linux/net/ipv4
Jakub Kicinski 27a8caa59b ipv4: fix ip option filtering for locally generated fragments
During IP fragmentation we sanitize IP options. This means overwriting
options which should not be copied with NOPs. Only the first fragment
has the original, full options.

ip_fraglist_prepare() copies the IP header and options from previous
fragment to the next one. Commit 19c3401a91 ("net: ipv4: place control
buffer handling away from fragmentation iterators") moved sanitizing
options before ip_fraglist_prepare() which means options are sanitized
and then overwritten again with the old values.

Fixing this is not enough, however, nor did the sanitization work
prior to aforementioned commit.

ip_options_fragment() (which does the sanitization) uses ipcb->opt.optlen
for the length of the options. ipcb->opt of fragments is not populated
(it's 0), only the head skb has the state properly built. So even when
called at the right time ip_options_fragment() does nothing. This seems
to date back all the way to v2.5.44 when the fast path for pre-fragmented
skbs had been introduced. Prior to that ip_options_build() would have been
called for every fragment (in fact ever since v2.5.44 the fragmentation
handing in ip_options_build() has been dead code, I'll clean it up in
-next).

In the original patch (see Link) caixf mentions fixing the handling
for fragments other than the second one, but I'm not sure how _any_
fragment could have had their options sanitized with the code
as it stood.

Tested with python (MTU on lo lowered to 1000 to force fragmentation):

  import socket
  s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  s.setsockopt(socket.IPPROTO_IP, socket.IP_OPTIONS,
               bytearray([7,4,5,192, 20|0x80,4,1,0]))
  s.sendto(b'1'*2000, ('127.0.0.1', 1234))

Before:

IP (tos 0x0, ttl 64, id 1053, offset 0, flags [+], proto UDP (17), length 996, options (RR [bad length 4] [bad ptr 5] 192.148.4.1,,RA value 256))
    localhost.36500 > localhost.search-agent: UDP, length 2000
IP (tos 0x0, ttl 64, id 1053, offset 968, flags [+], proto UDP (17), length 996, options (RR [bad length 4] [bad ptr 5] 192.148.4.1,,RA value 256))
    localhost > localhost: udp
IP (tos 0x0, ttl 64, id 1053, offset 1936, flags [none], proto UDP (17), length 100, options (RR [bad length 4] [bad ptr 5] 192.148.4.1,,RA value 256))
    localhost > localhost: udp

After:

IP (tos 0x0, ttl 96, id 42549, offset 0, flags [+], proto UDP (17), length 996, options (RR [bad length 4] [bad ptr 5] 192.148.4.1,,RA value 256))
    localhost.51607 > localhost.search-agent: UDP, bad length 2000 > 960
IP (tos 0x0, ttl 96, id 42549, offset 968, flags [+], proto UDP (17), length 996, options (NOP,NOP,NOP,NOP,RA value 256))
    localhost > localhost: udp
IP (tos 0x0, ttl 96, id 42549, offset 1936, flags [none], proto UDP (17), length 100, options (NOP,NOP,NOP,NOP,RA value 256))
    localhost > localhost: udp

RA (20 | 0x80) is now copied as expected, RR (7) is "NOPed out".

Link: https://lore.kernel.org/netdev/20220107080559.122713-1-ooppublic@163.com/
Fixes: 19c3401a91 ("net: ipv4: place control buffer handling away from fragmentation iterators")
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: caixf <ooppublic@163.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-01-24 12:01:11 +00:00
..
bpfilter net: Revert "net: optimize the sockptr_t for unified kernel/user address spaces" 2020-08-10 12:06:44 -07:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-01-09 17:00:17 -08:00
af_inet.c net: bpf: Handle return value of BPF_CGROUP_RUN_PROG_INET{4,6}_POST_BIND() 2022-01-06 17:08:35 -08:00
ah4.c Networking changes for 5.14. 2021-06-30 15:51:09 -07:00
arp.c arp: Remove #ifdef CONFIG_PROC_FS 2021-11-22 14:34:07 +00:00
bpf_tcp_ca.c Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-10 15:56:13 -08:00
cipso_ipv4.c NET: IPV4: fix error "do not initialise globals to 0" 2021-09-19 12:43:56 +01:00
datagram.c net/ipv4/datagram.c: remove superfluous header files from datagram.c 2021-09-29 11:39:33 +01:00
devinet.c ipv4: add net device refcount tracker to struct in_device 2021-12-06 16:05:11 -08:00
esp4_offload.c net: move gro definitions to include/net/gro.h 2021-11-16 13:16:54 +00:00
esp4.c ipsec: Remove unneeded extra variable in esp4 esp_ssg_unref() 2021-07-20 16:14:23 +02:00
fib_frontend.c ipv4: convert fib_num_tclassid_users to atomic_t 2021-12-02 11:56:04 +00:00
fib_lookup.h ipv4: Fix spelling mistakes 2021-06-07 14:08:30 -07:00
fib_notifier.c net: ipv4: remove superfluous header files from fib_notifier.c 2021-09-28 17:32:56 -07:00
fib_rules.c fib: rules: remove duplicated nla policies 2021-12-16 07:18:35 -08:00
fib_semantics.c ipv4: add net_hash_mix() dispersion to fib_info_laddrhash keys 2022-01-19 08:14:40 -08:00
fib_trie.c memcg: enable accounting for IP address and routing-related objects 2021-07-20 06:00:38 -07:00
fou.c gro: remove rcu_read_lock/rcu_read_unlock from gro_complete handlers 2021-11-24 17:21:42 -08:00
gre_demux.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
gre_offload.c gro: remove rcu_read_lock/rcu_read_unlock from gro_complete handlers 2021-11-24 17:21:42 -08:00
icmp.c icmp: fix icmp_ext_echo_iio parsing in icmp_build_probe 2021-10-14 07:54:47 -07:00
igmp.c ipv4: drop unused assignment 2021-11-14 12:20:44 +00:00
inet_connection_sock.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-12-09 13:23:02 -08:00
inet_diag.c inet_diag: fix kernel-infoleak for UDP sockets 2021-12-10 21:14:49 -08:00
inet_fragment.c inet: frags: annotate races around fqdir->dead and fqdir->high_thresh 2022-01-13 13:06:05 +00:00
inet_hashtables.c bpf: Add ingress_ifindex to bpf_sk_lookup 2021-11-10 16:29:58 -08:00
inet_timewait_sock.c net: Use generic ns_common::count 2020-08-19 14:06:36 +02:00
inetpeer.c inetpeer: use div64_ul() and clamp_val() calculate inet_peer_threshold 2021-03-01 13:32:12 -08:00
ip_forward.c
ip_fragment.c inet: frags: annotate races around fqdir->dead and fqdir->high_thresh 2022-01-13 13:06:05 +00:00
ip_gre.c gre: Don't accidentally set RTO_ONLINK in gre_fill_metadata_dst() 2022-01-11 20:36:08 -08:00
ip_input.c net: use indirect call helpers for dst_input 2021-02-03 14:51:39 -08:00
ip_options.c net: clean up codestyle for net/ipv4 2020-08-25 06:28:02 -07:00
ip_output.c ipv4: fix ip option filtering for locally generated fragments 2022-01-24 12:01:11 +00:00
ip_sockglue.c ipv4: Exposing __ip_sock_set_tos() in ip.h 2021-11-20 14:11:00 +00:00
ip_tunnel_core.c net: ip_tunnel: clean up endianness conversions 2021-01-08 19:25:35 -08:00
ip_tunnel.c ip: use dev_addr_set() in tunnels 2021-10-13 09:41:37 -07:00
ip_vti.c ip: use dev_addr_set() in tunnels 2021-10-13 09:41:37 -07:00
ipcomp.c Networking changes for 5.14. 2021-06-30 15:51:09 -07:00
ipconfig.c net: ipconfig: Release the rtnl_lock while waiting for carrier 2021-10-28 14:36:41 +01:00
ipip.c ip: use dev_addr_set() in tunnels 2021-10-13 09:41:37 -07:00
ipmr_base.c
ipmr.c fib: rules: remove duplicated nla policies 2021-12-16 07:18:35 -08:00
Kconfig net: ipv4: remove duplicate "the the" phrase in Kconfig text 2020-08-18 16:02:16 -07:00
Makefile bpf: Clean up sockmap related Kconfigs 2021-02-26 12:28:03 -08:00
metrics.c treewide: rename nla_strlcpy to nla_strscpy. 2020-11-16 08:08:54 -08:00
netfilter.c netfilter: Dissect flow after packet mangling 2021-04-18 22:04:16 +02:00
netlink.c
nexthop.c net: Don't include filter.h from net/sock.h 2021-12-29 08:48:14 -08:00
ping.c net: bpf: Handle return value of BPF_CGROUP_RUN_PROG_INET{4,6}_POST_BIND() 2022-01-06 17:08:35 -08:00
proc.c Revert "net: snmp: add statistics for tcp small queue check" 2021-12-01 19:06:09 -08:00
protocol.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
raw_diag.c net: Use nlmsg_unicast() instead of netlink_unicast() 2021-07-13 09:28:29 -07:00
raw.c ipv4/raw: support binding to nonlocal addresses 2021-11-17 20:21:52 -08:00
route.c Namespaceify mtu_expires sysctl 2022-01-04 12:40:22 +00:00
syncookies.c net: align static siphash keys 2021-11-16 19:07:54 -08:00
sysctl_net_ipv4.c tcp: remove sk_{tr}x_skb_cache 2021-09-23 12:50:26 +01:00
tcp_bbr.c bpf: Enable TCP congestion control kfunc from modules 2021-10-05 17:07:41 -07:00
tcp_bic.c
tcp_bpf.c bpf, sockmap: Fix return codes from tcp_bpf_recvmsg_parser() 2022-01-05 20:43:08 +01:00
tcp_cdg.c
tcp_cong.c net: Only allow init netns to set default tcp cong to a restricted algo 2021-05-04 11:58:28 -07:00
tcp_cubic.c tcp_cubic: fix spurious Hystart ACK train detections for not-cwnd-limited flows 2021-11-24 17:26:05 -08:00
tcp_dctcp.c bpf: Enable TCP congestion control kfunc from modules 2021-10-05 17:07:41 -07:00
tcp_dctcp.h
tcp_diag.c
tcp_fastopen.c net/ipv4/tcp_fastopen.c: remove superfluous header files from tcp_fastopen.c 2021-09-20 13:09:06 +01:00
tcp_highspeed.c Replace HTTP links with HTTPS ones: IPv* 2020-07-06 13:23:03 -07:00
tcp_htcp.c Replace HTTP links with HTTPS ones: IPv* 2020-07-06 13:23:03 -07:00
tcp_hybla.c
tcp_illinois.c
tcp_input.c tcp: tcp_send_challenge_ack delete useless param skb 2022-01-09 16:52:21 -08:00
tcp_ipv4.c net: skb: use kfree_skb_reason() in tcp_v4_rcv() 2022-01-09 16:30:34 -08:00
tcp_lp.c ipv4: tcp_lp.c: Couple of typo fixes 2021-03-28 17:31:13 -07:00
tcp_metrics.c fixes-v5.11 2020-12-14 16:40:27 -08:00
tcp_minisocks.c tcp: fix another uninit-value (sk_rx_queue_mapping) 2021-12-03 14:15:49 +00:00
tcp_nv.c net/ipv4/tcp_nv.c: remove superfluous header files from tcp_nv.c 2021-09-27 12:47:39 +01:00
tcp_offload.c net: move gro definitions to include/net/gro.h 2021-11-16 13:16:54 +00:00
tcp_output.c Revert "net: snmp: add statistics for tcp small queue check" 2021-12-01 19:06:09 -08:00
tcp_rate.c tcp: tracking packets with CE marks in BW rate sample 2021-09-24 14:16:40 +01:00
tcp_recovery.c tcp: more accurately check DSACKs to grow RACK reordering window 2021-07-27 20:07:21 +01:00
tcp_scalable.c net: ipv4: delete repeated words 2020-08-24 17:31:20 -07:00
tcp_timer.c net: sock: introduce sk_error_report 2021-06-29 11:28:21 -07:00
tcp_ulp.c
tcp_vegas.c tcp: use semicolons rather than commas to separate statements 2020-10-13 17:11:52 -07:00
tcp_vegas.h
tcp_veno.c Replace HTTP links with HTTPS ones: IPv* 2020-07-06 13:23:03 -07:00
tcp_westwood.c
tcp_yeah.c tcp_yeah: check struct yeah size at compile time 2021-06-29 11:54:36 -07:00
tcp.c tcp: add a missing sk_defer_free_flush() in tcp_splice_read() 2022-01-20 20:17:50 -08:00
tunnel4.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
udp_bpf.c net: Implement ->sock_is_readable() for UDP and AF_UNIX 2021-10-26 12:29:33 -07:00
udp_diag.c net: Use nlmsg_unicast() instead of netlink_unicast() 2021-07-13 09:28:29 -07:00
udp_impl.h net: pass a sockptr_t into ->setsockopt 2020-07-24 15:41:54 -07:00
udp_offload.c gro: remove rcu_read_lock/rcu_read_unlock from gro_complete handlers 2021-11-24 17:21:42 -08:00
udp_tunnel_core.c net/ipv4/udp_tunnel_core.c: remove superfluous header files from udp_tunnel_core.c 2021-09-21 10:17:20 +01:00
udp_tunnel_nic.c udp_tunnel: Fix udp_tunnel_nic work-queue type 2021-09-13 12:38:45 +01:00
udp_tunnel_stub.c udp_tunnel: add central NIC RX port offload infrastructure 2020-07-10 13:54:00 -07:00
udp.c net: skb: use kfree_skb_reason() in __udp4_lib_rcv() 2022-01-09 16:30:35 -08:00
udplite.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
xfrm4_input.c
xfrm4_output.c xfrm: fix unused variable warning if CONFIG_NETFILTER=n 2020-05-11 15:12:27 +02:00
xfrm4_policy.c xfrm: use net device refcount tracker helpers 2021-12-09 11:51:45 -08:00
xfrm4_protocol.c net: Remove the member netns_ok 2021-05-17 15:29:35 -07:00
xfrm4_state.c
xfrm4_tunnel.c net/ipv4/xfrm4_tunnel.c: remove superfluous header files from xfrm4_tunnel.c 2021-09-23 10:10:00 +02:00