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