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SETREUID(2) | Linux Programmer's Manual | SETREUID(2) |
NAME¶
setreuid, setregid - set real and/or effective user or group IDSYNOPSIS¶
#include <sys/types.h>Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
DESCRIPTION¶
setreuid() sets real and effective user IDs of the calling process.RETURN VALUE¶
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.ERRORS¶
- EAGAIN
- The call would change the caller's real UID (i.e., ruid does not match the caller's real UID), but there was a temporary failure allocating the necessary kernel data structures.
- EAGAIN
- ruid does not match the caller's real UID and this call would bring the number of processes belonging to the real user ID ruid over the caller's RLIMIT_NPROC resource limit. Since Linux 3.1, this error case no longer occurs (but robust applications should check for this error); see the description of EAGAIN in execve(2).
- EINVAL
- One or more of the target user or group IDs is not valid in this user namespace.
- EPERM
- The calling process is not privileged (on Linux, does not have the necessary capability in its user namespace: CAP_SETUID in the case of setreuid(), or CAP_SETGID in the case of setregid()) and a change other than (i) swapping the effective user (group) ID with the real user (group) ID, or (ii) setting one to the value of the other or (iii) setting the effective user (group) ID to the value of the saved set-user-ID (saved set-group-ID) was specified.
CONFORMING TO¶
POSIX.1-2001, POSIX.1-2008, 4.3BSD (setreuid() and setregid() first appeared in 4.2BSD).NOTES¶
Setting the effective user (group) ID to the saved set-user-ID (saved set-group-ID) is possible since Linux 1.1.37 (1.1.38).C library/kernel differences¶
At the kernel level, user IDs and group IDs are a per-thread attribute. However, POSIX requires that all threads in a process share the same credentials. The NPTL threading implementation handles the POSIX requirements by providing wrapper functions for the various system calls that change process UIDs and GIDs. These wrapper functions (including those for setreuid() and setregid()) employ a signal-based technique to ensure that when one thread changes credentials, all of the other threads in the process also change their credentials. For details, see nptl(7).SEE ALSO¶
getgid(2), getuid(2), seteuid(2), setgid(2), setresuid(2), setuid(2), capabilities(7), credentials(7), user_namespaces(7)COLOPHON¶
This page is part of release 4.10 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.2016-10-08 | Linux |