/* Netfilter messages via netlink socket. Allows for user space * protocol helpers and general trouble making from userspace. * * (C) 2001 by Jay Schulist , * (C) 2002-2005 by Harald Welte * (C) 2005-2017 by Pablo Neira Ayuso * * Initial netfilter messages via netlink development funded and * generally made possible by Network Robots, Inc. (www.networkrobots.com) * * Further development of this code funded by Astaro AG (http://www.astaro.com) * * This software may be used and distributed according to the terms * of the GNU General Public License, incorporated herein by reference. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include MODULE_LICENSE("GPL"); MODULE_AUTHOR("Harald Welte "); MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); #define nfnl_dereference_protected(id) \ rcu_dereference_protected(table[(id)].subsys, \ lockdep_nfnl_is_held((id))) #define NFNL_MAX_ATTR_COUNT 32 static struct { struct mutex mutex; const struct nfnetlink_subsystem __rcu *subsys; } table[NFNL_SUBSYS_COUNT]; static const int nfnl_group2type[NFNLGRP_MAX+1] = { [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK, [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK, [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK, [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP, [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP, [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP, [NFNLGRP_NFTABLES] = NFNL_SUBSYS_NFTABLES, [NFNLGRP_ACCT_QUOTA] = NFNL_SUBSYS_ACCT, [NFNLGRP_NFTRACE] = NFNL_SUBSYS_NFTABLES, }; void nfnl_lock(__u8 subsys_id) { mutex_lock(&table[subsys_id].mutex); } EXPORT_SYMBOL_GPL(nfnl_lock); void nfnl_unlock(__u8 subsys_id) { mutex_unlock(&table[subsys_id].mutex); } EXPORT_SYMBOL_GPL(nfnl_unlock); #ifdef CONFIG_PROVE_LOCKING bool lockdep_nfnl_is_held(u8 subsys_id) { return lockdep_is_held(&table[subsys_id].mutex); } EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held); #endif int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) { u8 cb_id; /* Sanity-check attr_count size to avoid stack buffer overflow. */ for (cb_id = 0; cb_id < n->cb_count; cb_id++) if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT)) return -EINVAL; nfnl_lock(n->subsys_id); if (table[n->subsys_id].subsys) { nfnl_unlock(n->subsys_id); return -EBUSY; } rcu_assign_pointer(table[n->subsys_id].subsys, n); nfnl_unlock(n->subsys_id); return 0; } EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) { nfnl_lock(n->subsys_id); table[n->subsys_id].subsys = NULL; nfnl_unlock(n->subsys_id); synchronize_rcu(); return 0; } EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type) { u8 subsys_id = NFNL_SUBSYS_ID(type); if (subsys_id >= NFNL_SUBSYS_COUNT) return NULL; return rcu_dereference(table[subsys_id].subsys); } static inline const struct nfnl_callback * nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss) { u8 cb_id = NFNL_MSG_TYPE(type); if (cb_id >= ss->cb_count) return NULL; return &ss->cb[cb_id]; } int nfnetlink_has_listeners(struct net *net, unsigned int group) { return netlink_has_listeners(net->nfnl, group); } EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid, unsigned int group, int echo, gfp_t flags) { return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags); } EXPORT_SYMBOL_GPL(nfnetlink_send); int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error) { return netlink_set_err(net->nfnl, portid, group, error); } EXPORT_SYMBOL_GPL(nfnetlink_set_err); int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid, int flags) { return netlink_unicast(net->nfnl, skb, portid, flags); } EXPORT_SYMBOL_GPL(nfnetlink_unicast); /* Process one complete nfnetlink message. */ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, struct netlink_ext_ack *extack) { struct net *net = sock_net(skb->sk); const struct nfnl_callback *nc; const struct nfnetlink_subsystem *ss; int type, err; /* All the messages must at least contain nfgenmsg */ if (nlmsg_len(nlh) < sizeof(struct nfgenmsg)) return 0; type = nlh->nlmsg_type; replay: rcu_read_lock(); ss = nfnetlink_get_subsys(type); if (!ss) { #ifdef CONFIG_MODULES rcu_read_unlock(); request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); rcu_read_lock(); ss = nfnetlink_get_subsys(type); if (!ss) #endif { rcu_read_unlock(); return -EINVAL; } } nc = nfnetlink_find_client(type, ss); if (!nc) { rcu_read_unlock(); return -EINVAL; } { int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1]; struct nlattr *attr = (void *)nlh + min_len; int attrlen = nlh->nlmsg_len - min_len; __u8 subsys_id = NFNL_SUBSYS_ID(type); /* Sanity-check NFNL_MAX_ATTR_COUNT */ if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) { rcu_read_unlock(); return -ENOMEM; } err = nla_parse(cda, ss->cb[cb_id].attr_count, attr, attrlen, ss->cb[cb_id].policy, extack); if (err < 0) { rcu_read_unlock(); return err; } if (nc->call_rcu) { err = nc->call_rcu(net, net->nfnl, skb, nlh, (const struct nlattr **)cda, extack); rcu_read_unlock(); } else { rcu_read_unlock(); nfnl_lock(subsys_id); if (nfnl_dereference_protected(subsys_id) != ss || nfnetlink_find_client(type, ss) != nc) err = -EAGAIN; else if (nc->call) err = nc->call(net, net->nfnl, skb, nlh, (const struct nlattr **)cda, extack); else err = -EINVAL; nfnl_unlock(subsys_id); } if (err == -EAGAIN) goto replay; return err; } } struct nfnl_err { struct list_head head; struct nlmsghdr *nlh; int err; struct netlink_ext_ack extack; }; static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err, const struct netlink_ext_ack *extack) { struct nfnl_err *nfnl_err; nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL); if (nfnl_err == NULL) return -ENOMEM; nfnl_err->nlh = nlh; nfnl_err->err = err; nfnl_err->extack = *extack; list_add_tail(&nfnl_err->head, list); return 0; } static void nfnl_err_del(struct nfnl_err *nfnl_err) { list_del(&nfnl_err->head); kfree(nfnl_err); } static void nfnl_err_reset(struct list_head *err_list) { struct nfnl_err *nfnl_err, *next; list_for_each_entry_safe(nfnl_err, next, err_list, head) nfnl_err_del(nfnl_err); } static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb) { struct nfnl_err *nfnl_err, *next; list_for_each_entry_safe(nfnl_err, next, err_list, head) { netlink_ack(skb, nfnl_err->nlh, nfnl_err->err, &nfnl_err->extack); nfnl_err_del(nfnl_err); } } enum { NFNL_BATCH_FAILURE = (1 << 0), NFNL_BATCH_DONE = (1 << 1), NFNL_BATCH_REPLAY = (1 << 2), }; static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh, u16 subsys_id, u32 genid) { struct sk_buff *oskb = skb; struct net *net = sock_net(skb->sk); const struct nfnetlink_subsystem *ss; const struct nfnl_callback *nc; struct netlink_ext_ack extack; LIST_HEAD(err_list); u32 status; int err; if (subsys_id >= NFNL_SUBSYS_COUNT) return netlink_ack(skb, nlh, -EINVAL, NULL); replay: status = 0; skb = netlink_skb_clone(oskb, GFP_KERNEL); if (!skb) return netlink_ack(oskb, nlh, -ENOMEM, NULL); nfnl_lock(subsys_id); ss = nfnl_dereference_protected(subsys_id); if (!ss) { #ifdef CONFIG_MODULES nfnl_unlock(subsys_id); request_module("nfnetlink-subsys-%d", subsys_id); nfnl_lock(subsys_id); ss = nfnl_dereference_protected(subsys_id); if (!ss) #endif { nfnl_unlock(subsys_id); netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL); return kfree_skb(skb); } } if (!ss->valid_genid || !ss->commit || !ss->abort) { nfnl_unlock(subsys_id); netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL); return kfree_skb(skb); } if (!try_module_get(ss->owner)) { nfnl_unlock(subsys_id); netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL); return kfree_skb(skb); } if (!ss->valid_genid(net, genid)) { module_put(ss->owner); nfnl_unlock(subsys_id); netlink_ack(oskb, nlh, -ERESTART, NULL); return kfree_skb(skb); } nfnl_unlock(subsys_id); while (skb->len >= nlmsg_total_size(0)) { int msglen, type; if (fatal_signal_pending(current)) { nfnl_err_reset(&err_list); err = -EINTR; status = NFNL_BATCH_FAILURE; goto done; } memset(&extack, 0, sizeof(extack)); nlh = nlmsg_hdr(skb); err = 0; if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len || nlmsg_len(nlh) < sizeof(struct nfgenmsg)) { nfnl_err_reset(&err_list); status |= NFNL_BATCH_FAILURE; goto done; } /* Only requests are handled by the kernel */ if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) { err = -EINVAL; goto ack; } type = nlh->nlmsg_type; if (type == NFNL_MSG_BATCH_BEGIN) { /* Malformed: Batch begin twice */ nfnl_err_reset(&err_list); status |= NFNL_BATCH_FAILURE; goto done; } else if (type == NFNL_MSG_BATCH_END) { status |= NFNL_BATCH_DONE; goto done; } else if (type < NLMSG_MIN_TYPE) { err = -EINVAL; goto ack; } /* We only accept a batch with messages for the same * subsystem. */ if (NFNL_SUBSYS_ID(type) != subsys_id) { err = -EINVAL; goto ack; } nc = nfnetlink_find_client(type, ss); if (!nc) { err = -EINVAL; goto ack; } { int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1]; struct nlattr *attr = (void *)nlh + min_len; int attrlen = nlh->nlmsg_len - min_len; /* Sanity-check NFTA_MAX_ATTR */ if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) { err = -ENOMEM; goto ack; } err = nla_parse(cda, ss->cb[cb_id].attr_count, attr, attrlen, ss->cb[cb_id].policy, NULL); if (err < 0) goto ack; if (nc->call_batch) { err = nc->call_batch(net, net->nfnl, skb, nlh, (const struct nlattr **)cda, &extack); } /* The lock was released to autoload some module, we * have to abort and start from scratch using the * original skb. */ if (err == -EAGAIN) { status |= NFNL_BATCH_REPLAY; goto done; } } ack: if (nlh->nlmsg_flags & NLM_F_ACK || err) { /* Errors are delivered once the full batch has been * processed, this avoids that the same error is * reported several times when replaying the batch. */ if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) { /* We failed to enqueue an error, reset the * list of errors and send OOM to userspace * pointing to the batch header. */ nfnl_err_reset(&err_list); netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM, NULL); status |= NFNL_BATCH_FAILURE; goto done; } /* We don't stop processing the batch on errors, thus, * userspace gets all the errors that the batch * triggers. */ if (err) status |= NFNL_BATCH_FAILURE; } msglen = NLMSG_ALIGN(nlh->nlmsg_len); if (msglen > skb->len) msglen = skb->len; skb_pull(skb, msglen); } done: if (status & NFNL_BATCH_REPLAY) { ss->abort(net, oskb); nfnl_err_reset(&err_list); kfree_skb(skb); module_put(ss->owner); goto replay; } else if (status == NFNL_BATCH_DONE) { err = ss->commit(net, oskb); if (err == -EAGAIN) { status |= NFNL_BATCH_REPLAY; goto done; } else if (err) { ss->abort(net, oskb); netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL); } } else { ss->abort(net, oskb); } if (ss->cleanup) ss->cleanup(net); nfnl_err_deliver(&err_list, oskb); kfree_skb(skb); module_put(ss->owner); } static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = { [NFNL_BATCH_GENID] = { .type = NLA_U32 }, }; static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh) { int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); struct nlattr *attr = (void *)nlh + min_len; struct nlattr *cda[NFNL_BATCH_MAX + 1]; int attrlen = nlh->nlmsg_len - min_len; struct nfgenmsg *nfgenmsg; int msglen, err; u32 gen_id = 0; u16 res_id; msglen = NLMSG_ALIGN(nlh->nlmsg_len); if (msglen > skb->len) msglen = skb->len; if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) return; err = nla_parse(cda, NFNL_BATCH_MAX, attr, attrlen, nfnl_batch_policy, NULL); if (err < 0) { netlink_ack(skb, nlh, err, NULL); return; } if (cda[NFNL_BATCH_GENID]) gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID])); nfgenmsg = nlmsg_data(nlh); skb_pull(skb, msglen); /* Work around old nft using host byte order */ if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES) res_id = NFNL_SUBSYS_NFTABLES; else res_id = ntohs(nfgenmsg->res_id); nfnetlink_rcv_batch(skb, nlh, res_id, gen_id); } static void nfnetlink_rcv(struct sk_buff *skb) { struct nlmsghdr *nlh = nlmsg_hdr(skb); if (skb->len < NLMSG_HDRLEN || nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len) return; if (!netlink_net_capable(skb, CAP_NET_ADMIN)) { netlink_ack(skb, nlh, -EPERM, NULL); return; } if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN) nfnetlink_rcv_skb_batch(skb, nlh); else netlink_rcv_skb(skb, nfnetlink_rcv_msg); } #ifdef CONFIG_MODULES static int nfnetlink_bind(struct net *net, int group) { const struct nfnetlink_subsystem *ss; int type; if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX) return 0; type = nfnl_group2type[group]; rcu_read_lock(); ss = nfnetlink_get_subsys(type << 8); rcu_read_unlock(); if (!ss) request_module_nowait("nfnetlink-subsys-%d", type); return 0; } #endif static int __net_init nfnetlink_net_init(struct net *net) { struct sock *nfnl; struct netlink_kernel_cfg cfg = { .groups = NFNLGRP_MAX, .input = nfnetlink_rcv, #ifdef CONFIG_MODULES .bind = nfnetlink_bind, #endif }; nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg); if (!nfnl) return -ENOMEM; net->nfnl_stash = nfnl; rcu_assign_pointer(net->nfnl, nfnl); return 0; } static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) { struct net *net; list_for_each_entry(net, net_exit_list, exit_list) RCU_INIT_POINTER(net->nfnl, NULL); synchronize_net(); list_for_each_entry(net, net_exit_list, exit_list) netlink_kernel_release(net->nfnl_stash); } static struct pernet_operations nfnetlink_net_ops = { .init = nfnetlink_net_init, .exit_batch = nfnetlink_net_exit_batch, }; static int __init nfnetlink_init(void) { int i; for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++) BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE); for (i=0; i