kernel/bpf/offload.c

   1 #include <linux/bpf.h>
   2 #include <linux/bpf_verifier.h>
   3 #include <linux/bug.h>
   4 #include <linux/list.h>
   5 #include <linux/netdevice.h>
   6 #include <linux/printk.h>
   7 #include <linux/rtnetlink.h>
   8
   9 /* protected by RTNL */
  10 static LIST_HEAD(bpf_prog_offload_devs);
  11
  12 int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr)
  13 {
  14         struct net *net = current->nsproxy->net_ns;
  15         struct bpf_dev_offload *offload;
  16
  17         if (attr->prog_type != BPF_PROG_TYPE_SCHED_CLS &&
  18             attr->prog_type != BPF_PROG_TYPE_XDP)
  19                 return -EINVAL;
  20
  21         if (attr->prog_flags)
  22                 return -EINVAL;
  23
  24         offload = kzalloc(sizeof(*offload), GFP_USER);
  25         if (!offload)
  26                 return -ENOMEM;
  27
  28         offload->prog = prog;
  29         init_waitqueue_head(&offload->verifier_done);
  30
  31         rtnl_lock();
  32         offload->netdev = __dev_get_by_index(net, attr->prog_ifindex);
  33         if (!offload->netdev) {
  34                 rtnl_unlock();
  35                 kfree(offload);
  36                 return -EINVAL;
  37         }
  38
  39         prog->aux->offload = offload;
  40         list_add_tail(&offload->offloads, &bpf_prog_offload_devs);
  41         rtnl_unlock();
  42
  43         return 0;
  44 }
  45
  46 static int __bpf_offload_ndo(struct bpf_prog *prog, enum bpf_netdev_command cmd,
  47                              struct netdev_bpf *data)
  48 {
  49         struct net_device *netdev = prog->aux->offload->netdev;
  50
  51         ASSERT_RTNL();
  52
  53         if (!netdev)
  54                 return -ENODEV;
  55         if (!netdev->netdev_ops->ndo_bpf)
  56                 return -EOPNOTSUPP;
  57
  58         data->command = cmd;
  59
  60         return netdev->netdev_ops->ndo_bpf(netdev, data);
  61 }
  62
  63 int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env)
  64 {
  65         struct netdev_bpf data = {};
  66         int err;
  67
  68         data.verifier.prog = env->prog;
  69
  70         rtnl_lock();
  71         err = __bpf_offload_ndo(env->prog, BPF_OFFLOAD_VERIFIER_PREP, &data);
  72         if (err)
  73                 goto exit_unlock;
  74
  75         env->dev_ops = data.verifier.ops;
  76
  77         env->prog->aux->offload->dev_state = true;
  78         env->prog->aux->offload->verifier_running = true;
  79 exit_unlock:
  80         rtnl_unlock();
  81         return err;
  82 }
  83
  84 static void __bpf_prog_offload_destroy(struct bpf_prog *prog)
  85 {
  86         struct bpf_dev_offload *offload = prog->aux->offload;
  87         struct netdev_bpf data = {};
  88
  89         /* Caution - if netdev is destroyed before the program, this function
  90          * will be called twice.
  91          */
  92
  93         data.offload.prog = prog;
  94
  95         if (offload->verifier_running)
  96                 wait_event(offload->verifier_done, !offload->verifier_running);
  97
  98         if (offload->dev_state)
  99                 WARN_ON(__bpf_offload_ndo(prog, BPF_OFFLOAD_DESTROY, &data));
 100
 101         offload->dev_state = false;
 102         list_del_init(&offload->offloads);
 103         offload->netdev = NULL;
 104 }
 105
 106 void bpf_prog_offload_destroy(struct bpf_prog *prog)
 107 {
 108         struct bpf_dev_offload *offload = prog->aux->offload;
 109
 110         offload->verifier_running = false;
 111         wake_up(&offload->verifier_done);
 112
 113         rtnl_lock();
 114         __bpf_prog_offload_destroy(prog);
 115         rtnl_unlock();
 116
 117         kfree(offload);
 118 }
 119
 120 static int bpf_prog_offload_translate(struct bpf_prog *prog)
 121 {
 122         struct bpf_dev_offload *offload = prog->aux->offload;
 123         struct netdev_bpf data = {};
 124         int ret;
 125
 126         data.offload.prog = prog;
 127
 128         offload->verifier_running = false;
 129         wake_up(&offload->verifier_done);
 130
 131         rtnl_lock();
 132         ret = __bpf_offload_ndo(prog, BPF_OFFLOAD_TRANSLATE, &data);
 133         rtnl_unlock();
 134
 135         return ret;
 136 }
 137
 138 static unsigned int bpf_prog_warn_on_exec(const void *ctx,
 139                                           const struct bpf_insn *insn)
 140 {
 141         WARN(1, "attempt to execute device eBPF program on the host!");
 142         return 0;
 143 }
 144
 145 int bpf_prog_offload_compile(struct bpf_prog *prog)
 146 {
 147         prog->bpf_func = bpf_prog_warn_on_exec;
 148
 149         return bpf_prog_offload_translate(prog);
 150 }
 151
 152 const struct bpf_prog_ops bpf_offload_prog_ops = {
 153 };
 154
 155 static int bpf_offload_notification(struct notifier_block *notifier,
 156                                     ulong event, void *ptr)
 157 {
 158         struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
 159         struct bpf_dev_offload *offload, *tmp;
 160
 161         ASSERT_RTNL();
 162
 163         switch (event) {
 164         case NETDEV_UNREGISTER:
 165                 /* ignore namespace changes */
 166                 if (netdev->reg_state != NETREG_UNREGISTERING)
 167                         break;
 168
 169                 list_for_each_entry_safe(offload, tmp, &bpf_prog_offload_devs,
 170                                          offloads) {
 171                         if (offload->netdev == netdev)
 172                                 __bpf_prog_offload_destroy(offload->prog);
 173                 }
 174                 break;
 175         default:
 176                 break;
 177         }
 178         return NOTIFY_OK;
 179 }
 180
 181 static struct notifier_block bpf_offload_notifier = {
 182         .notifier_call = bpf_offload_notification,
 183 };
 184
 185 static int __init bpf_offload_init(void)
 186 {
 187         register_netdevice_notifier(&bpf_offload_notifier);
 188         return 0;
 189 }
 190
 191 subsys_initcall(bpf_offload_init);