net/xdp/xskmap.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /* XSKMAP used for AF_XDP sockets
  * Copyright(c) 2018 Intel Corporation.
  */

 #include <linux/bpf.h>
 #include <linux/filter.h>
 #include <linux/capability.h>
 #include <net/xdp_sock.h>
 #include <linux/slab.h>
 #include <linux/sched.h>

 #include "xsk.h"

 static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map,
 					       struct xdp_sock __rcu **map_entry)
 {
 	struct xsk_map_node *node;

 	node = bpf_map_kzalloc(&map->map, sizeof(*node),
 			       GFP_ATOMIC | __GFP_NOWARN);
 	if (!node)
 		return ERR_PTR(-ENOMEM);

 	bpf_map_inc(&map->map);

 	node->map = map;
 	node->map_entry = map_entry;
 	return node;
 }

 static void xsk_map_node_free(struct xsk_map_node *node)
 {
 	bpf_map_put(&node->map->map);
 	kfree(node);
 }

 static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node)
 {
 	spin_lock_bh(&xs->map_list_lock);
 	list_add_tail(&node->node, &xs->map_list);
 	spin_unlock_bh(&xs->map_list_lock);
 }

 static void xsk_map_sock_delete(struct xdp_sock *xs,
 				struct xdp_sock __rcu **map_entry)
 {
 	struct xsk_map_node *n, *tmp;

 	spin_lock_bh(&xs->map_list_lock);
 	list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
 		if (map_entry == n->map_entry) {
 			list_del(&n->node);
 			xsk_map_node_free(n);
 		}
 	}
 	spin_unlock_bh(&xs->map_list_lock);
 }

 static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
 {
 	struct xsk_map *m;
 	int numa_node;
 	u64 size;

 	if (!capable(CAP_NET_ADMIN))
 		return ERR_PTR(-EPERM);

 	if (attr->max_entries == 0 || attr->key_size != 4 ||
 	    attr->value_size != 4 ||
 	    attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
 		return ERR_PTR(-EINVAL);

 	numa_node = bpf_map_attr_numa_node(attr);
 	size = struct_size(m, xsk_map, attr->max_entries);

 	m = bpf_map_area_alloc(size, numa_node);
 	if (!m)
 		return ERR_PTR(-ENOMEM);

 	bpf_map_init_from_attr(&m->map, attr);
 	spin_lock_init(&m->lock);

 	return &m->map;
 }

 static void xsk_map_free(struct bpf_map *map)
 {
 	struct xsk_map *m = container_of(map, struct xsk_map, map);

 	synchronize_net();
 	bpf_map_area_free(m);
 }

 static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
 {
 	struct xsk_map *m = container_of(map, struct xsk_map, map);
 	u32 index = key ? *(u32 *)key : U32_MAX;
 	u32 *next = next_key;

 	if (index >= m->map.max_entries) {
 		*next = 0;
 		return 0;
 	}

 	if (index == m->map.max_entries - 1)
 		return -ENOENT;
 	*next = index + 1;
 	return 0;
 }

 static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
 {
 	const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2;
 	struct bpf_insn *insn = insn_buf;

 	*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
 	*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
 	*insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *)));
 	*insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map));
 	*insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp);
 	*insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0);
 	*insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
 	*insn++ = BPF_MOV64_IMM(ret, 0);
 	return insn - insn_buf;
 }

 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
  * by local_bh_disable() (from XDP calls inside NAPI). The
  * rcu_read_lock_bh_held() below makes lockdep accept both.
  */
 static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
 {
 	struct xsk_map *m = container_of(map, struct xsk_map, map);

 	if (key >= map->max_entries)
 		return NULL;

 	return rcu_dereference_check(m->xsk_map[key], rcu_read_lock_bh_held());
 }

 static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
 {
 	return __xsk_map_lookup_elem(map, *(u32 *)key);
 }

 static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }

 static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
 			       u64 map_flags)
 {
 	struct xsk_map *m = container_of(map, struct xsk_map, map);
 	struct xdp_sock __rcu **map_entry;
 	struct xdp_sock *xs, *old_xs;
 	u32 i = *(u32 *)key, fd = *(u32 *)value;
 	struct xsk_map_node *node;
 	struct socket *sock;
 	int err;

 	if (unlikely(map_flags > BPF_EXIST))
 		return -EINVAL;
 	if (unlikely(i >= m->map.max_entries))
 		return -E2BIG;

 	sock = sockfd_lookup(fd, &err);
 	if (!sock)
 		return err;

 	if (sock->sk->sk_family != PF_XDP) {
 		sockfd_put(sock);
 		return -EOPNOTSUPP;
 	}

 	xs = (struct xdp_sock *)sock->sk;

 	map_entry = &m->xsk_map[i];
 	node = xsk_map_node_alloc(m, map_entry);
 	if (IS_ERR(node)) {
 		sockfd_put(sock);
 		return PTR_ERR(node);
 	}

 	spin_lock_bh(&m->lock);
 	old_xs = rcu_dereference_protected(*map_entry, lockdep_is_held(&m->lock));
 	if (old_xs == xs) {
 		err = 0;
 		goto out;
 	} else if (old_xs && map_flags == BPF_NOEXIST) {
 		err = -EEXIST;
 		goto out;
 	} else if (!old_xs && map_flags == BPF_EXIST) {
 		err = -ENOENT;
 		goto out;
 	}
 	xsk_map_sock_add(xs, node);
 	rcu_assign_pointer(*map_entry, xs);
 	if (old_xs)
 		xsk_map_sock_delete(old_xs, map_entry);
 	spin_unlock_bh(&m->lock);
 	sockfd_put(sock);
 	return 0;

 out:
 	spin_unlock_bh(&m->lock);
 	sockfd_put(sock);
 	xsk_map_node_free(node);
 	return err;
 }

 static int xsk_map_delete_elem(struct bpf_map *map, void *key)
 {
 	struct xsk_map *m = container_of(map, struct xsk_map, map);
 	struct xdp_sock __rcu **map_entry;
 	struct xdp_sock *old_xs;
 	int k = *(u32 *)key;

 	if (k >= map->max_entries)
 		return -EINVAL;

 	spin_lock_bh(&m->lock);
 	map_entry = &m->xsk_map[k];
 	old_xs = unrcu_pointer(xchg(map_entry, NULL));
 	if (old_xs)
 		xsk_map_sock_delete(old_xs, map_entry);
 	spin_unlock_bh(&m->lock);

 	return 0;
 }

 static int xsk_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
 {
 	return __bpf_xdp_redirect_map(map, ifindex, flags, 0,
 				      __xsk_map_lookup_elem);
 }

 void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
 			     struct xdp_sock __rcu **map_entry)
 {
 	spin_lock_bh(&map->lock);
 	if (rcu_access_pointer(*map_entry) == xs) {
 		rcu_assign_pointer(*map_entry, NULL);
 		xsk_map_sock_delete(xs, map_entry);
 	}
 	spin_unlock_bh(&map->lock);
 }

 static bool xsk_map_meta_equal(const struct bpf_map *meta0,
 			       const struct bpf_map *meta1)
 {
 	return meta0->max_entries == meta1->max_entries &&
 		bpf_map_meta_equal(meta0, meta1);
 }

 static int xsk_map_btf_id;
 const struct bpf_map_ops xsk_map_ops = {
 	.map_meta_equal = xsk_map_meta_equal,
 	.map_alloc = xsk_map_alloc,
 	.map_free = xsk_map_free,
 	.map_get_next_key = xsk_map_get_next_key,
 	.map_lookup_elem = xsk_map_lookup_elem,
 	.map_gen_lookup = xsk_map_gen_lookup,
 	.map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
 	.map_update_elem = xsk_map_update_elem,
 	.map_delete_elem = xsk_map_delete_elem,
 	.map_check_btf = map_check_no_btf,
 	.map_btf_name = "xsk_map",
 	.map_btf_id = &xsk_map_btf_id,
 	.map_redirect = xsk_map_redirect,
 };
	// SPDX-License-Identifier: GPL-2.0
	/* XSKMAP used for AF_XDP sockets
	* Copyright(c) 2018 Intel Corporation.
	*/

	#include <linux/bpf.h>
	#include <linux/filter.h>
	#include <linux/capability.h>
	#include <net/xdp_sock.h>
	#include <linux/slab.h>
	#include <linux/sched.h>

	#include "xsk.h"

	static struct xsk_map_node xsk_map_node_alloc(struct xsk_map map,
	struct xdp_sock __rcu **map_entry)
	{
	struct xsk_map_node *node;

	node = bpf_map_kzalloc(&map->map, sizeof(*node),
	GFP_ATOMIC \| __GFP_NOWARN);
	if (!node)
	return ERR_PTR(-ENOMEM);

	bpf_map_inc(&map->map);

	node->map = map;
	node->map_entry = map_entry;
	return node;
	}

	static void xsk_map_node_free(struct xsk_map_node *node)
	{
	bpf_map_put(&node->map->map);
	kfree(node);
	}

	static void xsk_map_sock_add(struct xdp_sock xs, struct xsk_map_node node)
	{
	spin_lock_bh(&xs->map_list_lock);
	list_add_tail(&node->node, &xs->map_list);
	spin_unlock_bh(&xs->map_list_lock);
	}

	static void xsk_map_sock_delete(struct xdp_sock *xs,
	struct xdp_sock __rcu **map_entry)
	{
	struct xsk_map_node n, tmp;

	spin_lock_bh(&xs->map_list_lock);
	list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
	if (map_entry == n->map_entry) {
	list_del(&n->node);
	xsk_map_node_free(n);
	}
	}
	spin_unlock_bh(&xs->map_list_lock);
	}

	static struct bpf_map xsk_map_alloc(union bpf_attr attr)
	{
	struct xsk_map *m;
	int numa_node;
	u64 size;

	if (!capable(CAP_NET_ADMIN))
	return ERR_PTR(-EPERM);

	if (attr->max_entries == 0 \|\| attr->key_size != 4 \|\|
	attr->value_size != 4 \|\|
	attr->map_flags & ~(BPF_F_NUMA_NODE \| BPF_F_RDONLY \| BPF_F_WRONLY))
	return ERR_PTR(-EINVAL);

	numa_node = bpf_map_attr_numa_node(attr);
	size = struct_size(m, xsk_map, attr->max_entries);

	m = bpf_map_area_alloc(size, numa_node);
	if (!m)
	return ERR_PTR(-ENOMEM);

	bpf_map_init_from_attr(&m->map, attr);
	spin_lock_init(&m->lock);

	return &m->map;
	}

	static void xsk_map_free(struct bpf_map *map)
	{
	struct xsk_map *m = container_of(map, struct xsk_map, map);

	synchronize_net();
	bpf_map_area_free(m);
	}

	static int xsk_map_get_next_key(struct bpf_map map, void key, void *next_key)
	{
	struct xsk_map *m = container_of(map, struct xsk_map, map);
	u32 index = key ? (u32 )key : U32_MAX;
	u32 *next = next_key;

	if (index >= m->map.max_entries) {
	*next = 0;
	return 0;
	}

	if (index == m->map.max_entries - 1)
	return -ENOENT;
	*next = index + 1;
	return 0;
	}

	static int xsk_map_gen_lookup(struct bpf_map map, struct bpf_insn insn_buf)
	{
	const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2;
	struct bpf_insn *insn = insn_buf;

	*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
	*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
	insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock )));
	*insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map));
	*insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp);
	insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock ), ret, ret, 0);
	*insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
	*insn++ = BPF_MOV64_IMM(ret, 0);
	return insn - insn_buf;
	}

	/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
	* by local_bh_disable() (from XDP calls inside NAPI). The
	* rcu_read_lock_bh_held() below makes lockdep accept both.
	*/
	static void __xsk_map_lookup_elem(struct bpf_map map, u32 key)
	{
	struct xsk_map *m = container_of(map, struct xsk_map, map);

	if (key >= map->max_entries)
	return NULL;

	return rcu_dereference_check(m->xsk_map[key], rcu_read_lock_bh_held());
	}

	static void xsk_map_lookup_elem(struct bpf_map map, void *key)
	{
	return __xsk_map_lookup_elem(map, (u32 )key);
	}

	static void xsk_map_lookup_elem_sys_only(struct bpf_map map, void *key)
	{
	return ERR_PTR(-EOPNOTSUPP);
	}

	static int xsk_map_update_elem(struct bpf_map map, void key, void *value,
	u64 map_flags)
	{
	struct xsk_map *m = container_of(map, struct xsk_map, map);
	struct xdp_sock __rcu **map_entry;
	struct xdp_sock xs, old_xs;
	u32 i = (u32 )key, fd = (u32 )value;
	struct xsk_map_node *node;
	struct socket *sock;
	int err;

	if (unlikely(map_flags > BPF_EXIST))
	return -EINVAL;
	if (unlikely(i >= m->map.max_entries))
	return -E2BIG;

	sock = sockfd_lookup(fd, &err);
	if (!sock)
	return err;

	if (sock->sk->sk_family != PF_XDP) {
	sockfd_put(sock);
	return -EOPNOTSUPP;
	}

	xs = (struct xdp_sock *)sock->sk;

	map_entry = &m->xsk_map[i];
	node = xsk_map_node_alloc(m, map_entry);
	if (IS_ERR(node)) {
	sockfd_put(sock);
	return PTR_ERR(node);
	}

	spin_lock_bh(&m->lock);
	old_xs = rcu_dereference_protected(*map_entry, lockdep_is_held(&m->lock));
	if (old_xs == xs) {
	err = 0;
	goto out;
	} else if (old_xs && map_flags == BPF_NOEXIST) {
	err = -EEXIST;
	goto out;
	} else if (!old_xs && map_flags == BPF_EXIST) {
	err = -ENOENT;
	goto out;
	}
	xsk_map_sock_add(xs, node);
	rcu_assign_pointer(*map_entry, xs);
	if (old_xs)
	xsk_map_sock_delete(old_xs, map_entry);
	spin_unlock_bh(&m->lock);
	sockfd_put(sock);
	return 0;

	out:
	spin_unlock_bh(&m->lock);
	sockfd_put(sock);
	xsk_map_node_free(node);
	return err;
	}

	static int xsk_map_delete_elem(struct bpf_map map, void key)
	{
	struct xsk_map *m = container_of(map, struct xsk_map, map);
	struct xdp_sock __rcu **map_entry;
	struct xdp_sock *old_xs;
	int k = (u32 )key;

	if (k >= map->max_entries)
	return -EINVAL;

	spin_lock_bh(&m->lock);
	map_entry = &m->xsk_map[k];
	old_xs = unrcu_pointer(xchg(map_entry, NULL));
	if (old_xs)
	xsk_map_sock_delete(old_xs, map_entry);
	spin_unlock_bh(&m->lock);

	return 0;
	}

	static int xsk_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
	{
	return __bpf_xdp_redirect_map(map, ifindex, flags, 0,
	__xsk_map_lookup_elem);
	}

	void xsk_map_try_sock_delete(struct xsk_map map, struct xdp_sock xs,
	struct xdp_sock __rcu **map_entry)
	{
	spin_lock_bh(&map->lock);
	if (rcu_access_pointer(*map_entry) == xs) {
	rcu_assign_pointer(*map_entry, NULL);
	xsk_map_sock_delete(xs, map_entry);
	}
	spin_unlock_bh(&map->lock);
	}

	static bool xsk_map_meta_equal(const struct bpf_map *meta0,
	const struct bpf_map *meta1)
	{
	return meta0->max_entries == meta1->max_entries &&
	bpf_map_meta_equal(meta0, meta1);
	}

	static int xsk_map_btf_id;
	const struct bpf_map_ops xsk_map_ops = {
	.map_meta_equal = xsk_map_meta_equal,
	.map_alloc = xsk_map_alloc,
	.map_free = xsk_map_free,
	.map_get_next_key = xsk_map_get_next_key,
	.map_lookup_elem = xsk_map_lookup_elem,
	.map_gen_lookup = xsk_map_gen_lookup,
	.map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
	.map_update_elem = xsk_map_update_elem,
	.map_delete_elem = xsk_map_delete_elem,
	.map_check_btf = map_check_no_btf,
	.map_btf_name = "xsk_map",
	.map_btf_id = &xsk_map_btf_id,
	.map_redirect = xsk_map_redirect,
	};