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