374 строки
8.3 KiB
C
374 строки
8.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/bpf.h>
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#include <linux/filter.h>
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#include <net/net_namespace.h>
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/*
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* Functions to manage BPF programs attached to netns
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*/
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struct bpf_netns_link {
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struct bpf_link link;
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enum bpf_attach_type type;
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enum netns_bpf_attach_type netns_type;
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/* We don't hold a ref to net in order to auto-detach the link
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* when netns is going away. Instead we rely on pernet
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* pre_exit callback to clear this pointer. Must be accessed
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* with netns_bpf_mutex held.
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*/
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struct net *net;
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};
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/* Protects updates to netns_bpf */
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DEFINE_MUTEX(netns_bpf_mutex);
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/* Must be called with netns_bpf_mutex held. */
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static void __net_exit bpf_netns_link_auto_detach(struct bpf_link *link)
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{
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struct bpf_netns_link *net_link =
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container_of(link, struct bpf_netns_link, link);
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net_link->net = NULL;
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}
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static void bpf_netns_link_release(struct bpf_link *link)
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{
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struct bpf_netns_link *net_link =
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container_of(link, struct bpf_netns_link, link);
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enum netns_bpf_attach_type type = net_link->netns_type;
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struct net *net;
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/* Link auto-detached by dying netns. */
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if (!net_link->net)
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return;
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mutex_lock(&netns_bpf_mutex);
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/* Recheck after potential sleep. We can race with cleanup_net
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* here, but if we see a non-NULL struct net pointer pre_exit
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* has not happened yet and will block on netns_bpf_mutex.
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*/
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net = net_link->net;
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if (!net)
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goto out_unlock;
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net->bpf.links[type] = NULL;
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RCU_INIT_POINTER(net->bpf.progs[type], NULL);
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out_unlock:
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mutex_unlock(&netns_bpf_mutex);
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}
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static void bpf_netns_link_dealloc(struct bpf_link *link)
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{
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struct bpf_netns_link *net_link =
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container_of(link, struct bpf_netns_link, link);
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kfree(net_link);
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}
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static int bpf_netns_link_update_prog(struct bpf_link *link,
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struct bpf_prog *new_prog,
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struct bpf_prog *old_prog)
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{
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struct bpf_netns_link *net_link =
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container_of(link, struct bpf_netns_link, link);
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enum netns_bpf_attach_type type = net_link->netns_type;
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struct net *net;
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int ret = 0;
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if (old_prog && old_prog != link->prog)
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return -EPERM;
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if (new_prog->type != link->prog->type)
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return -EINVAL;
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mutex_lock(&netns_bpf_mutex);
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net = net_link->net;
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if (!net || !check_net(net)) {
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/* Link auto-detached or netns dying */
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ret = -ENOLINK;
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goto out_unlock;
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}
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old_prog = xchg(&link->prog, new_prog);
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rcu_assign_pointer(net->bpf.progs[type], new_prog);
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bpf_prog_put(old_prog);
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out_unlock:
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mutex_unlock(&netns_bpf_mutex);
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return ret;
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}
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static int bpf_netns_link_fill_info(const struct bpf_link *link,
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struct bpf_link_info *info)
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{
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const struct bpf_netns_link *net_link =
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container_of(link, struct bpf_netns_link, link);
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unsigned int inum = 0;
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struct net *net;
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mutex_lock(&netns_bpf_mutex);
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net = net_link->net;
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if (net && check_net(net))
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inum = net->ns.inum;
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mutex_unlock(&netns_bpf_mutex);
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info->netns.netns_ino = inum;
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info->netns.attach_type = net_link->type;
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return 0;
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}
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static void bpf_netns_link_show_fdinfo(const struct bpf_link *link,
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struct seq_file *seq)
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{
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struct bpf_link_info info = {};
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bpf_netns_link_fill_info(link, &info);
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seq_printf(seq,
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"netns_ino:\t%u\n"
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"attach_type:\t%u\n",
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info.netns.netns_ino,
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info.netns.attach_type);
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}
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static const struct bpf_link_ops bpf_netns_link_ops = {
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.release = bpf_netns_link_release,
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.dealloc = bpf_netns_link_dealloc,
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.update_prog = bpf_netns_link_update_prog,
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.fill_link_info = bpf_netns_link_fill_info,
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.show_fdinfo = bpf_netns_link_show_fdinfo,
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};
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int netns_bpf_prog_query(const union bpf_attr *attr,
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union bpf_attr __user *uattr)
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{
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__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
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u32 prog_id, prog_cnt = 0, flags = 0;
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enum netns_bpf_attach_type type;
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struct bpf_prog *attached;
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struct net *net;
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if (attr->query.query_flags)
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return -EINVAL;
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type = to_netns_bpf_attach_type(attr->query.attach_type);
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if (type < 0)
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return -EINVAL;
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net = get_net_ns_by_fd(attr->query.target_fd);
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if (IS_ERR(net))
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return PTR_ERR(net);
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rcu_read_lock();
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attached = rcu_dereference(net->bpf.progs[type]);
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if (attached) {
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prog_cnt = 1;
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prog_id = attached->aux->id;
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}
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rcu_read_unlock();
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put_net(net);
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if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
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return -EFAULT;
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if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt)))
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return -EFAULT;
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if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
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return 0;
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if (copy_to_user(prog_ids, &prog_id, sizeof(u32)))
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return -EFAULT;
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return 0;
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}
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int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
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{
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enum netns_bpf_attach_type type;
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struct net *net;
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int ret;
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type = to_netns_bpf_attach_type(attr->attach_type);
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if (type < 0)
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return -EINVAL;
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net = current->nsproxy->net_ns;
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mutex_lock(&netns_bpf_mutex);
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/* Attaching prog directly is not compatible with links */
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if (net->bpf.links[type]) {
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ret = -EEXIST;
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goto out_unlock;
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}
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switch (type) {
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case NETNS_BPF_FLOW_DISSECTOR:
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ret = flow_dissector_bpf_prog_attach(net, prog);
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break;
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default:
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ret = -EINVAL;
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break;
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}
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out_unlock:
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mutex_unlock(&netns_bpf_mutex);
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return ret;
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}
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/* Must be called with netns_bpf_mutex held. */
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static int __netns_bpf_prog_detach(struct net *net,
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enum netns_bpf_attach_type type)
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{
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struct bpf_prog *attached;
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/* Progs attached via links cannot be detached */
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if (net->bpf.links[type])
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return -EINVAL;
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attached = rcu_dereference_protected(net->bpf.progs[type],
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lockdep_is_held(&netns_bpf_mutex));
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if (!attached)
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return -ENOENT;
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RCU_INIT_POINTER(net->bpf.progs[type], NULL);
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bpf_prog_put(attached);
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return 0;
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}
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int netns_bpf_prog_detach(const union bpf_attr *attr)
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{
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enum netns_bpf_attach_type type;
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int ret;
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type = to_netns_bpf_attach_type(attr->attach_type);
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if (type < 0)
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return -EINVAL;
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mutex_lock(&netns_bpf_mutex);
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ret = __netns_bpf_prog_detach(current->nsproxy->net_ns, type);
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mutex_unlock(&netns_bpf_mutex);
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return ret;
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}
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static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
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enum netns_bpf_attach_type type)
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{
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struct bpf_prog *prog;
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int err;
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mutex_lock(&netns_bpf_mutex);
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/* Allow attaching only one prog or link for now */
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if (net->bpf.links[type]) {
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err = -E2BIG;
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goto out_unlock;
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}
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/* Links are not compatible with attaching prog directly */
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prog = rcu_dereference_protected(net->bpf.progs[type],
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lockdep_is_held(&netns_bpf_mutex));
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if (prog) {
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err = -EEXIST;
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goto out_unlock;
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}
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switch (type) {
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case NETNS_BPF_FLOW_DISSECTOR:
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err = flow_dissector_bpf_prog_attach(net, link->prog);
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break;
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default:
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err = -EINVAL;
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break;
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}
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if (err)
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goto out_unlock;
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net->bpf.links[type] = link;
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out_unlock:
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mutex_unlock(&netns_bpf_mutex);
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return err;
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}
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int netns_bpf_link_create(const union bpf_attr *attr, struct bpf_prog *prog)
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{
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enum netns_bpf_attach_type netns_type;
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struct bpf_link_primer link_primer;
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struct bpf_netns_link *net_link;
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enum bpf_attach_type type;
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struct net *net;
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int err;
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if (attr->link_create.flags)
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return -EINVAL;
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type = attr->link_create.attach_type;
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netns_type = to_netns_bpf_attach_type(type);
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if (netns_type < 0)
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return -EINVAL;
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net = get_net_ns_by_fd(attr->link_create.target_fd);
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if (IS_ERR(net))
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return PTR_ERR(net);
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net_link = kzalloc(sizeof(*net_link), GFP_USER);
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if (!net_link) {
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err = -ENOMEM;
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goto out_put_net;
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}
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bpf_link_init(&net_link->link, BPF_LINK_TYPE_NETNS,
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&bpf_netns_link_ops, prog);
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net_link->net = net;
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net_link->type = type;
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net_link->netns_type = netns_type;
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err = bpf_link_prime(&net_link->link, &link_primer);
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if (err) {
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kfree(net_link);
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goto out_put_net;
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}
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err = netns_bpf_link_attach(net, &net_link->link, netns_type);
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if (err) {
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bpf_link_cleanup(&link_primer);
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goto out_put_net;
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}
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put_net(net);
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return bpf_link_settle(&link_primer);
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out_put_net:
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put_net(net);
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return err;
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}
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static void __net_exit netns_bpf_pernet_pre_exit(struct net *net)
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{
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enum netns_bpf_attach_type type;
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struct bpf_link *link;
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mutex_lock(&netns_bpf_mutex);
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for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++) {
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link = net->bpf.links[type];
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if (link)
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bpf_netns_link_auto_detach(link);
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else
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__netns_bpf_prog_detach(net, type);
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}
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mutex_unlock(&netns_bpf_mutex);
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}
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static struct pernet_operations netns_bpf_pernet_ops __net_initdata = {
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.pre_exit = netns_bpf_pernet_pre_exit,
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};
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static int __init netns_bpf_init(void)
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{
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return register_pernet_subsys(&netns_bpf_pernet_ops);
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}
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subsys_initcall(netns_bpf_init);
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