linux/net/netfilter/nf_queue.c, branch v6.3

netfilter: nf_queue: handle socket prefetch

2022-03-01T10:51:15Z

In case someone combines bpf socket assign and nf_queue, then we will queue an skb who references a struct sock that did not have its reference count incremented. As we leave rcu protection, there is no guarantee that skb->sk is still valid. For refcount-less skb->sk case, try to increment the reference count and then override the destructor. In case of failure we have two choices: orphan the skb and 'delete' preselect or let nf_queue() drop the packet. Do the latter, it should not happen during normal operation. Fixes: cf7fbe660f2d ("bpf: Add socket assign support") Acked-by: Joe Stringer Signed-off-by: Florian Westphal

netfilter: nf_queue: fix possible use-after-free

2022-03-01T10:50:35Z

Eric Dumazet says: The sock_hold() side seems suspect, because there is no guarantee that sk_refcnt is not already 0. On failure, we cannot queue the packet and need to indicate an error. The packet will be dropped by the caller. v2: split skb prefetch hunk into separate change Fixes: 271b72c7fa82c ("udp: RCU handling for Unicast packets.") Reported-by: Eric Dumazet Reviewed-by: Eric Dumazet Signed-off-by: Florian Westphal

netfilter: nf_queue: don't assume sk is full socket

2022-03-01T10:48:18Z

There is no guarantee that state->sk refers to a full socket. If refcount transitions to 0, sock_put calls sk_free which then ends up with garbage fields. I'd like to thank Oleksandr Natalenko and Jiri Benc for considerable debug work and pointing out state->sk oddities. Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener") Tested-by: Oleksandr Natalenko Signed-off-by: Florian Westphal

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

2021-08-11T09:22:26Z

Pablo Neira Ayuso says: ==================== Netfilter updates for net-next The following patchset contains Netfilter updates for net-next: 1) Use nfnetlink_unicast() instead of netlink_unicast() in nft_compat. 2) Remove call to nf_ct_l4proto_find() in flowtable offload timeout fixup. 3) CLUSTERIP registers ARP hook on demand, from Florian. 4) Use clusterip_net to store pernet warning, also from Florian. 5) Remove struct netns_xt, from Florian Westphal. 6) Enable ebtables hooks in initns on demand, from Florian. 7) Allow to filter conntrack netlink dump per status bits, from Florian Westphal. 8) Register x_tables hooks in initns on demand, from Florian. 9) Remove queue_handler from per-netns structure, again from Florian. ==================== Signed-off-by: David S. Miller

netfilter: nf_queue: move hookfn registration out of struct net

2021-08-10T15:32:00Z

This was done to detect when the pernet->init() function was not called yet, by checking if net->nf.queue_handler is NULL. Once the nfnetlink_queue module is active, all struct net pointers contain the same address. So place this back in nf_queue.c. Handle the 'netns error unwind' test by checking nfnl_queue_net for a NULL pointer and add a comment for this. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

net: Remove redundant if statements

2021-08-05T12:27:50Z

The 'if (dev)' statement already move into dev_{put , hold}, so remove redundant if statements. Signed-off-by: Yajun Deng Signed-off-by: David S. Miller

netfilter: nf_queue: prefer nf_queue_entry_free

2020-03-29T14:28:29Z

Instead of dropping refs+kfree, use the helper added in previous patch. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_queue: do not release refcouts until nf_reinject is done

2020-03-29T14:28:29Z

nf_queue is problematic when another NF_QUEUE invocation happens from nf_reinject(). 1. nf_queue is invoked, increments state->sk refcount. 2. skb is queued, waiting for verdict. 3. sk is closed/released. 3. verdict comes back, nf_reinject is called. 4. nf_reinject drops the reference -- refcount can now drop to 0 Instead of get_ref/release_ref pattern, we need to nest the get_ref calls: get_ref get_ref release_ref release_ref So that when we invoke the next processing stage (another netfilter or the okfn()), we hold at least one reference count on the devices/socket. After previous patch, it is now safe to put the entry even after okfn() has potentially free'd the skb. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_queue: place bridge physports into queue_entry struct

2020-03-29T14:28:29Z

The refcount is done via entry->skb, which does work fine. Major problem: When putting the refcount of the bridge ports, we must always put the references while the skb is still around. However, we will need to put the references after okfn() to avoid a possible 1 -> 0 -> 1 refcount transition, so we cannot use the skb pointer anymore. Place the physports in the queue entry structure instead to allow for refcounting changes in the next patch. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_queue: make nf_queue_entry_release_refs static

2020-03-29T14:28:29Z

This is a preparation patch, no logical changes. Move free_entry into core and rename it to something more sensible. Will ease followup patches which will complicate the refcount handling. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso