linux/net/strparser/strparser.c at master · multikernel/linux · GitHub

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// SPDX-License-Identifier: GPL-2.0-only

* Stream Parser

#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/export.h>

#include <linux/init.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;

static inline struct _strp_msg *_strp_msg(struct sk_buff *skb)

{

return (struct _strp_msg *)((void *)skb->cb +

offsetof(struct sk_skb_cb, strp));

}

/* Lower lock held */

static void strp_abort_strp(struct strparser *strp, int err)

{

/* Unrecoverable error in receive */

cancel_delayed_work(&strp->msg_timer_work);

if (strp->stopped)

return;

strp->stopped = 1;

if (strp->sk) {

struct sock *sk = strp->sk;

/* Report an error on the lower socket */

sk->sk_err = -err;

sk_error_report(sk);

}

static void strp_start_timer(struct strparser *strp, long timeo)

{

if (timeo && timeo != LONG_MAX)

mod_delayed_work(strp_wq, &strp->msg_timer_work, timeo);

}

/* Lower lock held */

static void strp_parser_err(struct strparser *strp, int err,

read_descriptor_t *desc)

{

desc->error = err;

kfree_skb(strp->skb_head);

strp->skb_head = NULL;

strp->cb.abort_parser(strp, err);

}

static inline int strp_peek_len(struct strparser *strp)

{

if (strp->sk) {

struct socket *sock = strp->sk->sk_socket;

return sock->ops->peek_len(sock);

}

/* If we don't have an associated socket there's nothing to peek.

* Return int max to avoid stopping the strparser.

return INT_MAX;

}

/* 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,

size_t max_msg_size, long timeo)

{

struct strparser *strp = (struct strparser *)desc->arg.data;

struct _strp_msg *stm;

struct sk_buff *head, *skb;

size_t eaten = 0, cand_len;

ssize_t extra;

int err;

bool cloned_orig = false;

if (strp->paused)

return 0;

head = strp->skb_head;

if (head) {

/* Message already in progress */

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.mem_fail);

desc->error = -ENOMEM;

return 0;

}

if (!pskb_pull(orig_skb, orig_offset)) {

STRP_STATS_INCR(strp->stats.mem_fail);

kfree_skb(orig_skb);

desc->error = -ENOMEM;

return 0;

}

cloned_orig = true;

orig_offset = 0;

}

if (!strp->skb_nextp) {

/* We are going to append to the frag_list of head.

* Need to unshare the frag_list.

err = skb_unclone(head, GFP_ATOMIC);

if (err) {

STRP_STATS_INCR(strp->stats.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_for_msg(head);

if (!skb) {

STRP_STATS_INCR(strp->stats.mem_fail);

desc->error = -ENOMEM;

return 0;

}

strp->skb_nextp = &head->next;

strp->skb_head = skb;

head = skb;

} else {

strp->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.mem_fail);

desc->error = -ENOMEM;

break;

}

cand_len = orig_len - eaten;

head = strp->skb_head;

if (!head) {

head = skb;

strp->skb_head = head;

/* Will set skb_nextp on next packet if needed */

strp->skb_nextp = NULL;

stm = _strp_msg(head);

memset(stm, 0, sizeof(*stm));

stm->strp.offset = orig_offset + eaten;

} else {

/* Unclone if we are appending to an skb that we

* already share a frag_list with.

if (skb_has_frag_list(skb)) {

err = skb_unclone(skb, GFP_ATOMIC);

if (err) {

STRP_STATS_INCR(strp->stats.mem_fail);

desc->error = err;

break;

}

stm = _strp_msg(head);

*strp->skb_nextp = skb;

strp->skb_nextp = &skb->next;

head->data_len += skb->len;

head->len += skb->len;

head->truesize += skb->truesize;

}

if (!stm->strp.full_len) {

ssize_t len;

len = (*strp->cb.parse_msg)(strp, head);

if (!len) {

/* Need more header to determine length */

if (!stm->accum_len) {

/* Start RX timer for new message */

strp_start_timer(strp, timeo);

}

stm->accum_len += cand_len;

eaten += cand_len;

STRP_STATS_INCR(strp->stats.need_more_hdr);

WARN_ON(eaten != orig_len);

break;

} else if (len < 0) {

if (len == -ESTRPIPE && stm->accum_len) {

len = -ENODATA;

strp->unrecov_intr = 1;

} else {

strp->interrupted = 1;

}

strp_parser_err(strp, len, desc);

break;

} else if (len > max_msg_size) {

/* Message length exceeds maximum allowed */

STRP_STATS_INCR(strp->stats.msg_too_big);

strp_parser_err(strp, -EMSGSIZE, desc);

break;

} else if (len <= (ssize_t)head->len -

(ssize_t)skb->len - stm->strp.offset) {

/* Length must be into new skb (and also

* greater than zero)

STRP_STATS_INCR(strp->stats.bad_hdr_len);

strp_parser_err(strp, -EPROTO, desc);

break;

}

stm->strp.full_len = len;

}

extra = (ssize_t)(stm->accum_len + cand_len) -

stm->strp.full_len;

if (extra < 0) {

/* Message not complete yet. */

if (stm->strp.full_len - stm->accum_len >

strp_peek_len(strp)) {

/* Don't have the whole message in the socket

* buffer. Set strp->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 (!stm->accum_len) {

/* Start RX timer for new message */

strp_start_timer(strp, timeo);

}

stm->accum_len += cand_len;

eaten += cand_len;

strp->need_bytes = stm->strp.full_len -

stm->accum_len;

STRP_STATS_ADD(strp->stats.bytes, cand_len);

desc->count = 0; /* Stop reading socket */

break;

}

stm->accum_len += cand_len;

eaten += cand_len;

WARN_ON(eaten != orig_len);

break;

}

/* Positive extra indicates more bytes than needed for the

* message

WARN_ON(extra > cand_len);

eaten += (cand_len - extra);

/* Hurray, we have a new message! */

cancel_delayed_work(&strp->msg_timer_work);

strp->skb_head = NULL;

strp->need_bytes = 0;

STRP_STATS_INCR(strp->stats.msgs);

/* Give skb to upper layer */

strp->cb.rcv_msg(strp, head);

if (unlikely(strp->paused)) {

/* Upper layer paused strp */

break;

}

if (cloned_orig)

kfree_skb(orig_skb);

STRP_STATS_ADD(strp->stats.bytes, eaten);

return eaten;

}

int strp_process(struct strparser *strp, struct sk_buff *orig_skb,

unsigned int orig_offset, size_t orig_len,

size_t max_msg_size, long timeo)

{

read_descriptor_t desc; /* Dummy arg to strp_recv */

desc.arg.data = strp;

return __strp_recv(&desc, orig_skb, orig_offset, orig_len,

max_msg_size, timeo);

}

EXPORT_SYMBOL_GPL(strp_process);

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;

return __strp_recv(desc, orig_skb, orig_offset, orig_len,

strp->sk->sk_rcvbuf, READ_ONCE(strp->sk->sk_rcvtimeo));

}

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;

if (unlikely(!sock || !sock->ops))

return -EBUSY;

if (unlikely(!strp->cb.read_sock && !sock->ops->read_sock))

return -EBUSY;

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 */

if (strp->cb.read_sock)

strp->cb.read_sock(strp, &desc, strp_recv);

else

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->stopped) || strp->paused)

return;

/* This check is needed to synchronize with do_strp_work.

* do_strp_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_nocheck(strp->sk)) {

queue_work(strp_wq, &strp->work);

return;

}

if (strp->need_bytes) {

if (strp_peek_len(strp) < strp->need_bytes)

return;

}

if (strp_read_sock(strp) == -ENOMEM)

queue_work(strp_wq, &strp->work);

}

EXPORT_SYMBOL_GPL(strp_data_ready);

static void do_strp_work(struct strparser *strp)

{

/* We need the read lock to synchronize with strp_data_ready. We

* need the socket lock for calling strp_read_sock.

strp->cb.lock(strp);

if (unlikely(strp->stopped))

goto out;

if (strp->paused)

goto out;

if (strp_read_sock(strp) == -ENOMEM)

queue_work(strp_wq, &strp->work);

out:

strp->cb.unlock(strp);

}

static void strp_work(struct work_struct *w)

{

do_strp_work(container_of(w, struct strparser, work));

}

static void strp_msg_timeout(struct work_struct *w)

{

struct strparser *strp = container_of(w, struct strparser,

msg_timer_work.work);

/* Message assembly timed out */

STRP_STATS_INCR(strp->stats.msg_timeouts);

strp->cb.lock(strp);

strp->cb.abort_parser(strp, -ETIMEDOUT);

strp->cb.unlock(strp);

}

static void strp_sock_lock(struct strparser *strp)

{

lock_sock(strp->sk);

}

static void strp_sock_unlock(struct strparser *strp)

{

release_sock(strp->sk);

}

int strp_init(struct strparser *strp, struct sock *sk,

const struct strp_callbacks *cb)

{

if (!cb || !cb->rcv_msg || !cb->parse_msg)

return -EINVAL;

/* The sk (sock) arg determines the mode of the stream parser.

* If the sock is set then the strparser is in receive callback mode.

* The upper layer calls strp_data_ready to kick receive processing

* and strparser calls the read_sock function on the socket to

* get packets.

* If the sock is not set then the strparser is in general mode.

* The upper layer calls strp_process for each skb to be parsed.

if (!sk) {

if (!cb->lock || !cb->unlock)

return -EINVAL;

}

memset(strp, 0, sizeof(*strp));

strp->sk = sk;

strp->cb.lock = cb->lock ? : strp_sock_lock;

strp->cb.unlock = cb->unlock ? : strp_sock_unlock;

strp->cb.rcv_msg = cb->rcv_msg;

strp->cb.parse_msg = cb->parse_msg;

strp->cb.read_sock = cb->read_sock;

strp->cb.read_sock_done = cb->read_sock_done ? : default_read_sock_done;

strp->cb.abort_parser = cb->abort_parser ? : strp_abort_strp;

INIT_DELAYED_WORK(&strp->msg_timer_work, strp_msg_timeout);

INIT_WORK(&strp->work, strp_work);

return 0;

}

EXPORT_SYMBOL_GPL(strp_init);

void strp_unpause(struct strparser *strp)

{

strp->paused = 0;

/* Sync setting paused with RX work */

smp_mb();

queue_work(strp_wq, &strp->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->stopped);

cancel_delayed_work_sync(&strp->msg_timer_work);

cancel_work_sync(&strp->work);

if (strp->skb_head) {

kfree_skb(strp->skb_head);

strp->skb_head = NULL;

}

EXPORT_SYMBOL_GPL(strp_done);

void strp_stop(struct strparser *strp)

{

strp->stopped = 1;

}

EXPORT_SYMBOL_GPL(strp_stop);

void strp_check_rcv(struct strparser *strp)

{

queue_work(strp_wq, &strp->work);

}

EXPORT_SYMBOL_GPL(strp_check_rcv);

static int __init strp_dev_init(void)

{

BUILD_BUG_ON(sizeof(struct sk_skb_cb) >

sizeof_field(struct sk_buff, cb));

strp_wq = create_singlethread_workqueue("kstrp");

if (unlikely(!strp_wq))

return -ENOMEM;

return 0;

}

device_initcall(strp_dev_init);

linux/net/strparser/strparser.c at master · multikernel/linux · GitHub

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