1 /* 2 * net/sched/act_skbmod.c skb data modifier 3 * 4 * Copyright (c) 2016 Jamal Hadi Salim <jhs@mojatatu.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 */ 11 12 #include <linux/module.h> 13 #include <linux/init.h> 14 #include <linux/kernel.h> 15 #include <linux/skbuff.h> 16 #include <linux/rtnetlink.h> 17 #include <net/netlink.h> 18 #include <net/pkt_sched.h> 19 20 #include <linux/tc_act/tc_skbmod.h> 21 #include <net/tc_act/tc_skbmod.h> 22 23 #define SKBMOD_TAB_MASK 15 24 25 static unsigned int skbmod_net_id; 26 static struct tc_action_ops act_skbmod_ops; 27 28 #define MAX_EDIT_LEN ETH_HLEN 29 static int tcf_skbmod_run(struct sk_buff *skb, const struct tc_action *a, 30 struct tcf_result *res) 31 { 32 struct tcf_skbmod *d = to_skbmod(a); 33 int action; 34 struct tcf_skbmod_params *p; 35 u64 flags; 36 int err; 37 38 tcf_lastuse_update(&d->tcf_tm); 39 bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb); 40 41 /* XXX: if you are going to edit more fields beyond ethernet header 42 * (example when you add IP header replacement or vlan swap) 43 * then MAX_EDIT_LEN needs to change appropriately 44 */ 45 err = skb_ensure_writable(skb, MAX_EDIT_LEN); 46 if (unlikely(err)) { /* best policy is to drop on the floor */ 47 qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats)); 48 return TC_ACT_SHOT; 49 } 50 51 rcu_read_lock(); 52 action = READ_ONCE(d->tcf_action); 53 if (unlikely(action == TC_ACT_SHOT)) { 54 qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats)); 55 rcu_read_unlock(); 56 return action; 57 } 58 59 p = rcu_dereference(d->skbmod_p); 60 flags = p->flags; 61 if (flags & SKBMOD_F_DMAC) 62 ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst); 63 if (flags & SKBMOD_F_SMAC) 64 ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src); 65 if (flags & SKBMOD_F_ETYPE) 66 eth_hdr(skb)->h_proto = p->eth_type; 67 rcu_read_unlock(); 68 69 if (flags & SKBMOD_F_SWAPMAC) { 70 u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */ 71 /*XXX: I am sure we can come up with more efficient swapping*/ 72 ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest); 73 ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source); 74 ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr); 75 } 76 77 return action; 78 } 79 80 static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = { 81 [TCA_SKBMOD_PARMS] = { .len = sizeof(struct tc_skbmod) }, 82 [TCA_SKBMOD_DMAC] = { .len = ETH_ALEN }, 83 [TCA_SKBMOD_SMAC] = { .len = ETH_ALEN }, 84 [TCA_SKBMOD_ETYPE] = { .type = NLA_U16 }, 85 }; 86 87 static int tcf_skbmod_init(struct net *net, struct nlattr *nla, 88 struct nlattr *est, struct tc_action **a, 89 int ovr, int bind) 90 { 91 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 92 struct nlattr *tb[TCA_SKBMOD_MAX + 1]; 93 struct tcf_skbmod_params *p, *p_old; 94 struct tc_skbmod *parm; 95 struct tcf_skbmod *d; 96 bool exists = false; 97 u8 *daddr = NULL; 98 u8 *saddr = NULL; 99 u16 eth_type = 0; 100 u32 lflags = 0; 101 int ret = 0, err; 102 103 if (!nla) 104 return -EINVAL; 105 106 err = nla_parse_nested(tb, TCA_SKBMOD_MAX, nla, skbmod_policy, NULL); 107 if (err < 0) 108 return err; 109 110 if (!tb[TCA_SKBMOD_PARMS]) 111 return -EINVAL; 112 113 if (tb[TCA_SKBMOD_DMAC]) { 114 daddr = nla_data(tb[TCA_SKBMOD_DMAC]); 115 lflags |= SKBMOD_F_DMAC; 116 } 117 118 if (tb[TCA_SKBMOD_SMAC]) { 119 saddr = nla_data(tb[TCA_SKBMOD_SMAC]); 120 lflags |= SKBMOD_F_SMAC; 121 } 122 123 if (tb[TCA_SKBMOD_ETYPE]) { 124 eth_type = nla_get_u16(tb[TCA_SKBMOD_ETYPE]); 125 lflags |= SKBMOD_F_ETYPE; 126 } 127 128 parm = nla_data(tb[TCA_SKBMOD_PARMS]); 129 if (parm->flags & SKBMOD_F_SWAPMAC) 130 lflags = SKBMOD_F_SWAPMAC; 131 132 exists = tcf_hash_check(tn, parm->index, a, bind); 133 if (exists && bind) 134 return 0; 135 136 if (!lflags) 137 return -EINVAL; 138 139 if (!exists) { 140 ret = tcf_hash_create(tn, parm->index, est, a, 141 &act_skbmod_ops, bind, true); 142 if (ret) 143 return ret; 144 145 ret = ACT_P_CREATED; 146 } else { 147 tcf_hash_release(*a, bind); 148 if (!ovr) 149 return -EEXIST; 150 } 151 152 d = to_skbmod(*a); 153 154 ASSERT_RTNL(); 155 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL); 156 if (unlikely(!p)) { 157 if (ovr) 158 tcf_hash_release(*a, bind); 159 return -ENOMEM; 160 } 161 162 p->flags = lflags; 163 d->tcf_action = parm->action; 164 165 p_old = rtnl_dereference(d->skbmod_p); 166 167 if (ovr) 168 spin_lock_bh(&d->tcf_lock); 169 170 if (lflags & SKBMOD_F_DMAC) 171 ether_addr_copy(p->eth_dst, daddr); 172 if (lflags & SKBMOD_F_SMAC) 173 ether_addr_copy(p->eth_src, saddr); 174 if (lflags & SKBMOD_F_ETYPE) 175 p->eth_type = htons(eth_type); 176 177 rcu_assign_pointer(d->skbmod_p, p); 178 if (ovr) 179 spin_unlock_bh(&d->tcf_lock); 180 181 if (p_old) 182 kfree_rcu(p_old, rcu); 183 184 if (ret == ACT_P_CREATED) 185 tcf_hash_insert(tn, *a); 186 return ret; 187 } 188 189 static void tcf_skbmod_cleanup(struct tc_action *a, int bind) 190 { 191 struct tcf_skbmod *d = to_skbmod(a); 192 struct tcf_skbmod_params *p; 193 194 p = rcu_dereference_protected(d->skbmod_p, 1); 195 kfree_rcu(p, rcu); 196 } 197 198 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, 199 int bind, int ref) 200 { 201 struct tcf_skbmod *d = to_skbmod(a); 202 unsigned char *b = skb_tail_pointer(skb); 203 struct tcf_skbmod_params *p = rtnl_dereference(d->skbmod_p); 204 struct tc_skbmod opt = { 205 .index = d->tcf_index, 206 .refcnt = d->tcf_refcnt - ref, 207 .bindcnt = d->tcf_bindcnt - bind, 208 .action = d->tcf_action, 209 }; 210 struct tcf_t t; 211 212 opt.flags = p->flags; 213 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt)) 214 goto nla_put_failure; 215 if ((p->flags & SKBMOD_F_DMAC) && 216 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst)) 217 goto nla_put_failure; 218 if ((p->flags & SKBMOD_F_SMAC) && 219 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src)) 220 goto nla_put_failure; 221 if ((p->flags & SKBMOD_F_ETYPE) && 222 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type))) 223 goto nla_put_failure; 224 225 tcf_tm_dump(&t, &d->tcf_tm); 226 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD)) 227 goto nla_put_failure; 228 229 return skb->len; 230 nla_put_failure: 231 nlmsg_trim(skb, b); 232 return -1; 233 } 234 235 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb, 236 struct netlink_callback *cb, int type, 237 const struct tc_action_ops *ops) 238 { 239 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 240 241 return tcf_generic_walker(tn, skb, cb, type, ops); 242 } 243 244 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index) 245 { 246 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 247 248 return tcf_hash_search(tn, a, index); 249 } 250 251 static struct tc_action_ops act_skbmod_ops = { 252 .kind = "skbmod", 253 .type = TCA_ACT_SKBMOD, 254 .owner = THIS_MODULE, 255 .act = tcf_skbmod_run, 256 .dump = tcf_skbmod_dump, 257 .init = tcf_skbmod_init, 258 .cleanup = tcf_skbmod_cleanup, 259 .walk = tcf_skbmod_walker, 260 .lookup = tcf_skbmod_search, 261 .size = sizeof(struct tcf_skbmod), 262 }; 263 264 static __net_init int skbmod_init_net(struct net *net) 265 { 266 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 267 268 return tc_action_net_init(tn, &act_skbmod_ops, SKBMOD_TAB_MASK); 269 } 270 271 static void __net_exit skbmod_exit_net(struct net *net) 272 { 273 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 274 275 tc_action_net_exit(tn); 276 } 277 278 static struct pernet_operations skbmod_net_ops = { 279 .init = skbmod_init_net, 280 .exit = skbmod_exit_net, 281 .id = &skbmod_net_id, 282 .size = sizeof(struct tc_action_net), 283 }; 284 285 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>"); 286 MODULE_DESCRIPTION("SKB data mod-ing"); 287 MODULE_LICENSE("GPL"); 288 289 static int __init skbmod_init_module(void) 290 { 291 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops); 292 } 293 294 static void __exit skbmod_cleanup_module(void) 295 { 296 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops); 297 } 298 299 module_init(skbmod_init_module); 300 module_exit(skbmod_cleanup_module); 301