Merge branch 'bpf-multi-prog-prep'
Jakub Sitnicki says: ==================== This patch set prepares ground for link-based multi-prog attachment for future netns attach types, with BPF_SK_LOOKUP attach type in mind [0]. Two changes are needed in order to attach and run a series of BPF programs: 1) an bpf_prog_array of programs to run (patch #2), and 2) a list of attached links to keep track of attachments (patch #3). Nothing changes for BPF flow_dissector. Just as before only one program can be attached to netns. In v3 I've simplified patch #2 that introduces bpf_prog_array to take advantage of the fact that it will hold at most one program for now. In particular, I'm no longer using bpf_prog_array_copy. It turned out to be less suitable for link operations than I thought as it fails to append the same BPF program. bpf_prog_array_replace_item is also gone, because we know we always want to replace the first element in prog_array. Naturally the code that handles bpf_prog_array will need change once more when there is a program type that allows multi-prog attachment. But I feel it will be better to do it gradually and present it together with tests that actually exercise multi-prog code paths. [0] https://lore.kernel.org/bpf/20200511185218.1422406-1-jakub@cloudflare.com/ v2 -> v3: - Don't check if run_array is null in link update callback. (Martin) - Allow updating the link with the same BPF program. (Andrii) - Add patch #4 with a test for the above case. - Kill bpf_prog_array_replace_item. Access the run_array directly. - Switch from bpf_prog_array_copy() to bpf_prog_array_alloc(1, ...). - Replace rcu_deref_protected & RCU_INIT_POINTER with rcu_replace_pointer. - Drop Andrii's Ack from patch #2. Code changed. v1 -> v2: - Show with a (void) cast that bpf_prog_array_replace_item() return value is ignored on purpose. (Andrii) - Explain why bpf-cgroup cannot replace programs in bpf_prog_array based on bpf_prog pointer comparison in patch #2 description. (Andrii) ==================== Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov
Коммит
951f38cf08
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@ -372,7 +372,8 @@ flow_dissector_init_keys(struct flow_dissector_key_control *key_control,
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}
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#ifdef CONFIG_BPF_SYSCALL
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int flow_dissector_bpf_prog_attach(struct net *net, struct bpf_prog *prog);
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int flow_dissector_bpf_prog_attach_check(struct net *net,
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struct bpf_prog *prog);
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#endif /* CONFIG_BPF_SYSCALL */
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#endif
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@ -9,10 +9,13 @@
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#include <linux/bpf-netns.h>
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struct bpf_prog;
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struct bpf_prog_array;
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struct netns_bpf {
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struct bpf_prog __rcu *progs[MAX_NETNS_BPF_ATTACH_TYPE];
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struct bpf_link *links[MAX_NETNS_BPF_ATTACH_TYPE];
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/* Array of programs to run compiled from progs or links */
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struct bpf_prog_array __rcu *run_array[MAX_NETNS_BPF_ATTACH_TYPE];
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struct bpf_prog *progs[MAX_NETNS_BPF_ATTACH_TYPE];
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struct list_head links[MAX_NETNS_BPF_ATTACH_TYPE];
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};
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#endif /* __NETNS_BPF_H__ */
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@ -19,18 +19,21 @@ struct bpf_netns_link {
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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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/* 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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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_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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net_link->net = NULL;
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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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static void bpf_netns_link_release(struct bpf_link *link)
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@ -54,8 +57,8 @@ static void bpf_netns_link_release(struct bpf_link *link)
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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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netns_bpf_run_array_detach(net, type);
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list_del(&net_link->node);
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out_unlock:
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mutex_unlock(&netns_bpf_mutex);
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@ -76,6 +79,7 @@ static int bpf_netns_link_update_prog(struct bpf_link *link,
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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 ret = 0;
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@ -93,8 +97,11 @@ static int bpf_netns_link_update_prog(struct bpf_link *link,
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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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WRITE_ONCE(run_array->items[0].prog, new_prog);
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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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@ -142,14 +149,38 @@ static const struct bpf_link_ops bpf_netns_link_ops = {
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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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__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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int ret;
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if (attr->query.query_flags)
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return -EINVAL;
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@ -162,33 +193,19 @@ int netns_bpf_prog_query(const union bpf_attr *attr,
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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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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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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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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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@ -200,19 +217,47 @@ int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
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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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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(net, prog);
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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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out_unlock:
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mutex_unlock(&netns_bpf_mutex);
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@ -226,14 +271,14 @@ static int __netns_bpf_prog_detach(struct net *net,
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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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if (!list_empty(&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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attached = net->bpf.progs[type];
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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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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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@ -257,27 +302,27 @@ int netns_bpf_prog_detach(const union bpf_attr *attr)
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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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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 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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if (!list_empty(&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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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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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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err = flow_dissector_bpf_prog_attach_check(net, link->prog);
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break;
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default:
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err = -EINVAL;
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@ -286,7 +331,15 @@ static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
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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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run_array = bpf_prog_array_alloc(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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run_array->items[0].prog = link->prog;
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rcu_assign_pointer(net->bpf.run_array[type], run_array);
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list_add_tail(&net_link->node, &net->bpf.links[type]);
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out_unlock:
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mutex_unlock(&netns_bpf_mutex);
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@ -345,23 +398,34 @@ out_put_net:
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return err;
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}
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static int __net_init netns_bpf_pernet_init(struct net *net)
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{
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int type;
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|
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for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++)
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INIT_LIST_HEAD(&net->bpf.links[type]);
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|
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return 0;
|
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}
|
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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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struct bpf_netns_link *net_link;
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|
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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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netns_bpf_run_array_detach(net, type);
|
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list_for_each_entry(net_link, &net->bpf.links[type], node)
|
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net_link->net = NULL; /* auto-detach link */
|
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if (net->bpf.progs[type])
|
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bpf_prog_put(net->bpf.progs[type]);
|
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}
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mutex_unlock(&netns_bpf_mutex);
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}
|
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|
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static struct pernet_operations netns_bpf_pernet_ops __net_initdata = {
|
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.init = netns_bpf_pernet_init,
|
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.pre_exit = netns_bpf_pernet_pre_exit,
|
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};
|
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|
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|
|
|
|||
|
|
@ -70,10 +70,10 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
|
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EXPORT_SYMBOL(skb_flow_dissector_init);
|
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|
||||
#ifdef CONFIG_BPF_SYSCALL
|
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int flow_dissector_bpf_prog_attach(struct net *net, struct bpf_prog *prog)
|
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int flow_dissector_bpf_prog_attach_check(struct net *net,
|
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struct bpf_prog *prog)
|
||||
{
|
||||
enum netns_bpf_attach_type type = NETNS_BPF_FLOW_DISSECTOR;
|
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struct bpf_prog *attached;
|
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|
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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)
|
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for_each_net(ns) {
|
||||
if (ns == &init_net)
|
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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]);
|
||||
run_array = rcu_dereference(init_net.bpf.run_array[type]);
|
||||
if (!run_array)
|
||||
run_array = rcu_dereference(net->bpf.run_array[type]);
|
||||
|
||||
if (!attached)
|
||||
attached = rcu_dereference(net->bpf.progs[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);
|
||||
|
|
|
|||
|
|
@ -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",
|
||||
|
|
|
|||
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Ссылка в новой задаче