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8e39cbc03d
commit5f3e2bf008upstream. 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 commitc39508d6f1("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>
142 lines
3.2 KiB
C
142 lines
3.2 KiB
C
/*
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* ipv4 in net namespaces
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*/
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#ifndef __NETNS_IPV4_H__
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#define __NETNS_IPV4_H__
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#include <linux/uidgid.h>
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#include <net/inet_frag.h>
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#include <linux/rcupdate.h>
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struct tcpm_hash_bucket;
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struct ctl_table_header;
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struct ipv4_devconf;
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struct fib_rules_ops;
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struct hlist_head;
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struct fib_table;
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struct sock;
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struct local_ports {
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seqlock_t lock;
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int range[2];
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bool warned;
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};
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struct ping_group_range {
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seqlock_t lock;
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kgid_t range[2];
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};
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struct netns_ipv4 {
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#ifdef CONFIG_SYSCTL
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struct ctl_table_header *forw_hdr;
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struct ctl_table_header *frags_hdr;
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struct ctl_table_header *ipv4_hdr;
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struct ctl_table_header *route_hdr;
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struct ctl_table_header *xfrm4_hdr;
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#endif
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struct ipv4_devconf *devconf_all;
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struct ipv4_devconf *devconf_dflt;
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#ifdef CONFIG_IP_MULTIPLE_TABLES
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struct fib_rules_ops *rules_ops;
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bool fib_has_custom_rules;
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struct fib_table __rcu *fib_main;
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struct fib_table __rcu *fib_default;
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#endif
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#ifdef CONFIG_IP_ROUTE_CLASSID
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int fib_num_tclassid_users;
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#endif
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struct hlist_head *fib_table_hash;
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bool fib_offload_disabled;
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struct sock *fibnl;
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struct sock * __percpu *icmp_sk;
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struct sock *mc_autojoin_sk;
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struct inet_peer_base *peers;
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struct sock * __percpu *tcp_sk;
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struct netns_frags frags;
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#ifdef CONFIG_NETFILTER
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struct xt_table *iptable_filter;
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struct xt_table *iptable_mangle;
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struct xt_table *iptable_raw;
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struct xt_table *arptable_filter;
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#ifdef CONFIG_SECURITY
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struct xt_table *iptable_security;
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#endif
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struct xt_table *nat_table;
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#endif
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int sysctl_icmp_echo_ignore_all;
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int sysctl_icmp_echo_ignore_broadcasts;
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int sysctl_icmp_ignore_bogus_error_responses;
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int sysctl_icmp_ratelimit;
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int sysctl_icmp_ratemask;
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int sysctl_icmp_errors_use_inbound_ifaddr;
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struct local_ports ip_local_ports;
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int sysctl_tcp_ecn;
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int sysctl_tcp_ecn_fallback;
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int sysctl_ip_default_ttl;
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int sysctl_ip_no_pmtu_disc;
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int sysctl_ip_fwd_use_pmtu;
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int sysctl_ip_nonlocal_bind;
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/* Shall we try to damage output packets if routing dev changes? */
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int sysctl_ip_dynaddr;
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int sysctl_ip_early_demux;
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int sysctl_fwmark_reflect;
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int sysctl_tcp_fwmark_accept;
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#ifdef CONFIG_NET_L3_MASTER_DEV
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int sysctl_tcp_l3mdev_accept;
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#endif
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int sysctl_tcp_mtu_probing;
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int sysctl_tcp_base_mss;
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int sysctl_tcp_min_snd_mss;
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int sysctl_tcp_probe_threshold;
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u32 sysctl_tcp_probe_interval;
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int sysctl_tcp_keepalive_time;
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int sysctl_tcp_keepalive_probes;
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int sysctl_tcp_keepalive_intvl;
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int sysctl_tcp_syn_retries;
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int sysctl_tcp_synack_retries;
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int sysctl_tcp_syncookies;
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int sysctl_tcp_reordering;
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int sysctl_tcp_retries1;
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int sysctl_tcp_retries2;
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int sysctl_tcp_orphan_retries;
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int sysctl_tcp_fin_timeout;
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unsigned int sysctl_tcp_notsent_lowat;
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int sysctl_igmp_max_memberships;
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int sysctl_igmp_max_msf;
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int sysctl_igmp_llm_reports;
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int sysctl_igmp_qrv;
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struct ping_group_range ping_group_range;
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atomic_t dev_addr_genid;
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#ifdef CONFIG_SYSCTL
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unsigned long *sysctl_local_reserved_ports;
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#endif
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#ifdef CONFIG_IP_MROUTE
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#ifndef CONFIG_IP_MROUTE_MULTIPLE_TABLES
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struct mr_table *mrt;
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#else
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struct list_head mr_tables;
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struct fib_rules_ops *mr_rules_ops;
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#endif
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#endif
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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int sysctl_fib_multipath_use_neigh;
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#endif
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atomic_t rt_genid;
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};
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#endif
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