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 .dumpit = psample_nl_cmd_get_group_dumpit, 104 /* can be retrieved by unprivileged users */ 105 } 106 }; 107 108 static struct genl_family psample_nl_family __ro_after_init = { 109 .name = PSAMPLE_GENL_NAME, 110 .version = PSAMPLE_GENL_VERSION, 111 .maxattr = PSAMPLE_ATTR_MAX, 112 .netnsok = true, 113 .module = THIS_MODULE, 114 .mcgrps = psample_nl_mcgrps, 115 .ops = psample_nl_ops, 116 .n_ops = ARRAY_SIZE(psample_nl_ops), 117 .n_mcgrps = ARRAY_SIZE(psample_nl_mcgrps), 118 }; 119 120 static void psample_group_notify(struct psample_group *group, 121 enum psample_command cmd) 122 { 123 struct sk_buff *msg; 124 int err; 125 126 msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); 127 if (!msg) 128 return; 129 130 err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI); 131 if (!err) 132 genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0, 133 PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC); 134 else 135 nlmsg_free(msg); 136 } 137 138 static struct psample_group *psample_group_create(struct net *net, 139 u32 group_num) 140 { 141 struct psample_group *group; 142 143 group = kzalloc(sizeof(*group), GFP_ATOMIC); 144 if (!group) 145 return NULL; 146 147 group->net = net; 148 group->group_num = group_num; 149 list_add_tail(&group->list, &psample_groups_list); 150 151 psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP); 152 return group; 153 } 154 155 static void psample_group_destroy(struct psample_group *group) 156 { 157 psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP); 158 list_del(&group->list); 159 kfree(group); 160 } 161 162 static struct psample_group * 163 psample_group_lookup(struct net *net, u32 group_num) 164 { 165 struct psample_group *group; 166 167 list_for_each_entry(group, &psample_groups_list, list) 168 if ((group->group_num == group_num) && (group->net == net)) 169 return group; 170 return NULL; 171 } 172 173 struct psample_group *psample_group_get(struct net *net, u32 group_num) 174 { 175 struct psample_group *group; 176 177 spin_lock(&psample_groups_lock); 178 179 group = psample_group_lookup(net, group_num); 180 if (!group) { 181 group = psample_group_create(net, group_num); 182 if (!group) 183 goto out; 184 } 185 group->refcount++; 186 187 out: 188 spin_unlock(&psample_groups_lock); 189 return group; 190 } 191 EXPORT_SYMBOL_GPL(psample_group_get); 192 193 void psample_group_put(struct psample_group *group) 194 { 195 spin_lock(&psample_groups_lock); 196 197 if (--group->refcount == 0) 198 psample_group_destroy(group); 199 200 spin_unlock(&psample_groups_lock); 201 } 202 EXPORT_SYMBOL_GPL(psample_group_put); 203 204 void psample_sample_packet(struct psample_group *group, struct sk_buff *skb, 205 u32 trunc_size, int in_ifindex, int out_ifindex, 206 u32 sample_rate) 207 { 208 struct sk_buff *nl_skb; 209 int data_len; 210 int meta_len; 211 void *data; 212 int ret; 213 214 meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) + 215 (out_ifindex ? nla_total_size(sizeof(u16)) : 0) + 216 nla_total_size(sizeof(u32)) + /* sample_rate */ 217 nla_total_size(sizeof(u32)) + /* orig_size */ 218 nla_total_size(sizeof(u32)) + /* group_num */ 219 nla_total_size(sizeof(u32)); /* seq */ 220 221 data_len = min(skb->len, trunc_size); 222 if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE) 223 data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN 224 - NLA_ALIGNTO; 225 226 nl_skb = genlmsg_new(meta_len + data_len, GFP_ATOMIC); 227 if (unlikely(!nl_skb)) 228 return; 229 230 data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0, 231 PSAMPLE_CMD_SAMPLE); 232 if (unlikely(!data)) 233 goto error; 234 235 if (in_ifindex) { 236 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex); 237 if (unlikely(ret < 0)) 238 goto error; 239 } 240 241 if (out_ifindex) { 242 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex); 243 if (unlikely(ret < 0)) 244 goto error; 245 } 246 247 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate); 248 if (unlikely(ret < 0)) 249 goto error; 250 251 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len); 252 if (unlikely(ret < 0)) 253 goto error; 254 255 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); 256 if (unlikely(ret < 0)) 257 goto error; 258 259 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++); 260 if (unlikely(ret < 0)) 261 goto error; 262 263 if (data_len) { 264 int nla_len = nla_total_size(data_len); 265 struct nlattr *nla; 266 267 nla = skb_put(nl_skb, nla_len); 268 nla->nla_type = PSAMPLE_ATTR_DATA; 269 nla->nla_len = nla_attr_size(data_len); 270 271 if (skb_copy_bits(skb, 0, nla_data(nla), data_len)) 272 goto error; 273 } 274 275 genlmsg_end(nl_skb, data); 276 genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0, 277 PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC); 278 279 return; 280 error: 281 pr_err_ratelimited("Could not create psample log message\n"); 282 nlmsg_free(nl_skb); 283 } 284 EXPORT_SYMBOL_GPL(psample_sample_packet); 285 286 static int __init psample_module_init(void) 287 { 288 return genl_register_family(&psample_nl_family); 289 } 290 291 static void __exit psample_module_exit(void) 292 { 293 genl_unregister_family(&psample_nl_family); 294 } 295 296 module_init(psample_module_init); 297 module_exit(psample_module_exit); 298 299 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>"); 300 MODULE_DESCRIPTION("netlink channel for packet sampling"); 301 MODULE_LICENSE("GPL v2"); 302