установить реальные и эффективные идентификаторы группы (set real and effective group IDs)
Пролог (Prolog)
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.
Имя (Name)
setregid — set real and effective group IDs
Синопсис (Synopsis)
#include <unistd.h>
int setregid(gid_t rgid, gid_t egid);
Описание (Description)
The setregid() function shall set the real and effective group
IDs of the calling process.
If rgid is -1, the real group ID shall not be changed; if egid 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 the exec 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.
Возвращаемое значение (Return value)
Upon successful completion, 0 shall be returned. Otherwise, -1
shall be returned and errno set to indicate the error, and
neither of the group IDs are changed.
Ошибки (Error)
The setregid() function shall fail if:
EINVAL The value of the rgid or egid argument is invalid or out-
of-range.
EPERM The 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.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
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 if rgid was -1 in the setregid() call,
since the saved-group-ID is not changed in that case. If rgid was
equal to the real group ID in the setregid() call, then the saved
set-group-ID will also have been changed to the real user ID.
Обоснование (Rationale)
Earlier versions of this standard did not specify whether the
saved set-group-ID was affected by setregid() 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 just setgid(), but for non-privileged
applications the only standard method available is to use this
feature of setregid().
Будущие направления (Future directions)
None.
Смотри также (See also)
exec(1p), getegid(3p), geteuid(3p), getgid(3p), getuid(3p),
setegid(3p), seteuid(3p), setgid(3p), setreuid(3p), setuid(3p)
The Base Definitions volume of POSIX.1‐2017, unistd.h(0p)
