8b51205638
With the change of the range of UIDs that is generated from the automatic ID (-1), it became apparent that there is a potential problem with these automatic IDs when upgrading: they may have changed, which means that persistent files that exist outside of the rootfs suddenly have a different owner. Add a caveat section to the manual, as well as an explanation of how to work around the problem. Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> [yann.morin.1998@free.fr: slight rewording] Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
106 lines
4.1 KiB
Plaintext
106 lines
4.1 KiB
Plaintext
// -*- mode:doc -*- ;
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// vim: set syntax=asciidoc:
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[[makeuser-syntax]]
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== Makeusers syntax documentation
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The syntax to create users is inspired by the makedev syntax, above, but
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is specific to Buildroot.
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The syntax for adding a user is a space-separated list of fields, one
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user per line; the fields are:
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|=================================================================
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|username |uid |group |gid |password |home |shell |groups |comment
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|=================================================================
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Where:
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- +username+ is the desired user name (aka login name) for the user.
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It can not be +root+, and must be unique. If set to +-+, then just a
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group will be created.
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- +uid+ is the desired UID for the user. It must be unique, and not
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+0+. If set to +-1+ or +-2+, then a unique UID will be computed by
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Buildroot, with +-1+ denoting a system UID from [100...999] and +-2+
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denoting a user UID from [1000...1999].
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- +group+ is the desired name for the user's main group. It can not
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be +root+. If the group does not exist, it will be created.
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- +gid+ is the desired GID for the user's main group. It must be unique,
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and not +0+. If set to +-1+ or +-2+, and the group does not already
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exist, then a unique GID will be computed by Buildroot, with +-1+
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denoting a system GID from [100...999] and +-2+ denoting a user GID
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from [1000...1999].
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- +password+ is the crypt(3)-encoded password. If prefixed with +!+,
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then login is disabled. If prefixed with +=+, then it is interpreted
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as clear-text, and will be crypt-encoded (using MD5). If prefixed with
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+!=+, then the password will be crypt-encoded (using MD5) and login
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will be disabled. If set to +*+, then login is not allowed. If set to
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+-+, then no password value will be set.
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- +home+ is the desired home directory for the user. If set to '-', no
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home directory will be created, and the user's home will be +/+.
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Explicitly setting +home+ to +/+ is not allowed.
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- +shell+ is the desired shell for the user. If set to +-+, then
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+/bin/false+ is set as the user's shell.
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- +groups+ is the comma-separated list of additional groups the user
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should be part of. If set to +-+, then the user will be a member of
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no additional group. Missing groups will be created with an arbitrary
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+gid+.
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- +comment+ (aka https://en.wikipedia.org/wiki/Gecos_field[GECOS]
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field) is an almost-free-form text.
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There are a few restrictions on the content of each field:
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* except for +comment+, all fields are mandatory.
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* except for +comment+, fields may not contain spaces.
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* no field may contain a colon (+:+).
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If +home+ is not +-+, then the home directory, and all files below,
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will belong to the user and its main group.
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Examples:
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----
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foo -1 bar -1 !=blabla /home/foo /bin/sh alpha,bravo Foo user
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----
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This will create this user:
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- +username+ (aka login name) is: +foo+
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- +uid+ is computed by Buildroot
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- main +group+ is: +bar+
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- main group +gid+ is computed by Buildroot
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- clear-text +password+ is: +blabla+, will be crypt(3)-encoded, and login is disabled.
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- +home+ is: +/home/foo+
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- +shell+ is: +/bin/sh+
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- +foo+ is also a member of +groups+: +alpha+ and +bravo+
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- +comment+ is: +Foo user+
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----
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test 8000 wheel -1 = - /bin/sh - Test user
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----
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This will create this user:
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- +username+ (aka login name) is: +test+
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- +uid+ is : +8000+
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- main +group+ is: +wheel+
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- main group +gid+ is computed by Buildroot, and will use the value defined in the rootfs skeleton
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- +password+ is empty (aka no password).
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- +home+ is +/+ but will not belong to +test+
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- +shell+ is: +/bin/sh+
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- +test+ is not a member of any additional +groups+
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- +comment+ is: +Test user+
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=== Caveat with automatic UIDs and GIDs
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When updating buildroot or when packages are added or removed to/from
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the configuration, it is possible that the automatic UIDs and GIDs are
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changed. This can be a problem if persistent files were created with
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that user or group: after upgrade, they will suddenly have a different
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owner.
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Therefore, it is advisable to perpetuate the automatic IDs. This can be
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done by adding a users table with the generated IDs. It is only needed
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to do this for UIDs that actually create persistent files, e.g. database.
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