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 26 #include <linux/if_arp.h> 27 28 static unsigned int sample_net_id; 29 static struct tc_action_ops act_sample_ops; 30 31 static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = { 32 [TCA_SAMPLE_PARMS] = { .len = sizeof(struct tc_sample) }, 33 [TCA_SAMPLE_RATE] = { .type = NLA_U32 }, 34 [TCA_SAMPLE_TRUNC_SIZE] = { .type = NLA_U32 }, 35 [TCA_SAMPLE_PSAMPLE_GROUP] = { .type = NLA_U32 }, 36 }; 37 38 static int tcf_sample_init(struct net *net, struct nlattr *nla, 39 struct nlattr *est, struct tc_action **a, int ovr, 40 int bind) 41 { 42 struct tc_action_net *tn = net_generic(net, sample_net_id); 43 struct nlattr *tb[TCA_SAMPLE_MAX + 1]; 44 struct psample_group *psample_group; 45 struct tc_sample *parm; 46 struct tcf_sample *s; 47 bool exists = false; 48 int ret; 49 50 if (!nla) 51 return -EINVAL; 52 ret = nla_parse_nested(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL); 53 if (ret < 0) 54 return ret; 55 if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] || 56 !tb[TCA_SAMPLE_PSAMPLE_GROUP]) 57 return -EINVAL; 58 59 parm = nla_data(tb[TCA_SAMPLE_PARMS]); 60 61 exists = tcf_idr_check(tn, parm->index, a, bind); 62 if (exists && bind) 63 return 0; 64 65 if (!exists) { 66 ret = tcf_idr_create(tn, parm->index, est, a, 67 &act_sample_ops, bind, false); 68 if (ret) 69 return ret; 70 ret = ACT_P_CREATED; 71 } else { 72 tcf_idr_release(*a, bind); 73 if (!ovr) 74 return -EEXIST; 75 } 76 s = to_sample(*a); 77 78 s->tcf_action = parm->action; 79 s->rate = nla_get_u32(tb[TCA_SAMPLE_RATE]); 80 s->psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]); 81 psample_group = psample_group_get(net, s->psample_group_num); 82 if (!psample_group) { 83 if (ret == ACT_P_CREATED) 84 tcf_idr_release(*a, bind); 85 return -ENOMEM; 86 } 87 RCU_INIT_POINTER(s->psample_group, psample_group); 88 89 if (tb[TCA_SAMPLE_TRUNC_SIZE]) { 90 s->truncate = true; 91 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]); 92 } 93 94 if (ret == ACT_P_CREATED) 95 tcf_idr_insert(tn, *a); 96 return ret; 97 } 98 99 static void tcf_sample_cleanup_rcu(struct rcu_head *rcu) 100 { 101 struct tcf_sample *s = container_of(rcu, struct tcf_sample, rcu); 102 struct psample_group *psample_group; 103 104 psample_group = rcu_dereference_protected(s->psample_group, 1); 105 RCU_INIT_POINTER(s->psample_group, NULL); 106 psample_group_put(psample_group); 107 } 108 109 static void tcf_sample_cleanup(struct tc_action *a, int bind) 110 { 111 struct tcf_sample *s = to_sample(a); 112 113 call_rcu(&s->rcu, tcf_sample_cleanup_rcu); 114 } 115 116 static bool tcf_sample_dev_ok_push(struct net_device *dev) 117 { 118 switch (dev->type) { 119 case ARPHRD_TUNNEL: 120 case ARPHRD_TUNNEL6: 121 case ARPHRD_SIT: 122 case ARPHRD_IPGRE: 123 case ARPHRD_VOID: 124 case ARPHRD_NONE: 125 return false; 126 default: 127 return true; 128 } 129 } 130 131 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a, 132 struct tcf_result *res) 133 { 134 struct tcf_sample *s = to_sample(a); 135 struct psample_group *psample_group; 136 int retval; 137 int size; 138 int iif; 139 int oif; 140 141 tcf_lastuse_update(&s->tcf_tm); 142 bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb); 143 retval = READ_ONCE(s->tcf_action); 144 145 rcu_read_lock(); 146 psample_group = rcu_dereference(s->psample_group); 147 148 /* randomly sample packets according to rate */ 149 if (psample_group && (prandom_u32() % s->rate == 0)) { 150 if (!skb_at_tc_ingress(skb)) { 151 iif = skb->skb_iif; 152 oif = skb->dev->ifindex; 153 } else { 154 iif = skb->dev->ifindex; 155 oif = 0; 156 } 157 158 /* on ingress, the mac header gets popped, so push it back */ 159 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev)) 160 skb_push(skb, skb->mac_len); 161 162 size = s->truncate ? s->trunc_size : skb->len; 163 psample_sample_packet(psample_group, skb, size, iif, oif, 164 s->rate); 165 166 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev)) 167 skb_pull(skb, skb->mac_len); 168 } 169 170 rcu_read_unlock(); 171 return retval; 172 } 173 174 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a, 175 int bind, int ref) 176 { 177 unsigned char *b = skb_tail_pointer(skb); 178 struct tcf_sample *s = to_sample(a); 179 struct tc_sample opt = { 180 .index = s->tcf_index, 181 .action = s->tcf_action, 182 .refcnt = s->tcf_refcnt - ref, 183 .bindcnt = s->tcf_bindcnt - bind, 184 }; 185 struct tcf_t t; 186 187 if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt)) 188 goto nla_put_failure; 189 190 tcf_tm_dump(&t, &s->tcf_tm); 191 if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD)) 192 goto nla_put_failure; 193 194 if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate)) 195 goto nla_put_failure; 196 197 if (s->truncate) 198 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size)) 199 goto nla_put_failure; 200 201 if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num)) 202 goto nla_put_failure; 203 return skb->len; 204 205 nla_put_failure: 206 nlmsg_trim(skb, b); 207 return -1; 208 } 209 210 static int tcf_sample_walker(struct net *net, struct sk_buff *skb, 211 struct netlink_callback *cb, int type, 212 const struct tc_action_ops *ops) 213 { 214 struct tc_action_net *tn = net_generic(net, sample_net_id); 215 216 return tcf_generic_walker(tn, skb, cb, type, ops); 217 } 218 219 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index) 220 { 221 struct tc_action_net *tn = net_generic(net, sample_net_id); 222 223 return tcf_idr_search(tn, a, index); 224 } 225 226 static struct tc_action_ops act_sample_ops = { 227 .kind = "sample", 228 .type = TCA_ACT_SAMPLE, 229 .owner = THIS_MODULE, 230 .act = tcf_sample_act, 231 .dump = tcf_sample_dump, 232 .init = tcf_sample_init, 233 .cleanup = tcf_sample_cleanup, 234 .walk = tcf_sample_walker, 235 .lookup = tcf_sample_search, 236 .size = sizeof(struct tcf_sample), 237 }; 238 239 static __net_init int sample_init_net(struct net *net) 240 { 241 struct tc_action_net *tn = net_generic(net, sample_net_id); 242 243 return tc_action_net_init(tn, &act_sample_ops); 244 } 245 246 static void __net_exit sample_exit_net(struct net *net) 247 { 248 struct tc_action_net *tn = net_generic(net, sample_net_id); 249 250 tc_action_net_exit(tn); 251 } 252 253 static struct pernet_operations sample_net_ops = { 254 .init = sample_init_net, 255 .exit = sample_exit_net, 256 .id = &sample_net_id, 257 .size = sizeof(struct tc_action_net), 258 }; 259 260 static int __init sample_init_module(void) 261 { 262 return tcf_register_action(&act_sample_ops, &sample_net_ops); 263 } 264 265 static void __exit sample_cleanup_module(void) 266 { 267 rcu_barrier(); 268 tcf_unregister_action(&act_sample_ops, &sample_net_ops); 269 } 270 271 module_init(sample_init_module); 272 module_exit(sample_cleanup_module); 273 274 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>"); 275 MODULE_DESCRIPTION("Packet sampling action"); 276 MODULE_LICENSE("GPL v2"); 277