https://github.com/torvalds/linux
Tip revision: e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd authored by Linus Torvalds on 06 May 2019, 00:42:58 UTC
Linux 5.1
Linux 5.1
Tip revision: e93c9c9
skmsg.c
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2017 - 2018 Covalent IO, Inc. http://covalent.io */
#include <linux/skmsg.h>
#include <linux/skbuff.h>
#include <linux/scatterlist.h>
#include <net/sock.h>
#include <net/tcp.h>
static bool sk_msg_try_coalesce_ok(struct sk_msg *msg, int elem_first_coalesce)
{
if (msg->sg.end > msg->sg.start &&
elem_first_coalesce < msg->sg.end)
return true;
if (msg->sg.end < msg->sg.start &&
(elem_first_coalesce > msg->sg.start ||
elem_first_coalesce < msg->sg.end))
return true;
return false;
}
int sk_msg_alloc(struct sock *sk, struct sk_msg *msg, int len,
int elem_first_coalesce)
{
struct page_frag *pfrag = sk_page_frag(sk);
int ret = 0;
len -= msg->sg.size;
while (len > 0) {
struct scatterlist *sge;
u32 orig_offset;
int use, i;
if (!sk_page_frag_refill(sk, pfrag))
return -ENOMEM;
orig_offset = pfrag->offset;
use = min_t(int, len, pfrag->size - orig_offset);
if (!sk_wmem_schedule(sk, use))
return -ENOMEM;
i = msg->sg.end;
sk_msg_iter_var_prev(i);
sge = &msg->sg.data[i];
if (sk_msg_try_coalesce_ok(msg, elem_first_coalesce) &&
sg_page(sge) == pfrag->page &&
sge->offset + sge->length == orig_offset) {
sge->length += use;
} else {
if (sk_msg_full(msg)) {
ret = -ENOSPC;
break;
}
sge = &msg->sg.data[msg->sg.end];
sg_unmark_end(sge);
sg_set_page(sge, pfrag->page, use, orig_offset);
get_page(pfrag->page);
sk_msg_iter_next(msg, end);
}
sk_mem_charge(sk, use);
msg->sg.size += use;
pfrag->offset += use;
len -= use;
}
return ret;
}
EXPORT_SYMBOL_GPL(sk_msg_alloc);
int sk_msg_clone(struct sock *sk, struct sk_msg *dst, struct sk_msg *src,
u32 off, u32 len)
{
int i = src->sg.start;
struct scatterlist *sge = sk_msg_elem(src, i);
struct scatterlist *sgd = NULL;
u32 sge_len, sge_off;
while (off) {
if (sge->length > off)
break;
off -= sge->length;
sk_msg_iter_var_next(i);
if (i == src->sg.end && off)
return -ENOSPC;
sge = sk_msg_elem(src, i);
}
while (len) {
sge_len = sge->length - off;
if (sge_len > len)
sge_len = len;
if (dst->sg.end)
sgd = sk_msg_elem(dst, dst->sg.end - 1);
if (sgd &&
(sg_page(sge) == sg_page(sgd)) &&
(sg_virt(sge) + off == sg_virt(sgd) + sgd->length)) {
sgd->length += sge_len;
dst->sg.size += sge_len;
} else if (!sk_msg_full(dst)) {
sge_off = sge->offset + off;
sk_msg_page_add(dst, sg_page(sge), sge_len, sge_off);
} else {
return -ENOSPC;
}
off = 0;
len -= sge_len;
sk_mem_charge(sk, sge_len);
sk_msg_iter_var_next(i);
if (i == src->sg.end && len)
return -ENOSPC;
sge = sk_msg_elem(src, i);
}
return 0;
}
EXPORT_SYMBOL_GPL(sk_msg_clone);
void sk_msg_return_zero(struct sock *sk, struct sk_msg *msg, int bytes)
{
int i = msg->sg.start;
do {
struct scatterlist *sge = sk_msg_elem(msg, i);
if (bytes < sge->length) {
sge->length -= bytes;
sge->offset += bytes;
sk_mem_uncharge(sk, bytes);
break;
}
sk_mem_uncharge(sk, sge->length);
bytes -= sge->length;
sge->length = 0;
sge->offset = 0;
sk_msg_iter_var_next(i);
} while (bytes && i != msg->sg.end);
msg->sg.start = i;
}
EXPORT_SYMBOL_GPL(sk_msg_return_zero);
void sk_msg_return(struct sock *sk, struct sk_msg *msg, int bytes)
{
int i = msg->sg.start;
do {
struct scatterlist *sge = &msg->sg.data[i];
int uncharge = (bytes < sge->length) ? bytes : sge->length;
sk_mem_uncharge(sk, uncharge);
bytes -= uncharge;
sk_msg_iter_var_next(i);
} while (i != msg->sg.end);
}
EXPORT_SYMBOL_GPL(sk_msg_return);
static int sk_msg_free_elem(struct sock *sk, struct sk_msg *msg, u32 i,
bool charge)
{
struct scatterlist *sge = sk_msg_elem(msg, i);
u32 len = sge->length;
if (charge)
sk_mem_uncharge(sk, len);
if (!msg->skb)
put_page(sg_page(sge));
memset(sge, 0, sizeof(*sge));
return len;
}
static int __sk_msg_free(struct sock *sk, struct sk_msg *msg, u32 i,
bool charge)
{
struct scatterlist *sge = sk_msg_elem(msg, i);
int freed = 0;
while (msg->sg.size) {
msg->sg.size -= sge->length;
freed += sk_msg_free_elem(sk, msg, i, charge);
sk_msg_iter_var_next(i);
sk_msg_check_to_free(msg, i, msg->sg.size);
sge = sk_msg_elem(msg, i);
}
if (msg->skb)
consume_skb(msg->skb);
sk_msg_init(msg);
return freed;
}
int sk_msg_free_nocharge(struct sock *sk, struct sk_msg *msg)
{
return __sk_msg_free(sk, msg, msg->sg.start, false);
}
EXPORT_SYMBOL_GPL(sk_msg_free_nocharge);
int sk_msg_free(struct sock *sk, struct sk_msg *msg)
{
return __sk_msg_free(sk, msg, msg->sg.start, true);
}
EXPORT_SYMBOL_GPL(sk_msg_free);
static void __sk_msg_free_partial(struct sock *sk, struct sk_msg *msg,
u32 bytes, bool charge)
{
struct scatterlist *sge;
u32 i = msg->sg.start;
while (bytes) {
sge = sk_msg_elem(msg, i);
if (!sge->length)
break;
if (bytes < sge->length) {
if (charge)
sk_mem_uncharge(sk, bytes);
sge->length -= bytes;
sge->offset += bytes;
msg->sg.size -= bytes;
break;
}
msg->sg.size -= sge->length;
bytes -= sge->length;
sk_msg_free_elem(sk, msg, i, charge);
sk_msg_iter_var_next(i);
sk_msg_check_to_free(msg, i, bytes);
}
msg->sg.start = i;
}
void sk_msg_free_partial(struct sock *sk, struct sk_msg *msg, u32 bytes)
{
__sk_msg_free_partial(sk, msg, bytes, true);
}
EXPORT_SYMBOL_GPL(sk_msg_free_partial);
void sk_msg_free_partial_nocharge(struct sock *sk, struct sk_msg *msg,
u32 bytes)
{
__sk_msg_free_partial(sk, msg, bytes, false);
}
void sk_msg_trim(struct sock *sk, struct sk_msg *msg, int len)
{
int trim = msg->sg.size - len;
u32 i = msg->sg.end;
if (trim <= 0) {
WARN_ON(trim < 0);
return;
}
sk_msg_iter_var_prev(i);
msg->sg.size = len;
while (msg->sg.data[i].length &&
trim >= msg->sg.data[i].length) {
trim -= msg->sg.data[i].length;
sk_msg_free_elem(sk, msg, i, true);
sk_msg_iter_var_prev(i);
if (!trim)
goto out;
}
msg->sg.data[i].length -= trim;
sk_mem_uncharge(sk, trim);
out:
/* If we trim data before curr pointer update copybreak and current
* so that any future copy operations start at new copy location.
* However trimed data that has not yet been used in a copy op
* does not require an update.
*/
if (msg->sg.curr >= i) {
msg->sg.curr = i;
msg->sg.copybreak = msg->sg.data[i].length;
}
sk_msg_iter_var_next(i);
msg->sg.end = i;
}
EXPORT_SYMBOL_GPL(sk_msg_trim);
int sk_msg_zerocopy_from_iter(struct sock *sk, struct iov_iter *from,
struct sk_msg *msg, u32 bytes)
{
int i, maxpages, ret = 0, num_elems = sk_msg_elem_used(msg);
const int to_max_pages = MAX_MSG_FRAGS;
struct page *pages[MAX_MSG_FRAGS];
ssize_t orig, copied, use, offset;
orig = msg->sg.size;
while (bytes > 0) {
i = 0;
maxpages = to_max_pages - num_elems;
if (maxpages == 0) {
ret = -EFAULT;
goto out;
}
copied = iov_iter_get_pages(from, pages, bytes, maxpages,
&offset);
if (copied <= 0) {
ret = -EFAULT;
goto out;
}
iov_iter_advance(from, copied);
bytes -= copied;
msg->sg.size += copied;
while (copied) {
use = min_t(int, copied, PAGE_SIZE - offset);
sg_set_page(&msg->sg.data[msg->sg.end],
pages[i], use, offset);
sg_unmark_end(&msg->sg.data[msg->sg.end]);
sk_mem_charge(sk, use);
offset = 0;
copied -= use;
sk_msg_iter_next(msg, end);
num_elems++;
i++;
}
/* When zerocopy is mixed with sk_msg_*copy* operations we
* may have a copybreak set in this case clear and prefer
* zerocopy remainder when possible.
*/
msg->sg.copybreak = 0;
msg->sg.curr = msg->sg.end;
}
out:
/* Revert iov_iter updates, msg will need to use 'trim' later if it
* also needs to be cleared.
*/
if (ret)
iov_iter_revert(from, msg->sg.size - orig);
return ret;
}
EXPORT_SYMBOL_GPL(sk_msg_zerocopy_from_iter);
int sk_msg_memcopy_from_iter(struct sock *sk, struct iov_iter *from,
struct sk_msg *msg, u32 bytes)
{
int ret = -ENOSPC, i = msg->sg.curr;
struct scatterlist *sge;
u32 copy, buf_size;
void *to;
do {
sge = sk_msg_elem(msg, i);
/* This is possible if a trim operation shrunk the buffer */
if (msg->sg.copybreak >= sge->length) {
msg->sg.copybreak = 0;
sk_msg_iter_var_next(i);
if (i == msg->sg.end)
break;
sge = sk_msg_elem(msg, i);
}
buf_size = sge->length - msg->sg.copybreak;
copy = (buf_size > bytes) ? bytes : buf_size;
to = sg_virt(sge) + msg->sg.copybreak;
msg->sg.copybreak += copy;
if (sk->sk_route_caps & NETIF_F_NOCACHE_COPY)
ret = copy_from_iter_nocache(to, copy, from);
else
ret = copy_from_iter(to, copy, from);
if (ret != copy) {
ret = -EFAULT;
goto out;
}
bytes -= copy;
if (!bytes)
break;
msg->sg.copybreak = 0;
sk_msg_iter_var_next(i);
} while (i != msg->sg.end);
out:
msg->sg.curr = i;
return ret;
}
EXPORT_SYMBOL_GPL(sk_msg_memcopy_from_iter);
static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb)
{
struct sock *sk = psock->sk;
int copied = 0, num_sge;
struct sk_msg *msg;
msg = kzalloc(sizeof(*msg), __GFP_NOWARN | GFP_ATOMIC);
if (unlikely(!msg))
return -EAGAIN;
if (!sk_rmem_schedule(sk, skb, skb->len)) {
kfree(msg);
return -EAGAIN;
}
sk_msg_init(msg);
num_sge = skb_to_sgvec(skb, msg->sg.data, 0, skb->len);
if (unlikely(num_sge < 0)) {
kfree(msg);
return num_sge;
}
sk_mem_charge(sk, skb->len);
copied = skb->len;
msg->sg.start = 0;
msg->sg.end = num_sge == MAX_MSG_FRAGS ? 0 : num_sge;
msg->skb = skb;
sk_psock_queue_msg(psock, msg);
sk_psock_data_ready(sk, psock);
return copied;
}
static int sk_psock_handle_skb(struct sk_psock *psock, struct sk_buff *skb,
u32 off, u32 len, bool ingress)
{
if (ingress)
return sk_psock_skb_ingress(psock, skb);
else
return skb_send_sock_locked(psock->sk, skb, off, len);
}
static void sk_psock_backlog(struct work_struct *work)
{
struct sk_psock *psock = container_of(work, struct sk_psock, work);
struct sk_psock_work_state *state = &psock->work_state;
struct sk_buff *skb;
bool ingress;
u32 len, off;
int ret;
/* Lock sock to avoid losing sk_socket during loop. */
lock_sock(psock->sk);
if (state->skb) {
skb = state->skb;
len = state->len;
off = state->off;
state->skb = NULL;
goto start;
}
while ((skb = skb_dequeue(&psock->ingress_skb))) {
len = skb->len;
off = 0;
start:
ingress = tcp_skb_bpf_ingress(skb);
do {
ret = -EIO;
if (likely(psock->sk->sk_socket))
ret = sk_psock_handle_skb(psock, skb, off,
len, ingress);
if (ret <= 0) {
if (ret == -EAGAIN) {
state->skb = skb;
state->len = len;
state->off = off;
goto end;
}
/* Hard errors break pipe and stop xmit. */
sk_psock_report_error(psock, ret ? -ret : EPIPE);
sk_psock_clear_state(psock, SK_PSOCK_TX_ENABLED);
kfree_skb(skb);
goto end;
}
off += ret;
len -= ret;
} while (len);
if (!ingress)
kfree_skb(skb);
}
end:
release_sock(psock->sk);
}
struct sk_psock *sk_psock_init(struct sock *sk, int node)
{
struct sk_psock *psock = kzalloc_node(sizeof(*psock),
GFP_ATOMIC | __GFP_NOWARN,
node);
if (!psock)
return NULL;
psock->sk = sk;
psock->eval = __SK_NONE;
INIT_LIST_HEAD(&psock->link);
spin_lock_init(&psock->link_lock);
INIT_WORK(&psock->work, sk_psock_backlog);
INIT_LIST_HEAD(&psock->ingress_msg);
skb_queue_head_init(&psock->ingress_skb);
sk_psock_set_state(psock, SK_PSOCK_TX_ENABLED);
refcount_set(&psock->refcnt, 1);
rcu_assign_sk_user_data(sk, psock);
sock_hold(sk);
return psock;
}
EXPORT_SYMBOL_GPL(sk_psock_init);
struct sk_psock_link *sk_psock_link_pop(struct sk_psock *psock)
{
struct sk_psock_link *link;
spin_lock_bh(&psock->link_lock);
link = list_first_entry_or_null(&psock->link, struct sk_psock_link,
list);
if (link)
list_del(&link->list);
spin_unlock_bh(&psock->link_lock);
return link;
}
void __sk_psock_purge_ingress_msg(struct sk_psock *psock)
{
struct sk_msg *msg, *tmp;
list_for_each_entry_safe(msg, tmp, &psock->ingress_msg, list) {
list_del(&msg->list);
sk_msg_free(psock->sk, msg);
kfree(msg);
}
}
static void sk_psock_zap_ingress(struct sk_psock *psock)
{
__skb_queue_purge(&psock->ingress_skb);
__sk_psock_purge_ingress_msg(psock);
}
static void sk_psock_link_destroy(struct sk_psock *psock)
{
struct sk_psock_link *link, *tmp;
list_for_each_entry_safe(link, tmp, &psock->link, list) {
list_del(&link->list);
sk_psock_free_link(link);
}
}
static void sk_psock_destroy_deferred(struct work_struct *gc)
{
struct sk_psock *psock = container_of(gc, struct sk_psock, gc);
/* No sk_callback_lock since already detached. */
strp_stop(&psock->parser.strp);
strp_done(&psock->parser.strp);
cancel_work_sync(&psock->work);
psock_progs_drop(&psock->progs);
sk_psock_link_destroy(psock);
sk_psock_cork_free(psock);
sk_psock_zap_ingress(psock);
if (psock->sk_redir)
sock_put(psock->sk_redir);
sock_put(psock->sk);
kfree(psock);
}
void sk_psock_destroy(struct rcu_head *rcu)
{
struct sk_psock *psock = container_of(rcu, struct sk_psock, rcu);
INIT_WORK(&psock->gc, sk_psock_destroy_deferred);
schedule_work(&psock->gc);
}
EXPORT_SYMBOL_GPL(sk_psock_destroy);
void sk_psock_drop(struct sock *sk, struct sk_psock *psock)
{
rcu_assign_sk_user_data(sk, NULL);
sk_psock_cork_free(psock);
sk_psock_zap_ingress(psock);
sk_psock_restore_proto(sk, psock);
write_lock_bh(&sk->sk_callback_lock);
if (psock->progs.skb_parser)
sk_psock_stop_strp(sk, psock);
write_unlock_bh(&sk->sk_callback_lock);
sk_psock_clear_state(psock, SK_PSOCK_TX_ENABLED);
call_rcu(&psock->rcu, sk_psock_destroy);
}
EXPORT_SYMBOL_GPL(sk_psock_drop);
static int sk_psock_map_verd(int verdict, bool redir)
{
switch (verdict) {
case SK_PASS:
return redir ? __SK_REDIRECT : __SK_PASS;
case SK_DROP:
default:
break;
}
return __SK_DROP;
}
int sk_psock_msg_verdict(struct sock *sk, struct sk_psock *psock,
struct sk_msg *msg)
{
struct bpf_prog *prog;
int ret;
preempt_disable();
rcu_read_lock();
prog = READ_ONCE(psock->progs.msg_parser);
if (unlikely(!prog)) {
ret = __SK_PASS;
goto out;
}
sk_msg_compute_data_pointers(msg);
msg->sk = sk;
ret = BPF_PROG_RUN(prog, msg);
ret = sk_psock_map_verd(ret, msg->sk_redir);
psock->apply_bytes = msg->apply_bytes;
if (ret == __SK_REDIRECT) {
if (psock->sk_redir)
sock_put(psock->sk_redir);
psock->sk_redir = msg->sk_redir;
if (!psock->sk_redir) {
ret = __SK_DROP;
goto out;
}
sock_hold(psock->sk_redir);
}
out:
rcu_read_unlock();
preempt_enable();
return ret;
}
EXPORT_SYMBOL_GPL(sk_psock_msg_verdict);
static int sk_psock_bpf_run(struct sk_psock *psock, struct bpf_prog *prog,
struct sk_buff *skb)
{
int ret;
skb->sk = psock->sk;
bpf_compute_data_end_sk_skb(skb);
preempt_disable();
ret = BPF_PROG_RUN(prog, skb);
preempt_enable();
/* strparser clones the skb before handing it to a upper layer,
* meaning skb_orphan has been called. We NULL sk on the way out
* to ensure we don't trigger a BUG_ON() in skb/sk operations
* later and because we are not charging the memory of this skb
* to any socket yet.
*/
skb->sk = NULL;
return ret;
}
static struct sk_psock *sk_psock_from_strp(struct strparser *strp)
{
struct sk_psock_parser *parser;
parser = container_of(strp, struct sk_psock_parser, strp);
return container_of(parser, struct sk_psock, parser);
}
static void sk_psock_verdict_apply(struct sk_psock *psock,
struct sk_buff *skb, int verdict)
{
struct sk_psock *psock_other;
struct sock *sk_other;
bool ingress;
switch (verdict) {
case __SK_PASS:
sk_other = psock->sk;
if (sock_flag(sk_other, SOCK_DEAD) ||
!sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) {
goto out_free;
}
if (atomic_read(&sk_other->sk_rmem_alloc) <=
sk_other->sk_rcvbuf) {
struct tcp_skb_cb *tcp = TCP_SKB_CB(skb);
tcp->bpf.flags |= BPF_F_INGRESS;
skb_queue_tail(&psock->ingress_skb, skb);
schedule_work(&psock->work);
break;
}
goto out_free;
case __SK_REDIRECT:
sk_other = tcp_skb_bpf_redirect_fetch(skb);
if (unlikely(!sk_other))
goto out_free;
psock_other = sk_psock(sk_other);
if (!psock_other || sock_flag(sk_other, SOCK_DEAD) ||
!sk_psock_test_state(psock_other, SK_PSOCK_TX_ENABLED))
goto out_free;
ingress = tcp_skb_bpf_ingress(skb);
if ((!ingress && sock_writeable(sk_other)) ||
(ingress &&
atomic_read(&sk_other->sk_rmem_alloc) <=
sk_other->sk_rcvbuf)) {
if (!ingress)
skb_set_owner_w(skb, sk_other);
skb_queue_tail(&psock_other->ingress_skb, skb);
schedule_work(&psock_other->work);
break;
}
/* fall-through */
case __SK_DROP:
/* fall-through */
default:
out_free:
kfree_skb(skb);
}
}
static void sk_psock_strp_read(struct strparser *strp, struct sk_buff *skb)
{
struct sk_psock *psock = sk_psock_from_strp(strp);
struct bpf_prog *prog;
int ret = __SK_DROP;
rcu_read_lock();
prog = READ_ONCE(psock->progs.skb_verdict);
if (likely(prog)) {
skb_orphan(skb);
tcp_skb_bpf_redirect_clear(skb);
ret = sk_psock_bpf_run(psock, prog, skb);
ret = sk_psock_map_verd(ret, tcp_skb_bpf_redirect_fetch(skb));
}
rcu_read_unlock();
sk_psock_verdict_apply(psock, skb, ret);
}
static int sk_psock_strp_read_done(struct strparser *strp, int err)
{
return err;
}
static int sk_psock_strp_parse(struct strparser *strp, struct sk_buff *skb)
{
struct sk_psock *psock = sk_psock_from_strp(strp);
struct bpf_prog *prog;
int ret = skb->len;
rcu_read_lock();
prog = READ_ONCE(psock->progs.skb_parser);
if (likely(prog))
ret = sk_psock_bpf_run(psock, prog, skb);
rcu_read_unlock();
return ret;
}
/* Called with socket lock held. */
static void sk_psock_strp_data_ready(struct sock *sk)
{
struct sk_psock *psock;
rcu_read_lock();
psock = sk_psock(sk);
if (likely(psock)) {
write_lock_bh(&sk->sk_callback_lock);
strp_data_ready(&psock->parser.strp);
write_unlock_bh(&sk->sk_callback_lock);
}
rcu_read_unlock();
}
static void sk_psock_write_space(struct sock *sk)
{
struct sk_psock *psock;
void (*write_space)(struct sock *sk);
rcu_read_lock();
psock = sk_psock(sk);
if (likely(psock && sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)))
schedule_work(&psock->work);
write_space = psock->saved_write_space;
rcu_read_unlock();
write_space(sk);
}
int sk_psock_init_strp(struct sock *sk, struct sk_psock *psock)
{
static const struct strp_callbacks cb = {
.rcv_msg = sk_psock_strp_read,
.read_sock_done = sk_psock_strp_read_done,
.parse_msg = sk_psock_strp_parse,
};
psock->parser.enabled = false;
return strp_init(&psock->parser.strp, sk, &cb);
}
void sk_psock_start_strp(struct sock *sk, struct sk_psock *psock)
{
struct sk_psock_parser *parser = &psock->parser;
if (parser->enabled)
return;
parser->saved_data_ready = sk->sk_data_ready;
sk->sk_data_ready = sk_psock_strp_data_ready;
sk->sk_write_space = sk_psock_write_space;
parser->enabled = true;
}
void sk_psock_stop_strp(struct sock *sk, struct sk_psock *psock)
{
struct sk_psock_parser *parser = &psock->parser;
if (!parser->enabled)
return;
sk->sk_data_ready = parser->saved_data_ready;
parser->saved_data_ready = NULL;
strp_stop(&parser->strp);
parser->enabled = false;
}