132900e82SRobert Watson.\"- 2d1605766SRobert Watson.\" Copyright (c) 1999, 2000, 2001, 2003 Robert N. M. Watson 332900e82SRobert Watson.\" All rights reserved. 432900e82SRobert Watson.\" 532900e82SRobert Watson.\" Redistribution and use in source and binary forms, with or without 632900e82SRobert Watson.\" modification, are permitted provided that the following conditions 732900e82SRobert Watson.\" are met: 832900e82SRobert Watson.\" 1. Redistributions of source code must retain the above copyright 932900e82SRobert Watson.\" notice, this list of conditions and the following disclaimer. 1032900e82SRobert Watson.\" 2. Redistributions in binary form must reproduce the above copyright 1132900e82SRobert Watson.\" notice, this list of conditions and the following disclaimer in the 1232900e82SRobert Watson.\" documentation and/or other materials provided with the distribution. 1332900e82SRobert Watson.\" 1432900e82SRobert Watson.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 1532900e82SRobert Watson.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 1632900e82SRobert Watson.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 1732900e82SRobert Watson.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 1832900e82SRobert Watson.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 1932900e82SRobert Watson.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2032900e82SRobert Watson.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2132900e82SRobert Watson.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2232900e82SRobert Watson.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2332900e82SRobert Watson.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2432900e82SRobert Watson.\" SUCH DAMAGE. 2532900e82SRobert Watson.\" 26*e8fc6a99SMateusz Piotrowski.Dd September 5, 2023 2732900e82SRobert Watson.Dt EXTATTR 9 28aa12cea2SUlrich Spörlein.Os 2932900e82SRobert Watson.Sh NAME 3032900e82SRobert Watson.Nm extattr 3132900e82SRobert Watson.Nd virtual file system named extended attributes 3232900e82SRobert Watson.Sh SYNOPSIS 3332eef9aeSRuslan Ermilov.In sys/param.h 3432eef9aeSRuslan Ermilov.In sys/vnode.h 3532eef9aeSRuslan Ermilov.In sys/extattr.h 3632900e82SRobert Watson.Sh DESCRIPTION 3732900e82SRobert WatsonNamed extended attributes allow additional meta-data to be associated 3850b19f19SRobert Watsonwith vnodes representing files and directories. 3950b19f19SRobert WatsonThe semantics of this additional data is that of a "name=value" pair, where 4050b19f19SRobert Watsona name may be defined or undefined, and if defined, associated with zero or 4150b19f19SRobert Watsonmore bytes of arbitrary binary data. 4250b19f19SRobert WatsonExtended attribute names exist within a set of namespaces; each operation 4350b19f19SRobert Watsonon an extended attribute is required to provide the namespace to which to 4450b19f19SRobert Watsonoperation refers. 4550b19f19SRobert WatsonIf the same name is present in multiple namespaces, the extended attributes 4650b19f19SRobert Watsonassociated with the names are stored and manipulated independently. 4750b19f19SRobert WatsonThe following two namespaces are defined universally, although individual 4850b19f19SRobert Watsonfile systems may implement additional namespaces, or not implement 49e2cd9aedSRobert Watsonthese namespaces: 50e2cd9aedSRobert Watson.Dv EXTATTR_NAMESPACE_USER , 51e2cd9aedSRobert Watson.Dv EXTATTR_NAMESPACE_SYSTEM . 5250b19f19SRobert WatsonThe semantics of these attributes are intended to be as follows: user 53a910f192SDima Dorfmanattribute data is protected according the normal discretionary 5450b19f19SRobert Watsonand mandatory protections associated with the data in the file or 5550b19f19SRobert Watsondirectory; system attribute data is protected such that appropriate 5650b19f19SRobert Watsonprivilege is required to directly access or manipulate these attributes. 57*e8fc6a99SMateusz PiotrowskiBy default, processes in a 58315d7bbbSDmitry Chagin.Xr jail 8 59*e8fc6a99SMateusz Piotrowskicannot access the system attribute data unless the 60*e8fc6a99SMateusz Piotrowski.Va allow.extattr 61315d7bbbSDmitry Chaginconfiguration parameter is specified. 62ef994422SRuslan Ermilov.Pp 6350b19f19SRobert WatsonReads of extended attribute data may return specific contiguous regions of 6450b19f19SRobert Watsonthe meta-data, in the style of 6532900e82SRobert Watson.Xr VOP_READ 9 , 6632900e82SRobert Watsonbut writes will replace the entire current "value" associated with 6750b19f19SRobert Watsona given name. 6850b19f19SRobert WatsonAs there are a plethora of file systems with differing extended attributes, 6950b19f19SRobert Watsonavailability and functionality of these functions may be limited, and they 7050b19f19SRobert Watsonshould be used with awareness of the underlying semantics of the supporting 7150b19f19SRobert Watsonfile system. 7250b19f19SRobert WatsonAuthorization schemes for extended attribute data may also vary by file 7350b19f19SRobert Watsonsystem, as well as maximum attribute size, and whether or not any or 7450b19f19SRobert Watsonspecific new attributes may be defined. 753136363fSRuslan Ermilov.Pp 7632900e82SRobert WatsonExtended attributes are named using a null-terminated character string. 7750b19f19SRobert WatsonDepending on underlying file system semantics, this name may or may not be 78559eb8d2SHiten Pandyacase-sensitive. 79559eb8d2SHiten PandyaAppropriate vnode extended attribute calls are: 801792c88dSRobert Watson.Xr VOP_GETEXTATTR 9 , 811792c88dSRobert Watson.Xr VOP_LISTEXTATTR 9 , 8232900e82SRobert Watsonand 8332900e82SRobert Watson.Xr VOP_SETEXTATTR 9 . 8432900e82SRobert Watson.Sh SEE ALSO 85315d7bbbSDmitry Chagin.Xr jail 8 , 8632900e82SRobert Watson.Xr VFS 9 , 8732900e82SRobert Watson.Xr VOP_GETEXTATTR 9 , 881792c88dSRobert Watson.Xr VOP_LISTEXTATTR 9 , 896fe89339SBen Smithurst.Xr VOP_SETEXTATTR 9 9032900e82SRobert Watson.Sh AUTHORS 91571dba6eSHiten PandyaThis manual page was written by 9232900e82SRobert Watson.An Robert Watson . 9350b19f19SRobert Watson.Sh BUGS 9450b19f19SRobert WatsonIn addition, the interface does not provide a mechanism to retrieve 9550b19f19SRobert Watsonthe current set of available attributes; it has been suggested that 96e2cd9aedSRobert Watsonproviding a 97e2cd9aedSRobert Watson.Dv NULL 98e2cd9aedSRobert Watsonattribute name should cause a list of defined attributes for the passed file 99e2cd9aedSRobert Watsonor directory, but this is not currently implemented. 100