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 exists = tcf_idr_check(tn, parm->index, a, bind); 132 if (exists && bind) 133 return 0; 134 135 if (!lflags) { 136 if (exists) 137 tcf_idr_release(*a, bind); 138 return -EINVAL; 139 } 140 141 if (!exists) { 142 ret = tcf_idr_create(tn, parm->index, est, a, 143 &act_skbmod_ops, bind, true); 144 if (ret) 145 return ret; 146 147 ret = ACT_P_CREATED; 148 } else if (!ovr) { 149 tcf_idr_release(*a, bind); 150 return -EEXIST; 151 } 152 153 d = to_skbmod(*a); 154 155 ASSERT_RTNL(); 156 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL); 157 if (unlikely(!p)) { 158 tcf_idr_release(*a, bind); 159 return -ENOMEM; 160 } 161 162 p->flags = lflags; 163 d->tcf_action = parm->action; 164 165 p_old = rtnl_dereference(d->skbmod_p); 166 167 if (ovr) 168 spin_lock_bh(&d->tcf_lock); 169 170 if (lflags & SKBMOD_F_DMAC) 171 ether_addr_copy(p->eth_dst, daddr); 172 if (lflags & SKBMOD_F_SMAC) 173 ether_addr_copy(p->eth_src, saddr); 174 if (lflags & SKBMOD_F_ETYPE) 175 p->eth_type = htons(eth_type); 176 177 rcu_assign_pointer(d->skbmod_p, p); 178 if (ovr) 179 spin_unlock_bh(&d->tcf_lock); 180 181 if (p_old) 182 kfree_rcu(p_old, rcu); 183 184 if (ret == ACT_P_CREATED) 185 tcf_idr_insert(tn, *a); 186 return ret; 187 } 188 189 static void tcf_skbmod_cleanup(struct tc_action *a) 190 { 191 struct tcf_skbmod *d = to_skbmod(a); 192 struct tcf_skbmod_params *p; 193 194 p = rcu_dereference_protected(d->skbmod_p, 1); 195 if (p) 196 kfree_rcu(p, rcu); 197 } 198 199 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, 200 int bind, int ref) 201 { 202 struct tcf_skbmod *d = to_skbmod(a); 203 unsigned char *b = skb_tail_pointer(skb); 204 struct tcf_skbmod_params *p = rtnl_dereference(d->skbmod_p); 205 struct tc_skbmod opt = { 206 .index = d->tcf_index, 207 .refcnt = refcount_read(&d->tcf_refcnt) - ref, 208 .bindcnt = atomic_read(&d->tcf_bindcnt) - bind, 209 .action = d->tcf_action, 210 }; 211 struct tcf_t t; 212 213 opt.flags = p->flags; 214 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt)) 215 goto nla_put_failure; 216 if ((p->flags & SKBMOD_F_DMAC) && 217 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst)) 218 goto nla_put_failure; 219 if ((p->flags & SKBMOD_F_SMAC) && 220 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src)) 221 goto nla_put_failure; 222 if ((p->flags & SKBMOD_F_ETYPE) && 223 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type))) 224 goto nla_put_failure; 225 226 tcf_tm_dump(&t, &d->tcf_tm); 227 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD)) 228 goto nla_put_failure; 229 230 return skb->len; 231 nla_put_failure: 232 nlmsg_trim(skb, b); 233 return -1; 234 } 235 236 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb, 237 struct netlink_callback *cb, int type, 238 const struct tc_action_ops *ops, 239 struct netlink_ext_ack *extack) 240 { 241 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 242 243 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 244 } 245 246 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index, 247 struct netlink_ext_ack *extack) 248 { 249 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 250 251 return tcf_idr_search(tn, a, index); 252 } 253 254 static int tcf_skbmod_delete(struct net *net, u32 index) 255 { 256 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 257 258 return tcf_idr_delete_index(tn, 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_run, 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 .delete = tcf_skbmod_delete, 272 .size = sizeof(struct tcf_skbmod), 273 }; 274 275 static __net_init int skbmod_init_net(struct net *net) 276 { 277 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 278 279 return tc_action_net_init(tn, &act_skbmod_ops); 280 } 281 282 static void __net_exit skbmod_exit_net(struct list_head *net_list) 283 { 284 tc_action_net_exit(net_list, skbmod_net_id); 285 } 286 287 static struct pernet_operations skbmod_net_ops = { 288 .init = skbmod_init_net, 289 .exit_batch = skbmod_exit_net, 290 .id = &skbmod_net_id, 291 .size = sizeof(struct tc_action_net), 292 }; 293 294 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>"); 295 MODULE_DESCRIPTION("SKB data mod-ing"); 296 MODULE_LICENSE("GPL"); 297 298 static int __init skbmod_init_module(void) 299 { 300 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops); 301 } 302 303 static void __exit skbmod_cleanup_module(void) 304 { 305 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops); 306 } 307 308 module_init(skbmod_init_module); 309 module_exit(skbmod_cleanup_module); 310