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522 lines
14 KiB
522 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* Copyright (c) 2013-2018, 2021, The Linux Foundation. All rights reserved. |
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* |
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* RMNET Data MAP protocol |
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*/ |
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|
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#include <linux/netdevice.h> |
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#include <linux/ip.h> |
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#include <linux/ipv6.h> |
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#include <net/ip6_checksum.h> |
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#include <linux/bitfield.h> |
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#include "rmnet_config.h" |
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#include "rmnet_map.h" |
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#include "rmnet_private.h" |
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#define RMNET_MAP_DEAGGR_SPACING 64 |
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#define RMNET_MAP_DEAGGR_HEADROOM (RMNET_MAP_DEAGGR_SPACING / 2) |
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static __sum16 *rmnet_map_get_csum_field(unsigned char protocol, |
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const void *txporthdr) |
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{ |
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if (protocol == IPPROTO_TCP) |
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return &((struct tcphdr *)txporthdr)->check; |
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|
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if (protocol == IPPROTO_UDP) |
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return &((struct udphdr *)txporthdr)->check; |
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return NULL; |
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} |
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static int |
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rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb, |
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struct rmnet_map_dl_csum_trailer *csum_trailer, |
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struct rmnet_priv *priv) |
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{ |
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struct iphdr *ip4h = (struct iphdr *)skb->data; |
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void *txporthdr = skb->data + ip4h->ihl * 4; |
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__sum16 *csum_field, pseudo_csum; |
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__sum16 ip_payload_csum; |
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|
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/* Computing the checksum over just the IPv4 header--including its |
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* checksum field--should yield 0. If it doesn't, the IP header |
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* is bad, so return an error and let the IP layer drop it. |
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*/ |
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if (ip_fast_csum(ip4h, ip4h->ihl)) { |
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priv->stats.csum_ip4_header_bad++; |
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return -EINVAL; |
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} |
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|
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/* We don't support checksum offload on IPv4 fragments */ |
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if (ip_is_fragment(ip4h)) { |
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priv->stats.csum_fragmented_pkt++; |
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return -EOPNOTSUPP; |
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} |
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/* Checksum offload is only supported for UDP and TCP protocols */ |
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csum_field = rmnet_map_get_csum_field(ip4h->protocol, txporthdr); |
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if (!csum_field) { |
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priv->stats.csum_err_invalid_transport++; |
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return -EPROTONOSUPPORT; |
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} |
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|
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/* RFC 768: UDP checksum is optional for IPv4, and is 0 if unused */ |
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if (!*csum_field && ip4h->protocol == IPPROTO_UDP) { |
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priv->stats.csum_skipped++; |
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return 0; |
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} |
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/* The checksum value in the trailer is computed over the entire |
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* IP packet, including the IP header and payload. To derive the |
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* transport checksum from this, we first subract the contribution |
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* of the IP header from the trailer checksum. We then add the |
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* checksum computed over the pseudo header. |
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* |
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* We verified above that the IP header contributes zero to the |
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* trailer checksum. Therefore the checksum in the trailer is |
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* just the checksum computed over the IP payload. |
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|
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* If the IP payload arrives intact, adding the pseudo header |
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* checksum to the IP payload checksum will yield 0xffff (negative |
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* zero). This means the trailer checksum and the pseudo checksum |
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* are additive inverses of each other. Put another way, the |
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* message passes the checksum test if the trailer checksum value |
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* is the negated pseudo header checksum. |
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* |
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* Knowing this, we don't even need to examine the transport |
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* header checksum value; it is already accounted for in the |
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* checksum value found in the trailer. |
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*/ |
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ip_payload_csum = csum_trailer->csum_value; |
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pseudo_csum = csum_tcpudp_magic(ip4h->saddr, ip4h->daddr, |
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ntohs(ip4h->tot_len) - ip4h->ihl * 4, |
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ip4h->protocol, 0); |
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/* The cast is required to ensure only the low 16 bits are examined */ |
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if (ip_payload_csum != (__sum16)~pseudo_csum) { |
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priv->stats.csum_validation_failed++; |
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return -EINVAL; |
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} |
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priv->stats.csum_ok++; |
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return 0; |
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} |
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#if IS_ENABLED(CONFIG_IPV6) |
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static int |
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rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb, |
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struct rmnet_map_dl_csum_trailer *csum_trailer, |
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struct rmnet_priv *priv) |
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{ |
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struct ipv6hdr *ip6h = (struct ipv6hdr *)skb->data; |
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void *txporthdr = skb->data + sizeof(*ip6h); |
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__sum16 *csum_field, pseudo_csum; |
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__sum16 ip6_payload_csum; |
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__be16 ip_header_csum; |
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/* Checksum offload is only supported for UDP and TCP protocols; |
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* the packet cannot include any IPv6 extension headers |
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*/ |
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csum_field = rmnet_map_get_csum_field(ip6h->nexthdr, txporthdr); |
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if (!csum_field) { |
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priv->stats.csum_err_invalid_transport++; |
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return -EPROTONOSUPPORT; |
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} |
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|
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/* The checksum value in the trailer is computed over the entire |
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* IP packet, including the IP header and payload. To derive the |
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* transport checksum from this, we first subract the contribution |
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* of the IP header from the trailer checksum. We then add the |
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* checksum computed over the pseudo header. |
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*/ |
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ip_header_csum = (__force __be16)ip_fast_csum(ip6h, sizeof(*ip6h) / 4); |
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ip6_payload_csum = csum16_sub(csum_trailer->csum_value, ip_header_csum); |
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pseudo_csum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, |
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ntohs(ip6h->payload_len), |
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ip6h->nexthdr, 0); |
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|
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/* It's sufficient to compare the IP payload checksum with the |
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* negated pseudo checksum to determine whether the packet |
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* checksum was good. (See further explanation in comments |
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* in rmnet_map_ipv4_dl_csum_trailer()). |
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* |
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* The cast is required to ensure only the low 16 bits are |
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* examined. |
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*/ |
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if (ip6_payload_csum != (__sum16)~pseudo_csum) { |
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priv->stats.csum_validation_failed++; |
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return -EINVAL; |
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} |
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priv->stats.csum_ok++; |
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return 0; |
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} |
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#else |
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static int |
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rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb, |
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struct rmnet_map_dl_csum_trailer *csum_trailer, |
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struct rmnet_priv *priv) |
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{ |
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return 0; |
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} |
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#endif |
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static void rmnet_map_complement_ipv4_txporthdr_csum_field(struct iphdr *ip4h) |
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{ |
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void *txphdr; |
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u16 *csum; |
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txphdr = (void *)ip4h + ip4h->ihl * 4; |
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if (ip4h->protocol == IPPROTO_TCP || ip4h->protocol == IPPROTO_UDP) { |
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csum = (u16 *)rmnet_map_get_csum_field(ip4h->protocol, txphdr); |
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*csum = ~(*csum); |
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} |
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} |
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static void |
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rmnet_map_ipv4_ul_csum_header(struct iphdr *iphdr, |
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struct rmnet_map_ul_csum_header *ul_header, |
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struct sk_buff *skb) |
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{ |
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u16 val; |
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val = MAP_CSUM_UL_ENABLED_FLAG; |
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if (iphdr->protocol == IPPROTO_UDP) |
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val |= MAP_CSUM_UL_UDP_FLAG; |
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val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK; |
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ul_header->csum_start_offset = htons(skb_network_header_len(skb)); |
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ul_header->csum_info = htons(val); |
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skb->ip_summed = CHECKSUM_NONE; |
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rmnet_map_complement_ipv4_txporthdr_csum_field(iphdr); |
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} |
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#if IS_ENABLED(CONFIG_IPV6) |
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static void |
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rmnet_map_complement_ipv6_txporthdr_csum_field(struct ipv6hdr *ip6h) |
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{ |
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void *txphdr; |
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u16 *csum; |
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txphdr = ip6h + 1; |
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if (ip6h->nexthdr == IPPROTO_TCP || ip6h->nexthdr == IPPROTO_UDP) { |
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csum = (u16 *)rmnet_map_get_csum_field(ip6h->nexthdr, txphdr); |
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*csum = ~(*csum); |
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} |
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} |
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static void |
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rmnet_map_ipv6_ul_csum_header(struct ipv6hdr *ipv6hdr, |
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struct rmnet_map_ul_csum_header *ul_header, |
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struct sk_buff *skb) |
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{ |
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u16 val; |
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val = MAP_CSUM_UL_ENABLED_FLAG; |
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if (ipv6hdr->nexthdr == IPPROTO_UDP) |
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val |= MAP_CSUM_UL_UDP_FLAG; |
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val |= skb->csum_offset & MAP_CSUM_UL_OFFSET_MASK; |
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ul_header->csum_start_offset = htons(skb_network_header_len(skb)); |
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ul_header->csum_info = htons(val); |
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skb->ip_summed = CHECKSUM_NONE; |
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rmnet_map_complement_ipv6_txporthdr_csum_field(ipv6hdr); |
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} |
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#else |
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static void |
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rmnet_map_ipv6_ul_csum_header(void *ip6hdr, |
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struct rmnet_map_ul_csum_header *ul_header, |
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struct sk_buff *skb) |
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{ |
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} |
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#endif |
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static void rmnet_map_v5_checksum_uplink_packet(struct sk_buff *skb, |
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struct rmnet_port *port, |
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struct net_device *orig_dev) |
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{ |
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struct rmnet_priv *priv = netdev_priv(orig_dev); |
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struct rmnet_map_v5_csum_header *ul_header; |
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ul_header = skb_push(skb, sizeof(*ul_header)); |
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memset(ul_header, 0, sizeof(*ul_header)); |
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ul_header->header_info = u8_encode_bits(RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD, |
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MAPV5_HDRINFO_HDR_TYPE_FMASK); |
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if (skb->ip_summed == CHECKSUM_PARTIAL) { |
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void *iph = ip_hdr(skb); |
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__sum16 *check; |
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void *trans; |
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u8 proto; |
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if (skb->protocol == htons(ETH_P_IP)) { |
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u16 ip_len = ((struct iphdr *)iph)->ihl * 4; |
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proto = ((struct iphdr *)iph)->protocol; |
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trans = iph + ip_len; |
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} else if (IS_ENABLED(CONFIG_IPV6) && |
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skb->protocol == htons(ETH_P_IPV6)) { |
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u16 ip_len = sizeof(struct ipv6hdr); |
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proto = ((struct ipv6hdr *)iph)->nexthdr; |
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trans = iph + ip_len; |
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} else { |
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priv->stats.csum_err_invalid_ip_version++; |
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goto sw_csum; |
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} |
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check = rmnet_map_get_csum_field(proto, trans); |
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if (check) { |
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skb->ip_summed = CHECKSUM_NONE; |
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/* Ask for checksum offloading */ |
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ul_header->csum_info |= MAPV5_CSUMINFO_VALID_FLAG; |
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priv->stats.csum_hw++; |
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return; |
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} |
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} |
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sw_csum: |
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priv->stats.csum_sw++; |
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} |
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/* Adds MAP header to front of skb->data |
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* Padding is calculated and set appropriately in MAP header. Mux ID is |
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* initialized to 0. |
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*/ |
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struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb, |
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int hdrlen, |
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struct rmnet_port *port, |
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int pad) |
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{ |
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struct rmnet_map_header *map_header; |
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u32 padding, map_datalen; |
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u8 *padbytes; |
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map_datalen = skb->len - hdrlen; |
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map_header = (struct rmnet_map_header *) |
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skb_push(skb, sizeof(struct rmnet_map_header)); |
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memset(map_header, 0, sizeof(struct rmnet_map_header)); |
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/* Set next_hdr bit for csum offload packets */ |
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if (port->data_format & RMNET_FLAGS_EGRESS_MAP_CKSUMV5) |
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map_header->flags |= MAP_NEXT_HEADER_FLAG; |
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if (pad == RMNET_MAP_NO_PAD_BYTES) { |
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map_header->pkt_len = htons(map_datalen); |
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return map_header; |
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} |
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BUILD_BUG_ON(MAP_PAD_LEN_MASK < 3); |
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padding = ALIGN(map_datalen, 4) - map_datalen; |
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if (padding == 0) |
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goto done; |
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if (skb_tailroom(skb) < padding) |
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return NULL; |
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padbytes = (u8 *)skb_put(skb, padding); |
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memset(padbytes, 0, padding); |
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done: |
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map_header->pkt_len = htons(map_datalen + padding); |
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/* This is a data packet, so the CMD bit is 0 */ |
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map_header->flags = padding & MAP_PAD_LEN_MASK; |
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return map_header; |
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} |
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|
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/* Deaggregates a single packet |
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* A whole new buffer is allocated for each portion of an aggregated frame. |
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* Caller should keep calling deaggregate() on the source skb until 0 is |
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* returned, indicating that there are no more packets to deaggregate. Caller |
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* is responsible for freeing the original skb. |
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*/ |
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struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb, |
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struct rmnet_port *port) |
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{ |
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struct rmnet_map_v5_csum_header *next_hdr = NULL; |
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struct rmnet_map_header *maph; |
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void *data = skb->data; |
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struct sk_buff *skbn; |
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u8 nexthdr_type; |
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u32 packet_len; |
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if (skb->len == 0) |
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return NULL; |
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maph = (struct rmnet_map_header *)skb->data; |
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packet_len = ntohs(maph->pkt_len) + sizeof(*maph); |
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if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) { |
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packet_len += sizeof(struct rmnet_map_dl_csum_trailer); |
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} else if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) { |
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if (!(maph->flags & MAP_CMD_FLAG)) { |
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packet_len += sizeof(*next_hdr); |
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if (maph->flags & MAP_NEXT_HEADER_FLAG) |
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next_hdr = data + sizeof(*maph); |
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else |
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/* Mapv5 data pkt without csum hdr is invalid */ |
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return NULL; |
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} |
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} |
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if (((int)skb->len - (int)packet_len) < 0) |
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return NULL; |
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/* Some hardware can send us empty frames. Catch them */ |
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if (!maph->pkt_len) |
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return NULL; |
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if (next_hdr) { |
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nexthdr_type = u8_get_bits(next_hdr->header_info, |
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MAPV5_HDRINFO_HDR_TYPE_FMASK); |
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if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD) |
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return NULL; |
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} |
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skbn = alloc_skb(packet_len + RMNET_MAP_DEAGGR_SPACING, GFP_ATOMIC); |
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if (!skbn) |
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return NULL; |
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skb_reserve(skbn, RMNET_MAP_DEAGGR_HEADROOM); |
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skb_put(skbn, packet_len); |
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memcpy(skbn->data, skb->data, packet_len); |
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skb_pull(skb, packet_len); |
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return skbn; |
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} |
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/* Validates packet checksums. Function takes a pointer to |
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* the beginning of a buffer which contains the IP payload + |
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* padding + checksum trailer. |
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* Only IPv4 and IPv6 are supported along with TCP & UDP. |
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* Fragmented or tunneled packets are not supported. |
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*/ |
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int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len) |
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{ |
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struct rmnet_priv *priv = netdev_priv(skb->dev); |
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struct rmnet_map_dl_csum_trailer *csum_trailer; |
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if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) { |
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priv->stats.csum_sw++; |
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return -EOPNOTSUPP; |
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} |
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csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len); |
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if (!(csum_trailer->flags & MAP_CSUM_DL_VALID_FLAG)) { |
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priv->stats.csum_valid_unset++; |
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return -EINVAL; |
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} |
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if (skb->protocol == htons(ETH_P_IP)) |
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return rmnet_map_ipv4_dl_csum_trailer(skb, csum_trailer, priv); |
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|
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if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) |
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return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer, priv); |
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|
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priv->stats.csum_err_invalid_ip_version++; |
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return -EPROTONOSUPPORT; |
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} |
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|
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static void rmnet_map_v4_checksum_uplink_packet(struct sk_buff *skb, |
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struct net_device *orig_dev) |
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{ |
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struct rmnet_priv *priv = netdev_priv(orig_dev); |
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struct rmnet_map_ul_csum_header *ul_header; |
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void *iphdr; |
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|
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ul_header = (struct rmnet_map_ul_csum_header *) |
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skb_push(skb, sizeof(struct rmnet_map_ul_csum_header)); |
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|
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if (unlikely(!(orig_dev->features & |
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(NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM)))) |
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goto sw_csum; |
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|
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if (skb->ip_summed != CHECKSUM_PARTIAL) |
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goto sw_csum; |
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|
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iphdr = (char *)ul_header + |
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sizeof(struct rmnet_map_ul_csum_header); |
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|
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if (skb->protocol == htons(ETH_P_IP)) { |
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rmnet_map_ipv4_ul_csum_header(iphdr, ul_header, skb); |
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priv->stats.csum_hw++; |
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return; |
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} |
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|
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if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) { |
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rmnet_map_ipv6_ul_csum_header(iphdr, ul_header, skb); |
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priv->stats.csum_hw++; |
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return; |
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} |
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|
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priv->stats.csum_err_invalid_ip_version++; |
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sw_csum: |
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memset(ul_header, 0, sizeof(*ul_header)); |
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|
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priv->stats.csum_sw++; |
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} |
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|
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/* Generates UL checksum meta info header for IPv4 and IPv6 over TCP and UDP |
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* packets that are supported for UL checksum offload. |
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*/ |
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void rmnet_map_checksum_uplink_packet(struct sk_buff *skb, |
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struct rmnet_port *port, |
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struct net_device *orig_dev, |
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int csum_type) |
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{ |
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switch (csum_type) { |
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case RMNET_FLAGS_EGRESS_MAP_CKSUMV4: |
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rmnet_map_v4_checksum_uplink_packet(skb, orig_dev); |
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break; |
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case RMNET_FLAGS_EGRESS_MAP_CKSUMV5: |
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rmnet_map_v5_checksum_uplink_packet(skb, port, orig_dev); |
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break; |
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default: |
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break; |
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} |
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} |
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|
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/* Process a MAPv5 packet header */ |
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int rmnet_map_process_next_hdr_packet(struct sk_buff *skb, |
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u16 len) |
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{ |
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struct rmnet_priv *priv = netdev_priv(skb->dev); |
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struct rmnet_map_v5_csum_header *next_hdr; |
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u8 nexthdr_type; |
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|
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next_hdr = (struct rmnet_map_v5_csum_header *)(skb->data + |
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sizeof(struct rmnet_map_header)); |
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|
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nexthdr_type = u8_get_bits(next_hdr->header_info, |
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MAPV5_HDRINFO_HDR_TYPE_FMASK); |
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|
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if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD) |
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return -EINVAL; |
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|
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if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) { |
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priv->stats.csum_sw++; |
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} else if (next_hdr->csum_info & MAPV5_CSUMINFO_VALID_FLAG) { |
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priv->stats.csum_ok++; |
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skb->ip_summed = CHECKSUM_UNNECESSARY; |
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} else { |
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priv->stats.csum_valid_unset++; |
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} |
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|
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/* Pull csum v5 header */ |
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skb_pull(skb, sizeof(*next_hdr)); |
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|
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return 0; |
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}
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