (*csum_field == (__force __sum16)0xFFFF) csum_value_final = ~csum_value_final; break; } } if (csum_value_final == ntohs((__force __be16)*csum_field)) { priv->stats.csum_ok++; return 0; } else { priv->stats.csum_validation_failed++; return -EINVAL; } } #endif static void rmnet_map_complement_ipv4_txporthdr_csum_field(void *iphdr) { struct iphdr *ip4h = (struct iphdr *)iphdr; void *txphdr; u16 *csum; txphdr = iphdr + ip4h->ihl * 4; if (ip4h->protocol == IPPROTO_TCP || ip4h->protocol == IPPROTO_UDP) { csum = (u16 *)rmnet_map_get_csum_field(ip4h->protocol, txphdr); *csum = ~(*csum); } } static void rmnet_map_ipv4_ul_csum_header(void *iphdr, struct rmnet_map_ul_csum_header *ul_header, struct sk_buff *skb) { struct iphdr *ip4h = (struct iphdr *)iphdr; __be16 *hdr = (__be16 *)ul_header, offset; offset = htons((__force u16)(skb_transport_header(skb) - (unsigned char *)iphdr)); ul_header->csum_start_offset = offset; ul_header->csum_insert_offset = skb->csum_offset; ul_header->csum_enabled = 1; if (ip4h->protocol == IPPROTO_UDP) ul_header->udp_ind = 1; else ul_header->udp_ind = 0; /* Changing remaining fields to network order */ hdr++; *hdr = htons((__force u16)*hdr); skb->ip_summed = CHECKSUM_NONE; rmnet_map_complement_ipv4_txporthdr_csum_field(iphdr); } #if IS_ENABLED(CONFIG_IPV6) static void rmnet_map_complement_ipv6_txporthdr_csum_field(void *ip6hdr) { struct ipv6hdr *ip6h = (struct ipv6hdr *)ip6hdr; void *txphdr; u16 *csum; txphdr = ip6hdr + sizeof(struct ipv6hdr); if (ip6h->nexthdr == IPPROTO_TCP || ip6h->nexthdr == IPPROTO_UDP) { csum = (u16 *)rmnet_map_get_csum_field(ip6h->nexthdr, txphdr); *csum = ~(*csum); } } static void rmnet_map_ipv6_ul_csum_header(void *ip6hdr, struct rmnet_map_ul_csum_header *ul_header, struct sk_buff *skb) { struct ipv6hdr *ip6h = (struct ipv6hdr *)ip6hdr; __be16 *hdr = (__be16 *)ul_header, offset; offset = htons((__force u16)(skb_transport_header(skb) - (unsigned char *)ip6hdr)); ul_header->csum_start_offset = offset; ul_header->csum_insert_offset = skb->csum_offset; ul_header->csum_enabled = 1; if (ip6h->nexthdr == IPPROTO_UDP) ul_header->udp_ind = 1; else ul_header->udp_ind = 0; /* Changing remaining fields to network order */ hdr++; *hdr = htons((__force u16)*hdr); skb->ip_summed = CHECKSUM_NONE; rmnet_map_complement_ipv6_txporthdr_csum_field(ip6hdr); } #endif /* Adds MAP header to front of skb->data * Padding is calculated and set appropriately in MAP header. Mux ID is * initialized to 0. */ struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb, int hdrlen, int pad) { struct rmnet_map_header *map_header; u32 padding, map_datalen; u8 *padbytes; map_datalen = skb->len - hdrlen; map_header = (struct rmnet_map_header *) skb_push(skb, sizeof(struct rmnet_map_header)); memset(map_header, 0, sizeof(struct rmnet_map_header)); if (pad == RMNET_MAP_NO_PAD_BYTES) { map_header->pkt_len = htons(map_datalen); return map_header; } padding = ALIGN(map_datalen, 4) - map_datalen; if (padding == 0) goto done; if (skb_tailroom(skb) < padding) return NULL; padbytes = (u8 *)skb_put(skb, padding); memset(padbytes, 0, padding); done: map_header->pkt_len = htons(map_datalen + padding); map_header->pad_len = padding & 0x3F; return map_header; } /* Deaggregates a single packet * A whole new buffer is allocated for each portion of an aggregated frame. * Caller should keep calling deaggregate() on the source skb until 0 is * returned, indicating that there are no more packets to deaggregate. Caller * is responsible for freeing the original skb. */ struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb, struct rmnet_port *port) { struct rmnet_map_header *maph; struct sk_buff *skbn; u32 packet_len; if (skb->len == 0) return NULL; maph = (struct rmnet_map_header *)skb->data; packet_len = ntohs(maph->pkt_len) + sizeof(struct rmnet_map_header); if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) packet_len += sizeof(struct rmnet_map_dl_csum_trailer); if (((int)skb->len - (int)packet_len) < 0) return NULL; /* Some hardware can send us empty frames. Catch them */ if (ntohs(maph->pkt_len) == 0) return NULL; skbn = alloc_skb(packet_len + RMNET_MAP_DEAGGR_SPACING, GFP_ATOMIC); if (!skbn) return NULL; skb_reserve(skbn, RMNET_MAP_DEAGGR_HEADROOM); skb_put(skbn, packet_len); memcpy(skbn->data, skb->data, packet_len); skb_pull(skb, packet_len); return skbn; } /* Validates packet checksums. Function takes a pointer to * the beginning of a buffer which contains the IP payload + * padding + checksum trailer. * Only IPv4 and IPv6 are supported along with TCP & UDP. * Fragmented or tunneled packets are not supported. */ int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len) { struct rmnet_priv *priv = netdev_priv(skb->dev); struct rmnet_map_dl_csum_trailer *csum_trailer; if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) { priv->stats.csum_sw++; return -EOPNOTSUPP; } csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len); if (!csum_trailer->valid) { priv->stats.csum_valid_unset++; return -EINVAL; } if (skb->protocol == htons(ETH_P_IP)) { return rmnet_map_ipv4_dl_csum_trailer(skb, csum_trailer, priv); } else if (skb->protocol == htons(ETH_P_IPV6)) { #if IS_ENABLED(CONFIG_IPV6) return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer, priv); #else priv->stats.csum_err_invalid_ip_version++; return -EPROTONOSUPPORT; #endif } else { priv->stats.csum_err_invalid_ip_version++; return -EPROTONOSUPPORT; } return 0; } /* Generates UL checksum meta info header for IPv4 and IPv6 over TCP and UDP * packets that are supported for UL checksum offload. */ void rmnet_map_checksum_uplink_packet(struct sk_buff *skb, struct net_device *orig_dev) { struct rmnet_priv *priv = netdev_priv(orig_dev); struct rmnet_map_ul_csum_header *ul_header; void *iphdr; ul_header = (struct rmnet_map_ul_csum_header *) skb_push(skb, sizeof(struct rmnet_map_ul_csum_header)); if (unlikely(!(orig_dev->features & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM)))) goto sw_csum; if (skb->ip_summed == CHECKSUM_PARTIAL) { iphdr = (char *)ul_header + sizeof(struct rmnet_map_ul_csum_header); if (skb->protocol == htons(ETH_P_IP)) { rmnet_map_ipv4_ul_csum_header(iphdr, ul_header, skb); return; } else if (skb->protocol == htons(ETH_P_IPV6)) { #if IS_ENABLED(CONFIG_IPV6) rmnet_map_ipv6_ul_csum_header(iphdr, ul_header, skb); return; #else priv->stats.csum_err_invalid_ip_version++; goto sw_csum; #endif } else { priv->stats.csum_err_invalid_ip_version++; } } sw_csum: ul_header->csum_start_offset = 0; ul_header->csum_insert_offset = 0; ul_header->csum_enabled = 0; ul_header->udp_ind = 0; priv->stats.csum_sw++; }