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(tb, TCA_SKBMOD_MAX, nla, skbmod_policy, NULL); 106 if (err < 0) 107 return err; 108 109 if (!tb[TCA_SKBMOD_PARMS]) 110 return -EINVAL; 111 112 if (tb[TCA_SKBMOD_DMAC]) { 113 daddr = nla_data(tb[TCA_SKBMOD_DMAC]); 114 lflags |= SKBMOD_F_DMAC; 115 } 116 117 if (tb[TCA_SKBMOD_SMAC]) { 118 saddr = nla_data(tb[TCA_SKBMOD_SMAC]); 119 lflags |= SKBMOD_F_SMAC; 120 } 121 122 if (tb[TCA_SKBMOD_ETYPE]) { 123 eth_type = nla_get_u16(tb[TCA_SKBMOD_ETYPE]); 124 lflags |= SKBMOD_F_ETYPE; 125 } 126 127 parm = nla_data(tb[TCA_SKBMOD_PARMS]); 128 if (parm->flags & SKBMOD_F_SWAPMAC) 129 lflags = SKBMOD_F_SWAPMAC; 130 131 err = tcf_idr_check_alloc(tn, &parm->index, a, bind); 132 if (err < 0) 133 return err; 134 exists = err; 135 if (exists && bind) 136 return 0; 137 138 if (!lflags) { 139 if (exists) 140 tcf_idr_release(*a, bind); 141 else 142 tcf_idr_cleanup(tn, parm->index); 143 return -EINVAL; 144 } 145 146 if (!exists) { 147 ret = tcf_idr_create(tn, parm->index, est, a, 148 &act_skbmod_ops, bind, true); 149 if (ret) { 150 tcf_idr_cleanup(tn, parm->index); 151 return ret; 152 } 153 154 ret = ACT_P_CREATED; 155 } else if (!ovr) { 156 tcf_idr_release(*a, bind); 157 return -EEXIST; 158 } 159 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); 160 if (err < 0) 161 goto release_idr; 162 163 d = to_skbmod(*a); 164 165 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL); 166 if (unlikely(!p)) { 167 err = -ENOMEM; 168 goto put_chain; 169 } 170 171 p->flags = lflags; 172 173 if (ovr) 174 spin_lock_bh(&d->tcf_lock); 175 /* Protected by tcf_lock if overwriting existing action. */ 176 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); 177 p_old = rcu_dereference_protected(d->skbmod_p, 1); 178 179 if (lflags & SKBMOD_F_DMAC) 180 ether_addr_copy(p->eth_dst, daddr); 181 if (lflags & SKBMOD_F_SMAC) 182 ether_addr_copy(p->eth_src, saddr); 183 if (lflags & SKBMOD_F_ETYPE) 184 p->eth_type = htons(eth_type); 185 186 rcu_assign_pointer(d->skbmod_p, p); 187 if (ovr) 188 spin_unlock_bh(&d->tcf_lock); 189 190 if (p_old) 191 kfree_rcu(p_old, rcu); 192 if (goto_ch) 193 tcf_chain_put_by_act(goto_ch); 194 195 if (ret == ACT_P_CREATED) 196 tcf_idr_insert(tn, *a); 197 return ret; 198 put_chain: 199 if (goto_ch) 200 tcf_chain_put_by_act(goto_ch); 201 release_idr: 202 tcf_idr_release(*a, bind); 203 return err; 204 } 205 206 static void tcf_skbmod_cleanup(struct tc_action *a) 207 { 208 struct tcf_skbmod *d = to_skbmod(a); 209 struct tcf_skbmod_params *p; 210 211 p = rcu_dereference_protected(d->skbmod_p, 1); 212 if (p) 213 kfree_rcu(p, rcu); 214 } 215 216 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, 217 int bind, int ref) 218 { 219 struct tcf_skbmod *d = to_skbmod(a); 220 unsigned char *b = skb_tail_pointer(skb); 221 struct tcf_skbmod_params *p; 222 struct tc_skbmod opt = { 223 .index = d->tcf_index, 224 .refcnt = refcount_read(&d->tcf_refcnt) - ref, 225 .bindcnt = atomic_read(&d->tcf_bindcnt) - bind, 226 }; 227 struct tcf_t t; 228 229 spin_lock_bh(&d->tcf_lock); 230 opt.action = d->tcf_action; 231 p = rcu_dereference_protected(d->skbmod_p, 232 lockdep_is_held(&d->tcf_lock)); 233 opt.flags = p->flags; 234 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt)) 235 goto nla_put_failure; 236 if ((p->flags & SKBMOD_F_DMAC) && 237 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst)) 238 goto nla_put_failure; 239 if ((p->flags & SKBMOD_F_SMAC) && 240 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src)) 241 goto nla_put_failure; 242 if ((p->flags & SKBMOD_F_ETYPE) && 243 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type))) 244 goto nla_put_failure; 245 246 tcf_tm_dump(&t, &d->tcf_tm); 247 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD)) 248 goto nla_put_failure; 249 250 spin_unlock_bh(&d->tcf_lock); 251 return skb->len; 252 nla_put_failure: 253 spin_unlock_bh(&d->tcf_lock); 254 nlmsg_trim(skb, b); 255 return -1; 256 } 257 258 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb, 259 struct netlink_callback *cb, int type, 260 const struct tc_action_ops *ops, 261 struct netlink_ext_ack *extack) 262 { 263 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 264 265 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 266 } 267 268 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index) 269 { 270 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 271 272 return tcf_idr_search(tn, a, index); 273 } 274 275 static struct tc_action_ops act_skbmod_ops = { 276 .kind = "skbmod", 277 .id = TCA_ACT_SKBMOD, 278 .owner = THIS_MODULE, 279 .act = tcf_skbmod_act, 280 .dump = tcf_skbmod_dump, 281 .init = tcf_skbmod_init, 282 .cleanup = tcf_skbmod_cleanup, 283 .walk = tcf_skbmod_walker, 284 .lookup = tcf_skbmod_search, 285 .size = sizeof(struct tcf_skbmod), 286 }; 287 288 static __net_init int skbmod_init_net(struct net *net) 289 { 290 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 291 292 return tc_action_net_init(tn, &act_skbmod_ops); 293 } 294 295 static void __net_exit skbmod_exit_net(struct list_head *net_list) 296 { 297 tc_action_net_exit(net_list, skbmod_net_id); 298 } 299 300 static struct pernet_operations skbmod_net_ops = { 301 .init = skbmod_init_net, 302 .exit_batch = skbmod_exit_net, 303 .id = &skbmod_net_id, 304 .size = sizeof(struct tc_action_net), 305 }; 306 307 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>"); 308 MODULE_DESCRIPTION("SKB data mod-ing"); 309 MODULE_LICENSE("GPL"); 310 311 static int __init skbmod_init_module(void) 312 { 313 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops); 314 } 315 316 static void __exit skbmod_cleanup_module(void) 317 { 318 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops); 319 } 320 321 module_init(skbmod_init_module); 322 module_exit(skbmod_cleanup_module); 323