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_act(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 goto drop; 46 47 action = READ_ONCE(d->tcf_action); 48 if (unlikely(action == TC_ACT_SHOT)) 49 goto drop; 50 51 p = rcu_dereference_bh(d->skbmod_p); 52 flags = p->flags; 53 if (flags & SKBMOD_F_DMAC) 54 ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst); 55 if (flags & SKBMOD_F_SMAC) 56 ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src); 57 if (flags & SKBMOD_F_ETYPE) 58 eth_hdr(skb)->h_proto = p->eth_type; 59 60 if (flags & SKBMOD_F_SWAPMAC) { 61 u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */ 62 /*XXX: I am sure we can come up with more efficient swapping*/ 63 ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest); 64 ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source); 65 ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr); 66 } 67 68 return action; 69 70 drop: 71 qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats)); 72 return TC_ACT_SHOT; 73 } 74 75 static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = { 76 [TCA_SKBMOD_PARMS] = { .len = sizeof(struct tc_skbmod) }, 77 [TCA_SKBMOD_DMAC] = { .len = ETH_ALEN }, 78 [TCA_SKBMOD_SMAC] = { .len = ETH_ALEN }, 79 [TCA_SKBMOD_ETYPE] = { .type = NLA_U16 }, 80 }; 81 82 static int tcf_skbmod_init(struct net *net, struct nlattr *nla, 83 struct nlattr *est, struct tc_action **a, 84 int ovr, int bind, bool rtnl_held, 85 struct netlink_ext_ack *extack) 86 { 87 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 88 struct nlattr *tb[TCA_SKBMOD_MAX + 1]; 89 struct tcf_skbmod_params *p, *p_old; 90 struct tc_skbmod *parm; 91 struct tcf_skbmod *d; 92 bool exists = false; 93 u8 *daddr = NULL; 94 u8 *saddr = NULL; 95 u16 eth_type = 0; 96 u32 lflags = 0; 97 int ret = 0, err; 98 99 if (!nla) 100 return -EINVAL; 101 102 err = nla_parse_nested(tb, TCA_SKBMOD_MAX, nla, 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 if (parm->flags & SKBMOD_F_SWAPMAC) 126 lflags = SKBMOD_F_SWAPMAC; 127 128 err = tcf_idr_check_alloc(tn, &parm->index, a, bind); 129 if (err < 0) 130 return err; 131 exists = err; 132 if (exists && bind) 133 return 0; 134 135 if (!lflags) { 136 if (exists) 137 tcf_idr_release(*a, bind); 138 else 139 tcf_idr_cleanup(tn, parm->index); 140 return -EINVAL; 141 } 142 143 if (!exists) { 144 ret = tcf_idr_create(tn, parm->index, est, a, 145 &act_skbmod_ops, bind, true); 146 if (ret) { 147 tcf_idr_cleanup(tn, parm->index); 148 return ret; 149 } 150 151 ret = ACT_P_CREATED; 152 } else if (!ovr) { 153 tcf_idr_release(*a, bind); 154 return -EEXIST; 155 } 156 157 d = to_skbmod(*a); 158 159 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL); 160 if (unlikely(!p)) { 161 tcf_idr_release(*a, bind); 162 return -ENOMEM; 163 } 164 165 p->flags = lflags; 166 d->tcf_action = parm->action; 167 168 if (ovr) 169 spin_lock_bh(&d->tcf_lock); 170 /* Protected by tcf_lock if overwriting existing action. */ 171 p_old = rcu_dereference_protected(d->skbmod_p, 1); 172 173 if (lflags & SKBMOD_F_DMAC) 174 ether_addr_copy(p->eth_dst, daddr); 175 if (lflags & SKBMOD_F_SMAC) 176 ether_addr_copy(p->eth_src, saddr); 177 if (lflags & SKBMOD_F_ETYPE) 178 p->eth_type = htons(eth_type); 179 180 rcu_assign_pointer(d->skbmod_p, p); 181 if (ovr) 182 spin_unlock_bh(&d->tcf_lock); 183 184 if (p_old) 185 kfree_rcu(p_old, rcu); 186 187 if (ret == ACT_P_CREATED) 188 tcf_idr_insert(tn, *a); 189 return ret; 190 } 191 192 static void tcf_skbmod_cleanup(struct tc_action *a) 193 { 194 struct tcf_skbmod *d = to_skbmod(a); 195 struct tcf_skbmod_params *p; 196 197 p = rcu_dereference_protected(d->skbmod_p, 1); 198 if (p) 199 kfree_rcu(p, rcu); 200 } 201 202 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, 203 int bind, int ref) 204 { 205 struct tcf_skbmod *d = to_skbmod(a); 206 unsigned char *b = skb_tail_pointer(skb); 207 struct tcf_skbmod_params *p; 208 struct tc_skbmod opt = { 209 .index = d->tcf_index, 210 .refcnt = refcount_read(&d->tcf_refcnt) - ref, 211 .bindcnt = atomic_read(&d->tcf_bindcnt) - bind, 212 }; 213 struct tcf_t t; 214 215 spin_lock_bh(&d->tcf_lock); 216 opt.action = d->tcf_action; 217 p = rcu_dereference_protected(d->skbmod_p, 218 lockdep_is_held(&d->tcf_lock)); 219 opt.flags = p->flags; 220 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt)) 221 goto nla_put_failure; 222 if ((p->flags & SKBMOD_F_DMAC) && 223 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst)) 224 goto nla_put_failure; 225 if ((p->flags & SKBMOD_F_SMAC) && 226 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src)) 227 goto nla_put_failure; 228 if ((p->flags & SKBMOD_F_ETYPE) && 229 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type))) 230 goto nla_put_failure; 231 232 tcf_tm_dump(&t, &d->tcf_tm); 233 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD)) 234 goto nla_put_failure; 235 236 spin_unlock_bh(&d->tcf_lock); 237 return skb->len; 238 nla_put_failure: 239 spin_unlock_bh(&d->tcf_lock); 240 nlmsg_trim(skb, b); 241 return -1; 242 } 243 244 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb, 245 struct netlink_callback *cb, int type, 246 const struct tc_action_ops *ops, 247 struct netlink_ext_ack *extack) 248 { 249 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 250 251 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 252 } 253 254 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index) 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 struct tc_action_ops act_skbmod_ops = { 262 .kind = "skbmod", 263 .type = TCA_ACT_SKBMOD, 264 .owner = THIS_MODULE, 265 .act = tcf_skbmod_act, 266 .dump = tcf_skbmod_dump, 267 .init = tcf_skbmod_init, 268 .cleanup = tcf_skbmod_cleanup, 269 .walk = tcf_skbmod_walker, 270 .lookup = tcf_skbmod_search, 271 .size = sizeof(struct tcf_skbmod), 272 }; 273 274 static __net_init int skbmod_init_net(struct net *net) 275 { 276 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 277 278 return tc_action_net_init(tn, &act_skbmod_ops); 279 } 280 281 static void __net_exit skbmod_exit_net(struct list_head *net_list) 282 { 283 tc_action_net_exit(net_list, skbmod_net_id); 284 } 285 286 static struct pernet_operations skbmod_net_ops = { 287 .init = skbmod_init_net, 288 .exit_batch = skbmod_exit_net, 289 .id = &skbmod_net_id, 290 .size = sizeof(struct tc_action_net), 291 }; 292 293 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>"); 294 MODULE_DESCRIPTION("SKB data mod-ing"); 295 MODULE_LICENSE("GPL"); 296 297 static int __init skbmod_init_module(void) 298 { 299 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops); 300 } 301 302 static void __exit skbmod_cleanup_module(void) 303 { 304 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops); 305 } 306 307 module_init(skbmod_init_module); 308 module_exit(skbmod_cleanup_module); 309