linux/include/net/netns, branch v4.2

netfilter: fix netns dependencies with conntrack templates

2015-07-20T12:58:19Z

Quoting Daniel Borkmann: "When adding connection tracking template rules to a netns, f.e. to configure netfilter zones, the kernel will endlessly busy-loop as soon as we try to delete the given netns in case there's at least one template present, which is problematic i.e. if there is such bravery that the priviledged user inside the netns is assumed untrusted. Minimal example: ip netns add foo ip netns exec foo iptables -t raw -A PREROUTING -d 1.2.3.4 -j CT --zone 1 ip netns del foo What happens is that when nf_ct_iterate_cleanup() is being called from nf_conntrack_cleanup_net_list() for a provided netns, we always end up with a net->ct.count > 0 and thus jump back to i_see_dead_people. We don't get a soft-lockup as we still have a schedule() point, but the serving CPU spins on 100% from that point onwards. Since templates are normally allocated with nf_conntrack_alloc(), we also bump net->ct.count. The issue why they are not yet nf_ct_put() is because the per netns .exit() handler from x_tables (which would eventually invoke xt_CT's xt_ct_tg_destroy() that drops reference on info->ct) is called in the dependency chain at a *later* point in time than the per netns .exit() handler for the connection tracker. This is clearly a chicken'n'egg problem: after the connection tracker .exit() handler, we've teared down all the connection tracking infrastructure already, so rightfully, xt_ct_tg_destroy() cannot be invoked at a later point in time during the netns cleanup, as that would lead to a use-after-free. At the same time, we cannot make x_tables depend on the connection tracker module, so that the xt_ct_tg_destroy() would be invoked earlier in the cleanup chain." Daniel confirms this has to do with the order in which modules are loaded or having compiled nf_conntrack as modules while x_tables built-in. So we have no guarantees regarding the order in which netns callbacks are executed. Fix this by allocating the templates through kmalloc() from the respective SYNPROXY and CT targets, so they don't depend on the conntrack kmem cache. Then, release then via nf_ct_tmpl_free() from destroy_conntrack(). This branch is marked as unlikely since conntrack templates are rarely allocated and only from the configuration plane path. Note that templates are not kept in any list to avoid further dependencies with nf_conntrack anymore, thus, the tmpl larval list is removed. Reported-by: Daniel Borkmann Signed-off-by: Pablo Neira Ayuso Tested-by: Daniel Borkmann

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2015-06-24T09:58:51Z

Conflicts: drivers/net/ethernet/mellanox/mlx4/main.c net/packet/af_packet.c Both conflicts were cases of simple overlapping changes. Signed-off-by: David S. Miller

netfilter: don't pull include/linux/netfilter.h from netns headers

2015-06-18T19:14:31Z

This pulls the full hook netfilter definitions from all those that include net_namespace.h. Instead let's just include the bare minimum required in the new linux/netfilter_defs.h file, and use it from the netfilter netns header files. I also needed to include in.h and in6.h from linux/netfilter.h otherwise we hit this compilation error: In file included from include/linux/netfilter_defs.h:4:0, from include/net/netns/netfilter.h:4, from include/net/net_namespace.h:22, from include/linux/netdevice.h:43, from net/netfilter/nfnetlink_queue_core.c:23: include/uapi/linux/netfilter.h:76:17: error: field ‘in’ has incomplete type struct in_addr in; And also explicit include linux/netfilter.h in several spots. Signed-off-by: Pablo Neira Ayuso Signed-off-by: Eric W. Biederman

netfilter: use forward declaration instead of including linux/proc_fs.h

2015-06-18T19:14:30Z

We don't need to pull the full definitions in that file, a simple forward declaration is enough. Moreover, include linux/procfs.h from nf_synproxy_core, otherwise this hits a compilation error due to missing declarations, ie. net/netfilter/nf_synproxy_core.c: In function ‘synproxy_proc_init’: net/netfilter/nf_synproxy_core.c:326:2: error: implicit declaration of function ‘proc_create’ [-Werror=implicit-function-declaration] if (!proc_create("synproxy", S_IRUGO, net->proc_net_stat, ^ Signed-off-by: Pablo Neira Ayuso Signed-off-by: Eric W. Biederman

sctp: fix ASCONF list handling

2015-06-14T19:55:49Z

->auto_asconf_splist is per namespace and mangled by functions like sctp_setsockopt_auto_asconf() which doesn't guarantee any serialization. Also, the call to inet_sk_copy_descendant() was backuping ->auto_asconf_list through the copy but was not honoring ->do_auto_asconf, which could lead to list corruption if it was different between both sockets. This commit thus fixes the list handling by using ->addr_wq_lock spinlock to protect the list. A special handling is done upon socket creation and destruction for that. Error handlig on sctp_init_sock() will never return an error after having initialized asconf, so sctp_destroy_sock() can be called without addrq_wq_lock. The lock now will be take on sctp_close_sock(), before locking the socket, so we don't do it in inverse order compared to sctp_addr_wq_timeout_handler(). Instead of taking the lock on sctp_sock_migrate() for copying and restoring the list values, it's preferred to avoid rewritting it by implementing sctp_copy_descendant(). Issue was found with a test application that kept flipping sysctl default_auto_asconf on and off, but one could trigger it by issuing simultaneous setsockopt() calls on multiple sockets or by creating/destroying sockets fast enough. This is only triggerable locally. Fixes: 9f7d653b67ae ("sctp: Add Auto-ASCONF support (core).") Reported-by: Ji Jianwen Suggested-by: Neil Horman Suggested-by: Hannes Frederic Sowa Acked-by: Hannes Frederic Sowa Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next

2015-05-31T07:02:30Z

Pablo Neira Ayuso says: ==================== Netfilter updates for net-next The following patchset contains Netfilter updates for net-next, they are: 1) default CONFIG_NETFILTER_INGRESS to y for easier compile-testing of all options. 2) Allow to bind a table to net_device. This introduces the internal NFT_AF_NEEDS_DEV flag to perform a mandatory check for this binding. This is required by the next patch. 3) Add the 'netdev' table family, this new table allows you to create ingress filter basechains. This provides access to the existing nf_tables features from ingress. 4) Kill unused argument from compat_find_calc_{match,target} in ip_tables and ip6_tables, from Florian Westphal. ==================== Signed-off-by: David S. Miller

tcp/dccp: warn user for preferred ip_local_port_range

2015-05-27T18:35:36Z

After commit 07f4c90062f8f ("tcp/dccp: try to not exhaust ip_local_port_range in connect()") it is advised to have an even number of ports described in /proc/sys/net/ipv4/ip_local_port_range This means start/end values should have a different parity. Let's warn sysadmins of this, so that they can update their settings if they want to. Suggested-by: David S. Miller Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

netfilter: nf_tables: add netdev table to filter from ingress

2015-05-26T16:41:23Z

This allows us to create netdev tables that contain ingress chains. Use skb_header_pointer() as we may see shared sk_buffs at this stage. This change provides access to the existing nf_tables features from the ingress hook. Signed-off-by: Pablo Neira Ayuso

tcp: add rfc3168, section 6.1.1.1. fallback

2015-05-19T20:53:37Z

This work as a follow-up of commit f7b3bec6f516 ("net: allow setting ecn via routing table") and adds RFC3168 section 6.1.1.1. fallback for outgoing ECN connections. In other words, this work adds a retry with a non-ECN setup SYN packet, as suggested from the RFC on the first timeout: [...] A host that receives no reply to an ECN-setup SYN within the normal SYN retransmission timeout interval MAY resend the SYN and any subsequent SYN retransmissions with CWR and ECE cleared. [...] Schematic client-side view when assuming the server is in tcp_ecn=2 mode, that is, Linux default since 2009 via commit 255cac91c3c9 ("tcp: extend ECN sysctl to allow server-side only ECN"): 1) Normal ECN-capable path: SYN ECE CWR -----> <----- SYN ACK ECE ACK -----> 2) Path with broken middlebox, when client has fallback: SYN ECE CWR ----X crappy middlebox drops packet (timeout, rtx) SYN -----> <----- SYN ACK ACK -----> In case we would not have the fallback implemented, the middlebox drop point would basically end up as: SYN ECE CWR ----X crappy middlebox drops packet (timeout, rtx) SYN ECE CWR ----X crappy middlebox drops packet (timeout, rtx) SYN ECE CWR ----X crappy middlebox drops packet (timeout, rtx) In any case, it's rather a smaller percentage of sites where there would occur such additional setup latency: it was found in end of 2014 that ~56% of IPv4 and 65% of IPv6 servers of Alexa 1 million list would negotiate ECN (aka tcp_ecn=2 default), 0.42% of these webservers will fail to connect when trying to negotiate with ECN (tcp_ecn=1) due to timeouts, which the fallback would mitigate with a slight latency trade-off. Recent related paper on this topic: Brian Trammell, Mirja Kühlewind, Damiano Boppart, Iain Learmonth, Gorry Fairhurst, and Richard Scheffenegger: "Enabling Internet-Wide Deployment of Explicit Congestion Notification." Proc. PAM 2015, New York. http://ecn.ethz.ch/ecn-pam15.pdf Thus, when net.ipv4.tcp_ecn=1 is being set, the patch will perform RFC3168, section 6.1.1.1. fallback on timeout. For users explicitly not wanting this which can be in DC use case, we add a net.ipv4.tcp_ecn_fallback knob that allows for disabling the fallback. tp->ecn_flags are not being cleared in tcp_ecn_clear_syn() on output, but rather we let tcp_ecn_rcv_synack() take that over on input path in case a SYN ACK ECE was delayed. Thus a spurious SYN retransmission will not prevent ECN being negotiated eventually in that case. Reference: https://www.ietf.org/proceedings/92/slides/slides-92-iccrg-1.pdf Reference: https://www.ietf.org/proceedings/89/slides/slides-89-tsvarea-1.pdf Signed-off-by: Daniel Borkmann Signed-off-by: Florian Westphal Signed-off-by: Mirja Kühlewind Signed-off-by: Brian Trammell Cc: Eric Dumazet Cc: Dave That Acked-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: Flow label state ranges

2015-05-04T01:58:01Z

This patch divides the IPv6 flow label space into two ranges: 0-7ffff is reserved for flow label manager, 80000-fffff will be used for creating auto flow labels (per RFC6438). This only affects how labels are set on transmit, it does not affect receive. This range split can be disbaled by systcl. Background: IPv6 flow labels have been an unmitigated disappointment thus far in the lifetime of IPv6. Support in HW devices to use them for ECMP is lacking, and OSes don't turn them on by default. If we had these we could get much better hashing in IPv6 networks without resorting to DPI, possibly eliminating some of the motivations to to define new encaps in UDP just for getting ECMP. Unfortunately, the initial specfications of IPv6 did not clarify how they are to be used. There has always been a vague concept that these can be used for ECMP, flow hashing, etc. and we do now have a good standard how to this in RFC6438. The problem is that flow labels can be either stateful or stateless (as in RFC6438), and we are presented with the possibility that a stateless label may collide with a stateful one. Attempts to split the flow label space were rejected in IETF. When we added support in Linux for RFC6438, we could not turn on flow labels by default due to this conflict. This patch splits the flow label space and should give us a path to enabling auto flow labels by default for all IPv6 packets. This is an API change so we need to consider compatibility with existing deployment. The stateful range is chosen to be the lower values in hopes that most uses would have chosen small numbers. Once we resolve the stateless/stateful issue, we can proceed to look at enabling RFC6438 flow labels by default (starting with scaled testing). Signed-off-by: Tom Herbert Signed-off-by: David S. Miller