.\"
.\" Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
.\" Written by David Howells (dhowells@redhat.com)
.\"
.\" This program is free software; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License
.\" as published by the Free Software Foundation; either version
.\" 2 of the License, or (at your option) any later version.
.\"
.TH KEYCTL_SETPERM 3 "4 May 2006" Linux "Linux Key Management Calls"
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.SH NAME
keyctl_setperm \- change the permissions mask on a key
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.SH SYNOPSIS
.nf
.B #include <keyutils.h>
.sp
.BI "long keyctl_setperm(key_serial_t " key ", key_perm_t " perm ");"
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.SH DESCRIPTION
.BR keyctl_setperm ()
changes the permissions mask on a key.
.P
A process that does not have the
.B SysAdmin
capability may not change the permissions mask on a key that doesn't have the
same UID as the caller.
.P
The caller must have
.B setattr
permission on a key to be able change its permissions mask.
.P
The permissions mask is a bitwise-OR of the following flags:
.TP
.B KEY_xxx_VIEW
Grant permission to view the attributes of a key.
.TP
.B KEY_xxx_READ
Grant permission to read the payload of a key or to list a keyring.
.TP
.B KEY_xxx_WRITE
Grant permission to modify the payload of a key or to add or remove links
to/from a keyring.
.TP
.B KEY_xxx_SEARCH
Grant permission to find a key or to search a keyring.
.TP
.B KEY_xxx_LINK
Grant permission to make links to a key.
.TP
.B KEY_xxx_SETATTR
Grant permission to change the ownership and permissions attributes of a key.
.TP
.B KEY_xxx_ALL
Grant all the above.
.P
The
.RB ' xxx '
in the above should be replaced by one of:
.TP
.B POS
Grant the permission to a process that possesses the key (has it attached
searchably to one of the process's keyrings).
.TP
.B USR
Grant the permission to a process with the same UID as the key.
.TP
.B GRP
Grant the permission to a process with the same GID as the key, or with a
match for the key's GID amongst that process's Groups list.
.TP
.B OTH
Grant the permission to any other process.
.P
Examples include:
.BR KEY_POS_VIEW ", " KEY_USR_READ ", " KEY_GRP_SEARCH " and " KEY_OTH_ALL .
.P
User, group and other grants are exclusive: if a process qualifies in
the 'user' category, it will not qualify in the 'groups' category; and if a
process qualifies in either 'user' or 'groups' then it will not qualify in
the 'other' category.
.P
Possessor grants are cumulative with the grants from the 'user', 'groups'
and 'other' categories.
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.SH RETURN VALUE
On success
.BR keyctl_setperm ()
returns
.B 0 .
On error, the value
.B -1
will be returned and
.I errno
will have been set to an appropriate error.
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.SH ERRORS
.TP
.B ENOKEY
The specified key does not exist.
.TP
.B EKEYEXPIRED
The specified key has expired.
.TP
.B EKEYREVOKED
The specified key has been revoked.
.TP
.B EACCES
The named key exists, but does not grant
.B setattr
permission to the calling process.
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.SH LINKING
This is a library function that can be found in
.IR libkeyutils .
When linking,
.B -lkeyutils
should be specified to the linker.
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.SH SEE ALSO
.BR keyctl (1),
.br
.BR add_key (2),
.br
.BR keyctl (2),
.br
.BR request_key (2),
.br
.BR keyctl (3),
.br
.BR keyutils (7),
.br
.BR keyrings (7)