linux/include/net/netfilter, branch v5.1

netfilter: ctnetlink: don't use conntrack/expect object addresses as id

2019-04-15T05:31:44Z

else, we leak the addresses to userspace via ctnetlink events and dumps. Compute an ID on demand based on the immutable parts of nf_conn struct. Another advantage compared to using an address is that there is no immediate re-use of the same ID in case the conntrack entry is freed and reallocated again immediately. Fixes: 3583240249ef ("[NETFILTER]: nf_conntrack_expect: kill unique ID") Fixes: 7f85f914721f ("[NETFILTER]: nf_conntrack: kill unique ID") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: don't set related state for different outer address

2019-04-13T12:52:57Z

Luca Moro says: ------ The issue lies in the filtering of ICMP and ICMPv6 errors that include an inner IP datagram. For these packets, icmp_error_message() extract the ICMP error and inner layer to search of a known state. If a state is found the packet is tagged as related (IP_CT_RELATED). The problem is that there is no correlation check between the inner and outer layer of the packet. So one can encapsulate an error with an inner layer matching a known state, while its outer layer is directed to a filtered host. In this case the whole packet will be tagged as related. This has various implications from a rule bypass (if a rule to related trafic is allow), to a known state oracle. Unfortunately, we could not find a real statement in a RFC on how this case should be filtered. The closest we found is RFC5927 (Section 4.3) but it is not very clear. A possible fix would be to check that the inner IP source is the same than the outer destination. We believed this kind of attack was not documented yet, so we started to write a blog post about it. You can find it attached to this mail (sorry for the extract quality). It contains more technical details, PoC and discussion about the identified behavior. We discovered later that https://www.gont.com.ar/papers/filtering-of-icmp-error-messages.pdf described a similar attack concept in 2004 but without the stateful filtering in mind. ----- This implements above suggested fix: In icmp(v6) error handler, take outer destination address, then pass that into the common function that does the "related" association. After obtaining the nf_conn of the matching inner-headers connection, check that the destination address of the opposite direction tuple is the same as the outer address and only set RELATED if thats the case. Reported-by: Luca Moro Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: bogus EBUSY when deleting set after flush

2019-03-11T12:19:24Z

Set deletion after flush coming in the same batch results in EBUSY. Add set use counter to track the number of references to this set from rules. We cannot rely on the list of bindings for this since such list is still populated from the preparation phase. Reported-by: Václav Zindulka Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: fix set double-free in abort path

2019-03-08T15:41:18Z

The abort path can cause a double-free of an anonymous set. Added-and-to-be-aborted rule looks like this: udp dport { 137, 138 } drop The to-be-aborted transaction list looks like this: newset newsetelem newsetelem rule This gets walked in reverse order, so first pass disables the rule, the set elements, then the set. After synchronize_rcu(), we then destroy those in same order: rule, set element, set element, newset. Problem is that the anonymous set has already been bound to the rule, so the rule (lookup expression destructor) already frees the set, when then cause use-after-free when trying to delete the elements from this set, then try to free the set again when handling the newset expression. Rule releases the bound set in first place from the abort path, this causes the use-after-free on set element removal when undoing the new element transactions. To handle this, skip new element transaction if set is bound from the abort path. This is still causes the use-after-free on set element removal. To handle this, remove transaction from the list when the set is already bound. Joint work with Florian Westphal. Fixes: f6ac85858976 ("netfilter: nf_tables: unbind set in rule from commit path") Bugzilla: https://bugzilla.netfilter.org/show_bug.cgi?id=1325 Acked-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: nat: merge nft_masq protocol specific modules

2019-03-01T13:36:59Z

The family specific masq modules are way too small to warrant an extra module, just place all of them in nft_masq. before: text data bss dec hex filename 1001 832 0 1833 729 nft_masq.ko 766 896 0 1662 67e nft_masq_ipv4.ko 764 896 0 1660 67c nft_masq_ipv6.ko after: 2010 960 0 2970 b9a nft_masq.ko Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: nat: merge nft_redir protocol specific modules

2019-03-01T13:36:58Z

before: text data bss dec hex filename 990 832 0 1822 71e nft_redir.ko 697 896 0 1593 639 nft_redir_ipv4.ko 713 896 0 1609 649 nft_redir_ipv6.ko after: text data bss dec hex filename 1910 960 0 2870 b36 nft_redir.ko size is reduced, all helpers from nft_redir.ko can be made static. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: avoid same-timeout update

2019-02-27T09:58:21Z

No need to dirty a cache line if timeout is unchanged. Also, WARN() is useless here: we crash on 'skb->len' access if skb is NULL. Last, ct->timeout is u32, not 'unsigned long' so adapt the function prototype accordingly. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nat: remove nf_nat_l3proto.h and nf_nat_core.h

2019-02-27T09:54:08Z

The l3proto name is gone, its header file is the last trace. While at it, also remove nf_nat_core.h, its very small and all users include nf_nat.h too. before: text data bss dec hex filename 22948 1612 4136 28696 7018 nf_nat.ko after removal of l3proto register/unregister functions: text data bss dec hex filename 22196 1516 4136 27848 6cc8 nf_nat.ko checkpatch complains about overly long lines, but line breaks do not make things more readable and the line length gets smaller here, not larger. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nat: remove l3proto struct

2019-02-27T09:53:57Z

All l3proto function pointers have been removed. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nat: remove csum_recalc hook

2019-02-27T09:53:47Z

We can now use direct calls. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso