issetugid(2) [linux man page]

issetugid(2)                                                       System Calls                                                       issetugid(2)

NAME

       issetugid - determine if current executable is running setuid or setgid

SYNOPSIS

       #include <unistd.h>

       int issetugid(void);

DESCRIPTION

       The issetugid() function enables library functions (in libtermlib, libc, or other libraries) to guarantee safe behavior when used in setuid
       or setgid programs or programs that run with more privileges after a succesful exec(2). Some library functions might be passed insufficient
       information  and  not  know  whether  the  current program was started setuid or setgid because a higher level calling code might have made
       changes to the uid, euid, gid, or egid. These low-level library functions are therefore unable to determine if they are being run with ele-
       vated or normal privileges.

       The  issetugid()  function should be used to determine if a path name returned from a getenv(3C) call can be used safely to open the speci-
       fied file. It is often not safe to open such a file because the status of the effective uid is not known.

       The result of a call to issetugid() is unaffected by calls to setuid(), setgid(), or other such calls.  In case of a call to  fork(2),  the
       child process inherits the same status.

       The  status of issetugid() is affected only by execve() (see exec(2)). If a child process executes a new executable file, a new issetugid()
       status will be based on the existing process's uid, euid, gid, and egid permissions and on the modes of the executable  file.  If  the  new
       executable  file  modes  are setuid or setgid, or if the existing process is executing the new image with uid != euid or gid != egid, or if
       the permitted set before the call to the exec function is not a superset of the inheritable set at that time, issetugid() returns 1 in  the
       new process.

RETURN VALUES

       The  issetugid() function returns 1 if the process was made setuid or setgid as the result of the last or a previous call to execve(). Oth-
       erwise it returns 0.

ERRORS

       The issetugid() function is always successful. No return value is reserved to indicate an error.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Interface Stability          |Evolving                     |
       +-----------------------------+-----------------------------+
       |MT-Level                     |Async-Signal-Safe            |
       +-----------------------------+-----------------------------+

SEE ALSO

       exec(2), fork(2), setuid(2), getenv(3C), attributes(5), privileges(5)

SunOS 5.10                                                          19 Feb 2003                                                       issetugid(2)

setuid(2)							   System Calls 							 setuid(2)

NAME

       setuid, setegid, seteuid, setgid - set user and group IDs

SYNOPSIS

       #include <sys/types.h>
       #include <unistd.h>

       int setuid(uid_t uid);

       int setgid(gid_t gid);

       int seteuid(uid_t euid);

       int setegid(gid_t egid);

DESCRIPTION

       The  setuid()  function	sets the real user ID, effective user ID, and saved user ID of the calling process. The setgid() function sets the
       real group ID, effective group ID, and saved group ID of the calling process. The setegid() and seteuid() functions set the effective group
       and user IDs respectively for the calling process. See Intro(2) for more information on real, effective, and saved user and group IDs.

       At  login time, the real user ID, effective user ID, and saved user ID of the login process are set to the login ID of the user responsible
       for the creation of the process. The same is true for the real, effective, and saved group IDs; they are set to the group ID  of  the  user
       responsible for the creation of the process.

       When  a process calls one of the exec(2) family of functions to execute a file (program), the user and/or group identifiers associated with
       the process can change. If the file executed is a set-user-ID file, the effective and saved user IDs of the process are set to the owner of
       the  file  executed.  If the file executed is a set-group-ID file, the effective and saved group IDs of the process are set to the group of
       the file executed. If the file executed is not a set-user-ID or set-group-ID file, the effective user ID, saved user  ID,  effective  group
       ID, and saved group ID are not changed.

       If  the	{PRIV_PROC_SETID}  privilege is asserted in the effective set of the process calling setuid(), the real, effective, and saved user
       IDs are set to the uid argument.  If the uid argument is 0 and none of the saved, effective or  real  UID  is  0,  additional  restrictions
       apply. See privileges(5).

       If  the	{PRIV_PROC_SETID}  privilege  is not asserted in the effective set, but uid is either the real user ID or the saved user ID of the
       calling process, the effective user ID is set to uid.

       If the {PRIV_PROC_SETID} privilege is asserted in the effective set of the process calling setgid(), the real, effective, and  saved  group
       IDs are set to the gid argument.

       If  the	{PRIV_PROC_SETID} privilege is not asserted in the effective set, but gid is either the real group ID or the saved group ID of the
       calling process, the effective group ID is set to gid.

RETURN VALUES

       Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.

ERRORS

       The setuid() and setgid() functions will fail if:

       EINVAL	 The value of uid or gid is out of range.

       EPERM	 For setuid() and seteuid(), the {PRIV_PROC_SETID} privilege is not asserted in the effective set of the calling process  and  the
		 uid  argument does not match either the real or saved user IDs, or an attempt is made to change to UID 0 and none of the existing
		 UIDs is 0, in which case additional privileges are required.

		 For setgid() and setegid(), the {PRIV_PROC_SETID} privilege is not asserted in the effective set and the gid  argument  does  not
		 match either the real or saved group IDs.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       Intro(2), exec(2), getgroups(2), getuid(2), stat.h(3HEAD), attributes(5), privileges(5), standards(5)

SunOS 5.11							    20 Jan 2003 							 setuid(2)