1 // SPDX-License-Identifier: GPL-2.0-or-later 2 #include <linux/skbuff.h> 3 #include <linux/sctp.h> 4 #include <net/gso.h> 5 #include <net/gro.h> 6 7 /** 8 * skb_eth_gso_segment - segmentation handler for ethernet protocols. 9 * @skb: buffer to segment 10 * @features: features for the output path (see dev->features) 11 * @type: Ethernet Protocol ID 12 */ 13 struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb, 14 netdev_features_t features, __be16 type) 15 { 16 struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT); 17 struct packet_offload *ptype; 18 19 rcu_read_lock(); 20 list_for_each_entry_rcu(ptype, &net_hotdata.offload_base, list) { 21 if (ptype->type == type && ptype->callbacks.gso_segment) { 22 segs = ptype->callbacks.gso_segment(skb, features); 23 break; 24 } 25 } 26 rcu_read_unlock(); 27 28 return segs; 29 } 30 EXPORT_SYMBOL(skb_eth_gso_segment); 31 32 /** 33 * skb_mac_gso_segment - mac layer segmentation handler. 34 * @skb: buffer to segment 35 * @features: features for the output path (see dev->features) 36 */ 37 struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb, 38 netdev_features_t features) 39 { 40 struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT); 41 struct packet_offload *ptype; 42 int vlan_depth = skb->mac_len; 43 __be16 type = skb_network_protocol(skb, &vlan_depth); 44 45 if (unlikely(!type)) 46 return ERR_PTR(-EINVAL); 47 48 __skb_pull(skb, vlan_depth); 49 50 rcu_read_lock(); 51 list_for_each_entry_rcu(ptype, &net_hotdata.offload_base, list) { 52 if (ptype->type == type && ptype->callbacks.gso_segment) { 53 segs = ptype->callbacks.gso_segment(skb, features); 54 break; 55 } 56 } 57 rcu_read_unlock(); 58 59 __skb_push(skb, skb->data - skb_mac_header(skb)); 60 61 return segs; 62 } 63 EXPORT_SYMBOL(skb_mac_gso_segment); 64 /* openvswitch calls this on rx path, so we need a different check. 65 */ 66 static bool skb_needs_check(const struct sk_buff *skb, bool tx_path) 67 { 68 if (tx_path) 69 return skb->ip_summed != CHECKSUM_PARTIAL && 70 skb->ip_summed != CHECKSUM_UNNECESSARY; 71 72 return skb->ip_summed == CHECKSUM_NONE; 73 } 74 75 /** 76 * __skb_gso_segment - Perform segmentation on skb. 77 * @skb: buffer to segment 78 * @features: features for the output path (see dev->features) 79 * @tx_path: whether it is called in TX path 80 * 81 * This function segments the given skb and returns a list of segments. 82 * 83 * It may return NULL if the skb requires no segmentation. This is 84 * only possible when GSO is used for verifying header integrity. 85 * 86 * Segmentation preserves SKB_GSO_CB_OFFSET bytes of previous skb cb. 87 */ 88 struct sk_buff *__skb_gso_segment(struct sk_buff *skb, 89 netdev_features_t features, bool tx_path) 90 { 91 struct sk_buff *segs; 92 93 if (unlikely(skb_needs_check(skb, tx_path))) { 94 int err; 95 96 /* We're going to init ->check field in TCP or UDP header */ 97 err = skb_cow_head(skb, 0); 98 if (err < 0) 99 return ERR_PTR(err); 100 } 101 102 /* Only report GSO partial support if it will enable us to 103 * support segmentation on this frame without needing additional 104 * work. 105 */ 106 if (features & NETIF_F_GSO_PARTIAL) { 107 netdev_features_t partial_features = NETIF_F_GSO_ROBUST; 108 struct net_device *dev = skb->dev; 109 110 partial_features |= dev->features & dev->gso_partial_features; 111 if (!skb_gso_ok(skb, features | partial_features)) 112 features &= ~NETIF_F_GSO_PARTIAL; 113 } 114 115 BUILD_BUG_ON(SKB_GSO_CB_OFFSET + 116 sizeof(*SKB_GSO_CB(skb)) > sizeof(skb->cb)); 117 118 SKB_GSO_CB(skb)->mac_offset = skb_headroom(skb); 119 SKB_GSO_CB(skb)->encap_level = 0; 120 121 skb_reset_mac_header(skb); 122 skb_reset_mac_len(skb); 123 124 segs = skb_mac_gso_segment(skb, features); 125 126 if (segs != skb && unlikely(skb_needs_check(skb, tx_path) && !IS_ERR(segs))) 127 skb_warn_bad_offload(skb); 128 129 return segs; 130 } 131 EXPORT_SYMBOL(__skb_gso_segment); 132 133 /** 134 * skb_gso_transport_seglen - Return length of individual segments of a gso packet 135 * 136 * @skb: GSO skb 137 * 138 * skb_gso_transport_seglen is used to determine the real size of the 139 * individual segments, including Layer4 headers (TCP/UDP). 140 * 141 * The MAC/L2 or network (IP, IPv6) headers are not accounted for. 142 */ 143 static unsigned int skb_gso_transport_seglen(const struct sk_buff *skb) 144 { 145 const struct skb_shared_info *shinfo = skb_shinfo(skb); 146 unsigned int thlen = 0; 147 148 if (skb->encapsulation) { 149 thlen = skb_inner_transport_header(skb) - 150 skb_transport_header(skb); 151 152 if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) 153 thlen += inner_tcp_hdrlen(skb); 154 } else if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) { 155 thlen = tcp_hdrlen(skb); 156 } else if (unlikely(skb_is_gso_sctp(skb))) { 157 thlen = sizeof(struct sctphdr); 158 } else if (shinfo->gso_type & SKB_GSO_UDP_L4) { 159 thlen = sizeof(struct udphdr); 160 } 161 /* UFO sets gso_size to the size of the fragmentation 162 * payload, i.e. the size of the L4 (UDP) header is already 163 * accounted for. 164 */ 165 return thlen + shinfo->gso_size; 166 } 167 168 /** 169 * skb_gso_network_seglen - Return length of individual segments of a gso packet 170 * 171 * @skb: GSO skb 172 * 173 * skb_gso_network_seglen is used to determine the real size of the 174 * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP). 175 * 176 * The MAC/L2 header is not accounted for. 177 */ 178 static unsigned int skb_gso_network_seglen(const struct sk_buff *skb) 179 { 180 unsigned int hdr_len = skb_transport_header(skb) - 181 skb_network_header(skb); 182 183 return hdr_len + skb_gso_transport_seglen(skb); 184 } 185 186 /** 187 * skb_gso_mac_seglen - Return length of individual segments of a gso packet 188 * 189 * @skb: GSO skb 190 * 191 * skb_gso_mac_seglen is used to determine the real size of the 192 * individual segments, including MAC/L2, Layer3 (IP, IPv6) and L4 193 * headers (TCP/UDP). 194 */ 195 static unsigned int skb_gso_mac_seglen(const struct sk_buff *skb) 196 { 197 unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb); 198 199 return hdr_len + skb_gso_transport_seglen(skb); 200 } 201 202 /** 203 * skb_gso_size_check - check the skb size, considering GSO_BY_FRAGS 204 * 205 * There are a couple of instances where we have a GSO skb, and we 206 * want to determine what size it would be after it is segmented. 207 * 208 * We might want to check: 209 * - L3+L4+payload size (e.g. IP forwarding) 210 * - L2+L3+L4+payload size (e.g. sanity check before passing to driver) 211 * 212 * This is a helper to do that correctly considering GSO_BY_FRAGS. 213 * 214 * @skb: GSO skb 215 * 216 * @seg_len: The segmented length (from skb_gso_*_seglen). In the 217 * GSO_BY_FRAGS case this will be [header sizes + GSO_BY_FRAGS]. 218 * 219 * @max_len: The maximum permissible length. 220 * 221 * Returns true if the segmented length <= max length. 222 */ 223 static inline bool skb_gso_size_check(const struct sk_buff *skb, 224 unsigned int seg_len, 225 unsigned int max_len) { 226 const struct skb_shared_info *shinfo = skb_shinfo(skb); 227 const struct sk_buff *iter; 228 229 if (shinfo->gso_size != GSO_BY_FRAGS) 230 return seg_len <= max_len; 231 232 /* Undo this so we can re-use header sizes */ 233 seg_len -= GSO_BY_FRAGS; 234 235 skb_walk_frags(skb, iter) { 236 if (seg_len + skb_headlen(iter) > max_len) 237 return false; 238 } 239 240 return true; 241 } 242 243 /** 244 * skb_gso_validate_network_len - Will a split GSO skb fit into a given MTU? 245 * 246 * @skb: GSO skb 247 * @mtu: MTU to validate against 248 * 249 * skb_gso_validate_network_len validates if a given skb will fit a 250 * wanted MTU once split. It considers L3 headers, L4 headers, and the 251 * payload. 252 */ 253 bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu) 254 { 255 return skb_gso_size_check(skb, skb_gso_network_seglen(skb), mtu); 256 } 257 EXPORT_SYMBOL_GPL(skb_gso_validate_network_len); 258 259 /** 260 * skb_gso_validate_mac_len - Will a split GSO skb fit in a given length? 261 * 262 * @skb: GSO skb 263 * @len: length to validate against 264 * 265 * skb_gso_validate_mac_len validates if a given skb will fit a wanted 266 * length once split, including L2, L3 and L4 headers and the payload. 267 */ 268 bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len) 269 { 270 return skb_gso_size_check(skb, skb_gso_mac_seglen(skb), len); 271 } 272 EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len); 273 274