kernel.git/net/core/net_namespace.c, branch linux-4.4.y

netns: add schedule point in ops_exit_list()

2022-01-27T07:46:20Z

commit 2836615aa22de55b8fca5e32fe1b27a67cda625e upstream. When under stress, cleanup_net() can have to dismantle netns in big numbers. ops_exit_list() currently calls many helpers [1] that have no schedule point, and we can end up with soft lockups, particularly on hosts with many cpus. Even for moderate amount of netns processed by cleanup_net() this patch avoids latency spikes. [1] Some of these helpers like fib_sync_up() and fib_sync_down_dev() are very slow because net/ipv4/fib_semantics.c uses host-wide hash tables, and ifindex is used as the only input of two hash functions. ifindexes tend to be the same for all netns (lo.ifindex==1 per instance) This will be fixed in a separate patch. Fixes: 72ad937abd0a ("net: Add support for batching network namespace cleanups") Signed-off-by: Eric Dumazet Cc: Eric W. Biederman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net/net_namespace: Check the return value of register_pernet_subsys()

2019-12-05T14:27:01Z

[ Upstream commit 0eb987c874dc93f9c9d85a6465dbde20fdd3884c ] In net_ns_init(), register_pernet_subsys() could fail while registering network namespace subsystems. The fix checks the return value and sends a panic() on failure. Signed-off-by: Aditya Pakki Reviewed-by: Kirill Tkhai Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

netns: provide pure entropy for net_hash_mix()

2019-04-27T07:33:55Z

[ Upstream commit 355b98553789b646ed97ad801a619ff898471b92 ] net_hash_mix() currently uses kernel address of a struct net, and is used in many places that could be used to reveal this address to a patient attacker, thus defeating KASLR, for the typical case (initial net namespace, &init_net is not dynamically allocated) I believe the original implementation tried to avoid spending too many cycles in this function, but security comes first. Also provide entropy regardless of CONFIG_NET_NS. Fixes: 0b4419162aa6 ("netns: introduce the net_hash_mix "salt" for hashes") Signed-off-by: Eric Dumazet Reported-by: Amit Klein Reported-by: Benny Pinkas Cc: Pavel Emelyanov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: move somaxconn init from sysctl code

2018-04-13T17:50:11Z

[ Upstream commit 7c3f1875c66fbc19762760097cabc91849ea0bbb ] The default value for somaxconn is set in sysctl_core_net_init(), but this function is not called when kernel is configured without CONFIG_SYSCTL. This results in the kernel not being able to accept TCP connections, because the backlog has zero size. Usually, the user ends up with: "TCP: request_sock_TCP: Possible SYN flooding on port 7. Dropping request. Check SNMP counters." If SYN cookies are not enabled the connection is rejected. Before ef547f2ac16 (tcp: remove max_qlen_log), the effects were less severe, because the backlog was always at least eight slots long. Signed-off-by: Roman Kapl Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net: Fix double free and memory corruption in get_net_ns_by_id()

2018-01-02T19:33:26Z

[ Upstream commit 21b5944350052d2583e82dd59b19a9ba94a007f0 ] (I can trivially verify that that idr_remove in cleanup_net happens after the network namespace count has dropped to zero --EWB) Function get_net_ns_by_id() does not check for net::count after it has found a peer in netns_ids idr. It may dereference a peer, after its count has already been finaly decremented. This leads to double free and memory corruption: put_net(peer) rtnl_lock() atomic_dec_and_test(&peer->count) [count=0] ... __put_net(peer) get_net_ns_by_id(net, id) spin_lock(&cleanup_list_lock) list_add(&net->cleanup_list, &cleanup_list) spin_unlock(&cleanup_list_lock) queue_work() peer = idr_find(&net->netns_ids, id) | get_net(peer) [count=1] | ... | (use after final put) v ... cleanup_net() ... spin_lock(&cleanup_list_lock) ... list_replace_init(&cleanup_list, ..) ... spin_unlock(&cleanup_list_lock) ... ... ... ... put_net(peer) ... atomic_dec_and_test(&peer->count) [count=0] ... spin_lock(&cleanup_list_lock) ... list_add(&net->cleanup_list, &cleanup_list) ... spin_unlock(&cleanup_list_lock) ... queue_work() ... rtnl_unlock() rtnl_lock() ... for_each_net(tmp) { ... id = __peernet2id(tmp, peer) ... spin_lock_irq(&tmp->nsid_lock) ... idr_remove(&tmp->netns_ids, id) ... ... ... net_drop_ns() ... net_free(peer) ... } ... | v cleanup_net() ... (Second free of peer) Also, put_net() on the right cpu may reorder with left's cpu list_replace_init(&cleanup_list, ..), and then cleanup_list will be corrupted. Since cleanup_net() is executed in worker thread, while put_net(peer) can happen everywhere, there should be enough time for concurrent get_net_ns_by_id() to pick the peer up, and the race does not seem to be unlikely. The patch fixes the problem in standard way. (Also, there is possible problem in peernet2id_alloc(), which requires check for net::count under nsid_lock and maybe_get_net(peer), but in current stable kernel it's used under rtnl_lock() and it has to be safe. Openswitch begun to use peernet2id_alloc(), and possibly it should be fixed too. While this is not in stable kernel yet, so I'll send a separate message to netdev@ later). Cc: Nicolas Dichtel Signed-off-by: Kirill Tkhai Fixes: 0c7aecd4bde4 "netns: add rtnl cmd to add and get peer netns ids" Reviewed-by: Andrey Ryabinin Reviewed-by: "Eric W. Biederman" Signed-off-by: Eric W. Biederman Reviewed-by: Eric Dumazet Acked-by: Nicolas Dichtel Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: check dead netns for peernet2id_alloc()

2016-12-10T18:07:22Z

[ Upstream commit cfc44a4d147ea605d66ccb917cc24467d15ff867 ] Andrei reports we still allocate netns ID from idr after we destroy it in cleanup_net(). cleanup_net(): ... idr_destroy(&net->netns_ids); ... list_for_each_entry_reverse(ops, &pernet_list, list) ops_exit_list(ops, &net_exit_list); -> rollback_registered_many() -> rtmsg_ifinfo_build_skb() -> rtnl_fill_ifinfo() -> peernet2id_alloc() After that point we should not even access net->netns_ids, we should check the death of the current netns as early as we can in peernet2id_alloc(). For net-next we can consider to avoid sending rtmsg totally, it is a good optimization for netns teardown path. Fixes: 0c7aecd4bde4 ("netns: add rtnl cmd to add and get peer netns ids") Reported-by: Andrei Vagin Cc: Nicolas Dichtel Signed-off-by: Cong Wang Acked-by: Andrei Vagin Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

netns: make nsid_lock per net

2015-05-18T03:41:11Z

The spinlock is used to protect netns_ids which is per net, so there is no need to use a global spinlock. Cc: Nicolas Dichtel Signed-off-by: Cong Wang Acked-by: Nicolas Dichtel Signed-off-by: David S. Miller

netns: fix unbalanced spin_lock on error

2015-05-15T02:36:31Z

Unlock was missing on error path. Fixes: 95f38411df05 ("netns: use a spin_lock to protect nsid management") Reported-by: Dan Carpenter Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller

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

2015-05-13T18:31:43Z

Four minor merge conflicts: 1) qca_spi.c renamed the local variable used for the SPI device from spi_device to spi, meanwhile the spi_set_drvdata() call got moved further up in the probe function. 2) Two changes were both adding new members to codel params structure, and thus we had overlapping changes to the initializer function. 3) 'net' was making a fix to sk_release_kernel() which is completely removed in 'net-next'. 4) In net_namespace.c, the rtnl_net_fill() call for GET operations had the command value fixed, meanwhile 'net-next' adjusted the argument signature a bit. This also matches example merge resolutions posted by Stephen Rothwell over the past two days. Signed-off-by: David S. Miller

netns: return RTM_NEWNSID instead of RTM_GETNSID on a get

2015-05-12T22:53:25Z

Usually, RTM_NEWxxx is returned on a get (same as a dump). Fixes: 0c7aecd4bde4 ("netns: add rtnl cmd to add and get peer netns ids") Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller