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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * IPV4 GSO/GRO offload support
0004  * Linux INET implementation
0005  *
0006  * Copyright (C) 2016 secunet Security Networks AG
0007  * Author: Steffen Klassert <steffen.klassert@secunet.com>
0008  *
0009  * ESP GRO support
0010  */
0011 
0012 #include <linux/skbuff.h>
0013 #include <linux/init.h>
0014 #include <net/protocol.h>
0015 #include <crypto/aead.h>
0016 #include <crypto/authenc.h>
0017 #include <linux/err.h>
0018 #include <linux/module.h>
0019 #include <net/gro.h>
0020 #include <net/ip.h>
0021 #include <net/xfrm.h>
0022 #include <net/esp.h>
0023 #include <linux/scatterlist.h>
0024 #include <linux/kernel.h>
0025 #include <linux/slab.h>
0026 #include <linux/spinlock.h>
0027 #include <net/udp.h>
0028 
0029 static struct sk_buff *esp4_gro_receive(struct list_head *head,
0030                     struct sk_buff *skb)
0031 {
0032     int offset = skb_gro_offset(skb);
0033     struct xfrm_offload *xo;
0034     struct xfrm_state *x;
0035     __be32 seq;
0036     __be32 spi;
0037 
0038     if (!pskb_pull(skb, offset))
0039         return NULL;
0040 
0041     if (xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq) != 0)
0042         goto out;
0043 
0044     xo = xfrm_offload(skb);
0045     if (!xo || !(xo->flags & CRYPTO_DONE)) {
0046         struct sec_path *sp = secpath_set(skb);
0047 
0048         if (!sp)
0049             goto out;
0050 
0051         if (sp->len == XFRM_MAX_DEPTH)
0052             goto out_reset;
0053 
0054         x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
0055                       (xfrm_address_t *)&ip_hdr(skb)->daddr,
0056                       spi, IPPROTO_ESP, AF_INET);
0057         if (!x)
0058             goto out_reset;
0059 
0060         skb->mark = xfrm_smark_get(skb->mark, x);
0061 
0062         sp->xvec[sp->len++] = x;
0063         sp->olen++;
0064 
0065         xo = xfrm_offload(skb);
0066         if (!xo)
0067             goto out_reset;
0068     }
0069 
0070     xo->flags |= XFRM_GRO;
0071 
0072     XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
0073     XFRM_SPI_SKB_CB(skb)->family = AF_INET;
0074     XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
0075     XFRM_SPI_SKB_CB(skb)->seq = seq;
0076 
0077     /* We don't need to handle errors from xfrm_input, it does all
0078      * the error handling and frees the resources on error. */
0079     xfrm_input(skb, IPPROTO_ESP, spi, -2);
0080 
0081     return ERR_PTR(-EINPROGRESS);
0082 out_reset:
0083     secpath_reset(skb);
0084 out:
0085     skb_push(skb, offset);
0086     NAPI_GRO_CB(skb)->same_flow = 0;
0087     NAPI_GRO_CB(skb)->flush = 1;
0088 
0089     return NULL;
0090 }
0091 
0092 static void esp4_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
0093 {
0094     struct ip_esp_hdr *esph;
0095     struct iphdr *iph = ip_hdr(skb);
0096     struct xfrm_offload *xo = xfrm_offload(skb);
0097     int proto = iph->protocol;
0098 
0099     skb_push(skb, -skb_network_offset(skb));
0100     esph = ip_esp_hdr(skb);
0101     *skb_mac_header(skb) = IPPROTO_ESP;
0102 
0103     esph->spi = x->id.spi;
0104     esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
0105 
0106     xo->proto = proto;
0107 }
0108 
0109 static struct sk_buff *xfrm4_tunnel_gso_segment(struct xfrm_state *x,
0110                         struct sk_buff *skb,
0111                         netdev_features_t features)
0112 {
0113     return skb_eth_gso_segment(skb, features, htons(ETH_P_IP));
0114 }
0115 
0116 static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
0117                            struct sk_buff *skb,
0118                            netdev_features_t features)
0119 {
0120     const struct net_offload *ops;
0121     struct sk_buff *segs = ERR_PTR(-EINVAL);
0122     struct xfrm_offload *xo = xfrm_offload(skb);
0123 
0124     skb->transport_header += x->props.header_len;
0125     ops = rcu_dereference(inet_offloads[xo->proto]);
0126     if (likely(ops && ops->callbacks.gso_segment))
0127         segs = ops->callbacks.gso_segment(skb, features);
0128 
0129     return segs;
0130 }
0131 
0132 static struct sk_buff *xfrm4_beet_gso_segment(struct xfrm_state *x,
0133                           struct sk_buff *skb,
0134                           netdev_features_t features)
0135 {
0136     struct xfrm_offload *xo = xfrm_offload(skb);
0137     struct sk_buff *segs = ERR_PTR(-EINVAL);
0138     const struct net_offload *ops;
0139     u8 proto = xo->proto;
0140 
0141     skb->transport_header += x->props.header_len;
0142 
0143     if (x->sel.family != AF_INET6) {
0144         if (proto == IPPROTO_BEETPH) {
0145             struct ip_beet_phdr *ph =
0146                 (struct ip_beet_phdr *)skb->data;
0147 
0148             skb->transport_header += ph->hdrlen * 8;
0149             proto = ph->nexthdr;
0150         } else {
0151             skb->transport_header -= IPV4_BEET_PHMAXLEN;
0152         }
0153     } else {
0154         __be16 frag;
0155 
0156         skb->transport_header +=
0157             ipv6_skip_exthdr(skb, 0, &proto, &frag);
0158         if (proto == IPPROTO_TCP)
0159             skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
0160     }
0161 
0162     if (proto == IPPROTO_IPV6)
0163         skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
0164 
0165     __skb_pull(skb, skb_transport_offset(skb));
0166     ops = rcu_dereference(inet_offloads[proto]);
0167     if (likely(ops && ops->callbacks.gso_segment))
0168         segs = ops->callbacks.gso_segment(skb, features);
0169 
0170     return segs;
0171 }
0172 
0173 static struct sk_buff *xfrm4_outer_mode_gso_segment(struct xfrm_state *x,
0174                             struct sk_buff *skb,
0175                             netdev_features_t features)
0176 {
0177     switch (x->outer_mode.encap) {
0178     case XFRM_MODE_TUNNEL:
0179         return xfrm4_tunnel_gso_segment(x, skb, features);
0180     case XFRM_MODE_TRANSPORT:
0181         return xfrm4_transport_gso_segment(x, skb, features);
0182     case XFRM_MODE_BEET:
0183         return xfrm4_beet_gso_segment(x, skb, features);
0184     }
0185 
0186     return ERR_PTR(-EOPNOTSUPP);
0187 }
0188 
0189 static struct sk_buff *esp4_gso_segment(struct sk_buff *skb,
0190                         netdev_features_t features)
0191 {
0192     struct xfrm_state *x;
0193     struct ip_esp_hdr *esph;
0194     struct crypto_aead *aead;
0195     netdev_features_t esp_features = features;
0196     struct xfrm_offload *xo = xfrm_offload(skb);
0197     struct sec_path *sp;
0198 
0199     if (!xo)
0200         return ERR_PTR(-EINVAL);
0201 
0202     if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP))
0203         return ERR_PTR(-EINVAL);
0204 
0205     sp = skb_sec_path(skb);
0206     x = sp->xvec[sp->len - 1];
0207     aead = x->data;
0208     esph = ip_esp_hdr(skb);
0209 
0210     if (esph->spi != x->id.spi)
0211         return ERR_PTR(-EINVAL);
0212 
0213     if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
0214         return ERR_PTR(-EINVAL);
0215 
0216     __skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
0217 
0218     skb->encap_hdr_csum = 1;
0219 
0220     if ((!(skb->dev->gso_partial_features & NETIF_F_HW_ESP) &&
0221          !(features & NETIF_F_HW_ESP)) || x->xso.dev != skb->dev)
0222         esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK |
0223                         NETIF_F_SCTP_CRC);
0224     else if (!(features & NETIF_F_HW_ESP_TX_CSUM) &&
0225          !(skb->dev->gso_partial_features & NETIF_F_HW_ESP_TX_CSUM))
0226         esp_features = features & ~(NETIF_F_CSUM_MASK |
0227                         NETIF_F_SCTP_CRC);
0228 
0229     xo->flags |= XFRM_GSO_SEGMENT;
0230 
0231     return xfrm4_outer_mode_gso_segment(x, skb, esp_features);
0232 }
0233 
0234 static int esp_input_tail(struct xfrm_state *x, struct sk_buff *skb)
0235 {
0236     struct crypto_aead *aead = x->data;
0237     struct xfrm_offload *xo = xfrm_offload(skb);
0238 
0239     if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
0240         return -EINVAL;
0241 
0242     if (!(xo->flags & CRYPTO_DONE))
0243         skb->ip_summed = CHECKSUM_NONE;
0244 
0245     return esp_input_done2(skb, 0);
0246 }
0247 
0248 static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_t features)
0249 {
0250     int err;
0251     int alen;
0252     int blksize;
0253     struct xfrm_offload *xo;
0254     struct ip_esp_hdr *esph;
0255     struct crypto_aead *aead;
0256     struct esp_info esp;
0257     bool hw_offload = true;
0258     __u32 seq;
0259 
0260     esp.inplace = true;
0261 
0262     xo = xfrm_offload(skb);
0263 
0264     if (!xo)
0265         return -EINVAL;
0266 
0267     if ((!(features & NETIF_F_HW_ESP) &&
0268          !(skb->dev->gso_partial_features & NETIF_F_HW_ESP)) ||
0269         x->xso.dev != skb->dev) {
0270         xo->flags |= CRYPTO_FALLBACK;
0271         hw_offload = false;
0272     }
0273 
0274     esp.proto = xo->proto;
0275 
0276     /* skb is pure payload to encrypt */
0277 
0278     aead = x->data;
0279     alen = crypto_aead_authsize(aead);
0280 
0281     esp.tfclen = 0;
0282     /* XXX: Add support for tfc padding here. */
0283 
0284     blksize = ALIGN(crypto_aead_blocksize(aead), 4);
0285     esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
0286     esp.plen = esp.clen - skb->len - esp.tfclen;
0287     esp.tailen = esp.tfclen + esp.plen + alen;
0288 
0289     esp.esph = ip_esp_hdr(skb);
0290 
0291 
0292     if (!hw_offload || !skb_is_gso(skb)) {
0293         esp.nfrags = esp_output_head(x, skb, &esp);
0294         if (esp.nfrags < 0)
0295             return esp.nfrags;
0296     }
0297 
0298     seq = xo->seq.low;
0299 
0300     esph = esp.esph;
0301     esph->spi = x->id.spi;
0302 
0303     skb_push(skb, -skb_network_offset(skb));
0304 
0305     if (xo->flags & XFRM_GSO_SEGMENT) {
0306         esph->seq_no = htonl(seq);
0307 
0308         if (!skb_is_gso(skb))
0309             xo->seq.low++;
0310         else
0311             xo->seq.low += skb_shinfo(skb)->gso_segs;
0312     }
0313 
0314     esp.seqno = cpu_to_be64(seq + ((u64)xo->seq.hi << 32));
0315 
0316     ip_hdr(skb)->tot_len = htons(skb->len);
0317     ip_send_check(ip_hdr(skb));
0318 
0319     if (hw_offload) {
0320         if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
0321             return -ENOMEM;
0322 
0323         xo = xfrm_offload(skb);
0324         if (!xo)
0325             return -EINVAL;
0326 
0327         xo->flags |= XFRM_XMIT;
0328         return 0;
0329     }
0330 
0331     err = esp_output_tail(x, skb, &esp);
0332     if (err)
0333         return err;
0334 
0335     secpath_reset(skb);
0336 
0337     return 0;
0338 }
0339 
0340 static const struct net_offload esp4_offload = {
0341     .callbacks = {
0342         .gro_receive = esp4_gro_receive,
0343         .gso_segment = esp4_gso_segment,
0344     },
0345 };
0346 
0347 static const struct xfrm_type_offload esp_type_offload = {
0348     .owner      = THIS_MODULE,
0349     .proto          = IPPROTO_ESP,
0350     .input_tail = esp_input_tail,
0351     .xmit       = esp_xmit,
0352     .encap      = esp4_gso_encap,
0353 };
0354 
0355 static int __init esp4_offload_init(void)
0356 {
0357     if (xfrm_register_type_offload(&esp_type_offload, AF_INET) < 0) {
0358         pr_info("%s: can't add xfrm type offload\n", __func__);
0359         return -EAGAIN;
0360     }
0361 
0362     return inet_add_offload(&esp4_offload, IPPROTO_ESP);
0363 }
0364 
0365 static void __exit esp4_offload_exit(void)
0366 {
0367     xfrm_unregister_type_offload(&esp_type_offload, AF_INET);
0368     inet_del_offload(&esp4_offload, IPPROTO_ESP);
0369 }
0370 
0371 module_init(esp4_offload_init);
0372 module_exit(esp4_offload_exit);
0373 MODULE_LICENSE("GPL");
0374 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
0375 MODULE_ALIAS_XFRM_OFFLOAD_TYPE(AF_INET, XFRM_PROTO_ESP);
0376 MODULE_DESCRIPTION("IPV4 GSO/GRO offload support");
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