[net-next,02/15] bpf: offload: add infrastructure for loading programs for a specific netdev

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 520aeebe0d93..e45d43f9ec92 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -15,6 +15,7 @@ 
 #include <linux/err.h>
 #include <linux/rbtree_latch.h>
 #include <linux/numa.h>
+#include <linux/wait.h>
 
 struct perf_event;
 struct bpf_prog;
@@ -182,6 +183,16 @@  struct bpf_verifier_ops {
 				  struct bpf_prog *prog, u32 *target_size);
 };
 
+struct bpf_dev_offload {
+	struct bpf_prog		*prog;
+	struct net_device	*netdev;
+	void			*dev_priv;
+	struct list_head	offloads;
+	bool			dev_state;
+	bool			verifier_running;
+	wait_queue_head_t	verifier_done;
+};
+
 struct bpf_prog_aux {
 	atomic_t refcnt;
 	u32 used_map_cnt;
@@ -199,6 +210,7 @@  struct bpf_prog_aux {
 #ifdef CONFIG_SECURITY
 	void *security;
 #endif
+	struct bpf_dev_offload *offload;
 	union {
 		struct work_struct work;
 		struct rcu_head	rcu;
@@ -317,6 +329,7 @@  extern const struct file_operations bpf_prog_fops;
 #undef BPF_PROG_TYPE
 #undef BPF_MAP_TYPE
 
+extern const struct bpf_prog_ops bpf_offload_prog_ops;
 extern const struct bpf_verifier_ops tc_cls_act_analyzer_ops;
 extern const struct bpf_verifier_ops xdp_analyzer_ops;
 
@@ -491,6 +504,29 @@  static inline int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu,
 }
 #endif /* CONFIG_BPF_SYSCALL */
 
+int bpf_prog_offload_compile(struct bpf_prog *prog);
+void bpf_prog_offload_destroy(struct bpf_prog *prog);
+
+#if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL)
+int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr);
+
+static inline bool bpf_prog_is_dev_bound(struct bpf_prog_aux *aux)
+{
+	return aux->offload;
+}
+#else
+static inline int bpf_prog_offload_init(struct bpf_prog *prog,
+					union bpf_attr *attr)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline bool bpf_prog_is_dev_bound(struct bpf_prog_aux *aux)
+{
+	return false;
+}
+#endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */
+
 #if defined(CONFIG_STREAM_PARSER) && defined(CONFIG_BPF_SYSCALL)
 struct sock  *__sock_map_lookup_elem(struct bpf_map *map, u32 key);
 int sock_map_prog(struct bpf_map *map, struct bpf_prog *prog, u32 type);
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 3b0976aaac75..e45011dbc02d 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -153,6 +153,7 @@  struct bpf_verifier_env {
 	struct bpf_verifier_state *cur_state; /* current verifier state */
 	struct bpf_verifier_state_list **explored_states; /* search pruning optimization */
 	const struct bpf_ext_analyzer_ops *analyzer_ops; /* external analyzer ops */
+	const struct bpf_ext_analyzer_ops *dev_ops; /* device analyzer ops */
 	void *analyzer_priv; /* pointer to external analyzer's private data */
 	struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
 	u32 used_map_cnt;		/* number of used maps */
@@ -169,6 +170,15 @@  static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env)
 	return env->cur_state->regs;
 }
 
+#if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL)
+int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env);
+#else
+int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
 		 void *priv);
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 331378a0a0a1..282d6fc2a60a 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -797,8 +797,13 @@  enum bpf_netdev_command {
 	 * is equivalent to XDP_ATTACHED_DRV.
 	 */
 	XDP_QUERY_PROG,
+	/* BPF program for offload callbacks, invoked at program load time. */
+	BPF_OFFLOAD_VERIFIER_PREP,
+	BPF_OFFLOAD_TRANSLATE,
+	BPF_OFFLOAD_DESTROY,
 };
 
+struct bpf_ext_analyzer_ops;
 struct netlink_ext_ack;
 
 struct netdev_bpf {
@@ -815,6 +820,15 @@  struct netdev_bpf {
 			u8 prog_attached;
 			u32 prog_id;
 		};
+		/* BPF_OFFLOAD_VERIFIER_PREP */
+		struct {
+			struct bpf_prog *prog;
+			const struct bpf_ext_analyzer_ops *ops; /* callee set */
+		} verifier;
+		/* BPF_OFFLOAD_TRANSLATE, BPF_OFFLOAD_DESTROY */
+		struct {
+			struct bpf_prog *prog;
+		} offload;
 	};
 };
 
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 7cebba491011..727a3dba13e6 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -259,6 +259,7 @@  union bpf_attr {
 		__u32		kern_version;	/* checked when prog_type=kprobe */
 		__u32		prog_flags;
 		char		prog_name[BPF_OBJ_NAME_LEN];
+		__u32		prog_target_ifindex;	/* ifindex of netdev to prep for */
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_* commands */
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index e597daae6120..05fef663ba16 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -6,6 +6,7 @@  obj-$(CONFIG_BPF_SYSCALL) += disasm.o
 ifeq ($(CONFIG_NET),y)
 obj-$(CONFIG_BPF_SYSCALL) += devmap.o
 obj-$(CONFIG_BPF_SYSCALL) += cpumap.o
+obj-$(CONFIG_BPF_SYSCALL) += offload.o
 ifeq ($(CONFIG_STREAM_PARSER),y)
 obj-$(CONFIG_BPF_SYSCALL) += sockmap.o
 endif
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 7fe448799d76..8a6c37762330 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1380,7 +1380,13 @@  struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
 	 * valid program, which in this case would simply not
 	 * be JITed, but falls back to the interpreter.
 	 */
-	fp = bpf_int_jit_compile(fp);
+	if (!bpf_prog_is_dev_bound(fp->aux)) {
+		fp = bpf_int_jit_compile(fp);
+	} else {
+		*err = bpf_prog_offload_compile(fp);
+		if (*err)
+			return fp;
+	}
 	bpf_prog_lock_ro(fp);
 
 	/* The tail call compatibility check can only be done at
@@ -1549,6 +1555,8 @@  static void bpf_prog_free_deferred(struct work_struct *work)
 	struct bpf_prog_aux *aux;
 
 	aux = container_of(work, struct bpf_prog_aux, work);
+	if (bpf_prog_is_dev_bound(aux))
+		bpf_prog_offload_destroy(aux->prog);
 	bpf_jit_free(aux->prog);
 }
 
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
new file mode 100644
index 000000000000..47436ece9b1d
--- /dev/null
+++ b/kernel/bpf/offload.c
@@ -0,0 +1,182 @@ 
+#include <asm/bug.h>
+#include <linux/bpf.h>
+#include <linux/bpf_verifier.h>
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/printk.h>
+#include <linux/rtnetlink.h>
+
+/* protected by RTNL */
+static LIST_HEAD(bpf_prog_offload_devs);
+
+int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr)
+{
+	struct net *net = current->nsproxy->net_ns;
+	struct bpf_dev_offload *offload;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (attr->prog_flags)
+		return -EINVAL;
+
+	offload = kzalloc(sizeof(*offload), GFP_USER);
+	if (!offload)
+		return -ENOMEM;
+
+	offload->prog = prog;
+	init_waitqueue_head(&offload->verifier_done);
+
+	rtnl_lock();
+	offload->netdev = __dev_get_by_index(net, attr->prog_target_ifindex);
+	if (!offload->netdev) {
+		rtnl_unlock();
+		kfree(offload);
+		return -EINVAL;
+	}
+
+	prog->aux->offload = offload;
+	list_add_tail(&offload->offloads, &bpf_prog_offload_devs);
+	rtnl_unlock();
+
+	return 0;
+}
+
+static int __bpf_offload_ndo(struct bpf_prog *prog, enum bpf_netdev_command cmd,
+			     struct netdev_bpf *data)
+{
+	struct net_device *netdev = prog->aux->offload->netdev;
+
+	ASSERT_RTNL();
+
+	if (!netdev)
+		return -ENODEV;
+	if (!netdev->netdev_ops->ndo_bpf)
+		return -EOPNOTSUPP;
+
+	data->command = cmd;
+
+	return netdev->netdev_ops->ndo_bpf(netdev, data);
+}
+
+int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env)
+{
+	struct netdev_bpf data = {};
+	int err;
+
+	data.verifier.prog = env->prog;
+
+	rtnl_lock();
+	err = __bpf_offload_ndo(env->prog, BPF_OFFLOAD_VERIFIER_PREP, &data);
+	if (err)
+		goto exit_unlock;
+
+	env->dev_ops = data.verifier.ops;
+
+	env->prog->aux->offload->dev_state = true;
+	env->prog->aux->offload->verifier_running = true;
+exit_unlock:
+	rtnl_unlock();
+	return err;
+}
+
+static void __bpf_prog_offload_destroy(struct bpf_prog *prog)
+{
+	struct bpf_dev_offload *offload = prog->aux->offload;
+	struct netdev_bpf data = {};
+
+	data.offload.prog = prog;
+
+	if (offload->verifier_running)
+		wait_event(offload->verifier_done, !offload->verifier_running);
+
+	if (offload->dev_state)
+		WARN_ON(__bpf_offload_ndo(prog, BPF_OFFLOAD_DESTROY, &data));
+
+	offload->dev_state = false;
+	list_del_init(&offload->offloads);
+	offload->netdev = NULL;
+}
+
+void bpf_prog_offload_destroy(struct bpf_prog *prog)
+{
+	struct bpf_dev_offload *offload = prog->aux->offload;
+
+	offload->verifier_running = false;
+	wake_up(&offload->verifier_done);
+
+	rtnl_lock();
+	__bpf_prog_offload_destroy(prog);
+	rtnl_unlock();
+
+	kfree(offload);
+}
+
+static int bpf_prog_offload_translate(struct bpf_prog *prog)
+{
+	struct bpf_dev_offload *offload = prog->aux->offload;
+	struct netdev_bpf data = {};
+	int ret;
+
+	data.offload.prog = prog;
+
+	offload->verifier_running = false;
+	wake_up(&offload->verifier_done);
+
+	rtnl_lock();
+	ret = __bpf_offload_ndo(prog, BPF_OFFLOAD_TRANSLATE, &data);
+	rtnl_unlock();
+
+	return ret;
+}
+
+static unsigned int bpf_prog_warn_on_exec(const void *ctx,
+					  const struct bpf_insn *insn)
+{
+	WARN(1, "attempt to execute device eBPF program on the host!");
+	return 0;
+}
+
+int bpf_prog_offload_compile(struct bpf_prog *prog)
+{
+	prog->bpf_func = bpf_prog_warn_on_exec;
+
+	return bpf_prog_offload_translate(prog);
+}
+
+const struct bpf_prog_ops bpf_offload_prog_ops = {
+};
+
+static int bpf_offload_notification(struct notifier_block *notifier,
+				    ulong event, void *ptr)
+{
+	struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
+	struct bpf_dev_offload *offload, *tmp;
+
+	ASSERT_RTNL();
+
+	switch (event) {
+	case NETDEV_UNREGISTER:
+		list_for_each_entry_safe(offload, tmp, &bpf_prog_offload_devs,
+					 offloads) {
+			if (offload->netdev == netdev)
+				__bpf_prog_offload_destroy(offload->prog);
+		}
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block bpf_offload_notifier = {
+	.notifier_call = bpf_offload_notification,
+};
+
+static int __init bpf_offload_init(void)
+{
+	register_netdevice_notifier(&bpf_offload_notifier);
+	return 0;
+}
+
+subsys_initcall(bpf_offload_init);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 323be2473c4b..1574b9f0f24e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -824,7 +824,10 @@  static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
 	if (type >= ARRAY_SIZE(bpf_prog_types) || !bpf_prog_types[type])
 		return -EINVAL;
 
-	prog->aux->ops = bpf_prog_types[type];
+	if (!bpf_prog_is_dev_bound(prog->aux))
+		prog->aux->ops = bpf_prog_types[type];
+	else
+		prog->aux->ops = &bpf_offload_prog_ops;
 	prog->type = type;
 	return 0;
 }
@@ -1054,7 +1057,7 @@  struct bpf_prog *bpf_prog_inc_not_zero(struct bpf_prog *prog)
 }
 EXPORT_SYMBOL_GPL(bpf_prog_inc_not_zero);
 
-static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *type)
+static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *attach_type)
 {
 	struct fd f = fdget(ufd);
 	struct bpf_prog *prog;
@@ -1062,7 +1065,7 @@  static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *type)
 	prog = ____bpf_prog_get(f);
 	if (IS_ERR(prog))
 		return prog;
-	if (type && prog->type != *type) {
+	if (attach_type && (prog->type != *attach_type || prog->aux->offload)) {
 		prog = ERR_PTR(-EINVAL);
 		goto out;
 	}
@@ -1089,7 +1092,7 @@  struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type)
 EXPORT_SYMBOL_GPL(bpf_prog_get_type);
 
 /* last field in 'union bpf_attr' used by this command */
-#define	BPF_PROG_LOAD_LAST_FIELD prog_name
+#define	BPF_PROG_LOAD_LAST_FIELD prog_target_ifindex
 
 static int bpf_prog_load(union bpf_attr *attr)
 {
@@ -1152,6 +1155,12 @@  static int bpf_prog_load(union bpf_attr *attr)
 	atomic_set(&prog->aux->refcnt, 1);
 	prog->gpl_compatible = is_gpl ? 1 : 0;
 
+	if (attr->prog_target_ifindex) {
+		err = bpf_prog_offload_init(prog, attr);
+		if (err)
+			goto free_prog;
+	}
+
 	/* find program type: socket_filter vs tracing_filter */
 	err = find_prog_type(type, prog);
 	if (err < 0)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index ab5aa5497666..5d20406239b1 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3736,10 +3736,13 @@  static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 static int ext_analyzer_insn_hook(struct bpf_verifier_env *env,
 				  int insn_idx, int prev_insn_idx)
 {
-	if (!env->analyzer_ops || !env->analyzer_ops->insn_hook)
-		return 0;
+	if (env->analyzer_ops && env->analyzer_ops->insn_hook)
+		return env->analyzer_ops->insn_hook(env, insn_idx,
+						    prev_insn_idx);
+	if (env->dev_ops && env->dev_ops->insn_hook)
+		return env->dev_ops->insn_hook(env, insn_idx, prev_insn_idx);
 
-	return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx);
+	return 0;
 }
 
 static int do_check(struct bpf_verifier_env *env)
@@ -4516,6 +4519,12 @@  int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
 	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
 		env->strict_alignment = true;
 
+	if (env->prog->aux->offload) {
+		ret = bpf_prog_offload_verifier_prep(env);
+		if (ret)
+			goto err_unlock;
+	}
+
 	ret = replace_map_fd_with_map_ptr(env);
 	if (ret < 0)
 		goto skip_full_check;