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* BACKPORT: tcp: add tcp_min_snd_mss sysctlEric Dumazet2019-07-181-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 5f3e2bf008c2221478101ee72f5cb4654b9fc363 upstream. Some TCP peers announce a very small MSS option in their SYN and/or SYN/ACK messages. This forces the stack to send packets with a very high network/cpu overhead. Linux has enforced a minimal value of 48. Since this value includes the size of TCP options, and that the options can consume up to 40 bytes, this means that each segment can include only 8 bytes of payload. In some cases, it can be useful to increase the minimal value to a saner value. We still let the default to 48 (TCP_MIN_SND_MSS), for compatibility reasons. Note that TCP_MAXSEG socket option enforces a minimal value of (TCP_MIN_MSS). David Miller increased this minimal value in commit c39508d6f118 ("tcp: Make TCP_MAXSEG minimum more correct.") from 64 to 88. We might in the future merge TCP_MIN_SND_MSS and TCP_MIN_MSS. CVE-2019-11479 -- tcp mss hardcoded to 48 Signed-off-by: Eric Dumazet <edumazet@google.com> Suggested-by: Jonathan Looney <jtl@netflix.com> Acked-by: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Tyler Hicks <tyhicks@canonical.com> Cc: Bruce Curtis <brucec@netflix.com> Cc: Jonathan Lemon <jonathan.lemon@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [BACKPORT to 3.10: use previous sysctrl method] Signed-off-by: syphyr@gmail.com Change-Id: Ib5e91a60fe4f4c00afc27ed92b1bd8dfe39fb7c9
* tcp: remove unused min_cwnd member of tcp_congestion_opsStanislav Fomichev2017-05-241-1/+1
| | | | | | | | | | | | | | Commit 684bad110757 "tcp: use PRR to reduce cwin in CWR state" removed all calls to min_cwnd, so we can safely remove it. Also, remove tcp_reno_min_cwnd because it was only used for min_cwnd. Signed-off-by: Stanislav Fomichev <stfomichev@yandex-team.ru> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Joe Maples <joe@frap129.org> Conflicts: include/net/tcp.h
* net: ipv6: Add sysctl for minimum prefix len acceptable in RIOs.Joel Scherpelz2017-04-131-2/+11
| | | | | | | | | | | | | | | | | | | This commit adds a new sysctl accept_ra_rt_info_min_plen that defines the minimum acceptable prefix length of Route Information Options. The new sysctl is intended to be used together with accept_ra_rt_info_max_plen to configure a range of acceptable prefix lengths. It is useful to prevent misconfigurations from unintentionally blackholing too much of the IPv6 address space (e.g., home routers announcing RIOs for fc00::/7, which is incorrect). [backport of net-next bbea124bc99df968011e76eba105fe964a4eceab] Bug: 33333670 Test: net_test passes Signed-off-by: Joel Scherpelz <jscherpelz@google.com> Acked-by: Lorenzo Colitti <lorenzo@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* ipv6: sysctl to restrict candidate source addressesErik Kline2017-04-131-0/+7
| | | | | | | | | | | | | | | | | | | | Per RFC 6724, section 4, "Candidate Source Addresses": It is RECOMMENDED that the candidate source addresses be the set of unicast addresses assigned to the interface that will be used to send to the destination (the "outgoing" interface). Add a sysctl to enable this behaviour. Signed-off-by: Erik Kline <ek@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> [Simplified back-port of net-next 3985e8a3611a93bb36789f65db862e5700aab65e] Bug: 19470192 Bug: 21832279 Bug: 22464419 Change-Id: Ib74ef945dcabe64215064f15ee1660b6524d65ce
* net: Fail explicit bind to local reserved portsSubash Abhinov Kasiviswanathan2017-04-131-0/+5
| | | | | | | | | | | | | | | | | Reserved ports may have some special use cases which are not suitable for use by general userspace applications. Currently, ports specified in ip_local_reserved_ports will not be returned only in case of automatic port assignment. Add a boolean sysctl flag 'reserved_port_bind'. Default value is 1 which preserves the existing behavior. Setting the value to 0 will prevent userspace applications from binding to these ports even when they are explicitly requested. BUG=20663075 Change-Id: Ib1071ca5bd437cd3c4f71b56147e4858f3b9ebec Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Signed-off-by: Mekala Natarajan <mekalan@codeaurora.org>
* tcp: enable sockets to use MSG_FASTOPEN by defaultYuchung Cheng2016-09-011-2/+2
| | | | | | | | | | | | | Applications have started to use Fast Open (e.g., Chrome browser has such an optional flag) and the feature has gone through several generations of kernels since 3.7 with many real network tests. It's time to enable this flag by default for applications to test more conveniently and extensively. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* first commitMeizu OpenSource2016-08-15124-0/+31379