mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
355 lines
8.6 KiB
355 lines
8.6 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
/* |
|
* Copyright (c) 2018 Facebook |
|
*/ |
|
#include <linux/bpf.h> |
|
#include <linux/err.h> |
|
#include <linux/sock_diag.h> |
|
#include <net/sock_reuseport.h> |
|
|
|
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) |
|
{ |
|
uintptr_t sk_user_data; |
|
|
|
write_lock_bh(&sk->sk_callback_lock); |
|
sk_user_data = (uintptr_t)sk->sk_user_data; |
|
if (sk_user_data & SK_USER_DATA_BPF) { |
|
struct sock __rcu **socks; |
|
|
|
socks = (void *)(sk_user_data & SK_USER_DATA_PTRMASK); |
|
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 int 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 triggerred 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 |
|
* referenceing 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; |
|
u64 array_size; |
|
|
|
if (!bpf_capable()) |
|
return ERR_PTR(-EPERM); |
|
|
|
array_size = sizeof(*array); |
|
array_size += (u64)attr->max_entries * sizeof(struct sock *); |
|
|
|
/* allocate all map elements and zero-initialize them */ |
|
array = bpf_map_area_alloc(array_size, 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 int |
|
reuseport_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: |
|
fput(socket->file); |
|
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 int reuseport_array_map_btf_id; |
|
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_btf_name = "reuseport_array", |
|
.map_btf_id = &reuseport_array_map_btf_id, |
|
};
|
|
|