1 /* 2 * net/sched/act_sample.c - Packet sampling tc action 3 * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 */ 9 10 #include <linux/types.h> 11 #include <linux/kernel.h> 12 #include <linux/string.h> 13 #include <linux/errno.h> 14 #include <linux/skbuff.h> 15 #include <linux/rtnetlink.h> 16 #include <linux/module.h> 17 #include <linux/init.h> 18 #include <linux/gfp.h> 19 #include <net/net_namespace.h> 20 #include <net/netlink.h> 21 #include <net/pkt_sched.h> 22 #include <linux/tc_act/tc_sample.h> 23 #include <net/tc_act/tc_sample.h> 24 #include <net/psample.h> 25 #include <net/pkt_cls.h> 26 27 #include <linux/if_arp.h> 28 29 static unsigned int sample_net_id; 30 static struct tc_action_ops act_sample_ops; 31 32 static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = { 33 [TCA_SAMPLE_PARMS] = { .len = sizeof(struct tc_sample) }, 34 [TCA_SAMPLE_RATE] = { .type = NLA_U32 }, 35 [TCA_SAMPLE_TRUNC_SIZE] = { .type = NLA_U32 }, 36 [TCA_SAMPLE_PSAMPLE_GROUP] = { .type = NLA_U32 }, 37 }; 38 39 static int tcf_sample_init(struct net *net, struct nlattr *nla, 40 struct nlattr *est, struct tc_action **a, int ovr, 41 int bind, bool rtnl_held, struct tcf_proto *tp, 42 struct netlink_ext_ack *extack) 43 { 44 struct tc_action_net *tn = net_generic(net, sample_net_id); 45 struct nlattr *tb[TCA_SAMPLE_MAX + 1]; 46 struct psample_group *psample_group; 47 struct tcf_chain *goto_ch = NULL; 48 u32 psample_group_num, rate; 49 struct tc_sample *parm; 50 struct tcf_sample *s; 51 bool exists = false; 52 int ret, err; 53 54 if (!nla) 55 return -EINVAL; 56 ret = nla_parse_nested(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL); 57 if (ret < 0) 58 return ret; 59 if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] || 60 !tb[TCA_SAMPLE_PSAMPLE_GROUP]) 61 return -EINVAL; 62 63 parm = nla_data(tb[TCA_SAMPLE_PARMS]); 64 65 err = tcf_idr_check_alloc(tn, &parm->index, a, bind); 66 if (err < 0) 67 return err; 68 exists = err; 69 if (exists && bind) 70 return 0; 71 72 if (!exists) { 73 ret = tcf_idr_create(tn, parm->index, est, a, 74 &act_sample_ops, bind, true); 75 if (ret) { 76 tcf_idr_cleanup(tn, parm->index); 77 return ret; 78 } 79 ret = ACT_P_CREATED; 80 } else if (!ovr) { 81 tcf_idr_release(*a, bind); 82 return -EEXIST; 83 } 84 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); 85 if (err < 0) 86 goto release_idr; 87 88 rate = nla_get_u32(tb[TCA_SAMPLE_RATE]); 89 if (!rate) { 90 NL_SET_ERR_MSG(extack, "invalid sample rate"); 91 err = -EINVAL; 92 goto put_chain; 93 } 94 psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]); 95 psample_group = psample_group_get(net, psample_group_num); 96 if (!psample_group) { 97 err = -ENOMEM; 98 goto put_chain; 99 } 100 101 s = to_sample(*a); 102 103 spin_lock_bh(&s->tcf_lock); 104 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); 105 s->rate = rate; 106 s->psample_group_num = psample_group_num; 107 RCU_INIT_POINTER(s->psample_group, psample_group); 108 109 if (tb[TCA_SAMPLE_TRUNC_SIZE]) { 110 s->truncate = true; 111 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]); 112 } 113 spin_unlock_bh(&s->tcf_lock); 114 if (goto_ch) 115 tcf_chain_put_by_act(goto_ch); 116 117 if (ret == ACT_P_CREATED) 118 tcf_idr_insert(tn, *a); 119 return ret; 120 put_chain: 121 if (goto_ch) 122 tcf_chain_put_by_act(goto_ch); 123 release_idr: 124 tcf_idr_release(*a, bind); 125 return err; 126 } 127 128 static void tcf_sample_cleanup(struct tc_action *a) 129 { 130 struct tcf_sample *s = to_sample(a); 131 struct psample_group *psample_group; 132 133 /* last reference to action, no need to lock */ 134 psample_group = rcu_dereference_protected(s->psample_group, 1); 135 RCU_INIT_POINTER(s->psample_group, NULL); 136 if (psample_group) 137 psample_group_put(psample_group); 138 } 139 140 static bool tcf_sample_dev_ok_push(struct net_device *dev) 141 { 142 switch (dev->type) { 143 case ARPHRD_TUNNEL: 144 case ARPHRD_TUNNEL6: 145 case ARPHRD_SIT: 146 case ARPHRD_IPGRE: 147 case ARPHRD_VOID: 148 case ARPHRD_NONE: 149 return false; 150 default: 151 return true; 152 } 153 } 154 155 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a, 156 struct tcf_result *res) 157 { 158 struct tcf_sample *s = to_sample(a); 159 struct psample_group *psample_group; 160 int retval; 161 int size; 162 int iif; 163 int oif; 164 165 tcf_lastuse_update(&s->tcf_tm); 166 bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb); 167 retval = READ_ONCE(s->tcf_action); 168 169 psample_group = rcu_dereference_bh(s->psample_group); 170 171 /* randomly sample packets according to rate */ 172 if (psample_group && (prandom_u32() % s->rate == 0)) { 173 if (!skb_at_tc_ingress(skb)) { 174 iif = skb->skb_iif; 175 oif = skb->dev->ifindex; 176 } else { 177 iif = skb->dev->ifindex; 178 oif = 0; 179 } 180 181 /* on ingress, the mac header gets popped, so push it back */ 182 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev)) 183 skb_push(skb, skb->mac_len); 184 185 size = s->truncate ? s->trunc_size : skb->len; 186 psample_sample_packet(psample_group, skb, size, iif, oif, 187 s->rate); 188 189 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev)) 190 skb_pull(skb, skb->mac_len); 191 } 192 193 return retval; 194 } 195 196 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a, 197 int bind, int ref) 198 { 199 unsigned char *b = skb_tail_pointer(skb); 200 struct tcf_sample *s = to_sample(a); 201 struct tc_sample opt = { 202 .index = s->tcf_index, 203 .refcnt = refcount_read(&s->tcf_refcnt) - ref, 204 .bindcnt = atomic_read(&s->tcf_bindcnt) - bind, 205 }; 206 struct tcf_t t; 207 208 spin_lock_bh(&s->tcf_lock); 209 opt.action = s->tcf_action; 210 if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt)) 211 goto nla_put_failure; 212 213 tcf_tm_dump(&t, &s->tcf_tm); 214 if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD)) 215 goto nla_put_failure; 216 217 if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate)) 218 goto nla_put_failure; 219 220 if (s->truncate) 221 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size)) 222 goto nla_put_failure; 223 224 if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num)) 225 goto nla_put_failure; 226 spin_unlock_bh(&s->tcf_lock); 227 228 return skb->len; 229 230 nla_put_failure: 231 spin_unlock_bh(&s->tcf_lock); 232 nlmsg_trim(skb, b); 233 return -1; 234 } 235 236 static int tcf_sample_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, sample_net_id); 242 243 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 244 } 245 246 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index) 247 { 248 struct tc_action_net *tn = net_generic(net, sample_net_id); 249 250 return tcf_idr_search(tn, a, index); 251 } 252 253 static struct tc_action_ops act_sample_ops = { 254 .kind = "sample", 255 .id = TCA_ID_SAMPLE, 256 .owner = THIS_MODULE, 257 .act = tcf_sample_act, 258 .dump = tcf_sample_dump, 259 .init = tcf_sample_init, 260 .cleanup = tcf_sample_cleanup, 261 .walk = tcf_sample_walker, 262 .lookup = tcf_sample_search, 263 .size = sizeof(struct tcf_sample), 264 }; 265 266 static __net_init int sample_init_net(struct net *net) 267 { 268 struct tc_action_net *tn = net_generic(net, sample_net_id); 269 270 return tc_action_net_init(tn, &act_sample_ops); 271 } 272 273 static void __net_exit sample_exit_net(struct list_head *net_list) 274 { 275 tc_action_net_exit(net_list, sample_net_id); 276 } 277 278 static struct pernet_operations sample_net_ops = { 279 .init = sample_init_net, 280 .exit_batch = sample_exit_net, 281 .id = &sample_net_id, 282 .size = sizeof(struct tc_action_net), 283 }; 284 285 static int __init sample_init_module(void) 286 { 287 return tcf_register_action(&act_sample_ops, &sample_net_ops); 288 } 289 290 static void __exit sample_cleanup_module(void) 291 { 292 tcf_unregister_action(&act_sample_ops, &sample_net_ops); 293 } 294 295 module_init(sample_init_module); 296 module_exit(sample_cleanup_module); 297 298 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>"); 299 MODULE_DESCRIPTION("Packet sampling action"); 300 MODULE_LICENSE("GPL v2"); 301