linux-stable.git/net/ipv6/ip6_output.c, branch linux-3.2.y

ipv6: accept 64k - 1 packet length in ip6_find_1stfragopt()

2017-11-11T13:34:30+00:00

commit 3de33e1ba0506723ab25734e098cf280ecc34756 upstream.

A packet length of exactly IPV6_MAXPLEN is allowed, we should
refuse parsing options only if the size is 64KiB or more.

While at it, remove one extra variable and one assignment which
were also introduced by the commit that introduced the size
check. Checking the sum 'offset + len' and only later adding
'len' to 'offset' doesn't provide any advantage over directly
summing to 'offset' and checking it.

Fixes: 6399f1fae4ec ("ipv6: avoid overflow of offset in ip6_find_1stfragopt")
Signed-off-by: Stefano Brivio 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings

ipv6: avoid overflow of offset in ip6_find_1stfragopt

2017-08-26T01:14:05+00:00

commit 6399f1fae4ec29fab5ec76070435555e256ca3a6 upstream.

In some cases, offset can overflow and can cause an infinite loop in
ip6_find_1stfragopt(). Make it unsigned int to prevent the overflow, and
cap it at IPV6_MAXPLEN, since packets larger than that should be invalid.

This problem has been here since before the beginning of git history.

Signed-off-by: Sabrina Dubroca 
Acked-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings

udp: avoid ufo handling on IP payload compression packets

2017-07-18T17:38:31+00:00

commit 4b3b45edba9222e518a1ec72df841eba3609fe34 upstream.

commit c146066ab802 ("ipv4: Don't use ufo handling on later transformed
packets") and commit f89c56ce710a ("ipv6: Don't use ufo handling on
later transformed packets") added a check that 'rt->dst.header_len' isn't
zero in order to skip UFO, but it doesn't include IPcomp in transport mode
where it equals zero.

Packets, after payload compression, may not require further fragmentation,
and if original length exceeds MTU, later compressed packets will be
transmitted incorrectly. This can be reproduced with LTP udp_ipsec.sh test
on veth device with enabled UFO, MTU is 1500 and UDP payload is 2000:

* IPv4 case, offset is wrong + unnecessary fragmentation
    udp_ipsec.sh -p comp -m transport -s 2000 &
    tcpdump -ni ltp_ns_veth2
    ...
    IP (tos 0x0, ttl 64, id 45203, offset 0, flags [+],
      proto Compressed IP (108), length 49)
      10.0.0.2 > 10.0.0.1: IPComp(cpi=0x1000)
    IP (tos 0x0, ttl 64, id 45203, offset 1480, flags [none],
      proto UDP (17), length 21) 10.0.0.2 > 10.0.0.1: ip-proto-17

* IPv6 case, sending small fragments
    udp_ipsec.sh -6 -p comp -m transport -s 2000 &
    tcpdump -ni ltp_ns_veth2
    ...
    IP6 (flowlabel 0x6b9ba, hlim 64, next-header Compressed IP (108)
      payload length: 37) fd00::2 > fd00::1: IPComp(cpi=0x1000)
    IP6 (flowlabel 0x6b9ba, hlim 64, next-header Compressed IP (108)
      payload length: 21) fd00::2 > fd00::1: IPComp(cpi=0x1000)

Fix it by checking 'rt->dst.xfrm' pointer to 'xfrm_state' struct, skip UFO
if xfrm is set. So the new check will include both cases: IPcomp and IPsec.

Fixes: c146066ab802 ("ipv4: Don't use ufo handling on later transformed packets")
Fixes: f89c56ce710a ("ipv6: Don't use ufo handling on later transformed packets")
Signed-off-by: Alexey Kodanev 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

ipv6: fix out of bound writes in __ip6_append_data()

2017-06-05T20:13:57+00:00

commit 232cd35d0804cc241eb887bb8d4d9b3b9881c64a upstream.

Andrey Konovalov and idaifish@gmail.com reported crashes caused by
one skb shared_info being overwritten from __ip6_append_data()

Andrey program lead to following state :

copy -4200 datalen 2000 fraglen 2040
maxfraglen 2040 alloclen 2048 transhdrlen 0 offset 0 fraggap 6200

The skb_copy_and_csum_bits(skb_prev, maxfraglen, data + transhdrlen,
fraggap, 0); is overwriting skb->head and skb_shared_info

Since we apparently detect this rare condition too late, move the
code earlier to even avoid allocating skb and risking crashes.

Once again, many thanks to Andrey and syzkaller team.

Signed-off-by: Eric Dumazet 
Reported-by: Andrey Konovalov 
Tested-by: Andrey Konovalov 
Reported-by: 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

ipv6: Check ip6_find_1stfragopt() return value properly.

2017-06-05T20:13:57+00:00

commit 7dd7eb9513bd02184d45f000ab69d78cb1fa1531 upstream.

Do not use unsigned variables to see if it returns a negative
error or not.

Fixes: 2423496af35d ("ipv6: Prevent overrun when parsing v6 header options")
Reported-by: Julia Lawall 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2: adjust filenames, context]
Signed-off-by: Ben Hutchings

ipv6: Prevent overrun when parsing v6 header options

2017-06-05T20:13:57+00:00

commit 2423496af35d94a87156b063ea5cedffc10a70a1 upstream.

The KASAN warning repoted below was discovered with a syzkaller
program.  The reproducer is basically:
  int s = socket(AF_INET6, SOCK_RAW, NEXTHDR_HOP);
  send(s, &one_byte_of_data, 1, MSG_MORE);
  send(s, &more_than_mtu_bytes_data, 2000, 0);

The socket() call sets the nexthdr field of the v6 header to
NEXTHDR_HOP, the first send call primes the payload with a non zero
byte of data, and the second send call triggers the fragmentation path.

The fragmentation code tries to parse the header options in order
to figure out where to insert the fragment option.  Since nexthdr points
to an invalid option, the calculation of the size of the network header
can made to be much larger than the linear section of the skb and data
is read outside of it.

This fix makes ip6_find_1stfrag return an error if it detects
running out-of-bounds.

[   42.361487] ==================================================================
[   42.364412] BUG: KASAN: slab-out-of-bounds in ip6_fragment+0x11c8/0x3730
[   42.365471] Read of size 840 at addr ffff88000969e798 by task ip6_fragment-oo/3789
[   42.366469]
[   42.366696] CPU: 1 PID: 3789 Comm: ip6_fragment-oo Not tainted 4.11.0+ #41
[   42.367628] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1ubuntu1 04/01/2014
[   42.368824] Call Trace:
[   42.369183]  dump_stack+0xb3/0x10b
[   42.369664]  print_address_description+0x73/0x290
[   42.370325]  kasan_report+0x252/0x370
[   42.370839]  ? ip6_fragment+0x11c8/0x3730
[   42.371396]  check_memory_region+0x13c/0x1a0
[   42.371978]  memcpy+0x23/0x50
[   42.372395]  ip6_fragment+0x11c8/0x3730
[   42.372920]  ? nf_ct_expect_unregister_notifier+0x110/0x110
[   42.373681]  ? ip6_copy_metadata+0x7f0/0x7f0
[   42.374263]  ? ip6_forward+0x2e30/0x2e30
[   42.374803]  ip6_finish_output+0x584/0x990
[   42.375350]  ip6_output+0x1b7/0x690
[   42.375836]  ? ip6_finish_output+0x990/0x990
[   42.376411]  ? ip6_fragment+0x3730/0x3730
[   42.376968]  ip6_local_out+0x95/0x160
[   42.377471]  ip6_send_skb+0xa1/0x330
[   42.377969]  ip6_push_pending_frames+0xb3/0xe0
[   42.378589]  rawv6_sendmsg+0x2051/0x2db0
[   42.379129]  ? rawv6_bind+0x8b0/0x8b0
[   42.379633]  ? _copy_from_user+0x84/0xe0
[   42.380193]  ? debug_check_no_locks_freed+0x290/0x290
[   42.380878]  ? ___sys_sendmsg+0x162/0x930
[   42.381427]  ? rcu_read_lock_sched_held+0xa3/0x120
[   42.382074]  ? sock_has_perm+0x1f6/0x290
[   42.382614]  ? ___sys_sendmsg+0x167/0x930
[   42.383173]  ? lock_downgrade+0x660/0x660
[   42.383727]  inet_sendmsg+0x123/0x500
[   42.384226]  ? inet_sendmsg+0x123/0x500
[   42.384748]  ? inet_recvmsg+0x540/0x540
[   42.385263]  sock_sendmsg+0xca/0x110
[   42.385758]  SYSC_sendto+0x217/0x380
[   42.386249]  ? SYSC_connect+0x310/0x310
[   42.386783]  ? __might_fault+0x110/0x1d0
[   42.387324]  ? lock_downgrade+0x660/0x660
[   42.387880]  ? __fget_light+0xa1/0x1f0
[   42.388403]  ? __fdget+0x18/0x20
[   42.388851]  ? sock_common_setsockopt+0x95/0xd0
[   42.389472]  ? SyS_setsockopt+0x17f/0x260
[   42.390021]  ? entry_SYSCALL_64_fastpath+0x5/0xbe
[   42.390650]  SyS_sendto+0x40/0x50
[   42.391103]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[   42.391731] RIP: 0033:0x7fbbb711e383
[   42.392217] RSP: 002b:00007ffff4d34f28 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
[   42.393235] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbbb711e383
[   42.394195] RDX: 0000000000001000 RSI: 00007ffff4d34f60 RDI: 0000000000000003
[   42.395145] RBP: 0000000000000046 R08: 00007ffff4d34f40 R09: 0000000000000018
[   42.396056] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400aad
[   42.396598] R13: 0000000000000066 R14: 00007ffff4d34ee0 R15: 00007fbbb717af00
[   42.397257]
[   42.397411] Allocated by task 3789:
[   42.397702]  save_stack_trace+0x16/0x20
[   42.398005]  save_stack+0x46/0xd0
[   42.398267]  kasan_kmalloc+0xad/0xe0
[   42.398548]  kasan_slab_alloc+0x12/0x20
[   42.398848]  __kmalloc_node_track_caller+0xcb/0x380
[   42.399224]  __kmalloc_reserve.isra.32+0x41/0xe0
[   42.399654]  __alloc_skb+0xf8/0x580
[   42.400003]  sock_wmalloc+0xab/0xf0
[   42.400346]  __ip6_append_data.isra.41+0x2472/0x33d0
[   42.400813]  ip6_append_data+0x1a8/0x2f0
[   42.401122]  rawv6_sendmsg+0x11ee/0x2db0
[   42.401505]  inet_sendmsg+0x123/0x500
[   42.401860]  sock_sendmsg+0xca/0x110
[   42.402209]  ___sys_sendmsg+0x7cb/0x930
[   42.402582]  __sys_sendmsg+0xd9/0x190
[   42.402941]  SyS_sendmsg+0x2d/0x50
[   42.403273]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[   42.403718]
[   42.403871] Freed by task 1794:
[   42.404146]  save_stack_trace+0x16/0x20
[   42.404515]  save_stack+0x46/0xd0
[   42.404827]  kasan_slab_free+0x72/0xc0
[   42.405167]  kfree+0xe8/0x2b0
[   42.405462]  skb_free_head+0x74/0xb0
[   42.405806]  skb_release_data+0x30e/0x3a0
[   42.406198]  skb_release_all+0x4a/0x60
[   42.406563]  consume_skb+0x113/0x2e0
[   42.406910]  skb_free_datagram+0x1a/0xe0
[   42.407288]  netlink_recvmsg+0x60d/0xe40
[   42.407667]  sock_recvmsg+0xd7/0x110
[   42.408022]  ___sys_recvmsg+0x25c/0x580
[   42.408395]  __sys_recvmsg+0xd6/0x190
[   42.408753]  SyS_recvmsg+0x2d/0x50
[   42.409086]  entry_SYSCALL_64_fastpath+0x1f/0xbe
[   42.409513]
[   42.409665] The buggy address belongs to the object at ffff88000969e780
[   42.409665]  which belongs to the cache kmalloc-512 of size 512
[   42.410846] The buggy address is located 24 bytes inside of
[   42.410846]  512-byte region [ffff88000969e780, ffff88000969e980)
[   42.411941] The buggy address belongs to the page:
[   42.412405] page:ffffea000025a780 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
[   42.413298] flags: 0x100000000008100(slab|head)
[   42.413729] raw: 0100000000008100 0000000000000000 0000000000000000 00000001800c000c
[   42.414387] raw: ffffea00002a9500 0000000900000007 ffff88000c401280 0000000000000000
[   42.415074] page dumped because: kasan: bad access detected
[   42.415604]
[   42.415757] Memory state around the buggy address:
[   42.416222]  ffff88000969e880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   42.416904]  ffff88000969e900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   42.417591] >ffff88000969e980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[   42.418273]                    ^
[   42.418588]  ffff88000969ea00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   42.419273]  ffff88000969ea80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   42.419882] ==================================================================

Reported-by: Andrey Konovalov 
Signed-off-by: Craig Gallek 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2: adjust filenames, context]
Signed-off-by: Ben Hutchings

ipv6: Don't use ufo handling on later transformed packets

2017-02-23T03:50:57+00:00

commit f89c56ce710afa65e1b2ead555b52c4807f34ff7 upstream.

Similar to commit c146066ab802 ("ipv4: Don't use ufo handling on later
transformed packets"), don't perform UFO on packets that will be IPsec
transformed. To detect it we rely on the fact that headerlen in
dst_entry is non-zero only for transformation bundles (xfrm_dst
objects).

Unwanted segmentation can be observed with a NETIF_F_UFO capable device,
such as a dummy device:

  DEV=dum0 LEN=1493

  ip li add $DEV type dummy
  ip addr add fc00::1/64 dev $DEV nodad
  ip link set $DEV up
  ip xfrm policy add dir out src fc00::1 dst fc00::2 \
     tmpl src fc00::1 dst fc00::2 proto esp spi 1
  ip xfrm state add src fc00::1 dst fc00::2 \
     proto esp spi 1 enc 'aes' 0x0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b

  tcpdump -n -nn -i $DEV -t &
  socat /dev/zero,readbytes=$LEN udp6:[fc00::2]:$LEN

tcpdump output before:

  IP6 fc00::1 > fc00::2: frag (0|1448) ESP(spi=0x00000001,seq=0x1), length 1448
  IP6 fc00::1 > fc00::2: frag (1448|48)
  IP6 fc00::1 > fc00::2: ESP(spi=0x00000001,seq=0x2), length 88

... and after:

  IP6 fc00::1 > fc00::2: frag (0|1448) ESP(spi=0x00000001,seq=0x1), length 1448
  IP6 fc00::1 > fc00::2: frag (1448|80)

Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach")

Signed-off-by: Jakub Sitnicki 
Acked-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

ipv6: Count in extension headers in skb->network_header

2016-04-30T22:05:27+00:00

[ Upstream commit 3ba3458fb9c050718b95275a3310b74415e767e2 ]

When sending a UDPv6 message longer than MTU, account for the length
of fragmentable IPv6 extension headers in skb->network_header offset.
Same as we do in alloc_new_skb path in __ip6_append_data().

This ensures that later on __ip6_make_skb() will make space in
headroom for fragmentable extension headers:

	/* move skb->data to ip header from ext header */
	if (skb->data < skb_network_header(skb))
		__skb_pull(skb, skb_network_offset(skb));

Prevents a splat due to skb_under_panic:

skbuff: skb_under_panic: text:ffffffff8143397b len:2126 put:14 \
head:ffff880005bacf50 data:ffff880005bacf4a tail:0x48 end:0xc0 dev:lo
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:104!
invalid opcode: 0000 [#1] KASAN
CPU: 0 PID: 160 Comm: reproducer Not tainted 4.6.0-rc2 #65
[...]
Call Trace:
 [] skb_push+0x79/0x80
 [] eth_header+0x2b/0x100
 [] neigh_resolve_output+0x210/0x310
 [] ip6_finish_output2+0x4a7/0x7c0
 [] ip6_output+0x16a/0x280
 [] ip6_local_out+0xb1/0xf0
 [] ip6_send_skb+0x45/0xd0
 [] udp_v6_send_skb+0x246/0x5d0
 [] udpv6_sendmsg+0xa6e/0x1090
[...]

Reported-by: Ji Jianwen 
Signed-off-by: Jakub Sitnicki 
Acked-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

udp: only allow UFO for packets from SOCK_DGRAM sockets

2015-05-09T22:16:38+00:00

[ Upstream commit acf8dd0a9d0b9e4cdb597c2f74802f79c699e802 ]

If an over-MTU UDP datagram is sent through a SOCK_RAW socket to a
UFO-capable device, ip_ufo_append_data() sets skb->ip_summed to
CHECKSUM_PARTIAL unconditionally as all GSO code assumes transport layer
checksum is to be computed on segmentation. However, in this case,
skb->csum_start and skb->csum_offset are never set as raw socket
transmit path bypasses udp_send_skb() where they are usually set. As a
result, driver may access invalid memory when trying to calculate the
checksum and store the result (as observed in virtio_net driver).

Moreover, the very idea of modifying the userspace provided UDP header
is IMHO against raw socket semantics (I wasn't able to find a document
clearly stating this or the opposite, though). And while allowing
CHECKSUM_NONE in the UFO case would be more efficient, it would be a bit
too intrusive change just to handle a corner case like this. Therefore
disallowing UFO for packets from SOCK_DGRAM seems to be the best option.

Signed-off-by: Michal Kubecek 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

ipv6: Remove all uses of LL_ALLOCATED_SPACE

2015-02-20T00:49:23+00:00

commit a7ae1992248e5cf9dc5bd35695ab846d27efe15f upstream.

ipv6: Remove all uses of LL_ALLOCATED_SPACE

The macro LL_ALLOCATED_SPACE was ill-conceived.  It applies the
alignment to the sum of needed_headroom and needed_tailroom.  As
the amount that is then reserved for head room is needed_headroom
with alignment, this means that the tail room left may be too small.

This patch replaces all uses of LL_ALLOCATED_SPACE in net/ipv6
with the macro LL_RESERVED_SPACE and direct reference to
needed_tailroom.

This also fixes the problem with needed_headroom changing between
allocating the skb and reserving the head room.

Signed-off-by: Herbert Xu 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings