/* * net/psample/psample.c - Netlink channel for packet sampling * Copyright (c) 2017 Yotam Gigi * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include #include #include #include #include #include #define PSAMPLE_MAX_PACKET_SIZE 0xffff static LIST_HEAD(psample_groups_list); static DEFINE_SPINLOCK(psample_groups_lock); /* multicast groups */ enum psample_nl_multicast_groups { PSAMPLE_NL_MCGRP_CONFIG, PSAMPLE_NL_MCGRP_SAMPLE, }; static const struct genl_multicast_group psample_nl_mcgrps[] = { [PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME }, [PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME }, }; static struct genl_family psample_nl_family; static int psample_group_nl_fill(struct sk_buff *msg, struct psample_group *group, enum psample_command cmd, u32 portid, u32 seq, int flags) { void *hdr; int ret; hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd); if (!hdr) return -EMSGSIZE; ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); if (ret < 0) goto error; ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount); if (ret < 0) goto error; ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq); if (ret < 0) goto error; genlmsg_end(msg, hdr); return 0; error: genlmsg_cancel(msg, hdr); return -EMSGSIZE; } static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg, struct netlink_callback *cb) { struct psample_group *group; int start = cb->args[0]; int idx = 0; int err; spin_lock(&psample_groups_lock); list_for_each_entry(group, &psample_groups_list, list) { if (!net_eq(group->net, sock_net(msg->sk))) continue; if (idx < start) { idx++; continue; } err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq, NLM_F_MULTI); if (err) break; idx++; } spin_unlock(&psample_groups_lock); cb->args[0] = idx; return msg->len; } static const struct genl_ops psample_nl_ops[] = { { .cmd = PSAMPLE_CMD_GET_GROUP, .dumpit = psample_nl_cmd_get_group_dumpit, /* can be retrieved by unprivileged users */ } }; static struct genl_family psample_nl_family = { .name = PSAMPLE_GENL_NAME, .version = PSAMPLE_GENL_VERSION, .maxattr = PSAMPLE_ATTR_MAX, .netnsok = true, .module = THIS_MODULE, .mcgrps = psample_nl_mcgrps, .ops = psample_nl_ops, .n_ops = ARRAY_SIZE(psample_nl_ops), .n_mcgrps = ARRAY_SIZE(psample_nl_mcgrps), }; static void psample_group_notify(struct psample_group *group, enum psample_command cmd) { struct sk_buff *msg; int err; msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); if (!msg) return; err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI); if (!err) genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0, PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC); else nlmsg_free(msg); } static struct psample_group *psample_group_create(struct net *net, u32 group_num) { struct psample_group *group; group = kzalloc(sizeof(*group), GFP_ATOMIC); if (!group) return NULL; group->net = net; group->group_num = group_num; list_add_tail(&group->list, &psample_groups_list); psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP); return group; } static void psample_group_destroy(struct psample_group *group) { psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP); list_del(&group->list); kfree(group); } static struct psample_group * psample_group_lookup(struct net *net, u32 group_num) { struct psample_group *group; list_for_each_entry(group, &psample_groups_list, list) if ((group->group_num == group_num) && (group->net == net)) return group; return NULL; } struct psample_group *psample_group_get(struct net *net, u32 group_num) { struct psample_group *group; spin_lock(&psample_groups_lock); group = psample_group_lookup(net, group_num); if (!group) { group = psample_group_create(net, group_num); if (!group) goto out; } group->refcount++; out: spin_unlock(&psample_groups_lock); return group; } EXPORT_SYMBOL_GPL(psample_group_get); void psample_group_put(struct psample_group *group) { spin_lock(&psample_groups_lock); if (--group->refcount == 0) psample_group_destroy(group); spin_unlock(&psample_groups_lock); } EXPORT_SYMBOL_GPL(psample_group_put); void psample_sample_packet(struct psample_group *group, struct sk_buff *skb, u32 trunc_size, int in_ifindex, int out_ifindex, u32 sample_rate) { struct sk_buff *nl_skb; int data_len; int meta_len; void *data; int ret; meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) + (out_ifindex ? nla_total_size(sizeof(u16)) : 0) + nla_total_size(sizeof(u32)) + /* sample_rate */ nla_total_size(sizeof(u32)) + /* orig_size */ nla_total_size(sizeof(u32)) + /* group_num */ nla_total_size(sizeof(u32)); /* seq */ data_len = min(skb->len, trunc_size); if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE) data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN - NLA_ALIGNTO; nl_skb = genlmsg_new(meta_len + nla_total_size(data_len), GFP_ATOMIC); if (unlikely(!nl_skb)) return; data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0, PSAMPLE_CMD_SAMPLE); if (unlikely(!data)) goto error; if (in_ifindex) { ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex); if (unlikely(ret < 0)) goto error; } if (out_ifindex) { ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex); if (unlikely(ret < 0)) goto error; } ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate); if (unlikely(ret < 0)) goto error; ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len); if (unlikely(ret < 0)) goto error; ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); if (unlikely(ret < 0)) goto error; ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++); if (unlikely(ret < 0)) goto error; if (data_len) { int nla_len = nla_total_size(data_len); struct nlattr *nla; nla = (struct nlattr *)skb_put(nl_skb, nla_len); nla->nla_type = PSAMPLE_ATTR_DATA; nla->nla_len = nla_attr_size(data_len); if (skb_copy_bits(skb, 0, nla_data(nla), data_len)) goto error; } genlmsg_end(nl_skb, data); genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0, PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC); return; error: pr_err_ratelimited("Could not create psample log message\n"); nlmsg_free(nl_skb); } EXPORT_SYMBOL_GPL(psample_sample_packet); static int __init psample_module_init(void) { return genl_register_family(&psample_nl_family); } static void __exit psample_module_exit(void) { genl_unregister_family(&psample_nl_family); } module_init(psample_module_init); module_exit(psample_module_exit); MODULE_AUTHOR("Yotam Gigi "); MODULE_DESCRIPTION("netlink channel for packet sampling"); MODULE_LICENSE("GPL v2");