1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * net/psample/psample.c - Netlink channel for packet sampling 4 * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com> 5 */ 6 7 #include <linux/types.h> 8 #include <linux/kernel.h> 9 #include <linux/skbuff.h> 10 #include <linux/module.h> 11 #include <net/net_namespace.h> 12 #include <net/sock.h> 13 #include <net/netlink.h> 14 #include <net/genetlink.h> 15 #include <net/psample.h> 16 #include <linux/spinlock.h> 17 18 #define PSAMPLE_MAX_PACKET_SIZE 0xffff 19 20 static LIST_HEAD(psample_groups_list); 21 static DEFINE_SPINLOCK(psample_groups_lock); 22 23 /* multicast groups */ 24 enum psample_nl_multicast_groups { 25 PSAMPLE_NL_MCGRP_CONFIG, 26 PSAMPLE_NL_MCGRP_SAMPLE, 27 }; 28 29 static const struct genl_multicast_group psample_nl_mcgrps[] = { 30 [PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME }, 31 [PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME }, 32 }; 33 34 static struct genl_family psample_nl_family __ro_after_init; 35 36 static int psample_group_nl_fill(struct sk_buff *msg, 37 struct psample_group *group, 38 enum psample_command cmd, u32 portid, u32 seq, 39 int flags) 40 { 41 void *hdr; 42 int ret; 43 44 hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd); 45 if (!hdr) 46 return -EMSGSIZE; 47 48 ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); 49 if (ret < 0) 50 goto error; 51 52 ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount); 53 if (ret < 0) 54 goto error; 55 56 ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq); 57 if (ret < 0) 58 goto error; 59 60 genlmsg_end(msg, hdr); 61 return 0; 62 63 error: 64 genlmsg_cancel(msg, hdr); 65 return -EMSGSIZE; 66 } 67 68 static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg, 69 struct netlink_callback *cb) 70 { 71 struct psample_group *group; 72 int start = cb->args[0]; 73 int idx = 0; 74 int err; 75 76 spin_lock_bh(&psample_groups_lock); 77 list_for_each_entry(group, &psample_groups_list, list) { 78 if (!net_eq(group->net, sock_net(msg->sk))) 79 continue; 80 if (idx < start) { 81 idx++; 82 continue; 83 } 84 err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP, 85 NETLINK_CB(cb->skb).portid, 86 cb->nlh->nlmsg_seq, NLM_F_MULTI); 87 if (err) 88 break; 89 idx++; 90 } 91 92 spin_unlock_bh(&psample_groups_lock); 93 cb->args[0] = idx; 94 return msg->len; 95 } 96 97 static const struct genl_ops psample_nl_ops[] = { 98 { 99 .cmd = PSAMPLE_CMD_GET_GROUP, 100 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, 101 .dumpit = psample_nl_cmd_get_group_dumpit, 102 /* can be retrieved by unprivileged users */ 103 } 104 }; 105 106 static struct genl_family psample_nl_family __ro_after_init = { 107 .name = PSAMPLE_GENL_NAME, 108 .version = PSAMPLE_GENL_VERSION, 109 .maxattr = PSAMPLE_ATTR_MAX, 110 .netnsok = true, 111 .module = THIS_MODULE, 112 .mcgrps = psample_nl_mcgrps, 113 .ops = psample_nl_ops, 114 .n_ops = ARRAY_SIZE(psample_nl_ops), 115 .n_mcgrps = ARRAY_SIZE(psample_nl_mcgrps), 116 }; 117 118 static void psample_group_notify(struct psample_group *group, 119 enum psample_command cmd) 120 { 121 struct sk_buff *msg; 122 int err; 123 124 msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); 125 if (!msg) 126 return; 127 128 err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI); 129 if (!err) 130 genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0, 131 PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC); 132 else 133 nlmsg_free(msg); 134 } 135 136 static struct psample_group *psample_group_create(struct net *net, 137 u32 group_num) 138 { 139 struct psample_group *group; 140 141 group = kzalloc(sizeof(*group), GFP_ATOMIC); 142 if (!group) 143 return NULL; 144 145 group->net = net; 146 group->group_num = group_num; 147 list_add_tail(&group->list, &psample_groups_list); 148 149 psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP); 150 return group; 151 } 152 153 static void psample_group_destroy(struct psample_group *group) 154 { 155 psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP); 156 list_del(&group->list); 157 kfree_rcu(group, rcu); 158 } 159 160 static struct psample_group * 161 psample_group_lookup(struct net *net, u32 group_num) 162 { 163 struct psample_group *group; 164 165 list_for_each_entry(group, &psample_groups_list, list) 166 if ((group->group_num == group_num) && (group->net == net)) 167 return group; 168 return NULL; 169 } 170 171 struct psample_group *psample_group_get(struct net *net, u32 group_num) 172 { 173 struct psample_group *group; 174 175 spin_lock_bh(&psample_groups_lock); 176 177 group = psample_group_lookup(net, group_num); 178 if (!group) { 179 group = psample_group_create(net, group_num); 180 if (!group) 181 goto out; 182 } 183 group->refcount++; 184 185 out: 186 spin_unlock_bh(&psample_groups_lock); 187 return group; 188 } 189 EXPORT_SYMBOL_GPL(psample_group_get); 190 191 void psample_group_take(struct psample_group *group) 192 { 193 spin_lock_bh(&psample_groups_lock); 194 group->refcount++; 195 spin_unlock_bh(&psample_groups_lock); 196 } 197 EXPORT_SYMBOL_GPL(psample_group_take); 198 199 void psample_group_put(struct psample_group *group) 200 { 201 spin_lock_bh(&psample_groups_lock); 202 203 if (--group->refcount == 0) 204 psample_group_destroy(group); 205 206 spin_unlock_bh(&psample_groups_lock); 207 } 208 EXPORT_SYMBOL_GPL(psample_group_put); 209 210 void psample_sample_packet(struct psample_group *group, struct sk_buff *skb, 211 u32 trunc_size, int in_ifindex, int out_ifindex, 212 u32 sample_rate) 213 { 214 struct sk_buff *nl_skb; 215 int data_len; 216 int meta_len; 217 void *data; 218 int ret; 219 220 meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) + 221 (out_ifindex ? nla_total_size(sizeof(u16)) : 0) + 222 nla_total_size(sizeof(u32)) + /* sample_rate */ 223 nla_total_size(sizeof(u32)) + /* orig_size */ 224 nla_total_size(sizeof(u32)) + /* group_num */ 225 nla_total_size(sizeof(u32)); /* seq */ 226 227 data_len = min(skb->len, trunc_size); 228 if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE) 229 data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN 230 - NLA_ALIGNTO; 231 232 nl_skb = genlmsg_new(meta_len + data_len, GFP_ATOMIC); 233 if (unlikely(!nl_skb)) 234 return; 235 236 data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0, 237 PSAMPLE_CMD_SAMPLE); 238 if (unlikely(!data)) 239 goto error; 240 241 if (in_ifindex) { 242 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex); 243 if (unlikely(ret < 0)) 244 goto error; 245 } 246 247 if (out_ifindex) { 248 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex); 249 if (unlikely(ret < 0)) 250 goto error; 251 } 252 253 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate); 254 if (unlikely(ret < 0)) 255 goto error; 256 257 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len); 258 if (unlikely(ret < 0)) 259 goto error; 260 261 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); 262 if (unlikely(ret < 0)) 263 goto error; 264 265 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++); 266 if (unlikely(ret < 0)) 267 goto error; 268 269 if (data_len) { 270 int nla_len = nla_total_size(data_len); 271 struct nlattr *nla; 272 273 nla = skb_put(nl_skb, nla_len); 274 nla->nla_type = PSAMPLE_ATTR_DATA; 275 nla->nla_len = nla_attr_size(data_len); 276 277 if (skb_copy_bits(skb, 0, nla_data(nla), data_len)) 278 goto error; 279 } 280 281 genlmsg_end(nl_skb, data); 282 genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0, 283 PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC); 284 285 return; 286 error: 287 pr_err_ratelimited("Could not create psample log message\n"); 288 nlmsg_free(nl_skb); 289 } 290 EXPORT_SYMBOL_GPL(psample_sample_packet); 291 292 static int __init psample_module_init(void) 293 { 294 return genl_register_family(&psample_nl_family); 295 } 296 297 static void __exit psample_module_exit(void) 298 { 299 genl_unregister_family(&psample_nl_family); 300 } 301 302 module_init(psample_module_init); 303 module_exit(psample_module_exit); 304 305 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>"); 306 MODULE_DESCRIPTION("netlink channel for packet sampling"); 307 MODULE_LICENSE("GPL v2"); 308