linux/net/ipv4/tcp_bpf.c
John Fastabend 5fa2ca7c4a bpf, tcp: correctly handle DONT_WAIT flags and timeo == 0
The tcp_bpf_wait_data() routine needs to check timeo != 0 before
calling sk_wait_event() otherwise we may see unexpected stalls
on receiver.

Arika did all the leg work here I just formatted, posted and ran
a few tests.

Fixes: 604326b41a ("bpf, sockmap: convert to generic sk_msg interface")
Reported-by: Arika Chen <eaglesora@gmail.com>
Suggested-by: Arika Chen <eaglesora@gmail.com>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-05-16 01:36:13 +02:00

693 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2017 - 2018 Covalent IO, Inc. http://covalent.io */
#include <linux/skmsg.h>
#include <linux/filter.h>
#include <linux/bpf.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <net/inet_common.h>
#include <net/tls.h>
static bool tcp_bpf_stream_read(const struct sock *sk)
{
struct sk_psock *psock;
bool empty = true;
rcu_read_lock();
psock = sk_psock(sk);
if (likely(psock))
empty = list_empty(&psock->ingress_msg);
rcu_read_unlock();
return !empty;
}
static int tcp_bpf_wait_data(struct sock *sk, struct sk_psock *psock,
int flags, long timeo, int *err)
{
DEFINE_WAIT_FUNC(wait, woken_wake_function);
int ret = 0;
if (!timeo)
return ret;
add_wait_queue(sk_sleep(sk), &wait);
sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
ret = sk_wait_event(sk, &timeo,
!list_empty(&psock->ingress_msg) ||
!skb_queue_empty(&sk->sk_receive_queue), &wait);
sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
remove_wait_queue(sk_sleep(sk), &wait);
return ret;
}
int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
struct msghdr *msg, int len, int flags)
{
struct iov_iter *iter = &msg->msg_iter;
int peek = flags & MSG_PEEK;
int i, ret, copied = 0;
struct sk_msg *msg_rx;
msg_rx = list_first_entry_or_null(&psock->ingress_msg,
struct sk_msg, list);
while (copied != len) {
struct scatterlist *sge;
if (unlikely(!msg_rx))
break;
i = msg_rx->sg.start;
do {
struct page *page;
int copy;
sge = sk_msg_elem(msg_rx, i);
copy = sge->length;
page = sg_page(sge);
if (copied + copy > len)
copy = len - copied;
ret = copy_page_to_iter(page, sge->offset, copy, iter);
if (ret != copy) {
msg_rx->sg.start = i;
return -EFAULT;
}
copied += copy;
if (likely(!peek)) {
sge->offset += copy;
sge->length -= copy;
sk_mem_uncharge(sk, copy);
msg_rx->sg.size -= copy;
if (!sge->length) {
sk_msg_iter_var_next(i);
if (!msg_rx->skb)
put_page(page);
}
} else {
sk_msg_iter_var_next(i);
}
if (copied == len)
break;
} while (i != msg_rx->sg.end);
if (unlikely(peek)) {
msg_rx = list_next_entry(msg_rx, list);
continue;
}
msg_rx->sg.start = i;
if (!sge->length && msg_rx->sg.start == msg_rx->sg.end) {
list_del(&msg_rx->list);
if (msg_rx->skb)
consume_skb(msg_rx->skb);
kfree(msg_rx);
}
msg_rx = list_first_entry_or_null(&psock->ingress_msg,
struct sk_msg, list);
}
return copied;
}
EXPORT_SYMBOL_GPL(__tcp_bpf_recvmsg);
int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
int nonblock, int flags, int *addr_len)
{
struct sk_psock *psock;
int copied, ret;
if (unlikely(flags & MSG_ERRQUEUE))
return inet_recv_error(sk, msg, len, addr_len);
if (!skb_queue_empty(&sk->sk_receive_queue))
return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
psock = sk_psock_get(sk);
if (unlikely(!psock))
return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
lock_sock(sk);
msg_bytes_ready:
copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags);
if (!copied) {
int data, err = 0;
long timeo;
timeo = sock_rcvtimeo(sk, nonblock);
data = tcp_bpf_wait_data(sk, psock, flags, timeo, &err);
if (data) {
if (skb_queue_empty(&sk->sk_receive_queue))
goto msg_bytes_ready;
release_sock(sk);
sk_psock_put(sk, psock);
return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
}
if (err) {
ret = err;
goto out;
}
copied = -EAGAIN;
}
ret = copied;
out:
release_sock(sk);
sk_psock_put(sk, psock);
return ret;
}
static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
struct sk_msg *msg, u32 apply_bytes, int flags)
{
bool apply = apply_bytes;
struct scatterlist *sge;
u32 size, copied = 0;
struct sk_msg *tmp;
int i, ret = 0;
tmp = kzalloc(sizeof(*tmp), __GFP_NOWARN | GFP_KERNEL);
if (unlikely(!tmp))
return -ENOMEM;
lock_sock(sk);
tmp->sg.start = msg->sg.start;
i = msg->sg.start;
do {
sge = sk_msg_elem(msg, i);
size = (apply && apply_bytes < sge->length) ?
apply_bytes : sge->length;
if (!sk_wmem_schedule(sk, size)) {
if (!copied)
ret = -ENOMEM;
break;
}
sk_mem_charge(sk, size);
sk_msg_xfer(tmp, msg, i, size);
copied += size;
if (sge->length)
get_page(sk_msg_page(tmp, i));
sk_msg_iter_var_next(i);
tmp->sg.end = i;
if (apply) {
apply_bytes -= size;
if (!apply_bytes)
break;
}
} while (i != msg->sg.end);
if (!ret) {
msg->sg.start = i;
msg->sg.size -= apply_bytes;
sk_psock_queue_msg(psock, tmp);
sk_psock_data_ready(sk, psock);
} else {
sk_msg_free(sk, tmp);
kfree(tmp);
}
release_sock(sk);
return ret;
}
static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
int flags, bool uncharge)
{
bool apply = apply_bytes;
struct scatterlist *sge;
struct page *page;
int size, ret = 0;
u32 off;
while (1) {
bool has_tx_ulp;
sge = sk_msg_elem(msg, msg->sg.start);
size = (apply && apply_bytes < sge->length) ?
apply_bytes : sge->length;
off = sge->offset;
page = sg_page(sge);
tcp_rate_check_app_limited(sk);
retry:
has_tx_ulp = tls_sw_has_ctx_tx(sk);
if (has_tx_ulp) {
flags |= MSG_SENDPAGE_NOPOLICY;
ret = kernel_sendpage_locked(sk,
page, off, size, flags);
} else {
ret = do_tcp_sendpages(sk, page, off, size, flags);
}
if (ret <= 0)
return ret;
if (apply)
apply_bytes -= ret;
msg->sg.size -= ret;
sge->offset += ret;
sge->length -= ret;
if (uncharge)
sk_mem_uncharge(sk, ret);
if (ret != size) {
size -= ret;
off += ret;
goto retry;
}
if (!sge->length) {
put_page(page);
sk_msg_iter_next(msg, start);
sg_init_table(sge, 1);
if (msg->sg.start == msg->sg.end)
break;
}
if (apply && !apply_bytes)
break;
}
return 0;
}
static int tcp_bpf_push_locked(struct sock *sk, struct sk_msg *msg,
u32 apply_bytes, int flags, bool uncharge)
{
int ret;
lock_sock(sk);
ret = tcp_bpf_push(sk, msg, apply_bytes, flags, uncharge);
release_sock(sk);
return ret;
}
int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg,
u32 bytes, int flags)
{
bool ingress = sk_msg_to_ingress(msg);
struct sk_psock *psock = sk_psock_get(sk);
int ret;
if (unlikely(!psock)) {
sk_msg_free(sk, msg);
return 0;
}
ret = ingress ? bpf_tcp_ingress(sk, psock, msg, bytes, flags) :
tcp_bpf_push_locked(sk, msg, bytes, flags, false);
sk_psock_put(sk, psock);
return ret;
}
EXPORT_SYMBOL_GPL(tcp_bpf_sendmsg_redir);
static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
struct sk_msg *msg, int *copied, int flags)
{
bool cork = false, enospc = msg->sg.start == msg->sg.end;
struct sock *sk_redir;
u32 tosend, delta = 0;
int ret;
more_data:
if (psock->eval == __SK_NONE) {
/* Track delta in msg size to add/subtract it on SK_DROP from
* returned to user copied size. This ensures user doesn't
* get a positive return code with msg_cut_data and SK_DROP
* verdict.
*/
delta = msg->sg.size;
psock->eval = sk_psock_msg_verdict(sk, psock, msg);
if (msg->sg.size < delta)
delta -= msg->sg.size;
else
delta = 0;
}
if (msg->cork_bytes &&
msg->cork_bytes > msg->sg.size && !enospc) {
psock->cork_bytes = msg->cork_bytes - msg->sg.size;
if (!psock->cork) {
psock->cork = kzalloc(sizeof(*psock->cork),
GFP_ATOMIC | __GFP_NOWARN);
if (!psock->cork)
return -ENOMEM;
}
memcpy(psock->cork, msg, sizeof(*msg));
return 0;
}
tosend = msg->sg.size;
if (psock->apply_bytes && psock->apply_bytes < tosend)
tosend = psock->apply_bytes;
switch (psock->eval) {
case __SK_PASS:
ret = tcp_bpf_push(sk, msg, tosend, flags, true);
if (unlikely(ret)) {
*copied -= sk_msg_free(sk, msg);
break;
}
sk_msg_apply_bytes(psock, tosend);
break;
case __SK_REDIRECT:
sk_redir = psock->sk_redir;
sk_msg_apply_bytes(psock, tosend);
if (psock->cork) {
cork = true;
psock->cork = NULL;
}
sk_msg_return(sk, msg, tosend);
release_sock(sk);
ret = tcp_bpf_sendmsg_redir(sk_redir, msg, tosend, flags);
lock_sock(sk);
if (unlikely(ret < 0)) {
int free = sk_msg_free_nocharge(sk, msg);
if (!cork)
*copied -= free;
}
if (cork) {
sk_msg_free(sk, msg);
kfree(msg);
msg = NULL;
ret = 0;
}
break;
case __SK_DROP:
default:
sk_msg_free_partial(sk, msg, tosend);
sk_msg_apply_bytes(psock, tosend);
*copied -= (tosend + delta);
return -EACCES;
}
if (likely(!ret)) {
if (!psock->apply_bytes) {
psock->eval = __SK_NONE;
if (psock->sk_redir) {
sock_put(psock->sk_redir);
psock->sk_redir = NULL;
}
}
if (msg &&
msg->sg.data[msg->sg.start].page_link &&
msg->sg.data[msg->sg.start].length)
goto more_data;
}
return ret;
}
static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
{
struct sk_msg tmp, *msg_tx = NULL;
int flags = msg->msg_flags | MSG_NO_SHARED_FRAGS;
int copied = 0, err = 0;
struct sk_psock *psock;
long timeo;
psock = sk_psock_get(sk);
if (unlikely(!psock))
return tcp_sendmsg(sk, msg, size);
lock_sock(sk);
timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
while (msg_data_left(msg)) {
bool enospc = false;
u32 copy, osize;
if (sk->sk_err) {
err = -sk->sk_err;
goto out_err;
}
copy = msg_data_left(msg);
if (!sk_stream_memory_free(sk))
goto wait_for_sndbuf;
if (psock->cork) {
msg_tx = psock->cork;
} else {
msg_tx = &tmp;
sk_msg_init(msg_tx);
}
osize = msg_tx->sg.size;
err = sk_msg_alloc(sk, msg_tx, msg_tx->sg.size + copy, msg_tx->sg.end - 1);
if (err) {
if (err != -ENOSPC)
goto wait_for_memory;
enospc = true;
copy = msg_tx->sg.size - osize;
}
err = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, msg_tx,
copy);
if (err < 0) {
sk_msg_trim(sk, msg_tx, osize);
goto out_err;
}
copied += copy;
if (psock->cork_bytes) {
if (size > psock->cork_bytes)
psock->cork_bytes = 0;
else
psock->cork_bytes -= size;
if (psock->cork_bytes && !enospc)
goto out_err;
/* All cork bytes are accounted, rerun the prog. */
psock->eval = __SK_NONE;
psock->cork_bytes = 0;
}
err = tcp_bpf_send_verdict(sk, psock, msg_tx, &copied, flags);
if (unlikely(err < 0))
goto out_err;
continue;
wait_for_sndbuf:
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
wait_for_memory:
err = sk_stream_wait_memory(sk, &timeo);
if (err) {
if (msg_tx && msg_tx != psock->cork)
sk_msg_free(sk, msg_tx);
goto out_err;
}
}
out_err:
if (err < 0)
err = sk_stream_error(sk, msg->msg_flags, err);
release_sock(sk);
sk_psock_put(sk, psock);
return copied ? copied : err;
}
static int tcp_bpf_sendpage(struct sock *sk, struct page *page, int offset,
size_t size, int flags)
{
struct sk_msg tmp, *msg = NULL;
int err = 0, copied = 0;
struct sk_psock *psock;
bool enospc = false;
psock = sk_psock_get(sk);
if (unlikely(!psock))
return tcp_sendpage(sk, page, offset, size, flags);
lock_sock(sk);
if (psock->cork) {
msg = psock->cork;
} else {
msg = &tmp;
sk_msg_init(msg);
}
/* Catch case where ring is full and sendpage is stalled. */
if (unlikely(sk_msg_full(msg)))
goto out_err;
sk_msg_page_add(msg, page, size, offset);
sk_mem_charge(sk, size);
copied = size;
if (sk_msg_full(msg))
enospc = true;
if (psock->cork_bytes) {
if (size > psock->cork_bytes)
psock->cork_bytes = 0;
else
psock->cork_bytes -= size;
if (psock->cork_bytes && !enospc)
goto out_err;
/* All cork bytes are accounted, rerun the prog. */
psock->eval = __SK_NONE;
psock->cork_bytes = 0;
}
err = tcp_bpf_send_verdict(sk, psock, msg, &copied, flags);
out_err:
release_sock(sk);
sk_psock_put(sk, psock);
return copied ? copied : err;
}
static void tcp_bpf_remove(struct sock *sk, struct sk_psock *psock)
{
struct sk_psock_link *link;
while ((link = sk_psock_link_pop(psock))) {
sk_psock_unlink(sk, link);
sk_psock_free_link(link);
}
}
static void tcp_bpf_unhash(struct sock *sk)
{
void (*saved_unhash)(struct sock *sk);
struct sk_psock *psock;
rcu_read_lock();
psock = sk_psock(sk);
if (unlikely(!psock)) {
rcu_read_unlock();
if (sk->sk_prot->unhash)
sk->sk_prot->unhash(sk);
return;
}
saved_unhash = psock->saved_unhash;
tcp_bpf_remove(sk, psock);
rcu_read_unlock();
saved_unhash(sk);
}
static void tcp_bpf_close(struct sock *sk, long timeout)
{
void (*saved_close)(struct sock *sk, long timeout);
struct sk_psock *psock;
lock_sock(sk);
rcu_read_lock();
psock = sk_psock(sk);
if (unlikely(!psock)) {
rcu_read_unlock();
release_sock(sk);
return sk->sk_prot->close(sk, timeout);
}
saved_close = psock->saved_close;
tcp_bpf_remove(sk, psock);
rcu_read_unlock();
release_sock(sk);
saved_close(sk, timeout);
}
enum {
TCP_BPF_IPV4,
TCP_BPF_IPV6,
TCP_BPF_NUM_PROTS,
};
enum {
TCP_BPF_BASE,
TCP_BPF_TX,
TCP_BPF_NUM_CFGS,
};
static struct proto *tcpv6_prot_saved __read_mostly;
static DEFINE_SPINLOCK(tcpv6_prot_lock);
static struct proto tcp_bpf_prots[TCP_BPF_NUM_PROTS][TCP_BPF_NUM_CFGS];
static void tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS],
struct proto *base)
{
prot[TCP_BPF_BASE] = *base;
prot[TCP_BPF_BASE].unhash = tcp_bpf_unhash;
prot[TCP_BPF_BASE].close = tcp_bpf_close;
prot[TCP_BPF_BASE].recvmsg = tcp_bpf_recvmsg;
prot[TCP_BPF_BASE].stream_memory_read = tcp_bpf_stream_read;
prot[TCP_BPF_TX] = prot[TCP_BPF_BASE];
prot[TCP_BPF_TX].sendmsg = tcp_bpf_sendmsg;
prot[TCP_BPF_TX].sendpage = tcp_bpf_sendpage;
}
static void tcp_bpf_check_v6_needs_rebuild(struct sock *sk, struct proto *ops)
{
if (sk->sk_family == AF_INET6 &&
unlikely(ops != smp_load_acquire(&tcpv6_prot_saved))) {
spin_lock_bh(&tcpv6_prot_lock);
if (likely(ops != tcpv6_prot_saved)) {
tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV6], ops);
smp_store_release(&tcpv6_prot_saved, ops);
}
spin_unlock_bh(&tcpv6_prot_lock);
}
}
static int __init tcp_bpf_v4_build_proto(void)
{
tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV4], &tcp_prot);
return 0;
}
core_initcall(tcp_bpf_v4_build_proto);
static void tcp_bpf_update_sk_prot(struct sock *sk, struct sk_psock *psock)
{
int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
int config = psock->progs.msg_parser ? TCP_BPF_TX : TCP_BPF_BASE;
sk_psock_update_proto(sk, psock, &tcp_bpf_prots[family][config]);
}
static void tcp_bpf_reinit_sk_prot(struct sock *sk, struct sk_psock *psock)
{
int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
int config = psock->progs.msg_parser ? TCP_BPF_TX : TCP_BPF_BASE;
/* Reinit occurs when program types change e.g. TCP_BPF_TX is removed
* or added requiring sk_prot hook updates. We keep original saved
* hooks in this case.
*/
sk->sk_prot = &tcp_bpf_prots[family][config];
}
static int tcp_bpf_assert_proto_ops(struct proto *ops)
{
/* In order to avoid retpoline, we make assumptions when we call
* into ops if e.g. a psock is not present. Make sure they are
* indeed valid assumptions.
*/
return ops->recvmsg == tcp_recvmsg &&
ops->sendmsg == tcp_sendmsg &&
ops->sendpage == tcp_sendpage ? 0 : -ENOTSUPP;
}
void tcp_bpf_reinit(struct sock *sk)
{
struct sk_psock *psock;
sock_owned_by_me(sk);
rcu_read_lock();
psock = sk_psock(sk);
tcp_bpf_reinit_sk_prot(sk, psock);
rcu_read_unlock();
}
int tcp_bpf_init(struct sock *sk)
{
struct proto *ops = READ_ONCE(sk->sk_prot);
struct sk_psock *psock;
sock_owned_by_me(sk);
rcu_read_lock();
psock = sk_psock(sk);
if (unlikely(!psock || psock->sk_proto ||
tcp_bpf_assert_proto_ops(ops))) {
rcu_read_unlock();
return -EINVAL;
}
tcp_bpf_check_v6_needs_rebuild(sk, ops);
tcp_bpf_update_sk_prot(sk, psock);
rcu_read_unlock();
return 0;
}