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