1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * IPv6 library code, needed by static components when full IPv6 support is 4 * not configured or static. These functions are needed by GSO/GRO implementation. 5 */ 6 #include <linux/export.h> 7 #include <net/ip.h> 8 #include <net/ipv6.h> 9 #include <net/ip6_fib.h> 10 #include <net/addrconf.h> 11 #include <net/secure_seq.h> 12 #include <linux/netfilter.h> 13 14 static u32 __ipv6_select_ident(struct net *net, 15 const struct in6_addr *dst, 16 const struct in6_addr *src) 17 { 18 const struct { 19 struct in6_addr dst; 20 struct in6_addr src; 21 } __aligned(SIPHASH_ALIGNMENT) combined = { 22 .dst = *dst, 23 .src = *src, 24 }; 25 u32 hash, id; 26 27 /* Note the following code is not safe, but this is okay. */ 28 if (unlikely(siphash_key_is_zero(&net->ipv4.ip_id_key))) 29 get_random_bytes(&net->ipv4.ip_id_key, 30 sizeof(net->ipv4.ip_id_key)); 31 32 hash = siphash(&combined, sizeof(combined), &net->ipv4.ip_id_key); 33 34 /* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve, 35 * set the hight order instead thus minimizing possible future 36 * collisions. 37 */ 38 id = ip_idents_reserve(hash, 1); 39 if (unlikely(!id)) 40 id = 1 << 31; 41 42 return id; 43 } 44 45 /* This function exists only for tap drivers that must support broken 46 * clients requesting UFO without specifying an IPv6 fragment ID. 47 * 48 * This is similar to ipv6_select_ident() but we use an independent hash 49 * seed to limit information leakage. 50 * 51 * The network header must be set before calling this. 52 */ 53 __be32 ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb) 54 { 55 struct in6_addr buf[2]; 56 struct in6_addr *addrs; 57 u32 id; 58 59 addrs = skb_header_pointer(skb, 60 skb_network_offset(skb) + 61 offsetof(struct ipv6hdr, saddr), 62 sizeof(buf), buf); 63 if (!addrs) 64 return 0; 65 66 id = __ipv6_select_ident(net, &addrs[1], &addrs[0]); 67 return htonl(id); 68 } 69 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident); 70 71 __be32 ipv6_select_ident(struct net *net, 72 const struct in6_addr *daddr, 73 const struct in6_addr *saddr) 74 { 75 u32 id; 76 77 id = __ipv6_select_ident(net, daddr, saddr); 78 return htonl(id); 79 } 80 EXPORT_SYMBOL(ipv6_select_ident); 81 82 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr) 83 { 84 unsigned int offset = sizeof(struct ipv6hdr); 85 unsigned int packet_len = skb_tail_pointer(skb) - 86 skb_network_header(skb); 87 int found_rhdr = 0; 88 *nexthdr = &ipv6_hdr(skb)->nexthdr; 89 90 while (offset <= packet_len) { 91 struct ipv6_opt_hdr *exthdr; 92 93 switch (**nexthdr) { 94 95 case NEXTHDR_HOP: 96 break; 97 case NEXTHDR_ROUTING: 98 found_rhdr = 1; 99 break; 100 case NEXTHDR_DEST: 101 #if IS_ENABLED(CONFIG_IPV6_MIP6) 102 if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) 103 break; 104 #endif 105 if (found_rhdr) 106 return offset; 107 break; 108 default: 109 return offset; 110 } 111 112 if (offset + sizeof(struct ipv6_opt_hdr) > packet_len) 113 return -EINVAL; 114 115 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) + 116 offset); 117 offset += ipv6_optlen(exthdr); 118 if (offset > IPV6_MAXPLEN) 119 return -EINVAL; 120 *nexthdr = &exthdr->nexthdr; 121 } 122 123 return -EINVAL; 124 } 125 EXPORT_SYMBOL(ip6_find_1stfragopt); 126 127 #if IS_ENABLED(CONFIG_IPV6) 128 int ip6_dst_hoplimit(struct dst_entry *dst) 129 { 130 int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT); 131 if (hoplimit == 0) { 132 struct net_device *dev = dst->dev; 133 struct inet6_dev *idev; 134 135 rcu_read_lock(); 136 idev = __in6_dev_get(dev); 137 if (idev) 138 hoplimit = idev->cnf.hop_limit; 139 else 140 hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit; 141 rcu_read_unlock(); 142 } 143 return hoplimit; 144 } 145 EXPORT_SYMBOL(ip6_dst_hoplimit); 146 #endif 147 148 int __ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb) 149 { 150 int len; 151 152 len = skb->len - sizeof(struct ipv6hdr); 153 if (len > IPV6_MAXPLEN) 154 len = 0; 155 ipv6_hdr(skb)->payload_len = htons(len); 156 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); 157 158 /* if egress device is enslaved to an L3 master device pass the 159 * skb to its handler for processing 160 */ 161 skb = l3mdev_ip6_out(sk, skb); 162 if (unlikely(!skb)) 163 return 0; 164 165 skb->protocol = htons(ETH_P_IPV6); 166 167 return nf_hook(NFPROTO_IPV6, NF_INET_LOCAL_OUT, 168 net, sk, skb, NULL, skb_dst(skb)->dev, 169 dst_output); 170 } 171 EXPORT_SYMBOL_GPL(__ip6_local_out); 172 173 int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb) 174 { 175 int err; 176 177 err = __ip6_local_out(net, sk, skb); 178 if (likely(err == 1)) 179 err = dst_output(net, sk, skb); 180 181 return err; 182 } 183 EXPORT_SYMBOL_GPL(ip6_local_out); 184