The fact that we don't know which device the program is going to be used on is quite limiting in current eBPF infrastructure. We have to reverse or limit the changes which kernel makes to the loaded bytecode if we want it to be offloaded to a networking device. We also have to invent new APIs for debugging and troubleshooting support. Make it possible to load programs for a specific netdev. This helps us to bring the debug information closer to the core eBPF infrastructure (e.g. we will be able to reuse the verifer log in device JIT). It allows device JITs to perform translation on the original bytecode. __bpf_prog_get() when called to get a reference for an attachment point will now refuse to give it if program has a device assigned. Following patches will add a version of that function which passes the expected netdev in. @type argument in __bpf_prog_get() is renamed to attach_type to make it clearer that it's only set on attachment. All calls to ndo_bpf are protected by rtnl, only verifier callbacks are not. We need a wait queue to make sure netdev doesn't get destroyed while verifier is still running and calling its driver. Change-Id: Iba7b96574abc005ad3351d6db2528eb534e47561 Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Simon Horman <simon.horman@netronome.com> Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Jakub Kicinski
7 years ago
committed by
Ruchit
parent
b338ae9bc4
commit
c3a78a941a
@ -0,0 +1,182 @@ |
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#include <linux/bpf.h> |
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#include <linux/bpf_verifier.h> |
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#include <linux/bug.h> |
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#include <linux/list.h> |
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#include <linux/netdevice.h> |
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#include <linux/printk.h> |
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#include <linux/rtnetlink.h> |
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/* protected by RTNL */ |
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static LIST_HEAD(bpf_prog_offload_devs); |
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int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr) |
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{ |
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struct net *net = current->nsproxy->net_ns; |
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struct bpf_dev_offload *offload; |
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if (!capable(CAP_SYS_ADMIN)) |
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return -EPERM; |
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if (attr->prog_flags) |
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return -EINVAL; |
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offload = kzalloc(sizeof(*offload), GFP_USER); |
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if (!offload) |
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return -ENOMEM; |
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offload->prog = prog; |
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init_waitqueue_head(&offload->verifier_done); |
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rtnl_lock(); |
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offload->netdev = __dev_get_by_index(net, attr->prog_target_ifindex); |
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if (!offload->netdev) { |
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rtnl_unlock(); |
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kfree(offload); |
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return -EINVAL; |
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} |
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prog->aux->offload = offload; |
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list_add_tail(&offload->offloads, &bpf_prog_offload_devs); |
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rtnl_unlock(); |
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return 0; |
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} |
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static int __bpf_offload_ndo(struct bpf_prog *prog, enum bpf_netdev_command cmd, |
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struct netdev_bpf *data) |
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{ |
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struct net_device *netdev = prog->aux->offload->netdev; |
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ASSERT_RTNL(); |
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if (!netdev) |
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return -ENODEV; |
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if (!netdev->netdev_ops->ndo_bpf) |
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return -EOPNOTSUPP; |
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data->command = cmd; |
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return netdev->netdev_ops->ndo_bpf(netdev, data); |
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} |
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int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env) |
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{ |
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struct netdev_bpf data = {}; |
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int err; |
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data.verifier.prog = env->prog; |
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rtnl_lock(); |
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err = __bpf_offload_ndo(env->prog, BPF_OFFLOAD_VERIFIER_PREP, &data); |
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if (err) |
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goto exit_unlock; |
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env->dev_ops = data.verifier.ops; |
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env->prog->aux->offload->dev_state = true; |
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env->prog->aux->offload->verifier_running = true; |
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exit_unlock: |
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rtnl_unlock(); |
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return err; |
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} |
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static void __bpf_prog_offload_destroy(struct bpf_prog *prog) |
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{ |
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struct bpf_dev_offload *offload = prog->aux->offload; |
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struct netdev_bpf data = {}; |
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data.offload.prog = prog; |
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if (offload->verifier_running) |
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wait_event(offload->verifier_done, !offload->verifier_running); |
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if (offload->dev_state) |
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WARN_ON(__bpf_offload_ndo(prog, BPF_OFFLOAD_DESTROY, &data)); |
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offload->dev_state = false; |
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list_del_init(&offload->offloads); |
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offload->netdev = NULL; |
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} |
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void bpf_prog_offload_destroy(struct bpf_prog *prog) |
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{ |
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struct bpf_dev_offload *offload = prog->aux->offload; |
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offload->verifier_running = false; |
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wake_up(&offload->verifier_done); |
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rtnl_lock(); |
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__bpf_prog_offload_destroy(prog); |
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rtnl_unlock(); |
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kfree(offload); |
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} |
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static int bpf_prog_offload_translate(struct bpf_prog *prog) |
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{ |
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struct bpf_dev_offload *offload = prog->aux->offload; |
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struct netdev_bpf data = {}; |
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int ret; |
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data.offload.prog = prog; |
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offload->verifier_running = false; |
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wake_up(&offload->verifier_done); |
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rtnl_lock(); |
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ret = __bpf_offload_ndo(prog, BPF_OFFLOAD_TRANSLATE, &data); |
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rtnl_unlock(); |
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return ret; |
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} |
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static unsigned int bpf_prog_warn_on_exec(const void *ctx, |
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const struct bpf_insn *insn) |
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{ |
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WARN(1, "attempt to execute device eBPF program on the host!"); |
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return 0; |
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} |
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int bpf_prog_offload_compile(struct bpf_prog *prog) |
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{ |
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prog->bpf_func = bpf_prog_warn_on_exec; |
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return bpf_prog_offload_translate(prog); |
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} |
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const struct bpf_verifier_ops bpf_offload_prog_ops = { |
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}; |
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static int bpf_offload_notification(struct notifier_block *notifier, |
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ulong event, void *ptr) |
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{ |
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struct net_device *netdev = netdev_notifier_info_to_dev(ptr); |
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struct bpf_dev_offload *offload, *tmp; |
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ASSERT_RTNL(); |
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switch (event) { |
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case NETDEV_UNREGISTER: |
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list_for_each_entry_safe(offload, tmp, &bpf_prog_offload_devs, |
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offloads) { |
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if (offload->netdev == netdev) |
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__bpf_prog_offload_destroy(offload->prog); |
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} |
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break; |
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default: |
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break; |
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} |
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return NOTIFY_OK; |
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} |
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static struct notifier_block bpf_offload_notifier = { |
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.notifier_call = bpf_offload_notification, |
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}; |
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static int __init bpf_offload_init(void) |
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{ |
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register_netdevice_notifier(&bpf_offload_notifier); |
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return 0; |
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} |
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subsys_initcall(bpf_offload_init); |
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