kernel/include/net/net_namespace.h, branch linux-4.19.y

netns: add pre_exit method to struct pernet_operations

2024-09-12T09:02:55Z

commit d7d99872c144a2c2f5d9c9d83627fa833836cba5 upstream. Current struct pernet_operations exit() handlers are highly discouraged to call synchronize_rcu(). There are cases where we need them, and exit_batch() does not help the common case where a single netns is dismantled. This patch leverages the existing synchronize_rcu() call in cleanup_net() Calling optional ->pre_exit() method before ->exit() or ->exit_batch() allows to benefit from a single synchronize_rcu() call. Note that the synchronize_rcu() calls added in this patch are only in error paths or slow paths. Tested: $ time for i in {1..1000}; do unshare -n /bin/false;done real 0m2.612s user 0m0.171s sys 0m2.216s Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: make get_net_ns return error if NET_NS is disabled

2021-06-30T12:48:18Z

[ Upstream commit ea6932d70e223e02fea3ae20a4feff05d7c1ea9a ] There is a panic in socket ioctl cmd SIOCGSKNS when NET_NS is not enabled. The reason is that nsfs tries to access ns->ops but the proc_ns_operations is not implemented in this case. [7.670023] Unable to handle kernel NULL pointer dereference at virtual address 00000010 [7.670268] pgd = 32b54000 [7.670544] [00000010] *pgd=00000000 [7.671861] Internal error: Oops: 5 [#1] SMP ARM [7.672315] Modules linked in: [7.672918] CPU: 0 PID: 1 Comm: systemd Not tainted 5.13.0-rc3-00375-g6799d4f2da49 #16 [7.673309] Hardware name: Generic DT based system [7.673642] PC is at nsfs_evict+0x24/0x30 [7.674486] LR is at clear_inode+0x20/0x9c The same to tun SIOCGSKNS command. To fix this problem, we make get_net_ns() return -EINVAL when NET_NS is disabled. Meanwhile move it to right place net/core/net_namespace.c. Signed-off-by: Changbin Du Fixes: c62cce2caee5 ("net: add an ioctl to get a socket network namespace") Cc: Cong Wang Cc: Jakub Kicinski Cc: David Laight Cc: Christian Brauner Suggested-by: Jakub Kicinski Acked-by: Christian Brauner Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

netns: fix GFP flags in rtnl_net_notifyid()

2019-11-10T10:27:42Z

[ Upstream commit d4e4fdf9e4a27c87edb79b1478955075be141f67 ] In rtnl_net_notifyid(), we certainly can't pass a null GFP flag to rtnl_notify(). A GFP_KERNEL flag would be fine in most circumstances, but there are a few paths calling rtnl_net_notifyid() from atomic context or from RCU critical sections. The later also precludes the use of gfp_any() as it wouldn't detect the RCU case. Also, the nlmsg_new() call is wrong too, as it uses GFP_KERNEL unconditionally. Therefore, we need to pass the GFP flags as parameter and propagate it through function calls until the proper flags can be determined. In most cases, GFP_KERNEL is fine. The exceptions are: * openvswitch: ovs_vport_cmd_get() and ovs_vport_cmd_dump() indirectly call rtnl_net_notifyid() from RCU critical section, * rtnetlink: rtmsg_ifinfo_build_skb() already receives GFP flags as parameter. Also, in ovs_vport_cmd_build_info(), let's change the GFP flags used by nlmsg_new(). The function is allowed to sleep, so better make the flags consistent with the ones used in the following ovs_vport_cmd_fill_info() call. Found by code inspection. Fixes: 9a9634545c70 ("netns: notify netns id events") Signed-off-by: Guillaume Nault Acked-by: Nicolas Dichtel Acked-by: Pravin B Shelar Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

netns: provide pure entropy for net_hash_mix()

2019-04-17T06:38:40Z

[ 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: Sasha Levin

net: create reusable function for getting ownership info of sysfs inodes

2018-07-21T06:44:36Z

Make net_ns_get_ownership() reusable by networking code outside of core. This is useful, for example, to allow bridge related sysfs files to be owned by container root. Add a function comment since this is a potentially dangerous function to use given the way that kobject_get_ownership() works by initializing uid and gid before calling .get_ownership(). Signed-off-by: Tyler Hicks Signed-off-by: David S. Miller

netfilter: ipv6: nf_defrag: reduce struct net memory waste

2018-06-18T12:13:25Z

It is a waste of memory to use a full "struct netns_sysctl_ipv6" while only one pointer is really used, considering netns_sysctl_ipv6 keeps growing. Also, since "struct netns_frags" has cache line alignment, it is better to move the frags_hdr pointer outside, otherwise we spend a full cache line for this pointer. This saves 192 bytes of memory per netns. Fixes: c038a767cd69 ("ipv6: add a new namespace for nf_conntrack_reasm") Signed-off-by: Eric Dumazet Signed-off-by: Pablo Neira Ayuso

net: Introduce net_rwsem to protect net_namespace_list

2018-03-29T17:47:53Z

rtnl_lock() is used everywhere, and contention is very high. When someone wants to iterate over alive net namespaces, he/she has no a possibility to do that without exclusive lock. But the exclusive rtnl_lock() in such places is overkill, and it just increases the contention. Yes, there is already for_each_net_rcu() in kernel, but it requires rcu_read_lock(), and this can't be sleepable. Also, sometimes it may be need really prevent net_namespace_list growth, so for_each_net_rcu() is not fit there. This patch introduces new rw_semaphore, which will be used instead of rtnl_mutex to protect net_namespace_list. It is sleepable and allows not-exclusive iterations over net namespaces list. It allows to stop using rtnl_lock() in several places (what is made in next patches) and makes less the time, we keep rtnl_mutex. Here we just add new lock, while the explanation of we can remove rtnl_lock() there are in next patches. Fine grained locks generally are better, then one big lock, so let's do that with net_namespace_list, while the situation allows that. Signed-off-by: Kirill Tkhai Signed-off-by: David S. Miller

net: Add more comments

2018-03-27T17:18:09Z

This adds comments to different places to improve readability. Signed-off-by: Kirill Tkhai Signed-off-by: David S. Miller

net: Rename net_sem to pernet_ops_rwsem

2018-03-27T17:18:09Z

net_sem is some undefined area name, so it will be better to make the area more defined. Rename it to pernet_ops_rwsem for better readability and better intelligibility. Signed-off-by: Kirill Tkhai Signed-off-by: David S. Miller

net: Drop pernet_operations::async

2018-03-27T17:18:09Z

Synchronous pernet_operations are not allowed anymore. All are asynchronous. So, drop the structure member. Signed-off-by: Kirill Tkhai Signed-off-by: David S. Miller