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SUSER(9)	       FreeBSD Kernel Developer's Manual	      SUSER(9)

NAME
     suser, suser_cred -- check	if credentials have superuser privileges

SYNOPSIS
     #include <sys/priv.h>

     int
     suser(struct thread *td);

     int
     suser_cred(struct ucred *cred, int	flag);

DESCRIPTION
     The suser() and suser_cred() functions check if the credentials given
     include superuser powers.

     These interfaces have now been obsoleted by priv(9), and are provided
     only for compatibility with third party kernel modules that have not yet
     been updated to the new interface.	 They should not be used in any	new
     kernel code.

     The suser() function is the most common, and should be used unless	spe-
     cial circumstances	dictate	otherwise.

     The suser_cred() function should be used when the credentials to be
     checked are not the thread's own, when there is no	thread,	when superuser
     powers should be extended to imprisoned roots, or when the	credential to
     be	checked	is the real user rather	than the effective user.

     Whether or	not a privilege	is permitted in	a jail(8) depends on logic in
     prison_priv_check().

     In	general, privileges are	assigned based on the effective	user ID; in
     some cases, the real user ID may be used.

     The flags field is	currently unused.

     The suser() and suser_cred() functions note the fact that superuser pow-
     ers have been used	in the process structure of the	process	specified.
     Because part of their function is to notice whether superuser powers have
     been used,	the functions should only be called after other	permission
     possibilities have	been exhausted.

RETURN VALUES
     The suser() and suser_cred() functions return 0 if	the user has superuser
     powers and	EPERM otherwise.  This is the reverse logic of some other
     implementations of	suser()	in which a TRUE	response indicates superuser
     powers.

SEE ALSO
     chroot(2),	jail(2), priv(9)

BUGS
     The suser() and suser_cred() functions do not, in fact, record that supe-
     ruser privileges have been	used, and have not done	so since August	2000.

FreeBSD	10.1			August 30, 2007			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | BUGS

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