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Add a regression test for setns() with pidfd.
Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-7-ae8a4ad5a3b3@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add a few more assert to detect active reference count underflows.
Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-6-ae8a4ad5a3b3@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The setns() system call supports:
(1) namespace file descriptors (nsfd)
(2) process file descriptors (pidfd)
When using nsfds the namespaces will remain active because they are
pinned by the vfs. However, when pidfds are used things are more
complicated.
When the target task exits and passes through exit_nsproxy_namespaces()
or is reaped and thus also passes through exit_cred_namespaces() after
the setns()'ing task has called prepare_nsset() but before the active
reference count of the set of namespaces it wants to setns() to might
have been dropped already:
P1 P2
pid_p1 = clone(CLONE_NEWUSER | CLONE_NEWNET | CLONE_NEWNS)
pidfd = pidfd_open(pid_p1)
setns(pidfd, CLONE_NEWUSER | CLONE_NEWNET | CLONE_NEWNS)
prepare_nsset()
exit(0)
// ns->__ns_active_ref == 1
// parent_ns->__ns_active_ref == 1
-> exit_nsproxy_namespaces()
-> exit_cred_namespaces()
// ns_active_ref_put() will also put
// the reference on the owner of the
// namespace. If the only reason the
// owning namespace was alive was
// because it was a parent of @ns
// it's active reference count now goes
// to zero... --------------------------------
// |
// ns->__ns_active_ref == 0 |
// parent_ns->__ns_active_ref == 0 |
| commit_nsset()
-----------------> // If setns()
// now manages to install the namespaces
// it will call ns_active_ref_get()
// on them thus bumping the active reference
// count from zero again but without also
// taking the required reference on the owner.
// Thus we get:
//
// ns->__ns_active_ref == 1
// parent_ns->__ns_active_ref == 0
When later someone does ns_active_ref_put() on @ns it will underflow
parent_ns->__ns_active_ref leading to a splat from our asserts
thinking there are still active references when in fact the counter
just underflowed.
So resurrect the ownership chain if necessary as well. If the caller
succeeded to grab passive references to the set of namespaces the
setns() should simply succeed even if the target task exists or gets
reaped in the meantime and thus has dropped all active references to its
namespaces.
The race is rare and can only be triggered when using pidfs to setns()
to namespaces. Also note that active reference on initial namespaces are
nops.
Since we now always handle parent references directly we can drop
ns_ref_active_get_owner() when adding a namespace to a namespace tree.
This is now all handled uniformly in the places where the new namespaces
actually become active.
Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-5-ae8a4ad5a3b3@kernel.org
Fixes: 3c9820d5c64a ("ns: add active reference count")
Reported-by: syzbot+1957b26299cf3ff7890c@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Don't return EINVAL, return EFAULT just like we do in other system
calls.
Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-4-ae8a4ad5a3b3@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The mount namespace may in fact sleep when putting the last passive
reference so we need to drop the namespace reference outside of the rcu
read lock. Do this by delaying the put until the next iteration where
we've already moved on to the next namespace and legitimized it. Once we
drop the rcu read lock to call put_user() we will also drop the
reference to the previous namespace in the tree.
Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-3-ae8a4ad5a3b3@kernel.org
Fixes: 76b6f5dfb3fd ("nstree: add listns()")
Signed-off-by: Christian Brauner <brauner@kernel.org>
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There's no need to bump the active reference counts of initial
namespaces as they're always active and can simply remain at 1.
Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-2-ae8a4ad5a3b3@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Don't skip active reference count initialization for initial namespaces.
Doing this will break network namespace active reference counting.
Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-1-ae8a4ad5a3b3@kernel.org
Fixes: 3a18f809184b ("ns: add active reference count")
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Christian Brauner <brauner@kernel.org> says:
As announced a while ago this is the next step building on the nstree
work from prior cycles. There's a bunch of fixes and semantic cleanups
in here and a ton of tests.
Currently listns() is relying on active namespace reference counts which
are introduced alongside this series.
While a namespace is on the namespace trees with a valid reference count
it is possible to reopen it through a namespace file handle. This is all
fine but has some issues that should be addressed.
On current kernels a namespace is visible to userspace in the
following cases:
(1) The namespace is in use by a task.
(2) The namespace is persisted through a VFS object (namespace file
descriptor or bind-mount).
Note that (2) only cares about direct persistence of the namespace
itself not indirectly via e.g., file->f_cred file references or
similar.
(3) The namespace is a hierarchical namespace type and is the parent of
a single or multiple child namespaces.
Case (3) is interesting because it is possible that a parent namespace
might not fulfill any of (1) or (2), i.e., is invisible to userspace but
it may still be resurrected through the NS_GET_PARENT ioctl().
Currently namespace file handles allow much broader access to namespaces
than what is currently possible via (1)-(3). The reason is that
namespaces may remain pinned for completely internal reasons yet are
inaccessible to userspace.
For example, a user namespace my remain pinned by get_cred() calls to
stash the opener's credentials into file->f_cred. As it stands file
handles allow to resurrect such a users namespace even though this
should not be possible via (1)-(3). This is a fundamental uapi change
that we shouldn't do if we don't have to.
Consider the following insane case: Various architectures support the
CONFIG_MMU_LAZY_TLB_REFCOUNT option which uses lazy TLB destruction.
When this option is set a userspace task's struct mm_struct may be used
for kernel threads such as the idle task and will only be destroyed once
the cpu's runqueue switches back to another task. But because of ptrace()
permission checks struct mm_struct stashes the user namespace of the
task that struct mm_struct originally belonged to. The kernel thread
will take a reference on the struct mm_struct and thus pin it.
So on an idle system user namespaces can be persisted for arbitrary
amounts of time which also means that they can be resurrected using
namespace file handles. That makes no sense whatsoever. The problem is
of course excarabted on large systems with a huge number of cpus.
To handle this nicely we introduce an active reference count which
tracks (1)-(3). This is easy to do as all of these things are already
managed centrally. Only (1)-(3) will count towards the active reference
count and only namespaces which are active may be opened via namespace
file handles.
The problem is that namespaces may be resurrected. Which means that they
can become temporarily inactive and will be reactived some time later.
Currently the only example of this is the SIOGCSKNS socket ioctl. The
SIOCGSKNS ioctl allows to open a network namespace file descriptor based
on a socket file descriptor.
If a socket is tied to a network namespace that subsequently becomes
inactive but that socket is persisted by another process in another
network namespace (e.g., via SCM_RIGHTS of pidfd_getfd()) then the
SIOCGSKNS ioctl will resurrect this network namespace.
So calls to open_related_ns() and open_namespace() will end up
resurrecting the corresponding namespace tree.
Note that the active reference count does not regulate the lifetime of
the namespace itself. This is still done by the normal reference count.
The active reference count can only be elevated if the regular reference
count is elevated.
The active reference count also doesn't regulate the presence of a
namespace on the namespace trees. It only regulates its visiblity to
namespace file handles (and in later patches to listns()).
A namespace remains on the namespace trees from creation until its
actual destruction. This will allow the kernel to always reach any
namespace trivially and it will also enable subsystems like bpf to walk
the namespace lists on the system for tracing or general introspection
purposes.
Note that different namespaces have different visibility lifetimes on
current kernels. While most namespace are immediately released when the
last task using them exits, the user- and pid namespace are persisted
and thus both remain accessible via /proc/<pid>/ns/<ns_type>.
The user namespace lifetime is aliged with struct cred and is only
released through exit_creds(). However, it becomes inaccessible to
userspace once the last task using it is reaped, i.e., when
release_task() is called and all proc entries are flushed. Similarly,
the pid namespace is also visible until the last task using it has been
reaped and the associated pid numbers are freed.
The active reference counts of the user- and pid namespace are
decremented once the task is reaped.
Based on the namespace trees and the active reference count, a new
listns() system call that allows userspace to iterate through namespaces
in the system. This provides a programmatic interface to discover and
inspect namespaces, enhancing existing namespace apis.
Currently, there is no direct way for userspace to enumerate namespaces
in the system. Applications must resort to scanning /proc/<pid>/ns/
across all processes, which is:
1. Inefficient - requires iterating over all processes
2. Incomplete - misses inactive namespaces that aren't attached to any
running process but are kept alive by file descriptors, bind mounts,
or parent namespace references
3. Permission-heavy - requires access to /proc for many processes
4. No ordering or ownership.
5. No filtering per namespace type: Must always iterate and check all
namespaces.
The list goes on. The listns() system call solves these problems by
providing direct kernel-level enumeration of namespaces. It is similar
to listmount() but obviously tailored to namespaces.
/*
* @req: Pointer to struct ns_id_req specifying search parameters
* @ns_ids: User buffer to receive namespace IDs
* @nr_ns_ids: Size of ns_ids buffer (maximum number of IDs to return)
* @flags: Reserved for future use (must be 0)
*/
ssize_t listns(const struct ns_id_req *req, u64 *ns_ids,
size_t nr_ns_ids, unsigned int flags);
Returns:
- On success: Number of namespace IDs written to ns_ids
- On error: Negative error code
/*
* @size: Structure size
* @ns_id: Starting point for iteration; use 0 for first call, then
* use the last returned ID for subsequent calls to paginate
* @ns_type: Bitmask of namespace types to include (from enum ns_type):
* 0: Return all namespace types
* MNT_NS: Mount namespaces
* NET_NS: Network namespaces
* USER_NS: User namespaces
* etc. Can be OR'd together
* @user_ns_id: Filter results to namespaces owned by this user namespace:
* 0: Return all namespaces (subject to permission checks)
* LISTNS_CURRENT_USER: Namespaces owned by caller's user namespace
* Other value: Namespaces owned by the specified user namespace ID
*/
struct ns_id_req {
__u32 size; /* sizeof(struct ns_id_req) */
__u32 spare; /* Reserved, must be 0 */
__u64 ns_id; /* Last seen namespace ID (for pagination) */
__u32 ns_type; /* Filter by namespace type(s) */
__u32 spare2; /* Reserved, must be 0 */
__u64 user_ns_id; /* Filter by owning user namespace */
};
Example 1: List all namespaces
void list_all_namespaces(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0, /* Start from beginning */
.ns_type = 0, /* All types */
.user_ns_id = 0, /* All user namespaces */
};
uint64_t ids[100];
ssize_t ret;
printf("All namespaces in the system:\n");
do {
ret = listns(&req, ids, 100, 0);
if (ret < 0) {
perror("listns");
break;
}
for (ssize_t i = 0; i < ret; i++)
printf(" Namespace ID: %llu\n", (unsigned long long)ids[i]);
/* Continue from last seen ID */
if (ret > 0)
req.ns_id = ids[ret - 1];
} while (ret == 100); /* Buffer was full, more may exist */
}
Example 2 : List network namespaces only
void list_network_namespaces(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0,
.ns_type = NET_NS, /* Only network namespaces */
.user_ns_id = 0,
};
uint64_t ids[100];
ssize_t ret;
ret = listns(&req, ids, 100, 0);
if (ret < 0) {
perror("listns");
return;
}
printf("Network namespaces: %zd found\n", ret);
for (ssize_t i = 0; i < ret; i++)
printf(" netns ID: %llu\n", (unsigned long long)ids[i]);
}
Example 3 : List namespaces owned by current user namespace
void list_owned_namespaces(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0,
.ns_type = 0, /* All types */
.user_ns_id = LISTNS_CURRENT_USER, /* Current userns */
};
uint64_t ids[100];
ssize_t ret;
ret = listns(&req, ids, 100, 0);
if (ret < 0) {
perror("listns");
return;
}
printf("Namespaces owned by my user namespace: %zd\n", ret);
for (ssize_t i = 0; i < ret; i++)
printf(" ns ID: %llu\n", (unsigned long long)ids[i]);
}
Example 4 : List multiple namespace types
void list_network_and_mount_namespaces(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0,
.ns_type = NET_NS | MNT_NS, /* Network and mount */
.user_ns_id = 0,
};
uint64_t ids[100];
ssize_t ret;
ret = listns(&req, ids, 100, 0);
printf("Network and mount namespaces: %zd found\n", ret);
}
Example 5 : Pagination through large namespace sets
void list_all_with_pagination(void)
{
struct ns_id_req req = {
.size = sizeof(req),
.ns_id = 0,
.ns_type = 0,
.user_ns_id = 0,
};
uint64_t ids[50];
size_t total = 0;
ssize_t ret;
printf("Enumerating all namespaces with pagination:\n");
while (1) {
ret = listns(&req, ids, 50, 0);
if (ret < 0) {
perror("listns");
break;
}
if (ret == 0)
break; /* No more namespaces */
total += ret;
printf(" Batch: %zd namespaces\n", ret);
/* Last ID in this batch becomes start of next batch */
req.ns_id = ids[ret - 1];
if (ret < 50)
break; /* Partial batch = end of results */
}
printf("Total: %zu namespaces\n", total);
}
listns() respects namespace isolation and capabilities:
(1) Global listing (user_ns_id = 0):
- Requires CAP_SYS_ADMIN in the namespace's owning user namespace
- OR the namespace must be in the caller's namespace context (e.g.,
a namespace the caller is currently using)
- User namespaces additionally allow listing if the caller has
CAP_SYS_ADMIN in that user namespace itself
(2) Owner-filtered listing (user_ns_id != 0):
- Requires CAP_SYS_ADMIN in the specified owner user namespace
- OR the namespace must be in the caller's namespace context
- This allows unprivileged processes to enumerate namespaces they own
(3) Visibility:
- Only "active" namespaces are listed
- A namespace is active if it has a non-zero __ns_ref_active count
- This includes namespaces used by running processes, held by open
file descriptors, or kept active by bind mounts
- Inactive namespaces (kept alive only by internal kernel
references) are not visible via listns()
* patches from https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-0-2e6f823ebdc0@kernel.org: (74 commits)
selftests/namespace: test listns() pagination
selftests/namespace: add stress test
selftests/namespace: commit_creds() active reference tests
selftests/namespace: third threaded active reference count test
selftests/namespace: second threaded active reference count test
selftests/namespace: first threaded active reference count test
selftests/namespaces: twelth inactive namespace resurrection test
selftests/namespaces: eleventh inactive namespace resurrection test
selftests/namespaces: tenth inactive namespace resurrection test
selftests/namespaces: ninth inactive namespace resurrection test
selftests/namespaces: eigth inactive namespace resurrection test
selftests/namespaces: seventh inactive namespace resurrection test
selftests/namespaces: sixth inactive namespace resurrection test
selftests/namespaces: fifth inactive namespace resurrection test
selftests/namespaces: fourth inactive namespace resurrection test
selftests/namespaces: third inactive namespace resurrection test
selftests/namespaces: second inactive namespace resurrection test
selftests/namespaces: first inactive namespace resurrection test
selftests/namespaces: seventh listns() permission test
selftests/namespaces: sixth listns() permission test
...
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-0-2e6f823ebdc0@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Minimal test case to reproduce KASAN out-of-bounds in listns pagination.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-72-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Stress tests for namespace active reference counting.
These tests validate that the active reference counting system can
handle high load scenarios including rapid namespace
creation/destruction, large numbers of concurrent namespaces, and
various edge cases under stress.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-71-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test credential changes and their impact on namespace active references.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-70-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that namespaces become inactive after subprocess with multiple
threads exits. Create a subprocess that unshares user and network
namespaces, then creates two threads that share those namespaces. Verify
that after all threads and subprocess exit, the namespaces are no longer
listed by listns() and cannot be opened by open_by_handle_at().
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-69-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that a namespace remains active while a thread holds an fd to it.
Even after the thread exits, the namespace should remain active as long
as another thread holds a file descriptor to it.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-68-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that namespace becomes inactive after thread exits. This verifies
active reference counting works with threads, not just processes.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-67-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test multi-level namespace resurrection across three user namespace levels.
This test creates a complex namespace hierarchy with three levels of user
namespaces and a network namespace at the deepest level. It verifies that
the resurrection semantics work correctly when SIOCGSKNS is called on a
socket from an inactive namespace tree, and that listns() and
open_by_handle_at() correctly respect visibility rules.
Hierarchy after child processes exit (all with 0 active refcount):
net_L3A (0) <- Level 3 network namespace
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userns_L3 (0) <- Level 3 user namespace
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userns_L2 (0) <- Level 2 user namespace
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userns_L1 (0) <- Level 1 user namespace
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x
init_user_ns
The test verifies:
1. SIOCGSKNS on a socket from inactive net_L3A resurrects the entire chain
2. After resurrection, all namespaces are visible in listns()
3. Resurrected namespaces can be reopened via file handles
4. Closing the netns FD cascades down: the entire ownership chain
(userns_L3 -> userns_L2 -> userns_L1) becomes inactive again
5. Inactive namespaces disappear from listns() and cannot be reopened
6. Calling SIOCGSKNS again on the same socket resurrects the tree again
7. After second resurrection, namespaces are visible and can be reopened
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-66-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test combined listns() and file handle operations with socket-kept
netns. Create a netns, keep it alive with a socket, verify it appears in
listns(), then reopen it via file handle obtained from listns() entry.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-65-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that socket-kept netns can be reopened via file handle.
Verify that a network namespace kept alive by a socket FD can be
reopened using file handles even after the creating process exits.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-64-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that socket-kept netns appears in listns() output.
Verify that a network namespace kept alive by a socket FD appears in
listns() output even after the creating process exits, and that it
disappears when the socket is closed.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-63-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test IPv6 sockets also work with SIOCGSKNS.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-62-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test socket keeps netns active after creating process exits. Verify that
as long as the socket FD exists, the namespace remains active.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-61-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test multiple sockets keep the same network namespace active. Create
multiple sockets, verify closing some doesn't affect others.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-60-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test SIOCGSKNS fails on non-socket file descriptors.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-59-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test SIOCGSKNS across setns. Create a socket in netns A, switch to netns
B, verify SIOCGSKNS still returns netns A.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-58-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test SIOCGSKNS with different socket types (TCP, UDP, RAW).
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-57-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that socket file descriptors keep network namespaces active. Create
a network namespace, create a socket in it, then exit the namespace. The
namespace should remain active while the socket FD is held.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-56-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test basic SIOCGSKNS functionality. Create a socket and verify SIOCGSKNS
returns the correct network namespace.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-55-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that dropping CAP_SYS_ADMIN restricts what we can see.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-54-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that we can see user namespaces we have CAP_SYS_ADMIN inside of.
This is different from seeing namespaces owned by a user namespace.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-53-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that CAP_SYS_ADMIN in parent user namespace allows seeing
child user namespace's owned namespaces.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-52-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test permission checking with LISTNS_CURRENT_USER.
Verify that listing with LISTNS_CURRENT_USER respects permissions.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-51-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that users cannot see namespaces from unrelated user namespaces.
Create two sibling user namespaces, verify they can't see each other's
owned namespaces.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-50-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that users with CAP_SYS_ADMIN in a user namespace can see
all namespaces owned by that user namespace.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-49-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that unprivileged users can only see namespaces they're currently
in. Create a namespace, drop privileges, verify we can only see our own
namespaces.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-48-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test error cases for listns().
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-47-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that hierarchical active reference propagation keeps parent
user namespaces visible in listns().
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-46-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test listns() with multiple namespace types filter.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-45-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test listns() with specific user namespace ID.
Create a user namespace and list namespaces it owns.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-44-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that listns() only returns active namespaces.
Create a namespace, let it become inactive, verify it's not listed.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-43-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test listns() with LISTNS_CURRENT_USER.
List namespaces owned by current user namespace.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-42-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test listns() pagination.
List namespaces in batches.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-41-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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test listns() with type filtering.
List only network namespaces.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-40-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test basic listns() functionality with the unified namespace tree.
List all active namespaces globally.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-39-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add a wrapper for the listns() system call.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-38-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test different namespace types (net, uts, ipc) all contributing
active references to the same owning user namespace.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-37-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that user namespace as a child also propagates correctly.
Create user_A -> user_B, verify when user_B is active that user_A
is also active. This is different from non-user namespace children.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-36-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that parent stays active as long as ANY child is active.
Create parent user namespace with two child net namespaces.
Parent should remain active until BOTH children are inactive.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-35-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test hierarchical propagation with deep namespace hierarchy.
Create: init_user_ns -> user_A -> user_B -> net_ns
When net_ns is active, both user_A and user_B should be active.
This verifies the conditional recursion in __ns_ref_active_put() works.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-34-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test that different namespace types with same owner all contribute
active references to the owning user namespace.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-33-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test multiple children sharing same parent.
Parent should stay active as long as ANY child is active.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-32-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Test multi-level hierarchy (3+ levels deep).
Grandparent → Parent → Child
When child is active, both parent AND grandparent should be active.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-31-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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