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566 lines
13 KiB
566 lines
13 KiB
// 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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/* |
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* Functions to manage BPF programs attached to netns |
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*/ |
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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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|
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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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struct list_head node; /* node in list of links attached to net */ |
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}; |
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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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|
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static void netns_bpf_attach_type_unneed(enum netns_bpf_attach_type type) |
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{ |
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switch (type) { |
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#ifdef CONFIG_INET |
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case NETNS_BPF_SK_LOOKUP: |
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static_branch_dec(&bpf_sk_lookup_enabled); |
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break; |
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#endif |
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default: |
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break; |
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} |
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} |
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|
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static void netns_bpf_attach_type_need(enum netns_bpf_attach_type type) |
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{ |
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switch (type) { |
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#ifdef CONFIG_INET |
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case NETNS_BPF_SK_LOOKUP: |
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static_branch_inc(&bpf_sk_lookup_enabled); |
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break; |
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#endif |
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default: |
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break; |
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} |
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} |
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/* Must be called with netns_bpf_mutex held. */ |
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static void netns_bpf_run_array_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_array *run_array; |
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|
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run_array = rcu_replace_pointer(net->bpf.run_array[type], NULL, |
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lockdep_is_held(&netns_bpf_mutex)); |
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bpf_prog_array_free(run_array); |
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} |
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|
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static int link_index(struct net *net, enum netns_bpf_attach_type type, |
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struct bpf_netns_link *link) |
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{ |
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struct bpf_netns_link *pos; |
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int i = 0; |
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|
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list_for_each_entry(pos, &net->bpf.links[type], node) { |
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if (pos == link) |
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return i; |
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i++; |
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} |
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return -ENOENT; |
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} |
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|
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static int link_count(struct net *net, enum netns_bpf_attach_type type) |
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{ |
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struct list_head *pos; |
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int i = 0; |
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|
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list_for_each(pos, &net->bpf.links[type]) |
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i++; |
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return i; |
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} |
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|
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static void fill_prog_array(struct net *net, enum netns_bpf_attach_type type, |
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struct bpf_prog_array *prog_array) |
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{ |
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struct bpf_netns_link *pos; |
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unsigned int i = 0; |
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|
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list_for_each_entry(pos, &net->bpf.links[type], node) { |
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prog_array->items[i].prog = pos->link.prog; |
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i++; |
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} |
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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 bpf_prog_array *old_array, *new_array; |
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struct net *net; |
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int cnt, idx; |
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|
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mutex_lock(&netns_bpf_mutex); |
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|
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/* We can race with cleanup_net, but if we see a non-NULL |
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* struct net pointer, pre_exit has not run yet and wait for |
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* 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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|
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/* Mark attach point as unused */ |
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netns_bpf_attach_type_unneed(type); |
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|
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/* Remember link position in case of safe delete */ |
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idx = link_index(net, type, net_link); |
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list_del(&net_link->node); |
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|
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cnt = link_count(net, type); |
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if (!cnt) { |
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netns_bpf_run_array_detach(net, type); |
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goto out_unlock; |
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} |
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|
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old_array = rcu_dereference_protected(net->bpf.run_array[type], |
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lockdep_is_held(&netns_bpf_mutex)); |
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new_array = bpf_prog_array_alloc(cnt, GFP_KERNEL); |
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if (!new_array) { |
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WARN_ON(bpf_prog_array_delete_safe_at(old_array, idx)); |
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goto out_unlock; |
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} |
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fill_prog_array(net, type, new_array); |
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rcu_assign_pointer(net->bpf.run_array[type], new_array); |
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bpf_prog_array_free(old_array); |
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out_unlock: |
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net_link->net = NULL; |
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mutex_unlock(&netns_bpf_mutex); |
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} |
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static int bpf_netns_link_detach(struct bpf_link *link) |
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{ |
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bpf_netns_link_release(link); |
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return 0; |
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} |
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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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|
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kfree(net_link); |
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} |
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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 bpf_prog_array *run_array; |
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struct net *net; |
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int idx, ret; |
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|
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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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|
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mutex_lock(&netns_bpf_mutex); |
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|
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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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run_array = rcu_dereference_protected(net->bpf.run_array[type], |
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lockdep_is_held(&netns_bpf_mutex)); |
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idx = link_index(net, type, net_link); |
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ret = bpf_prog_array_update_at(run_array, idx, new_prog); |
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if (ret) |
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goto out_unlock; |
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old_prog = xchg(&link->prog, 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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|
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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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.detach = bpf_netns_link_detach, |
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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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/* Must be called with netns_bpf_mutex held. */ |
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static int __netns_bpf_prog_query(const union bpf_attr *attr, |
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union bpf_attr __user *uattr, |
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struct net *net, |
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enum netns_bpf_attach_type type) |
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{ |
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__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids); |
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struct bpf_prog_array *run_array; |
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u32 prog_cnt = 0, flags = 0; |
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run_array = rcu_dereference_protected(net->bpf.run_array[type], |
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lockdep_is_held(&netns_bpf_mutex)); |
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if (run_array) |
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prog_cnt = bpf_prog_array_length(run_array); |
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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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return bpf_prog_array_copy_to_user(run_array, prog_ids, |
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attr->query.prog_cnt); |
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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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enum netns_bpf_attach_type type; |
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struct net *net; |
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int ret; |
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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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mutex_lock(&netns_bpf_mutex); |
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ret = __netns_bpf_prog_query(attr, uattr, net, type); |
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mutex_unlock(&netns_bpf_mutex); |
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put_net(net); |
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return ret; |
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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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struct bpf_prog_array *run_array; |
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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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int ret; |
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if (attr->target_fd || attr->attach_flags || attr->replace_bpf_fd) |
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return -EINVAL; |
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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 (!list_empty(&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_check(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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if (ret) |
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goto out_unlock; |
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attached = net->bpf.progs[type]; |
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if (attached == prog) { |
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/* The same program cannot be attached twice */ |
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ret = -EINVAL; |
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goto out_unlock; |
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} |
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run_array = rcu_dereference_protected(net->bpf.run_array[type], |
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lockdep_is_held(&netns_bpf_mutex)); |
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if (run_array) { |
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WRITE_ONCE(run_array->items[0].prog, prog); |
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} else { |
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run_array = bpf_prog_array_alloc(1, GFP_KERNEL); |
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if (!run_array) { |
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ret = -ENOMEM; |
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goto out_unlock; |
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} |
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run_array->items[0].prog = prog; |
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rcu_assign_pointer(net->bpf.run_array[type], run_array); |
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} |
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net->bpf.progs[type] = prog; |
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if (attached) |
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bpf_prog_put(attached); |
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|
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out_unlock: |
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mutex_unlock(&netns_bpf_mutex); |
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|
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return ret; |
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} |
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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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struct bpf_prog *old) |
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{ |
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struct bpf_prog *attached; |
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|
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/* Progs attached via links cannot be detached */ |
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if (!list_empty(&net->bpf.links[type])) |
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return -EINVAL; |
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attached = net->bpf.progs[type]; |
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if (!attached || attached != old) |
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return -ENOENT; |
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netns_bpf_run_array_detach(net, type); |
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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, enum bpf_prog_type ptype) |
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{ |
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enum netns_bpf_attach_type type; |
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struct bpf_prog *prog; |
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int ret; |
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|
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if (attr->target_fd) |
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return -EINVAL; |
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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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|
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prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype); |
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if (IS_ERR(prog)) |
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return PTR_ERR(prog); |
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mutex_lock(&netns_bpf_mutex); |
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ret = __netns_bpf_prog_detach(current->nsproxy->net_ns, type, prog); |
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mutex_unlock(&netns_bpf_mutex); |
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bpf_prog_put(prog); |
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return ret; |
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} |
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|
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static int netns_bpf_max_progs(enum netns_bpf_attach_type type) |
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{ |
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switch (type) { |
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case NETNS_BPF_FLOW_DISSECTOR: |
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return 1; |
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case NETNS_BPF_SK_LOOKUP: |
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return 64; |
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default: |
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return 0; |
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} |
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} |
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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_netns_link *net_link = |
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container_of(link, struct bpf_netns_link, link); |
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struct bpf_prog_array *run_array; |
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int cnt, err; |
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|
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mutex_lock(&netns_bpf_mutex); |
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|
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cnt = link_count(net, type); |
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if (cnt >= netns_bpf_max_progs(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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if (net->bpf.progs[type]) { |
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err = -EEXIST; |
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goto out_unlock; |
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} |
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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_check(net, link->prog); |
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break; |
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case NETNS_BPF_SK_LOOKUP: |
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err = 0; /* nothing to check */ |
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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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run_array = bpf_prog_array_alloc(cnt + 1, GFP_KERNEL); |
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if (!run_array) { |
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err = -ENOMEM; |
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goto out_unlock; |
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} |
|
|
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list_add_tail(&net_link->node, &net->bpf.links[type]); |
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|
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fill_prog_array(net, type, run_array); |
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run_array = rcu_replace_pointer(net->bpf.run_array[type], run_array, |
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lockdep_is_held(&netns_bpf_mutex)); |
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bpf_prog_array_free(run_array); |
|
|
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/* Mark attach point as used */ |
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netns_bpf_attach_type_need(type); |
|
|
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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); |
|
if (!net_link) { |
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err = -ENOMEM; |
|
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); |
|
net_link->net = net; |
|
net_link->type = type; |
|
net_link->netns_type = netns_type; |
|
|
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err = bpf_link_prime(&net_link->link, &link_primer); |
|
if (err) { |
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kfree(net_link); |
|
goto out_put_net; |
|
} |
|
|
|
err = netns_bpf_link_attach(net, &net_link->link, netns_type); |
|
if (err) { |
|
bpf_link_cleanup(&link_primer); |
|
goto out_put_net; |
|
} |
|
|
|
put_net(net); |
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return bpf_link_settle(&link_primer); |
|
|
|
out_put_net: |
|
put_net(net); |
|
return err; |
|
} |
|
|
|
static int __net_init netns_bpf_pernet_init(struct net *net) |
|
{ |
|
int type; |
|
|
|
for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++) |
|
INIT_LIST_HEAD(&net->bpf.links[type]); |
|
|
|
return 0; |
|
} |
|
|
|
static void __net_exit netns_bpf_pernet_pre_exit(struct net *net) |
|
{ |
|
enum netns_bpf_attach_type type; |
|
struct bpf_netns_link *net_link; |
|
|
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mutex_lock(&netns_bpf_mutex); |
|
for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++) { |
|
netns_bpf_run_array_detach(net, type); |
|
list_for_each_entry(net_link, &net->bpf.links[type], node) { |
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net_link->net = NULL; /* auto-detach link */ |
|
netns_bpf_attach_type_unneed(type); |
|
} |
|
if (net->bpf.progs[type]) |
|
bpf_prog_put(net->bpf.progs[type]); |
|
} |
|
mutex_unlock(&netns_bpf_mutex); |
|
} |
|
|
|
static struct pernet_operations netns_bpf_pernet_ops __net_initdata = { |
|
.init = netns_bpf_pernet_init, |
|
.pre_exit = netns_bpf_pernet_pre_exit, |
|
}; |
|
|
|
static int __init netns_bpf_init(void) |
|
{ |
|
return register_pernet_subsys(&netns_bpf_pernet_ops); |
|
} |
|
|
|
subsys_initcall(netns_bpf_init);
|
|
|