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0470170247
It might not be feasible for users to start passt-repair after passt is started, on a migration target, but before the migration process starts. For instance, with libvirt, the guest domain (and, hence, passt) is started on the target as part of the migration process. At least for the moment being, there's no hook a libvirt user (including KubeVirt) can use to start passt-repair before the migration starts. Add a directory watch using inotify: if PATH is a directory, instead of connecting to it, we'll watch for a .repair socket file to appear in it, and then attempt to connect to that socket. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
74 lines
2.5 KiB
Groff
74 lines
2.5 KiB
Groff
.\" SPDX-License-Identifier: GPL-2.0-or-later
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.\" Copyright (c) 2025 Red Hat GmbH
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.\" Author: Stefano Brivio <sbrivio@redhat.com>
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.TH passt-repair 1
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.SH NAME
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.B passt-repair
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\- Helper setting TCP_REPAIR socket options for \fBpasst\fR(1)
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.SH SYNOPSIS
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.B passt-repair
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\fIPATH\fR
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.SH DESCRIPTION
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.B passt-repair
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is a privileged helper setting and clearing repair mode on TCP sockets on behalf
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of \fBpasst\fR(1), as instructed via single-byte commands over a UNIX domain
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socket.
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It can be used to migrate TCP connections between guests without granting
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additional capabilities to \fBpasst\fR(1) itself: to migrate TCP connections,
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\fBpasst\fR(1) leverages repair mode, which needs the \fBCAP_NET_ADMIN\fR
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capability (see \fBcapabilities\fR(7)) to be set or cleared.
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If \fIPATH\fR represents a UNIX domain socket, \fBpasst-repair\fR(1) attempts to
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connect to it. If it is a directory, \fBpasst-repair\fR(1) waits until a file
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ending with \fI.repair\fR appears in it, and then attempts to connect to it.
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.SH PROTOCOL
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\fBpasst-repair\fR(1) connects to \fBpasst\fR(1) using the socket specified via
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\fI--repair-path\fR option in \fBpasst\fR(1) itself. By default, the name is the
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same as the UNIX domain socket used for guest communication, suffixed by
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\fI.repair\fR.
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The messages consist of one 8-bit signed integer that can be \fITCP_REPAIR_ON\fR
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(1), \fITCP_REPAIR_OFF\fR (0), or \fITCP_REPAIR_OFF_NO_WP\fR (-1), as defined by
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the Linux kernel user API, and one to SCM_MAX_FD (253) sockets as SCM_RIGHTS
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(see \fBunix\fR(7)) ancillary message, sent by the server, \fBpasst\fR(1).
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The client, \fBpasst-repair\fR(1), replies with the same byte (and no ancillary
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message) to indicate success, and closes the connection on failure.
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The server closes the connection on error or completion.
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.SH NOTES
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\fBpasst-repair\fR(1) can be granted the \fBCAP_NET_ADMIN\fR capability
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(preferred, as it limits privileges to the strictly necessary ones), or it can
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be run as root.
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.SH AUTHOR
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Stefano Brivio <sbrivio@redhat.com>.
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.SH REPORTING BUGS
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Please report issues on the bug tracker at https://bugs.passt.top/, or
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send a message to the passt-user@passt.top mailing list, see
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https://lists.passt.top/.
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.SH COPYRIGHT
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Copyright (c) 2025 Red Hat GmbH.
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\fBpasst-repair\fR is free software: you can redistribute them and/or modify
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them under the terms of the GNU General Public License as published by the Free
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Software Foundation, either version 2 of the License, or (at your option) any
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later version.
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.SH SEE ALSO
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\fBpasst\fR(1), \fBqemu\fR(1), \fBcapabilities\fR(7), \fBunix\fR(7).
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