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setregid(3p) — Linux manual page

PROLOG \|NAME \|SYNOPSIS \|DESCRIPTION \|RETURN VALUE \|ERRORS \|EXAMPLES \|APPLICATION USAGE \|RATIONALE \|FUTURE DIRECTIONS \|SEE ALSO \|COPYRIGHT

SETREGID(3P)            POSIX Programmer's ManualSETREGID(3P)

PROLOG top

       This manual page is part of the POSIX Programmer's Manual.  The       Linux implementation of this interface may differ (consult the       corresponding Linux manual page for details of Linux behavior), or       the interface may not be implemented on Linux.

NAME top

       setregid — set real and effective group IDs

SYNOPSIS top

       #include <unistd.h>       int setregid(gid_trgid, gid_tegid);

DESCRIPTION top

       Thesetregid() function shall set the real and effective group IDs       of the calling process.       Ifrgid is -1, the real group ID shall not be changed; ifegid is       -1, the effective group ID shall not be changed.       The real and effective group IDs may be set to different values in       the same call.       Only a process with appropriate privileges can set the real group       ID and the effective group ID to any valid value.       A non-privileged process can set either the real group ID to the       saved set-group-ID from one of theexec family of functions, or       the effective group ID to the saved set-group-ID or the real group       ID.       If the real group ID is being set (rgid is not -1), or the       effective group ID is being set to a value not equal to the real       group ID, then the saved set-group-ID of the current process shall       be set equal to the new effective group ID.       Any supplementary group IDs of the calling process remain       unchanged.

RETURN VALUE top

       Upon successful completion, 0 shall be returned. Otherwise, -1       shall be returned anderrno set to indicate the error, and neither       of the group IDs are changed.

ERRORS top

       Thesetregid() function shall fail if:EINVALThe value of thergid oregid argument is invalid or out-              of-range.EPERMThe process does not have appropriate privileges and a              change other than changing the real group ID to the saved              set-group-ID, or changing the effective group ID to the              real group ID or the saved set-group-ID, was requested.The following sections are informative.

EXAMPLES top

       None.

APPLICATION USAGE top

       If a non-privileged set-group-ID process sets its effective group       ID to its real group ID, it can only set its effective group ID       back to the previous value ifrgid was -1 in thesetregid() call,       since the saved-group-ID is not changed in that case. Ifrgid was       equal to the real group ID in thesetregid() call, then the saved       set-group-ID will also have been changed to the real user ID.

RATIONALE top

       Earlier versions of this standard did not specify whether the       saved set-group-ID was affected bysetregid() calls. This version       specifies common existing practice that constitutes an important       security feature. The ability to set both the effective group ID       and saved set-group-ID to be the same as the real group ID means       that any security weakness in code that is executed after that       point cannot result in malicious code being executed with the       previous effective group ID. Privileged applications could already       do this using justsetgid(), but for non-privileged applications       the only standard method available is to use this feature ofsetregid().

FUTURE DIRECTIONS top

       None.

COPYRIGHT top

       Portions of this text are reprinted and reproduced in electronic       form from IEEE Std 1003.1-2017, Standard for Information       Technology -- Portable Operating System Interface (POSIX), The       Open Group Base Specifications Issue 7, 2018 Edition, Copyright       (C) 2018 by the Institute of Electrical and Electronics Engineers,       Inc and The Open Group.  In the event of any discrepancy between       this version and the original IEEE and The Open Group Standard,       the original IEEE and The Open Group Standard is the referee       document. The original Standard can be obtained online athttp://www.opengroup.org/unix/online.html .       Any typographical or formatting errors that appear in this page       are most likely to have been introduced during the conversion of       the source files to man page format. To report such errors, seehttps://www.kernel.org/doc/man-pages/reporting_bugs.html .IEEE/The Open Group                2017SETREGID(3P)

Pages that refer to this page:unistd.h(0p), getegid(3p), geteuid(3p), getgid(3p), getuid(3p), setegid(3p), seteuid(3p), setgid(3p), setreuid(3p), setuid(3p)