kernel/linux.git/include/net/net_namespace.h, branch v6.19.11

Merge tag 'namespace-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-09-29T18:20:29+00:00

Pull namespace updates from Christian Brauner: "This contains a larger set of changes around the generic namespace infrastructure of the kernel. Each specific namespace type (net, cgroup, mnt, ...) embedds a struct ns_common which carries the reference count of the namespace and so on. We open-coded and cargo-culted so many quirks for each namespace type that it just wasn't scalable anymore. So given there's a bunch of new changes coming in that area I've started cleaning all of this up. The core change is to make it possible to correctly initialize every namespace uniformly and derive the correct initialization settings from the type of the namespace such as namespace operations, namespace type and so on. This leaves the new ns_common_init() function with a single parameter which is the specific namespace type which derives the correct parameters statically. This also means the compiler will yell as soon as someone does something remotely fishy. The ns_common_init() addition also allows us to remove ns_alloc_inum() and drops any special-casing of the initial network namespace in the network namespace initialization code that Linus complained about. Another part is reworking the reference counting. The reference counting was open-coded and copy-pasted for each namespace type even though they all followed the same rules. This also removes all open accesses to the reference count and makes it private and only uses a very small set of dedicated helpers to manipulate them just like we do for e.g., files. In addition this generalizes the mount namespace iteration infrastructure introduced a few cycles ago. As reminder, the vfs makes it possible to iterate sequentially and bidirectionally through all mount namespaces on the system or all mount namespaces that the caller holds privilege over. This allow userspace to iterate over all mounts in all mount namespaces using the listmount() and statmount() system call. Each mount namespace has a unique identifier for the lifetime of the systems that is exposed to userspace. The network namespace also has a unique identifier working exactly the same way. This extends the concept to all other namespace types. The new nstree type makes it possible to lookup namespaces purely by their identifier and to walk the namespace list sequentially and bidirectionally for all namespace types, allowing userspace to iterate through all namespaces. Looking up namespaces in the namespace tree works completely locklessly. This also means we can move the mount namespace onto the generic infrastructure and remove a bunch of code and members from struct mnt_namespace itself. There's a bunch of stuff coming on top of this in the future but for now this uses the generic namespace tree to extend a concept introduced first for pidfs a few cycles ago. For a while now we have supported pidfs file handles for pidfds. This has proven to be very useful. This extends the concept to cover namespaces as well. It is possible to encode and decode namespace file handles using the common name_to_handle_at() and open_by_handle_at() apis. As with pidfs file handles, namespace file handles are exhaustive, meaning it is not required to actually hold a reference to nsfs in able to decode aka open_by_handle_at() a namespace file handle. Instead the FD_NSFS_ROOT constant can be passed which will let the kernel grab a reference to the root of nsfs internally and thus decode the file handle. Namespaces file descriptors can already be derived from pidfds which means they aren't subject to overmount protection bugs. IOW, it's irrelevant if the caller would not have access to an appropriate /proc//ns/ directory as they could always just derive the namespace based on a pidfd already. It has the same advantage as pidfds. It's possible to reliably and for the lifetime of the system refer to a namespace without pinning any resources and to compare them trivially. Permission checking is kept simple. If the caller is located in the namespace the file handle refers to they are able to open it otherwise they must hold privilege over the owning namespace of the relevant namespace. The namespace file handle layout is exposed as uapi and has a stable and extensible format. For now it simply contains the namespace identifier, the namespace type, and the inode number. The stable format means that userspace may construct its own namespace file handles without going through name_to_handle_at() as they are already allowed for pidfs and cgroup file handles" * tag 'namespace-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (65 commits) ns: drop assert ns: move ns type into struct ns_common nstree: make struct ns_tree private ns: add ns_debug() ns: simplify ns_common_init() further cgroup: add missing ns_common include ns: use inode initializer for initial namespaces selftests/namespaces: verify initial namespace inode numbers ns: rename to __ns_ref nsfs: port to ns_ref_*() helpers net: port to ns_ref_*() helpers uts: port to ns_ref_*() helpers ipv4: use check_net() net: use check_net() net-sysfs: use check_net() user: port to ns_ref_*() helpers time: port to ns_ref_*() helpers pid: port to ns_ref_*() helpers ipc: port to ns_ref_*() helpers cgroup: port to ns_ref_*() helpers ...

net: port to ns_ref_*() helpers

2025-09-19T14:22:38+00:00

Stop accessing ns.count directly. Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

ns: add to__ns() to respective headers

2025-09-19T12:26:16+00:00

Every namespace type has a container_of(ns, , ns) static inline function that is currently not exposed in the header. So we have a bunch of places that open-code it via container_of(). Move it to the headers so we can use it directly. Reviewed-by: Aleksa Sarai Signed-off-by: Christian Brauner

copy_process: pass clone_flags as u64 across calltree

2025-09-01T13:31:34+00:00

With the introduction of clone3 in commit 7f192e3cd316 ("fork: add clone3") the effective bit width of clone_flags on all architectures was increased from 32-bit to 64-bit, with a new type of u64 for the flags. However, for most consumers of clone_flags the interface was not changed from the previous type of unsigned long. While this works fine as long as none of the new 64-bit flag bits (CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still undesirable in terms of the principle of least surprise. Thus, this commit fixes all relevant interfaces of callees to sys_clone3/copy_process (excluding the architecture-specific copy_thread) to consistently pass clone_flags as u64, so that no truncation to 32-bit integers occurs on 32-bit architectures. Signed-off-by: Simon Schuster Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-2-53fcf5577d57@siemens-energy.com Acked-by: David Hildenbrand Reviewed-by: Lorenzo Stoakes Reviewed-by: Arnd Bergmann Signed-off-by: Christian Brauner

net: Remove ->exit_batch_rtnl().

2025-04-15T00:08:45+00:00

There are no ->exit_batch_rtnl() users remaining. Let's remove the hook. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20250411205258.63164-15-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

net: Add ->exit_rtnl() hook to struct pernet_operations.

2025-04-15T00:08:41+00:00

struct pernet_operations provides two batching hooks; ->exit_batch() and ->exit_batch_rtnl(). The batching variant is beneficial if ->exit() meets any of the following conditions: 1) ->exit() repeatedly acquires a global lock for each netns 2) ->exit() has a time-consuming operation that can be factored out (e.g. synchronize_rcu(), smp_mb(), etc) 3) ->exit() does not need to repeat the same iterations for each netns (e.g. inet_twsk_purge()) Currently, none of the ->exit_batch_rtnl() functions satisfy any of the above conditions because RTNL is factored out and held by the caller and all of these functions iterate over the dying netns list. Also, we want to hold per-netns RTNL there but avoid spreading __rtnl_net_lock() across multiple locations. Let's add ->exit_rtnl() hook and run it under __rtnl_net_lock(). The following patches will convert all ->exit_batch_rtnl() users to ->exit_rtnl(). Signed-off-by: Kuniyuki Iwashima Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20250411205258.63164-4-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

net: introduce per netns packet chains

2025-03-24T20:58:22+00:00

Currently network taps unbound to any interface are linked in the global ptype_all list, affecting the performance in all the network namespaces. Add per netns ptypes chains, so that in the mentioned case only the netns owning the packet socket(s) is affected. While at that drop the global ptype_all list: no in kernel user registers a tap on "any" type without specifying either the target device or the target namespace (and IMHO doing that would not make any sense). Note that this adds a conditional in the fast path (to check for per netns ptype_specific list) and increases the dataset size by a cacheline (owing the per netns lists). Reviewed-by: Sabrina Dubroca Signed-off-by: Paolo Abeni Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/ae405f98875ee87f8150c460ad162de7e466f8a7.1742494826.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski

net: Add net_passive_inc() and net_passive_dec().

2025-02-19T02:33:29+00:00

net_drop_ns() is NULL when CONFIG_NET_NS is disabled. The next patch introduces a function that increments and decrements net->passive. As a prep, let's rename and export net_free() to net_passive_dec() and add net_passive_inc(). Suggested-by: Eric Dumazet Link: https://lore.kernel.org/netdev/CANn89i+oUCt2VGvrbrweniTendZFEh+nwS=uonc004-aPkWy-Q@mail.gmail.com/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250217191129.19967-2-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

net: add dev_net_rcu() helper

2025-02-07T00:14:14+00:00

dev->nd_net can change, readers should either use rcu_read_lock() or RTNL. We currently use a generic helper, dev_net() with no debugging support. We probably have many hidden bugs. Add dev_net_rcu() helper for callers using rcu_read_lock() protection. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250205155120.1676781-2-edumazet@google.com Signed-off-by: Jakub Kicinski

net: expedite synchronize_net() for cleanup_net()

2025-01-16T03:17:03+00:00

cleanup_net() is the single thread responsible for netns dismantles, and a serious bottleneck. Before we can get per-netns RTNL, make sure all synchronize_net() called from this thread are using rcu_synchronize_expedited(). v3: deal with CONFIG_NET_NS=n Signed-off-by: Eric Dumazet Reviewed-by: Jesse Brandeburg Link: https://patch.msgid.link/20250114205531.967841-2-edumazet@google.com Signed-off-by: Jakub Kicinski