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CAP_PWD(3)		 BSD Library Functions Manual		    CAP_PWD(3)

NAME
     cap_getpwent, cap_getpwnam, cap_getpwuid, cap_getpwent_r, cap_getpwnam_r,
     cap_getpwuid_r, cap_setpassent, cap_setpwent, cap_endpwent,
     cap_pwd_limit_cmds, cap_pwd_limit_fields, cap_pwd_limit_users -- library
     for password database operations in capability mode

LIBRARY
     library "libcap_pwd"

SYNOPSIS
     #include <libcasper.h>
     #include <casper/cap_pwd.h>

     struct passwd *
     cap_getpwent(cap_channel_t	*chan);

     struct passwd *
     cap_getpwnam(cap_channel_t	*chan, const char *login);

     struct passwd *
     cap_getpwuid(cap_channel_t	*chan, uid_t uid);

     int
     cap_getpwent_r(cap_channel_t *chan, struct	passwd *pwd, char *buffer,
	 size_t	bufsize, struct	passwd **result);

     int
     cap_getpwnam_r(cap_channel_t *chan, const char *name, struct passwd *pwd,
	 char *buffer, size_t bufsize, struct passwd **result);

     int
     cap_getpwuid_r(cap_channel_t *chan, uid_t uid, struct passwd *pwd,
	 char *buffer, size_t bufsize, struct passwd **result);

     int
     cap_setpassent(cap_channel_t *chan, int stayopen);

     void
     cap_setpwent(cap_channel_t	*chan);

     void
     cap_endpwent(cap_channel_t	*chan);

     int
     cap_pwd_limit_cmds(cap_channel_t *chan, const char	* const	*cmds,
	 size_t	ncmds);

     int
     cap_pwd_limit_fields(cap_channel_t	*chan, const char * const *fields,
	 size_t	nfields);

     int
     cap_pwd_limit_users(cap_channel_t *chan, const char * const *names,
	 size_t	nnames,	uid_t *uids, size_t nuids);

DESCRIPTION
     The functions cap_getpwent(), cap_getpwnam(), cap_getpwuid(),
     cap_getpwent_r(), cap_getpwnam_r(), cap_getpwuid_r(), cap_setpassent(),
     cap_setpwent(), and cap_endpwent()	are respectively equivalent to
     getpwent(3), getpwnam(3), getpwuid(3), getpwent_r(3), getpwnam_r(3),
     getpwuid_r(3), setpassent(3), setpwent(3),	and cap_endpwent(3) except
     that the connection to the	system.pwd service needs to be provided.

     The cap_pwd_limit_cmds() function limits the functions allowed in the
     service.  The cmds	variable can be	set to getpwent, getpwnam, getpwuid,
     getpwent_r, getpwnam_r, getpwuid_r, setpassent, setpwent, or endpwent
     which will	allow to use the function associated with the name.  The ncmds
     variable contains the number of cmds provided.

     The cap_pwd_limit_fields()	function allows	limit fields returned in the
     structure passwd.	The fields variable can	be set to pw_name, pw_passwd,
     pw_uid, pw_gid, pw_change,	pw_class, pw_gecos, pw_dir, pw_shell,
     pw_expire or pw_fields The	field which was	set as the limit will be re-
     turned, while the rest of the values not set this way will	have default
     values.  The nfields variable contains the	number of fields provided.

     The cap_pwd_limit_users() function	allows to limit	access to users.  The
     names variable allows to limit users by name and the uids variable	by the
     user number.  The nnames and nuids	variables provide numbers of limited
     names and uids.

EXAMPLES
     The following example first opens a capability to casper and then uses
     this capability to	create the system.pwd casper service and uses it to
     get a user	name.

     cap_channel_t *capcas, *cappwd;
     const char	*cmds[]	= { "getpwuid" };
     const char	*fields[] = { "pw_name"	};
     uid_t uid[] = { 1 };
     struct passwd *passwd;

     /*	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.pwd service. */
     cappwd = cap_service_open(capcas, "system.pwd");
     if	(cappwd	== NULL)
	     err(1, "Unable to open system.pwd service");

     /*	Close Casper capability, we don't need it anymore. */
     cap_close(capcas);

     /*	Limit service to one single function. */
     if	(cap_pwd_limit_cmds(cappwd, cmds, nitems(cmds)))
	     err(1, "Unable to limit access to system.pwd service");

     /*	Limit service to one field as we only need name	of the user. */
     if	(cap_pwd_limit_fields(cappwd, fields, nitems(fields)))
	     err(1, "Unable to limit access to system.pwd service");

     /*	Limit service to one uid. */
     if	(cap_pwd_limit_users(cappwd, NULL, 0, uid, nitems(uid)))
	     err(1, "Unable to limit access to system.pwd service");

     passwd = cap_getpwuid(cappwd, uid[0]);
     if	(passwd	== NULL)
	     err(1, "Unable to get name	of user");

     printf("UID %d is associated with name %s.\n", uid[0], passwd->pw_name);

     cap_close(cappwd);

SEE ALSO
     cap_enter(2), endpwent(3),	err(3),	getpwent(3), getpwent_r(3),
     getpwnam(3), getpwnam_r(3), getpwuid(3), getpwuid_r(3), setpassent(3),
     setpwent(3), capsicum(4), nv(9)

HISTORY
     The cap_pwd service first appeared	in FreeBSD 10.3.

AUTHORS
     The cap_pwd service was implemented by Pawel Jakub	Dawidek
     <pawel@dawidek.net> under sponsorship from	the FreeBSD Foundation.

     This manual page was written by
     Mariusz Zaborski <oshogbo@FreeBSD.org>.

BSD				  May 5, 2020				   BSD
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | HISTORY | AUTHORS

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