Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
SETFSUID(2)		   Linux Programmer's Manual		   SETFSUID(2)

NAME
       setfsuid	- set user identity used for file system checks

SYNOPSIS
       #include	<unistd.h> /* glibc uses <sys/fsuid.h> */

       int setfsuid(uid_t fsuid);

DESCRIPTION
       The system call setfsuid	sets the user ID that the Linux	kernel uses to
       check for all accesses to the file system. Normally, the	value of fsuid
       will  shadow  the value of the effective	user ID. In fact, whenever the
       effective user ID is changed, fsuid will	also be	 changed  to  the  new
       value of	the effective user ID.

       Explicit	 calls	to setfsuid and	setfsgid are usually only used by pro-
       grams such as the Linux NFS server that need to change  what  user  and
       group  ID is used for file access without a corresponding change	in the
       real and	effective user and group IDs.  A change	in the normal user IDs
       for a program such as the NFS server is a security hole that can	expose
       it to unwanted signals. (But see	below.)

       setfsuid	will only succeed if the caller	is the superuser or  if	 fsuid
       matches	either the real	user ID, effective user	ID, saved set-user-ID,
       or the current value of fsuid.

RETURN VALUE
       On success, the previous	value of fsuid is  returned.   On  error,  the
       current value of	fsuid is returned.

CONFORMING TO
       setfsuid	 is Linux specific and should not be used in programs intended
       to be portable.	It is present since Linux 1.1.44  and  in  libc	 since
       libc 4.7.6.

BUGS
       No  error  messages of any kind are returned to the caller. At the very
       least, EPERM should be returned when the	call fails.

NOTES
       When glibc determines that the argument is not a	 valid	uid,  it  will
       return -1 and set errno to EINVAL without attempting the	system call.

       Note  that at the time this system call was introduced, a process could
       send a signal to	a process with the same	effective user ID.  Today sig-
       nal permission handling is slightly different.

SEE ALSO
       kill(2),	setfsgid(2)

Linux 1.3.15			  2002-07-23			   SETFSUID(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CONFORMING TO | BUGS | NOTES | SEE ALSO

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=setfsuid&sektion=2&manpath=Red+Hat+9>

home | help