168 lines
5.3 KiB
Groff
168 lines
5.3 KiB
Groff
.\" $NetBSD: puffs_cred.3,v 1.5 2009/04/11 15:36:22 joerg Exp $
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.\"
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.\" Copyright (c) 2007 Antti Kantee. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd October 18, 2007
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.Dt PUFFS_CRED 3
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.Os
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.Sh NAME
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.Nm puffs_cred
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.Nd puffs credential and access control routines
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.Sh LIBRARY
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.Lb libpuffs
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.Sh SYNOPSIS
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.In puffs.h
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.Ft int
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.Fn puffs_cred_getuid "const struct puffs_cred *pcr" "uid_t *uid"
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.Ft int
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.Fn puffs_cred_getgid "const struct puffs_cred *pcr" "gid_t *gid"
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.Ft int
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.Fo puffs_cred_getgroups
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.Fa "const struct puffs_cred *pcr" "gid_t *gids" "short *ngids"
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.Fc
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.Pp
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.Ft bool
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.Fn puffs_cred_isuid "const struct puffs_cred *pcr" "uid_t uid"
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.Ft bool
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.Fn puffs_cred_hasgroup "const struct puffs_cred *pcr" "gid_t gid"
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.Ft bool
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.Fn puffs_cred_iskernel "const struct puffs_cred *pcr"
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.Ft bool
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.Fn puffs_cred_isfs "const struct puffs_cred *pcr"
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.Ft bool
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.Fn puffs_cred_isjuggernaut "const struct puffs_cred *pcr"
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.Pp
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.Ft int
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.Fo puffs_access
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.Fa "enum vtype type" "mode_t file_mode" "uid_t owner" "gid_t group"
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.Fa "mode_t access_mode" "const struct puffs_cred *pcr"
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.Fc
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.Ft int
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.Fo puffs_access_chown
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.Fa "uid_t owner" "gid_t group" "uid_t newowner" "gid_t newgroup"
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.Fa "const struct puffs_cred *pcr"
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.Fc
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.Ft int
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.Fo puffs_access_chmod
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.Fa "uid_t owner" "gid_t group" "enum vtype type" "mode_t newmode"
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.Fa "const struct puffs_cred *pcr"
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.Fc
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.Ft int
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.Fo puffs_access_times
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.Fa "uid_t owner" "gid_t group" "mode_t file_mode" "int va_utimes_null"
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.Fa "const struct puffs_cred *pcr"
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.Fc
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.Sh DESCRIPTION
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These functions can be used to check operation credentials and perform
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access control.
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The structure
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.Vt struct puffs_cred
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can contain two types of credentials: ones belonging to users and
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ones belonging to the kernel.
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The latter is further divided into generic kernel credentials and
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file system credentials.
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The general rule is that these should be treated as more powerful
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than superuser credentials, but the file system is free to treat
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them as it sees fit.
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.Ss Credentials
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The
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.Fn puffs_cred_get
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family of functions fetch the uid or gid(s) from the given credential
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cookie.
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They return 0 for success or \-1 for an error and set
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.Va errno .
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An error happens when the credentials represent kernel or file system
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credentials and do not contain an uid or gid(s).
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.Pp
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For
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.Fn puffs_cred_getgroups ,
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the argument
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.Fa gids
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should point to an array with room for
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.Fa *ngids
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elements.
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.Pp
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The
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.Fn puffs_cred_is
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family of functions return 1 if the truth value of the function for
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.Fa pcr
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is true and 0 if it is false.
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The function
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.Fn puffs_cred_isjuggernaut
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is true if
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.Fa pcr
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describes superuser, kernel or file system credentials.
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.Ss Access Control
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To help the programmers task of emulating normal kernel file system
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access control semantics, several helper functions are provided to
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check if access is allowed.
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They return 0 if access should be permitted or an errno value to
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indicate that access should be denied with the returned value.
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.Pp
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.Fn puffs_access
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is equivalent to the kernel
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.Fn vaccess
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function.
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The arguments specify current information of the file to be
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tested with the exception of
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.Fa access_mode ,
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which is a combination of
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.Dv PUFFS_VREAD ,
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.Dv PUFFS_VWRITE
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and
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.Dv PUFFS_VEXEC
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indicating the desired file access mode.
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.Pp
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The rest of the functions provide UFS semantics for operations.
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.Fn puffs_access_chown
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checks if it is permissible to chown a file with the current uid
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and gid to the new uid and gid with the credentials of
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.Fa pcr .
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.Pp
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.Fn puffs_access_chmod
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checks against permission to chmod a file of type
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.Fa type
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to the mode
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.Fa newmode .
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.Pp
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Finally,
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.Fn puffs_access_times
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checks if it is allowable to update the timestamps of a file.
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The argument
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.Fa va_utimes_null
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signals if the flags
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.Dv VA_UTIMES_NULL
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was set in
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.Fa va_vaflags
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of
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.Va struct vattr .
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If coming from a path where this information is unavailable, passing
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0 as this argument restricts the permission of modification to the
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owner and superuser.
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Otherwise the function checks for write permissions to the node and
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returns success if the caller has write permissions.
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.Sh SEE ALSO
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.Xr puffs 3 ,
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.Xr vnode 9
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