aboutsummaryrefslogtreecommitdiffstats
path: root/net/netfilter/nf_tables_api.c (follow)
AgeCommit message (Collapse)AuthorFilesLines
2014-10-02netfilter: nf_tables: wait for call_rcu completion on module removalPablo Neira Ayuso1-0/+1
Make sure the objects have been released before the nf_tables modules is removed. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-09-29netfilter: nf_tables: store and dump set policyArturo Borrero1-0/+6
We want to know in which cases the user explicitly sets the policy options. In that case, we also want to dump back the info. Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-09-19netfilter: nf_tables: export rule-set generation IDPablo Neira Ayuso1-26/+114
This patch exposes the ruleset generation ID in three ways: 1) The new command NFT_MSG_GETGEN that exposes the 32-bits ruleset generation ID. This ID is incremented in every commit and it should be large enough to avoid wraparound problems. 2) The less significant 16-bits of the generation ID are exposed through the nfgenmsg->res_id header field. This allows us to quickly catch if the ruleset has change between two consecutive list dumps from different object lists (in this specific case I think the risk of wraparound is unlikely). 3) Userspace subscribers may receive notifications of new rule-set generation after every commit. This also provides an alternative way to monitor the generation ID. If the events are lost, the userspace process hits a overrun error, so it knows that it is working with a stale ruleset anyway. Patrick spotted that rule-set transformations in userspace may take quite some time. In that case, it annotates the 32-bits generation ID before fetching the rule-set, then: 1) it compares it to what we obtain after the transformation to make sure it is not working with a stale rule-set and no wraparound has ocurred. 2) it subscribes to ruleset notifications, so it can watch for new generation ID. This is complementary to the NLM_F_DUMP_INTR approach, which allows us to detect an interference in the middle one single list dumping. There is no way to explicitly check that an interference has occurred between two list dumps from the kernel, since it doesn't know how many lists the userspace client is actually going to dump. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-09-09netfilter: nf_tables: extend NFT_MSG_DELTABLE to support flushing the rulesetArturo Borrero1-4/+68
This patch extend the NFT_MSG_DELTABLE call to support flushing the entire ruleset. The options now are: * No family speficied, no table specified: flush all the ruleset. * Family specified, no table specified: flush all tables in the AF. * Family specified, table specified: flush the given table. Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-09-09netfilter: nf_tables: add helpers to schedule objects deletionArturo Borrero1-169/+194
This patch refactor the code to schedule objects deletion. They are useful in follow-up patches. In order to be able to use these new helper functions in all the code, they are placed in the top of the file, with all the dependant functions and symbols. nft_rule_disactivate_next has been renamed to nft_rule_deactivate. Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-09-09netfilter: nf_tables: rename nf_table_delrule_by_chain()Arturo Borrero1-3/+3
For the sake of homogenize the function naming scheme, let's rename nf_table_delrule_by_chain() to nft_delrule_by_chain(). Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-09-09netfilter: nf_tables: add helper to unregister chain hooksArturo Borrero1-15/+16
This patch adds a helper function to unregister chain hooks in the chain deletion path. Basically, a code factorization. The new function is useful in follow-up patches. Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-09-09netfilter: nf_tables: refactor rule deletion helperArturo Borrero1-5/+21
This helper function always schedule the rule to be removed in the following transaction. In follow-up patches, it is interesting to handle separately the logic of rule activation/disactivation from the transaction mechanism. So, this patch simply splits the original nf_tables_delrule_one() in two functions, allowing further control. While at it, for the sake of homigeneize the function naming scheme, let's rename nf_tables_delrule_one() to nft_delrule(). Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-08-08netfilter: nf_tables: fix error return codeJulia Lawall1-1/+3
Convert a zero return value on error to a negative one, as returned elsewhere in the function. A simplified version of the semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/) // <smpl> @@ identifier ret; expression e1,e2; @@ ( if (\(ret < 0\|ret != 0\)) { ... return ret; } | ret = 0 ) ... when != ret = e1 when != &ret *if(...) { ... when != ret = e2 when forall return ret; } // </smpl> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-08-08netfilter: nf_tables: don't update chain with unset countersPablo Neira Ayuso1-0/+3
Fix possible replacement of the per-cpu chain counters by null pointer when updating an existing chain in the commit path. Reported-by: Matteo Croce <technoboy85@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-08-08netfilter: nf_tables: uninitialize element key/data from the commit pathPablo Neira Ayuso1-12/+11
This should happen once the element has been effectively released in the commit path, not before. This fixes a possible chain refcount leak if the transaction is aborted. Reported-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-08-05Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller1-0/+1
Conflicts: drivers/net/Makefile net/ipv6/sysctl_net_ipv6.c Two ipv6_table_template[] additions overlap, so the index of the ipv6_table[x] assignments needed to be adjusted. In the drivers/net/Makefile case, we've gotten rid of the garbage whereby we had to list every single USB networking driver in the top-level Makefile, there is just one "USB_NETWORKING" that guards everything. Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-01netfilter: nf_tables: Avoid duplicate call to nft_data_uninit() for same keyThomas Graf1-0/+1
nft_del_setelem() currently calls nft_data_uninit() twice on the same key. Once to release the key which is guaranteed to be NFT_DATA_VALUE and a second time in the error path to which it falls through. The second call has been harmless so far though because the type passed is always NFT_DATA_VALUE which is currently a no-op. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-07-31netfilter: nf_tables: check for unset NFTA_SET_ELEM_LIST_ELEMENTS attributePablo Neira Ayuso1-0/+6
Otherwise, the kernel oopses in nla_for_each_nested when iterating over the unset attribute NFTA_SET_ELEM_LIST_ELEMENTS in the nf_tables_{new,del}setelem() path. netlink: 65524 bytes leftover after parsing attributes in process `nft'. [...] Oops: 0000 [#1] SMP [...] CPU: 2 PID: 6287 Comm: nft Not tainted 3.16.0-rc2+ #169 RIP: 0010:[<ffffffffa0526e61>] [<ffffffffa0526e61>] nf_tables_newsetelem+0x82/0xec [nf_tables] [...] Call Trace: [<ffffffffa05178c4>] nfnetlink_rcv+0x2e7/0x3d7 [nfnetlink] [<ffffffffa0517939>] ? nfnetlink_rcv+0x35c/0x3d7 [nfnetlink] [<ffffffff8137d300>] netlink_unicast+0xf8/0x17a [<ffffffff8137d6a5>] netlink_sendmsg+0x323/0x351 [...] Fix this by returning -EINVAL if this attribute is not set, which doesn't make sense at all since those commands are there to add and to delete elements from the set. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-07-22netfilter: nf_tables: simplify set dump through netlinkPablo Neira Ayuso1-104/+27
This patch uses the cb->data pointer that allows us to store the context when dumping the set list. Thus, we don't need to parse the original netlink message containing the dump request for each recvmsg() call when dumping the set list. The different function flavours depending on the dump criteria has been also merged into one single generic function. This saves us ~100 lines of code. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-07-14netfilter: nf_tables: 64bit stats need some extra synchronizationEric Dumazet1-4/+11
Use generic u64_stats_sync infrastructure to get proper 64bit stats, even on 32bit arches, at no extra cost for 64bit arches. Without this fix, 32bit arches can have some wrong counters at the time the carry is propagated into upper word. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-07-14netfilter: nf_tables: set NLM_F_DUMP_INTR if netlink dumping is stalePablo Neira Ayuso1-7/+23
An updater may interfer with the dumping of any of the object lists. Fix this by using a per-net generation counter and use the nl_dump_check_consistent() interface so the NLM_F_DUMP_INTR flag is set to notify userspace that it has to restart the dump since an updater has interfered. This patch also replaces the existing consistency checking code in the rule dumping path since it is broken. Basically, the value that the dump callback returns is not propagated to userspace via netlink_dump_start(). Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-07-14netfilter: nf_tables: safe RCU iteration on list when dumpingPablo Neira Ayuso1-41/+53
The dump operation through netlink is not protected by the nfnl_lock. Thus, a reader process can be dumping any of the existing object lists while another process can be updating the list content. This patch resolves this situation by protecting all the object lists with RCU in the netlink dump path which is the reader side. The updater path is already protected via nfnl_lock, so use list manipulation RCU-safe operations. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-30netfilter: nf_tables: skip transaction if no update flags in tablesPablo Neira Ayuso1-0/+3
Skip transaction handling for table updates with no changes in the flags. This fixes a crash when passing the table flag with all bits unset. Reported-by: Ana Rey <anarey@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-16netfilter: nf_tables: indicate family when dumping set elementsPablo Neira Ayuso1-1/+1
Set the nfnetlink header that indicates the family of this element. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-16netfilter: nf_tables: fix wrong type in transaction when replacing rulesPablo Neira Ayuso1-1/+1
In b380e5c ("netfilter: nf_tables: add message type to transactions"), I used the wrong message type in the rule replacement case. The rule that is replaced needs to be handled as a deleted rule. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-16netfilter: nf_tables: decrement chain use counter when replacing rulesPablo Neira Ayuso1-0/+2
Thus, the chain use counter remains with the same value after the rule replacement. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-16netfilter: nf_tables: use u32 for chain use counterPablo Neira Ayuso1-0/+3
Since 4fefee5 ("netfilter: nf_tables: allow to delete several objects from a batch"), every new rule bumps the chain use counter. However, this is limited to 16 bits, which means that it will overrun after 2^16 rules. Use a u32 chain counter and check for overflows (just like we do for table objects). Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-16netfilter: nf_tables: use RCU-safe list insertion when replacing rulesPablo Neira Ayuso1-1/+1
The patch 5e94846 ("netfilter: nf_tables: add insert operation") did not include RCU-safe list insertion when replacing rules. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-02netfilter: nf_tables: atomic allocation in set notifications from rcu callbackPablo Neira Ayuso1-6/+6
Use GFP_ATOMIC allocations when sending removal notifications of anonymous sets from rcu callback context. Sleeping in that context is illegal. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-02netfilter: nf_tables: allow to delete several objects from a batchPablo Neira Ayuso1-9/+31
Three changes to allow the deletion of several objects with dependencies in one transaction, they are: 1) Introduce speculative counter increment/decrement that is undone in the abort path if required, thus we avoid hitting -EBUSY when deleting the chain. The counter updates are reverted in the abort path. 2) Increment/decrement table/chain use counter for each set/rule. We need this to fully rely on the use counters instead of the list content, eg. !list_empty(&chain->rules) which evaluate true in the middle of the transaction. 3) Decrement table use counter when an anonymous set is bound to the rule in the commit path. This avoids hitting -EBUSY when deleting the table that contains anonymous sets. The anonymous sets are released in the nf_tables_rule_destroy path. This should not be a problem since the rule already bumped the use counter of the chain, so the bound anonymous set reflects dependencies through the rule object, which already increases the chain use counter. So the general assumption after this patch is that the use counters are bumped by direct object dependencies. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-02netfilter: nf_tables: release objects in reverse order in the abort pathPablo Neira Ayuso1-1/+2
The patch c7c32e7 ("netfilter: nf_tables: defer all object release via rcu") indicates that we always release deleted objects in the reverse order, but that is only needed in the abort path. These are the two possible scenarios when releasing objects: 1) Deletion scenario in the commit path: no need to release objects in the reverse order since userspace already ensures that dependencies are fulfilled), ie. userspace tells us to delete rule -> ... -> rule -> chain -> table. In this case, we have to release the objects in the *same order* as userspace provided. 2) Deletion scenario in the abort path: we have to iterate in the reverse order to undo what it cannot be added, ie. userspace sent us a batch that includes: table -> chain -> rule -> ... -> rule, and that needs to be partially undone. In this case, we have to release objects in the reverse order to ensure that the set and chain objects point to valid rule and table objects. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-06-02netfilter: nf_tables: fix wrong transaction ordering in set elementsPablo Neira Ayuso1-2/+2
The transaction needs to be placed at the end of the commit list, otherwise event notifications are reordered and we may crash when releasing object via call_rcu. This problem was introduced in 60319eb ("netfilter: nf_tables: use new transaction infrastructure to handle elements"). Reported-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-22Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nftablesDavid S. Miller1-342/+894
Pablo Neira Ayuso says: ==================== Netfilter/nftables updates for net-next The following patchset contains Netfilter/nftables updates for net-next, most relevantly they are: 1) Add set element update notification via netlink, from Arturo Borrero. 2) Put all object updates in one single message batch that is sent to kernel-space. Before this patch only rules where included in the batch. This series also introduces the generic transaction infrastructure so updates to all objects (tables, chains, rules and sets) are applied in an all-or-nothing fashion, these series from me. 3) Defer release of objects via call_rcu to reduce the time required to commit changes. The assumption is that all objects are destroyed in reverse order to ensure that dependencies betweem them are fulfilled (ie. rules and sets are destroyed first, then chains, and finally tables). 4) Allow to match by bridge port name, from Tomasz Bursztyka. This series include two patches to prepare this new feature. 5) Implement the proper set selection based on the characteristics of the data. The new infrastructure also allows you to specify your preferences in terms of memory and computational complexity so the underlying set type is also selected according to your needs, from Patrick McHardy. 6) Several cleanup patches for nft expressions, including one minor possible compilation breakage due to missing mark support, also from Patrick. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2014-05-19netfilter: nf_tables: defer all object release via rcuPablo Neira Ayuso1-39/+54
Now that all objects are released in the reverse order via the transaction infrastructure, we can enqueue the release via call_rcu to save one synchronize_rcu. For small rule-sets loaded via nft -f, it now takes around 50ms less here. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: remove skb and nlh from context structurePablo Neira Ayuso1-55/+46
Instead of caching the original skbuff that contains the netlink messages, this stores the netlink message sequence number, the netlink portID and the report flag. This helps to prepare the introduction of the object release via call_rcu. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: simplify nf_tables_*_notifyPablo Neira Ayuso1-58/+32
Now that all these function are called from the commit path, we can pass the context structure to reduce the amount of parameters in all of the nf_tables_*_notify functions. This patch also removes unneeded branches to check for skb, nlh and net that should be always set in the context structure. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: use new transaction infrastructure to handle elementsPablo Neira Ayuso1-14/+68
Leave the set content in consistent state if we fail to load the batch. Use the new generic transaction infrastructure to achieve this. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: use new transaction infrastructure to handle tablePablo Neira Ayuso1-19/+126
This patch speeds up rule-set updates and it also provides a way to revert updates and leave things in consistent state in case that the batch needs to be aborted. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: pass context to nf_tables_updtable()Pablo Neira Ayuso1-25/+26
So nf_tables_uptable() only takes one single parameter. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: disabling table hooks always succeedsPablo Neira Ayuso1-6/+3
nf_tables_table_disable() always succeeds, make this function void. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: use new transaction infrastructure to handle chainPablo Neira Ayuso1-45/+158
This patch speeds up rule-set updates and it also introduces a way to revert chain updates if the batch is aborted. The idea is to store the changes in the transaction to apply that in the commit step. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: refactor chain statistic routinesPablo Neira Ayuso1-21/+24
Add new routines to encapsulate chain statistics allocation and replacement. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: use new transaction infrastructure to handle setsPablo Neira Ayuso1-16/+107
This patch reworks the nf_tables API so set updates are included in the same batch that contains rule updates. This speeds up rule-set updates since we skip a dialog of four messages between kernel and user-space (two on each direction), from: 1) create the set and send netlink message to the kernel 2) process the response from the kernel that contains the allocated name. 3) add the set elements and send netlink message to the kernel. 4) process the response from the kernel (to check for errors). To: 1) add the set to the batch. 2) add the set elements to the batch. 3) add the rule that points to the set. 4) send batch to the kernel. This also introduces an internal set ID (NFTA_SET_ID) that is unique in the batch so set elements and rules can refer to new sets. Backward compatibility has been only retained in userspace, this means that new nft versions can talk to the kernel both in the new and the old fashion. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: add message type to transactionsPablo Neira Ayuso1-31/+43
The patch adds message type to the transaction to simplify the commit the and abort routines. Yet another step forward in the generalisation of the transaction infrastructure. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: relocate commit and abort routines in the source filePablo Neira Ayuso1-80/+80
Move the commit and abort routines to the bottom of the source code file. This change is required by the follow up patches that add the set, chain and table transaction support. This patch is just a cleanup to access several functions without having to declare their prototypes. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: generalise transaction infrastructurePablo Neira Ayuso1-54/+69
This patch generalises the existing rule transaction infrastructure so it can be used to handle set, table and chain object transactions as well. The transaction provides a data area that stores private information depending on the transaction type. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-05-19netfilter: nf_tables: deconstify table and chain in context structurePablo Neira Ayuso1-29/+29
The new transaction infrastructure updates the family, table and chain objects in the context structure, so let's deconstify them. While at it, move the context structure initialization routine to the top of the source file as it will be also used from the table and chain routines. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-04-28netfilter: nf_tables: relax string validation of NFTA_CHAIN_TYPEPablo Neira1-1/+1
Use NLA_STRING for consistency with other string attributes in nf_tables. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-04-23netfilter: nf_tables: Stack expression type depending on their familyTomasz Bursztyka1-1/+4
To ensure family tight expression gets selected in priority to family agnostic ones. Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-04-14netfilter: nf_tables: handle more than 8 * PAGE_SIZE set name allocationsPatrick McHardy1-5/+10
We currently have a limit of 8 * PAGE_SIZE anonymous sets. Lift that limit by continuing the scan if the entire page is exhausted. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-04-03netfilter: nf_tables: fix wrong format in request_module()Pablo Neira Ayuso1-2/+2
The intended format in request_module is %.*s instead of %*.s. Reported-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-04-03netfilter: nf_tables: set names cannot be larger than 15 bytesPablo Neira Ayuso1-1/+2
Currently, nf_tables trims off the set name if it exceeeds 15 bytes, so explicitly reject set names that are too large. Reported-by: Giuseppe Longo <giuseppelng@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2014-04-03netfilter: nf_tables: add set_elem notificationsArturo Borrero1-0/+82
This patch adds set_elems notifications. When a set_elem is added/deleted, all listening peers in userspace will receive the corresponding notification. Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> Acked-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>
2014-04-02netfilter: nf_tables: implement proper set selectionPatrick McHardy1-16/+105
The current set selection simply choses the first set type that provides the requested features, which always results in the rbtree being chosen by virtue of being the first set in the list. What we actually want to do is choose the implementation that can provide the requested features and is optimal from either a performance or memory perspective depending on the characteristics of the elements and the preferences specified by the user. The elements are not known when creating a set. Even if we would provide them for anonymous (literal) sets, we'd still have standalone sets where the elements are not known in advance. We therefore need an abstract description of the data charcteristics. The kernel already knows the size of the key, this patch starts by introducing a nested set description which so far contains only the maximum amount of elements. Based on this the set implementations are changed to provide an estimate of the required amount of memory and the lookup complexity class. The set ops have a new callback ->estimate() that is invoked during set selection. It receives a structure containing the attributes known to the kernel and is supposed to populate a struct nft_set_estimate with the complexity class and, in case the size is known, the complete amount of memory required, or the amount of memory required per element otherwise. Based on the policy specified by the user (performance/memory, defaulting to performance) the kernel will then select the best suited implementation. Even if the set implementation would allow to add more than the specified maximum amount of elements, they are enforced since new implementations might not be able to add more than maximum based on which they were selected. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>