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