1 /* 2 * net/psample/psample.c - Netlink channel for packet sampling 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/skbuff.h> 13 #include <linux/module.h> 14 #include <net/net_namespace.h> 15 #include <net/sock.h> 16 #include <net/netlink.h> 17 #include <net/genetlink.h> 18 #include <net/psample.h> 19 #include <linux/spinlock.h> 20 21 #define PSAMPLE_MAX_PACKET_SIZE 0xffff 22 23 static LIST_HEAD(psample_groups_list); 24 static DEFINE_SPINLOCK(psample_groups_lock); 25 26 /* multicast groups */ 27 enum psample_nl_multicast_groups { 28 PSAMPLE_NL_MCGRP_CONFIG, 29 PSAMPLE_NL_MCGRP_SAMPLE, 30 }; 31 32 static const struct genl_multicast_group psample_nl_mcgrps[] = { 33 [PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME }, 34 [PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME }, 35 }; 36 37 static struct genl_family psample_nl_family __ro_after_init; 38 39 static int psample_group_nl_fill(struct sk_buff *msg, 40 struct psample_group *group, 41 enum psample_command cmd, u32 portid, u32 seq, 42 int flags) 43 { 44 void *hdr; 45 int ret; 46 47 hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd); 48 if (!hdr) 49 return -EMSGSIZE; 50 51 ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); 52 if (ret < 0) 53 goto error; 54 55 ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount); 56 if (ret < 0) 57 goto error; 58 59 ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq); 60 if (ret < 0) 61 goto error; 62 63 genlmsg_end(msg, hdr); 64 return 0; 65 66 error: 67 genlmsg_cancel(msg, hdr); 68 return -EMSGSIZE; 69 } 70 71 static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg, 72 struct netlink_callback *cb) 73 { 74 struct psample_group *group; 75 int start = cb->args[0]; 76 int idx = 0; 77 int err; 78 79 spin_lock(&psample_groups_lock); 80 list_for_each_entry(group, &psample_groups_list, list) { 81 if (!net_eq(group->net, sock_net(msg->sk))) 82 continue; 83 if (idx < start) { 84 idx++; 85 continue; 86 } 87 err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP, 88 NETLINK_CB(cb->skb).portid, 89 cb->nlh->nlmsg_seq, NLM_F_MULTI); 90 if (err) 91 break; 92 idx++; 93 } 94 95 spin_unlock(&psample_groups_lock); 96 cb->args[0] = idx; 97 return msg->len; 98 } 99 100 static const struct genl_ops psample_nl_ops[] = { 101 { 102 .cmd = PSAMPLE_CMD_GET_GROUP, 103 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, 104 .dumpit = psample_nl_cmd_get_group_dumpit, 105 /* can be retrieved by unprivileged users */ 106 } 107 }; 108 109 static struct genl_family psample_nl_family __ro_after_init = { 110 .name = PSAMPLE_GENL_NAME, 111 .version = PSAMPLE_GENL_VERSION, 112 .maxattr = PSAMPLE_ATTR_MAX, 113 .netnsok = true, 114 .module = THIS_MODULE, 115 .mcgrps = psample_nl_mcgrps, 116 .ops = psample_nl_ops, 117 .n_ops = ARRAY_SIZE(psample_nl_ops), 118 .n_mcgrps = ARRAY_SIZE(psample_nl_mcgrps), 119 }; 120 121 static void psample_group_notify(struct psample_group *group, 122 enum psample_command cmd) 123 { 124 struct sk_buff *msg; 125 int err; 126 127 msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); 128 if (!msg) 129 return; 130 131 err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI); 132 if (!err) 133 genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0, 134 PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC); 135 else 136 nlmsg_free(msg); 137 } 138 139 static struct psample_group *psample_group_create(struct net *net, 140 u32 group_num) 141 { 142 struct psample_group *group; 143 144 group = kzalloc(sizeof(*group), GFP_ATOMIC); 145 if (!group) 146 return NULL; 147 148 group->net = net; 149 group->group_num = group_num; 150 list_add_tail(&group->list, &psample_groups_list); 151 152 psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP); 153 return group; 154 } 155 156 static void psample_group_destroy(struct psample_group *group) 157 { 158 psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP); 159 list_del(&group->list); 160 kfree(group); 161 } 162 163 static struct psample_group * 164 psample_group_lookup(struct net *net, u32 group_num) 165 { 166 struct psample_group *group; 167 168 list_for_each_entry(group, &psample_groups_list, list) 169 if ((group->group_num == group_num) && (group->net == net)) 170 return group; 171 return NULL; 172 } 173 174 struct psample_group *psample_group_get(struct net *net, u32 group_num) 175 { 176 struct psample_group *group; 177 178 spin_lock(&psample_groups_lock); 179 180 group = psample_group_lookup(net, group_num); 181 if (!group) { 182 group = psample_group_create(net, group_num); 183 if (!group) 184 goto out; 185 } 186 group->refcount++; 187 188 out: 189 spin_unlock(&psample_groups_lock); 190 return group; 191 } 192 EXPORT_SYMBOL_GPL(psample_group_get); 193 194 void psample_group_put(struct psample_group *group) 195 { 196 spin_lock(&psample_groups_lock); 197 198 if (--group->refcount == 0) 199 psample_group_destroy(group); 200 201 spin_unlock(&psample_groups_lock); 202 } 203 EXPORT_SYMBOL_GPL(psample_group_put); 204 205 void psample_sample_packet(struct psample_group *group, struct sk_buff *skb, 206 u32 trunc_size, int in_ifindex, int out_ifindex, 207 u32 sample_rate) 208 { 209 struct sk_buff *nl_skb; 210 int data_len; 211 int meta_len; 212 void *data; 213 int ret; 214 215 meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) + 216 (out_ifindex ? nla_total_size(sizeof(u16)) : 0) + 217 nla_total_size(sizeof(u32)) + /* sample_rate */ 218 nla_total_size(sizeof(u32)) + /* orig_size */ 219 nla_total_size(sizeof(u32)) + /* group_num */ 220 nla_total_size(sizeof(u32)); /* seq */ 221 222 data_len = min(skb->len, trunc_size); 223 if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE) 224 data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN 225 - NLA_ALIGNTO; 226 227 nl_skb = genlmsg_new(meta_len + data_len, GFP_ATOMIC); 228 if (unlikely(!nl_skb)) 229 return; 230 231 data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0, 232 PSAMPLE_CMD_SAMPLE); 233 if (unlikely(!data)) 234 goto error; 235 236 if (in_ifindex) { 237 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex); 238 if (unlikely(ret < 0)) 239 goto error; 240 } 241 242 if (out_ifindex) { 243 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex); 244 if (unlikely(ret < 0)) 245 goto error; 246 } 247 248 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate); 249 if (unlikely(ret < 0)) 250 goto error; 251 252 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len); 253 if (unlikely(ret < 0)) 254 goto error; 255 256 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); 257 if (unlikely(ret < 0)) 258 goto error; 259 260 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++); 261 if (unlikely(ret < 0)) 262 goto error; 263 264 if (data_len) { 265 int nla_len = nla_total_size(data_len); 266 struct nlattr *nla; 267 268 nla = skb_put(nl_skb, nla_len); 269 nla->nla_type = PSAMPLE_ATTR_DATA; 270 nla->nla_len = nla_attr_size(data_len); 271 272 if (skb_copy_bits(skb, 0, nla_data(nla), data_len)) 273 goto error; 274 } 275 276 genlmsg_end(nl_skb, data); 277 genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0, 278 PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC); 279 280 return; 281 error: 282 pr_err_ratelimited("Could not create psample log message\n"); 283 nlmsg_free(nl_skb); 284 } 285 EXPORT_SYMBOL_GPL(psample_sample_packet); 286 287 static int __init psample_module_init(void) 288 { 289 return genl_register_family(&psample_nl_family); 290 } 291 292 static void __exit psample_module_exit(void) 293 { 294 genl_unregister_family(&psample_nl_family); 295 } 296 297 module_init(psample_module_init); 298 module_exit(psample_module_exit); 299 300 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>"); 301 MODULE_DESCRIPTION("netlink channel for packet sampling"); 302 MODULE_LICENSE("GPL v2"); 303