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) 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 tc_skbmod *parm; 93 struct tcf_skbmod *d; 94 bool exists = false; 95 u8 *daddr = NULL; 96 u8 *saddr = NULL; 97 u16 eth_type = 0; 98 u32 lflags = 0; 99 int ret = 0, err; 100 101 if (!nla) 102 return -EINVAL; 103 104 err = nla_parse_nested(tb, TCA_SKBMOD_MAX, nla, skbmod_policy, NULL); 105 if (err < 0) 106 return err; 107 108 if (!tb[TCA_SKBMOD_PARMS]) 109 return -EINVAL; 110 111 if (tb[TCA_SKBMOD_DMAC]) { 112 daddr = nla_data(tb[TCA_SKBMOD_DMAC]); 113 lflags |= SKBMOD_F_DMAC; 114 } 115 116 if (tb[TCA_SKBMOD_SMAC]) { 117 saddr = nla_data(tb[TCA_SKBMOD_SMAC]); 118 lflags |= SKBMOD_F_SMAC; 119 } 120 121 if (tb[TCA_SKBMOD_ETYPE]) { 122 eth_type = nla_get_u16(tb[TCA_SKBMOD_ETYPE]); 123 lflags |= SKBMOD_F_ETYPE; 124 } 125 126 parm = nla_data(tb[TCA_SKBMOD_PARMS]); 127 if (parm->flags & SKBMOD_F_SWAPMAC) 128 lflags = SKBMOD_F_SWAPMAC; 129 130 exists = tcf_idr_check(tn, parm->index, a, bind); 131 if (exists && bind) 132 return 0; 133 134 if (!lflags) 135 return -EINVAL; 136 137 if (!exists) { 138 ret = tcf_idr_create(tn, parm->index, est, a, 139 &act_skbmod_ops, bind, true); 140 if (ret) 141 return ret; 142 143 ret = ACT_P_CREATED; 144 } else { 145 tcf_idr_release(*a, bind); 146 if (!ovr) 147 return -EEXIST; 148 } 149 150 d = to_skbmod(*a); 151 152 ASSERT_RTNL(); 153 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL); 154 if (unlikely(!p)) { 155 if (ovr) 156 tcf_idr_release(*a, bind); 157 return -ENOMEM; 158 } 159 160 p->flags = lflags; 161 d->tcf_action = parm->action; 162 163 p_old = rtnl_dereference(d->skbmod_p); 164 165 if (ovr) 166 spin_lock_bh(&d->tcf_lock); 167 168 if (lflags & SKBMOD_F_DMAC) 169 ether_addr_copy(p->eth_dst, daddr); 170 if (lflags & SKBMOD_F_SMAC) 171 ether_addr_copy(p->eth_src, saddr); 172 if (lflags & SKBMOD_F_ETYPE) 173 p->eth_type = htons(eth_type); 174 175 rcu_assign_pointer(d->skbmod_p, p); 176 if (ovr) 177 spin_unlock_bh(&d->tcf_lock); 178 179 if (p_old) 180 kfree_rcu(p_old, rcu); 181 182 if (ret == ACT_P_CREATED) 183 tcf_idr_insert(tn, *a); 184 return ret; 185 } 186 187 static void tcf_skbmod_cleanup(struct tc_action *a) 188 { 189 struct tcf_skbmod *d = to_skbmod(a); 190 struct tcf_skbmod_params *p; 191 192 p = rcu_dereference_protected(d->skbmod_p, 1); 193 kfree_rcu(p, rcu); 194 } 195 196 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, 197 int bind, int ref) 198 { 199 struct tcf_skbmod *d = to_skbmod(a); 200 unsigned char *b = skb_tail_pointer(skb); 201 struct tcf_skbmod_params *p = rtnl_dereference(d->skbmod_p); 202 struct tc_skbmod opt = { 203 .index = d->tcf_index, 204 .refcnt = d->tcf_refcnt - ref, 205 .bindcnt = d->tcf_bindcnt - bind, 206 .action = d->tcf_action, 207 }; 208 struct tcf_t t; 209 210 opt.flags = p->flags; 211 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt)) 212 goto nla_put_failure; 213 if ((p->flags & SKBMOD_F_DMAC) && 214 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst)) 215 goto nla_put_failure; 216 if ((p->flags & SKBMOD_F_SMAC) && 217 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src)) 218 goto nla_put_failure; 219 if ((p->flags & SKBMOD_F_ETYPE) && 220 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type))) 221 goto nla_put_failure; 222 223 tcf_tm_dump(&t, &d->tcf_tm); 224 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD)) 225 goto nla_put_failure; 226 227 return skb->len; 228 nla_put_failure: 229 nlmsg_trim(skb, b); 230 return -1; 231 } 232 233 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb, 234 struct netlink_callback *cb, int type, 235 const struct tc_action_ops *ops) 236 { 237 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 238 239 return tcf_generic_walker(tn, skb, cb, type, ops); 240 } 241 242 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index) 243 { 244 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 245 246 return tcf_idr_search(tn, a, index); 247 } 248 249 static struct tc_action_ops act_skbmod_ops = { 250 .kind = "skbmod", 251 .type = TCA_ACT_SKBMOD, 252 .owner = THIS_MODULE, 253 .act = tcf_skbmod_run, 254 .dump = tcf_skbmod_dump, 255 .init = tcf_skbmod_init, 256 .cleanup = tcf_skbmod_cleanup, 257 .walk = tcf_skbmod_walker, 258 .lookup = tcf_skbmod_search, 259 .size = sizeof(struct tcf_skbmod), 260 }; 261 262 static __net_init int skbmod_init_net(struct net *net) 263 { 264 struct tc_action_net *tn = net_generic(net, skbmod_net_id); 265 266 return tc_action_net_init(tn, &act_skbmod_ops); 267 } 268 269 static void __net_exit skbmod_exit_net(struct list_head *net_list) 270 { 271 tc_action_net_exit(net_list, skbmod_net_id); 272 } 273 274 static struct pernet_operations skbmod_net_ops = { 275 .init = skbmod_init_net, 276 .exit_batch = skbmod_exit_net, 277 .id = &skbmod_net_id, 278 .size = sizeof(struct tc_action_net), 279 }; 280 281 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>"); 282 MODULE_DESCRIPTION("SKB data mod-ing"); 283 MODULE_LICENSE("GPL"); 284 285 static int __init skbmod_init_module(void) 286 { 287 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops); 288 } 289 290 static void __exit skbmod_cleanup_module(void) 291 { 292 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops); 293 } 294 295 module_init(skbmod_init_module); 296 module_exit(skbmod_cleanup_module); 297