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![Taehee Yoo](/assets/img/avatar_default.png)
A kernel crash occurrs when defragmented packet is fragmented
in ip_do_fragment().
In defragment routine, skb_orphan() is called and
skb->ip_defrag_offset is set. but skb->sk and
skb->ip_defrag_offset are same union member. so that
frag->sk is not NULL.
Hence crash occurrs in skb->sk check routine in ip_do_fragment() when
defragmented packet is fragmented.
test commands:
%iptables -t nat -I POSTROUTING -j MASQUERADE
%hping3 192.168.4.2 -s 1000 -p 2000 -d 60000
splat looks like:
[ 261.069429] kernel BUG at net/ipv4/ip_output.c:636!
[ 261.075753] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
[ 261.083854] CPU: 1 PID: 1349 Comm: hping3 Not tainted 4.19.0-rc2+ #3
[ 261.100977] RIP: 0010:ip_do_fragment+0x1613/0x2600
[ 261.106945] Code: e8 e2 38 e3 fe 4c 8b 44 24 18 48 8b 74 24 08 e9 92 f6 ff ff 80 3c 02 00 0f 85 da 07 00 00 48 8b b5 d0 00 00 00 e9 25 f6 ff ff <0f> 0b 0f 0b 44 8b 54 24 58 4c 8b 4c 24 18 4c 8b 5c 24 60 4c 8b 6c
[ 261.127015] RSP: 0018:ffff8801031cf2c0 EFLAGS: 00010202
[ 261.134156] RAX: 1ffff1002297537b RBX: ffffed0020639e6e RCX: 0000000000000004
[ 261.142156] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880114ba9bd8
[ 261.150157] RBP: ffff880114ba8a40 R08: ffffed0022975395 R09: ffffed0022975395
[ 261.158157] R10: 0000000000000001 R11: ffffed0022975394 R12: ffff880114ba9ca4
[ 261.166159] R13: 0000000000000010 R14: ffff880114ba9bc0 R15: dffffc0000000000
[ 261.174169] FS: 00007fbae2199700(0000) GS:ffff88011b400000(0000) knlGS:0000000000000000
[ 261.183012] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 261.189013] CR2: 00005579244fe000 CR3: 0000000119bf4000 CR4: 00000000001006e0
[ 261.198158] Call Trace:
[ 261.199018] ? dst_output+0x180/0x180
[ 261.205011] ? save_trace+0x300/0x300
[ 261.209018] ? ip_copy_metadata+0xb00/0xb00
[ 261.213034] ? sched_clock_local+0xd4/0x140
[ 261.218158] ? kill_l4proto+0x120/0x120 [nf_conntrack]
[ 261.223014] ? rt_cpu_seq_stop+0x10/0x10
[ 261.227014] ? find_held_lock+0x39/0x1c0
[ 261.233008] ip_finish_output+0x51d/0xb50
[ 261.237006] ? ip_fragment.constprop.56+0x220/0x220
[ 261.243011] ? nf_ct_l4proto_register_one+0x5b0/0x5b0 [nf_conntrack]
[ 261.250152] ? rcu_is_watching+0x77/0x120
[ 261.255010] ? nf_nat_ipv4_out+0x1e/0x2b0 [nf_nat_ipv4]
[ 261.261033] ? nf_hook_slow+0xb1/0x160
[ 261.265007] ip_output+0x1c7/0x710
[ 261.269005] ? ip_mc_output+0x13f0/0x13f0
[ 261.273002] ? __local_bh_enable_ip+0xe9/0x1b0
[ 261.278152] ? ip_fragment.constprop.56+0x220/0x220
[ 261.282996] ? nf_hook_slow+0xb1/0x160
[ 261.287007] raw_sendmsg+0x21f9/0x4420
[ 261.291008] ? dst_output+0x180/0x180
[ 261.297003] ? sched_clock_cpu+0x126/0x170
[ 261.301003] ? find_held_lock+0x39/0x1c0
[ 261.306155] ? stop_critical_timings+0x420/0x420
[ 261.311004] ? check_flags.part.36+0x450/0x450
[ 261.315005] ? _raw_spin_unlock_irq+0x29/0x40
[ 261.320995] ? _raw_spin_unlock_irq+0x29/0x40
[ 261.326142] ? cyc2ns_read_end+0x10/0x10
[ 261.330139] ? raw_bind+0x280/0x280
[ 261.334138] ? sched_clock_cpu+0x126/0x170
[ 261.338995] ? check_flags.part.36+0x450/0x450
[ 261.342991] ? __lock_acquire+0x4500/0x4500
[ 261.348994] ? inet_sendmsg+0x11c/0x500
[ 261.352989] ? dst_output+0x180/0x180
[ 261.357012] inet_sendmsg+0x11c/0x500
[ ... ]
v2:
- clear skb->sk at reassembly routine.(Eric Dumarzet)
Fixes: fa0f527358
("ip: use rb trees for IP frag queue.")
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
967 lines
24 KiB
C
967 lines
24 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* The IP fragmentation functionality.
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*
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* Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG>
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* Alan Cox <alan@lxorguk.ukuu.org.uk>
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*
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* Fixes:
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* Alan Cox : Split from ip.c , see ip_input.c for history.
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* David S. Miller : Begin massive cleanup...
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* Andi Kleen : Add sysctls.
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* xxxx : Overlapfrag bug.
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* Ultima : ip_expire() kernel panic.
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* Bill Hawes : Frag accounting and evictor fixes.
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* John McDonald : 0 length frag bug.
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* Alexey Kuznetsov: SMP races, threading, cleanup.
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* Patrick McHardy : LRU queue of frag heads for evictor.
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*/
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#define pr_fmt(fmt) "IPv4: " fmt
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#include <linux/compiler.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/jiffies.h>
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#include <linux/skbuff.h>
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#include <linux/list.h>
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#include <linux/ip.h>
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#include <linux/icmp.h>
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#include <linux/netdevice.h>
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#include <linux/jhash.h>
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#include <linux/random.h>
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#include <linux/slab.h>
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#include <net/route.h>
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#include <net/dst.h>
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#include <net/sock.h>
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#include <net/ip.h>
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#include <net/icmp.h>
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#include <net/checksum.h>
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#include <net/inetpeer.h>
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#include <net/inet_frag.h>
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#include <linux/tcp.h>
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#include <linux/udp.h>
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#include <linux/inet.h>
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#include <linux/netfilter_ipv4.h>
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#include <net/inet_ecn.h>
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#include <net/l3mdev.h>
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/* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6
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* code now. If you change something here, _PLEASE_ update ipv6/reassembly.c
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* as well. Or notify me, at least. --ANK
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*/
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static const char ip_frag_cache_name[] = "ip4-frags";
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/* Use skb->cb to track consecutive/adjacent fragments coming at
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* the end of the queue. Nodes in the rb-tree queue will
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* contain "runs" of one or more adjacent fragments.
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*
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* Invariants:
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* - next_frag is NULL at the tail of a "run";
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* - the head of a "run" has the sum of all fragment lengths in frag_run_len.
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*/
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struct ipfrag_skb_cb {
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struct inet_skb_parm h;
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struct sk_buff *next_frag;
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int frag_run_len;
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};
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#define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb))
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static void ip4_frag_init_run(struct sk_buff *skb)
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{
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BUILD_BUG_ON(sizeof(struct ipfrag_skb_cb) > sizeof(skb->cb));
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FRAG_CB(skb)->next_frag = NULL;
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FRAG_CB(skb)->frag_run_len = skb->len;
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}
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/* Append skb to the last "run". */
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static void ip4_frag_append_to_last_run(struct inet_frag_queue *q,
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struct sk_buff *skb)
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{
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RB_CLEAR_NODE(&skb->rbnode);
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FRAG_CB(skb)->next_frag = NULL;
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FRAG_CB(q->last_run_head)->frag_run_len += skb->len;
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FRAG_CB(q->fragments_tail)->next_frag = skb;
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q->fragments_tail = skb;
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}
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/* Create a new "run" with the skb. */
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static void ip4_frag_create_run(struct inet_frag_queue *q, struct sk_buff *skb)
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{
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if (q->last_run_head)
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rb_link_node(&skb->rbnode, &q->last_run_head->rbnode,
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&q->last_run_head->rbnode.rb_right);
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else
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rb_link_node(&skb->rbnode, NULL, &q->rb_fragments.rb_node);
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rb_insert_color(&skb->rbnode, &q->rb_fragments);
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ip4_frag_init_run(skb);
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q->fragments_tail = skb;
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q->last_run_head = skb;
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}
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/* Describe an entry in the "incomplete datagrams" queue. */
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struct ipq {
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struct inet_frag_queue q;
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u8 ecn; /* RFC3168 support */
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u16 max_df_size; /* largest frag with DF set seen */
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int iif;
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unsigned int rid;
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struct inet_peer *peer;
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};
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static u8 ip4_frag_ecn(u8 tos)
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{
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return 1 << (tos & INET_ECN_MASK);
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}
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static struct inet_frags ip4_frags;
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static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
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struct sk_buff *prev_tail, struct net_device *dev);
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static void ip4_frag_init(struct inet_frag_queue *q, const void *a)
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{
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struct ipq *qp = container_of(q, struct ipq, q);
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struct netns_ipv4 *ipv4 = container_of(q->net, struct netns_ipv4,
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frags);
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struct net *net = container_of(ipv4, struct net, ipv4);
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const struct frag_v4_compare_key *key = a;
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q->key.v4 = *key;
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qp->ecn = 0;
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qp->peer = q->net->max_dist ?
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inet_getpeer_v4(net->ipv4.peers, key->saddr, key->vif, 1) :
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NULL;
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}
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static void ip4_frag_free(struct inet_frag_queue *q)
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{
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struct ipq *qp;
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qp = container_of(q, struct ipq, q);
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if (qp->peer)
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inet_putpeer(qp->peer);
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}
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/* Destruction primitives. */
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static void ipq_put(struct ipq *ipq)
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{
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inet_frag_put(&ipq->q);
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}
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/* Kill ipq entry. It is not destroyed immediately,
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* because caller (and someone more) holds reference count.
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*/
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static void ipq_kill(struct ipq *ipq)
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{
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inet_frag_kill(&ipq->q);
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}
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static bool frag_expire_skip_icmp(u32 user)
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{
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return user == IP_DEFRAG_AF_PACKET ||
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ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_IN,
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__IP_DEFRAG_CONNTRACK_IN_END) ||
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ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_BRIDGE_IN,
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__IP_DEFRAG_CONNTRACK_BRIDGE_IN);
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}
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/*
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* Oops, a fragment queue timed out. Kill it and send an ICMP reply.
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*/
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static void ip_expire(struct timer_list *t)
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{
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struct inet_frag_queue *frag = from_timer(frag, t, timer);
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const struct iphdr *iph;
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struct sk_buff *head = NULL;
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struct net *net;
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struct ipq *qp;
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int err;
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qp = container_of(frag, struct ipq, q);
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net = container_of(qp->q.net, struct net, ipv4.frags);
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rcu_read_lock();
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spin_lock(&qp->q.lock);
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if (qp->q.flags & INET_FRAG_COMPLETE)
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goto out;
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ipq_kill(qp);
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__IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
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__IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT);
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if (!(qp->q.flags & INET_FRAG_FIRST_IN))
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goto out;
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/* sk_buff::dev and sk_buff::rbnode are unionized. So we
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* pull the head out of the tree in order to be able to
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* deal with head->dev.
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*/
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if (qp->q.fragments) {
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head = qp->q.fragments;
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qp->q.fragments = head->next;
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} else {
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head = skb_rb_first(&qp->q.rb_fragments);
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if (!head)
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goto out;
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if (FRAG_CB(head)->next_frag)
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rb_replace_node(&head->rbnode,
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&FRAG_CB(head)->next_frag->rbnode,
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&qp->q.rb_fragments);
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else
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rb_erase(&head->rbnode, &qp->q.rb_fragments);
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memset(&head->rbnode, 0, sizeof(head->rbnode));
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barrier();
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}
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if (head == qp->q.fragments_tail)
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qp->q.fragments_tail = NULL;
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sub_frag_mem_limit(qp->q.net, head->truesize);
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head->dev = dev_get_by_index_rcu(net, qp->iif);
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if (!head->dev)
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goto out;
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/* skb has no dst, perform route lookup again */
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iph = ip_hdr(head);
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err = ip_route_input_noref(head, iph->daddr, iph->saddr,
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iph->tos, head->dev);
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if (err)
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goto out;
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/* Only an end host needs to send an ICMP
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* "Fragment Reassembly Timeout" message, per RFC792.
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*/
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if (frag_expire_skip_icmp(qp->q.key.v4.user) &&
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(skb_rtable(head)->rt_type != RTN_LOCAL))
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goto out;
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spin_unlock(&qp->q.lock);
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icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
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goto out_rcu_unlock;
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out:
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spin_unlock(&qp->q.lock);
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out_rcu_unlock:
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rcu_read_unlock();
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if (head)
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kfree_skb(head);
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ipq_put(qp);
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}
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/* Find the correct entry in the "incomplete datagrams" queue for
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* this IP datagram, and create new one, if nothing is found.
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*/
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static struct ipq *ip_find(struct net *net, struct iphdr *iph,
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u32 user, int vif)
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{
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struct frag_v4_compare_key key = {
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.saddr = iph->saddr,
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.daddr = iph->daddr,
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.user = user,
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.vif = vif,
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.id = iph->id,
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.protocol = iph->protocol,
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};
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struct inet_frag_queue *q;
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q = inet_frag_find(&net->ipv4.frags, &key);
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if (!q)
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return NULL;
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return container_of(q, struct ipq, q);
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}
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/* Is the fragment too far ahead to be part of ipq? */
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static int ip_frag_too_far(struct ipq *qp)
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{
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struct inet_peer *peer = qp->peer;
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unsigned int max = qp->q.net->max_dist;
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unsigned int start, end;
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int rc;
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if (!peer || !max)
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return 0;
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start = qp->rid;
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end = atomic_inc_return(&peer->rid);
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qp->rid = end;
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rc = qp->q.fragments_tail && (end - start) > max;
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if (rc) {
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struct net *net;
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net = container_of(qp->q.net, struct net, ipv4.frags);
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__IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
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}
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return rc;
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}
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static int ip_frag_reinit(struct ipq *qp)
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{
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unsigned int sum_truesize = 0;
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if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) {
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refcount_inc(&qp->q.refcnt);
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return -ETIMEDOUT;
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}
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sum_truesize = inet_frag_rbtree_purge(&qp->q.rb_fragments);
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sub_frag_mem_limit(qp->q.net, sum_truesize);
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qp->q.flags = 0;
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qp->q.len = 0;
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qp->q.meat = 0;
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qp->q.fragments = NULL;
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qp->q.rb_fragments = RB_ROOT;
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qp->q.fragments_tail = NULL;
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qp->q.last_run_head = NULL;
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qp->iif = 0;
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qp->ecn = 0;
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return 0;
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}
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/* Add new segment to existing queue. */
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static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
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{
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struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
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struct rb_node **rbn, *parent;
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struct sk_buff *skb1, *prev_tail;
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struct net_device *dev;
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unsigned int fragsize;
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int flags, offset;
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int ihl, end;
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int err = -ENOENT;
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u8 ecn;
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if (qp->q.flags & INET_FRAG_COMPLETE)
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goto err;
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if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) &&
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unlikely(ip_frag_too_far(qp)) &&
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unlikely(err = ip_frag_reinit(qp))) {
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ipq_kill(qp);
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goto err;
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}
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ecn = ip4_frag_ecn(ip_hdr(skb)->tos);
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offset = ntohs(ip_hdr(skb)->frag_off);
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flags = offset & ~IP_OFFSET;
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offset &= IP_OFFSET;
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offset <<= 3; /* offset is in 8-byte chunks */
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ihl = ip_hdrlen(skb);
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/* Determine the position of this fragment. */
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end = offset + skb->len - skb_network_offset(skb) - ihl;
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err = -EINVAL;
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/* Is this the final fragment? */
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if ((flags & IP_MF) == 0) {
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/* If we already have some bits beyond end
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* or have different end, the segment is corrupted.
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*/
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if (end < qp->q.len ||
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((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len))
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goto err;
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qp->q.flags |= INET_FRAG_LAST_IN;
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qp->q.len = end;
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} else {
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if (end&7) {
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end &= ~7;
|
|
if (skb->ip_summed != CHECKSUM_UNNECESSARY)
|
|
skb->ip_summed = CHECKSUM_NONE;
|
|
}
|
|
if (end > qp->q.len) {
|
|
/* Some bits beyond end -> corruption. */
|
|
if (qp->q.flags & INET_FRAG_LAST_IN)
|
|
goto err;
|
|
qp->q.len = end;
|
|
}
|
|
}
|
|
if (end == offset)
|
|
goto err;
|
|
|
|
err = -ENOMEM;
|
|
if (!pskb_pull(skb, skb_network_offset(skb) + ihl))
|
|
goto err;
|
|
|
|
err = pskb_trim_rcsum(skb, end - offset);
|
|
if (err)
|
|
goto err;
|
|
|
|
/* Note : skb->rbnode and skb->dev share the same location. */
|
|
dev = skb->dev;
|
|
/* Makes sure compiler wont do silly aliasing games */
|
|
barrier();
|
|
|
|
/* 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.
|
|
*
|
|
* We do the same here for IPv4 (and increment an snmp counter).
|
|
*/
|
|
|
|
/* Find out where to put this fragment. */
|
|
prev_tail = qp->q.fragments_tail;
|
|
if (!prev_tail)
|
|
ip4_frag_create_run(&qp->q, skb); /* First fragment. */
|
|
else if (prev_tail->ip_defrag_offset + prev_tail->len < end) {
|
|
/* This is the common case: skb goes to the end. */
|
|
/* Detect and discard overlaps. */
|
|
if (offset < prev_tail->ip_defrag_offset + prev_tail->len)
|
|
goto discard_qp;
|
|
if (offset == prev_tail->ip_defrag_offset + prev_tail->len)
|
|
ip4_frag_append_to_last_run(&qp->q, skb);
|
|
else
|
|
ip4_frag_create_run(&qp->q, skb);
|
|
} else {
|
|
/* Binary search. Note that skb can become the first fragment,
|
|
* but not the last (covered above).
|
|
*/
|
|
rbn = &qp->q.rb_fragments.rb_node;
|
|
do {
|
|
parent = *rbn;
|
|
skb1 = rb_to_skb(parent);
|
|
if (end <= skb1->ip_defrag_offset)
|
|
rbn = &parent->rb_left;
|
|
else if (offset >= skb1->ip_defrag_offset +
|
|
FRAG_CB(skb1)->frag_run_len)
|
|
rbn = &parent->rb_right;
|
|
else /* Found an overlap with skb1. */
|
|
goto discard_qp;
|
|
} while (*rbn);
|
|
/* Here we have parent properly set, and rbn pointing to
|
|
* one of its NULL left/right children. Insert skb.
|
|
*/
|
|
ip4_frag_init_run(skb);
|
|
rb_link_node(&skb->rbnode, parent, rbn);
|
|
rb_insert_color(&skb->rbnode, &qp->q.rb_fragments);
|
|
}
|
|
|
|
if (dev)
|
|
qp->iif = dev->ifindex;
|
|
skb->ip_defrag_offset = offset;
|
|
|
|
qp->q.stamp = skb->tstamp;
|
|
qp->q.meat += skb->len;
|
|
qp->ecn |= ecn;
|
|
add_frag_mem_limit(qp->q.net, skb->truesize);
|
|
if (offset == 0)
|
|
qp->q.flags |= INET_FRAG_FIRST_IN;
|
|
|
|
fragsize = skb->len + ihl;
|
|
|
|
if (fragsize > qp->q.max_size)
|
|
qp->q.max_size = fragsize;
|
|
|
|
if (ip_hdr(skb)->frag_off & htons(IP_DF) &&
|
|
fragsize > qp->max_df_size)
|
|
qp->max_df_size = fragsize;
|
|
|
|
if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
|
|
qp->q.meat == qp->q.len) {
|
|
unsigned long orefdst = skb->_skb_refdst;
|
|
|
|
skb->_skb_refdst = 0UL;
|
|
err = ip_frag_reasm(qp, skb, prev_tail, dev);
|
|
skb->_skb_refdst = orefdst;
|
|
return err;
|
|
}
|
|
|
|
skb_dst_drop(skb);
|
|
return -EINPROGRESS;
|
|
|
|
discard_qp:
|
|
inet_frag_kill(&qp->q);
|
|
err = -EINVAL;
|
|
__IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
|
|
err:
|
|
kfree_skb(skb);
|
|
return err;
|
|
}
|
|
|
|
/* Build a new IP datagram from all its fragments. */
|
|
static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
|
|
struct sk_buff *prev_tail, struct net_device *dev)
|
|
{
|
|
struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
|
|
struct iphdr *iph;
|
|
struct sk_buff *fp, *head = skb_rb_first(&qp->q.rb_fragments);
|
|
struct sk_buff **nextp; /* To build frag_list. */
|
|
struct rb_node *rbn;
|
|
int len;
|
|
int ihlen;
|
|
int err;
|
|
u8 ecn;
|
|
|
|
ipq_kill(qp);
|
|
|
|
ecn = ip_frag_ecn_table[qp->ecn];
|
|
if (unlikely(ecn == 0xff)) {
|
|
err = -EINVAL;
|
|
goto out_fail;
|
|
}
|
|
/* Make the one we just received the head. */
|
|
if (head != skb) {
|
|
fp = skb_clone(skb, GFP_ATOMIC);
|
|
if (!fp)
|
|
goto out_nomem;
|
|
FRAG_CB(fp)->next_frag = FRAG_CB(skb)->next_frag;
|
|
if (RB_EMPTY_NODE(&skb->rbnode))
|
|
FRAG_CB(prev_tail)->next_frag = fp;
|
|
else
|
|
rb_replace_node(&skb->rbnode, &fp->rbnode,
|
|
&qp->q.rb_fragments);
|
|
if (qp->q.fragments_tail == skb)
|
|
qp->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,
|
|
&qp->q.rb_fragments);
|
|
consume_skb(head);
|
|
head = skb;
|
|
}
|
|
|
|
WARN_ON(head->ip_defrag_offset != 0);
|
|
|
|
/* Allocate a new buffer for the datagram. */
|
|
ihlen = ip_hdrlen(head);
|
|
len = ihlen + qp->q.len;
|
|
|
|
err = -E2BIG;
|
|
if (len > 65535)
|
|
goto out_oversize;
|
|
|
|
/* Head of list must not be cloned. */
|
|
if (skb_unclone(head, GFP_ATOMIC))
|
|
goto out_nomem;
|
|
|
|
/* 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)
|
|
goto out_nomem;
|
|
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->len = clone->data_len = head->data_len - plen;
|
|
head->truesize += clone->truesize;
|
|
clone->csum = 0;
|
|
clone->ip_summed = head->ip_summed;
|
|
add_frag_mem_limit(qp->q.net, clone->truesize);
|
|
skb_shinfo(head)->frag_list = clone;
|
|
nextp = &clone->next;
|
|
} else {
|
|
nextp = &skb_shinfo(head)->frag_list;
|
|
}
|
|
|
|
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, &qp->q.rb_fragments);
|
|
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) {
|
|
*nextp = fp;
|
|
nextp = &fp->next;
|
|
fp->prev = NULL;
|
|
memset(&fp->rbnode, 0, sizeof(fp->rbnode));
|
|
fp->sk = NULL;
|
|
head->data_len += fp->len;
|
|
head->len += fp->len;
|
|
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);
|
|
head->truesize += fp->truesize;
|
|
fp = FRAG_CB(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, &qp->q.rb_fragments);
|
|
rbn = rbnext;
|
|
}
|
|
}
|
|
sub_frag_mem_limit(qp->q.net, head->truesize);
|
|
|
|
*nextp = NULL;
|
|
head->next = NULL;
|
|
head->prev = NULL;
|
|
head->dev = dev;
|
|
head->tstamp = qp->q.stamp;
|
|
IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size);
|
|
|
|
iph = ip_hdr(head);
|
|
iph->tot_len = htons(len);
|
|
iph->tos |= ecn;
|
|
|
|
/* When we set IP_DF on a refragmented skb we must also force a
|
|
* call to ip_fragment to avoid forwarding a DF-skb of size s while
|
|
* original sender only sent fragments of size f (where f < s).
|
|
*
|
|
* We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest
|
|
* frag seen to avoid sending tiny DF-fragments in case skb was built
|
|
* from one very small df-fragment and one large non-df frag.
|
|
*/
|
|
if (qp->max_df_size == qp->q.max_size) {
|
|
IPCB(head)->flags |= IPSKB_FRAG_PMTU;
|
|
iph->frag_off = htons(IP_DF);
|
|
} else {
|
|
iph->frag_off = 0;
|
|
}
|
|
|
|
ip_send_check(iph);
|
|
|
|
__IP_INC_STATS(net, IPSTATS_MIB_REASMOKS);
|
|
qp->q.fragments = NULL;
|
|
qp->q.rb_fragments = RB_ROOT;
|
|
qp->q.fragments_tail = NULL;
|
|
qp->q.last_run_head = NULL;
|
|
return 0;
|
|
|
|
out_nomem:
|
|
net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp);
|
|
err = -ENOMEM;
|
|
goto out_fail;
|
|
out_oversize:
|
|
net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->q.key.v4.saddr);
|
|
out_fail:
|
|
__IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
|
|
return err;
|
|
}
|
|
|
|
/* Process an incoming IP datagram fragment. */
|
|
int ip_defrag(struct net *net, struct sk_buff *skb, u32 user)
|
|
{
|
|
struct net_device *dev = skb->dev ? : skb_dst(skb)->dev;
|
|
int vif = l3mdev_master_ifindex_rcu(dev);
|
|
struct ipq *qp;
|
|
|
|
__IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS);
|
|
skb_orphan(skb);
|
|
|
|
/* Lookup (or create) queue header */
|
|
qp = ip_find(net, ip_hdr(skb), user, vif);
|
|
if (qp) {
|
|
int ret;
|
|
|
|
spin_lock(&qp->q.lock);
|
|
|
|
ret = ip_frag_queue(qp, skb);
|
|
|
|
spin_unlock(&qp->q.lock);
|
|
ipq_put(qp);
|
|
return ret;
|
|
}
|
|
|
|
__IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
|
|
kfree_skb(skb);
|
|
return -ENOMEM;
|
|
}
|
|
EXPORT_SYMBOL(ip_defrag);
|
|
|
|
struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
|
|
{
|
|
struct iphdr iph;
|
|
int netoff;
|
|
u32 len;
|
|
|
|
if (skb->protocol != htons(ETH_P_IP))
|
|
return skb;
|
|
|
|
netoff = skb_network_offset(skb);
|
|
|
|
if (skb_copy_bits(skb, netoff, &iph, sizeof(iph)) < 0)
|
|
return skb;
|
|
|
|
if (iph.ihl < 5 || iph.version != 4)
|
|
return skb;
|
|
|
|
len = ntohs(iph.tot_len);
|
|
if (skb->len < netoff + len || len < (iph.ihl * 4))
|
|
return skb;
|
|
|
|
if (ip_is_fragment(&iph)) {
|
|
skb = skb_share_check(skb, GFP_ATOMIC);
|
|
if (skb) {
|
|
if (!pskb_may_pull(skb, netoff + iph.ihl * 4))
|
|
return skb;
|
|
if (pskb_trim_rcsum(skb, netoff + len))
|
|
return skb;
|
|
memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
|
|
if (ip_defrag(net, skb, user))
|
|
return NULL;
|
|
skb_clear_hash(skb);
|
|
}
|
|
}
|
|
return skb;
|
|
}
|
|
EXPORT_SYMBOL(ip_check_defrag);
|
|
|
|
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);
|
|
|
|
#ifdef CONFIG_SYSCTL
|
|
static int dist_min;
|
|
|
|
static struct ctl_table ip4_frags_ns_ctl_table[] = {
|
|
{
|
|
.procname = "ipfrag_high_thresh",
|
|
.data = &init_net.ipv4.frags.high_thresh,
|
|
.maxlen = sizeof(unsigned long),
|
|
.mode = 0644,
|
|
.proc_handler = proc_doulongvec_minmax,
|
|
.extra1 = &init_net.ipv4.frags.low_thresh
|
|
},
|
|
{
|
|
.procname = "ipfrag_low_thresh",
|
|
.data = &init_net.ipv4.frags.low_thresh,
|
|
.maxlen = sizeof(unsigned long),
|
|
.mode = 0644,
|
|
.proc_handler = proc_doulongvec_minmax,
|
|
.extra2 = &init_net.ipv4.frags.high_thresh
|
|
},
|
|
{
|
|
.procname = "ipfrag_time",
|
|
.data = &init_net.ipv4.frags.timeout,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_jiffies,
|
|
},
|
|
{
|
|
.procname = "ipfrag_max_dist",
|
|
.data = &init_net.ipv4.frags.max_dist,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &dist_min,
|
|
},
|
|
{ }
|
|
};
|
|
|
|
/* secret interval has been deprecated */
|
|
static int ip4_frags_secret_interval_unused;
|
|
static struct ctl_table ip4_frags_ctl_table[] = {
|
|
{
|
|
.procname = "ipfrag_secret_interval",
|
|
.data = &ip4_frags_secret_interval_unused,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_jiffies,
|
|
},
|
|
{ }
|
|
};
|
|
|
|
static int __net_init ip4_frags_ns_ctl_register(struct net *net)
|
|
{
|
|
struct ctl_table *table;
|
|
struct ctl_table_header *hdr;
|
|
|
|
table = ip4_frags_ns_ctl_table;
|
|
if (!net_eq(net, &init_net)) {
|
|
table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL);
|
|
if (!table)
|
|
goto err_alloc;
|
|
|
|
table[0].data = &net->ipv4.frags.high_thresh;
|
|
table[0].extra1 = &net->ipv4.frags.low_thresh;
|
|
table[0].extra2 = &init_net.ipv4.frags.high_thresh;
|
|
table[1].data = &net->ipv4.frags.low_thresh;
|
|
table[1].extra2 = &net->ipv4.frags.high_thresh;
|
|
table[2].data = &net->ipv4.frags.timeout;
|
|
table[3].data = &net->ipv4.frags.max_dist;
|
|
}
|
|
|
|
hdr = register_net_sysctl(net, "net/ipv4", table);
|
|
if (!hdr)
|
|
goto err_reg;
|
|
|
|
net->ipv4.frags_hdr = hdr;
|
|
return 0;
|
|
|
|
err_reg:
|
|
if (!net_eq(net, &init_net))
|
|
kfree(table);
|
|
err_alloc:
|
|
return -ENOMEM;
|
|
}
|
|
|
|
static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
|
|
{
|
|
struct ctl_table *table;
|
|
|
|
table = net->ipv4.frags_hdr->ctl_table_arg;
|
|
unregister_net_sysctl_table(net->ipv4.frags_hdr);
|
|
kfree(table);
|
|
}
|
|
|
|
static void __init ip4_frags_ctl_register(void)
|
|
{
|
|
register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table);
|
|
}
|
|
#else
|
|
static int ip4_frags_ns_ctl_register(struct net *net)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static void ip4_frags_ns_ctl_unregister(struct net *net)
|
|
{
|
|
}
|
|
|
|
static void __init ip4_frags_ctl_register(void)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static int __net_init ipv4_frags_init_net(struct net *net)
|
|
{
|
|
int res;
|
|
|
|
/* Fragment cache limits.
|
|
*
|
|
* The fragment memory accounting code, (tries to) account for
|
|
* the real memory usage, by measuring both the size of frag
|
|
* queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue))
|
|
* and the SKB's truesize.
|
|
*
|
|
* A 64K fragment consumes 129736 bytes (44*2944)+200
|
|
* (1500 truesize == 2944, sizeof(struct ipq) == 200)
|
|
*
|
|
* We will commit 4MB at one time. Should we cross that limit
|
|
* we will prune down to 3MB, making room for approx 8 big 64K
|
|
* fragments 8x128k.
|
|
*/
|
|
net->ipv4.frags.high_thresh = 4 * 1024 * 1024;
|
|
net->ipv4.frags.low_thresh = 3 * 1024 * 1024;
|
|
/*
|
|
* Important NOTE! Fragment queue must be destroyed before MSL expires.
|
|
* RFC791 is wrong proposing to prolongate timer each fragment arrival
|
|
* by TTL.
|
|
*/
|
|
net->ipv4.frags.timeout = IP_FRAG_TIME;
|
|
|
|
net->ipv4.frags.max_dist = 64;
|
|
net->ipv4.frags.f = &ip4_frags;
|
|
|
|
res = inet_frags_init_net(&net->ipv4.frags);
|
|
if (res < 0)
|
|
return res;
|
|
res = ip4_frags_ns_ctl_register(net);
|
|
if (res < 0)
|
|
inet_frags_exit_net(&net->ipv4.frags);
|
|
return res;
|
|
}
|
|
|
|
static void __net_exit ipv4_frags_exit_net(struct net *net)
|
|
{
|
|
ip4_frags_ns_ctl_unregister(net);
|
|
inet_frags_exit_net(&net->ipv4.frags);
|
|
}
|
|
|
|
static struct pernet_operations ip4_frags_ops = {
|
|
.init = ipv4_frags_init_net,
|
|
.exit = ipv4_frags_exit_net,
|
|
};
|
|
|
|
|
|
static u32 ip4_key_hashfn(const void *data, u32 len, u32 seed)
|
|
{
|
|
return jhash2(data,
|
|
sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
|
|
}
|
|
|
|
static u32 ip4_obj_hashfn(const void *data, u32 len, u32 seed)
|
|
{
|
|
const struct inet_frag_queue *fq = data;
|
|
|
|
return jhash2((const u32 *)&fq->key.v4,
|
|
sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
|
|
}
|
|
|
|
static int ip4_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
|
|
{
|
|
const struct frag_v4_compare_key *key = arg->key;
|
|
const struct inet_frag_queue *fq = ptr;
|
|
|
|
return !!memcmp(&fq->key, key, sizeof(*key));
|
|
}
|
|
|
|
static const struct rhashtable_params ip4_rhash_params = {
|
|
.head_offset = offsetof(struct inet_frag_queue, node),
|
|
.key_offset = offsetof(struct inet_frag_queue, key),
|
|
.key_len = sizeof(struct frag_v4_compare_key),
|
|
.hashfn = ip4_key_hashfn,
|
|
.obj_hashfn = ip4_obj_hashfn,
|
|
.obj_cmpfn = ip4_obj_cmpfn,
|
|
.automatic_shrinking = true,
|
|
};
|
|
|
|
void __init ipfrag_init(void)
|
|
{
|
|
ip4_frags.constructor = ip4_frag_init;
|
|
ip4_frags.destructor = ip4_frag_free;
|
|
ip4_frags.qsize = sizeof(struct ipq);
|
|
ip4_frags.frag_expire = ip_expire;
|
|
ip4_frags.frags_cache_name = ip_frag_cache_name;
|
|
ip4_frags.rhash_params = ip4_rhash_params;
|
|
if (inet_frags_init(&ip4_frags))
|
|
panic("IP: failed to allocate ip4_frags cache\n");
|
|
ip4_frags_ctl_register();
|
|
register_pernet_subsys(&ip4_frags_ops);
|
|
}
|