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 #include <net/pkt_cls.h> 20 21 #include <linux/tc_act/tc_skbmod.h> 22 #include <net/tc_act/tc_skbmod.h> 23 24 static unsigned int skbmod_net_id; 25 static struct tc_action_ops act_skbmod_ops; 26 27 #define MAX_EDIT_LEN ETH_HLEN 28 static int tcf_skbmod_act(struct sk_buff *skb, const struct tc_action *a, 29 struct tcf_result *res) 30 { 31 struct tcf_skbmod *d = to_skbmod(a); 32 int action; 33 struct tcf_skbmod_params *p; 34 u64 flags; 35 int err; 36 37 tcf_lastuse_update(&d->tcf_tm); 38 bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb); 39 40 /* XXX: if you are going to edit more fields beyond ethernet header 41 * (example when you add IP header replacement or vlan swap) 42 * then MAX_EDIT_LEN needs to change appropriately 43 */ 44 err = skb_ensure_writable(skb, MAX_EDIT_LEN); 45 if (unlikely(err)) /* best policy is to drop on the floor */ 46 goto drop; 47 48 action = READ_ONCE(d->tcf_action); 49 if (unlikely(action == TC_ACT_SHOT)) 50 goto drop; 51 52 p = rcu_dereference_bh(d->skbmod_p); 53 flags = p->flags; 54 if (flags & SKBMOD_F_DMAC) 55 ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst); 56 if (flags & SKBMOD_F_SMAC) 57 ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src); 58 if (flags & SKBMOD_F_ETYPE) 59 eth_hdr(skb)->h_proto = p->eth_type; 60 61 if (flags & SKBMOD_F_SWAPMAC) { 62 u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */ 63 /*XXX: I am sure we can come up with more efficient swapping*/ 64 ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest); 65 ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source); 66 ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr); 67 } 68 69 return action; 70 71 drop: 72 qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats)); 73 return TC_ACT_SHOT; 74 } 75 76 static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = { 77 [TCA_SKBMOD_PARMS] = { .len = sizeof(struct tc_skbmod) }, 78 [TCA_SKBMOD_DMAC] = { .len = ETH_ALEN }, 79 [TCA_SKBMOD_SMAC] = { .len = ETH_ALEN }, 80 [TCA_SKBMOD_ETYPE] = { .type = NLA_U16 }, 81 }; 82 83 static int tcf_skbmod_init(struct net *net, struct nlattr *nla, 84 struct nlattr *est, struct tc_action **a, 85 int ovr, int bind, bool rtnl_held, 86 struct tcf_proto *tp, 87 struct netlink_ext_ack *extack) 88 { 89 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 90 struct nlattr *tb[TCA_SKBMOD_MAX + 1]; 91 struct tcf_skbmod_params *p, *p_old; 92 struct tcf_chain *goto_ch = NULL; 93 struct tc_skbmod *parm; 94 struct tcf_skbmod *d; 95 bool exists = false; 96 u8 *daddr = NULL; 97 u8 *saddr = NULL; 98 u16 eth_type = 0; 99 u32 lflags = 0; 100 int ret = 0, err; 101 102 if (!nla) 103 return -EINVAL; 104 105 err = nla_parse_nested_deprecated(tb, TCA_SKBMOD_MAX, nla, 106 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 err = tcf_idr_check_alloc(tn, &parm->index, a, bind); 133 if (err < 0) 134 return err; 135 exists = err; 136 if (exists && bind) 137 return 0; 138 139 if (!lflags) { 140 if (exists) 141 tcf_idr_release(*a, bind); 142 else 143 tcf_idr_cleanup(tn, parm->index); 144 return -EINVAL; 145 } 146 147 if (!exists) { 148 ret = tcf_idr_create(tn, parm->index, est, a, 149 &act_skbmod_ops, bind, true); 150 if (ret) { 151 tcf_idr_cleanup(tn, parm->index); 152 return ret; 153 } 154 155 ret = ACT_P_CREATED; 156 } else if (!ovr) { 157 tcf_idr_release(*a, bind); 158 return -EEXIST; 159 } 160 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); 161 if (err < 0) 162 goto release_idr; 163 164 d = to_skbmod(*a); 165 166 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL); 167 if (unlikely(!p)) { 168 err = -ENOMEM; 169 goto put_chain; 170 } 171 172 p->flags = lflags; 173 174 if (ovr) 175 spin_lock_bh(&d->tcf_lock); 176 /* Protected by tcf_lock if overwriting existing action. */ 177 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); 178 p_old = rcu_dereference_protected(d->skbmod_p, 1); 179 180 if (lflags & SKBMOD_F_DMAC) 181 ether_addr_copy(p->eth_dst, daddr); 182 if (lflags & SKBMOD_F_SMAC) 183 ether_addr_copy(p->eth_src, saddr); 184 if (lflags & SKBMOD_F_ETYPE) 185 p->eth_type = htons(eth_type); 186 187 rcu_assign_pointer(d->skbmod_p, p); 188 if (ovr) 189 spin_unlock_bh(&d->tcf_lock); 190 191 if (p_old) 192 kfree_rcu(p_old, rcu); 193 if (goto_ch) 194 tcf_chain_put_by_act(goto_ch); 195 196 if (ret == ACT_P_CREATED) 197 tcf_idr_insert(tn, *a); 198 return ret; 199 put_chain: 200 if (goto_ch) 201 tcf_chain_put_by_act(goto_ch); 202 release_idr: 203 tcf_idr_release(*a, bind); 204 return err; 205 } 206 207 static void tcf_skbmod_cleanup(struct tc_action *a) 208 { 209 struct tcf_skbmod *d = to_skbmod(a); 210 struct tcf_skbmod_params *p; 211 212 p = rcu_dereference_protected(d->skbmod_p, 1); 213 if (p) 214 kfree_rcu(p, rcu); 215 } 216 217 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, 218 int bind, int ref) 219 { 220 struct tcf_skbmod *d = to_skbmod(a); 221 unsigned char *b = skb_tail_pointer(skb); 222 struct tcf_skbmod_params *p; 223 struct tc_skbmod opt = { 224 .index = d->tcf_index, 225 .refcnt = refcount_read(&d->tcf_refcnt) - ref, 226 .bindcnt = atomic_read(&d->tcf_bindcnt) - bind, 227 }; 228 struct tcf_t t; 229 230 spin_lock_bh(&d->tcf_lock); 231 opt.action = d->tcf_action; 232 p = rcu_dereference_protected(d->skbmod_p, 233 lockdep_is_held(&d->tcf_lock)); 234 opt.flags = p->flags; 235 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt)) 236 goto nla_put_failure; 237 if ((p->flags & SKBMOD_F_DMAC) && 238 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst)) 239 goto nla_put_failure; 240 if ((p->flags & SKBMOD_F_SMAC) && 241 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src)) 242 goto nla_put_failure; 243 if ((p->flags & SKBMOD_F_ETYPE) && 244 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type))) 245 goto nla_put_failure; 246 247 tcf_tm_dump(&t, &d->tcf_tm); 248 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD)) 249 goto nla_put_failure; 250 251 spin_unlock_bh(&d->tcf_lock); 252 return skb->len; 253 nla_put_failure: 254 spin_unlock_bh(&d->tcf_lock); 255 nlmsg_trim(skb, b); 256 return -1; 257 } 258 259 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb, 260 struct netlink_callback *cb, int type, 261 const struct tc_action_ops *ops, 262 struct netlink_ext_ack *extack) 263 { 264 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 265 266 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 267 } 268 269 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index) 270 { 271 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 272 273 return tcf_idr_search(tn, a, index); 274 } 275 276 static struct tc_action_ops act_skbmod_ops = { 277 .kind = "skbmod", 278 .id = TCA_ACT_SKBMOD, 279 .owner = THIS_MODULE, 280 .act = tcf_skbmod_act, 281 .dump = tcf_skbmod_dump, 282 .init = tcf_skbmod_init, 283 .cleanup = tcf_skbmod_cleanup, 284 .walk = tcf_skbmod_walker, 285 .lookup = tcf_skbmod_search, 286 .size = sizeof(struct tcf_skbmod), 287 }; 288 289 static __net_init int skbmod_init_net(struct net *net) 290 { 291 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 292 293 return tc_action_net_init(tn, &act_skbmod_ops); 294 } 295 296 static void __net_exit skbmod_exit_net(struct list_head *net_list) 297 { 298 tc_action_net_exit(net_list, skbmod_net_id); 299 } 300 301 static struct pernet_operations skbmod_net_ops = { 302 .init = skbmod_init_net, 303 .exit_batch = skbmod_exit_net, 304 .id = &skbmod_net_id, 305 .size = sizeof(struct tc_action_net), 306 }; 307 308 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>"); 309 MODULE_DESCRIPTION("SKB data mod-ing"); 310 MODULE_LICENSE("GPL"); 311 312 static int __init skbmod_init_module(void) 313 { 314 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops); 315 } 316 317 static void __exit skbmod_cleanup_module(void) 318 { 319 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops); 320 } 321 322 module_init(skbmod_init_module); 323 module_exit(skbmod_cleanup_module); 324