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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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struct reuseport_array { struct bpf_map map; struct sock __rcu *ptrs[];};
static struct reuseport_array *reuseport_array(struct bpf_map *map){ return (struct reuseport_array *)map;}
/* The caller must hold the reuseport_lock */void bpf_sk_reuseport_detach(struct sock *sk){ struct sock __rcu **socks;
write_lock_bh(&sk->sk_callback_lock); socks = __locked_read_sk_user_data_with_flags(sk, SK_USER_DATA_BPF); if (socks) { WRITE_ONCE(sk->sk_user_data, NULL); /* * Do not move this NULL assignment outside of * sk->sk_callback_lock because there is * a race with reuseport_array_free() * which does not hold the reuseport_lock. */ RCU_INIT_POINTER(*socks, NULL); } write_unlock_bh(&sk->sk_callback_lock);}
static int reuseport_array_alloc_check(union bpf_attr *attr){ if (attr->value_size != sizeof(u32) && attr->value_size != sizeof(u64)) return -EINVAL;
return array_map_alloc_check(attr);}
static void *reuseport_array_lookup_elem(struct bpf_map *map, void *key){ struct reuseport_array *array = reuseport_array(map); u32 index = *(u32 *)key;
if (unlikely(index >= array->map.max_entries)) return NULL;
return rcu_dereference(array->ptrs[index]);}
/* Called from syscall only */static long reuseport_array_delete_elem(struct bpf_map *map, void *key){ struct reuseport_array *array = reuseport_array(map); u32 index = *(u32 *)key; struct sock *sk; int err;
if (index >= map->max_entries) return -E2BIG;
if (!rcu_access_pointer(array->ptrs[index])) return -ENOENT;
spin_lock_bh(&reuseport_lock);
sk = rcu_dereference_protected(array->ptrs[index], lockdep_is_held(&reuseport_lock)); if (sk) { write_lock_bh(&sk->sk_callback_lock); WRITE_ONCE(sk->sk_user_data, NULL); RCU_INIT_POINTER(array->ptrs[index], NULL); write_unlock_bh(&sk->sk_callback_lock); err = 0; } else { err = -ENOENT; }
spin_unlock_bh(&reuseport_lock);
return err;}
static void reuseport_array_free(struct bpf_map *map){ struct reuseport_array *array = reuseport_array(map); struct sock *sk; u32 i;
/* * ops->map_*_elem() will not be able to access this * array now. Hence, this function only races with * bpf_sk_reuseport_detach() which was triggered by * close() or disconnect(). * * This function and bpf_sk_reuseport_detach() are * both removing sk from "array". Who removes it * first does not matter. * * The only concern here is bpf_sk_reuseport_detach() * may access "array" which is being freed here. * bpf_sk_reuseport_detach() access this "array" * through sk->sk_user_data _and_ with sk->sk_callback_lock * held which is enough because this "array" is not freed * until all sk->sk_user_data has stopped referencing this "array". * * Hence, due to the above, taking "reuseport_lock" is not * needed here. */
/* * Since reuseport_lock is not taken, sk is accessed under * rcu_read_lock() */ rcu_read_lock(); for (i = 0; i < map->max_entries; i++) { sk = rcu_dereference(array->ptrs[i]); if (sk) { write_lock_bh(&sk->sk_callback_lock); /* * No need for WRITE_ONCE(). At this point, * no one is reading it without taking the * sk->sk_callback_lock. */ sk->sk_user_data = NULL; write_unlock_bh(&sk->sk_callback_lock); RCU_INIT_POINTER(array->ptrs[i], NULL); } } rcu_read_unlock();
/* * Once reaching here, all sk->sk_user_data is not * referencing this "array". "array" can be freed now. */ bpf_map_area_free(array);}
static struct bpf_map *reuseport_array_alloc(union bpf_attr *attr){ int numa_node = bpf_map_attr_numa_node(attr); struct reuseport_array *array;
/* allocate all map elements and zero-initialize them */ array = bpf_map_area_alloc(struct_size(array, ptrs, attr->max_entries), numa_node); if (!array) return ERR_PTR(-ENOMEM);
/* copy mandatory map attributes */ bpf_map_init_from_attr(&array->map, attr);
return &array->map;}
int bpf_fd_reuseport_array_lookup_elem(struct bpf_map *map, void *key, void *value){ struct sock *sk; int err;
if (map->value_size != sizeof(u64)) return -ENOSPC;
rcu_read_lock(); sk = reuseport_array_lookup_elem(map, key); if (sk) { *(u64 *)value = __sock_gen_cookie(sk); err = 0; } else { err = -ENOENT; } rcu_read_unlock();
return err;}
static intreuseport_array_update_check(const struct reuseport_array *array, const struct sock *nsk, const struct sock *osk, const struct sock_reuseport *nsk_reuse, u32 map_flags){ if (osk && map_flags == BPF_NOEXIST) return -EEXIST;
if (!osk && map_flags == BPF_EXIST) return -ENOENT;
if (nsk->sk_protocol != IPPROTO_UDP && nsk->sk_protocol != IPPROTO_TCP) return -ENOTSUPP;
if (nsk->sk_family != AF_INET && nsk->sk_family != AF_INET6) return -ENOTSUPP;
if (nsk->sk_type != SOCK_STREAM && nsk->sk_type != SOCK_DGRAM) return -ENOTSUPP;
/* * sk must be hashed (i.e. listening in the TCP case or binded * in the UDP case) and * it must also be a SO_REUSEPORT sk (i.e. reuse cannot be NULL). * * Also, sk will be used in bpf helper that is protected by * rcu_read_lock(). */ if (!sock_flag(nsk, SOCK_RCU_FREE) || !sk_hashed(nsk) || !nsk_reuse) return -EINVAL;
/* READ_ONCE because the sk->sk_callback_lock may not be held here */ if (READ_ONCE(nsk->sk_user_data)) return -EBUSY;
return 0;}
/* * Called from syscall only. * The "nsk" in the fd refcnt. * The "osk" and "reuse" are protected by reuseport_lock. */int bpf_fd_reuseport_array_update_elem(struct bpf_map *map, void *key, void *value, u64 map_flags){ struct reuseport_array *array = reuseport_array(map); struct sock *free_osk = NULL, *osk, *nsk; struct sock_reuseport *reuse; u32 index = *(u32 *)key; uintptr_t sk_user_data; struct socket *socket; int err, fd;
if (map_flags > BPF_EXIST) return -EINVAL;
if (index >= map->max_entries) return -E2BIG;
if (map->value_size == sizeof(u64)) { u64 fd64 = *(u64 *)value;
if (fd64 > S32_MAX) return -EINVAL; fd = fd64; } else { fd = *(int *)value; }
socket = sockfd_lookup(fd, &err); if (!socket) return err;
nsk = socket->sk; if (!nsk) { err = -EINVAL; goto put_file; }
/* Quick checks before taking reuseport_lock */ err = reuseport_array_update_check(array, nsk, rcu_access_pointer(array->ptrs[index]), rcu_access_pointer(nsk->sk_reuseport_cb), map_flags); if (err) goto put_file;
spin_lock_bh(&reuseport_lock); /* * Some of the checks only need reuseport_lock * but it is done under sk_callback_lock also * for simplicity reason. */ write_lock_bh(&nsk->sk_callback_lock);
osk = rcu_dereference_protected(array->ptrs[index], lockdep_is_held(&reuseport_lock)); reuse = rcu_dereference_protected(nsk->sk_reuseport_cb, lockdep_is_held(&reuseport_lock)); err = reuseport_array_update_check(array, nsk, osk, reuse, map_flags); if (err) goto put_file_unlock;
sk_user_data = (uintptr_t)&array->ptrs[index] | SK_USER_DATA_NOCOPY | SK_USER_DATA_BPF; WRITE_ONCE(nsk->sk_user_data, (void *)sk_user_data); rcu_assign_pointer(array->ptrs[index], nsk); free_osk = osk; err = 0;
put_file_unlock: write_unlock_bh(&nsk->sk_callback_lock);
if (free_osk) { write_lock_bh(&free_osk->sk_callback_lock); WRITE_ONCE(free_osk->sk_user_data, NULL); write_unlock_bh(&free_osk->sk_callback_lock); }
spin_unlock_bh(&reuseport_lock);put_file: sockfd_put(socket); return err;}
/* Called from syscall */static int reuseport_array_get_next_key(struct bpf_map *map, void *key, void *next_key){ struct reuseport_array *array = reuseport_array(map); u32 index = key ? *(u32 *)key : U32_MAX; u32 *next = (u32 *)next_key;
if (index >= array->map.max_entries) { *next = 0; return 0; }
if (index == array->map.max_entries - 1) return -ENOENT;
*next = index + 1; return 0;}
static u64 reuseport_array_mem_usage(const struct bpf_map *map){ struct reuseport_array *array;
return struct_size(array, ptrs, map->max_entries);}
BTF_ID_LIST_SINGLE(reuseport_array_map_btf_ids, struct, reuseport_array)const struct bpf_map_ops reuseport_array_ops = { .map_meta_equal = bpf_map_meta_equal, .map_alloc_check = reuseport_array_alloc_check, .map_alloc = reuseport_array_alloc, .map_free = reuseport_array_free, .map_lookup_elem = reuseport_array_lookup_elem, .map_get_next_key = reuseport_array_get_next_key, .map_delete_elem = reuseport_array_delete_elem, .map_mem_usage = reuseport_array_mem_usage, .map_btf_id = &reuseport_array_map_btf_ids[0],};