kernel/linux.git/include/net/netfilter, branch v6.4.11

netfilter: nf_tables: GC transaction API to avoid race with control plane

2023-08-16T16:32:22+00:00

commit 5f68718b34a531a556f2f50300ead2862278da26 upstream. The set types rhashtable and rbtree use a GC worker to reclaim memory. From system work queue, in periodic intervals, a scan of the table is done. The major caveat here is that the nft transaction mutex is not held. This causes a race between control plane and GC when they attempt to delete the same element. We cannot grab the netlink mutex from the work queue, because the control plane has to wait for the GC work queue in case the set is to be removed, so we get following deadlock: cpu 1 cpu2 GC work transaction comes in , lock nft mutex `acquire nft mutex // BLOCKS transaction asks to remove the set set destruction calls cancel_work_sync() cancel_work_sync will now block forever, because it is waiting for the mutex the caller already owns. This patch adds a new API that deals with garbage collection in two steps: 1) Lockless GC of expired elements sets on the NFT_SET_ELEM_DEAD_BIT so they are not visible via lookup. Annotate current GC sequence in the GC transaction. Enqueue GC transaction work as soon as it is full. If ruleset is updated, then GC transaction is aborted and retried later. 2) GC work grabs the mutex. If GC sequence has changed then this GC transaction lost race with control plane, abort it as it contains stale references to objects and let GC try again later. If the ruleset is intact, then this GC transaction deactivates and removes the elements and it uses call_rcu() to destroy elements. Note that no elements are removed from GC lockless path, the _DEAD bit is set and pointers are collected. GC catchall does not remove the elements anymore too. There is a new set->dead flag that is set on to abort the GC transaction to deal with set->ops->destroy() path which removes the remaining elements in the set from commit_release, where no mutex is held. To deal with GC when mutex is held, which allows safe deactivate and removal, add sync GC API which releases the set element object via call_rcu(). This is used by rbtree and pipapo backends which also perform garbage collection from control plane path. Since element removal from sets can happen from control plane and element garbage collection/timeout, it is necessary to keep the set structure alive until all elements have been deactivated and destroyed. We cannot do a cancel_work_sync or flush_work in nft_set_destroy because its called with the transaction mutex held, but the aforementioned async work queue might be blocked on the very mutex that nft_set_destroy() callchain is sitting on. This gives us the choice of ABBA deadlock or UaF. To avoid both, add set->refs refcount_t member. The GC API can then increment the set refcount and release it once the elements have been free'd. Set backends are adapted to use the GC transaction API in a follow up patch entitled: ("netfilter: nf_tables: use gc transaction API in set backends") This is joint work with Florian Westphal. Fixes: cfed7e1b1f8e ("netfilter: nf_tables: add set garbage collection helpers") Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman

netfilter: conntrack: don't fold port numbers into addresses before hashing

2023-07-23T11:53:36+00:00

[ Upstream commit eaf9e7192ec9af2fbf1b6eb2299dd0feca6c5f7e ] Originally this used jhash2() over tuple and folded the zone id, the pernet hash value, destination port and l4 protocol number into the 32bit seed value. When the switch to siphash was done, I used an on-stack temporary buffer to build a suitable key to be hashed via siphash(). But this showed up as performance regression, so I got rid of the temporary copy and collected to-be-hashed data in 4 u64 variables. This makes it easy to build tuples that produce the same hash, which isn't desirable even though chain lengths are limited. Switch back to plain siphash, but just like with jhash2(), take advantage of the fact that most of to-be-hashed data is already in a suitable order. Use an empty struct as annotation in 'struct nf_conntrack_tuple' to mark last member that can be used as hash input. The only remaining data that isn't present in the tuple structure are the zone identifier and the pernet hash: fold those into the key. Fixes: d2c806abcf0b ("netfilter: conntrack: use siphash_4u64") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: nf_tables: report use refcount overflow

2023-07-23T11:53:36+00:00

[ Upstream commit 1689f25924ada8fe14a4a82c38925d04994c7142 ] Overflow use refcount checks are not complete. Add helper function to deal with object reference counter tracking. Report -EMFILE in case UINT_MAX is reached. nft_use_dec() splats in case that reference counter underflows, which should not ever happen. Add nft_use_inc_restore() and nft_use_dec_restore() which are used to restore reference counter from error and abort paths. Use u32 in nft_flowtable and nft_object since helper functions cannot work on bitfields. Remove the few early incomplete checks now that the helper functions are in place and used to check for refcount overflow. Fixes: 96518518cc41 ("netfilter: add nftables") Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: nf_tables: reject unbound anonymous set before commit phase

2023-06-20T20:43:41+00:00

Add a new list to track set transaction and to check for unbound anonymous sets before entering the commit phase. Bail out at the end of the transaction handling if an anonymous set remains unbound. Fixes: 96518518cc41 ("netfilter: add nftables") Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: drop map element references from preparation phase

2023-06-20T20:43:40+00:00

set .destroy callback releases the references to other objects in maps. This is very late and it results in spurious EBUSY errors. Drop refcount from the preparation phase instead, update set backend not to drop reference counter from set .destroy path. Exceptions: NFT_TRANS_PREPARE_ERROR does not require to drop the reference counter because the transaction abort path releases the map references for each element since the set is unbound. The abort path also deals with releasing reference counter for new elements added to unbound sets. Fixes: 591054469b3e ("netfilter: nf_tables: revisit chain/object refcounting from elements") Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: add NFT_TRANS_PREPARE_ERROR to deal with bound set/chain

2023-06-20T20:43:40+00:00

Add a new state to deal with rule expressions deactivation from the newrule error path, otherwise the anonymous set remains in the list in inactive state for the next generation. Mark the set/chain transaction as unbound so the abort path releases this object, set it as inactive in the next generation so it is not reachable anymore from this transaction and reference counter is dropped. Fixes: 1240eb93f061 ("netfilter: nf_tables: incorrect error path handling with NFT_MSG_NEWRULE") Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: fix chain binding transaction logic

2023-06-20T20:41:51+00:00

Add bound flag to rule and chain transactions as in 6a0a8d10a366 ("netfilter: nf_tables: use-after-free in failing rule with bound set") to skip them in case that the chain is already bound from the abort path. This patch fixes an imbalance in the chain use refcnt that triggers a WARN_ON on the table and chain destroy path. This patch also disallows nested chain bindings, which is not supported from userspace. The logic to deal with chain binding in nft_data_hold() and nft_data_release() is not correct. The NFT_TRANS_PREPARE state needs a special handling in case a chain is bound but next expressions in the same rule fail to initialize as described by 1240eb93f061 ("netfilter: nf_tables: incorrect error path handling with NFT_MSG_NEWRULE"). The chain is left bound if rule construction fails, so the objects stored in this chain (and the chain itself) are released by the transaction records from the abort path, follow up patch ("netfilter: nf_tables: add NFT_TRANS_PREPARE_ERROR to deal with bound set/chain") completes this error handling. When deleting an existing rule, chain bound flag is set off so the rule expression .destroy path releases the objects. Fixes: d0e2c7de92c7 ("netfilter: nf_tables: add NFT_CHAIN_BINDING") Signed-off-by: Pablo Neira Ayuso

net/sched: act_ct: Fix promotion of offloaded unreplied tuple

2023-06-14T07:56:50+00:00

Currently UNREPLIED and UNASSURED connections are added to the nf flow table. This causes the following connection packets to be processed by the flow table which then skips conntrack_in(), and thus such the connections will remain UNREPLIED and UNASSURED even if reply traffic is then seen. Even still, the unoffloaded reply packets are the ones triggering hardware update from new to established state, and if there aren't any to triger an update and/or previous update was missed, hardware can get out of sync with sw and still mark packets as new. Fix the above by: 1) Not skipping conntrack_in() for UNASSURED packets, but still refresh for hardware, as before the cited patch. 2) Try and force a refresh by reply-direction packets that update the hardware rules from new to established state. 3) Remove any bidirectional flows that didn't failed to update in hardware for re-insertion as bidrectional once any new packet arrives. Fixes: 6a9bad0069cf ("net/sched: act_ct: offload UDP NEW connections") Co-developed-by: Vlad Buslov Signed-off-by: Vlad Buslov Signed-off-by: Paul Blakey Reviewed-by: Florian Westphal Link: https://lore.kernel.org/r/1686313379-117663-1-git-send-email-paulb@nvidia.com Signed-off-by: Paolo Abeni

netfilter: nf_tables: integrate pipapo into commit protocol

2023-06-08T01:56:20+00:00

The pipapo set backend follows copy-on-update approach, maintaining one clone of the existing datastructure that is being updated. The clone and current datastructures are swapped via rcu from the commit step. The existing integration with the commit protocol is flawed because there is no operation to clean up the clone if the transaction is aborted. Moreover, the datastructure swap happens on set element activation. This patch adds two new operations for sets: commit and abort, these new operations are invoked from the commit and abort steps, after the transactions have been digested, and it updates the pipapo set backend to use it. This patch adds a new ->pending_update field to sets to maintain a list of sets that require this new commit and abort operations. Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges") Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: deactivate anonymous set from preparation phase

2023-05-03T06:24:32+00:00

Toggle deleted anonymous sets as inactive in the next generation, so users cannot perform any update on it. Clear the generation bitmask in case the transaction is aborted. The following KASAN splat shows a set element deletion for a bound anonymous set that has been already removed in the same transaction. [ 64.921510] ================================================================== [ 64.923123] BUG: KASAN: wild-memory-access in nf_tables_commit+0xa24/0x1490 [nf_tables] [ 64.924745] Write of size 8 at addr dead000000000122 by task test/890 [ 64.927903] CPU: 3 PID: 890 Comm: test Not tainted 6.3.0+ #253 [ 64.931120] Call Trace: [ 64.932699] [ 64.934292] dump_stack_lvl+0x33/0x50 [ 64.935908] ? nf_tables_commit+0xa24/0x1490 [nf_tables] [ 64.937551] kasan_report+0xda/0x120 [ 64.939186] ? nf_tables_commit+0xa24/0x1490 [nf_tables] [ 64.940814] nf_tables_commit+0xa24/0x1490 [nf_tables] [ 64.942452] ? __kasan_slab_alloc+0x2d/0x60 [ 64.944070] ? nf_tables_setelem_notify+0x190/0x190 [nf_tables] [ 64.945710] ? kasan_set_track+0x21/0x30 [ 64.947323] nfnetlink_rcv_batch+0x709/0xd90 [nfnetlink] [ 64.948898] ? nfnetlink_rcv_msg+0x480/0x480 [nfnetlink] Signed-off-by: Pablo Neira Ayuso