.\" Copyright (c) 2018 Mariusz Zaborski .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .Dd December 6, 2023 .Dt CAP_GRP 3 .Os .Sh NAME .Nm cap_getgrent , .Nm cap_getgrnam , .Nm cap_getgrgid , .Nm cap_getgrent_r , .Nm cap_getgrnam_r , .Nm cap_getgrgid_r , .Nm cap_setgroupent , .Nm cap_setgrent , .Nm cap_endgrent , .Nm cap_grp_limit_cmds , .Nm cap_grp_limit_fields , .Nm cap_grp_limit_groups .Nd "library for group database operations in capability mode" .Sh LIBRARY .Lb libcap_grp .Sh SYNOPSIS .In sys/nv.h .In libcasper.h .In casper/cap_grp.h .Ft "struct group *" .Fn cap_getgrent "cap_channel_t *chan" .Ft "struct group *" .Fn cap_getgrnam "cap_channel_t *chan" "const char *name" .Ft "struct group *" .Fn cap_getgrgid "cap_channel_t *chan" "gid_t gid" .Ft "int" .Fn cap_getgrent_r "cap_channel_t *chan" "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result" .Ft "int" .Fn cap_getgrnam_r "cap_channel_t *chan" "const char *name" "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result" .Ft int .Fn cap_getgrgid_r "cap_channel_t *chan" "gid_t gid" "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result" .Ft int .Fn cap_setgroupent "cap_channel_t *chan" "int stayopen" .Ft int .Fn cap_setgrent "cap_channel_t *chan" .Ft void .Fn cap_endgrent "cap_channel_t *chan" .Ft int .Fn cap_grp_limit_cmds "cap_channel_t *chan" "const char * const *cmds" "size_t ncmds" .Ft int .Fn cap_grp_limit_fields "cap_channel_t *chan" "const char * const *fields" "size_t nfields" .Ft int .Fn cap_grp_limit_groups "cap_channel_t *chan" "const char * const *names" "size_t nnames" "const gid_t *gids" "size_t ngids" .Sh DESCRIPTION The functions .Fn cap_getgrent , .Fn cap_getgrnam , .Fn cap_getgrgid , .Fn cap_getgrent_r , .Fn cap_getgrnam_r , .Fn cap_getgrgid_r , .Fn cap_setgroupent , .Fn cap_setgrent , and .Fn cap_endgrent are respectively equivalent to .Xr getgrent 3 , .Xr getgrnam 3 , .Xr getgrgid 3 , .Xr getgrent_r 3 , .Xr getgrnam_r 3 , .Xr getgrgid_r 3 , .Xr setgroupent 3 , .Xr setgrent 3 , and .Xr endgrent 3 except that the connection to the .Nm system.grp service needs to be provided. .Pp The .Fn cap_grp_limit_cmds function limits the functions allowed in the service. The .Fa cmds variable can be set to .Dv getgrent , .Dv getgrnam , .Dv getgrgid , .Dv getgrent_r , .Dv getgrnam_r , .Dv getgrgid_r , .Dv setgroupent , .Dv setgrent , or .Dv endgrent which will allow to use the function associated with the name. The .Fa ncmds variable contains the number of .Fa cmds provided. .Pp The .Fn cap_grp_limit_fields function allows limit fields returned in the structure .Vt group . The .Fa fields variable can be set to .Dv gr_name .Dv gr_passwd .Dv gr_gid or .Dv gr_mem . The field which was set as the limit will be returned, while the rest of the values not set this way will have default values. The .Fa nfields variable contains the number of .Fa fields provided. .Pp The .Fn cap_grp_limit_groups function allows to limit access to groups. The .Fa names variable allows to limit groups by name and the .Fa gids variable by the group number. The .Fa nnames and .Fa ngids variables provide numbers of limited names and gids. .Pp All of these functions are reentrant but not thread-safe. That is, they may be called from separate threads only with different .Vt cap_channel_t arguments or with synchronization. .Sh EXAMPLES The following example first opens a capability to casper and then uses this capability to create the .Nm system.grp casper service and uses it to get a group name. .Bd -literal cap_channel_t *capcas, *capgrp; const char *cmds[] = { "getgrgid" }; const char *fields[] = { "gr_name" }; const gid_t gid[] = { 1 }; struct group *group; /* Open capability to Casper. */ capcas = cap_init(); if (capcas == NULL) err(1, "Unable to contact Casper"); /* Enter capability mode sandbox. */ if (cap_enter() < 0 && errno != ENOSYS) err(1, "Unable to enter capability mode"); /* Use Casper capability to create capability to the system.grp service. */ capgrp = cap_service_open(capcas, "system.grp"); if (capgrp == NULL) err(1, "Unable to open system.grp service"); /* Close Casper capability, we don't need it anymore. */ cap_close(capcas); /* Limit service to one single function. */ if (cap_grp_limit_cmds(capgrp, cmds, nitems(cmds))) err(1, "Unable to limit access to system.grp service"); /* Limit service to one field as we only need name of the group. */ if (cap_grp_limit_fields(capgrp, fields, nitems(fields))) err(1, "Unable to limit access to system.grp service"); /* Limit service to one gid. */ if (cap_grp_limit_groups(capgrp, NULL, 0, gid, nitems(gid))) err(1, "Unable to limit access to system.grp service"); group = cap_getgrgid(capgrp, gid[0]); if (group == NULL) err(1, "Unable to get name of group"); printf("GID %d is associated with name %s.\\n", gid[0], group->gr_name); cap_close(capgrp); .Ed .Sh SEE ALSO .Xr cap_enter 2 , .Xr endgrent 3 , .Xr err 3 , .Xr getgrent 3 , .Xr getgrent_r 3 , .Xr getgrgid 3 , .Xr getgrgid_r 3 , .Xr getgrnam 3 , .Xr getgrnam_r 3 , .Xr setgrent 3 , .Xr setgroupent 3 , .Xr capsicum 4 , .Xr nv 9 .Sh HISTORY The .Nm cap_grp service first appeared in .Fx 10.3 . .Sh AUTHORS The .Nm cap_grp service was implemented by .An Pawel Jakub Dawidek Aq Mt pawel@dawidek.net under sponsorship from the FreeBSD Foundation. .Pp This manual page was written by .An Mariusz Zaborski Aq Mt oshogbo@FreeBSD.org .