diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h index a7eba43fe4e4ca..4b6e36288ddd3b 100644 --- a/include/net/flow_dissector.h +++ b/include/net/flow_dissector.h @@ -372,7 +372,8 @@ flow_dissector_init_keys(struct flow_dissector_key_control *key_control, } #ifdef CONFIG_BPF_SYSCALL -int flow_dissector_bpf_prog_attach(struct net *net, struct bpf_prog *prog); +int flow_dissector_bpf_prog_attach_check(struct net *net, + struct bpf_prog *prog); #endif /* CONFIG_BPF_SYSCALL */ #endif diff --git a/include/net/netns/bpf.h b/include/net/netns/bpf.h index a8dce2a380c8e8..0ca6a1b8718533 100644 --- a/include/net/netns/bpf.h +++ b/include/net/netns/bpf.h @@ -9,10 +9,13 @@ #include struct bpf_prog; +struct bpf_prog_array; struct netns_bpf { - struct bpf_prog __rcu *progs[MAX_NETNS_BPF_ATTACH_TYPE]; - struct bpf_link *links[MAX_NETNS_BPF_ATTACH_TYPE]; + /* Array of programs to run compiled from progs or links */ + struct bpf_prog_array __rcu *run_array[MAX_NETNS_BPF_ATTACH_TYPE]; + struct bpf_prog *progs[MAX_NETNS_BPF_ATTACH_TYPE]; + struct list_head links[MAX_NETNS_BPF_ATTACH_TYPE]; }; #endif /* __NETNS_BPF_H__ */ diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c index 78cf061f817938..7a34a8caf95452 100644 --- a/kernel/bpf/net_namespace.c +++ b/kernel/bpf/net_namespace.c @@ -19,18 +19,21 @@ struct bpf_netns_link { * with netns_bpf_mutex held. */ struct net *net; + struct list_head node; /* node in list of links attached to net */ }; /* Protects updates to netns_bpf */ DEFINE_MUTEX(netns_bpf_mutex); /* Must be called with netns_bpf_mutex held. */ -static void __net_exit bpf_netns_link_auto_detach(struct bpf_link *link) +static void netns_bpf_run_array_detach(struct net *net, + enum netns_bpf_attach_type type) { - struct bpf_netns_link *net_link = - container_of(link, struct bpf_netns_link, link); + struct bpf_prog_array *run_array; - net_link->net = NULL; + run_array = rcu_replace_pointer(net->bpf.run_array[type], NULL, + lockdep_is_held(&netns_bpf_mutex)); + bpf_prog_array_free(run_array); } static void bpf_netns_link_release(struct bpf_link *link) @@ -54,8 +57,8 @@ static void bpf_netns_link_release(struct bpf_link *link) if (!net) goto out_unlock; - net->bpf.links[type] = NULL; - RCU_INIT_POINTER(net->bpf.progs[type], NULL); + netns_bpf_run_array_detach(net, type); + list_del(&net_link->node); out_unlock: mutex_unlock(&netns_bpf_mutex); @@ -76,6 +79,7 @@ static int bpf_netns_link_update_prog(struct bpf_link *link, struct bpf_netns_link *net_link = container_of(link, struct bpf_netns_link, link); enum netns_bpf_attach_type type = net_link->netns_type; + struct bpf_prog_array *run_array; struct net *net; int ret = 0; @@ -93,8 +97,11 @@ static int bpf_netns_link_update_prog(struct bpf_link *link, goto out_unlock; } + run_array = rcu_dereference_protected(net->bpf.run_array[type], + lockdep_is_held(&netns_bpf_mutex)); + WRITE_ONCE(run_array->items[0].prog, new_prog); + old_prog = xchg(&link->prog, new_prog); - rcu_assign_pointer(net->bpf.progs[type], new_prog); bpf_prog_put(old_prog); out_unlock: @@ -142,14 +149,38 @@ static const struct bpf_link_ops bpf_netns_link_ops = { .show_fdinfo = bpf_netns_link_show_fdinfo, }; +/* Must be called with netns_bpf_mutex held. */ +static int __netns_bpf_prog_query(const union bpf_attr *attr, + union bpf_attr __user *uattr, + struct net *net, + enum netns_bpf_attach_type type) +{ + __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids); + struct bpf_prog_array *run_array; + u32 prog_cnt = 0, flags = 0; + + run_array = rcu_dereference_protected(net->bpf.run_array[type], + lockdep_is_held(&netns_bpf_mutex)); + if (run_array) + prog_cnt = bpf_prog_array_length(run_array); + + if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) + return -EFAULT; + if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt))) + return -EFAULT; + if (!attr->query.prog_cnt || !prog_ids || !prog_cnt) + return 0; + + return bpf_prog_array_copy_to_user(run_array, prog_ids, + attr->query.prog_cnt); +} + int netns_bpf_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) { - __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids); - u32 prog_id, prog_cnt = 0, flags = 0; enum netns_bpf_attach_type type; - struct bpf_prog *attached; struct net *net; + int ret; if (attr->query.query_flags) return -EINVAL; @@ -162,33 +193,19 @@ int netns_bpf_prog_query(const union bpf_attr *attr, if (IS_ERR(net)) return PTR_ERR(net); - rcu_read_lock(); - attached = rcu_dereference(net->bpf.progs[type]); - if (attached) { - prog_cnt = 1; - prog_id = attached->aux->id; - } - rcu_read_unlock(); + mutex_lock(&netns_bpf_mutex); + ret = __netns_bpf_prog_query(attr, uattr, net, type); + mutex_unlock(&netns_bpf_mutex); put_net(net); - - if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) - return -EFAULT; - if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt))) - return -EFAULT; - - if (!attr->query.prog_cnt || !prog_ids || !prog_cnt) - return 0; - - if (copy_to_user(prog_ids, &prog_id, sizeof(u32))) - return -EFAULT; - - return 0; + return ret; } int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog) { + struct bpf_prog_array *run_array; enum netns_bpf_attach_type type; + struct bpf_prog *attached; struct net *net; int ret; @@ -200,19 +217,47 @@ int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog) mutex_lock(&netns_bpf_mutex); /* Attaching prog directly is not compatible with links */ - if (net->bpf.links[type]) { + if (!list_empty(&net->bpf.links[type])) { ret = -EEXIST; goto out_unlock; } switch (type) { case NETNS_BPF_FLOW_DISSECTOR: - ret = flow_dissector_bpf_prog_attach(net, prog); + ret = flow_dissector_bpf_prog_attach_check(net, prog); break; default: ret = -EINVAL; break; } + if (ret) + goto out_unlock; + + attached = net->bpf.progs[type]; + if (attached == prog) { + /* The same program cannot be attached twice */ + ret = -EINVAL; + goto out_unlock; + } + + run_array = rcu_dereference_protected(net->bpf.run_array[type], + lockdep_is_held(&netns_bpf_mutex)); + if (run_array) { + WRITE_ONCE(run_array->items[0].prog, prog); + } else { + run_array = bpf_prog_array_alloc(1, GFP_KERNEL); + if (!run_array) { + ret = -ENOMEM; + goto out_unlock; + } + run_array->items[0].prog = prog; + rcu_assign_pointer(net->bpf.run_array[type], run_array); + } + + net->bpf.progs[type] = prog; + if (attached) + bpf_prog_put(attached); + out_unlock: mutex_unlock(&netns_bpf_mutex); @@ -226,14 +271,14 @@ static int __netns_bpf_prog_detach(struct net *net, struct bpf_prog *attached; /* Progs attached via links cannot be detached */ - if (net->bpf.links[type]) + if (!list_empty(&net->bpf.links[type])) return -EINVAL; - attached = rcu_dereference_protected(net->bpf.progs[type], - lockdep_is_held(&netns_bpf_mutex)); + attached = net->bpf.progs[type]; if (!attached) return -ENOENT; - RCU_INIT_POINTER(net->bpf.progs[type], NULL); + netns_bpf_run_array_detach(net, type); + net->bpf.progs[type] = NULL; bpf_prog_put(attached); return 0; } @@ -257,27 +302,27 @@ int netns_bpf_prog_detach(const union bpf_attr *attr) static int netns_bpf_link_attach(struct net *net, struct bpf_link *link, enum netns_bpf_attach_type type) { - struct bpf_prog *prog; + struct bpf_netns_link *net_link = + container_of(link, struct bpf_netns_link, link); + struct bpf_prog_array *run_array; int err; mutex_lock(&netns_bpf_mutex); /* Allow attaching only one prog or link for now */ - if (net->bpf.links[type]) { + if (!list_empty(&net->bpf.links[type])) { err = -E2BIG; goto out_unlock; } /* Links are not compatible with attaching prog directly */ - prog = rcu_dereference_protected(net->bpf.progs[type], - lockdep_is_held(&netns_bpf_mutex)); - if (prog) { + if (net->bpf.progs[type]) { err = -EEXIST; goto out_unlock; } switch (type) { case NETNS_BPF_FLOW_DISSECTOR: - err = flow_dissector_bpf_prog_attach(net, link->prog); + err = flow_dissector_bpf_prog_attach_check(net, link->prog); break; default: err = -EINVAL; @@ -286,7 +331,15 @@ static int netns_bpf_link_attach(struct net *net, struct bpf_link *link, if (err) goto out_unlock; - net->bpf.links[type] = link; + run_array = bpf_prog_array_alloc(1, GFP_KERNEL); + if (!run_array) { + err = -ENOMEM; + goto out_unlock; + } + run_array->items[0].prog = link->prog; + rcu_assign_pointer(net->bpf.run_array[type], run_array); + + list_add_tail(&net_link->node, &net->bpf.links[type]); out_unlock: mutex_unlock(&netns_bpf_mutex); @@ -345,23 +398,34 @@ int netns_bpf_link_create(const union bpf_attr *attr, struct bpf_prog *prog) 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_link *link; + struct bpf_netns_link *net_link; mutex_lock(&netns_bpf_mutex); for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++) { - link = net->bpf.links[type]; - if (link) - bpf_netns_link_auto_detach(link); - else - __netns_bpf_prog_detach(net, type); + netns_bpf_run_array_detach(net, type); + list_for_each_entry(net_link, &net->bpf.links[type], node) + net_link->net = NULL; /* auto-detach link */ + 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, }; diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index d02df0b6d0d99a..142a8824f0a8ef 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -70,10 +70,10 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector, EXPORT_SYMBOL(skb_flow_dissector_init); #ifdef CONFIG_BPF_SYSCALL -int flow_dissector_bpf_prog_attach(struct net *net, struct bpf_prog *prog) +int flow_dissector_bpf_prog_attach_check(struct net *net, + struct bpf_prog *prog) { enum netns_bpf_attach_type type = NETNS_BPF_FLOW_DISSECTOR; - struct bpf_prog *attached; if (net == &init_net) { /* BPF flow dissector in the root namespace overrides @@ -86,26 +86,17 @@ int flow_dissector_bpf_prog_attach(struct net *net, struct bpf_prog *prog) for_each_net(ns) { if (ns == &init_net) continue; - if (rcu_access_pointer(ns->bpf.progs[type])) + if (rcu_access_pointer(ns->bpf.run_array[type])) return -EEXIST; } } else { /* Make sure root flow dissector is not attached * when attaching to the non-root namespace. */ - if (rcu_access_pointer(init_net.bpf.progs[type])) + if (rcu_access_pointer(init_net.bpf.run_array[type])) return -EEXIST; } - attached = rcu_dereference_protected(net->bpf.progs[type], - lockdep_is_held(&netns_bpf_mutex)); - if (attached == prog) - /* The same program cannot be attached twice */ - return -EINVAL; - - rcu_assign_pointer(net->bpf.progs[type], prog); - if (attached) - bpf_prog_put(attached); return 0; } #endif /* CONFIG_BPF_SYSCALL */ @@ -903,7 +894,6 @@ bool __skb_flow_dissect(const struct net *net, struct flow_dissector_key_addrs *key_addrs; struct flow_dissector_key_tags *key_tags; struct flow_dissector_key_vlan *key_vlan; - struct bpf_prog *attached = NULL; enum flow_dissect_ret fdret; enum flow_dissector_key_id dissector_vlan = FLOW_DISSECTOR_KEY_MAX; bool mpls_el = false; @@ -960,14 +950,14 @@ bool __skb_flow_dissect(const struct net *net, WARN_ON_ONCE(!net); if (net) { enum netns_bpf_attach_type type = NETNS_BPF_FLOW_DISSECTOR; + struct bpf_prog_array *run_array; rcu_read_lock(); - attached = rcu_dereference(init_net.bpf.progs[type]); - - if (!attached) - attached = rcu_dereference(net->bpf.progs[type]); + run_array = rcu_dereference(init_net.bpf.run_array[type]); + if (!run_array) + run_array = rcu_dereference(net->bpf.run_array[type]); - if (attached) { + if (run_array) { struct bpf_flow_keys flow_keys; struct bpf_flow_dissector ctx = { .flow_keys = &flow_keys, @@ -975,6 +965,7 @@ bool __skb_flow_dissect(const struct net *net, .data_end = data + hlen, }; __be16 n_proto = proto; + struct bpf_prog *prog; if (skb) { ctx.skb = skb; @@ -985,7 +976,8 @@ bool __skb_flow_dissect(const struct net *net, n_proto = skb->protocol; } - ret = bpf_flow_dissect(attached, &ctx, n_proto, nhoff, + prog = READ_ONCE(run_array->items[0].prog); + ret = bpf_flow_dissect(prog, &ctx, n_proto, nhoff, hlen, flags); __skb_flow_bpf_to_target(&flow_keys, flow_dissector, target_container); diff --git a/tools/testing/selftests/bpf/prog_tests/flow_dissector_reattach.c b/tools/testing/selftests/bpf/prog_tests/flow_dissector_reattach.c index 15cb554a66d8c8..a2db3b0f84db09 100644 --- a/tools/testing/selftests/bpf/prog_tests/flow_dissector_reattach.c +++ b/tools/testing/selftests/bpf/prog_tests/flow_dissector_reattach.c @@ -1,9 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 /* - * Test that the flow_dissector program can be updated with a single - * syscall by attaching a new program that replaces the existing one. - * - * Corner case - the same program cannot be attached twice. + * Tests for attaching, detaching, and replacing flow_dissector BPF program. */ #define _GNU_SOURCE @@ -308,6 +305,31 @@ static void test_link_update_replace_old_prog(int netns, int prog1, int prog2) CHECK_FAIL(prog_is_attached(netns)); } +static void test_link_update_same_prog(int netns, int prog1, int prog2) +{ + DECLARE_LIBBPF_OPTS(bpf_link_create_opts, create_opts); + DECLARE_LIBBPF_OPTS(bpf_link_update_opts, update_opts); + int err, link; + + link = bpf_link_create(prog1, netns, BPF_FLOW_DISSECTOR, &create_opts); + if (CHECK_FAIL(link < 0)) { + perror("bpf_link_create(prog1)"); + return; + } + CHECK_FAIL(query_attached_prog_id(netns) != query_prog_id(prog1)); + + /* Expect success updating the prog with the same one */ + update_opts.flags = 0; + update_opts.old_prog_fd = 0; + err = bpf_link_update(link, prog1, &update_opts); + if (CHECK_FAIL(err)) + perror("bpf_link_update"); + CHECK_FAIL(query_attached_prog_id(netns) != query_prog_id(prog1)); + + close(link); + CHECK_FAIL(prog_is_attached(netns)); +} + static void test_link_update_invalid_opts(int netns, int prog1, int prog2) { DECLARE_LIBBPF_OPTS(bpf_link_create_opts, create_opts); @@ -571,6 +593,8 @@ static void run_tests(int netns) test_link_update_no_old_prog }, { "link update with replace old prog", test_link_update_replace_old_prog }, + { "link update with same prog", + test_link_update_same_prog }, { "link update invalid opts", test_link_update_invalid_opts }, { "link update invalid prog",