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102eab95f0
Two administrator processes may race when setting child_ns_mode as one
process sets child_ns_mode to "local" and then creates a namespace, but
another process changes child_ns_mode to "global" between the write and
the namespace creation. The first process ends up with a namespace in
"global" mode instead of "local". While this can be detected after the
fact by reading ns_mode and retrying, it is fragile and error-prone.
Make child_ns_mode write-once so that a namespace manager can set it
once and be sure it won't change. Writing a different value after the
first write returns -EBUSY. This applies to all namespaces, including
init_net, where an init process can write "local" to lock all future
namespaces into local mode.
Fixes: eafb64f40c ("vsock: add netns to vsock core")
Suggested-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
Co-developed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260223-vsock-ns-write-once-v3-2-c0cde6959923@meta.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
25 lines
536 B
C
25 lines
536 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __NET_NET_NAMESPACE_VSOCK_H
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#define __NET_NET_NAMESPACE_VSOCK_H
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#include <linux/types.h>
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enum vsock_net_mode {
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VSOCK_NET_MODE_GLOBAL,
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VSOCK_NET_MODE_LOCAL,
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};
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struct netns_vsock {
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struct ctl_table_header *sysctl_hdr;
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/* protected by the vsock_table_lock in af_vsock.c */
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u32 port;
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enum vsock_net_mode mode;
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enum vsock_net_mode child_ns_mode;
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/* 0 = unlocked, 1 = locked to global, 2 = locked to local */
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int child_ns_mode_locked;
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};
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#endif /* __NET_NET_NAMESPACE_VSOCK_H */
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