/* * NETLINK Kernel-user communication protocol. * * Authors: Alan Cox * Alexey Kuznetsov * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith * added netlink_proto_exit * Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo * use nlk_sk, as sk->protinfo is on a diet 8) * Fri Jul 22 19:51:12 MEST 2005 Harald Welte * - inc module use count of module that owns * the kernel socket in case userspace opens * socket of same protocol * - remove all module support, since netlink is * mandatory if CONFIG_NET=y these days */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8) #define NLGRPLONGS(x) (NLGRPSZ(x)/sizeof(unsigned long)) struct netlink_sock { /* struct sock has to be the first member of netlink_sock */ struct sock sk; u32 pid; u32 dst_pid; u32 dst_group; u32 flags; u32 subscriptions; u32 ngroups; unsigned long *groups; unsigned long state; wait_queue_head_t wait; struct netlink_callback *cb; struct mutex *cb_mutex; struct mutex cb_def_mutex; void (*netlink_rcv)(struct sk_buff *skb); struct module *module; }; #define NETLINK_KERNEL_SOCKET 0x1 #define NETLINK_RECV_PKTINFO 0x2 static inline struct netlink_sock *nlk_sk(struct sock *sk) { return container_of(sk, struct netlink_sock, sk); } static inline int netlink_is_kernel(struct sock *sk) { return nlk_sk(sk)->flags & NETLINK_KERNEL_SOCKET; } struct nl_pid_hash { struct hlist_head *table; unsigned long rehash_time; unsigned int mask; unsigned int shift; unsigned int entries; unsigned int max_shift; u32 rnd; }; struct netlink_table { struct nl_pid_hash hash; struct hlist_head mc_list; unsigned long *listeners; unsigned int nl_nonroot; unsigned int groups; struct mutex *cb_mutex; struct module *module; int registered; }; static struct netlink_table *nl_table; static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait); static int netlink_dump(struct sock *sk); static void netlink_destroy_callback(struct netlink_callback *cb); static DEFINE_RWLOCK(nl_table_lock); static atomic_t nl_table_users = ATOMIC_INIT(0); static ATOMIC_NOTIFIER_HEAD(netlink_chain); static u32 netlink_group_mask(u32 group) { return group ? 1 << (group - 1) : 0; } static struct hlist_head *nl_pid_hashfn(struct nl_pid_hash *hash, u32 pid) { return &hash->table[jhash_1word(pid, hash->rnd) & hash->mask]; } static void netlink_sock_destruct(struct sock *sk) { struct netlink_sock *nlk = nlk_sk(sk); if (nlk->cb) { if (nlk->cb->done) nlk->cb->done(nlk->cb); netlink_destroy_callback(nlk->cb); } skb_queue_purge(&sk->sk_receive_queue); if (!sock_flag(sk, SOCK_DEAD)) { printk(KERN_ERR "Freeing alive netlink socket %p\n", sk); return; } BUG_TRAP(!atomic_read(&sk->sk_rmem_alloc)); BUG_TRAP(!atomic_read(&sk->sk_wmem_alloc)); BUG_TRAP(!nlk_sk(sk)->groups); } /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on * SMP. Look, when several writers sleep and reader wakes them up, all but one * immediately hit write lock and grab all the cpus. Exclusive sleep solves * this, _but_ remember, it adds useless work on UP machines. */ static void netlink_table_grab(void) __acquires(nl_table_lock) { write_lock_irq(&nl_table_lock); if (atomic_read(&nl_table_users)) { DECLARE_WAITQUEUE(wait, current); add_wait_queue_exclusive(&nl_table_wait, &wait); for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (atomic_read(&nl_table_users) == 0) break; write_unlock_irq(&nl_table_lock); schedule(); write_lock_irq(&nl_table_lock); } __set_current_state(TASK_RUNNING); remove_wait_queue(&nl_table_wait, &wait); } } static void netlink_table_ungrab(void) __releases(nl_table_lock) { write_unlock_irq(&nl_table_lock); wake_up(&nl_table_wait); } static inline void netlink_lock_table(void) { /* read_lock() synchronizes us to netlink_table_grab */ read_lock(&nl_table_lock); atomic_inc(&nl_table_users); read_unlock(&nl_table_lock); } static inline void netlink_unlock_table(void) { if (atomic_dec_and_test(&nl_table_users)) wake_up(&nl_table_wait); } static inline struct sock *netlink_lookup(struct net *net, int protocol, u32 pid) { struct nl_pid_hash *hash = &nl_table[protocol].hash; struct hlist_head *head; struct sock *sk; struct hlist_node *node; read_lock(&nl_table_lock); head = nl_pid_hashfn(hash, pid); sk_for_each(sk, node, head) { if ((sk->sk_net == net) && (nlk_sk(sk)->pid == pid)) { sock_hold(sk); goto found; } } sk = NULL; found: read_unlock(&nl_table_lock); return sk; } static inline struct hlist_head *nl_pid_hash_zalloc(size_t size) { if (size <= PAGE_SIZE) return kzalloc(size, GFP_ATOMIC); else return (struct hlist_head *) __get_free_pages(GFP_ATOMIC | __GFP_ZERO, get_order(size)); } static inline void nl_pid_hash_free(struct hlist_head *table, size_t size) { if (size <= PAGE_SIZE) kfree(table); else free_pages((unsigned long)table, get_order(size)); } static int nl_pid_hash_rehash(struct nl_pid_hash *hash, int grow) { unsigned int omask, mask, shift; size_t osize, size; struct hlist_head *otable, *table; int i; omask = mask = hash->mask; osize = size = (mask + 1) * sizeof(*table); shift = hash->shift; if (grow) { if (++shift > hash->max_shift) return 0; mask = mask * 2 + 1; size *= 2; } table = nl_pid_hash_zalloc(size); if (!table) return 0; otable = hash->table; hash->table = table; hash->mask = mask; hash->shift = shift; get_random_bytes(&hash->rnd, sizeof(hash->rnd)); for (i = 0; i <= omask; i++) { struct sock *sk; struct hlist_node *node, *tmp; sk_for_each_safe(sk, node, tmp, &otable[i]) __sk_add_node(sk, nl_pid_hashfn(hash, nlk_sk(sk)->pid)); } nl_pid_hash_free(otable, osize); hash->rehash_time = jiffies + 10 * 60 * HZ; return 1; } static inline int nl_pid_hash_dilute(struct nl_pid_hash *hash, int len) { int avg = hash->entries >> hash->shift; if (unlikely(avg > 1) && nl_pid_hash_rehash(hash, 1)) return 1; if (unlikely(len > avg) && time_after(jiffies, hash->rehash_time)) { nl_pid_hash_rehash(hash, 0); return 1; } return 0; } static const struct proto_ops netlink_ops; static void netlink_update_listeners(struct sock *sk) { struct netlink_table *tbl = &nl_table[sk->sk_protocol]; struct hlist_node *node; unsigned long mask; unsigned int i; for (i = 0; i < NLGRPLONGS(tbl->groups); i++) { mask = 0; sk_for_each_bound(sk, node, &tbl->mc_list) { if (i < NLGRPLONGS(nlk_sk(sk)->ngroups)) mask |= nlk_sk(sk)->groups[i]; } tbl->listeners[i] = mask; } /* this function is only called with the netlink table "grabbed", which * makes sure updates are visible before bind or setsockopt return. */ } static int netlink_insert(struct sock *sk, struct net *net, u32 pid) { struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash; struct hlist_head *head; int err = -EADDRINUSE; struct sock *osk; struct hlist_node *node; int len; netlink_table_grab(); head = nl_pid_hashfn(hash, pid); len = 0; sk_for_each(osk, node, head) { if ((osk->sk_net == net) && (nlk_sk(osk)->pid == pid)) break; len++; } if (node) goto err; err = -EBUSY; if (nlk_sk(sk)->pid) goto err; err = -ENOMEM; if (BITS_PER_LONG > 32 && unlikely(hash->entries >= UINT_MAX)) goto err; if (len && nl_pid_hash_dilute(hash, len)) head = nl_pid_hashfn(hash, pid); hash->entries++; nlk_sk(sk)->pid = pid; sk_add_node(sk, head); err = 0; err: netlink_table_ungrab(); return err; } static void netlink_remove(struct sock *sk) { netlink_table_grab(); if (sk_del_node_init(sk)) nl_table[sk->sk_protocol].hash.entries--; if (nlk_sk(sk)->subscriptions) __sk_del_bind_node(sk); netlink_table_ungrab(); } static struct proto netlink_proto = { .name = "NETLINK", .owner = THIS_MODULE, .obj_size = sizeof(struct netlink_sock), }; static int __netlink_create(struct net *net, struct socket *sock, struct mutex *cb_mutex, int protocol) { struct sock *sk; struct netlink_sock *nlk; sock->ops = &netlink_ops; sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto); if (!sk) return -ENOMEM; sock_init_data(sock, sk); nlk = nlk_sk(sk); if (cb_mutex) nlk->cb_mutex = cb_mutex; else { nlk->cb_mutex = &nlk->cb_def_mutex; mutex_init(nlk->cb_mutex); } init_waitqueue_head(&nlk->wait); sk->sk_destruct = netlink_sock_destruct; sk->sk_protocol = protocol; return 0; } static int netlink_create(struct net *net, struct socket *sock, int protocol) { struct module *module = NULL; struct mutex *cb_mutex; struct netlink_sock *nlk; int err = 0; sock->state = SS_UNCONNECTED; if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM) return -ESOCKTNOSUPPORT; if (protocol < 0 || protocol >= MAX_LINKS) return -EPROTONOSUPPORT; netlink_lock_table(); #ifdef CONFIG_KMOD if (!nl_table[protocol].registered) { netlink_unlock_table(); request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol); netlink_lock_table(); } #endif if (nl_table[protocol].registered && try_module_get(nl_table[protocol].module)) module = nl_table[protocol].module; cb_mutex = nl_table[protocol].cb_mutex; netlink_unlock_table(); err = __netlink_create(net, sock, cb_mutex, protocol); if (err < 0) goto out_module; nlk = nlk_sk(sock->sk); nlk->module = module; out: return err; out_module: module_put(module); goto out; } static int netlink_release(struct socket *sock) { struct sock *sk = sock->sk; struct netlink_sock *nlk; if (!sk) return 0; netlink_remove(sk); sock_orphan(sk); nlk = nlk_sk(sk); /* * OK. Socket is unlinked, any packets that arrive now * will be purged. */ sock->sk = NULL; wake_up_interruptible_all(&nlk->wait); skb_queue_purge(&sk->sk_write_queue); if (nlk->pid && !nlk->subscriptions) { struct netlink_notify n = { .net = sk->sk_net, .protocol = sk->sk_protocol, .pid = nlk->pid, }; atomic_notifier_call_chain(&netlink_chain, NETLINK_URELEASE, &n); } module_put(nlk->module); netlink_table_grab(); if (netlink_is_kernel(sk)) { BUG_ON(nl_table[sk->sk_protocol].registered == 0); if (--nl_table[sk->sk_protocol].registered == 0) { kfree(nl_table[sk->sk_protocol].listeners); nl_table[sk->sk_protocol].module = NULL; nl_table[sk->sk_protocol].registered = 0; } } else if (nlk->subscriptions) netlink_update_listeners(sk); netlink_table_ungrab(); kfree(nlk->groups); nlk->groups = NULL; sock_put(sk); return 0; } static int netlink_autobind(struct socket *sock) { struct sock *sk = sock->sk; struct net *net = sk->sk_net; struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash; struct hlist_head *head; struct sock *osk; struct hlist_node *node; s32 pid = current->tgid; int err; static s32 rover = -4097; retry: cond_resched(); netlink_table_grab(); head = nl_pid_hashfn(hash, pid); sk_for_each(osk, node, head) { if ((osk->sk_net != net)) continue; if (nlk_sk(osk)->pid == pid) { /* Bind collision, search negative pid values. */ pid = rover--; if (rover > -4097) rover = -4097; netlink_table_ungrab(); goto retry; } } netlink_table_ungrab(); err = netlink_insert(sk, net, pid); if (err == -EADDRINUSE) goto retry; /* If 2 threads race to autobind, that is fine. */ if (err == -EBUSY) err = 0; return err; } static inline int netlink_capable(struct socket *sock, unsigned int flag) { return (nl_table[sock->sk->sk_protocol].nl_nonroot & flag) || capable(CAP_NET_ADMIN); } static void netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions) { struct netlink_sock *nlk = nlk_sk(sk); if (nlk->subscriptions && !subscriptions) __sk_del_bind_node(sk); else if (!nlk->subscriptions && subscriptions) sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list); nlk->subscriptions = subscriptions; } static int netlink_realloc_groups(struct sock *sk) { struct netlink_sock *nlk = nlk_sk(sk); unsigned int groups; unsigned long *new_groups; int err = 0; netlink_table_grab(); groups = nl_table[sk->sk_protocol].groups; if (!nl_table[sk->sk_protocol].registered) { err = -ENOENT; goto out_unlock; } if (nlk->ngroups >= groups) goto out_unlock; new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC); if (new_groups == NULL) { err = -ENOMEM; goto out_unlock; } memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0, NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups)); nlk->groups = new_groups; nlk->ngroups = groups; out_unlock: netlink_table_ungrab(); return err; } static int netlink_bind(struct socket *sock, struct sockaddr *addr, int addr_len) { struct sock *sk = sock->sk; struct net *net = sk->sk_net; struct netlink_sock *nlk = nlk_sk(sk); struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr; int err; if (nladdr->nl_family != AF_NETLINK) return -EINVAL; /* Only superuser is allowed to listen multicasts */ if (nladdr->nl_groups) { if (!netlink_capable(sock, NL_NONROOT_RECV)) return -EPERM; err = netlink_realloc_groups(sk); if (err) return err; } if (nlk->pid) { if (nladdr->nl_pid != nlk->pid) return -EINVAL; } else { err = nladdr->nl_pid ? netlink_insert(sk, net, nladdr->nl_pid) : netlink_autobind(sock); if (err) return err; } if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0])) return 0; netlink_table_grab(); netlink_update_subscriptions(sk, nlk->subscriptions + hweight32(nladdr->nl_groups) - hweight32(nlk->groups[0])); nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups; netlink_update_listeners(sk); netlink_table_ungrab(); return 0; } static int netlink_connect(struct socket *sock, struct sockaddr *addr, int alen, int flags) { int err = 0; struct sock *sk = sock->sk; struct netlink_sock *nlk = nlk_sk(sk); struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr; if (addr->sa_family == AF_UNSPEC) { sk->sk_state = NETLINK_UNCONNECTED; nlk->dst_pid = 0; nlk->dst_group = 0; return 0; } if (addr->sa_family != AF_NETLINK) return -EINVAL; /* Only superuser is allowed to send multicasts */ if (nladdr->nl_groups && !netlink_capable(sock, NL_NONROOT_SEND)) return -EPERM; if (!nlk->pid) err = netlink_autobind(sock); if (err == 0) { sk->sk_state = NETLINK_CONNECTED; nlk->dst_pid = nladdr->nl_pid; nlk->dst_group = ffs(nladdr->nl_groups); } return err; } static int netlink_getname(struct socket *sock, struct sockaddr *addr, int *addr_len, int peer) { struct sock *sk = sock->sk; struct netlink_sock *nlk = nlk_sk(sk); struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr; nladdr->nl_family = AF_NETLINK; nladdr->nl_pad = 0; *addr_len = sizeof(*nladdr); if (peer) { nladdr->nl_pid = nlk->dst_pid; nladdr->nl_groups = netlink_group_mask(nlk->dst_group); } else { nladdr->nl_pid = nlk->pid; nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0; } return 0; } static void netlink_overrun(struct sock *sk) { if (!test_and_set_bit(0, &nlk_sk(sk)->state)) { sk->sk_err = ENOBUFS; sk->sk_error_report(sk); } } static struct sock *netlink_getsockbypid(struct sock *ssk, u32 pid) { struct sock *sock; struct netlink_sock *nlk; sock = netlink_lookup(ssk->sk_net, ssk->sk_protocol, pid); if (!sock) return ERR_PTR(-ECONNREFUSED); /* Don't bother queuing skb if kernel socket has no input function */ nlk = nlk_sk(sock); if (sock->sk_state == NETLINK_CONNECTED && nlk->dst_pid != nlk_sk(ssk)->pid) { sock_put(sock); return ERR_PTR(-ECONNREFUSED); } return sock; } struct sock *netlink_getsockbyfilp(struct file *filp) { struct inode *inode = filp->f_path.dentry->d_inode; struct sock *sock; if (!S_ISSOCK(inode->i_mode)) return ERR_PTR(-ENOTSOCK); sock = SOCKET_I(inode)->sk; if (sock->sk_family != AF_NETLINK) return ERR_PTR(-EINVAL); sock_hold(sock); return sock; } /* * Attach a skb to a netlink socket. * The caller must hold a reference to the destination socket. On error, the * reference is dropped. The skb is not send to the destination, just all * all error checks are performed and memory in the queue is reserved. * Return values: * < 0: error. skb freed, reference to sock dropped. * 0: continue * 1: repeat lookup - reference dropped while waiting for socket memory. */ int netlink_attachskb(struct sock *sk, struct sk_buff *skb, int nonblock, long *timeo, struct sock *ssk) { struct netlink_sock *nlk; nlk = nlk_sk(sk); if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf || test_bit(0, &nlk->state)) { DECLARE_WAITQUEUE(wait, current); if (!*timeo) { if (!ssk || netlink_is_kernel(ssk)) netlink_overrun(sk); sock_put(sk); kfree_skb(skb); return -EAGAIN; } __set_current_state(TASK_INTERRUPTIBLE); add_wait_queue(&nlk->wait, &wait); if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf || test_bit(0, &nlk->state)) && !sock_flag(sk, SOCK_DEAD)) *timeo = schedule_timeout(*timeo); __set_current_state(TASK_RUNNING); remove_wait_queue(&nlk->wait, &wait); sock_put(sk); if (signal_pending(current)) { kfree_skb(skb); return sock_intr_errno(*timeo); } return 1; } skb_set_owner_r(skb, sk); return 0; } int netlink_sendskb(struct sock *sk, struct sk_buff *skb) { int len = skb->len; skb_queue_tail(&sk->sk_receive_queue, skb); sk->sk_data_ready(sk, len); sock_put(sk); return len; } void netlink_detachskb(struct sock *sk, struct sk_buff *skb) { kfree_skb(skb); sock_put(sk); } static inline struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation) { int delta; skb_orphan(skb); delta = skb->end - skb->tail; if (delta * 2 < skb->truesize) return skb; if (skb_shared(skb)) { struct sk_buff *nskb = skb_clone(skb, allocation); if (!nskb) return skb; kfree_skb(skb); skb = nskb; } if (!pskb_expand_head(skb, 0, -delta, allocation)) skb->truesize -= delta; return skb; } static inline void netlink_rcv_wake(struct sock *sk) { struct netlink_sock *nlk = nlk_sk(sk); if (skb_queue_empty(&sk->sk_receive_queue)) clear_bit(0, &nlk->state); if (!test_bit(0, &nlk->state)) wake_up_interruptible(&nlk->wait); } static inline int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb) { int ret; struct netlink_sock *nlk = nlk_sk(sk); ret = -ECONNREFUSED; if (nlk->netlink_rcv != NULL) { ret = skb->len; skb_set_owner_r(skb, sk); nlk->netlink_rcv(skb); } kfree_skb(skb); sock_put(sk); return ret; } int netlink_unicast(struct sock *ssk, struct sk_buff *skb, u32 pid, int nonblock) { struct sock *sk; int err; long timeo; skb = netlink_trim(skb, gfp_any()); timeo = sock_sndtimeo(ssk, nonblock); retry: sk = netlink_getsockbypid(ssk, pid); if (IS_ERR(sk)) { kfree_skb(skb); return PTR_ERR(sk); } if (netlink_is_kernel(sk)) return netlink_unicast_kernel(sk, skb); err = netlink_attachskb(sk, skb, nonblock, &timeo, ssk); if (err == 1) goto retry; if (err) return err; return netlink_sendskb(sk, skb); } EXPORT_SYMBOL(netlink_unicast); int netlink_has_listeners(struct sock *sk, unsigned int group) { int res = 0; unsigned long *listeners; BUG_ON(!netlink_is_kernel(sk)); rcu_read_lock(); listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners); if (group - 1 < nl_table[sk->sk_protocol].groups) res = test_bit(group - 1, listeners); rcu_read_unlock(); return res; } EXPORT_SYMBOL_GPL(netlink_has_listeners); static inline int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb) { struct netlink_sock *nlk = nlk_sk(sk); if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf && !test_bit(0, &nlk->state)) { skb_set_owner_r(skb, sk); skb_queue_tail(&sk->sk_receive_queue, skb); sk->sk_data_ready(sk, skb->len); return atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf; } return -1; } struct netlink_broadcast_data { struct sock *exclude_sk; struct net *net; u32 pid; u32 group; int failure; int congested; int delivered; gfp_t allocation; struct sk_buff *skb, *skb2; }; static inline int do_one_broadcast(struct sock *sk, struct netlink_broadcast_data *p) { struct netlink_sock *nlk = nlk_sk(sk); int val; if (p->exclude_sk == sk) goto out; if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups || !test_bit(p->group - 1, nlk->groups)) goto out; if ((sk->sk_net != p->net)) goto out; if (p->failure) { netlink_overrun(sk); goto out; } sock_hold(sk); if (p->skb2 == NULL) { if (skb_shared(p->skb)) { p->skb2 = skb_clone(p->skb, p->allocation); } else { p->skb2 = skb_get(p->skb); /* * skb ownership may have been set when * delivered to a previous socket. */ skb_orphan(p->skb2); } } if (p->skb2 == NULL) { netlink_overrun(sk); /* Clone failed. Notify ALL listeners. */ p->failure = 1; } else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) { netlink_overrun(sk); } else { p->congested |= val; p->delivered = 1; p->skb2 = NULL; } sock_put(sk); out: return 0; } int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 pid, u32 group, gfp_t allocation) { struct net *net = ssk->sk_net; struct netlink_broadcast_data info; struct hlist_node *node; struct sock *sk; skb = netlink_trim(skb, allocation); info.exclude_sk = ssk; info.net = net; info.pid = pid; info.group = group; info.failure = 0; info.congested = 0; info.delivered = 0; info.allocation = allocation; info.skb = skb; info.skb2 = NULL; /* While we sleep in clone, do not allow to change socket list */ netlink_lock_table(); sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list) do_one_broadcast(sk, &info); kfree_skb(skb); netlink_unlock_table(); if (info.skb2) kfree_skb(info.skb2); if (info.delivered) { if (info.congested && (allocation & __GFP_WAIT)) yield(); return 0; } if (info.failure) return -ENOBUFS; return -ESRCH; } EXPORT_SYMBOL(netlink_broadcast); struct netlink_set_err_data { struct sock *exclude_sk; u32 pid; u32 group; int code; }; static inline int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p) { struct netlink_sock *nlk = nlk_sk(sk); if (sk == p->exclude_sk) goto out; if (sk->sk_net != p->exclude_sk->sk_net) goto out; if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups || !test_bit(p->group - 1, nlk->groups)) goto out; sk->sk_err = p->code; sk->sk_error_report(sk); out: return 0; } void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code) { struct netlink_set_err_data info; struct hlist_node *node; struct sock *sk; info.exclude_sk = ssk; info.pid = pid; info.group = group; info.code = code; read_lock(&nl_table_lock); sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list) do_one_set_err(sk, &info); read_unlock(&nl_table_lock); } /* must be called with netlink table grabbed */ static void netlink_update_socket_mc(struct netlink_sock *nlk, unsigned int group, int is_new) { int old, new = !!is_new, subscriptions; old = test_bit(group - 1, nlk->groups); subscriptions = nlk->subscriptions - old + new; if (new) __set_bit(group - 1, nlk->groups); else __clear_bit(group - 1, nlk->groups); netlink_update_subscriptions(&nlk->sk, subscriptions); netlink_update_listeners(&nlk->sk); } static int netlink_setsockopt(struct socket *sock, int level, int optname, char __user *optval, int optlen) { struct sock *sk = sock->sk; struct netlink_sock *nlk = nlk_sk(sk); unsigned int val = 0; int err; if (level != SOL_NETLINK) return -ENOPROTOOPT; if (optlen >= sizeof(int) && get_user(val, (unsigned int __user *)optval)) return -EFAULT; switch (optname) { case NETLINK_PKTINFO: if (val) nlk->flags |= NETLINK_RECV_PKTINFO; else nlk->flags &= ~NETLINK_RECV_PKTINFO; err = 0; break; case NETLINK_ADD_MEMBERSHIP: case NETLINK_DROP_MEMBERSHIP: { if (!netlink_capable(sock, NL_NONROOT_RECV)) return -EPERM; err = netlink_realloc_groups(sk); if (err) return err; if (!val || val - 1 >= nlk->ngroups) return -EINVAL; netlink_table_grab(); netlink_update_socket_mc(nlk, val, optname == NETLINK_ADD_MEMBERSHIP); netlink_table_ungrab(); err = 0; break; } default: err = -ENOPROTOOPT; } return err; } static int netlink_getsockopt(struct socket *sock, int level, int optname, char __user *optval, int __user *optlen) { struct sock *sk = sock->sk; struct netlink_sock *nlk = nlk_sk(sk); int len, val, err; if (level != SOL_NETLINK) return -ENOPROTOOPT; if (get_user(len, optlen)) return -EFAULT; if (len < 0) return -EINVAL; switch (optname) { case NETLINK_PKTINFO: if (len < sizeof(int)) return -EINVAL; len = sizeof(int); val = nlk->flags & NETLINK_RECV_PKTINFO ? 1 : 0; if (put_user(len, optlen) || put_user(val, optval)) return -EFAULT; err = 0; break; default: err = -ENOPROTOOPT; } return err; } static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb) { struct nl_pktinfo info; info.group = NETLINK_CB(skb).dst_group; put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info); } static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock, struct msghdr *msg, size_t len) { struct sock_iocb *siocb = kiocb_to_siocb(kiocb); struct sock *sk = sock->sk; struct netlink_sock *nlk = nlk_sk(sk); struct sockaddr_nl *addr = msg->msg_name; u32 dst_pid; u32 dst_group; struct sk_buff *skb; int err; struct scm_cookie scm; if (msg->msg_flags&MSG_OOB) return -EOPNOTSUPP; if (NULL == siocb->scm) siocb->scm = &scm; err = scm_send(sock, msg, siocb->scm); if (err < 0) return err; if (msg->msg_namelen) { if (addr->nl_family != AF_NETLINK) return -EINVAL; dst_pid = addr->nl_pid; dst_group = ffs(addr->nl_groups); if (dst_group && !netlink_capable(sock, NL_NONROOT_SEND)) return -EPERM; } else { dst_pid = nlk->dst_pid; dst_group = nlk->dst_group; } if (!nlk->pid) { err = netlink_autobind(sock); if (err) goto out; } err = -EMSGSIZE; if (len > sk->sk_sndbuf - 32) goto out; err = -ENOBUFS; skb = alloc_skb(len, GFP_KERNEL); if (skb == NULL) goto out; NETLINK_CB(skb).pid = nlk->pid; NETLINK_CB(skb).dst_group = dst_group; NETLINK_CB(skb).loginuid = audit_get_loginuid(current->audit_context); selinux_get_task_sid(current, &(NETLINK_CB(skb).sid)); memcpy(NETLINK_CREDS(skb), &siocb->scm->creds, sizeof(struct ucred)); /* What can I do? Netlink is asynchronous, so that we will have to save current capabilities to check them, when this message will be delivered to corresponding kernel module. --ANK (980802) */ err = -EFAULT; if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) { kfree_skb(skb); goto out; } err = security_netlink_send(sk, skb); if (err) { kfree_skb(skb); goto out; } if (dst_group) { atomic_inc(&skb->users); netlink_broadcast(sk, skb, dst_pid, dst_group, GFP_KERNEL); } err = netlink_unicast(sk, skb, dst_pid, msg->msg_flags&MSG_DONTWAIT); out: return err; } static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock, struct msghdr *msg, size_t len, int flags) { struct sock_iocb *siocb = kiocb_to_siocb(kiocb); struct scm_cookie scm; struct sock *sk = sock->sk; struct netlink_sock *nlk = nlk_sk(sk); int noblock = flags&MSG_DONTWAIT; size_t copied; struct sk_buff *skb; int err; if (flags&MSG_OOB) return -EOPNOTSUPP; copied = 0; skb = skb_recv_datagram(sk, flags, noblock, &err); if (skb == NULL) goto out; msg->msg_namelen = 0; copied = skb->len; if (len < copied) { msg->msg_flags |= MSG_TRUNC; copied = len; } skb_reset_transport_header(skb); err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied); if (msg->msg_name) { struct sockaddr_nl *addr = (struct sockaddr_nl *)msg->msg_name; addr->nl_family = AF_NETLINK; addr->nl_pad = 0; addr->nl_pid = NETLINK_CB(skb).pid; addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group); msg->msg_namelen = sizeof(*addr); } if (nlk->flags & NETLINK_RECV_PKTINFO) netlink_cmsg_recv_pktinfo(msg, skb); if (NULL == siocb->scm) { memset(&scm, 0, sizeof(scm)); siocb->scm = &scm; } siocb->scm->creds = *NETLINK_CREDS(skb); if (flags & MSG_TRUNC) copied = skb->len; skb_free_datagram(sk, skb); if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) netlink_dump(sk); scm_recv(sock, msg, siocb->scm, flags); out: netlink_rcv_wake(sk); return err ? : copied; } static void netlink_data_ready(struct sock *sk, int len) { BUG(); } /* * We export these functions to other modules. They provide a * complete set of kernel non-blocking support for message * queueing. */ struct sock * netlink_kernel_create(struct net *net, int unit, unsigned int groups, void (*input)(struct sk_buff *skb), struct mutex *cb_mutex, struct module *module) { struct socket *sock; struct sock *sk; struct netlink_sock *nlk; unsigned long *listeners = NULL; BUG_ON(!nl_table); if (unit < 0 || unit >= MAX_LINKS) return NULL; if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock)) return NULL; if (__netlink_create(net, sock, cb_mutex, unit) < 0) goto out_sock_release; if (groups < 32) groups = 32; listeners = kzalloc(NLGRPSZ(groups), GFP_KERNEL); if (!listeners) goto out_sock_release; sk = sock->sk; sk->sk_data_ready = netlink_data_ready; if (input) nlk_sk(sk)->netlink_rcv = input; if (netlink_insert(sk, net, 0)) goto out_sock_release; nlk = nlk_sk(sk); nlk->flags |= NETLINK_KERNEL_SOCKET; netlink_table_grab(); if (!nl_table[unit].registered) { nl_table[unit].groups = groups; nl_table[unit].listeners = listeners; nl_table[unit].cb_mutex = cb_mutex; nl_table[unit].module = module; nl_table[unit].registered = 1; } else { kfree(listeners); nl_table[unit].registered++; } netlink_table_ungrab(); return sk; out_sock_release: kfree(listeners); sock_release(sock); return NULL; } EXPORT_SYMBOL(netlink_kernel_create); void netlink_kernel_release(struct sock *sk) { if (sk == NULL || sk->sk_socket == NULL) return; sock_release(sk->sk_socket); } EXPORT_SYMBOL(netlink_kernel_release); /** * netlink_change_ngroups - change number of multicast groups * * This changes the number of multicast groups that are available * on a certain netlink family. Note that it is not possible to * change the number of groups to below 32. Also note that it does * not implicitly call netlink_clear_multicast_users() when the * number of groups is reduced. * * @sk: The kernel netlink socket, as returned by netlink_kernel_create(). * @groups: The new number of groups. */ int netlink_change_ngroups(struct sock *sk, unsigned int groups) { unsigned long *listeners, *old = NULL; struct netlink_table *tbl = &nl_table[sk->sk_protocol]; int err = 0; if (groups < 32) groups = 32; netlink_table_grab(); if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) { listeners = kzalloc(NLGRPSZ(groups), GFP_ATOMIC); if (!listeners) { err = -ENOMEM; goto out_ungrab; } old = tbl->listeners; memcpy(listeners, old, NLGRPSZ(tbl->groups)); rcu_assign_pointer(tbl->listeners, listeners); } tbl->groups = groups; out_ungrab: netlink_table_ungrab(); synchronize_rcu(); kfree(old); return err; } EXPORT_SYMBOL(netlink_change_ngroups); /** * netlink_clear_multicast_users - kick off multicast listeners * * This function removes all listeners from the given group. * @ksk: The kernel netlink socket, as returned by * netlink_kernel_create(). * @group: The multicast group to clear. */ void netlink_clear_multicast_users(struct sock *ksk, unsigned int group) { struct sock *sk; struct hlist_node *node; struct netlink_table *tbl = &nl_table[ksk->sk_protocol]; netlink_table_grab(); sk_for_each_bound(sk, node, &tbl->mc_list) netlink_update_socket_mc(nlk_sk(sk), group, 0); netlink_table_ungrab(); } EXPORT_SYMBOL(netlink_clear_multicast_users); void netlink_set_nonroot(int protocol, unsigned int flags) { if ((unsigned int)protocol < MAX_LINKS) nl_table[protocol].nl_nonroot = flags; } EXPORT_SYMBOL(netlink_set_nonroot); static void netlink_destroy_callback(struct netlink_callback *cb) { if (cb->skb) kfree_skb(cb->skb); kfree(cb); } /* * It looks a bit ugly. * It would be better to create kernel thread. */ static int netlink_dump(struct sock *sk) { struct netlink_sock *nlk = nlk_sk(sk); struct netlink_callback *cb; struct sk_buff *skb; struct nlmsghdr *nlh; int len, err = -ENOBUFS; skb = sock_rmalloc(sk, NLMSG_GOODSIZE, 0, GFP_KERNEL); if (!skb) goto errout; mutex_lock(nlk->cb_mutex); cb = nlk->cb; if (cb == NULL) { err = -EINVAL; goto errout_skb; } len = cb->dump(skb, cb); if (len > 0) { mutex_unlock(nlk->cb_mutex); skb_queue_tail(&sk->sk_receive_queue, skb); sk->sk_data_ready(sk, len); return 0; } nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI); if (!nlh) goto errout_skb; memcpy(nlmsg_data(nlh), &len, sizeof(len)); skb_queue_tail(&sk->sk_receive_queue, skb); sk->sk_data_ready(sk, skb->len); if (cb->done) cb->done(cb); nlk->cb = NULL; mutex_unlock(nlk->cb_mutex); netlink_destroy_callback(cb); return 0; errout_skb: mutex_unlock(nlk->cb_mutex); kfree_skb(skb); errout: return err; } int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, struct nlmsghdr *nlh, int (*dump)(struct sk_buff *skb, struct netlink_callback *), int (*done)(struct netlink_callback *)) { struct netlink_callback *cb; struct sock *sk; struct netlink_sock *nlk; cb = kzalloc(sizeof(*cb), GFP_KERNEL); if (cb == NULL) return -ENOBUFS; cb->dump = dump; cb->done = done; cb->nlh = nlh; atomic_inc(&skb->users); cb->skb = skb; sk = netlink_lookup(ssk->sk_net, ssk->sk_protocol, NETLINK_CB(skb).pid); if (sk == NULL) { netlink_destroy_callback(cb); return -ECONNREFUSED; } nlk = nlk_sk(sk); /* A dump is in progress... */ mutex_lock(nlk->cb_mutex); if (nlk->cb) { mutex_unlock(nlk->cb_mutex); netlink_destroy_callback(cb); sock_put(sk); return -EBUSY; } nlk->cb = cb; mutex_unlock(nlk->cb_mutex); netlink_dump(sk); sock_put(sk); /* We successfully started a dump, by returning -EINTR we * signal not to send ACK even if it was requested. */ return -EINTR; } EXPORT_SYMBOL(netlink_dump_start); void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err) { struct sk_buff *skb; struct nlmsghdr *rep; struct nlmsgerr *errmsg; size_t payload = sizeof(*errmsg); /* error messages get the original request appened */ if (err) payload += nlmsg_len(nlh); skb = nlmsg_new(payload, GFP_KERNEL); if (!skb) { struct sock *sk; sk = netlink_lookup(in_skb->sk->sk_net, in_skb->sk->sk_protocol, NETLINK_CB(in_skb).pid); if (sk) { sk->sk_err = ENOBUFS; sk->sk_error_report(sk); sock_put(sk); } return; } rep = __nlmsg_put(skb, NETLINK_CB(in_skb).pid, nlh->nlmsg_seq, NLMSG_ERROR, sizeof(struct nlmsgerr), 0); errmsg = nlmsg_data(rep); errmsg->error = err; memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh)); netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).pid, MSG_DONTWAIT); } EXPORT_SYMBOL(netlink_ack); int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *, struct nlmsghdr *)) { struct nlmsghdr *nlh; int err; while (skb->len >= nlmsg_total_size(0)) { int msglen; nlh = nlmsg_hdr(skb); err = 0; if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len) return 0; /* Only requests are handled by the kernel */ if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) goto ack; /* Skip control messages */ if (nlh->nlmsg_type < NLMSG_MIN_TYPE) goto ack; err = cb(skb, nlh); if (err == -EINTR) goto skip; ack: if (nlh->nlmsg_flags & NLM_F_ACK || err) netlink_ack(skb, nlh, err); skip: msglen = NLMSG_ALIGN(nlh->nlmsg_len); if (msglen > skb->len) msglen = skb->len; skb_pull(skb, msglen); } return 0; } EXPORT_SYMBOL(netlink_rcv_skb); /** * nlmsg_notify - send a notification netlink message * @sk: netlink socket to use * @skb: notification message * @pid: destination netlink pid for reports or 0 * @group: destination multicast group or 0 * @report: 1 to report back, 0 to disable * @flags: allocation flags */ int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 pid, unsigned int group, int report, gfp_t flags) { int err = 0; if (group) { int exclude_pid = 0; if (report) { atomic_inc(&skb->users); exclude_pid = pid; } /* errors reported via destination sk->sk_err */ nlmsg_multicast(sk, skb, exclude_pid, group, flags); } if (report) err = nlmsg_unicast(sk, skb, pid); return err; } EXPORT_SYMBOL(nlmsg_notify); #ifdef CONFIG_PROC_FS struct nl_seq_iter { struct seq_net_private p; int link; int hash_idx; }; static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos) { struct nl_seq_iter *iter = seq->private; int i, j; struct sock *s; struct hlist_node *node; loff_t off = 0; for (i = 0; i < MAX_LINKS; i++) { struct nl_pid_hash *hash = &nl_table[i].hash; for (j = 0; j <= hash->mask; j++) { sk_for_each(s, node, &hash->table[j]) { if (iter->p.net != s->sk_net) continue; if (off == pos) { iter->link = i; iter->hash_idx = j; return s; } ++off; } } } return NULL; } static void *netlink_seq_start(struct seq_file *seq, loff_t *pos) __acquires(nl_table_lock) { read_lock(&nl_table_lock); return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN; } static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos) { struct sock *s; struct nl_seq_iter *iter; int i, j; ++*pos; if (v == SEQ_START_TOKEN) return netlink_seq_socket_idx(seq, 0); iter = seq->private; s = v; do { s = sk_next(s); } while (s && (iter->p.net != s->sk_net)); if (s) return s; i = iter->link; j = iter->hash_idx + 1; do { struct nl_pid_hash *hash = &nl_table[i].hash; for (; j <= hash->mask; j++) { s = sk_head(&hash->table[j]); while (s && (iter->p.net != s->sk_net)) s = sk_next(s); if (s) { iter->link = i; iter->hash_idx = j; return s; } } j = 0; } while (++i < MAX_LINKS); return NULL; } static void netlink_seq_stop(struct seq_file *seq, void *v) __releases(nl_table_lock) { read_unlock(&nl_table_lock); } static int netlink_seq_show(struct seq_file *seq, void *v) { if (v == SEQ_START_TOKEN) seq_puts(seq, "sk Eth Pid Groups " "Rmem Wmem Dump Locks\n"); else { struct sock *s = v; struct netlink_sock *nlk = nlk_sk(s); seq_printf(seq, "%p %-3d %-6d %08x %-8d %-8d %p %d\n", s, s->sk_protocol, nlk->pid, nlk->groups ? (u32)nlk->groups[0] : 0, atomic_read(&s->sk_rmem_alloc), atomic_read(&s->sk_wmem_alloc), nlk->cb, atomic_read(&s->sk_refcnt) ); } return 0; } static const struct seq_operations netlink_seq_ops = { .start = netlink_seq_start, .next = netlink_seq_next, .stop = netlink_seq_stop, .show = netlink_seq_show, }; static int netlink_seq_open(struct inode *inode, struct file *file) { return seq_open_net(inode, file, &netlink_seq_ops, sizeof(struct nl_seq_iter)); } static const struct file_operations netlink_seq_fops = { .owner = THIS_MODULE, .open = netlink_seq_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release_net, }; #endif int netlink_register_notifier(struct notifier_block *nb) { return atomic_notifier_chain_register(&netlink_chain, nb); } EXPORT_SYMBOL(netlink_register_notifier); int netlink_unregister_notifier(struct notifier_block *nb) { return atomic_notifier_chain_unregister(&netlink_chain, nb); } EXPORT_SYMBOL(netlink_unregister_notifier); static const struct proto_ops netlink_ops = { .family = PF_NETLINK, .owner = THIS_MODULE, .release = netlink_release, .bind = netlink_bind, .connect = netlink_connect, .socketpair = sock_no_socketpair, .accept = sock_no_accept, .getname = netlink_getname, .poll = datagram_poll, .ioctl = sock_no_ioctl, .listen = sock_no_listen, .shutdown = sock_no_shutdown, .setsockopt = netlink_setsockopt, .getsockopt = netlink_getsockopt, .sendmsg = netlink_sendmsg, .recvmsg = netlink_recvmsg, .mmap = sock_no_mmap, .sendpage = sock_no_sendpage, }; static struct net_proto_family netlink_family_ops = { .family = PF_NETLINK, .create = netlink_create, .owner = THIS_MODULE, /* for consistency 8) */ }; static int __net_init netlink_net_init(struct net *net) { #ifdef CONFIG_PROC_FS if (!proc_net_fops_create(net, "netlink", 0, &netlink_seq_fops)) return -ENOMEM; #endif return 0; } static void __net_exit netlink_net_exit(struct net *net) { #ifdef CONFIG_PROC_FS proc_net_remove(net, "netlink"); #endif } static struct pernet_operations __net_initdata netlink_net_ops = { .init = netlink_net_init, .exit = netlink_net_exit, }; static int __init netlink_proto_init(void) { struct sk_buff *dummy_skb; int i; unsigned long limit; unsigned int order; int err = proto_register(&netlink_proto, 0); if (err != 0) goto out; BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > sizeof(dummy_skb->cb)); nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL); if (!nl_table) goto panic; if (num_physpages >= (128 * 1024)) limit = num_physpages >> (21 - PAGE_SHIFT); else limit = num_physpages >> (23 - PAGE_SHIFT); order = get_bitmask_order(limit) - 1 + PAGE_SHIFT; limit = (1UL << order) / sizeof(struct hlist_head); order = get_bitmask_order(min(limit, (unsigned long)UINT_MAX)) - 1; for (i = 0; i < MAX_LINKS; i++) { struct nl_pid_hash *hash = &nl_table[i].hash; hash->table = nl_pid_hash_zalloc(1 * sizeof(*hash->table)); if (!hash->table) { while (i-- > 0) nl_pid_hash_free(nl_table[i].hash.table, 1 * sizeof(*hash->table)); kfree(nl_table); goto panic; } hash->max_shift = order; hash->shift = 0; hash->mask = 0; hash->rehash_time = jiffies; } sock_register(&netlink_family_ops); register_pernet_subsys(&netlink_net_ops); /* The netlink device handler may be needed early. */ rtnetlink_init(); out: return err; panic: panic("netlink_init: Cannot allocate nl_table\n"); } core_initcall(netlink_proto_init);