Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * inet fragments management
 *
 * 		Authors:	Pavel Emelyanov <xemul@openvz.org>
 *				Started as consolidation of ipv4/ip_fragment.c,
 *				ipv6/reassembly. and ipv6 nf conntrack reassembly
 */
 
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/rhashtable.h>
 
#include <net/sock.h>
#include <net/inet_frag.h>
#include <net/inet_ecn.h>
#include <net/ip.h>
#include <net/ipv6.h>
 
/* Use skb->cb to track consecutive/adjacent fragments coming at
 * the end of the queue. Nodes in the rb-tree queue will
 * contain "runs" of one or more adjacent fragments.
 *
 * Invariants:
 * - next_frag is NULL at the tail of a "run";
 * - the head of a "run" has the sum of all fragment lengths in frag_run_len.
 */
struct ipfrag_skb_cb {
<------>union {
<------><------>struct inet_skb_parm	h4;
<------><------>struct inet6_skb_parm	h6;
<------>};
<------>struct sk_buff		*next_frag;
<------>int			frag_run_len;
};
 
#define FRAG_CB(skb)		((struct ipfrag_skb_cb *)((skb)->cb))
 
static void fragcb_clear(struct sk_buff *skb)
{
<------>RB_CLEAR_NODE(&skb->rbnode);
<------>FRAG_CB(skb)->next_frag = NULL;
<------>FRAG_CB(skb)->frag_run_len = skb->len;
}
 
/* Append skb to the last "run". */
static void fragrun_append_to_last(struct inet_frag_queue *q,
<------><------><------><------>   struct sk_buff *skb)
{
<------>fragcb_clear(skb);
 
<------>FRAG_CB(q->last_run_head)->frag_run_len += skb->len;
<------>FRAG_CB(q->fragments_tail)->next_frag = skb;
<------>q->fragments_tail = skb;
}
 
/* Create a new "run" with the skb. */
static void fragrun_create(struct inet_frag_queue *q, struct sk_buff *skb)
{
<------>BUILD_BUG_ON(sizeof(struct ipfrag_skb_cb) > sizeof(skb->cb));
<------>fragcb_clear(skb);
 
<------>if (q->last_run_head)
<------><------>rb_link_node(&skb->rbnode, &q->last_run_head->rbnode,
<------><------><------>     &q->last_run_head->rbnode.rb_right);
<------>else
<------><------>rb_link_node(&skb->rbnode, NULL, &q->rb_fragments.rb_node);
<------>rb_insert_color(&skb->rbnode, &q->rb_fragments);
 
<------>q->fragments_tail = skb;
<------>q->last_run_head = skb;
}
 
/* Given the OR values of all fragments, apply RFC 3168 5.3 requirements
 * Value : 0xff if frame should be dropped.
 *         0 or INET_ECN_CE value, to be ORed in to final iph->tos field
 */
const u8 ip_frag_ecn_table[16] = {
<------>/* at least one fragment had CE, and others ECT_0 or ECT_1 */
<------>[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0]			= INET_ECN_CE,
<------>[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1]			= INET_ECN_CE,
<------>[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1]	= INET_ECN_CE,
 
<------>/* invalid combinations : drop frame */
<------>[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff,
<------>[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff,
<------>[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff,
<------>[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
<------>[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff,
<------>[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff,
<------>[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
};
EXPORT_SYMBOL(ip_frag_ecn_table);
 
int inet_frags_init(struct inet_frags *f)
{
<------>f->frags_cachep = kmem_cache_create(f->frags_cache_name, f->qsize, 0, 0,
<------><------><------><------><------>    NULL);
<------>if (!f->frags_cachep)
<------><------>return -ENOMEM;
 
<------>refcount_set(&f->refcnt, 1);
<------>init_completion(&f->completion);
<------>return 0;
}
EXPORT_SYMBOL(inet_frags_init);
 
void inet_frags_fini(struct inet_frags *f)
{
<------>if (refcount_dec_and_test(&f->refcnt))
<------><------>complete(&f->completion);
 
<------>wait_for_completion(&f->completion);
 
<------>kmem_cache_destroy(f->frags_cachep);
<------>f->frags_cachep = NULL;
}
EXPORT_SYMBOL(inet_frags_fini);
 
/* called from rhashtable_free_and_destroy() at netns_frags dismantle */
static void inet_frags_free_cb(void *ptr, void *arg)
{
<------>struct inet_frag_queue *fq = ptr;
<------>int count;
 
<------>count = del_timer_sync(&fq->timer) ? 1 : 0;
 
<------>spin_lock_bh(&fq->lock);
<------>if (!(fq->flags & INET_FRAG_COMPLETE)) {
<------><------>fq->flags |= INET_FRAG_COMPLETE;
<------><------>count++;
<------>} else if (fq->flags & INET_FRAG_HASH_DEAD) {
<------><------>count++;
<------>}
<------>spin_unlock_bh(&fq->lock);
 
<------>if (refcount_sub_and_test(count, &fq->refcnt))
<------><------>inet_frag_destroy(fq);
}
 
static void fqdir_work_fn(struct work_struct *work)
{
<------>struct fqdir *fqdir = container_of(work, struct fqdir, destroy_work);
<------>struct inet_frags *f = fqdir->f;
 
<------>rhashtable_free_and_destroy(&fqdir->rhashtable, inet_frags_free_cb, NULL);
 
<------>/* We need to make sure all ongoing call_rcu(..., inet_frag_destroy_rcu)
<------> * have completed, since they need to dereference fqdir.
<------> * Would it not be nice to have kfree_rcu_barrier() ? :)
<------> */
<------>rcu_barrier();
 
<------>if (refcount_dec_and_test(&f->refcnt))
<------><------>complete(&f->completion);
 
<------>kfree(fqdir);
}
 
int fqdir_init(struct fqdir **fqdirp, struct inet_frags *f, struct net *net)
{
<------>struct fqdir *fqdir = kzalloc(sizeof(*fqdir), GFP_KERNEL);
<------>int res;
 
<------>if (!fqdir)
<------><------>return -ENOMEM;
<------>fqdir->f = f;
<------>fqdir->net = net;
<------>res = rhashtable_init(&fqdir->rhashtable, &fqdir->f->rhash_params);
<------>if (res < 0) {
<------><------>kfree(fqdir);
<------><------>return res;
<------>}
<------>refcount_inc(&f->refcnt);
<------>*fqdirp = fqdir;
<------>return 0;
}
EXPORT_SYMBOL(fqdir_init);
 
void fqdir_exit(struct fqdir *fqdir)
{
<------>INIT_WORK(&fqdir->destroy_work, fqdir_work_fn);
<------>queue_work(system_wq, &fqdir->destroy_work);
}
EXPORT_SYMBOL(fqdir_exit);
 
void inet_frag_kill(struct inet_frag_queue *fq)
{
<------>if (del_timer(&fq->timer))
<------><------>refcount_dec(&fq->refcnt);
 
<------>if (!(fq->flags & INET_FRAG_COMPLETE)) {
<------><------>struct fqdir *fqdir = fq->fqdir;
 
<------><------>fq->flags |= INET_FRAG_COMPLETE;
<------><------>rcu_read_lock();
<------><------>/* The RCU read lock provides a memory barrier
<------><------> * guaranteeing that if fqdir->dead is false then
<------><------> * the hash table destruction will not start until
<------><------> * after we unlock.  Paired with fqdir_pre_exit().
<------><------> */
<------><------>if (!READ_ONCE(fqdir->dead)) {
<------><------><------>rhashtable_remove_fast(&fqdir->rhashtable, &fq->node,
<------><------><------><------><------>       fqdir->f->rhash_params);
<------><------><------>refcount_dec(&fq->refcnt);
<------><------>} else {
<------><------><------>fq->flags |= INET_FRAG_HASH_DEAD;
<------><------>}
<------><------>rcu_read_unlock();
<------>}
}
EXPORT_SYMBOL(inet_frag_kill);
 
static void inet_frag_destroy_rcu(struct rcu_head *head)
{
<------>struct inet_frag_queue *q = container_of(head, struct inet_frag_queue,
<------><------><------><------><------><------> rcu);
<------>struct inet_frags *f = q->fqdir->f;
 
<------>if (f->destructor)
<------><------>f->destructor(q);
<------>kmem_cache_free(f->frags_cachep, q);
}
 
unsigned int inet_frag_rbtree_purge(struct rb_root *root)
{
<------>struct rb_node *p = rb_first(root);
<------>unsigned int sum = 0;
 
<------>while (p) {
<------><------>struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
 
<------><------>p = rb_next(p);
<------><------>rb_erase(&skb->rbnode, root);
<------><------>while (skb) {
<------><------><------>struct sk_buff *next = FRAG_CB(skb)->next_frag;
 
<------><------><------>sum += skb->truesize;
<------><------><------>kfree_skb(skb);
<------><------><------>skb = next;
<------><------>}
<------>}
<------>return sum;
}
EXPORT_SYMBOL(inet_frag_rbtree_purge);
 
void inet_frag_destroy(struct inet_frag_queue *q)
{
<------>struct fqdir *fqdir;
<------>unsigned int sum, sum_truesize = 0;
<------>struct inet_frags *f;
 
<------>WARN_ON(!(q->flags & INET_FRAG_COMPLETE));
<------>WARN_ON(del_timer(&q->timer) != 0);
 
<------>/* Release all fragment data. */
<------>fqdir = q->fqdir;
<------>f = fqdir->f;
<------>sum_truesize = inet_frag_rbtree_purge(&q->rb_fragments);
<------>sum = sum_truesize + f->qsize;
 
<------>call_rcu(&q->rcu, inet_frag_destroy_rcu);
 
<------>sub_frag_mem_limit(fqdir, sum);
}
EXPORT_SYMBOL(inet_frag_destroy);
 
static struct inet_frag_queue *inet_frag_alloc(struct fqdir *fqdir,
<------><------><------><------><------>       struct inet_frags *f,
<------><------><------><------><------>       void *arg)
{
<------>struct inet_frag_queue *q;
 
<------>q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
<------>if (!q)
<------><------>return NULL;
 
<------>q->fqdir = fqdir;
<------>f->constructor(q, arg);
<------>add_frag_mem_limit(fqdir, f->qsize);
 
<------>timer_setup(&q->timer, f->frag_expire, 0);
<------>spin_lock_init(&q->lock);
<------>refcount_set(&q->refcnt, 3);
 
<------>return q;
}
 
static struct inet_frag_queue *inet_frag_create(struct fqdir *fqdir,
<------><------><------><------><------><------>void *arg,
<------><------><------><------><------><------>struct inet_frag_queue **prev)
{
<------>struct inet_frags *f = fqdir->f;
<------>struct inet_frag_queue *q;
 
<------>q = inet_frag_alloc(fqdir, f, arg);
<------>if (!q) {
<------><------>*prev = ERR_PTR(-ENOMEM);
<------><------>return NULL;
<------>}
<------>mod_timer(&q->timer, jiffies + fqdir->timeout);
 
<------>*prev = rhashtable_lookup_get_insert_key(&fqdir->rhashtable, &q->key,
<------><------><------><------><------><------> &q->node, f->rhash_params);
<------>if (*prev) {
<------><------>q->flags |= INET_FRAG_COMPLETE;
<------><------>inet_frag_kill(q);
<------><------>inet_frag_destroy(q);
<------><------>return NULL;
<------>}
<------>return q;
}
 
/* TODO : call from rcu_read_lock() and no longer use refcount_inc_not_zero() */
struct inet_frag_queue *inet_frag_find(struct fqdir *fqdir, void *key)
{
<------>/* This pairs with WRITE_ONCE() in fqdir_pre_exit(). */
<------>long high_thresh = READ_ONCE(fqdir->high_thresh);
<------>struct inet_frag_queue *fq = NULL, *prev;
 
<------>if (!high_thresh || frag_mem_limit(fqdir) > high_thresh)
<------><------>return NULL;
 
<------>rcu_read_lock();
 
<------>prev = rhashtable_lookup(&fqdir->rhashtable, key, fqdir->f->rhash_params);
<------>if (!prev)
<------><------>fq = inet_frag_create(fqdir, key, &prev);
<------>if (!IS_ERR_OR_NULL(prev)) {
<------><------>fq = prev;
<------><------>if (!refcount_inc_not_zero(&fq->refcnt))
<------><------><------>fq = NULL;
<------>}
<------>rcu_read_unlock();
<------>return fq;
}
EXPORT_SYMBOL(inet_frag_find);
 
int inet_frag_queue_insert(struct inet_frag_queue *q, struct sk_buff *skb,
<------><------><------>   int offset, int end)
{
<------>struct sk_buff *last = q->fragments_tail;
 
<------>/* RFC5722, Section 4, amended by Errata ID : 3089
<------> *                          When reassembling an IPv6 datagram, if
<------> *   one or more its constituent fragments is determined to be an
<------> *   overlapping fragment, the entire datagram (and any constituent
<------> *   fragments) MUST be silently discarded.
<------> *
<------> * Duplicates, however, should be ignored (i.e. skb dropped, but the
<------> * queue/fragments kept for later reassembly).
<------> */
<------>if (!last)
<------><------>fragrun_create(q, skb);  /* First fragment. */
<------>else if (last->ip_defrag_offset + last->len < end) {
<------><------>/* This is the common case: skb goes to the end. */
<------><------>/* Detect and discard overlaps. */
<------><------>if (offset < last->ip_defrag_offset + last->len)
<------><------><------>return IPFRAG_OVERLAP;
<------><------>if (offset == last->ip_defrag_offset + last->len)
<------><------><------>fragrun_append_to_last(q, skb);
<------><------>else
<------><------><------>fragrun_create(q, skb);
<------>} else {
<------><------>/* Binary search. Note that skb can become the first fragment,
<------><------> * but not the last (covered above).
<------><------> */
<------><------>struct rb_node **rbn, *parent;
 
<------><------>rbn = &q->rb_fragments.rb_node;
<------><------>do {
<------><------><------>struct sk_buff *curr;
<------><------><------>int curr_run_end;
 
<------><------><------>parent = *rbn;
<------><------><------>curr = rb_to_skb(parent);
<------><------><------>curr_run_end = curr->ip_defrag_offset +
<------><------><------><------><------>FRAG_CB(curr)->frag_run_len;
<------><------><------>if (end <= curr->ip_defrag_offset)
<------><------><------><------>rbn = &parent->rb_left;
<------><------><------>else if (offset >= curr_run_end)
<------><------><------><------>rbn = &parent->rb_right;
<------><------><------>else if (offset >= curr->ip_defrag_offset &&
<------><------><------><------> end <= curr_run_end)
<------><------><------><------>return IPFRAG_DUP;
<------><------><------>else
<------><------><------><------>return IPFRAG_OVERLAP;
<------><------>} while (*rbn);
<------><------>/* Here we have parent properly set, and rbn pointing to
<------><------> * one of its NULL left/right children. Insert skb.
<------><------> */
<------><------>fragcb_clear(skb);
<------><------>rb_link_node(&skb->rbnode, parent, rbn);
<------><------>rb_insert_color(&skb->rbnode, &q->rb_fragments);
<------>}
 
<------>skb->ip_defrag_offset = offset;
 
<------>return IPFRAG_OK;
}
EXPORT_SYMBOL(inet_frag_queue_insert);
 
void *inet_frag_reasm_prepare(struct inet_frag_queue *q, struct sk_buff *skb,
<------><------><------>      struct sk_buff *parent)
{
<------>struct sk_buff *fp, *head = skb_rb_first(&q->rb_fragments);
<------>struct sk_buff **nextp;
<------>int delta;
 
<------>if (head != skb) {
<------><------>fp = skb_clone(skb, GFP_ATOMIC);
<------><------>if (!fp)
<------><------><------>return NULL;
<------><------>FRAG_CB(fp)->next_frag = FRAG_CB(skb)->next_frag;
<------><------>if (RB_EMPTY_NODE(&skb->rbnode))
<------><------><------>FRAG_CB(parent)->next_frag = fp;
<------><------>else
<------><------><------>rb_replace_node(&skb->rbnode, &fp->rbnode,
<------><------><------><------><------>&q->rb_fragments);
<------><------>if (q->fragments_tail == skb)
<------><------><------>q->fragments_tail = fp;
<------><------>skb_morph(skb, head);
<------><------>FRAG_CB(skb)->next_frag = FRAG_CB(head)->next_frag;
<------><------>rb_replace_node(&head->rbnode, &skb->rbnode,
<------><------><------><------>&q->rb_fragments);
<------><------>consume_skb(head);
<------><------>head = skb;
<------>}
<------>WARN_ON(head->ip_defrag_offset != 0);
 
<------>delta = -head->truesize;
 
<------>/* Head of list must not be cloned. */
<------>if (skb_unclone(head, GFP_ATOMIC))
<------><------>return NULL;
 
<------>delta += head->truesize;
<------>if (delta)
<------><------>add_frag_mem_limit(q->fqdir, delta);
 
<------>/* If the first fragment is fragmented itself, we split
<------> * it to two chunks: the first with data and paged part
<------> * and the second, holding only fragments.
<------> */
<------>if (skb_has_frag_list(head)) {
<------><------>struct sk_buff *clone;
<------><------>int i, plen = 0;
 
<------><------>clone = alloc_skb(0, GFP_ATOMIC);
<------><------>if (!clone)
<------><------><------>return NULL;
<------><------>skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
<------><------>skb_frag_list_init(head);
<------><------>for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
<------><------><------>plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
<------><------>clone->data_len = head->data_len - plen;
<------><------>clone->len = clone->data_len;
<------><------>head->truesize += clone->truesize;
<------><------>clone->csum = 0;
<------><------>clone->ip_summed = head->ip_summed;
<------><------>add_frag_mem_limit(q->fqdir, clone->truesize);
<------><------>skb_shinfo(head)->frag_list = clone;
<------><------>nextp = &clone->next;
<------>} else {
<------><------>nextp = &skb_shinfo(head)->frag_list;
<------>}
 
<------>return nextp;
}
EXPORT_SYMBOL(inet_frag_reasm_prepare);
 
void inet_frag_reasm_finish(struct inet_frag_queue *q, struct sk_buff *head,
<------><------><------>    void *reasm_data, bool try_coalesce)
{
<------>struct sk_buff **nextp = (struct sk_buff **)reasm_data;
<------>struct rb_node *rbn;
<------>struct sk_buff *fp;
<------>int sum_truesize;
 
<------>skb_push(head, head->data - skb_network_header(head));
 
<------>/* Traverse the tree in order, to build frag_list. */
<------>fp = FRAG_CB(head)->next_frag;
<------>rbn = rb_next(&head->rbnode);
<------>rb_erase(&head->rbnode, &q->rb_fragments);
 
<------>sum_truesize = head->truesize;
<------>while (rbn || fp) {
<------><------>/* fp points to the next sk_buff in the current run;
<------><------> * rbn points to the next run.
<------><------> */
<------><------>/* Go through the current run. */
<------><------>while (fp) {
<------><------><------>struct sk_buff *next_frag = FRAG_CB(fp)->next_frag;
<------><------><------>bool stolen;
<------><------><------>int delta;
 
<------><------><------>sum_truesize += fp->truesize;
<------><------><------>if (head->ip_summed != fp->ip_summed)
<------><------><------><------>head->ip_summed = CHECKSUM_NONE;
<------><------><------>else if (head->ip_summed == CHECKSUM_COMPLETE)
<------><------><------><------>head->csum = csum_add(head->csum, fp->csum);
 
<------><------><------>if (try_coalesce && skb_try_coalesce(head, fp, &stolen,
<------><------><------><------><------><------><------>     &delta)) {
<------><------><------><------>kfree_skb_partial(fp, stolen);
<------><------><------>} else {
<------><------><------><------>fp->prev = NULL;
<------><------><------><------>memset(&fp->rbnode, 0, sizeof(fp->rbnode));
<------><------><------><------>fp->sk = NULL;
 
<------><------><------><------>head->data_len += fp->len;
<------><------><------><------>head->len += fp->len;
<------><------><------><------>head->truesize += fp->truesize;
 
<------><------><------><------>*nextp = fp;
<------><------><------><------>nextp = &fp->next;
<------><------><------>}
 
<------><------><------>fp = next_frag;
<------><------>}
<------><------>/* Move to the next run. */
<------><------>if (rbn) {
<------><------><------>struct rb_node *rbnext = rb_next(rbn);
 
<------><------><------>fp = rb_to_skb(rbn);
<------><------><------>rb_erase(rbn, &q->rb_fragments);
<------><------><------>rbn = rbnext;
<------><------>}
<------>}
<------>sub_frag_mem_limit(q->fqdir, sum_truesize);
 
<------>*nextp = NULL;
<------>skb_mark_not_on_list(head);
<------>head->prev = NULL;
<------>head->tstamp = q->stamp;
}
EXPORT_SYMBOL(inet_frag_reasm_finish);
 
struct sk_buff *inet_frag_pull_head(struct inet_frag_queue *q)
{
<------>struct sk_buff *head, *skb;
 
<------>head = skb_rb_first(&q->rb_fragments);
<------>if (!head)
<------><------>return NULL;
<------>skb = FRAG_CB(head)->next_frag;
<------>if (skb)
<------><------>rb_replace_node(&head->rbnode, &skb->rbnode,
<------><------><------><------>&q->rb_fragments);
<------>else
<------><------>rb_erase(&head->rbnode, &q->rb_fragments);
<------>memset(&head->rbnode, 0, sizeof(head->rbnode));
<------>barrier();
 
<------>if (head == q->fragments_tail)
<------><------>q->fragments_tail = NULL;
 
<------>sub_frag_mem_limit(q->fqdir, head->truesize);
 
<------>return head;
}
EXPORT_SYMBOL(inet_frag_pull_head);