linux/net/strparser/strparser.c
Tom Herbert 96a5908347 kcm: Remove TCP specific references from kcm and strparser
kcm and strparser need to work with any type of stream socket not just
TCP. Eliminate references to TCP and call generic proto_ops functions of
read_sock and peek_len. Also in strp_init check if the socket support
the proto_ops read_sock and peek_len.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-28 23:32:41 -04:00

511 lines
12 KiB
C

/*
* Stream Parser
*
* Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*/
#include <linux/bpf.h>
#include <linux/errno.h>
#include <linux/errqueue.h>
#include <linux/file.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/poll.h>
#include <linux/rculist.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/uaccess.h>
#include <linux/workqueue.h>
#include <net/strparser.h>
#include <net/netns/generic.h>
#include <net/sock.h>
static struct workqueue_struct *strp_wq;
struct _strp_rx_msg {
/* Internal cb structure. struct strp_rx_msg must be first for passing
* to upper layer.
*/
struct strp_rx_msg strp;
int accum_len;
int early_eaten;
};
static inline struct _strp_rx_msg *_strp_rx_msg(struct sk_buff *skb)
{
return (struct _strp_rx_msg *)((void *)skb->cb +
offsetof(struct qdisc_skb_cb, data));
}
/* Lower lock held */
static void strp_abort_rx_strp(struct strparser *strp, int err)
{
struct sock *csk = strp->sk;
/* Unrecoverable error in receive */
del_timer(&strp->rx_msg_timer);
if (strp->rx_stopped)
return;
strp->rx_stopped = 1;
/* Report an error on the lower socket */
csk->sk_err = err;
csk->sk_error_report(csk);
}
static void strp_start_rx_timer(struct strparser *strp)
{
if (strp->sk->sk_rcvtimeo)
mod_timer(&strp->rx_msg_timer, strp->sk->sk_rcvtimeo);
}
/* Lower lock held */
static void strp_parser_err(struct strparser *strp, int err,
read_descriptor_t *desc)
{
desc->error = err;
kfree_skb(strp->rx_skb_head);
strp->rx_skb_head = NULL;
strp->cb.abort_parser(strp, err);
}
static inline int strp_peek_len(struct strparser *strp)
{
struct socket *sock = strp->sk->sk_socket;
return sock->ops->peek_len(sock);
}
/* Lower socket lock held */
static int strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
unsigned int orig_offset, size_t orig_len)
{
struct strparser *strp = (struct strparser *)desc->arg.data;
struct _strp_rx_msg *rxm;
struct sk_buff *head, *skb;
size_t eaten = 0, cand_len;
ssize_t extra;
int err;
bool cloned_orig = false;
if (strp->rx_paused)
return 0;
head = strp->rx_skb_head;
if (head) {
/* Message already in progress */
rxm = _strp_rx_msg(head);
if (unlikely(rxm->early_eaten)) {
/* Already some number of bytes on the receive sock
* data saved in rx_skb_head, just indicate they
* are consumed.
*/
eaten = orig_len <= rxm->early_eaten ?
orig_len : rxm->early_eaten;
rxm->early_eaten -= eaten;
return eaten;
}
if (unlikely(orig_offset)) {
/* Getting data with a non-zero offset when a message is
* in progress is not expected. If it does happen, we
* need to clone and pull since we can't deal with
* offsets in the skbs for a message expect in the head.
*/
orig_skb = skb_clone(orig_skb, GFP_ATOMIC);
if (!orig_skb) {
STRP_STATS_INCR(strp->stats.rx_mem_fail);
desc->error = -ENOMEM;
return 0;
}
if (!pskb_pull(orig_skb, orig_offset)) {
STRP_STATS_INCR(strp->stats.rx_mem_fail);
kfree_skb(orig_skb);
desc->error = -ENOMEM;
return 0;
}
cloned_orig = true;
orig_offset = 0;
}
if (!strp->rx_skb_nextp) {
/* We are going to append to the frags_list of head.
* Need to unshare the frag_list.
*/
err = skb_unclone(head, GFP_ATOMIC);
if (err) {
STRP_STATS_INCR(strp->stats.rx_mem_fail);
desc->error = err;
return 0;
}
if (unlikely(skb_shinfo(head)->frag_list)) {
/* We can't append to an sk_buff that already
* has a frag_list. We create a new head, point
* the frag_list of that to the old head, and
* then are able to use the old head->next for
* appending to the message.
*/
if (WARN_ON(head->next)) {
desc->error = -EINVAL;
return 0;
}
skb = alloc_skb(0, GFP_ATOMIC);
if (!skb) {
STRP_STATS_INCR(strp->stats.rx_mem_fail);
desc->error = -ENOMEM;
return 0;
}
skb->len = head->len;
skb->data_len = head->len;
skb->truesize = head->truesize;
*_strp_rx_msg(skb) = *_strp_rx_msg(head);
strp->rx_skb_nextp = &head->next;
skb_shinfo(skb)->frag_list = head;
strp->rx_skb_head = skb;
head = skb;
} else {
strp->rx_skb_nextp =
&skb_shinfo(head)->frag_list;
}
}
}
while (eaten < orig_len) {
/* Always clone since we will consume something */
skb = skb_clone(orig_skb, GFP_ATOMIC);
if (!skb) {
STRP_STATS_INCR(strp->stats.rx_mem_fail);
desc->error = -ENOMEM;
break;
}
cand_len = orig_len - eaten;
head = strp->rx_skb_head;
if (!head) {
head = skb;
strp->rx_skb_head = head;
/* Will set rx_skb_nextp on next packet if needed */
strp->rx_skb_nextp = NULL;
rxm = _strp_rx_msg(head);
memset(rxm, 0, sizeof(*rxm));
rxm->strp.offset = orig_offset + eaten;
} else {
/* Unclone since we may be appending to an skb that we
* already share a frag_list with.
*/
err = skb_unclone(skb, GFP_ATOMIC);
if (err) {
STRP_STATS_INCR(strp->stats.rx_mem_fail);
desc->error = err;
break;
}
rxm = _strp_rx_msg(head);
*strp->rx_skb_nextp = skb;
strp->rx_skb_nextp = &skb->next;
head->data_len += skb->len;
head->len += skb->len;
head->truesize += skb->truesize;
}
if (!rxm->strp.full_len) {
ssize_t len;
len = (*strp->cb.parse_msg)(strp, head);
if (!len) {
/* Need more header to determine length */
if (!rxm->accum_len) {
/* Start RX timer for new message */
strp_start_rx_timer(strp);
}
rxm->accum_len += cand_len;
eaten += cand_len;
STRP_STATS_INCR(strp->stats.rx_need_more_hdr);
WARN_ON(eaten != orig_len);
break;
} else if (len < 0) {
if (len == -ESTRPIPE && rxm->accum_len) {
len = -ENODATA;
strp->rx_unrecov_intr = 1;
} else {
strp->rx_interrupted = 1;
}
strp_parser_err(strp, err, desc);
break;
} else if (len > strp->sk->sk_rcvbuf) {
/* Message length exceeds maximum allowed */
STRP_STATS_INCR(strp->stats.rx_msg_too_big);
strp_parser_err(strp, -EMSGSIZE, desc);
break;
} else if (len <= (ssize_t)head->len -
skb->len - rxm->strp.offset) {
/* Length must be into new skb (and also
* greater than zero)
*/
STRP_STATS_INCR(strp->stats.rx_bad_hdr_len);
strp_parser_err(strp, -EPROTO, desc);
break;
}
rxm->strp.full_len = len;
}
extra = (ssize_t)(rxm->accum_len + cand_len) -
rxm->strp.full_len;
if (extra < 0) {
/* Message not complete yet. */
if (rxm->strp.full_len - rxm->accum_len >
strp_peek_len(strp)) {
/* Don't have the whole messages in the socket
* buffer. Set strp->rx_need_bytes to wait for
* the rest of the message. Also, set "early
* eaten" since we've already buffered the skb
* but don't consume yet per strp_read_sock.
*/
if (!rxm->accum_len) {
/* Start RX timer for new message */
strp_start_rx_timer(strp);
}
strp->rx_need_bytes = rxm->strp.full_len -
rxm->accum_len;
rxm->accum_len += cand_len;
rxm->early_eaten = cand_len;
STRP_STATS_ADD(strp->stats.rx_bytes, cand_len);
desc->count = 0; /* Stop reading socket */
break;
}
rxm->accum_len += cand_len;
eaten += cand_len;
WARN_ON(eaten != orig_len);
break;
}
/* Positive extra indicates ore bytes than needed for the
* message
*/
WARN_ON(extra > cand_len);
eaten += (cand_len - extra);
/* Hurray, we have a new message! */
del_timer(&strp->rx_msg_timer);
strp->rx_skb_head = NULL;
STRP_STATS_INCR(strp->stats.rx_msgs);
/* Give skb to upper layer */
strp->cb.rcv_msg(strp, head);
if (unlikely(strp->rx_paused)) {
/* Upper layer paused strp */
break;
}
}
if (cloned_orig)
kfree_skb(orig_skb);
STRP_STATS_ADD(strp->stats.rx_bytes, eaten);
return eaten;
}
static int default_read_sock_done(struct strparser *strp, int err)
{
return err;
}
/* Called with lock held on lower socket */
static int strp_read_sock(struct strparser *strp)
{
struct socket *sock = strp->sk->sk_socket;
read_descriptor_t desc;
desc.arg.data = strp;
desc.error = 0;
desc.count = 1; /* give more than one skb per call */
/* sk should be locked here, so okay to do read_sock */
sock->ops->read_sock(strp->sk, &desc, strp_recv);
desc.error = strp->cb.read_sock_done(strp, desc.error);
return desc.error;
}
/* Lower sock lock held */
void strp_data_ready(struct strparser *strp)
{
if (unlikely(strp->rx_stopped))
return;
/* This check is needed to synchronize with do_strp_rx_work.
* do_strp_rx_work acquires a process lock (lock_sock) whereas
* the lock held here is bh_lock_sock. The two locks can be
* held by different threads at the same time, but bh_lock_sock
* allows a thread in BH context to safely check if the process
* lock is held. In this case, if the lock is held, queue work.
*/
if (sock_owned_by_user(strp->sk)) {
queue_work(strp_wq, &strp->rx_work);
return;
}
if (strp->rx_paused)
return;
if (strp->rx_need_bytes) {
if (strp_peek_len(strp) >= strp->rx_need_bytes)
strp->rx_need_bytes = 0;
else
return;
}
if (strp_read_sock(strp) == -ENOMEM)
queue_work(strp_wq, &strp->rx_work);
}
EXPORT_SYMBOL_GPL(strp_data_ready);
static void do_strp_rx_work(struct strparser *strp)
{
read_descriptor_t rd_desc;
struct sock *csk = strp->sk;
/* We need the read lock to synchronize with strp_data_ready. We
* need the socket lock for calling strp_read_sock.
*/
lock_sock(csk);
if (unlikely(strp->rx_stopped))
goto out;
if (strp->rx_paused)
goto out;
rd_desc.arg.data = strp;
if (strp_read_sock(strp) == -ENOMEM)
queue_work(strp_wq, &strp->rx_work);
out:
release_sock(csk);
}
static void strp_rx_work(struct work_struct *w)
{
do_strp_rx_work(container_of(w, struct strparser, rx_work));
}
static void strp_rx_msg_timeout(unsigned long arg)
{
struct strparser *strp = (struct strparser *)arg;
/* Message assembly timed out */
STRP_STATS_INCR(strp->stats.rx_msg_timeouts);
lock_sock(strp->sk);
strp->cb.abort_parser(strp, ETIMEDOUT);
release_sock(strp->sk);
}
int strp_init(struct strparser *strp, struct sock *csk,
struct strp_callbacks *cb)
{
struct socket *sock = csk->sk_socket;
if (!cb || !cb->rcv_msg || !cb->parse_msg)
return -EINVAL;
if (!sock->ops->read_sock || !sock->ops->peek_len)
return -EAFNOSUPPORT;
memset(strp, 0, sizeof(*strp));
strp->sk = csk;
setup_timer(&strp->rx_msg_timer, strp_rx_msg_timeout,
(unsigned long)strp);
INIT_WORK(&strp->rx_work, strp_rx_work);
strp->cb.rcv_msg = cb->rcv_msg;
strp->cb.parse_msg = cb->parse_msg;
strp->cb.read_sock_done = cb->read_sock_done ? : default_read_sock_done;
strp->cb.abort_parser = cb->abort_parser ? : strp_abort_rx_strp;
return 0;
}
EXPORT_SYMBOL_GPL(strp_init);
void strp_unpause(struct strparser *strp)
{
strp->rx_paused = 0;
/* Sync setting rx_paused with RX work */
smp_mb();
queue_work(strp_wq, &strp->rx_work);
}
EXPORT_SYMBOL_GPL(strp_unpause);
/* strp must already be stopped so that strp_recv will no longer be called.
* Note that strp_done is not called with the lower socket held.
*/
void strp_done(struct strparser *strp)
{
WARN_ON(!strp->rx_stopped);
del_timer_sync(&strp->rx_msg_timer);
cancel_work_sync(&strp->rx_work);
if (strp->rx_skb_head) {
kfree_skb(strp->rx_skb_head);
strp->rx_skb_head = NULL;
}
}
EXPORT_SYMBOL_GPL(strp_done);
void strp_stop(struct strparser *strp)
{
strp->rx_stopped = 1;
}
EXPORT_SYMBOL_GPL(strp_stop);
void strp_check_rcv(struct strparser *strp)
{
queue_work(strp_wq, &strp->rx_work);
}
EXPORT_SYMBOL_GPL(strp_check_rcv);
static int __init strp_mod_init(void)
{
strp_wq = create_singlethread_workqueue("kstrp");
return 0;
}
static void __exit strp_mod_exit(void)
{
}
module_init(strp_mod_init);
module_exit(strp_mod_exit);
MODULE_LICENSE("GPL");