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: fa0f527358bd ("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>
Roman reports that DHCPv6 client no longer sees replies from server
due to
ip6tables -t raw -A PREROUTING -m rpfilter --invert -j DROP
rule. We need to set the F_IFACE flag for linklocal addresses, they
are scoped per-device.
Fixes: 47b7e7f82802 ("netfilter: don't set F_IFACE on ipv6 fib lookups")
Reported-by: Roman Mamedov <rm@romanrm.net>
Tested-by: Roman Mamedov <rm@romanrm.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
don't bother with pathological cases, they only waste cycles.
IPv6 requires a minimum MTU of 1280 so we should never see fragments
smaller than this (except last frag).
v3: don't use awkward "-offset + len"
v2: drop IPv4 part, which added same check w. IPV4_MIN_MTU (68).
There were concerns that there could be even smaller frags
generated by intermediate nodes, e.g. on radio networks.
Cc: Peter Oskolkov <posk@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Similar to TCP OOO RX queue, it makes sense to use rb trees to store
IP fragments, so that OOO fragments are inserted faster.
Tested:
- a follow-up patch contains a rather comprehensive ip defrag
self-test (functional)
- ran neper `udp_stream -c -H <host> -F 100 -l 300 -T 20`:
netstat --statistics
Ip:
282078937 total packets received
0 forwarded
0 incoming packets discarded
946760 incoming packets delivered
18743456 requests sent out
101 fragments dropped after timeout
282077129 reassemblies required
944952 packets reassembled ok
262734239 packet reassembles failed
(The numbers/stats above are somewhat better re:
reassemblies vs a kernel without this patchset. More
comprehensive performance testing TBD).
Reported-by: Jann Horn <jannh@google.com>
Reported-by: Juha-Matti Tilli <juha-matti.tilli@iki.fi>
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pablo Neira Ayuso says:
====================
Netfilter/IPVS updates for net-next
The following patchset contains Netfilter/IPVS updates for your net-next
tree:
1) No need to set ttl from reject action for the bridge family, from
Taehee Yoo.
2) Use a fixed timeout for flow that are passed up from the flowtable
to conntrack, from Florian Westphal.
3) More preparation patches for tproxy support for nf_tables, from Mate
Eckl.
4) Remove unnecessary indirection in core IPv6 checksum function, from
Florian Westphal.
5) Use nf_ct_get_tuplepr() from openvswitch, instead of opencoding it.
From Florian Westphal.
6) socket match now selects socket infrastructure, instead of depending
on it. From Mate Eckl.
7) Patch series to simplify conntrack tuple building/parsing from packet
path and ctnetlink, from Florian Westphal.
8) Fetch timeout policy from protocol helpers, instead of doing it from
core, from Florian Westphal.
9) Merge IPv4 and IPv6 protocol trackers into conntrack core, from
Florian Westphal.
10) Depend on CONFIG_NF_TABLES_IPV6 and CONFIG_IP6_NF_IPTABLES
respectively, instead of IPV6. Patch from Mate Eckl.
11) Add specific function for garbage collection in conncount,
from Yi-Hung Wei.
12) Catch number of elements in the connlimit list, from Yi-Hung Wei.
13) Move locking to nf_conncount, from Yi-Hung Wei.
14) Series of patches to add lockless tree traversal in nf_conncount,
from Yi-Hung Wei.
15) Resolve clash in matching conntracks when race happens, from
Martynas Pumputis.
16) If connection entry times out, remove template entry from the
ip_vs_conn_tab table to improve behaviour under flood, from
Julian Anastasov.
17) Remove useless parameter from nf_ct_helper_ext_add(), from Gao feng.
18) Call abort from 2-phase commit protocol before requesting modules,
make sure this is done under the mutex, from Florian Westphal.
19) Grab module reference when starting transaction, also from Florian.
20) Dynamically allocate expression info array for pre-parsing, from
Florian.
21) Add per netns mutex for nf_tables, from Florian Westphal.
22) A couple of patches to simplify and refactor nf_osf code to prepare
for nft_osf support.
23) Break evaluation on missing socket, from Mate Eckl.
24) Allow to match socket mark from nft_socket, from Mate Eckl.
25) Remove dependency on nf_defrag_ipv6, now that IPv6 tracker is
built-in into nf_conntrack. From Florian Westphal.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
All conflicts were trivial overlapping changes, so reasonably easy to resolve. Signed-off-by: David S. Miller <davem@davemloft.net>
IPV6=m DEFRAG_IPV6=m CONNTRACK=y yields: net/netfilter/nf_conntrack_proto.o: In function `nf_ct_netns_do_get': net/netfilter/nf_conntrack_proto.c:802: undefined reference to `nf_defrag_ipv6_enable' net/netfilter/nf_conntrack_proto.o:(.rodata+0x640): undefined reference to `nf_conntrack_l4proto_icmpv6' Setting DEFRAG_IPV6=y causes undefined references to ip6_rhash_params ip6_frag_init and ip6_expire_frag_queue so it would be needed to force IPV6=y too. This patch gets rid of the 'followup linker error' by removing the dependency of ipv6.ko symbols from netfilter ipv6 defrag. Shared code is placed into a header, then used from both. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This unifies ipv4 and ipv6 protocol trackers and removes the l3proto abstraction. This gets rid of all l3proto indirect calls and the need to do a lookup on the function to call for l3 demux. It increases module size by only a small amount (12kbyte), so this reduces size because nf_conntrack.ko is useless without either nf_conntrack_ipv4 or nf_conntrack_ipv6 module. before: text data bss dec hex filename 7357 1088 0 8445 20fd nf_conntrack_ipv4.ko 7405 1084 4 8493 212d nf_conntrack_ipv6.ko 72614 13689 236 86539 1520b nf_conntrack.ko 19K nf_conntrack_ipv4.ko 19K nf_conntrack_ipv6.ko 179K nf_conntrack.ko after: text data bss dec hex filename 79277 13937 236 93450 16d0a nf_conntrack.ko 191K nf_conntrack.ko Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Not needed, we can have the l4trackers fetch it themselvs. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Handle it in the core instead. ipv6_skip_exthdr() is built-in even if ipv6 is a module, i.e. this doesn't create an ipv6 dependency. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>