// 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 <linux/util_macros.h>
#include <net/inet_common.h>
#include <net/tls.h>
void tcp_eat_skb(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tcp;
int copied;
if (!skb || !skb->len || !sk_is_tcp(sk))
return;
if (skb_bpf_strparser(skb))
return;
tcp = tcp_sk(sk);
copied = tcp->copied_seq + skb->len;
WRITE_ONCE(tcp->copied_seq, copied);
tcp_rcv_space_adjust(sk);
__tcp_cleanup_rbuf(sk, skb->len);
}
static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
struct sk_msg *msg, u32 apply_bytes)
{
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) {
if (sge->length)
sk_msg_iter_var_prev(i);
break;
}
}
} while (i != msg->sg.end);
if (!ret) {
msg->sg.start = i;
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)
{
struct msghdr msghdr = {};
bool apply = apply_bytes;
struct scatterlist *sge;
struct page *page;
int size, ret = 0;
u32 off;
while (1) {
struct bio_vec bvec;
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:
msghdr.msg_flags = flags | MSG_SPLICE_PAGES;
has_tx_ulp = tls_sw_has_ctx_tx(sk);
if (has_tx_ulp)
msghdr.msg_flags |= MSG_SENDPAGE_NOPOLICY;
if (size < sge->length && msg->sg.start != msg->sg.end)
msghdr.msg_flags |= MSG_MORE;
bvec_set_page(&bvec, page, size, off);
iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, size);
ret = tcp_sendmsg_locked(sk, &msghdr, size);
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, bool ingress,
struct sk_msg *msg, u32 bytes, int flags)
{
struct sk_psock *psock = sk_psock_get(sk);
int ret;
if (unlikely(!psock))
return -EPIPE;
ret = ingress ? bpf_tcp_ingress(sk, psock, msg, bytes) :
tcp_bpf_push_locked(sk, msg, bytes, flags, false);
sk_psock_put(sk, psock);
return ret;
}
EXPORT_SYMBOL_GPL(tcp_bpf_sendmsg_redir);
#ifdef CONFIG_BPF_SYSCALL
static int tcp_msg_wait_data(struct sock *sk, struct sk_psock *psock,
long timeo)
{
DEFINE_WAIT_FUNC(wait, woken_wake_function);
int ret = 0;
if (sk->sk_shutdown & RCV_SHUTDOWN)
return 1;
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_lockless(&sk->sk_receive_queue), &wait);
sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
remove_wait_queue(sk_sleep(sk), &wait);
return ret;
}
static bool is_next_msg_fin(struct sk_psock *psock)
{
struct scatterlist *sge;
struct sk_msg *msg_rx;
int i;
msg_rx = sk_psock_peek_msg(psock);
i = msg_rx->sg.start;
sge = sk_msg_elem(msg_rx, i);
if (!sge->length) {
struct sk_buff *skb = msg_rx->skb;
if (skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
return true;
}
return false;
}
static int tcp_bpf_recvmsg_parser(struct sock *sk,
struct msghdr *msg,
size_t len,
int flags,
int *addr_len)
{
struct tcp_sock *tcp = tcp_sk(sk);
int peek = flags & MSG_PEEK;
u32 seq = tcp->copied_seq;
struct sk_psock *psock;
int copied = 0;
if (unlikely(flags & MSG_ERRQUEUE))
return inet_recv_error(sk, msg, len, addr_len);
if (!len)
return 0;
psock = sk_psock_get(sk);
if (unlikely(!psock))
return tcp_recvmsg(sk, msg, len, flags, addr_len);
lock_sock(sk);
/* We may have received data on the sk_receive_queue pre-accept and
* then we can not use read_skb in this context because we haven't
* assigned a sk_socket yet so have no link to the ops. The work-around
* is to check the sk_receive_queue and in these cases read skbs off
* queue again. The read_skb hook is not running at this point because
* of lock_sock so we avoid having multiple runners in read_skb.
*/
if (unlikely(!skb_queue_empty(&sk->sk_receive_queue))) {
tcp_data_ready(sk);
/* This handles the ENOMEM errors if we both receive data
* pre accept and are already under memory pressure. At least
* let user know to retry.
*/
if (unlikely(!skb_queue_empty(&sk->sk_receive_queue))) {
copied = -EAGAIN;
goto out;
}
}
msg_bytes_ready:
copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
/* The typical case for EFAULT is the socket was gracefully
* shutdown with a FIN pkt. So check here the other case is
* some error on copy_page_to_iter which would be unexpected.
* On fin return correct return code to zero.
*/
if (copied == -EFAULT) {
bool is_fin = is_next_msg_fin(psock);
if (is_fin) {
copied = 0;
seq++;
goto out;
}
}
seq += copied;
if (!copied) {
long timeo;
int data;
if (sock_flag(sk, SOCK_DONE))
goto out;
if (sk->sk_err) {
copied = sock_error(sk);
goto out;
}
if (sk->sk_shutdown & RCV_SHUTDOWN)
goto out;
if (sk->sk_state == TCP_CLOSE) {
copied = -ENOTCONN;
goto out;
}
timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
if (!timeo) {
copied = -EAGAIN;
goto out;
}
if (signal_pending(current)) {
copied = sock_intr_errno(timeo);
goto out;
}
data = tcp_msg_wait_data(sk, psock, timeo);
if (data < 0) {
copied = data;
goto unlock;
}
if (data && !sk_psock_queue_empty(psock))
goto msg_bytes_ready;
copied = -EAGAIN;
}
out:
if (!peek)
WRITE_ONCE(tcp->copied_seq, seq);
tcp_rcv_space_adjust(sk);
if (copied > 0)
__tcp_cleanup_rbuf(sk, copied);
unlock:
release_sock(sk);
sk_psock_put(sk, psock);
return copied;
}
static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
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 (!len)
return 0;
psock = sk_psock_get(sk);
if (unlikely(!psock))
return tcp_recvmsg(sk, msg, len, flags, addr_len);
if (!skb_queue_empty(&sk->sk_receive_queue) &&
sk_psock_queue_empty(psock)) {
sk_psock_put(sk, psock);
return tcp_recvmsg(sk, msg, len, flags, addr_len);
}
lock_sock(sk);
msg_bytes_ready:
copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
if (!copied) {
long timeo;
int data;
timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
data = tcp_msg_wait_data(sk, psock, timeo);
if (data < 0) {
ret = data;
goto unlock;
}
if (data) {
if (!sk_psock_queue_empty(psock))
goto msg_bytes_ready;
release_sock(sk);
sk_psock_put(sk, psock);
return tcp_recvmsg(sk, msg, len, flags, addr_len);
}
copied = -EAGAIN;
}
ret = copied;
unlock:
release_sock(sk);
sk_psock_put(sk, psock);
return ret;
}
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 = sk_msg_full(msg), redir_ingress;
struct sock *sk_redir;
u32 tosend, origsize, sent, delta = 0;
u32 eval;
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);
delta -= msg->sg.size;
}
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;
eval = __SK_NONE;
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:
redir_ingress = psock->redir_ingress;
sk_redir = psock->sk_redir;
sk_msg_apply_bytes(psock, tosend);
if (!psock->apply_bytes) {
/* Clean up before releasing the sock lock. */
eval = psock->eval;
psock->eval = __SK_NONE;
psock->sk_redir = NULL;
}
if (psock->cork) {
cork = true;
psock->cork = NULL;
}
sk_msg_return(sk, msg, tosend);
release_sock(sk);
origsize = msg->sg.size;
ret = tcp_bpf_sendmsg_redir(sk_redir, redir_ingress,
msg, tosend, flags);
sent = origsize - msg->sg.size;
if (eval == __SK_REDIRECT)
sock_put(sk_redir);
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) {
if (eval == __SK_REDIRECT)
sk_mem_charge(sk, tosend - sent);
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 copied = 0, err = 0;
struct sk_psock *psock;
long timeo;
int flags;
/* Don't let internal flags through */
flags = (msg->msg_flags & ~MSG_SENDPAGE_DECRYPTED);
flags |= MSG_NO_SHARED_FRAGS;
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 > 0 ? copied : err;
}
enum {
TCP_BPF_IPV4,
TCP_BPF_IPV6,
TCP_BPF_NUM_PROTS,
};
enum {
TCP_BPF_BASE,
TCP_BPF_TX,
TCP_BPF_RX,
TCP_BPF_TXRX,
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].destroy = sock_map_destroy;
prot[TCP_BPF_BASE].close = sock_map_close;
prot[TCP_BPF_BASE].recvmsg = tcp_bpf_recvmsg;
prot[TCP_BPF_BASE].sock_is_readable = sk_msg_is_readable;
prot[TCP_BPF_TX] = prot[TCP_BPF_BASE];
prot[TCP_BPF_TX].sendmsg = tcp_bpf_sendmsg;
prot[TCP_BPF_RX] = prot[TCP_BPF_BASE];
prot[TCP_BPF_RX].recvmsg = tcp_bpf_recvmsg_parser;
prot[TCP_BPF_TXRX] = prot[TCP_BPF_TX];
prot[TCP_BPF_TXRX].recvmsg = tcp_bpf_recvmsg_parser;
}
static void tcp_bpf_check_v6_needs_rebuild(struct proto *ops)
{
if (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;
}
late_initcall(tcp_bpf_v4_build_proto);
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 ? 0 : -ENOTSUPP;
}
int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
{
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;
if (psock->progs.stream_verdict || psock->progs.skb_verdict) {
config = (config == TCP_BPF_TX) ? TCP_BPF_TXRX : TCP_BPF_RX;
}
if (restore) {
if (inet_csk_has_ulp(sk)) {
/* TLS does not have an unhash proto in SW cases,
* but we need to ensure we stop using the sock_map
* unhash routine because the associated psock is being
* removed. So use the original unhash handler.
*/
WRITE_ONCE(sk->sk_prot->unhash, psock->saved_unhash);
tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
} else {
sk->sk_write_space = psock->saved_write_space;
/* Pairs with lockless read in sk_clone_lock() */
sock_replace_proto(sk, psock->sk_proto);
}
return 0;
}
if (sk->sk_family == AF_INET6) {
if (tcp_bpf_assert_proto_ops(psock->sk_proto))
return -EINVAL;
tcp_bpf_check_v6_needs_rebuild(psock->sk_proto);
}
/* Pairs with lockless read in sk_clone_lock() */
sock_replace_proto(sk, &tcp_bpf_prots[family][config]);
return 0;
}
EXPORT_SYMBOL_GPL(tcp_bpf_update_proto);
/* If a child got cloned from a listening socket that had tcp_bpf
* protocol callbacks installed, we need to restore the callbacks to
* the default ones because the child does not inherit the psock state
* that tcp_bpf callbacks expect.
*/
void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
{
struct proto *prot = newsk->sk_prot;
if (is_insidevar(prot, tcp_bpf_prots))
newsk->sk_prot = sk->sk_prot_creator;
}
#endif /* CONFIG_BPF_SYSCALL */
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