kernel.git/net/ipv4/ip_output.c, branch linux-3.16.y

inet: protect against too small mtu values.

2020-02-11T20:03:57Z

commit 501a90c945103e8627406763dac418f20f3837b2 upstream. syzbot was once again able to crash a host by setting a very small mtu on loopback device. Let's make inetdev_valid_mtu() available in include/net/ip.h, and use it in ip_setup_cork(), so that we protect both ip_append_page() and __ip_append_data() Also add a READ_ONCE() when the device mtu is read. Pairs this lockless read with one WRITE_ONCE() in __dev_set_mtu(), even if other code paths might write over this field. Add a big comment in include/linux/netdevice.h about dev->mtu needing READ_ONCE()/WRITE_ONCE() annotations. Hopefully we will add the missing ones in followup patches. [1] refcount_t: saturated; leaking memory. WARNING: CPU: 0 PID: 9464 at lib/refcount.c:22 refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 9464 Comm: syz-executor850 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 panic+0x2e3/0x75c kernel/panic.c:221 __warn.cold+0x2f/0x3e kernel/panic.c:582 report_bug+0x289/0x300 lib/bug.c:195 fixup_bug arch/x86/kernel/traps.c:174 [inline] fixup_bug arch/x86/kernel/traps.c:169 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 RIP: 0010:refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22 Code: 06 31 ff 89 de e8 c8 f5 e6 fd 84 db 0f 85 6f ff ff ff e8 7b f4 e6 fd 48 c7 c7 e0 71 4f 88 c6 05 56 a6 a4 06 01 e8 c7 a8 b7 fd <0f> 0b e9 50 ff ff ff e8 5c f4 e6 fd 0f b6 1d 3d a6 a4 06 31 ff 89 RSP: 0018:ffff88809689f550 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815e4336 RDI: ffffed1012d13e9c RBP: ffff88809689f560 R08: ffff88809c50a3c0 R09: fffffbfff15d31b1 R10: fffffbfff15d31b0 R11: ffffffff8ae98d87 R12: 0000000000000001 R13: 0000000000040100 R14: ffff888099041104 R15: ffff888218d96e40 refcount_add include/linux/refcount.h:193 [inline] skb_set_owner_w+0x2b6/0x410 net/core/sock.c:1999 sock_wmalloc+0xf1/0x120 net/core/sock.c:2096 ip_append_page+0x7ef/0x1190 net/ipv4/ip_output.c:1383 udp_sendpage+0x1c7/0x480 net/ipv4/udp.c:1276 inet_sendpage+0xdb/0x150 net/ipv4/af_inet.c:821 kernel_sendpage+0x92/0xf0 net/socket.c:3794 sock_sendpage+0x8b/0xc0 net/socket.c:936 pipe_to_sendpage+0x2da/0x3c0 fs/splice.c:458 splice_from_pipe_feed fs/splice.c:512 [inline] __splice_from_pipe+0x3ee/0x7c0 fs/splice.c:636 splice_from_pipe+0x108/0x170 fs/splice.c:671 generic_splice_sendpage+0x3c/0x50 fs/splice.c:842 do_splice_from fs/splice.c:861 [inline] direct_splice_actor+0x123/0x190 fs/splice.c:1035 splice_direct_to_actor+0x3b4/0xa30 fs/splice.c:990 do_splice_direct+0x1da/0x2a0 fs/splice.c:1078 do_sendfile+0x597/0xd00 fs/read_write.c:1464 __do_sys_sendfile64 fs/read_write.c:1525 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x441409 Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fffb64c4f78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441409 RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005 RBP: 0000000000073b8a R08: 0000000000000010 R09: 0000000000000010 R10: 0000000000010001 R11: 0000000000000246 R12: 0000000000402180 R13: 0000000000402210 R14: 0000000000000000 R15: 0000000000000000 Kernel Offset: disabled Rebooting in 86400 seconds.. Fixes: 1470ddf7f8ce ("inet: Remove explicit write references to sk/inet in ip_append_data") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: - Use ACCESS_ONCE() instead of {READ,WRITE}_ONCE() - Keep using literal 68 instead of IPV4_MIN_MTU - Adjust context] Signed-off-by: Ben Hutchings

ipv4: hash net ptr into fragmentation bucket selection

2019-08-13T11:39:30Z

commit b6a7719aedd7e5c0f2df7641aa47386111682df4 upstream. As namespaces are sometimes used with overlapping ip address ranges, we should also use the namespace as input to the hash to select the ip fragmentation counter bucket. Cc: Eric Dumazet Cc: Flavio Leitner Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings

net: test tailroom before appending to linear skb

2018-10-21T07:46:13Z

commit 113f99c3358564a0647d444c2ae34e8b1abfd5b9 upstream. Device features may change during transmission. In particular with corking, a device may toggle scatter-gather in between allocating and writing to an skb. Do not unconditionally assume that !NETIF_F_SG at write time implies that the same held at alloc time and thus the skb has sufficient tailroom. This issue predates git history. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Eric Dumazet Signed-off-by: Willem de Bruijn Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings

net: reflect mark on tcp syn ack packets

2017-10-12T14:28:01Z

commit e05a90ec9e1680952454ea9510da9a761a5baac9 upstream. SYN-ACK responses on a server in response to a SYN from a client did not get the injected skb mark that was tagged on the SYN packet. Fixes: 84f39b08d786 ("net: support marking accepting TCP sockets") Reviewed-by: Lorenzo Colitti Signed-off-by: Jamal Hadi Salim Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings

net: account for current skb length when deciding about UFO

2017-09-15T17:30:15Z

commit a5cb659bbc1c8644efa0c3138a757a1e432a4880 upstream. Our customer encountered stuck NFS writes for blocks starting at specific offsets w.r.t. page boundary caused by networking stack sending packets via UFO enabled device with wrong checksum. The problem can be reproduced by composing a long UDP datagram from multiple parts using MSG_MORE flag: sendto(sd, buff, 1000, MSG_MORE, ...); sendto(sd, buff, 1000, MSG_MORE, ...); sendto(sd, buff, 3000, 0, ...); Assume this packet is to be routed via a device with MTU 1500 and NETIF_F_UFO enabled. When second sendto() gets into __ip_append_data(), this condition is tested (among others) to decide whether to call ip_ufo_append_data(): ((length + fragheaderlen) > mtu) || (skb && skb_is_gso(skb)) At the moment, we already have skb with 1028 bytes of data which is not marked for GSO so that the test is false (fragheaderlen is usually 20). Thus we append second 1000 bytes to this skb without invoking UFO. Third sendto(), however, has sufficient length to trigger the UFO path so that we end up with non-UFO skb followed by a UFO one. Later on, udp_send_skb() uses udp_csum() to calculate the checksum but that assumes all fragments have correct checksum in skb->csum which is not true for UFO fragments. When checking against MTU, we need to add skb->len to length of new segment if we already have a partially filled skb and fragheaderlen only if there isn't one. In the IPv6 case, skb can only be null if this is the first segment so that we have to use headersize (length of the first IPv6 header) rather than fragheaderlen (length of IPv6 header of further fragments) for skb == NULL. Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach") Fixes: e4c5e13aa45c ("ipv6: Should use consistent conditional judgement for ip6 fragment between __ip6_append_data and ip6_finish_output") Signed-off-by: Michal Kubecek Acked-by: Vlad Yasevich Signed-off-by: David S. Miller [bwh: Backported to 3.16: - Move headersize out of the if-statement in ip6_append_data() so it can be used for this - Adjust context to apply after "udp: consistently apply ufo or fragmentation"] Signed-off-by: Ben Hutchings

ipv4: Should use consistent conditional judgement for ip fragment in __ip_append_data and ip_finish_output

2017-09-15T17:30:15Z

commit 0a28cfd51e17f4f0a056bcf66bfbe492c3b99f38 upstream. There is an inconsistent conditional judgement in __ip_append_data and ip_finish_output functions, the variable length in __ip_append_data just include the length of application's payload and udp header, don't include the length of ip header, but in ip_finish_output use (skb->len > ip_skb_dst_mtu(skb)) as judgement, and skb->len include the length of ip header. That causes some particular application's udp payload whose length is between (MTU - IP Header) and MTU were fragmented by ip_fragment even though the rst->dev support UFO feature. Add the length of ip header to length in __ip_append_data to keep consistent conditional judgement as ip_finish_output for ip fragment. Signed-off-by: Zheng Li Signed-off-by: David S. Miller [bwh: Backported to 3.16: adjust context to apply after "udp: consistently apply ufo or fragmentation"] Signed-off-by: Ben Hutchings

udp: consistently apply ufo or fragmentation

2017-08-26T01:14:49Z

commit 85f1bd9a7b5a79d5baa8bf44af19658f7bf77bfa upstream. When iteratively building a UDP datagram with MSG_MORE and that datagram exceeds MTU, consistently choose UFO or fragmentation. Once skb_is_gso, always apply ufo. Conversely, once a datagram is split across multiple skbs, do not consider ufo. Sendpage already maintains the first invariant, only add the second. IPv6 does not have a sendpage implementation to modify. A gso skb must have a partial checksum, do not follow sk_no_check_tx in udp_send_skb. Found by syzkaller. Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach") Reported-by: Andrey Konovalov Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: - ip6_append_data() doesn't take a queue parameter; use &sk->sk_write_queue - Adjust context] Signed-off-by: Ben Hutchings

udp: avoid ufo handling on IP payload compression packets

2017-07-18T17:40:10Z

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 3.16: adjust context] Signed-off-by: Ben Hutchings

ipv4: Set skb->protocol properly for local output

2017-02-23T03:54:41Z

commit f4180439109aa720774baafdd798b3234ab1a0d2 upstream. When xfrm is applied to TSO/GSO packets, it follows this path: xfrm_output() -> xfrm_output_gso() -> skb_gso_segment() where skb_gso_segment() relies on skb->protocol to function properly. This patch sets skb->protocol to ETH_P_IP before dst_output() is called, fixing a bug where GSO packets sent through a sit tunnel are dropped when xfrm is involved. Signed-off-by: Eli Cooper Signed-off-by: David S. Miller [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings

ipv4: allow local fragmentation in ip_finish_output_gso()

2017-02-23T03:54:29Z

commit 9ee6c5dc816aa8256257f2cd4008a9291ec7e985 upstream. Some configurations (e.g. geneve interface with default MTU of 1500 over an ethernet interface with 1500 MTU) result in the transmission of packets that exceed the configured MTU. While this should be considered to be a "bad" configuration, it is still allowed and should not result in the sending of packets that exceed the configured MTU. Fix by dropping the assumption in ip_finish_output_gso() that locally originated gso packets will never need fragmentation. Basic testing using iperf (observing CPU usage and bandwidth) have shown no measurable performance impact for traffic not requiring fragmentation. Fixes: c7ba65d7b649 ("net: ip: push gso skb forwarding handling down the stack") Reported-by: Jan Tluka Signed-off-by: Lance Richardson Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller [bwh: Backported to 3.16: never had the IPSKB_FRAG_SEGS flag] Signed-off-by: Ben Hutchings