1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/sched/act_skbmod.c skb data modifier 4 * 5 * Copyright (c) 2016 Jamal Hadi Salim <jhs@mojatatu.com> 6 */ 7 8 #include <linux/module.h> 9 #include <linux/if_arp.h> 10 #include <linux/init.h> 11 #include <linux/kernel.h> 12 #include <linux/skbuff.h> 13 #include <linux/rtnetlink.h> 14 #include <net/inet_ecn.h> 15 #include <net/netlink.h> 16 #include <net/pkt_sched.h> 17 #include <net/pkt_cls.h> 18 19 #include <linux/tc_act/tc_skbmod.h> 20 #include <net/tc_act/tc_skbmod.h> 21 22 static unsigned int skbmod_net_id; 23 static struct tc_action_ops act_skbmod_ops; 24 25 static int tcf_skbmod_act(struct sk_buff *skb, const struct tc_action *a, 26 struct tcf_result *res) 27 { 28 struct tcf_skbmod *d = to_skbmod(a); 29 int action, max_edit_len, err; 30 struct tcf_skbmod_params *p; 31 u64 flags; 32 33 tcf_lastuse_update(&d->tcf_tm); 34 bstats_update(this_cpu_ptr(d->common.cpu_bstats), skb); 35 36 action = READ_ONCE(d->tcf_action); 37 if (unlikely(action == TC_ACT_SHOT)) 38 goto drop; 39 40 max_edit_len = skb_mac_header_len(skb); 41 p = rcu_dereference_bh(d->skbmod_p); 42 flags = p->flags; 43 44 /* tcf_skbmod_init() guarantees "flags" to be one of the following: 45 * 1. a combination of SKBMOD_F_{DMAC,SMAC,ETYPE} 46 * 2. SKBMOD_F_SWAPMAC 47 * 3. SKBMOD_F_ECN 48 * SKBMOD_F_ECN only works with IP packets; all other flags only work with Ethernet 49 * packets. 50 */ 51 if (flags == SKBMOD_F_ECN) { 52 switch (skb_protocol(skb, true)) { 53 case cpu_to_be16(ETH_P_IP): 54 case cpu_to_be16(ETH_P_IPV6): 55 max_edit_len += skb_network_header_len(skb); 56 break; 57 default: 58 goto out; 59 } 60 } else if (!skb->dev || skb->dev->type != ARPHRD_ETHER) { 61 goto out; 62 } 63 64 err = skb_ensure_writable(skb, max_edit_len); 65 if (unlikely(err)) /* best policy is to drop on the floor */ 66 goto drop; 67 68 if (flags & SKBMOD_F_DMAC) 69 ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst); 70 if (flags & SKBMOD_F_SMAC) 71 ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src); 72 if (flags & SKBMOD_F_ETYPE) 73 eth_hdr(skb)->h_proto = p->eth_type; 74 75 if (flags & SKBMOD_F_SWAPMAC) { 76 u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */ 77 /*XXX: I am sure we can come up with more efficient swapping*/ 78 ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest); 79 ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source); 80 ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr); 81 } 82 83 if (flags & SKBMOD_F_ECN) 84 INET_ECN_set_ce(skb); 85 86 out: 87 return action; 88 89 drop: 90 qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats)); 91 return TC_ACT_SHOT; 92 } 93 94 static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = { 95 [TCA_SKBMOD_PARMS] = { .len = sizeof(struct tc_skbmod) }, 96 [TCA_SKBMOD_DMAC] = { .len = ETH_ALEN }, 97 [TCA_SKBMOD_SMAC] = { .len = ETH_ALEN }, 98 [TCA_SKBMOD_ETYPE] = { .type = NLA_U16 }, 99 }; 100 101 static int tcf_skbmod_init(struct net *net, struct nlattr *nla, 102 struct nlattr *est, struct tc_action **a, 103 struct tcf_proto *tp, u32 flags, 104 struct netlink_ext_ack *extack) 105 { 106 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 107 bool ovr = flags & TCA_ACT_FLAGS_REPLACE; 108 bool bind = flags & TCA_ACT_FLAGS_BIND; 109 struct nlattr *tb[TCA_SKBMOD_MAX + 1]; 110 struct tcf_skbmod_params *p, *p_old; 111 struct tcf_chain *goto_ch = NULL; 112 struct tc_skbmod *parm; 113 u32 lflags = 0, index; 114 struct tcf_skbmod *d; 115 bool exists = false; 116 u8 *daddr = NULL; 117 u8 *saddr = NULL; 118 u16 eth_type = 0; 119 int ret = 0, err; 120 121 if (!nla) 122 return -EINVAL; 123 124 err = nla_parse_nested_deprecated(tb, TCA_SKBMOD_MAX, nla, 125 skbmod_policy, NULL); 126 if (err < 0) 127 return err; 128 129 if (!tb[TCA_SKBMOD_PARMS]) 130 return -EINVAL; 131 132 if (tb[TCA_SKBMOD_DMAC]) { 133 daddr = nla_data(tb[TCA_SKBMOD_DMAC]); 134 lflags |= SKBMOD_F_DMAC; 135 } 136 137 if (tb[TCA_SKBMOD_SMAC]) { 138 saddr = nla_data(tb[TCA_SKBMOD_SMAC]); 139 lflags |= SKBMOD_F_SMAC; 140 } 141 142 if (tb[TCA_SKBMOD_ETYPE]) { 143 eth_type = nla_get_u16(tb[TCA_SKBMOD_ETYPE]); 144 lflags |= SKBMOD_F_ETYPE; 145 } 146 147 parm = nla_data(tb[TCA_SKBMOD_PARMS]); 148 index = parm->index; 149 if (parm->flags & SKBMOD_F_SWAPMAC) 150 lflags = SKBMOD_F_SWAPMAC; 151 if (parm->flags & SKBMOD_F_ECN) 152 lflags = SKBMOD_F_ECN; 153 154 err = tcf_idr_check_alloc(tn, &index, a, bind); 155 if (err < 0) 156 return err; 157 exists = err; 158 if (exists && bind) 159 return 0; 160 161 if (!lflags) { 162 if (exists) 163 tcf_idr_release(*a, bind); 164 else 165 tcf_idr_cleanup(tn, index); 166 return -EINVAL; 167 } 168 169 if (!exists) { 170 ret = tcf_idr_create(tn, index, est, a, 171 &act_skbmod_ops, bind, true, 0); 172 if (ret) { 173 tcf_idr_cleanup(tn, index); 174 return ret; 175 } 176 177 ret = ACT_P_CREATED; 178 } else if (!ovr) { 179 tcf_idr_release(*a, bind); 180 return -EEXIST; 181 } 182 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); 183 if (err < 0) 184 goto release_idr; 185 186 d = to_skbmod(*a); 187 188 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL); 189 if (unlikely(!p)) { 190 err = -ENOMEM; 191 goto put_chain; 192 } 193 194 p->flags = lflags; 195 196 if (ovr) 197 spin_lock_bh(&d->tcf_lock); 198 /* Protected by tcf_lock if overwriting existing action. */ 199 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); 200 p_old = rcu_dereference_protected(d->skbmod_p, 1); 201 202 if (lflags & SKBMOD_F_DMAC) 203 ether_addr_copy(p->eth_dst, daddr); 204 if (lflags & SKBMOD_F_SMAC) 205 ether_addr_copy(p->eth_src, saddr); 206 if (lflags & SKBMOD_F_ETYPE) 207 p->eth_type = htons(eth_type); 208 209 rcu_assign_pointer(d->skbmod_p, p); 210 if (ovr) 211 spin_unlock_bh(&d->tcf_lock); 212 213 if (p_old) 214 kfree_rcu(p_old, rcu); 215 if (goto_ch) 216 tcf_chain_put_by_act(goto_ch); 217 218 return ret; 219 put_chain: 220 if (goto_ch) 221 tcf_chain_put_by_act(goto_ch); 222 release_idr: 223 tcf_idr_release(*a, bind); 224 return err; 225 } 226 227 static void tcf_skbmod_cleanup(struct tc_action *a) 228 { 229 struct tcf_skbmod *d = to_skbmod(a); 230 struct tcf_skbmod_params *p; 231 232 p = rcu_dereference_protected(d->skbmod_p, 1); 233 if (p) 234 kfree_rcu(p, rcu); 235 } 236 237 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, 238 int bind, int ref) 239 { 240 struct tcf_skbmod *d = to_skbmod(a); 241 unsigned char *b = skb_tail_pointer(skb); 242 struct tcf_skbmod_params *p; 243 struct tc_skbmod opt = { 244 .index = d->tcf_index, 245 .refcnt = refcount_read(&d->tcf_refcnt) - ref, 246 .bindcnt = atomic_read(&d->tcf_bindcnt) - bind, 247 }; 248 struct tcf_t t; 249 250 spin_lock_bh(&d->tcf_lock); 251 opt.action = d->tcf_action; 252 p = rcu_dereference_protected(d->skbmod_p, 253 lockdep_is_held(&d->tcf_lock)); 254 opt.flags = p->flags; 255 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt)) 256 goto nla_put_failure; 257 if ((p->flags & SKBMOD_F_DMAC) && 258 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst)) 259 goto nla_put_failure; 260 if ((p->flags & SKBMOD_F_SMAC) && 261 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src)) 262 goto nla_put_failure; 263 if ((p->flags & SKBMOD_F_ETYPE) && 264 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type))) 265 goto nla_put_failure; 266 267 tcf_tm_dump(&t, &d->tcf_tm); 268 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD)) 269 goto nla_put_failure; 270 271 spin_unlock_bh(&d->tcf_lock); 272 return skb->len; 273 nla_put_failure: 274 spin_unlock_bh(&d->tcf_lock); 275 nlmsg_trim(skb, b); 276 return -1; 277 } 278 279 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb, 280 struct netlink_callback *cb, int type, 281 const struct tc_action_ops *ops, 282 struct netlink_ext_ack *extack) 283 { 284 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 285 286 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 287 } 288 289 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index) 290 { 291 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 292 293 return tcf_idr_search(tn, a, index); 294 } 295 296 static struct tc_action_ops act_skbmod_ops = { 297 .kind = "skbmod", 298 .id = TCA_ACT_SKBMOD, 299 .owner = THIS_MODULE, 300 .act = tcf_skbmod_act, 301 .dump = tcf_skbmod_dump, 302 .init = tcf_skbmod_init, 303 .cleanup = tcf_skbmod_cleanup, 304 .walk = tcf_skbmod_walker, 305 .lookup = tcf_skbmod_search, 306 .size = sizeof(struct tcf_skbmod), 307 }; 308 309 static __net_init int skbmod_init_net(struct net *net) 310 { 311 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 312 313 return tc_action_net_init(net, tn, &act_skbmod_ops); 314 } 315 316 static void __net_exit skbmod_exit_net(struct list_head *net_list) 317 { 318 tc_action_net_exit(net_list, skbmod_net_id); 319 } 320 321 static struct pernet_operations skbmod_net_ops = { 322 .init = skbmod_init_net, 323 .exit_batch = skbmod_exit_net, 324 .id = &skbmod_net_id, 325 .size = sizeof(struct tc_action_net), 326 }; 327 328 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>"); 329 MODULE_DESCRIPTION("SKB data mod-ing"); 330 MODULE_LICENSE("GPL"); 331 332 static int __init skbmod_init_module(void) 333 { 334 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops); 335 } 336 337 static void __exit skbmod_cleanup_module(void) 338 { 339 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops); 340 } 341 342 module_init(skbmod_init_module); 343 module_exit(skbmod_cleanup_module); 344