// SPDX-License-Identifier: GPL-2.0-only /* Copyright (c) 2013-2018, 2021, The Linux Foundation. All rights reserved. * * RMNET Data MAP protocol */ #include #include #include #include #include #include "rmnet_config.h" #include "rmnet_map.h" #include "rmnet_private.h" #include "rmnet_vnd.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) { if (protocol == IPPROTO_TCP) return &((struct tcphdr *)txporthdr)->check; if (protocol == IPPROTO_UDP) return &((struct udphdr *)txporthdr)->check; return NULL; } static int rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb, struct rmnet_map_dl_csum_trailer *csum_trailer, struct rmnet_priv *priv) { struct iphdr *ip4h = (struct iphdr *)skb->data; void *txporthdr = skb->data + ip4h->ihl * 4; __sum16 *csum_field, pseudo_csum; __sum16 ip_payload_csum; /* Computing the checksum over just the IPv4 header--including its * checksum field--should yield 0. If it doesn't, the IP header * is bad, so return an error and let the IP layer drop it. */ if (ip_fast_csum(ip4h, ip4h->ihl)) { priv->stats.csum_ip4_header_bad++; return -EINVAL; } /* We don't support checksum offload on IPv4 fragments */ if (ip_is_fragment(ip4h)) { priv->stats.csum_fragmented_pkt++; return -EOPNOTSUPP; } /* Checksum offload is only supported for UDP and TCP protocols */ csum_field = rmnet_map_get_csum_field(ip4h->protocol, txporthdr); if (!csum_field) { priv->stats.csum_err_invalid_transport++; return -EPROTONOSUPPORT; } /* RFC 768: UDP checksum is optional for IPv4, and is 0 if unused */ if (!*csum_field && ip4h->protocol == IPPROTO_UDP) { priv->stats.csum_skipped++; return 0; } /* The checksum value in the trailer is computed over the entire * IP packet, including the IP header and payload. To derive the * transport checksum from this, we first subract the contribution * of the IP header from the trailer checksum. We then add the * checksum computed over the pseudo header. * * We verified above that the IP header contributes zero to the * trailer checksum. Therefore the checksum in the trailer is * just the checksum computed over the IP payload. * If the IP payload arrives intact, adding the pseudo header * checksum to the IP payload checksum will yield 0xffff (negative * zero). This means the trailer checksum and the pseudo checksum * are additive inverses of each other. Put another way, the * message passes the checksum test if the trailer checksum value * is the negated pseudo header checksum. * * Knowing this, we don't even need to examine the transport * header checksum value; it is already accounted for in the * checksum value found in the trailer. */ ip_payload_csum = csum_trailer->csum_value; pseudo_csum = csum_tcpudp_magic(ip4h->saddr, ip4h->daddr, ntohs(ip4h->tot_len) - ip4h->ihl * 4, ip4h->protocol, 0); /* The cast is required to ensure only the low 16 bits are examined */ if (ip_payload_csum != (__sum16)~pseudo_csum) { priv->stats.csum_validation_failed++; return -EINVAL; } priv->stats.csum_ok++; return 0; } #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) { struct ipv6hdr *ip6h = (struct ipv6hdr *)skb->data; void *txporthdr = skb->data + sizeof(*ip6h); __sum16 *csum_field, pseudo_csum; __sum16 ip6_payload_csum; __be16 ip_header_csum; /* Checksum offload is only supported for UDP and TCP protocols; * the packet cannot include any IPv6 extension headers */ csum_field = rmnet_map_get_csum_field(ip6h->nexthdr, txporthdr); if (!csum_field) { priv->stats.csum_err_invalid_transport++; return -EPROTONOSUPPORT; } /* The checksum value in the trailer is computed over the entire * IP packet, including the IP header and payload. To derive the * transport checksum from this, we first subract the contribution * of the IP header from the trailer checksum. We then add the * checksum computed over the pseudo header. */ ip_header_csum = (__force __be16)ip_fast_csum(ip6h, sizeof(*ip6h) / 4); ip6_payload_csum = csum16_sub(csum_trailer->csum_value, ip_header_csum); pseudo_csum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ntohs(ip6h->payload_len), ip6h->nexthdr, 0); /* It's sufficient to compare the IP payload checksum with the * negated pseudo checksum to determine whether the packet * checksum was good. (See further explanation in comments * in rmnet_map_ipv4_dl_csum_trailer()). * * The cast is required to ensure only the low 16 bits are * examined. */ if (ip6_payload_csum != (__sum16)~pseudo_csum) { priv->stats.csum_validation_failed++; return -EINVAL; } priv->stats.csum_ok++; return 0; } #else static int rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb, struct rmnet_map_dl_csum_trailer *csum_trailer, struct rmnet_priv *priv) { return 0; } #endif static void rmnet_map_complement_ipv4_txporthdr_csum_field(struct iphdr *ip4h) { void *txphdr; u16 *csum; txphdr = (void *)ip4h + 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(struct iphdr *iphdr, struct rmnet_map_ul_csum_header *ul_header, struct sk_buff *skb) { u16 val; val = MAP_CSUM_UL_ENABLED_FLAG; if (iphdr->protocol == IPPROTO_UDP) val |= MAP_CSUM_UL_UDP_FLAG; val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK; ul_header->csum_start_offset = htons(skb_network_header_len(skb)); ul_header->csum_info = htons(val); 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(struct ipv6hdr *ip6h) { void *txphdr; u16 *csum; txphdr = ip6h + 1; 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(struct ipv6hdr *ipv6hdr, struct rmnet_map_ul_csum_header *ul_header, struct sk_buff *skb) { u16 val; val = MAP_CSUM_UL_ENABLED_FLAG; if (ipv6hdr->nexthdr == IPPROTO_UDP) val |= MAP_CSUM_UL_UDP_FLAG; val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK; ul_header->csum_start_offset = htons(skb_network_header_len(skb)); ul_header->csum_info = htons(val); skb->ip_summed = CHECKSUM_NONE; rmnet_map_complement_ipv6_txporthdr_csum_field(ipv6hdr); } #else static void rmnet_map_ipv6_ul_csum_header(void *ip6hdr, struct rmnet_map_ul_csum_header *ul_header, struct sk_buff *skb) { } #endif static void rmnet_map_v5_checksum_uplink_packet(struct sk_buff *skb, struct rmnet_port *port, struct net_device *orig_dev) { struct rmnet_priv *priv = netdev_priv(orig_dev); struct rmnet_map_v5_csum_header *ul_header; ul_header = skb_push(skb, sizeof(*ul_header)); memset(ul_header, 0, sizeof(*ul_header)); ul_header->header_info = u8_encode_bits(RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD, MAPV5_HDRINFO_HDR_TYPE_FMASK); if (skb->ip_summed == CHECKSUM_PARTIAL) { void *iph = ip_hdr(skb); __sum16 *check; void *trans; u8 proto; if (skb->protocol == htons(ETH_P_IP)) { u16 ip_len = ((struct iphdr *)iph)->ihl * 4; proto = ((struct iphdr *)iph)->protocol; trans = iph + ip_len; } else if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) { u16 ip_len = sizeof(struct ipv6hdr); proto = ((struct ipv6hdr *)iph)->nexthdr; trans = iph + ip_len; } else { priv->stats.csum_err_invalid_ip_version++; goto sw_csum; } check = rmnet_map_get_csum_field(proto, trans); if (check) { skb->ip_summed = CHECKSUM_NONE; /* Ask for checksum offloading */ ul_header->csum_info |= MAPV5_CSUMINFO_VALID_FLAG; priv->stats.csum_hw++; return; } } sw_csum: priv->stats.csum_sw++; } /* 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, struct rmnet_port *port, int pad) { struct rmnet_map_header *map_header; u32 padding, map_datalen; 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)); /* Set next_hdr bit for csum offload packets */ if (port->data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5) map_header->flags |= MAP_NEXT_HEADER_FLAG; if (pad == RMNET_MAP_NO_PAD_BYTES) { map_header->pkt_len = htons(map_datalen); return map_header; } BUILD_BUG_ON(MAP_PAD_LEN_MASK < 3); padding = ALIGN(map_datalen, 4) - map_datalen; if (padding == 0) goto done; if (skb_tailroom(skb) < padding) return NULL; skb_put_zero(skb, padding); done: map_header->pkt_len = htons(map_datalen + padding); /* This is a data packet, so the CMD bit is 0 */ map_header->flags = padding & MAP_PAD_LEN_MASK; 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_v5_csum_header *next_hdr = NULL; struct rmnet_map_header *maph; void *data = skb->data; struct sk_buff *skbn; u8 nexthdr_type; u32 packet_len; if (skb->len == 0) return NULL; maph = (struct rmnet_map_header *)skb->data; packet_len = ntohs(maph->pkt_len) + sizeof(*maph); if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) { packet_len += sizeof(struct rmnet_map_dl_csum_trailer); } else if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) { if (!(maph->flags & MAP_CMD_FLAG)) { packet_len += sizeof(*next_hdr); if (maph->flags & MAP_NEXT_HEADER_FLAG) next_hdr = data + sizeof(*maph); else /* Mapv5 data pkt without csum hdr is invalid */ return NULL; } } if (((int)skb->len - (int)packet_len) < 0) return NULL; /* Some hardware can send us empty frames. Catch them */ if (!maph->pkt_len) return NULL; if (next_hdr) { nexthdr_type = u8_get_bits(next_hdr->header_info, MAPV5_HDRINFO_HDR_TYPE_FMASK); if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD) 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->flags & MAP_CSUM_DL_VALID_FLAG)) { 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); if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer, priv); priv->stats.csum_err_invalid_ip_version++; return -EPROTONOSUPPORT; } static void rmnet_map_v4_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) goto sw_csum; 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); priv->stats.csum_hw++; return; } if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) { rmnet_map_ipv6_ul_csum_header(iphdr, ul_header, skb); priv->stats.csum_hw++; return; } priv->stats.csum_err_invalid_ip_version++; sw_csum: memset(ul_header, 0, sizeof(*ul_header)); priv->stats.csum_sw++; } /* 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 rmnet_port *port, struct net_device *orig_dev, int csum_type) { switch (csum_type) { case RMNET_FLAGS_EGRESS_MAP_CKSUMV4: rmnet_map_v4_checksum_uplink_packet(skb, orig_dev); break; case RMNET_FLAGS_EGRESS_MAP_CKSUMV5: rmnet_map_v5_checksum_uplink_packet(skb, port, orig_dev); break; default: break; } } /* Process a MAPv5 packet header */ int rmnet_map_process_next_hdr_packet(struct sk_buff *skb, u16 len) { struct rmnet_priv *priv = netdev_priv(skb->dev); struct rmnet_map_v5_csum_header *next_hdr; u8 nexthdr_type; next_hdr = (struct rmnet_map_v5_csum_header *)(skb->data + sizeof(struct rmnet_map_header)); nexthdr_type = u8_get_bits(next_hdr->header_info, MAPV5_HDRINFO_HDR_TYPE_FMASK); if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD) return -EINVAL; if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) { priv->stats.csum_sw++; } else if (next_hdr->csum_info & MAPV5_CSUMINFO_VALID_FLAG) { priv->stats.csum_ok++; skb->ip_summed = CHECKSUM_UNNECESSARY; } else { priv->stats.csum_valid_unset++; } /* Pull csum v5 header */ skb_pull(skb, sizeof(*next_hdr)); return 0; } #define RMNET_AGG_BYPASS_TIME_NSEC 10000000L static void reset_aggr_params(struct rmnet_port *port) { port->skbagg_head = NULL; port->agg_count = 0; port->agg_state = 0; memset(&port->agg_time, 0, sizeof(struct timespec64)); } static void rmnet_send_skb(struct rmnet_port *port, struct sk_buff *skb) { if (skb_needs_linearize(skb, port->dev->features)) { if (unlikely(__skb_linearize(skb))) { struct rmnet_priv *priv; priv = netdev_priv(port->rmnet_dev); this_cpu_inc(priv->pcpu_stats->stats.tx_drops); dev_kfree_skb_any(skb); return; } } dev_queue_xmit(skb); } static void rmnet_map_flush_tx_packet_work(struct work_struct *work) { struct sk_buff *skb = NULL; struct rmnet_port *port; port = container_of(work, struct rmnet_port, agg_wq); spin_lock_bh(&port->agg_lock); if (likely(port->agg_state == -EINPROGRESS)) { /* Buffer may have already been shipped out */ if (likely(port->skbagg_head)) { skb = port->skbagg_head; reset_aggr_params(port); } port->agg_state = 0; } spin_unlock_bh(&port->agg_lock); if (skb) rmnet_send_skb(port, skb); } static enum hrtimer_restart rmnet_map_flush_tx_packet_queue(struct hrtimer *t) { struct rmnet_port *port; port = container_of(t, struct rmnet_port, hrtimer); schedule_work(&port->agg_wq); return HRTIMER_NORESTART; } unsigned int rmnet_map_tx_aggregate(struct sk_buff *skb, struct rmnet_port *port, struct net_device *orig_dev) { struct timespec64 diff, last; unsigned int len = skb->len; struct sk_buff *agg_skb; int size; spin_lock_bh(&port->agg_lock); memcpy(&last, &port->agg_last, sizeof(struct timespec64)); ktime_get_real_ts64(&port->agg_last); if (!port->skbagg_head) { /* Check to see if we should agg first. If the traffic is very * sparse, don't aggregate. */ new_packet: diff = timespec64_sub(port->agg_last, last); size = port->egress_agg_params.bytes - skb->len; if (size < 0) { /* dropped */ spin_unlock_bh(&port->agg_lock); return 0; } if (diff.tv_sec > 0 || diff.tv_nsec > RMNET_AGG_BYPASS_TIME_NSEC || size == 0) goto no_aggr; port->skbagg_head = skb_copy_expand(skb, 0, size, GFP_ATOMIC); if (!port->skbagg_head) goto no_aggr; dev_kfree_skb_any(skb); port->skbagg_head->protocol = htons(ETH_P_MAP); port->agg_count = 1; ktime_get_real_ts64(&port->agg_time); skb_frag_list_init(port->skbagg_head); goto schedule; } diff = timespec64_sub(port->agg_last, port->agg_time); size = port->egress_agg_params.bytes - port->skbagg_head->len; if (skb->len > size) { agg_skb = port->skbagg_head; reset_aggr_params(port); spin_unlock_bh(&port->agg_lock); hrtimer_cancel(&port->hrtimer); rmnet_send_skb(port, agg_skb); spin_lock_bh(&port->agg_lock); goto new_packet; } if (skb_has_frag_list(port->skbagg_head)) port->skbagg_tail->next = skb; else skb_shinfo(port->skbagg_head)->frag_list = skb; port->skbagg_head->len += skb->len; port->skbagg_head->data_len += skb->len; port->skbagg_head->truesize += skb->truesize; port->skbagg_tail = skb; port->agg_count++; if (diff.tv_sec > 0 || diff.tv_nsec > port->egress_agg_params.time_nsec || port->agg_count >= port->egress_agg_params.count || port->skbagg_head->len == port->egress_agg_params.bytes) { agg_skb = port->skbagg_head; reset_aggr_params(port); spin_unlock_bh(&port->agg_lock); hrtimer_cancel(&port->hrtimer); rmnet_send_skb(port, agg_skb); return len; } schedule: if (!hrtimer_active(&port->hrtimer) && port->agg_state != -EINPROGRESS) { port->agg_state = -EINPROGRESS; hrtimer_start(&port->hrtimer, ns_to_ktime(port->egress_agg_params.time_nsec), HRTIMER_MODE_REL); } spin_unlock_bh(&port->agg_lock); return len; no_aggr: spin_unlock_bh(&port->agg_lock); skb->protocol = htons(ETH_P_MAP); dev_queue_xmit(skb); return len; } void rmnet_map_update_ul_agg_config(struct rmnet_port *port, u32 size, u32 count, u32 time) { spin_lock_bh(&port->agg_lock); port->egress_agg_params.bytes = size; WRITE_ONCE(port->egress_agg_params.count, count); port->egress_agg_params.time_nsec = time * NSEC_PER_USEC; spin_unlock_bh(&port->agg_lock); } void rmnet_map_tx_aggregate_init(struct rmnet_port *port) { hrtimer_init(&port->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); port->hrtimer.function = rmnet_map_flush_tx_packet_queue; spin_lock_init(&port->agg_lock); rmnet_map_update_ul_agg_config(port, 4096, 1, 800); INIT_WORK(&port->agg_wq, rmnet_map_flush_tx_packet_work); } void rmnet_map_tx_aggregate_exit(struct rmnet_port *port) { hrtimer_cancel(&port->hrtimer); cancel_work_sync(&port->agg_wq); spin_lock_bh(&port->agg_lock); if (port->agg_state == -EINPROGRESS) { if (port->skbagg_head) { dev_kfree_skb_any(port->skbagg_head); reset_aggr_params(port); } port->agg_state = 0; } spin_unlock_bh(&port->agg_lock); }